JP2001214970A - Shift control device of hydraulic continuously variable transmission for vehicle - Google Patents

Abstract

(57) Abstract: A shift control device for a hydraulic continuously variable transmission for a vehicle, which can control a gear ratio while securing a hydraulic pressure even when the vehicle is running at extremely low speed or at a stop using pressure feedback control. In addition, the gear ratio can be controlled even when the hydraulic pressure for the rotating element is not sufficient or when a failure occurs in the hydraulic pressure detecting means for detecting the hydraulic pressure. SOLUTION: A pressure feedback control means 55 changes a detection value of a hydraulic pressure detection means 47 to a target hydraulic pressure setting means 55.
When feedback control is performed on the hydraulic control system of the rotary element (primary pulley) 21 so as to reach the target value set in A, and the shift is controlled, the detected value of the oil pressure detecting means is adjusted to a predetermined range by the oil pressure determining means 59A. When it is determined that the pressure is outside, the control of the hydraulic control system is switched from the pressure feedback control by the pressure feedback control means 55 to the open loop control by the open loop control means 59.

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 hydraulic continuously variable transmission for a vehicle, which controls a speed ratio by pressure feedback control or open loop control.

[0002]

2. Description of the Related Art In recent years, continuously variable transmissions have been focused on the point that they can avoid a shift shock by continuously controlling the gear ratio and that they have excellent fuel consumption efficiency. Have been. In such a continuously variable transmission, the gear ratio is generally controlled by hydraulic control.

For example, in the case of a belt-type continuously variable transmission, power generated by an engine is transmitted from a primary pulley, which is a rotating element thereof, to a secondary pulley via a belt. At this time, usually, a hydraulic pressure (line pressure) set according to basic characteristics such as transmission torque is applied to the hydraulic piston of the secondary pulley to give a clamping force to the belt, and the hydraulic piston of the primary pulley is actuated. A shift (control of a gear ratio (an effective radius ratio between the primary pulley and the secondary pulley)) is performed by adjusting the hydraulic pressure (primary pressure) to be applied.

In the case of a continuously variable transmission for a vehicle, such a shift control is generally performed by a rotation speed (rotation speed) feedback control of a primary pulley. That is, in the shift control, the target rotation speed of the primary pulley is set based on the vehicle speed and the throttle opening, and the hydraulic pressure applied to the primary pulley is controlled so that the actual rotation speed of the primary pulley becomes the target rotation speed. It is done by doing.

By the way, it is general that the rotation speed sensor becomes difficult to detect as the rotation speed becomes lower. Therefore, when the vehicle is traveling at extremely low speed or stopped, it is difficult to detect the rotation speed of the primary pulley. Therefore, the rotation speed feedback control cannot be executed, and the gear ratio is set to full low (minimum) by open loop control. (Speed ratio on the high speed side).

[0006]

However, open loop control has the following problems due to poor control accuracy. If the primary pressure is too high, the vehicle gradually shifts up when traveling on a congested road, which causes a deterioration in startability.

[0007] If the primary pressure is too low, the input torque cannot be fully transmitted at the time of restart immediately after sudden braking or the like where the speed ratio may become an intermediate speed ratio, and belt slip may occur. In addition, there is a problem that the responsiveness when the vehicle speed increases after starting and the vehicle shifts up is deteriorated. Therefore, in normal times, the target rotational speed of the rotating element is set based on the vehicle speed of the vehicle and the load of the engine mounted on the vehicle,
The rotational speed feedback control of the hydraulic control system of the primary pulley is performed so that the actual rotational speed becomes the target rotational speed. When it is detected that the vehicle is in a substantially stopped state (an extremely low speed running state or a stopped state), the rotational speed feedback control is performed. To switch the control of the hydraulic control system of the primary pulley from pressure control to pressure feedback control. In this pressure feedback control, while detecting the actual primary pressure of the hydraulic control system, the target primary pressure of the hydraulic control system is set, and the hydraulic control system of the primary pulley is fed back so that the actual primary pressure becomes the target primary pressure. Control. This makes it possible to reliably control the gear ratio to a target value (for example, full low) while securing the primary pressure when the vehicle is traveling at extremely low speed or when the vehicle is stopped.

However, in such a method, the line pressure is reduced immediately after starting, for example, at the time of switching from the rotational speed feedback control to the pressure feedback control, and thus the hydraulic cylinder of the primary pulley is filled with hydraulic oil. In such a case, if pressure feedback control is performed on the hydraulic control system of the primary pulley, control hunting occurs due to repeated overshoots and undershoots of the primary pressure, and appropriate control cannot be performed. Challenges arise.

Further, when a failure occurs in the hydraulic pressure sensor (oil pressure detecting means) for detecting the actual primary pressure, it becomes impossible to perform the pressure feedback control itself, and the primary pressure becomes insufficient and belt slip occurs. There is also a problem that such troubles occur. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and enables a gear ratio to be controlled while securing a hydraulic pressure even when a vehicle is traveling at extremely low speed or at a stop using pressure feedback control. It is an object of the present invention to provide a shift control device for a hydraulic continuously variable transmission for a vehicle, which can control the gear ratio even when the hydraulic pressure is not sufficient or when a failure occurs in a hydraulic pressure detecting means for detecting the hydraulic pressure.

[0010]

For this reason, in the shift control apparatus for a vehicle hydraulic continuously variable transmission according to the present invention, the pressure feedback control means sets the detection value of the oil pressure detection means by the target oil pressure setting means. If the hydraulic pressure determination unit determines that the detected value of the hydraulic pressure detection unit is out of the predetermined range while controlling the shift by performing feedback control of the hydraulic control system of the rotating element so as to reach the target value, The switching means switches the control of the hydraulic control system from the pressure feedback control by the pressure feedback control means to the open loop control by the open loop control means.

Therefore, by setting the above-mentioned predetermined range,
The hydraulic control system may be configured to switch from hydraulic feedback control to open-loop control when hydraulic oil is not filled in a main part (for example, a hydraulic cylinder) of the hydraulic control system of the rotating element, or may be detected by hydraulic pressure detecting means. When the value does not indicate the normal value, the hydraulic control system may be configured to be able to switch from the hydraulic feedback control to the open loop control.

Preferably, the oil pressure judging means is constituted as a failure judging means for judging a failure of the oil pressure detecting means based on a detection value of the oil pressure detecting means, and when it is judged that the oil pressure detecting means has failed, The switching means switches the control of the hydraulic control system from the pressure feedback control by the pressure feedback control means to the open loop control by the open loop control means.

[0013] The failure determining means determines that the oil pressure detecting means has failed, and the vehicle speed or the vehicle speed detected by the vehicle speed detecting means when the predetermined pressure is supplied to the hydraulic control system by the open loop control means. When the vehicle speed equivalent value becomes equal to or greater than a predetermined value, the switching unit switches the control of the hydraulic control system from the open loop control by the open loop control unit to the rotation speed feedback control by the rotation speed feedback control unit, The hydraulic control system is feedback-controlled so that the detected value becomes the target value set by the target rotation speed setting means.

In the case where the continuously variable transmission is configured as a belt-type continuously variable transmission including a primary pulley, a secondary pulley, and an endless belt wound around both pulleys, the rotary element to the primary cylinder is used as the rotating element. It is preferable to adopt a primary pulley that is hydraulically controlled by supplying hydraulic pressure, and to configure the hydraulic pressure detecting means as a hydraulic pressure sensor that detects a hydraulic pressure supplied to the primary pulley.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will now be described with reference to the drawings. FIGS. 1 to 4 show a shift control device for a hydraulic continuously variable transmission for a vehicle as an embodiment of the present invention. The description will be made based on these drawings. First,
The power transmission mechanism of the vehicle according to the present embodiment will be described. As shown in FIGS. 2A and 2B, in the power transmission mechanism, rotation output from an engine (internal combustion engine) 1 is:
The torque is transmitted to a belt-type continuously variable transmission (CVT) 20 via a torque converter (torque converter) 2 and further transmitted to a front differential 31.

A forward / reverse switching mechanism 4 is disposed between the output shaft 7 of the torque converter 2 and the input shaft 24 of the belt-type continuously variable transmission 20. The input rotation is input to the continuously variable transmission mechanism 20 via the forward / reverse switching mechanism 4.
The continuously variable transmission 20 is a hydraulic continuously variable transmission that performs shift control and the like by hydraulic control described later.

The stepless speed change mechanism 20 will be described in more detail. The stepless speed change mechanism 20 includes a primary pulley (rotating element of the stepless speed change mechanism 20) 21, a secondary pulley 22, and a belt 23. The rotation input to the primary shaft 24 from the inversion switching mechanism 4 is input to the secondary pulley 22 via the belt 23 from the primary pulley 21 coaxially integrated with the primary shaft 24.

The primary pulley 21 and the secondary pulley 22 are respectively two sheaves 21a, 21 which rotate integrally.
1b, 22a and 22b. One of the sheaves 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.

The hydraulic pistons 21c and 22c are supplied with a control oil pressure obtained by pressurizing hydraulic oil in an oil tank 61 by an oil pump 62, and the movable sheave 2 is responsive to the control oil pressure.
The pressing force of the fixed sheaves 21a and 22a of the first sheaves 1b and 22b is adjusted. Secondary pulley 22
The hydraulic piston 22c has a pressure regulating valve (line pressure regulating valve)
The line pressure adjusted by the pressure 63 is applied to the hydraulic piston 21 c of the primary pulley 21, and the hydraulic oil adjusted by the pressure adjusting valve 63 and then adjusted by the flow rate control valve (speed ratio adjusting valve) 64 is adjusted. is supplied, the hydraulic fluid is adapted to act as a hydraulic adjustment speed ratio (primary pressure) P _P. The pressure regulating valve 63 is controlled by duty-controlling a line pressure control solenoid 63A by an electric signal. The flow control valve 64 is controlled by performing duty control on a shift control solenoid 64A with an electric signal, and is also referred to as a shift solenoid valve.

The line pressure should be as low as possible within a range in which power transmission can be ensured while avoiding slippage of the belt 23, so as to reduce the energy loss due to the oil pump 62 and the durability of the transmission itself. Is important in raising
The belt tension control pressure (pressure corresponding to the line pressure) P _out is set based on the transmission torque and the value corresponding to the belt hanging radius of the secondary pulley 22, and based on the belt tension control pressure P _out , the pressure regulating valve 63 is set. Is controlled to adjust the discharge pressure of the oil pump 62, thereby performing line pressure control.

Further, the primary pressure P _P applied to the hydraulic piston 21c of the line pressure applied to the hydraulic piston 22c P _L and the primary pulley 21 of the secondary pulley 22, the command signal of the controller (electronic control control unit = ECU) 50 , Respectively. That is, the ECU 50 includes an engine rotation speed sensor (a crank angle sensor or a cam angle sensor).
41, throttle opening sensor 46, primary pulley 2
A primary rotation sensor (rotation speed detection means) 43 for detecting the rotation speed (rotation speed) 1, a secondary rotation sensor (vehicle speed detection means) 44 for detecting the rotation speed (rotation speed) of the secondary pulley 22, and a line pressure detection line pressure sensor 45, the speed ratio adjusting hydraulic being adapted each detection signal, such as a primary pressure sensor 47 for detecting the (primary pressure) P _P is input, the ECU 50, each on the basis of these detection signals pulley A pressure regulating valve 63 and a flow rate control valve 64 provided in a hydraulic pressure supply system to 21 and 22 are controlled.

Then, as shown in FIG.
Reference numeral 50 denotes control of the above-described flow control valve 64 (speed ratio control).
(Shift control means or primary pressure control means) 52 and a function (line pressure control means) 53 for controlling the pressure regulating valve 63 (line pressure control).
In particular, as shown in FIG. 1, the speed change control means 52 includes, as shown in FIG. 54, a pressure feedback control means 55 for performing pressure feedback control on the flow control valve 64, an open loop control means 59 for performing open loop control on the flow control valve 64, and a detection value (actual primary pressure) of the primary pressure sensor 47 within a predetermined range. Primary pressure determination means (oil pressure determination means) 59A
And switching means 56 for switching between the rotation number feedback control, the pressure feedback control and the open loop control.

Among them, the rotational speed feedback control means 54 provides a parameter [here, a parameter corresponding to the vehicle speed of the vehicle.
Target primary rotation setting means for setting a target rotation speed of the primary pulley 21 from the rotation speed of the secondary pulley 22 corresponding to the vehicle speed (secondary rotation speed)] and the load of the engine mounted on the vehicle (here, the accelerator opening). (Target rotation speed setting) 54A and primary rotation sensor 43
And the actual rotation speed N _P and the deviation between the target rotational speed _{N PT ΔN P (= N PT} -N P) calculating a (subtractor) 54B of the primary pulley 21 detected in, PID on the deviation .DELTA.N _P
Correction based on [proportional correction (P correction), integral correction (I correction), differential correction (D Correction)] and the PID correction unit 54C for performing control variable subjected to PID correction on the deviation .DELTA.N _P (shift duty) And the actual rotational speed N of the primary pulley 21
_The flow rate control valve (speed ratio adjusting valve) 64 is feedback-controlled so that _P becomes the target rotation speed _NPT .

The pressure feedback control means 55
Is a target primary pressure setting means (target oil pressure setting means) for setting a target value (target primary pressure) P _PT of primary pressure from an input torque input to the belt-type continuously variable transmission 20.
Calculating 55A and a primary pressure detected by the primary pressure sensor 47 deviation [Delta] P _P between P _P and the target primary pressure P _PT (working oil pressure supplied to the hydraulic piston 21c of the primary pulley _{21) (= P PT -P P} ) a calculation means (subtractor) 55B which, PID correction on the deviation [Delta] P _P and PID correction unit 55C for performing [proportional correction (P correction), integral correction (I correction), differential correction (D correction)], the deviation [Delta] P _P
The control amount that has been subjected to PID correction based on the (shift duty), the actual primary pressure P _P is the flow rate control valve so that the target primary pressure P _PT (gear ratio control valve) 64 for feedback control of the.

It should be noted that the input torque Tin to the primary pulley 21 is equal to the output torque Te during steady rotation of the engine,
It can be calculated from the increased output torque ΔTe and the torque ratio t of the torque converter 2 based on the following equation. Tin = (Te + ΔTe) × t In the above equation, the sum (Te + ΔTe) of the output torque Te during steady rotation and the engine torque increase ΔTe corresponds to the output torque of the engine 1, and this engine output torque (Te + ΔTe) is expressed as The torque ratio t is multiplied so as to be input to the primary pulley 21 of the continuously variable transmission mechanism 20 according to the torque ratio t of the torque converter 2.

The torque ratio t is obtained by calculating the input / output speed ratio of the torque converter 2 [the output rotation speed of the torque converter 2 (= the rotation speed Nin of the primary pulley 21 of the continuously variable transmission mechanism 20) to the input rotation speed of the torque converter 2 (= the speed of the engine 1). (Nin / Ne) divided by the rotational speed Ne)].
Further, the output torque Te during steady rotation of the engine can be estimated from the engine rotation speed Ne detected by the engine rotation speed sensor 41 and the throttle opening θ detected by the throttle opening sensor 46. Output torque Te with respect to engine rotation speed Ne and throttle opening θ
Is used to determine the output torque Te. The output torque Te may be obtained from the engine rotation speed Ne and the intake charging efficiency A / Ne, or may be obtained from the engine rotation speed Ne and the average effective pressure (torque / displacement amount; target Pe). Alternatively, it may be obtained from the engine rotation speed Ne and the boost pressure.

The increased output torque ΔTe is an engine torque that increases when the fuel supply amount to the engine is increased more than usual, such as during warm-up or acceleration of the engine. Since the increase in the fuel supply amount at this time corresponds to the decrease in the air-fuel ratio of the air-fuel mixture, here, based on the air-fuel ratio detection information of the A / F sensor 47 provided in the exhaust passage,
The engine torque increase ΔTe is determined.
If the A / F sensor 47 is not provided, the engine torque increase ΔTe may be obtained based on information on the target air-fuel ratio for engine air-fuel ratio control.

Then, the open loop control means 59
When a predetermined condition is satisfied at the time of pressure feedback control by the pressure feedback control means 55, the flow control valve 64 is subjected to open loop control with a predetermined press-fit duty set in advance. The predetermined compression duty is defined as a hydraulic cylinder (not shown) of the primary pulley 21.
To a value as close as possible to the average value of the duty at the time of pressure feedback control, and is set in advance from test results and the like. The above-mentioned predetermined condition will be described later.

In the switching means 56, the flow rate control valve 64 is normally controlled by the rotation speed feedback control by the rotation speed feedback control means 54, and the vehicle is substantially in a stopped state (an extremely low speed running state or a stopped state). If detected, the control of the flow rate control valve (hydraulic control system) 64 is switched from the rotational speed feedback control to the pressure feedback control by the pressure feedback control means 55.

[0030] In the present embodiment, the vehicle is whether in a substantially stopped state, indirectly corresponding directly to the rotation speed (the secondary rotational speed) N _S and the vehicle speed of the corresponding secondary pulley 22 on the vehicle speed The determination is made based on the rotation speed (primary rotation speed) N _P of the primary pulley 21. That is, while the vehicle is traveling, when the secondary rotation speed N _S is preset small threshold N into the _S1 less than or primary speed N _P reaches a preset small threshold value N _P1 or less, vehicle Is determined to be substantially stopped. Conversely, when the vehicle is in a substantially stopped state, the secondary rotation speed N _S1 becomes equal to or more than a predetermined small threshold value N _S2 (> N _S1 ) and the primary rotation speed N _P becomes a predetermined small threshold value N S. When it becomes _P2 (> N _P1 ) or more, it is determined that the vehicle has returned to the running state.

As described above, it is determined whether or not the vehicle has substantially stopped and whether or not the vehicle has returned to the running state using both the secondary rotation speed N _S and the primary rotation speed N _P. For reasons. That is, when the primary rotation speed cannot be accurately detected, the primary rotation speed cannot be naturally feedback-controlled, and when the secondary rotation speed cannot be accurately detected,
This is because the primary rotation speed cannot be set as a target, and thus the primary rotation speed cannot be feedback-controlled.

Further, based on the information of the two rotation speed sensors, the primary rotation sensor 43 and the secondary rotation sensor 44, when the detected values of both the sensors 43, 44 become equal to or more than the respective threshold values N _S2 , N _P2 , the vehicle is _stopped. By determining that the vehicle has returned to the running state, it is possible to quickly and reliably determine that the vehicle has returned to the running state.
The reason why hysteresis is provided for the determination thresholds N _S1 and N _S2 and N _P1 and N _P2 is to prevent hunting of control and realize stable control.

[0033] Subsequently explained is the primary pressure determining means 59A, the primary pressure determining means 59A is a hydraulic range or not in when the actual primary pressure P _P is the hydraulic oil is filled in the hydraulic cylinder of primary pulley 21 Is a means for determining whether In the primary pressure determination means 59A,
Actual primary pressure _PP and primary pressure sensor 4 shown in FIG.
The above determination is made based on the relationship with the sensor output value (detection value) VP of _No. 7.

Specifically, the primary pressure judging means 59A
, At the time of pressure feedback control, whether the sensor output value of the primary pressure sensor 47 (detected value) V _P is greater than the predetermined output value V _P1 that is set in advance, i.e., the actual primary pressure P _P is It is determined whether or not the value is larger than a predetermined value P _P1 set in advance. Further, at the time of the open loop control, whether the sensor output value V _P is preset predetermined output value V _P2 (> V _P1) above, i.e., the actual primary pressure P _P is a predetermined value P _P2
(> P _P1 ) or not. And
The primary pressure determination means 59A is based on the above determination,
The actual primary pressure P _P at the time of pressure feedback control
There and when it becomes less than the predetermined value P _P1, when the actual primary pressure P _P at the time of the open loop control is equal to or greater than the predetermined value P _P2, and outputs a switching instruction signal to the switching means 56.

Further, the primary pressure judging means 59A
It has a failure determination means 59B as its functional element.
Failure determining means 59B is a means for determining a failure of the primary pressure sensor 47 based on the sensor output value V _P of the primary pressure sensor 47. That is, the primary pressure sensor 47
If There was or short broken, because the sensor output value V _P indicates an abnormal value not be the normal, a decision is made as to whether the sensor output value V _P is within a predetermined normal range This makes it possible to determine whether the primary pressure sensor 47 has failed.

Specifically, the failure determination means 59B performs the primary pressure sensor 4 control during the pressure feedback control.
The output value V _P 7 is determined whether the range of from a preset predetermined output value V _min to the predetermined output value _{V max (V max> V min} ). Incidentally, (equivalent value when the primary pressure P _P is 0) or a lower limit output value V _Pmi lower output value V _Pmin when the output value V _P is normal of said predetermined output value V _min is the primary pressure sensor 47 It is a value less than or equal to _n . The predetermined output value of the V _max is the upper limit output value V _Pmax (primary pressure P _P in the case where the output value V _P is normal for primary pressure sensor 47
Is the maximum value P _Pmax ) or a value equal to or more than the upper limit output value V _Pmax .

The failure determining means 59B, when that the output value V _P of the primary pressure sensor 47 is below a predetermined output value V _{m in} is determined continuously for a predetermined time or at a predetermined output value V _{ma x} more If it is determined that there is an error for a predetermined time, it is determined that the primary pressure sensor 47 has failed. Then, the primary pressure determining means 59A, the lower limit output value V _Pmin output value V _P of the primary pressure sensor 47
, That is, instruct the actual primary pressure _PP to be regarded as zero. In response to the instruction from the failure determination means 59B, the primary pressure sensor 47 outputs the switching instruction signal to the switching means 56 assuming that the actual primary pressure _PP is 0.

When the precondition for pressure feedback control is satisfied (when the vehicle is substantially stopped), the switching means 56
A function 56A for switching between pressure feedback control and open loop control based on the switching instruction signal from the primary pressure determination means 59A is provided. That is, in the switching means 56, when pressure feedback control (when the vehicle is in a substantially stopped state), the actual primary pressure P _P is determined to be equal to or less than the predetermined value P _P1, switching instruction signal from the primary pressure determining means 59A Is input, the control of the flow rate control valve (speed ratio adjusting valve) 64 is switched from the pressure feedback control by the pressure feedback control means 55 to the open loop control by the open loop control means 59.

When the open loop control is performed when the precondition for the pressure feedback control is satisfied (when the vehicle is substantially stopped), the actual primary pressure _PP becomes equal to a predetermined value _PP2.
The primary pressure determination means 59
When the switching instruction signal is input from A, the control of the flow rate control valve (gear ratio adjusting valve) 64 is switched from the open loop control by the open loop control means 59 to the pressure feedback control by the pressure feedback control means 55. ing.

The determination thresholds P _P1 and P _P2 for switching between the pressure feedback control and the open loop control are values that can be estimated that the hydraulic cylinder (not shown) of the primary pulley 21 is not filled with hydraulic oil. . These determination thresholds are also set in advance from test results and the like. Also, the reason why the hysteresis is provided by the two values of P _P1 and P _P2 is to prevent control hunting and realize stable control as described above.

In the present embodiment, the gear ratio is controlled to full / low while appropriately securing the primary pressure during the pressure feedback control. In other words, when controlling the gear ratio to full low, the primary pressure is made lower than the line pressure. At this time, the primary pressure is appropriately reduced while recognizing the actual primary pressure. Of course, the switching means 56 returns the control mode of the flow control valve 64 from pressure feedback control or open loop control to rotation speed feedback control when the vehicle changes from a substantially stopped state to a running state.

The flow rate control valve 64 is controlled by controlling the duty of the speed change control solenoid 64A. The control duty of the speed change control solenoid 64A is calculated by a calculation means (adder) 58 by a rotational speed feedback control means. The deviation ΔN _P calculated by
D-corrected control amount (shift duty) or deviation Δ calculated by pressure feedback control means 55
Control variable subjected to PID correction P _P (shift duty)
Is added to the shift reference duty calculated by the shift reference duty calculator 57 from the oil temperature, the line pressure, the gear ratio, and the input rotation speed. The oil temperature,
The line pressure and the input rotation speed can be obtained from, for example, the detection results of the oil pressure sensor, the line pressure sensor 45, and the engine rotation speed sensor 41, and the gear ratio can be obtained, for example, by the primary rotation speed and the secondary rotation speed detected by the primary rotation sensor 43. It can be calculated from the primary rotation speed detected by the rotation sensor 44.

Since the shift control device for a vehicle hydraulic continuously variable transmission according to one embodiment of the present invention is configured as described above, shift control is performed, for example, as shown in the flowchart of FIG. . That is, first, step S1
0, the shift reference duty calculating means 57 calculates the oil temperature,
A shift reference duty is calculated from the line pressure, the speed ratio, and the input rotation speed. Next, in step S20, it is determined whether the flag F1 is 1. The flag F1 is set to 1 when it is determined that the vehicle is in a running state, and is set to 0 when it is determined that the vehicle is in a substantially stopped state.

Here, for example, in the previous control cycle, the vehicle
If it is determined that the vehicle is in the traveling state, step S30, step
Proceeding to step S40, in step S30 secondary rotation
Number N _SIs a preset threshold N_S1Greater than or threshold
N_S1It is determined whether the following conditions are satisfied.
Mali speed N_PIs a preset threshold N_P1Greater than
Ruka threshold N_P1It is determined whether or not:

In step S30, it is determined that the secondary rotation speed N _S is larger than the threshold value N _S1 , and
If it is determined at 40 that the primary rotation speed N _P is greater than the threshold value N _P1 , the vehicle is in the running state,
The rotation speed feedback control means 54 controls the flow control valve 6 so that the rotation speed of the primary pulley 21 becomes a target value.
4 is controlled.

That is, the process proceeds to step S50, where the target
Imari rotation setting means 54A corresponds to the vehicle speed of the vehicle
Parameters (here, secondary rotation speed) and vehicle
Load of the mounted engine (here, accelerator opening)
Then, the target rotation speed of the primary pulley 21 is set.
Then, the process proceeds to step S60, where the calculation unit 54B
And the actual rotational speed N of the primary pulley 21_PAnd target speed
N_PTDeviation ΔN from_P(= N _PT-N_P) Is calculated and the PID supplement is calculated.
The deviation ΔN is determined by the corrector 54C._PPID correction
You.

Further, at step S70, the flag F1 is set to 1
Held in, the process proceeds to step S80, on the basis of the shift reference duty calculated in step S10, the transmission duty obtained in step S60 (control amount that has been subjected to PID correction deviation .DELTA.N _P), the shift control solenoid 64A Are driven by duty control. On the other hand, when it is determined in step S30 that the secondary rotation speed N _S is equal to or less than the threshold value N _S1 , or in step S40, the primary rotation speed N _P
Is determined to be equal to or less than the threshold value _NP1 , the vehicle is assumed to be in a substantially stopped state, and the pressure feedback control means 55 controls the flow control valve 64 so that the hydraulic pressure acting on the primary pulley 21 becomes the target value. Control.

That is, the routine proceeds to step S110, where the target primary pressure setting means 55A sets a target primary pressure (target primary pressure) P _PT from the input torque input to the belt-type continuously variable transmission 20. Then, the process proceeds to step S111 to determine whether or not the flag F3 is 1.
This flag F3 indicates that the primary pressure sensor 47 is normal (that is, the sensor output value V of the primary pressure sensor 47).
_P is a) 1 when it is in the range of from V _min to V _max, if the primary pressure sensor 47 has failed (i.e., the sensor output value V _P of the primary pressure sensor 47 V _min or more or less or V _max Sometimes) 0. Also, the flag F3
Is set to 1.

If the flag F3 is 1, step S11
The process proceeds to 2, and it is determined whether the flag F2 is 1. The flag F2 is 1 when the actual primary pressure P _P is capable of executing the pressure feedback control is ensured by a predetermined level
Is a real primary pressure P _P is 0 if it can not ensure the controllability in the pressure feedback control not secured by a predetermined level. The initial value of the flag F2 is 1
It is said.

If the flag F2 is 1, step S11
Advances to 3, by the determination of the failure determining means 59B, it is determined whether the sensor output value V _P of the primary pressure sensor 47 is within the range of from V _min to V _max, where the sensor output value V _P
If There range from V _min to V _max, step S11
Proceed to 4. In step S114, it is determined in primary pressure determining means 59A, the actual primary pressure P _P is determined whether large or predetermined value P _P1 less than the predetermined value P _P1, where the actual primary pressure P _P is a predetermined value If it is greater than P _P1 ,
The process proceeds to step S120, the calculating means 55B, the deviation ΔP between the actual primary pressure P _P and the target primary pressure P _PT
P (= P _PT -P _P ) is calculated, and PID correction is performed on this deviation ΔP _P by PID correction means 55C.

Further, the flag F2 is set at step S122.
The flag F1 is set to 0 in step S130.
To step S80, and calculate in step S10.
The calculated shift reference duty and obtained in step S120
Shift duty (deviation ΔP _PPID corrected
Flow rate control valve (shift solenoid valve)
(Lube) 64 speed control solenoid 64A pressure feed
It is driven by duty control using back control.

On the other hand, in step S113,
Sensor output value V of the Mari pressure sensor 47 _PIs V_minLess than or V
_maxIf it is determined that the above has continued for a predetermined time,
In step S115, the flag F3 is set to 0, and step S115
Proceeding to 124, the predetermined press-fit
And the Then, in step S130, the flag F1 is set.
Is set to 0, the process proceeds to step S80,
The shift reference duty calculated in step 10 and step S12
Based on the shift duty (predetermined press-fit value) obtained in 4
To control the shift control solenoid 64A for open loop control.
It is driven by the duty control used.

In step S111, the flag F
When 3 is 0, the process proceeds to step S124 to perform the same processing as described above, and further performs the processing of step S130 and step S80. If the actual primary pressure P _P is equal to or less than the predetermined value P _P1 in step S114,
At step 117, the flag F2 is set to 0, and step S124 is performed.
Then, the predetermined press-fitting predetermined value is set as the shift duty. Further, in step S130, the flag F1 is set to 0, and the process proceeds to step S80, where the shift control solenoid is operated based on the shift reference duty calculated in step S10 and the shift duty (predetermined press-fit value) determined in step S124. 64A is driven by duty control using open loop control.

In step S112, the flag F
If 2 is 0, the process proceeds to step S116, where the actual primary pressure P _P is determined by the actual primary pressure determination means 59A.
Is greater than or equal to a predetermined value P _P2 or less than a predetermined value P _P2 . Here, if the actual primary pressure P _P is equal to or more than the predetermined value P _P2 , the process proceeds to step S120, and similarly to step S120,
Step S122, step S130, step S80
Is performed. On the other hand, the actual primary pressure _PP is equal to the predetermined value P.
If less than _P2, the process proceeds to step S124, where the same processing as described above is performed.
Step 80 is performed.

Then, when the flag F1 is set to 0 assuming that the vehicle is substantially stopped, the process proceeds from step S20 to step S90 and step S100.
In step S90 the secondary rotation speed N _S is equal to or a predetermined threshold value N _S2 or steps S1
In the case of 00, the primary rotation speed N _P is set to a predetermined threshold N
It is determined whether it is _P2 or more.

If it is determined in step S90 that the secondary rotation speed N _S is less than the threshold value N _S2 , or if it is determined in step S100 that the primary rotation speed N _P is less than the threshold value N _P2 , the vehicle Holds the substantially stopped state, so that the flag F3 is 1 or 0 (step S111) and the flag F2 is 1 or 0 (step S11), as described above.
2), the sensor output value V _P of the primary pressure sensor 47 is V
whether the range from _min to V _max (step S11
3), the actual primary pressure P _P Do large or not than a predetermined value P _P1 (step S114), the actual primary pressure P _P is a predetermined value P
Pressure feedback control (steps S120, S8) is performed according to the determination result of whether or not _P2 or more (step S116).
0) or open loop control (steps S124, S8)
0), the shift control solenoid 64A is duty-controlled.

Meanwhile, the secondary rotational speed N _S is determined that more than the threshold value N _S2 in step S90, and step S
If it is determined in step 100 that the primary rotation speed N _P is equal to or greater than the threshold value N _P2 , the vehicle has returned to the running state, and the rotation is switched to rotation speed feedback in steps S50, S60, and S80. Step S7
At 0, the flag F1 is set to 1.

As described above, when the vehicle is traveling normally without being in a substantially stopped state (an extremely low speed traveling state or a stopped state), the switching means 56 selects the rotational speed feedback control by the rotational speed feedback control means 54 and the flow control valve 64. The speed change ratio is controlled by duty control of the speed change control solenoid 64A using the speed feedback to control the speed ratio of the primary pulley so that the speed ratio is optimized by the speed feedback control.

On the other hand, when the vehicle is in a substantially stopped state (an extremely low speed running state or a stopped state), the hydraulic control by the switching means 56 is changed from the rotation number feedback control by the rotation number feedback control means 54 to the pressure feedback control means 55. is switched to the pressure feedback control, the shift control solenoid 64A of the flow control valve 64 is duty-controlled by the pressure feedback control, since controlling the adjusted transmission ratio the primary pressure P _P, a vehicle is substantially stopped state primary Even when it is difficult to detect the rotation speed of the pulley 21, such as the actual rotation speed N _P, it is possible to control the gear ratio to full low while maintaining the primary pressure at an appropriate value (target primary pressure) by pressure feedback control. Can be. Therefore, for example, the primary pressure does not become excessively high, and it is possible to avoid a situation in which the speed ratio gradually shifts to the overdrive side when traveling on a congested road, so that good startability can be maintained. In addition, the belt pressure at the time of restarting can be reliably avoided without the primary pressure becoming excessively low.

Further, even when the vehicle is substantially stopped, when the actual primary pressure P _P becomes equal to or less than the predetermined value P _P1 and thereafter becomes less than the predetermined value P _P2 , that is, the hydraulic oil of the primary pulley 21 is supplied to the hydraulic cylinder. Is not satisfied, the control of the hydraulic control system is switched from the pressure feedback control by the pressure feedback control means 55 to the open loop control by the open loop control means 59.
It is possible to prevent overshooting and undershooting of the primary pressure and control hunting due to repetition of these, and to appropriately control the hydraulic control system of the primary pulley. Therefore, there is an advantage that the control performance of the speed ratio can be ensured.

Further, when the sensor output value V _P of the primary pressure sensor 47 is equal to or less than V _min or equal to or more than V _max , that is, when the primary pressure sensor 47 has failed, the actual primary pressure P _P is zero. And the pressure feedback control by the pressure feedback control means 55,
Since the control of the hydraulic control system is switched to the open loop control by the open loop control means 59, belt slip due to at least a shortage of the primary pressure can be prevented, and there is an advantage that the worst case of running disability can be avoided. .

Even if the primary pressure sensor 47 is out of order, the control of the hydraulic control system of the primary pulley is switched from open loop control to rotational feedback control when the vehicle shifts from a substantially stopped state to a running state. After that, there is also an advantage that the control performance of the gear ratio can be ensured and the traveling is not hindered. It should be noted that the present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the spirit of the present invention.

For example, in this embodiment, when the vehicle is substantially stopped, the gear ratio is controlled to be full low, but the control of the gear ratio is not limited to full low. That is, it is conceivable to control the state to an intermediate speed ratio expected from the relationship between the line pressure and the primary pressure. Further, the vehicle is determined whether in a substantially stopped or running, the only one of the secondary rotation speed N _S and primary speed N _P, or may be based on other parameters related to the vehicle speed.

Further, the hydraulic control systems 63 and 64 are not limited to duty solenoid control, and other controls such as position control using a linear solenoid can be applied. Further, a warning lamp may be provided in the vehicle cabin, and when the failure determining means 59B determines that the primary pressure sensor 47 has failed, the warning lamp may be turned on. As a result, the vehicle can be promptly brought to a maintenance shop or the like, and the failed primary pressure sensor 47 can be repaired and replaced.

Further, according to the present invention, if the hydraulic pressure is too low when performing the hydraulic feedback control, the control is switched to the open loop control which can secure the hydraulic pressure by a predetermined press-fitting control. The speed ratio can be controlled while preventing the occurrence of control hunting due to the repetition of. Therefore, the present invention is not limited to the one that performs the hydraulic feedback control only when the vehicle is substantially stopped, as in the present embodiment, but can be widely applied to the one that controls the hydraulic control system by the hydraulic feedback control. It is.

Further, the present invention is not limited to the belt type, but can be widely applied to a hydraulic type continuously variable transmission, for example, to a toroidal type.

[0067]

As described above in detail, according to the shift control device for a hydraulic continuously variable transmission for a vehicle of the present invention, the main part (for example, the hydraulic cylinder) of the hydraulic control system of the rotating element is filled with the hydraulic oil. If not, the control by the hydraulic control system can be switched from the hydraulic feedback control to the open loop control, and so-called control hunting, in which the hydraulic pressure repeats overshoot and undershoot, can be prevented. Therefore, the hydraulic cylinder of the rotary element is not filled with hydraulic oil due to a decrease in the basic pressure of the hydraulic system (such as line pressure) immediately after the start or at the time of switching from the rotational speed feedback control to the pressure feedback control. Also in the case, the hydraulic control performance of the rotating element, that is,
There is an advantage that the control performance of the speed ratio can be secured.

Further, depending on the setting of the predetermined range, the hydraulic control system may be configured to switch from the hydraulic feedback control to the open loop control when the detected value of the hydraulic pressure detecting means does not indicate a normal value. There is an advantage that troubles due to insufficient hydraulic pressure can be prevented. In addition, it is possible to positively determine the failure of the hydraulic pressure detecting means and switch the hydraulic control system from the hydraulic feedback control to the open loop control when the hydraulic pressure detecting means fails, thereby preventing a problem due to insufficient hydraulic pressure. There is also (claim 2).

Further, even if the hydraulic pressure detecting means is out of order, the control of the hydraulic control system of the rotating elements is switched from the open loop control to the rotational feedback control when the vehicle speed or the vehicle speed equivalent value exceeds a predetermined value. After that, there is also an advantage that the control performance of the gear ratio can be ensured and the traveling is not hindered (claim 3).

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of a shift control device of a hydraulic continuously variable transmission for a vehicle as one embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a power transmission system of a vehicle with a hydraulic continuously variable transmission according to one embodiment of the present invention;
(A) is a schematic configuration diagram of a power transmission system including the continuously variable transmission, and (b) is a configuration diagram of the continuously variable transmission.

FIG. 3 is a graph showing a relationship between a primary pressure and a sensor output value of a primary pressure sensor according to one embodiment of the present invention.

FIG. 4 is a flowchart showing the control contents of a shift control device for a vehicle hydraulic continuously variable transmission as one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 20 Hydraulic continuously variable transmission 21 Primary pulley (rotating element) 43 Primary rotation sensor (rotation speed detection means) 44 Secondary rotation sensor (vehicle speed detection means) 47 Primary pressure sensor (oil pressure detection means) 52 Shift control means 53 Line Pressure control means 54 rotation number feedback control means 54A target primary rotation setting means 55 pressure feedback control means 55A target primary pressure setting means (target oil pressure setting means) 56 switching means 59 open loop control means 59A primary pressure judgment means (oil pressure judgment means) 59B Failure determination means 63 Pressure regulating valve (line pressure regulating valve) 64 Flow control valve (hydraulic control system, gear ratio regulating valve)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16H 59:44 F16H 59:44 (72) Inventor Minoru Seiichi Minoru, Tokyo F term in Mitsubishi Motors Corporation (reference)

Claims (3)

[Claims] 1. A shift control device for a hydraulic hydraulic continuously variable transmission for controlling a gear ratio by controlling a hydraulic control system of a rotating element, wherein a hydraulic pressure detecting means for detecting a hydraulic pressure supplied to the hydraulic control system. Target oil pressure setting means for setting a target value of the oil pressure supplied to the oil pressure control system; and the oil pressure control system so that the detected value of the oil pressure detecting means becomes the target value set by the target oil pressure setting means. Pressure feedback control means for performing feedback control of the hydraulic pressure control system, open loop control means for supplying a predetermined pressure to the hydraulic pressure control system, hydraulic pressure determination means for determining whether a detection value of the hydraulic pressure detection means is within a predetermined range, If the oil pressure determination means determines that the detected value is outside the predetermined range, the pressure feedback control by the pressure feedback control means is changed to an automatic control by the open loop control means. A shift control device for a hydraulic continuously variable transmission for a vehicle, comprising: switching means for switching control of the hydraulic control system to open loop control. 2. The apparatus according to claim 1, wherein the hydraulic pressure determining means determines a failure of the hydraulic pressure detecting means based on a detection value of the hydraulic pressure detecting means. When it is determined that a malfunction has occurred, control of the hydraulic control system is switched from pressure feedback control by the pressure feedback control means to open loop control by the open loop control means. Item 3. A shift control device for a hydraulically operated continuously variable transmission for vehicles according to Item 1. 3. A vehicle speed detecting means for detecting a vehicle speed or a vehicle speed equivalent value; a rotating speed detecting means for detecting a rotating speed of the rotating element; and a target for setting a target value of the rotating speed of the rotating element from a vehicle driving state. Rotation speed setting means; and rotation speed feedback control means for performing feedback control of the hydraulic control system so that the detection value of the rotation speed detection means becomes the target value set by the target rotation speed setting means. When the detection value of the vehicle speed detection means is equal to or more than a predetermined value, the means changes the hydraulic control system from the open loop control by the open loop control means to the rotation speed feedback control by the rotation speed feedback control means. 3. The shift control device for a hydraulic continuously variable transmission for a vehicle according to claim 2, wherein the control is switched.