JP3173668B2 - Shift control device for continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for a continuously variable transmission, and more particularly to a vehicle equipped with a continuously variable transmission that prevents a decrease in fuel consumption rate and an increase in vibration and noise when the vehicle starts from a stop. Also, the present invention relates to a shift control device for a continuously variable transmission that can prevent engine stall and improve starting feeling.

[0002]

2. Description of the Related Art A transmission mounted on a vehicle includes a gear transmission in which a gear ratio is changed stepwise by switching gear trains, and a transmission in which the rotation radius of a belt wound around two pulleys is increased or decreased. There is a continuously variable transmission that continuously changes the ratio.

A continuously variable transmission is provided with a drive side pulley and a driven side pulley, and a belt is wound around these pulleys, and the width of a groove formed between each pulley portion of both pulleys is increased or decreased. The gear ratio is continuously changed by increasing or decreasing the rotation radius of the belt wound around the pulley. Some continuously variable transmissions include a hydraulic clutch which is disengaged by hydraulic pressure. In this continuously variable transmission, the gear ratio is changed and the hydraulic clutch is disengaged by controlling the primary pressure, the line pressure, and the clutch pressure, which are the hydraulic pressures, in various control modes by the control means.

[0004] Such a continuously variable transmission is disclosed, for example, in Japanese Patent Application Laid-Open No. 64-44347. The line pressure control method of the continuously variable transmission disclosed in this publication corrects the gear ratio during the transition from the start mode to the drive mode to the time of clutch lockup, and performs control to reduce the line pressure. I have.

[0005] Further, as a continuously variable transmission, there is one which has already been filed by the applicant of the present invention (Heisei 4).
Patent Application No. 100751). As shown in FIG. 5, the shift control device for a continuously variable transmission according to the invention of this application includes a primary pressure PPR in a hold mode HLD when the vehicle is stopped.
By increasing the primary pressure PPRIMARY in the IMARY and the normal start mode NST to a predetermined pressure, the shift control during the start operation is functioned properly to secure the shift control performance and obtain a smooth start feeling. It is. The target speed ratio RATSPH in the hold mode HLD is a speed reduction ratio (hereinafter referred to as “substantially the highest speed reduction ratio”) at which the rotational speed is transmitted from the input side to the output side while being substantially decelerated and transmitted.
Approximately full low F / L (RATSPH <F /
L, RATSPH @ F / L).

[0006]

However, in the shift control device for a continuously variable transmission, which has already been filed by the applicant of the present invention, the stopped vehicle is started as shown by an arrow A in FIG. If the driver depresses the accelerator pedal to open the throttle opening THR to a large extent, there is a disadvantage that a shock occurs. This shock occurs because the response of the engine to the opening movement of the throttle opening THR is fast and it is difficult to respond only by controlling the line pressure PLINE or the hydraulic clutch.

The continuously variable transmission has a torsional vibration system as shown in FIG. In this torsional vibration system model, Expression 1 in FIG. From Expression 1, Expression 2 is obtained as the time rate of change of the engine speed NE. The rapid increase in engine speed NE
Makes you feel shocked. It is clear from Equation 2 of the torsional vibration system model that the shock does not occur if the rate of change of the engine speed NE with time is reduced.

From the equation 2 in FIG. 6, if the gear ratio RATC, ie, iB, is lower than the full low F / L, the control performance of the hydraulic clutch (corresponding to the clutch capacity TC) is ensured even if the engine torque TE suddenly increases. can do. Since the shock indicated by the arrow A in FIG. 5 occurs almost simultaneously with the start operation of the driver, as shown in FIG.
And the target speed ratio RATSPH of the hold mode HLD, which is the speed ratio RATC during the stop of the vehicle before the start operation, is set to the full low F.
/ L so as to prepare for the start operation.

On the other hand, as shown in FIG. 8, the fuel consumption in the idling operation state in the D range of the continuously variable transmission tends to increase as the speed ratio RATC becomes lower. This is because in the idling operation state in the D range, the engine load increases as the speed ratio RATC decreases. Therefore, if the speed ratio RATC is unnecessarily reduced, vibration and noise increase, and engine stall may be caused. That is, as shown in FIG. 6, in the idling operation state in the D range of the continuously variable transmission having the input side connected to the engine and the hydraulic clutch on the output side, as shown in FIG. I have. In the hold mode HLD, a clutch pressure PCLUTCH (dashed line) is supplied to the extent that the hydraulic clutch slightly contacts, and a clutch transmission torque is generated. This clutch transmission torque is applied as a load to the engine. Assuming that the engine load torque borne by the engine is Te, the clutch transmission torque of the hydraulic clutch is Tc, and the speed ratio of the continuously variable transmission is RATC, the relationship Te = Tc / RATC. As a result, when the gear ratio RATC is lowered (in FIG. 5, RATIO is set lower than full low F / L by 0).
When the value is set to a small value on the (zero) side), the engine load torque Te increases. Therefore, in the idling operation state in the D range of the continuously variable transmission, if the gear ratio RATC is reduced, the engine load torque borne by the engine increases. Since it cannot be maintained, the fuel consumption increases.

As a result, in order to eliminate the shock indicated by the arrow A in FIG. 5, as described above, the hold mode H, which is the gear ratio RATC when the vehicle is stopped before the start operation, is simply performed.
Simply lowering the target speed ratio RATSPH of the LD lower than the full low F / L has a disadvantage that various problems as described above occur.

[0011]

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned inconveniences, the present invention is to increase the width of the groove between each of the pulley portions of the driving pulley and the driven pulley so as to wind the two pulleys. A continuously variable transmission for continuously changing the gear ratio by increasing or decreasing the radius of rotation of the belt, and a starting clutch for controlling transmission of engine torque at the output side of the continuously variable transmission. In a speed change control device for a continuously variable transmission that controls a speed ratio of a transmission to a target speed ratio set based on at least a throttle opening, a vehicle equipped with the continuously variable transmission is stopped in preparation for starting. When the brake is in the braking operation state, the target gear ratio RA of the continuously variable transmission is set as the predetermined target gear ratio reflecting the operation state of the brake.
TSPB is set to RATSPB ≒ F for the maximum reduction ratio F / L.
/ L, and when the brake is in the non-braking operation state, the target speed ratio RATSPH of the continuously variable transmission is set to R with respect to the target speed ratio RATSPB.
A control unit for controlling ATSPB> RATSPH is provided.

[0012]

According to the structure of the present invention, when the vehicle is stopped in preparation for starting, when the brake is in the braking operation state as a predetermined target gear ratio reflecting the operation state of the brake, Is the target speed ratio RA of the continuously variable transmission.
TSPB is set to RATSPB ≒ F for the maximum reduction ratio F / L.
/ L, and when the brake is in the non-braking operation state, the target speed ratio RAT of the continuously variable transmission.
SPH is set to RATS with respect to the target speed ratio RATSPB.
By performing control such that PB> RATSPH, the shift control during the starting operation can be accurately functioned and the shift control performance can be ensured without causing any trouble caused by unnecessarily lowering the target gear ratio.

That is, when the brake is in the braking operation state, for example, when the brake pedal is in the depressing operation state when the vehicle is stopped in preparation for starting, the target transmission ratio RATSPB of the continuously variable transmission is set to the maximum reduction ratio. R for F / L
By performing control such that ATSPB ≒ F / L, it is possible to secure power performance at the time of starting on an uphill road, sudden start, and the like, and suppress heat generation of the hydraulic clutch.
When the vehicle is stopped in preparation for starting and the brake is in the non-braking operation state, for example, when the brake pedal is in the releasing operation state, the target gear ratio RA of the continuously variable transmission is set.
TSPH is calculated as RAT with respect to the target speed ratio RATSPB.
By controlling SPB> RATSPH,
It is possible to prevent the occurrence of a shock during the start operation.
Furthermore, it is not necessary to add or add equipment, and it can be dealt with only by improving part of the program in the control unit.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 4 show an embodiment of the present invention. 4, reference numeral 2 denotes a belt-driven continuous variable transmission, 4 denotes a driving pulley, 6 denotes a driven pulley, 8 denotes a belt, 10 denotes an input shaft, and 12 denotes an output shaft.

The drive side pulley 4 includes a drive side fixed pulley piece 14 fixed to an input shaft 10 connected to an engine (not shown), and a drive shaft mounted on the input shaft 10 so as to be movable in the axial direction and non-rotatably. And a side movable pulley piece 16. The driven pulley 6 is connected to the driving pulley 4.
Similarly, the driven pulley piece 18 is fixed to the output shaft 12, and the driven movable pulley piece 20 is attached to the output shaft 12 so as to be axially movable and non-rotatable.

The driving side and driven side movable pulley pieces 16
Drive-side and driven-side housings 22 and 24 are mounted on the housing 20, respectively, to form drive-side and driven-side pressure oil chambers 26 and 28, respectively. In the driven-side pressure oil chamber 28, a spring for urging the driven-side movable pulley part 20 in a direction to decrease the groove width between the driven-side fixed pulley part 18 and the driven-side movable pulley part 20 is provided. And the like.

The input shaft 10 is provided with an oil pump 32. The oil pump 32 supplies the generated hydraulic pressure to the driving-side and driven-side pressure oil chambers 26 and 28, respectively, and the driving-side and driven-side movable pulley portions 16 of the driving-side and driven-side pulleys 4 and 6.
20 is moved in the axial direction by hydraulic oil of the primary pressure (ratio pressure) and the line pressure to increase or decrease the groove width. As a result, the continuously variable transmission 2 includes the drive-side / driven-side pulley 4
・ Increase or decrease the radius of rotation of the belt 8 wound around 6,
The gear ratio is changed steplessly.

The continuously variable transmission 2 has a hydraulic clutch 34 at the output end of the output shaft. The hydraulic clutch 34 includes an input-side casing 36 attached to the output shaft 12, a clutch pressure oil chamber 38 provided in the casing 36, and a piston 40 pushed by hydraulic pressure acting on the clutch pressure oil chamber 38. An annular spring 42 for urging the piston 40 in the retreating direction, a first pressure plate 44 moved forward and backward by the pushing force of the piston 40 and the urging force of the annular spring 42, and a friction on the output side. It comprises a plate 46 and a second pressure plate 48 fixed to the casing 36. The friction plate 46 is attached to a final output shaft 50 fitted on the output shaft 12.

The hydraulic clutch 34 has a clutch pressure oil chamber 38.
If the hydraulic pressure acting on the piston is increased, the piston 4
When 0 is pushed, the first pressure plate 44 and the second pressure plate 48 are brought into close contact with the friction plate 46 to be in a so-called coupled state. On the other hand, when the clutch pressure acting on the clutch pressure oil chamber 38 is reduced, the piston 40 is retracted by the urging force of the annular spring 42, and the first pressure plate 44 and the second pressure plate 48 are separated from the friction plate 46, A so-called clutch disengagement state is established. In this manner, the hydraulic clutch 34 is engaged and disengaged by the clutch pressure, and interrupts transmission of the driving force output from the continuously variable transmission 2 to the final output shaft 50.

The oil pump 32 has a suction side connected to an oil pan 54 via an oil filter 52. The discharge side of the oil pump 32 is connected to the line pressure passage 5.
6 communicates with the driven side pressure oil chamber 28.

A line pressure control valve 60 having a relief valve function is connected to the line pressure passage 56 through a line pressure extraction passage 58. The line pressure control valve 60 adjusts the discharge flow relief amount with respect to the discharge flow rate of the oil pump 32 that generates the hydraulic pressure to take out the pressure oil of the line pressure PLINE, and uses the pressure oil of the line pressure PLINE as the operating pressure to discharge the oil. It is supplied in a direction to increase the escape amount.

The line pressure control valve 60 is connected to a line pressure control valve solenoid valve 64 through a line pressure control valve passage 62. The line pressure control valve solenoid valve 64 adjusts the amount of pressure oil flow released from the pressure oil of the line pressure PLINE with respect to the pressure oil flow of the control pressure taken out by the control pressure control valve 88 described later to operate the line pressure control valve. The pressure oil is taken out and the operating oil pressure for the line pressure control valve is supplied to the line pressure control valve 60 in a direction to reduce the discharge flow relief amount.

As a result, the operation of the line pressure control valve 60 is controlled by the line pressure control valve solenoid valve 64, the discharge pressure release amount relative to the discharge flow rate of the oil pump 32 is adjusted, and the line pressure PLINE is supplied to the line pressure passage 56. (Generally 5
～25〓 / 〓 ²⁾ take out the pressure oil.

A primary pressure control valve 68 is connected to the line pressure passage 56 through a primary pressure extraction passage 66. The primary pressure control valve 68 is connected to the drive-side pressure oil chamber 26 by a primary pressure passage 70. The primary pressure control valve 68 includes a primary pressure control valve passage 7.
2, the primary pressure control valve solenoid valve 74 is connected. The operation of the primary pressure control valve 68 is controlled by a primary pressure control valve solenoid valve 74 to take out the primary pressure (ratio pressure) pressure oil into the primary pressure passage 70.

A clutch pressure control valve 78 is connected to the line pressure passage 56 by a clutch pressure extracting passage 76. The clutch pressure control valve 78 is connected to the clutch pressure passage 80.
Is connected to the clutch pressure oil chamber 38 of the hydraulic clutch 34. The clutch pressure control valve 78 is connected to a clutch pressure control valve solenoid valve 84 through a clutch pressure control valve passage 82. The operation of the clutch pressure control valve 78 is controlled by the clutch pressure control valve solenoid valve 84, and the pressure oil of the clutch pressure PCLU is taken out to the clutch pressure passage 80.

A control pressure control valve 88 is connected to the line pressure passage 56 by a control pressure extraction passage 86.
Has been contacted. This control pressure control valve 88 is
The control pressure passage 90 is connected to the solenoid valve 64 for the line pressure control valve, the solenoid valve 74 for the primary pressure control valve, and the solenoid valve 84 for the clutch pressure control valve. The control pressure control valve 88 changes the line pressure of the line pressure passage 56 (generally, 5 to 25 ° / 〓 ² ) to a constant pressure (3 to 4 ° / 〓).
² ) Take out the control oil pressure and supply it to the solenoid valves 64, 74 and 84.

A pressure sensor 94 is connected through a pressure detection passage 92 in the middle of the clutch pressure passage 80 through which the pressure oil of the clutch pressure PCLU taken out by the clutch pressure control valve 78 flows. The pressure sensor 94 is provided for controlling the hold mode HLD and the start mode NST of the continuously variable transmission 2.
In such cases, the hydraulic pressure can be directly detected when controlling the clutch pressure PCLU, which contributes to instructing the detected hydraulic pressure to be the target clutch pressure PCLUSP. In the drive mode DRV, the clutch pressure PCLU
Becomes equal to the line pressure PLINE, which can also contribute to the line pressure control.

The driving housing 2 of the driving pulley 4
2, an input shaft-side rotation speed detection gear 96 is provided, and the input shaft 1 is located near an outer peripheral portion of the input shaft-side rotation speed detection gear 96.
A zero input shaft side rotation speed detector 98 is provided. An output shaft side rotation speed detection gear 100 is provided outside the driven side housing 24 of the driven side pulley 6, and an output shaft side rotation speed detection of the output shaft 12 is provided near an outer peripheral portion of the output shaft side rotation speed detection gear 100. A vessel 102 is provided. The engine speed NE and the gear ratio (belt ratio) can be grasped from the respective rotational speeds detected by the input shaft side / output shaft side rotational speed detectors 98 and 102.

An output gear 104 composed of a forward output gear 104F and a reverse output gear 104R is provided on the final output shaft 50 on which the friction plate 46 of the hydraulic clutch 34 is mounted. The forward switching gear and the reverse switching gear are meshed with each other. Reverse output gear 104R constituting output gear 104
A final output shaft-side rotation speed detector 106 for detecting the rotation speed on the final output shaft 50 side, which is the clutch output-side rotation speed, is provided in the vicinity of the outer peripheral portion.

The final output shaft side rotational speed detector 106 is a final output shaft 5 which is connected to the drive wheels via a forward / reverse switching mechanism, an intermediate shaft, a final reduction gear, a differential mechanism, and a drive axle (not shown).
This is for detecting the clutch output side rotation speed which is the rotation speed of 0, and is capable of detecting the vehicle speed. Further, the output shaft side rotation speed detector 102 and the final output shaft side rotation speed detector 1
06, it is possible to detect the clutch input side rotation speed and the clutch output side rotation speed of the input side and the output side before and after the hydraulic clutch 34, respectively, which contributes to the detection of the clutch slip amount.

The solenoid valve 64 for the line pressure control valve, the solenoid valve 74 for the primary pressure control valve, and the solenoid valve 84 for the clutch pressure control valve are connected to a control unit 108 as control means for controlling the continuously variable transmission 2. Have been. The control unit 108 is connected to the pressure sensor 94, the input shaft-side / output shaft-side rotation speed detectors 98 and 102, and the final output shaft-side rotation speed detector 106. The control unit 108 includes a throttle opening signal, a DDTSW (driver demand switch) signal, an accelerator pedal signal, a brake switch signal, a power mode option, in addition to various signals from the pressure sensor 94 and the rotation speed detectors 98, 102, and 106. Various signals such as a signal and a shift lever position signal are input, and the continuously variable transmission 2 is controlled.

The control unit 108 of the transmission control device for controlling the transmission of the continuously variable transmission 2 controls the line pressure so as to control the gear ratio RATC and the disengagement of the hydraulic clutch 34 in various control modes according to various input signals. The operation of the control valve solenoid valve 64, the primary pressure control valve solenoid valve 74, and the clutch pressure control valve solenoid valve 84 is controlled.

The function of the input signal input to the control unit 108 will be described in detail. (1) Shift lever position signal P, R, N, D, L
Control of line pressure, ratio, and clutch required for each range by each range signal such as (2) Throttle opening signal ...... Detects engine torque from memory previously input into the program, and sets the target ratio or target engine speed (3) Idle position signal ... Improvement of accuracy in correction and control of throttle opening sensor (4) Accelerator pedal signal ... Detection of driver's will based on depression of accelerator pedal, and driving or starting (5) Brake switch signal: Detects whether the brake pedal is depressed, and determines the control direction, such as disengagement of the hydraulic clutch. (6), Power mode option signal: Sports vehicle performance Use (or economy) as an option.

The hydraulic clutch 3 by the control unit 108
There are four basic patterns for controlling the clutch pressure of No. 4. The basic pattern is as follows: (1) Neutral mode... When the shift position is N or P and the hydraulic clutch is completely disengaged, the clutch pressure is the minimum pressure (zero). (2), Hold mode. Alternatively, when the accelerator pedal is released with R and there is no driving intention, or when it is desired to decelerate during running and cut off the transmission of the engine torque, the clutch pressure is low enough to make contact with the hydraulic clutch (3), start mode (special) Start mode)
When starting the vehicle (normal start mode) or re-engaging the hydraulic clutch after disengagement from the hydraulic clutch (special start mode), the clutch pressure prevents the internal combustion engine from rising and allows the vehicle to operate smoothly. Appropriate level according to the generated torque (clutch input torque) (4), drive mode: when the vehicle shifts to the complete running state and the hydraulic clutch is completely engaged, the clutch pressure is sufficient to withstand the engine torque There are four of the higher levels.

As described above, the control unit 108 of the transmission control device
Controls the operation of the solenoid valve 64 for the line pressure control valve, the solenoid valve 74 for the primary pressure control valve, and the solenoid valve 84 for the clutch pressure control valve, and the pulley pieces 14 of the drive pulley 4 and the driven pulley 6 By increasing or decreasing the groove width between the pulleys 4 and 6 by increasing or decreasing the groove width between 16 and 18/20, the gear ratio RA of the continuously variable transmission 2 is increased or decreased.
The TC is controlled so as to attain the target gear ratio RATSP set based on at least the throttle opening, and the hydraulic clutch 34 is controlled to be disengaged.

In the shift control device for the continuously variable transmission 2 described above, the control unit 108 operates when the vehicle (not shown) equipped with the continuously variable transmission 2 is stopped in preparation for starting. As the predetermined target gear ratio RATSP reflecting the operation state of the brake (not shown), when the brake is in the braking operation state, for example, when the brake pedal is in the depressing operation state, the target gear ratio RATSPB is set to the maximum reduction ratio of full low F / SP. L is controlled so that RATSPB ≒ F / L, and when the brake is in the non-braking operation state, for example, when the brake pedal is in the releasing operation state, the target speed ratio RATSPH is set to be greater than the target speed ratio RATSPB>RATSPB> It is controlled so as to be RATSPH.

That is, if the driver does not intend to start when the vehicle is stopped, the accelerator pedal is released without being depressed, and the shift lever is moved to the neutral position N or the parking position P. , The brake pedal is depressed, and the side brake is pulled.

Therefore, when the shift lever is shifted to the reverse position R, the drive position D, or the low position L, the brake pedal is depressed, or the side brake is pulled, the driver intends to start. It can be inferred that there is no target speed ratio RATS at the time of the braking operation, which is slightly lower than the full reduction F / L of the maximum speed reduction ratio, as indicated by the target speed ratio RATSPF line indicated by the alternate long and short dash line in FIG.
Control is performed to be PB. On the other hand, when the brake pedal is released or the side brake is released, it can be inferred that there is a high possibility that the driver will start the vehicle. Therefore, the target which is slightly lower than the full-low F / L of the maximum speed reduction ratio is set. The target gear ratio RATSPH during non-braking operation is controlled to be lower than the gear ratio RATSPB.

In this embodiment, when the brake pedal is in a depressing operation state, the full reduction F / L of the maximum reduction ratio is set.
RAT so that the target gear ratio RATSP is slightly lower than
SPB (Target gear ratio RAT when brake pedal is depressed)
SP). This RATSPB is RATSPH
(RATSPB> RATSPH) is set higher than (target speed ratio RATSP in hold mode HLD).

When the brake pedal is in a depressing operation state, the target gear ratio RA is set regardless of the hold mode HLD or the normal start mode NST.
Control TSP to RATSPB (RATSP = RATSPB). Note that the target gear ratio RATSP may be controlled to RATSP = RATSPB only in the hold mode HLD. In the normal start mode NST, RATCV (THR) (target speed ratio RATSP obtained from a map of throttle opening THR and target speed ratio RATSP) is compared with RATSPB, and a higher value is set as target speed ratio RATSP. Good.

When the brake pedal is in the depressing operation state, even in the hold mode HLD,
Even in the normal start mode NST, the target speed ratio RATSP is set to RATSPB (RATSP = RATSP
By performing the control in B), it is possible to secure the power performance and prevent a problem due to the shift control.

That is, the state in which the operation of depressing the brake pedal and the operation of depressing the accelerator pedal are performed simultaneously in parallel is, for example, when the vehicle starts on an uphill road or suddenly starts.
In such a case, power performance is required rather than smooth driving feeling. That is, a high gear ratio RATC is required. Further, the calorific value of the hydraulic clutch when the stall operation is performed increases as the gear ratio RATC (reduction ratio at which the rate of rotation speed reduction from the input side to the output side is small) is lower. If the amount of heat generated by the hydraulic clutch is large, the hydraulic clutch and the transmission oil are deteriorated.

Therefore, when the brake pedal is depressed during the start operation, control is performed such that securing of required power performance and suppression of heat generation of the hydraulic clutch are prioritized over driving feeling. .

In this embodiment, when the brake pedal is in a depressing operation state when the vehicle is stopped in preparation for starting, the target speed ratio RATSPB (RATSPB ≒) is slightly lower than the full reduction F / L of the maximum reduction ratio. F / L). If the brake pedal is in the release operation state when the vehicle is stopped in preparation for starting, the target gear ratio RAT lower than the target gear ratio RATSPB is set.
Control is performed so that SPH (RATSPB> RATSPH).

As a result, the target gear ratio RAT
The shift control during the starting operation can be accurately performed and the shift control performance can be ensured without causing a problem due to lowering the SP.

As the signal of the operation state of the brake, in addition to the operation signal of the brake pedal, an operation signal of the side brake or a combined operation signal combining the operation signals of the brake pedal and the side brake may be used. it can. The RATSPB is substantially full-low F / L.
(RATSPB <F / L, RATSPB ≒ F / L), but may be full low F / L (RATSPB = F / L). Further, the RATSPH is set to a low value that does not cause a shock during the start operation.

Next, the operation will be described.

The shift control device of the continuously variable transmission 2 controls the line pressure, the primary pressure, and the clutch pressure by the control unit 108, and the pulley pieces 14, 16, and 18 of the driving pulley 4 and the driven pulley 6 respectively. The rotational speed of the belt 8 wound around the pulleys 4 and 6 is increased or decreased by increasing or decreasing the groove width between the hydraulic motors 20 and the target gear ratio RA set at least based on the throttle opening.
The control is performed so as to be TSP, and the hydraulic clutch 34
Is controlled to be dissociated.

The continuously variable transmission 2 is controlled by the control unit 108 as shown in FIG.

First, a target transmission ratio RATSP in the normal start mode NST is obtained from a map of the throttle opening THR and the target transmission ratio RATSP based on a detection signal of the throttle opening THR and a RATCV (THR) curve (200). Further, the target gear ratio RATSPH in the hold mode HLD is obtained (202), and the target gear ratio RATSPB at the time of the brake depressing operation is obtained (204).

Each of the determined target gear ratios RATSP.
RATSPH / RATSPB includes a switch SW1 (206) switched according to the control mode and a switch SW2 (20) switched according to the operation state of the brake.
According to 8), the operation is switched between the normal start mode NST and the hold mode HLD, and is switched and introduced depending on whether the brake is depressed or released.

The target gear ratio RATSP which is switched and introduced according to the control mode and the operation state of the brake is:
A filter process is performed (210), an error from the gear ratio RATC is determined (212), PI control is performed (214), and a switch S switched between the normal start mode NST or the hold mode and another control mode is performed.
W3 (216) is output as the ratio solenoid duty OPWRAT in each control mode.

The control of the continuously variable transmission 2 will be described with reference to FIG.

When the control is started (300), the shift control device of the continuously variable transmission 2 determines whether or not the normal start mode NST is set (302). If the determination (302) is YES in the normal start mode NST, the throttle opening THR and the target gear ratio R
From the map with the ATSP, the target speed ratio RA in the normal start mode NST is obtained by using a RATCV (THR) curve.
Ask for TSP.

Next, as the operation state of the brake, it is determined whether the brake switch is ON or OFF (3).
06). In this determination (306), if the brake is released and the brake switch is OFF, the target speed ratio R in the normal start mode NST is determined.
Set the ATSP speed ratio control flag RATMOD (3
08), the ratio solenoid duty OPWRAT is calculated (310), and the process returns (312).

On the other hand, in the judgment (306), the brake is depressed and the brake switch is turned on.
In the case of, the target speed ratio RATSP is set to the target speed ratio RATSPB (314) at the time of depressing the brake. This target gear ratio RATSPB is substantially full low F / L.
The gear ratio control flag RAT of this target gear ratio RATSPB
MOD is set (308), ratio solenoid duty OPWRAT is calculated (310), and return (31)
2) Do it.

In the determination (302), if the answer is NO in the normal start mode NST, it is determined whether or not the hold mode is HLD (316). In this judgment (316), in the hold mode HLD, Y
In the case of ES, the target speed ratio RATSP is set to the target speed ratio RATSPH of the hold mode HLD (318).

Next, as the operation state of the brake, it is determined whether the brake switch is ON or OFF (3).
06). In this determination (306), if the brake is released and the brake switch is OFF, the target speed ratio RATSP of the hold mode HLD is determined.
Set H speed ratio control flag RATMOD (308)
Then, the ratio solenoid duty OPWRAT is calculated (310), and the process returns (312).

On the other hand, in the judgment (306), the brake is depressed and the brake switch is turned on.
In the case of, the target gear ratio RATSP is set to the target gear ratio RATSB (314) at the time of the brake depressing operation, and the gear ratio control flag RATMOD of the target gear ratio RATSPB is set.
Is set (308), and the ratio solenoid duty O
Calculate (310) PWRAT and return (312).

If the determination (316) is NO instead of the hold mode HLD, the shift control of another control mode is performed (320), and the return (31)
2) Do it.

As described above, the shift control device of the continuously variable transmission 2 uses the control unit 8 to set the predetermined target gear ratio reflecting the operation state of the brake when the vehicle is stopped in preparation for starting. When the brake pedal is in the depressing operation state, the target speed ratio RATSPB is controlled so that RATSPB ≒ F / L with respect to the full reduction F / L of the maximum reduction ratio. The gear ratio RATSPH is changed to the target gear ratio RA.
By performing control such that RATSPB> RATSPH with respect to TSPB, the target gear ratio RATS
The shift control during the starting operation can be accurately functioned and the shift control performance can be ensured without causing a problem due to lowering P.

That is, if the brake pedal is in a depressing operation state while the vehicle is stopped in preparation for starting,
The gear ratio RATC of the continuously variable transmission 2 is set to a target gear ratio RATSPB (RA
By performing control such that TSPB ≒ F / L), it is possible to secure power performance at the time of starting on an uphill road, at the time of sudden starting, and to suppress heat generation of the hydraulic clutch 34.

When the brake pedal is in the release operation state when the vehicle is stopped in preparation for starting, the speed ratio RATC of the continuously variable transmission 2 is changed to the target speed ratio RAT.
Target speed ratio RATSPH (RATSP) lower than SPB
B> RATSPH), it is possible to prevent the occurrence of a shock at the start operation. Furthermore, it is not necessary to add or add equipment, and it can be dealt with only by improving part of the program in the control unit.

Therefore, the fuel consumption can be reduced, the fuel consumption rate can be prevented from deteriorating, the vibration and noise can be prevented from increasing, the engine stall can be prevented, and the hydraulic clutch and the transmission oil can be prevented. Degradation can be prevented. Further, since the occurrence of a shock during the start operation can be prevented, the start feeling can be improved. Furthermore, since it can be dealt with only by improving a part of the program in the control unit, the configuration is not complicated, the size is not increased, the production is easy, the cost can be maintained at low cost, and it is economically advantageous.

As described above, according to the present invention, when the vehicle is stopped in preparation for starting, the control unit controls the vehicle so that the predetermined target gear ratio reflects the operation state of the brake. The shift control performance during the starting operation can be accurately functioned and the shift control performance can be ensured without causing any trouble caused by unnecessarily lowering the target gear ratio.

That is, when the brake is in the braking operation state when the vehicle is stopped in preparation for starting, the target speed ratio RATSPB of the continuously variable transmission is set to RATSPB ≒ F with respect to the maximum reduction ratio F / L. By controlling so as to be / L, it is possible to secure the power performance at the time of starting on an uphill road or at the time of sudden starting, and to suppress the heat generation of the hydraulic clutch. Therefore, the fuel consumption can be reduced, the fuel consumption rate can be prevented from deteriorating, and the vibration and noise can be prevented from increasing,
It is possible to prevent engine stall and prevent deterioration of the hydraulic clutch and transmission oil.

When the brake is in a non-braking operation state when the vehicle is stopped in preparation for starting, the target speed ratio RATSPH of the continuously variable transmission is set to the target speed ratio RA.
By controlling the TSPB so that RATSPB> RATSPH, it is possible to prevent the occurrence of a shock during the starting operation. For this reason, the starting feeling can be improved. In addition, since it is not necessary to add or add equipment and can be dealt with only by improving a part of the program in the control unit, the structure is not complicated, the size is not increased, the production is easy, and the cost is maintained at low cost. It is economically advantageous.

[Brief description of the drawings]

FIG. 1 is a flowchart of control of a continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is a block diagram of control of a continuously variable transmission.

FIG. 3 is a time chart of control of the continuously variable transmission.

FIG. 4 is a schematic configuration diagram of a continuously variable transmission.

FIG. 5 is a time chart of control of a continuously variable transmission showing a conventional example.

FIG. 6 is a diagram showing a torsional vibration system model of the continuously variable transmission.

FIG. 7 shows a throttle opening THR and a target gear ratio RATSP.
FIG.

FIG. 8 is a diagram showing a relationship between a gear ratio RATC and fuel consumption.

[Explanation of symbols]

 2 Continuously Variable Transmission 4 Drive Pulley 6 Driven Pulley 8 Belt 32 Oil Pump 34 Hydraulic Clutch 60 Line Pressure Control Valve 68 Primary Pressure Control Valve 78 Clutch Pressure Control Valve 88 Control Pressure Control Valve 108 Control Unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-105046 (JP, A) JP-A-62-29058 (JP, A) JP-A-5-332430 (JP, A) JP-A 61-105 65949 (JP, A) JP-A-61-116160 (JP, A) JP-A-2-62463 (JP, A) JP-A-61-244955 (JP, A) JP-A-2-109748 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48 B60K 41/26

Claims (1)

(57) [Claims] 1. A continuously changing gear ratio by increasing or decreasing a groove width between pulley portions of a driving pulley and a driven pulley to increase or decrease a radius of rotation of a belt wound around the pulleys. A variable transmission and the continuously variable transmission.
A starting clutch that controls the transmission of engine torque to the output side
The pitch provided in the shift control apparatus for a continuously variable transmission is controlled to conform to the target speed ratio is set based on the gear ratio of the continuously variable transmission at least a throttle opening, equipped with the continuously variable transmission When the brake is in the braking operation state, the target transmission ratio RATSPB of the continuously variable transmission is decelerated as the predetermined target gear ratio reflecting the operation state of the brake when the vehicle to be started is stopped in preparation for starting. The ratio F / L is controlled such that RATSPB ≒ F / L, and when the brake is in the non-braking operation state, the target speed ratio RATSP of the continuously variable transmission is controlled.
H with respect to the target speed ratio RATSPB
A shift control device for a continuously variable transmission, comprising a control unit for controlling so as to satisfy> RATSPH.