JP2000039063A - Speed change control device for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operability by suppressing the occurrence of hunting of the number of revolutions of engine during starting. SOLUTION: The target change gear ratio of a continuously variable transmission 10 responding to an operation state is computed and based on a deviation between an actual change gear ratio and a target change gear ratio, a step motor 4 is driven so that the actual change gear ratio coincides with the target change gear ratio. A so formed speed change controller 61 performs feedback control and increases feedback gains c0, c1, and c2 are increased during starting of a vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a shift control device for a continuously variable transmission.

[0002]

2. Description of the Related Art Continuously variable transmissions used in vehicles include:
Conventionally, continuously variable transmissions such as a V-belt type and a toroidal type have been known.
There is one disclosed in Japanese Patent Application Laid-Open No. 7-98323 proposed by the present applicant.

[0003] When the speed change control of a toroidal-type continuously variable transmission is performed by feedback, the feedback gain is inversely proportional to the output shaft speed No or the relationship between the output shaft speed No and the tilt angle φ of the power roller. It changes according to.

In the case of a toroidal-type continuously variable transmission, the relationship between the displacement amount y of the power roller (axial displacement amount of the trunnion) which determines the shift response and the tilting speed (shift speed) dφ / dt is expressed as follows.

[0005]

(Equation 1)

[0006] In consideration of the fact that the condition is approximately established, an inverse characteristic is given to the feedback gain so as to always realize a constant shift performance.

However, in the above equation (1), θ, η, R: constant No. determined according to the size of the speed change mechanism;

In such a continuously variable transmission, the shift characteristics change in accordance with the operation state. For example, in order to realize a constant shift characteristic, a feedback gain schedule is established, and a constant shift is performed regardless of the operation state. Responsiveness is ensured.

[0009]

However, in the above-described conventional example, at the time of starting when the target gear ratio changes abruptly, etc., as shown in FIG.
The actual speed ratio is greatly delayed from the target speed ratio, and this delay causes a problem that the engine speed Ne hunts and the drivability is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to improve operability by suppressing hunting of the engine speed which occurs at the time of starting.

[0011]

According to a first aspect of the present invention, there is provided a continuously variable transmission for continuously changing a speed ratio via an actuator, and a target speed ratio of the continuously variable transmission is calculated in accordance with an operation state. And a feedback control means for driving the actuator based on a deviation between the actual speed ratio and the target speed ratio so that the actual speed ratio matches the target speed ratio. Wherein the feedback control means includes start detection means for detecting start of the vehicle, and feedback gain setting means for determining a feedback gain of the feedback control means in accordance with a driving state, and when the start of the vehicle is detected. And increase the feedback gain.

In a second aspect based on the first aspect, the feedback gain setting means includes at least a normal speed shift gain map and a start gain map. Switch to the gain map for

In a third aspect based on the first aspect, the feedback gain setting means includes a variable table for determining a plurality of variables according to an operating state, and a plurality of variables determined from the variable table. Has a gain map for determining a feedback gain corresponding to, one of the variable tables is provided with at least a variable table for normal shift and a variable table for starting, the starting variable table at the time of the start Switch.

In a fourth aspect based on the first aspect, the feedback gain setting means includes a gain map in which a gain according to an operating state is stored in advance, and the feedback map corresponds to a start of the gain map. Set only the feedback gain of the area large.

In a fifth aspect based on the fourth aspect, the start detecting means includes a depression amount detecting means for detecting a depressed state of the accelerator pedal, and when the accelerator pedal is depressed other than when starting. The shift control device for a continuously variable transmission according to claim 1, wherein the control device inhibits an increase in a feedback gain.

In a sixth aspect based on the first aspect, the continuously variable transmission is a toroidal type having a mechanical feedback mechanism, and the feedback control means includes a mechanical feedback component. A canceling means is provided for adding to the feedback control amount to cancel out, and when the start of the vehicle is detected, the gain of the canceling means is increased.

According to a seventh aspect of the present invention, there is provided a continuously variable transmission which continuously changes the gear ratio via an actuator, and calculates a target gear ratio of the continuously variable transmission according to an operating state, A feedback control unit that drives the actuator based on a deviation between the gear ratio and the target gear ratio so that an actual gear ratio matches the target gear ratio. The means has target speed ratio setting means for setting a target speed ratio in accordance with a driving state of the vehicle. The target speed ratio setting means includes a shift map for a normal speed change and a start in which a change in the speed ratio is set smoothly. And a shift map for starting is selected when the vehicle starts moving.

[0018]

Therefore, in the first invention, since the feedback gain is increased only when the vehicle starts, the gear is shifted from the lowest gear ratio to the Hi gear when the vehicle starts. As a result, the actual speed ratio can be made to follow the target speed ratio, and the hunting of the engine speed as shown in the conventional example can be suppressed, so that the drivability of the vehicle having the continuously variable transmission can be improved. Since the feedback gain is reduced during normal driving, the excessive change in the gear ratio caused by the large feedback gain is reliably suppressed,
It is possible to realize a quick shift immediately after starting.

According to a second aspect of the present invention, the feedback gain is determined by one of a gain map for normal shifting and a gain map for starting, so that a large gain at the time of starting and a low gain for normal running are obtained. Can be easily switched.

In a third aspect of the present invention, a gain map for determining a feedback gain determines a feedback gain in accordance with a variable obtained from a plurality of variable tables in accordance with an operating state, and sets a variable table for normal driving in a variable table. Since the start table is provided, it is possible to easily switch between a large gain at the start and a low gain for normal running by changing the variables.

Further, in the fourth invention, since only the feedback gain in the region corresponding to the start of the gain map is set to be large, the feedback gain at the time of start and the feedback for normal running can be increased with a single gain map. The gain can be reduced at the same time.

According to the fifth aspect of the present invention, when the accelerator pedal is depressed other than at the time of starting, an increase in the feedback gain is prohibited. In the case where the reduction of the feedback gain for normal running is compatible, it is possible to prevent the feedback gain from being changed for starting while running at a low vehicle speed.

According to a sixth aspect of the present invention, the continuously variable transmission is of a toroidal type having a mechanical feedback mechanism, and the gain of the canceling means for adding the mechanical feedback to the feedback control amount to cancel out increases only at the start. By doing so, the actual speed ratio can be made to follow the target speed ratio in response to a sudden change in the speed ratio, and hunting of the engine speed as in the conventional example can be suppressed.

According to a seventh aspect of the present invention, a map for setting a target speed ratio in accordance with a driving state of a vehicle includes a speed change map for a normal speed change and a start speed change map for setting a change in the speed ratio smoothly. By selecting a shift map for starting when the vehicle starts, it is possible to suppress the actual speed ratio from delaying from the target value, and to prevent hunting of the engine speed Ne as in the conventional example. Becomes possible.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an example in which the present invention is applied to a case where a toroidal type similar to the conventional example is employed as the continuously variable transmission 10.

The continuously variable transmission 10 is connected to the engine 11 via a torque converter 12 provided with a lock-up mechanism L / U on the input shaft 13 side, while the output shaft side (output disk side) is not shown. The transmission mechanism and the mechanical feedback mechanism of the toroidal-type continuously variable transmission 10 are connected to the wheels, and are configured in the same manner as in the conventional example, and the step motor 4 (actuator) is not shown according to a command from the transmission control controller 61. The shift is performed by driving the shift control valve.

The shift control controller 61 is mainly composed of a microcomputer, and includes a shift switch 2.
In the case of the automatic transmission mode in which 0 (or the inhibitor switch) is in the D range or the L range, the throttle opening TVO (or the amount of depression of the accelerator pedal) detected by the throttle opening sensor 62 and the output of the continuously variable transmission 10. Based on the vehicle speed VSP from the vehicle speed sensor 63 disposed on the shaft side and the rotation speed Ni of the input shaft 13 of the continuously variable transmission 10 detected by the input shaft rotation sensor 64, the target inclination in accordance with the driving state of the vehicle is determined. While the shift angle φmap (synonymous with the target gear ratio to be finally shifted; the gear ratio and the tilt angle are also synonymous with each other) is calculated, the shift switch 20 is set to “+” or Upshift switch 21 of "-",
In the manual mode on the downshift switch 22 side, one of a plurality of preset target tilt angles (or shift speeds) is selected according to the driver's operation, and the target target tilt angle φmap is set to a predetermined value. Fix within the conditions.

Further, based on the oil temperature Temp of the continuously variable transmission 10 detected by the oil temperature sensor 65 and the oil pressure (line pressure) PL of the continuously variable transmission 10 detected by the oil pressure sensor, PID control (proportional or integral) , Differential control) gains c ₀ , c ₁ , c ₂
And calculates a shift command value such that the actual tilt angle φ of the continuously variable transmission 10 matches the target tilt angle φt, that is, the number of steps STP, and instructs the step motor 4. Note that the vehicle speed sensor 63 indicates the output shaft rotation speed N of the continuously variable transmission 10.
The value obtained by multiplying o by a predetermined constant is output as the vehicle speed VSP.

As shown in FIG. 2, an outline of the shift control by the shift controller 61 is an actual tilt angle φ (= actual gear ratio), that is, a tilt angle for obtaining the tilt angle φ of the power roller 3. Calculation unit 71, throttle opening TVO and vehicle speed VS
A target tilt angle calculating section (not shown) for calculating a target tilt angle φmap according to P; a y displacement estimating section 72 for calculating an offset amount y of the power roller 3;
3, mainly composed of an integrator 74 and a step converter 75, and performs multiplication of various gains and addition and subtraction of various signals.

First, the tilt angle calculator 71 calculates the output shaft speed No and the input shaft speed N obtained by dividing the vehicle speed VSP by a predetermined constant.
The actual tilt angle φ of the actual power roller is determined based on the ratio of i.

The y displacement estimating section 72 estimates the offset y of the power roller 3 in the same manner as in Japanese Patent Application No. 7-71495 proposed by the present applicant. Note that the offset amount y may be obtained from a differential value of the tilt angle φ of the power roller 3.

The gain calculator 73 determines each gain of the PID control, that is, the integral gain c ₀ , the proportional gain c ₁ , and the differential gain c ₂ by the following equation.

[0034]

(Equation 2)

That is, the transfer function according to the characteristics of the toroidal type continuously variable transmission 10 is expressed by the following equation.

[0036]

(Equation 3)

Therefore, the above equation (3) coincides with a linear system, and the integral gain c ₀ , the proportional gain c ₁ , and the differential gain c ₂ have a characteristic represented by the following equation (4). Is determined by the above equation (2).

[0038]

(Equation 4)

Here, the predetermined constants λ ₁ , λ ₂ , λ ₃ are coefficients representing the poles of the transfer function, and these constants must be positive real numbers.

That is, if any of the constants λ ₁ , λ ₂ , λ ₃ is negative, the system becomes unstable and cannot be controlled to the target tilt angle, and the constants λ ₁ , λ 3 If either ₂ or λ ₃ is an imaginary number, the feedback characteristic becomes oscillating, and hunting that adversely affects drivability occurs.

The process for calculating the gain when the shift control controller 61 is configured as shown in FIG. 2, that is, the above equation (2) will be described below.

The shift control controller 61 has a cam canceling feedback 70 for adding the action of the mechanical feedback precess cam to the control command value, so that the characteristic of the transfer function shown in the above equation (3) is as follows. 5) It becomes equivalent to the characteristic shown in the equation.

[0043]

(Equation 5)

The cam canceling feedback 70
Is to cancel the mechanical feedback amount for feeding back the tilt angle φ.

As shown in FIG. 2, the deviation e between the target tilt angle and the actual tilt angle φ calculated by the tilt angle calculator 71 and the deviation e calculated by the integrator 74 are calculated. Integral value
The value obtained by multiplying the value of the offset amount y obtained by the y displacement estimating unit 72 by the gain c ₂ is subtracted from the value obtained by multiplying the proportional gain c ₁ and the integral gain c ₀ and then adding. When the value from the cam canceling feedback unit 70 is added to this value, the transfer function from the target tilt angle to the actual tilt angle is expressed by the following equation (6). It is widely known.

[0046]

(Equation 6)

In order for this equation (6) to coincide with the above equation (4), as shown in the above equation (2), each gain c ₀ ,
c ₁ and c ₂ must be determined. When the cam cancellation feedback 70 is not used, the following equation (7) is used instead of the above equation (2), and the effect of canceling the mechanical feedback is given to the proportional gain c ₁ , which is equivalent. .

[0048]

(Equation 7)

Here, the toroidal type continuously variable transmission 10 is a linear system, but g and f, which are constants, are actually:
Although it is a nonlinear system that changes depending on various factors,
Even in a nonlinear system, it is widely known as a gain schedule method in control theory that good control can be performed by switching a control system linearly approximated under a specific operating condition according to a change in condition. By the way.

That is, g and f are obtained under the respective operating conditions, and the gains c ₀ , c ₁ , and c ₂ are calculated in advance by the above equations (2) to (7) for each of the conditions. The gains c ₀ , c ₁ , and c ₂ , which are obtained in advance, are switched according to changes in operating conditions.

Since g used in the equation (2) and thereafter is a gain from the valve opening x of the transmission control valve (the gap between the sleeve 5 and the spool 5) to the offset y of the power roller 3, the hydraulic system (Transmission mechanism and mechanical feedback system).

Further, f used in the above equation (2) and subsequent equations is used.
Is obtained by substituting constants (θ, η, R) determined from the structure of the toroidal-type continuously variable transmission 10 given by the above equation (1), the tilt angle φ, and the output disk rotation speed No. Value.

Therefore, the gain calculating section 73 shown in FIG. 2 includes the oil temperature Temp detected by the oil temperature sensor 65 affecting the hydraulic system and the oil pressure PL detected by the oil pressure sensor 66.
And the actual tilt angle φ obtained by the tilt angle calculation unit 71 and the respective signals of the vehicle speed VSP detected by the vehicle speed sensor 63 which are equivalent to the number of revolutions of the output disk, are input in advance for each gain by an experiment or the like. The gains c ₀ , c ₁ , and c ₂ are determined by referring to the set gain map based on these signals as described later.

Here, as shown in FIG. 5, a table (or map) for determining each gain is obtained from g_table for obtaining a variable g (i) from the oil temperature Temp and the hydraulic pressure PL, and from the vehicle speed VSP and the tilt angle φ. F_ta for finding the variable f (i)
ble and variables f (i) and g (i) to obtain a gain array Gn.
It is composed of three tables of gain_table for obtaining n, and the gain array Gnn stores the respective feedback gains c ₀ , c ₁ , c ₂ as Gnn = (c ₀ , c ₁ , c ₂ ). ing.

In the gain_table, there are set gain_table1 used at the time of starting, gain_table1 used at the time of the manual mode, and gain_table3 used at the time of the normal speed change. The selection is made according to the state as described later.

The gain_table1 for starting has a relatively higher feedback gain than the gain_table3 for normal shifting, and the gain_table2 for manual mode is set almost the same as the gain for normal shifting. The gain is not changed when starting.

Therefore, according to the operating state, the variable g is determined from the oil temperature Temp and the hydraulic pressure PL of the continuously variable transmission 10, and the variable f is determined from the vehicle speed VSP and the tilt angle φ, and then the variables f and g are determined.
Thus, each of the gains can be determined by determining the gain array Gnn by selecting the gain_tables 1 to 3 according to the operating state.

The deviation e, the integral value of the deviation e (output of the integrator 74), and the offset amount y obtained by multiplying the gains c ₀ , c ₁ , and c ₂ obtained by the gain calculator 73 are shown in FIG. As shown, the value is added or subtracted and then input as a command value to the step converter 75.
After calculating the valve displacement amount (opening amount) of the shift control valve for eliminating the deviation e between the target tilt angle and the actual tilt angle, calculating the number of steps STP corresponding to the valve displacement amount, and then instructing the step motor 4 I do.

Next, the shift control performed by the shift controller 61 will be described in detail with reference to the flowcharts of FIGS. FIG. 3 shows a main routine of the shift control, and FIG. 4 shows a gain setting subroutine.

First, in step S 1 of FIG. 3, the vehicle speed VSP is obtained from the vehicle speed sensor 63, the throttle opening TVO from the throttle opening sensor 62, the input shaft rotation speed Ni from the input shaft rotation speed sensor 64, and the oil temperature sensor 65. From oil temperature Tem
p, and the oil pressure (line pressure) PL is read from the oil pressure sensor 66, respectively.

In step S2, the output shaft rotation speed No is obtained by dividing the vehicle speed VSP by a predetermined constant A, and the actual power roller speed is obtained from the ratio of the input / output shaft rotation speeds Ni and No and a preset map. The tilt angle φ is calculated.

Next, in step S3, the target input shaft speed tNi is obtained from the shift map as shown in FIG. 10 from the vehicle speed VSP and the throttle opening TVO, and the target input shaft speed tNi is divided by the output shaft speed No. Target tilt angle φma based on
Calculate p.

In step S4, the driving state of the vehicle, that is, vehicle speed VSP, actual tilt angle φ, oil temperature Temp, hydraulic pressure PL
, The feedback gains c ₀ , c ₁ , c ₂ are calculated, and in step S5, the step motor 4
The target tilt angle φt is calculated in consideration of the operation state such as the response characteristics of the above.

Then, in step S6, step S4
The feedback control amount is obtained based on the feedback gain obtained in the above, the actual tilt angle φ, and the attained target tilt angle φmap. In step S7, the target tilt angle φt is based on the command value compensated by the feedback control amount. , The control amount STP of the step motor 4 is calculated, and the
Outputs the control amount STP.

Next, the gain setting process performed in step S4 will be described in detail with reference to the flowchart of FIG.

First, in step S11, it is determined whether or not the vehicle is substantially stopped based on the vehicle speed VSP and the throttle opening TVO. That is, when the vehicle speed VSP is the predetermined value V
If the throttle opening TVO is less than or equal to 1 and the tilt angle φ corresponding to the lowest Low speed ratio (for example, the maximum Low is obtained even when TVO = 1/8), it is determined that the vehicle is in a stopped state. While the process proceeds to step S12, otherwise, it is determined that the vehicle is traveling and the process proceeds to step S16.

In step S12 where it is determined that the vehicle is in the stopped state, it is determined whether or not the mode is the manual mode based on the state of the shift switch 20 in FIG. 1. If the mode is the manual mode, the process proceeds to step S14. Of the gain maps shown, gain_tab for manual mode
While selecting le2, if it is an automatic shift mode such as D range or L range, the process proceeds to step S13,
The gain_table1 for starting shown in FIG.

Then, in step S15, the start flag Fst indicating the start state is set to 1, and then in step S2
Proceeding to 1, the calculation of each feedback gain is performed.

On the other hand, in step S16 where it is determined that the vehicle is traveling in the determination of step S11, the start flag Fst is set to 0.
Is determined, and if it is 0, the process proceeds directly to the calculation of the gain in step S20. On the other hand, if Fst = 1, it is the case immediately after the start, and therefore, step S17 is performed.
Then, it is determined whether the vehicle speed VSP is equal to or lower than a predetermined value V2.

When the vehicle speed VSP is less than the predetermined value V2,
Since it is still the area where the gain map for starting is necessary immediately after the start, the process directly proceeds to step S21, and the gain is calculated by the gain table for starting as in the previous time.

On the other hand, the vehicle speed VS is determined in step S17.
If P is equal to or greater than the predetermined value V2, it can be determined that the vehicle has shifted from the start to the normal running. Therefore, the process proceeds to step S18, where the start flag Fst is cleared to 0, and the shift mode is determined in step S19. Mode
Proceeding to step S21 as it is to calculate the gain, if it is a normal automatic shift mode, proceeding to step S20 to display the gain map for the gain_table for starting.
After switching from 1 to gain_table3 for normal running, the process proceeds to step S21, where each feedback gain is calculated based on the feedback gain for shifting, and then the process returns to the routine of FIG.

Therefore, in the predetermined stop state,
The gain map gain_table1 for starting is selected, and the gain is set high.

That is, as shown in the map of FIG. 10, when the vehicle starts, the vehicle is propelled from the lowest speed ratio, and when the vehicle speed VSP exceeds a predetermined value, the throttle opening T
The shift is started according to VO. Then, as shown in FIG. 6, at the start of the shift immediately after the start, the start gain_
Since the feedback gain is set to be higher than that during the normal gear shift by table1, the actual tilt angle φ does not greatly delay from the target tilt angle φt, and the actual rotation angle φ does not exceed the target rotation angle φt. Hunting can be suppressed, and the drivability of the vehicle including the continuously variable transmission 10 can be greatly improved.

When the vehicle speed VSP exceeds the predetermined value V2, the gain map is changed to the gain_table for normal shifting.
3, the feedback gain is reduced, so that it is possible to realize a quick shift immediately after the start, while surely preventing an excessive change in the tilt angle φ during the normal shift.

FIG. 7 shows a second embodiment, in which the first
The switching of the gain map according to the embodiment is performed by switching a table f_Table for selecting a variable f according to the operating state, and the other points are the same as those in the first embodiment.

The variable f (i) is f_Table for starting.
1, f_Table2 for manual mode, and f_Table3 for normal speed. Then, variables f (i) and g according to the operating state
(I) Gain that determines each feedback gain from
_Table is set to one similar to that for the normal speed change of the first embodiment.

Steps S13, S14, S in FIG.
At 20, the variable tables f_table1 to f_table1 to 3 are switched instead of the gain map.

Here, f_table1 for starting is stored more than f_Table3 for normal shifting, and f (i) is stored.
Is set to be large so that the feedback gain set by gain_Table becomes large. The variable f (i) of the f_Table2 for the manual mode is set in substantially the same manner as the f_Table3 for the normal speed change.

Therefore, immediately after starting, f_tabl
By e1, the variable f (i) is changed to f_Tab for normal shift.
Since it is set to be larger than le3, gain_Tab
The gain array Gnn obtained from le also increases. Then, when the shift is started, the hunting of the engine speed Ne can be suppressed by the feedback gain larger than that at the time of the normal shift, similarly to the first embodiment. Drivability of the equipped vehicle can be greatly improved.

When the vehicle speed VSP shifts to the normal running exceeding the predetermined value V2, the vehicle is switched from the starting f_Table1 to the normal shifting f_Table3, and the gain is reduced. Thus, it is possible to realize a quick shift immediately after the vehicle starts, while suppressing the occurrence of a large fluctuation.

In the first or second embodiment, the gain map or the variable table for determining each feedback gain is changed at the time of starting. However, as shown in FIG. 2, the tilt angle of the power roller is offset. Even if the cam canceling gain is increased only at the time of the start, the hunting of the engine speed Ne can be suppressed.

The rate of change of the throttle opening dTVO
And the amount of change ΔTVO is detected to determine a further step downshift, and in the case of a further step downshift (kick down), the same gain as in the normal shift is used, so that the vehicle can be driven during a period other than the start. The shift characteristic can be prevented from changing.

FIG. 8 shows a third embodiment, in which the first embodiment is used.
Instead of switching the gain map of the embodiment, a single gain map is used to increase the feedback gain at the time of starting and reduce the feedback gain at the time of normal shifting.

The gain map shown in FIG. 8 is for obtaining the gain array Gnn from the variables f (i) and g (i) in the same manner as described above.

In a region where f (i) used in the driving state at the time of starting is small, a feedback gain designed with β dB having a small gain margin as compared with other regions is set, while f (i) other than at the time of starting is set. In a region where (i) becomes large, a feedback gain designed with αdB having a relatively large gain margin is set, similar to the gain_table2 for the normal speed change.

Therefore, since the feedback gain in the area of the gain map used at the time of starting is set to be large, the variable f (i) is increased while preventing the hunting of the engine speed Ne during the shift immediately after starting. During traveling, the feedback gain is set to be small, so that it is possible to realize a quick shift immediately after starting and a stable characteristic during normal shift, while preventing an increase in the number of gain maps.

In this case, the change rate dTVO of the throttle opening and the change amount ΔTVO are detected, and the change rate dTVO is detected.
If the VO and the change amount ΔTVO exceed a predetermined value, it is determined that the stepped-up shift is determined, and if the increase in the feedback gain is prohibited, when the stepped-up shift is performed at a low vehicle speed, the feedback gain is switched to the starting feedback gain. Can be prevented.

FIG. 9 shows a fourth embodiment, in which the second embodiment
Instead of switching the variable tables of the embodiment, the feedback variable at the time of starting and the feedback gain at the time of normal shifting are reduced by a single variable table f_Table.

As shown in FIG. 9, the magnitude of the variable f (i) is determined by a theoretical formula or the like obtained in advance according to the magnitude of the vehicle speed VSP and the magnitude of the tilt angle φ. The driving range used when the vehicle speed VSP is small and the tilt angle φ
Is on the low side, the value of f (i) to be stored is set to be larger than the theoretical formula in a predetermined area used at the time of starting, and while the feedback gain set by gain_Table is increased, normal driving is performed. In other areas used inside, the value of f (i) to be stored is set according to a theoretical formula, and the feedback gain set by gain_Table is reduced as compared with the area for starting. Thus, it is possible to realize quick shifting immediately after starting and stable characteristics during normal shifting without increasing the number of variable tables.

FIG. 10 and FIG. 11 show a fifth embodiment, in which a shift map for obtaining an attained target tilt angle gear ratio φmap is used instead of switching of the gain map of the first embodiment. The switching is performed at the time of normal gear shifting.

At the time of normal gear shifting, the attained target tilt angle φmap is set by the map of FIG. 10, while when the operating state is the same as that at the time of switching the gain map of the first embodiment, the shift map is switched to that of FIG. .

When the vehicle is started using the shift map for normal shifting shown in FIG. 10, the vehicle speed VSP and the target input shaft rotation speed tNi increase along the lowest line at which the speed ratio becomes maximum, and the vehicle speed VSP is reduced. When the shift start point is reached in accordance with the opening TVO, the vehicle speed VSP and the target input shaft rotational speed tN are set along a diagram set for each throttle opening TVO.
i changes, but in this case, the gear ratio at the shift start point = the tilt angle φ (the tilt in the diagram in the figure) changes abruptly, so that the actual tilt angle is the same as in the conventional example. φ is greatly delayed from the target value, and hunting of the engine speed Ne occurs.

Therefore, as shown in FIG. 11, in the shift immediately after the start, the change point of the gear ratio is set in a smooth arc shape, so that the target tilt angle φmap obtained from the map is obtained.
In addition, the actual tilt angle φ can be easily approximated to suppress the delay from the target value, and it is possible to prevent hunting of the engine speed Ne as in the conventional example.

In the first to fourth embodiments, the gain map or the variable table for determining each feedback gain is changed. However, as shown in FIG. 2, a cam for canceling the tilt angle feedback of the power roller. Even if the offset gain is increased only at the start,
Hunting of the engine speed Ne can be suppressed.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a shift control device for a continuously variable transmission, showing one embodiment of the present invention.

FIG. 2 is a block diagram of a transmission control controller.

FIG. 3 is a flowchart illustrating an example of a shift control.

FIG. 4 is a flowchart illustrating an example of control performed by a gain calculator.

FIG. 5 is a conceptual diagram showing an example of a variable table and a gain map.

FIG. 6 is a graph showing a relationship between a speed change ratio (tilt angle) at start and an engine speed.

FIG. 7 is a conceptual diagram illustrating an example of a variable table and a gain map according to the second embodiment.

FIG. 8 is a conceptual diagram illustrating an example of a gain map according to the third embodiment.

FIG. 9 is a conceptual diagram illustrating an example of a variable f_Table according to the fourth embodiment.

FIG. 10 shows a fifth embodiment and is a shift map for normal shift.

FIG. 11 is also a shift map for starting.

FIG. 12 is a graph showing a conventional example and showing a relationship between a speed change ratio (tilt angle) at start and an engine speed.

[Explanation of symbols]

 Reference Signs List 4 step motor 10 stepless transmission 61 shift control controller 62 throttle opening sensor 63 vehicle speed sensor 64 input shaft rotation sensor 65 oil temperature sensor 66 oil pressure sensor 70 cam canceling feedback unit 71 tilt angle calculation unit 72 y displacement estimation unit 73 gain Calculation unit 74 Integrator 75 Step conversion unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasushi Narita 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Inside Nissan Motor Co., Ltd. (72) Inventor Kazuhiro Takeda 2 Takaracho, Kanagawa-ku, Yokohama City, Kanagawa Nissan Motor Co., Ltd. F Terms (reference) 3J052 AA11 AA20 CA21 CB01 DB01 FA06 GC03 GC23 GC43 GC44 GC46 HA13 LA01

Claims (7)

[Claims] 1. A continuously variable transmission that continuously changes a gear ratio via an actuator, a target gear ratio of the continuously variable transmission is calculated in accordance with an operating state, and an actual gear ratio and a target gear ratio are calculated. And a feedback control means for driving the actuator such that an actual gear ratio matches a target gear ratio based on the deviation of the vehicle speed. And a feedback gain setting means for determining a feedback gain of the feedback control means according to a driving state, wherein when the start of the vehicle is detected, the feedback gain is increased. Transmission control device for a continuously variable transmission. 2. The feedback gain setting means according to claim 1, wherein
2. The vehicle according to claim 1, further comprising at least a gain map for normal shifting and a gain map for starting, and switching to the gain map for starting when said starting is detected.
3. The shift control device for a continuously variable transmission according to claim 1. 3. The feedback gain setting means,
A variable table that determines a plurality of variables according to the operating state, and a gain map that determines a feedback gain corresponding to the plurality of variables determined from these variable tables, one of the variable tables includes at least The shift control device for a continuously variable transmission according to claim 1, wherein a variable table for a normal shift and a variable table for a start are provided, and the variable table for the start is switched at the time of the start. 4. The feedback gain setting means,
2. The continuously variable transmission according to claim 1, further comprising: a gain map in which a gain according to an operation state is stored in advance, wherein only a feedback gain in a region corresponding to the start of the gain map is set large. Transmission control device. 5. The start detecting means includes means for detecting a depressed state of an accelerator pedal, and prohibits an increase in a feedback gain when the accelerator pedal is depressed other than when starting. A shift control device for a continuously variable transmission according to claim 4. 6. The continuously variable transmission is of a toroidal type having a mechanical feedback mechanism, and the feedback control means is provided with a canceling means for adding a mechanical feedback component to a feedback control amount and canceling the feedback control amount. The shift control device for a continuously variable transmission according to claim 1, wherein the gain of the canceling means is increased when the start of the vehicle is detected. 7. A continuously variable transmission that continuously changes a gear ratio via an actuator, and calculates a target gear ratio of the continuously variable transmission in accordance with an operation state, and calculates an actual gear ratio and a target gear ratio. And a feedback control means for driving the actuator so that an actual gear ratio matches a target gear ratio based on the deviation of the speed change ratio of the continuously variable transmission. It has a target speed ratio setting means for setting a target speed ratio according to the state, and the target speed ratio setting means includes a speed change map for a normal speed change and a start speed change map for setting a change in the speed ratio smoothly. A shift control device for a continuously variable transmission, wherein a shift map for starting is selected when the vehicle starts.