JP3669214B2 - Shift control device for continuously variable transmission for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device that performs shift control during kickdown in a continuously variable transmission for a vehicle.
[0002]
[Prior art]
A continuously variable transmission capable of continuously controlling a gear ratio can avoid a shift shock and is used in a vehicle as a power transmission device with excellent fuel consumption efficiency.
Even in such a continuously variable transmission, when there is a sudden acceleration request, kick-down control is performed in the same manner as a stepped transmission. In this kickdown control, first, the engine speed is increased as quickly as possible, and then the vehicle speed is increased. However, if the vehicle speed is increased after sufficiently increasing the rotational speed of the engine, it takes time until the vehicle speed increases, and the driver may feel uncomfortable. Therefore, the present applicant has developed a technology that allows kicking down in a continuously variable transmission with a good feeling and has filed an application as Japanese Patent Application No. 4-178622 (Japanese Patent No. 2751743).
[0003]
According to the technology disclosed in this publication, in order to bring the primary pulley closer to the target rotational speed, a temporary target rotational speed is set, and based on this control, the primary pulley and the engine are rotated, and the secondary pulley is By increasing the rotation and the vehicle speed, the vehicle speed can be increased more promptly after kick-down, and the driving feeling can be improved.
[0004]
[Problems to be solved by the invention]
However, in the above-described prior art, the temporary target rotational speed used for the control is based on the predicted primary pulley rotational speed because the predicted primary pulley rotational speed is obtained by adding a corrected rotational speed determined only according to the elapsed time from the predicted time point. Even if the throttle opening θth changes during the control, the temporary target rotation speed is not changed. For this reason, even if the driver further increases the accelerator opening to accelerate, the above-described temporary target rotational speed does not reflect the change in the throttle opening θth, so that the driver's acceleration request is not sufficiently satisfied. On the other hand, even if the driver reduces the accelerator opening so as to weaken the acceleration, similarly, the change in the throttle opening θth is not reflected in the temporary target rotation speed, so the driver's acceleration suppression request is not sufficiently satisfied.
[0005]
The present invention has been devised in view of the above-described problems, and at the time of kickdown, a temporary target rotational speed lower than the target rotational speed during the primary pulley rotational control based on the target rotational speed according to the engine load information. In this system, the vehicle speed can be increased quickly by performing control based on the above, so that the degree of acceleration requested by the driver can be obtained by reflecting the driver's degree of acceleration intention in the temporary target rotation speed. Another object of the present invention is to provide a shift control device for a continuously variable transmission for a vehicle.
[0006]
[Means for Solving the Problems]
Therefore, in the transmission control device for a continuously variable transmission for a vehicle according to the present invention, when the kickdown is determined, the rotation of the first rotating member is controlled based on the target rotational speed set based on the load information and the vehicle speed information. However, the target rotational speed is switched to the temporary target rotational speed set based on the rate of increase of the actual rotational speed, the elapsed time from the time of calculating the rate of increase, and the load information. Therefore, by adopting the temporary target rotational speed, the speed of the second rotating member (that is, the increase in the vehicle speed) is quickly increased, and the temporary target rotational speed is corrected according to the load information. Appropriate shift control is performed according to the request and acceleration suppression request.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a shift control device for a continuously variable transmission for a vehicle according to an embodiment of the present invention. FIG. 1 is a block diagram showing the configuration thereof, and FIG. 2 explains the continuously variable transmission. It is a schematic diagram for. In this embodiment, a belt type continuously variable transmission (CVT) is used as the transmission.
[0008]
First, the power transmission mechanism provided with the continuously variable transmission according to the present embodiment will be described. As shown in FIGS. 2A and 2B, the power transmission mechanism outputs power from the engine (internal combustion engine) 1. The rotation is transmitted to the front differential 31 through the torque converter (torque converter) 2, the forward / reverse switching mechanism 4, and the belt-type continuously variable transmission (CVT) 20 to drive the drive wheels 30.
[0009]
The continuously variable transmission mechanism 20 includes a primary pulley (first rotating member) 21 connected to the output side of the engine 1, a secondary pulley (second rotating member) 22 connected to the drive wheel 30 side of the vehicle, and both pulleys. The rotation input from the forward / reverse switching mechanism 4 to the primary shaft 24 is transmitted from the primary pulley 21 coaxial with the primary shaft 24 via the belt 23. Are input to the secondary pulley 22.
[0010]
The primary pulley 21 and the secondary pulley 22 are composed of two sheaves 21a, 21b, 22a, 22b that rotate together. Each sheave 21a, 22a is a fixed sheave fixed in the axial direction, and the other sheave 21b, 22b is a movable sheave movable in the axial direction by hydraulic actuators (hydraulic pistons) 21c, 22c.
[0011]
The hydraulic pistons 21c and 22c are supplied with a control hydraulic pressure obtained by pressurizing the hydraulic oil in the oil tank 61 with the oil pump 62, and in response to this, the movable sheaves 21b and 22b are pushed toward the fixed sheaves 21a and 22a. The pressure is adjusted. A line pressure regulated by a pressure regulating valve 63 is applied to the hydraulic piston 22 c of the secondary pulley 22, and a flow rate is regulated by the flow control valve 64 after being regulated by the pressure regulating valve 63 to the hydraulic piston 21 c of the primary pulley 21. The adjusted hydraulic fluid is supplied, and this hydraulic fluid acts as a gear ratio adjusting hydraulic pressure.
[0012]
The line pressure P ₁ applied to the hydraulic piston 22 c of the secondary pulley 22 and the gear ratio adjustment hydraulic pressure P ₂ applied to the hydraulic piston 21 c of the primary pulley 21 are determined by command signals from a controller (electronic control unit = ECU) 50. , Each is to be done.
The ECU 50 detects an engine speed sensor (crank angle sensor or cam angle sensor) 41, a throttle opening sensor 46, a first rotation speed sensor 43 that detects the rotation speed of the primary pulley 21, and a rotation speed of the secondary pulley 22. The detection signals of the second rotation speed sensor 44, the line pressure sensor 45 for detecting the line pressure, the vehicle speed sensor 47, and the like are input, and the ECU 50 receives the pulleys 21 and 22 based on these detection signals. The pressure regulating valve 63 and the flow rate control valve 64 provided in the hydraulic pressure supply system are controlled.
[0013]
In particular, the gear ratio adjustment hydraulic pressure is controlled by a control function (shift control means) 51 in the ECU 50. The shift control means 51 includes target rotation speed setting means 52, kickdown determination means 53 for determining whether or not kickdown is necessary from load information (here, throttle opening information) of the engine 1, and kickdown determination means. When it is determined by 53 that kick down is necessary, functional elements for executing kick down control, that is, primary pulley rotation control means (first rotation member control means) 54, primary pulley rotation speed estimation means (rotation speed estimation) Means) 55 and provisional target rotational speed setting means 56.
[0014]
The target rotational speed setting means 52 is a predetermined rotational speed of the primary pulley based on the vehicle speed V detected by the vehicle speed sensor 47 and the throttle opening (engine load information) θth detected by the throttle opening sensor 46 in a predetermined cycle. W _PT0 (referred to as the true target rotational speed) is calculated, and this true target rotational speed W _PT0 is normally set as the target rotational speed W _PT of the primary pulley 21. Even when the kick down control, the vehicle speed V, the although the target rotational speed W _PT true basic primary pulley 21 the target rotational speed W _PT0 according to the throttle opening [theta] th, during the kick down control will be described later The temporary target rotational speed W _PT1 set by the temporary target rotational speed setting means 56 is used as the target rotational speed W _PT .
[0015]
The kick-down determination means 53 determines that rapid acceleration is instructed when the throttle opening change rate dθth / dt obtained by time differentiation of the throttle opening θth value obtained at a predetermined cycle is equal to or greater than a predetermined value Δθth _0. Determine that down is required.
The throttle opening information may be any information as long as it represents load information of the engine 1, and may be determined based on, for example, an accelerator opening (accelerator pedal depression amount), an accelerator opening change rate, or a kickdown signal. .
[0016]
The primary pulley rotation control means 54 has a flow rate so that the actual rotation speed W _Pr of the primary pulley 21 becomes the target rotation speed W _PT set by the target rotation speed setting means 52 during normal operation (including kick-down control). The hydraulic piston 21c of the primary pulley 21 is feedback-controlled through the control valve 64, and the movable sheave 21b is appropriately driven to control the rotation speed of the primary pulley 21 and the engine rotation speed.
[0017]
The rotational speed estimation means 55 determines the time from the count value of the timer 48 started at the control start time T ₀ during kickdown control, and controls the primary pulley 21 actual rotational speed W _{Pr under} the control of the primary pulley rotation control means 54. The increase rate m of the actual rotational speed W _Pr of the primary pulley 21 is calculated from the first time point T ₁ to the second time point T ₂ when the speed increases toward the target rotational speed W _PT , and this increase Based on the rate m, the rotational speed W _Pr of the primary pulley 21 at the third time point T ₃ is estimated. That is, from the detection result of the first rotation speed sensor 43, the actual rotation speed W _P1 of the primary pulley 21 at the first time point T _{1 and} the actual rotation speed W _P2 of the primary pulley 21 at the second time point T ₂ are _expressed by the equation: m = The rate of increase m is calculated from (W _P2 −W _P1 ) / (T ₂ −T ₁ ).
[0018]
Since immediately after the kick down control starts by the output torque variation of the engine actual rotation speed W _Pr of the primary pulley 21 varies, as variations of the actual rotational speed W _Pr calculates the increase rate m from somewhat subsided, A first time T ₁ is set in advance based on experimental results and the like. Further, the third time point T ₃ is set to a fixed value as a time point at which the increase responsiveness of the vehicle speed and the increase of the engine speed are balanced. The third time point T ₃ is, for example, a throttle at the time of kickdown determination A variable value that is inversely proportional to the opening change rate dθth / dt or a variable value that is proportional to the vehicle speed may be used. The second time point T ₂ are, of course becomes a time point earlier than the third time point T ₃ later than the first time point T _1, the rate of increase first time point T ₁ Considering the calculation accuracy of m preferably to take a time between the second time point T ₂ sufficiently.
[0019]
Temporary target rotational speed setting means 56 is obtained by the actual rotational speed W _Pr (e.g. second point in time T ₂ of the increase rate m and the primary pulley 21 of the actual rotational speed W _Pr of the primary pulley 21 estimated by the rotation speed estimation unit 55 From the measured value W _P2 ), the rotational speed W _P3 [= W _P2 + m · (T ₃ −T ₂ )] of the primary pulley 21 predicted to be reached at the third time point is calculated, and this rotational speed W _P3 is calculated. By adding the first correction amount W _PA that increases in accordance with the elapsed time from the second time point T ₂ and the second correction amount W _th in accordance with the throttle opening θth obtained in a predetermined cycle, the temporary target rotation Set the speed W _PT1 (= W _P3 + W _PA + W _th ). Since the initial values of the first correction amount W _PA and the second correction amount W _th are set to zero, the value W _P3 is output as the temporary target rotation speed W _PT1 .
[0020]
The first correction amount W _PA is obtained when the difference W _PD (= W _PT0 −W _PT1 ) between the true target rotational speed W _PT0 and the temporary target rotational speed W _PT1 is larger than the first predetermined value α (second time point T). ₂ to the fourth time point T ₄ ), a correction amount W _PA that increases linearly according to the elapsed time (elapsed time from the second time point T ₂ ) as shown by the solid line in FIG. W _PD is When turned within the first predetermined value alpha (4th time T ₄ and later), the correction amount W _PA in accordance with the elapsed time as indicated by one-dot chain lines in FIG. 4 (elapsed time from the fourth time point T ₄₎ The correction amount W _PA ′ that increases linearly more slowly than that is adopted.
[0021]
As shown in FIG. 5A, the second correction amount W _th is set to increase linearly as the throttle opening θth increases. However, the second correction amount W _th, during acceleration control by the temporary target rotational speed W _PT1, to reflect the change in the throttle opening degree θth corresponding to driver acceleration intent of this temporary target rotational speed W _PT1 corresponding control However, if the throttle opening θth is extremely manipulated and this is directly reflected in the control, the acceleration control becomes unstable. Therefore, the second correction amount W _th is fixed to 0 in the region where the throttle opening θth is small, and the second correction amount W _th is fixed to the maximum value W _thMAX in the region where the throttle opening θth is small.
[0022]
A correction amount related value ΔW _th is set according to the throttle opening θth with the characteristics shown in FIG. 5B, and the formula: W _PT1 = W _P3 + ΣΔW _th (where ΣΔW _th is the time integral value of ΔW _th The temporary target rotational speed W _PT1 can be set with substantially the same characteristics as described above even if the temporary target rotational speed W _PT1 is set.
Further, as shown in FIG. 5C, the second correction amount W _th may be set to W _th ′ according to the throttle opening speed (time differential value of the throttle opening) dθth / dt. That is, the second correction amount W _th ′ is set to be proportional to the throttle opening speed dθth / dt. However, in consideration of the stability of the acceleration control, the second correction amount W _th ′ is fixed to the maximum value W _thMAX ′ in the region where the throttle opening speed dθth / dt is large.
[0023]
Further, the second correction amount W _th set with the characteristics shown in FIG. 5A and the second correction amount W _th ′ set with the characteristics shown in FIG. 5C are added together. It is also conceivable to set the temporary target rotational speed W _PT1 (= W _P3 + W _PA + W _th + W _th ′).
Here, the second correction amount W _th is set based on the throttle opening, but the second correction amount W _th is set based on the load information of the engine 1 (representing the driver's acceleration intention). For example, information on the accelerator opening (accelerator pedal depression amount) may be used directly.
[0024]
The map relating to the first correction amount W _{PA in} FIG. 4 takes into account the addition of the second correction amounts W _th , ΔW _th , W _th ′, and the first correction amount W than that disclosed in Japanese Patent No. 2751743. _It is preferable to suppress the increase rate of _PA (reduce the slope of the characteristic line).
The first predetermined value α may be a constant value or may be variable. For example, the first predetermined value α may be increased in response to an increase in the time change rate (dW _Pr / dt) of the actual rotation speed W _Pr .
[0025]
The target rotational speed setting means 52, at the time of kick-down control, while determining the time from the count value of the timer 48, from the control start time T ₀ of the kick-down to a third time point T _3, the true target rotational speed W _PT0 Used for the target rotational speed W _PT of the primary pulley 21 and from the third time point T ₃ to the fifth time point T ₅ (a time point when the difference W _PD is sufficiently smaller than the first predetermined value α and close to 0). When the temporary target rotational speed W _PT1 set by the speed setting means 56 is used as the target rotational speed W _PT and the difference W _PD decreases to a small threshold value or 0, the true target rotational speed W _{PT0 is obtained} at the fifth time point T _{5. Is} used for the target rotational speed _WPT .
[0026]
Since the shift control device for a continuously variable transmission for a vehicle according to an embodiment of the present invention is configured as described above, as shown in FIGS. 3 (a) and 3 (b), the throttle opening (engine Load information) When the change rate dθth / dt of θth becomes equal to or greater than the predetermined value Δθth ₀ (time T ₀ ′), the kick-down determination means 53 determines that kick down is necessary, and starts after time T ₀ ′ kick-down control is started from the time T _0.
[0027]
At the start of the kickdown control, the target rotational speed setting means 52 calculates the true target rotational speed W _PT0 of the primary pulley from the vehicle speed V and the throttle opening θth, and the primary pulley rotational control means 54 With the speed W _PT0 as the target rotational speed W _PT , the hydraulic control amount is set so that the actual rotational speed W _Pr of the primary pulley becomes the target rotational speed W _PT0 , that is, so that the rotational speeds of the primary pulley 21 and the engine increase rapidly. The degree of opening of the flow control valve 64 is controlled while maximizing.
[0028]
During the period from the first time point T ₁ to the second time point T ₂ when the primary pulley 21 is increasing in rotation speed, an increase rate m of the actual rotation speed W _Pr of the primary pulley 21 is calculated. Based on the actual rotational speed W _P2 of the primary pulley 21 obtained at the second time point T ₂ , the actual rotational speed W _Pr of the primary pulley 21 at the subsequent third time point T ₃ is estimated. Then, the provisional target rotation speed W _PT1 is set by adding the first correction amount W _PA and the second correction amount W _th to the estimated rotation speed W _P3 . The temporary target rotational speed W _PT1 is the true target rotational speed W _PT0 the difference between the temporary target rotational speed W _PT1 is within a first predetermined value α of the (fourth time point T ₄₎ increase the correction amount W _PA Change to a smaller correction amount W _PA ′ to reduce the temporary target rotational speed W _PT1 .
[0029]
First, the case where a constant large opening θ _th1 is maintained after the throttle opening θ _th is increased (see the solid line in FIG. 3B) will be described. The target rotational speed setting means 52 starts the kick-down control (initial time point). Since the true target rotational speed W _PT0 is used as the target rotational speed W _PT of the primary pulley 21 from the time T ₀ to the third time point T _{3, the} rotation of the engine 1 and the primary pulley 21 rapidly increases (during this time) Then, since the vehicle speed and the rotation of the secondary pulley 22 do not change), since the temporary target rotational speed W _PT1 is controlled using the target rotational speed W _PT from the third time point T ₃ to the fifth time point T ₅ , the engine 1 and The rotation of the primary pulley 21 and the vehicle speed and the rotation of the secondary pulley 22 both increase, thereby realizing a rapid increase in the engine speed during kickdown and the subsequent vehicle speed. It is possible to carry out the increase of the time without delaying.
[0030]
When the difference becomes sufficiently smaller than the first predetermined value α or close to 0 (fifth time point T ₅ ), the true target rotational speed W _PT0 is again used as the target rotational speed W _PT. However, since the correction amount W _PA for calculating the temporary target rotational speed W _PT1 is changed to the correction amount W _PA ′ with a small increase rate from the fourth time point, when the fifth time point T ₅ is reached, temporary target rotational speed W _PT1 becomes to increase very slowly, overshoot of the actual rotational speed W _Pr when returning the target rotational speed W _PT from the temporary target rotational speed W _PT1 to the true target rotational speed W _PT0 is Thus, the actual rotation speed W _Pr quickly approaches the true target rotation speed W _PT0 . Therefore, driving feeling can be improved.
[0031]
Meanwhile, after the throttle opening theta _th is increased in large opening theta _th1, when increased to further large opening theta _th2 at T ₆ [bold line see the broken line in shown in FIG. 3 (b)], the second correction amount W _th same time Accordingly, the true target rotational speed W _PT0 and the temporary target rotational speed W _PT1 also increase in accordance with this as shown by the thin broken lines W _PT0 ′ and W _PT1 ′ in FIG. Further, when the throttle opening θ _th increases to the large opening θ _th1 and then decreases to the opening θ _th3 (see the thick dashed line in FIG. 3B) at time T ₇ , the second correction amount W _{th is} simultaneously _achieved. Accordingly, the true target rotational speed W _PT0 and the temporary target rotational speed W _PT1 also decrease as shown by the two-dot chain thin lines W _PT0 ″ and W _PT1 ″ in FIG.
[0032]
Thus, since the second correction amount W _th that determines the temporary target rotational speed is changed according to the throttle opening θ _th [the degree of acceleration intention (load information) of the driver], the answer is based on the degree of acceleration intention of the driver. And acceleration feeling can be further improved. For example, if the driver seeks greater acceleration after the acceleration command (time T ₀ ′) and increases the throttle opening θ _th , the rotation of the engine 1, the primary pulley 21 and the vehicle speed, Both the rotation and the speed will rise more quickly, and the acceleration of the vehicle is promoted and the driver's acceleration request can be met. Further, if the throttle opening _θth is decreased in order to weaken the acceleration after the acceleration command (time T ₀ ′), the rotation of the engine 1 and the primary pulley 21 and the vehicle speed and the speed of the secondary pulley 22 are accordingly increased. Ascending with the rotation becomes slow, the acceleration of the vehicle is suppressed, and the driver's acceleration reduction request can be answered.
[0033]
The present invention is not limited to the above-described embodiment. For example, the increase characteristics of the correction amounts W _PA , W _PA ′, W _th , W _th ′ are linear as shown in FIGS. Not limited to this, various characteristics can be set. Also, other setting forms such as making the first predetermined value α variable according to the true target rotational speed W _PT0 are also conceivable. In this embodiment, when the difference W _PD becomes close to 0, the target rotational speed W _PT is returned from the temporary target rotational speed W _PT1 to the true target rotational speed W _PT0 , but the difference W _PD is When 0 is reached, the target rotational speed W _PT0 may be restored. Further, if not to overshoot of the actual rotational speed W _Pr special problems when returning the target rotational speed W _PT from the temporary target rotational speed W _PT1 to the true target rotational speed W _PT0, the first correction at T ₃ The control for reducing the amount W _PA to the correction amount W _PA ′ may be omitted.
[0034]
【The invention's effect】
As described above in detail, according to the transmission control device for a continuously variable transmission for a vehicle according to the present invention, the provision of the temporary target rotational speed allows the second rotating member and the vehicle speed to be increased rapidly, and the load information is included. By correcting the temporary target rotational speed accordingly, the driver's intention to accelerate can be reflected in the vehicle acceleration control based on the temporary target rotational speed, and the acceleration feeling can be further improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a shift control device for a continuously variable transmission for a vehicle according to an embodiment of the present invention.
2A and 2B are diagrams for explaining a continuously variable transmission for a vehicle according to an embodiment of the present invention, in which FIG. 2A is a schematic configuration diagram of a drive system, and FIG. 2B is a configuration diagram of a continuously variable transmission. .
3A and 3B are diagrams showing a control example according to an embodiment of the present invention, in which FIG. 3A is a diagram showing a primary pulley rotation speed, and FIG. 3B is a diagram showing a throttle opening degree.
FIG. 4 is a diagram showing correction characteristics according to an embodiment of the present invention.
5A and 5B are diagrams showing correction characteristics according to an embodiment of the present invention, where FIG. 5A is a diagram of the present embodiment, and FIGS. 5B and 5C are diagrams showing modifications thereof.
[Explanation of symbols]
1 engine (internal combustion engine)
20 Belt type continuously variable transmission (CVT) as transmission
21 First rotating member (primary pulley)
22 Second rotating member (secondary pulley)
23 Belt (intervening member)
51 Shift control means 52 Target rotation speed setting means 53 Kick down determination means 54 Primary pulley rotation control means (first rotation member control means)
55 Primary pulley rotation speed estimation means (rotation speed estimation means)
56 Temporary target rotational speed setting means

Claims (1)

For a vehicle comprising a first rotating member connected to the output side of the engine, a second rotating member connected to the drive wheel side of the vehicle, and an interposed member for transmitting power between the first and second rotating members. A continuously variable transmission and shift control means for controlling the gear ratio of the continuously variable transmission by changing the rotation speed ratio of the first and second rotating members,
The shift control means includes target rotation speed setting means for setting a target rotation speed of the first rotation member based on load information and vehicle speed information of the engine,
Kick down determination means for determining kick down from the load information;
The rate of increase in the actual rotational speed of the first rotating member from the first time point after the kick-down determination to the second time point after the first time point is calculated, and the time after the second time point is calculated from the increase rate. A rotational speed estimating means for estimating the rotational speed of the first rotating member at the third time point;
Temporary target rotation speed setting means for setting a temporary target rotation speed based on the rotation speed estimated by the rotation speed estimation means, the elapsed time from the second time point, and the load information; and the target at the second time point A continuously variable transmission for a vehicle, comprising: a switching means for switching from the target rotational speed set by the rotational speed setting means to the temporary target rotational speed set by the temporary target rotational speed setting means. Shift control device.

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