JP4652475B2 - Control device and control method for belt type continuously variable transmission - Google Patents

Description

  The present invention relates to a control device and a control method for a belt-type continuously variable transmission that performs belt slip control for slipping a belt stretched around a pulley at a predetermined slip rate.

  Conventionally, as a control device for a belt-type continuously variable transmission, an actual secondary hydraulic pressure is decreased from that during normal control, and belt slip control is performed to slip a belt stretched around a pulley at a predetermined slip ratio. The actual secondary oil pressure is controlled based on a multiplier between the vibration component included in the secondary oil pressure and the vibration component included in the actual gear ratio. As a result, there is no need to directly detect the belt slip ratio, and it is known that belt slip control can be easily performed. In addition, superimposition of a predetermined sine wave on the command secondary oil pressure, that is, the command secondary oil pressure is vibrated, and the actual secondary oil pressure and the actual gear ratio are intentionally vibrated, thereby improving the estimation accuracy of the belt slip state. It is also known to do (see, for example, Patent Document 1).

WO 2009/007450 A2 (PCT / EP2008 / 059092)

  However, the conventional belt type continuously variable transmission control device does not mention the secondary hydraulic pressure control method during belt slip control, and may cause the following problems.

  The secondary hydraulic pressure to the secondary pulley of the belt-type continuously variable transmission determines the command secondary hydraulic pressure by feedback control based on the deviation between the target secondary hydraulic pressure to obtain the required belt clamping force and the actual secondary hydraulic pressure by the sensor signal during normal control. I have control. On the other hand, at the time of belt slip control, the belt slip state is estimated using the vibration component included in the actual secondary hydraulic pressure, and control is performed based on the information. If feedback control of the secondary hydraulic pressure is maintained during belt slip control, if the actual secondary hydraulic pressure does not respond to the command secondary hydraulic pressure, the deviation for obtaining the feedback control amount increases, and the position of the actual secondary hydraulic pressure relative to the command secondary hydraulic pressure Since the phase difference is increased, the control stability of the secondary hydraulic pressure is impaired, and in some cases, the secondary hydraulic pressure control may diverge.

  The present invention has been made paying attention to the above problems, and is a belt type continuously variable transmission capable of improving the control stability of the secondary hydraulic pressure while ensuring the accuracy of estimating the belt slip state during the belt slip control. It is an object to provide a control device and a control method.

In order to achieve the above object, in the control device for a belt type continuously variable transmission according to the present invention, a primary pulley that is input from a drive source, a secondary pulley that is output to a drive wheel, and the primary pulley and the secondary pulley are spanned. A belt clamping force is controlled based on a command secondary hydraulic pressure to the secondary pulley.
The control device for the belt type continuously variable transmission includes means for switching between normal control and belt slip control, and means for controlling the secondary hydraulic pressure .
The means for switching between the normal control and the belt slip control determines whether to permit the belt slip control for reducing the secondary hydraulic pressure as compared with the normal control based on the belt slip control permission condition, and the normal control and the belt Switch between slip control .
During the normal control, the command secondary hydraulic pressure is determined by feedback control based on the deviation between the target secondary hydraulic pressure and the actual secondary hydraulic pressure, and the secondary hydraulic pressure to the secondary pulley is controlled.
During the belt slip control, the feedback control based on the deviation is prohibited, and instead of the prohibited feedback control, the secondary hydraulic pressure is vibrated, and the vibration component included in the actual secondary hydraulic pressure and the vibration component included in the actual gear ratio A belt slip state is estimated by monitoring the phase difference between the command and the command secondary oil pressure is determined so as to maintain a predetermined belt slip state based on this estimation, and the secondary oil pressure to the secondary pulley is controlled .

Therefore, in the control device for the belt type continuously variable transmission according to the present invention, based on the belt slip control permission condition, it is determined whether or not to permit the belt slip control for reducing the secondary hydraulic pressure as compared with the normal control. The normal control and the belt slip control are switched . During normal control, determine Mel the command hydraulic pressure by feedback control based on the deviation between the target oil pressure and the actual pressure. During belt slip control, feedback control based on the deviation is prohibited, and instead of the prohibited feedback control , the hydraulic pressure is vibrated, and the multiplication value (the position of the vibration component included in the actual gear ratio and the vibration component included in the actual gear ratio) is calculated. based on phase difference), determine Mel the command oil pressure for a value lower than the command hydraulic pressure by feedback control.
In this way, during belt slip control, by prohibiting feedback control based on hydraulic pressure deviation, even if the actual secondary hydraulic pressure is intentionally vibrated, the secondary hydraulic pressure control is stabilized. This makes it possible to improve the estimation accuracy of the belt slip state estimated by monitoring the phase difference between the vibration component included in the actual secondary hydraulic pressure and the vibration component included in the actual gear ratio. Further, the control does not become unstable during the belt slip control as in the case of maintaining the feedback control using the actual secondary hydraulic pressure information.
As a result, during the belt slip control, it is possible to improve the control stability of the secondary hydraulic pressure while ensuring the estimation accuracy of the belt slip state.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall system diagram showing a drive system and a control system of a vehicle equipped with a belt type continuously variable transmission to which a control device and a control method of Example 1 are applied. It is a perspective view which shows the belt-type continuously variable transmission mechanism to which the control apparatus and control method of Example 1 were applied. It is a perspective view which shows a part of belt of the belt-type continuously variable transmission mechanism to which the control apparatus and control method of Example 1 are applied. FIG. 3 is a control block diagram illustrating line pressure control and secondary hydraulic control (normal control / belt slip control) executed by the CVT control unit 8 according to the first embodiment. 6 is a basic flowchart showing a switching process between normal control of secondary hydraulic pressure and belt slip control (= “BSC”), which is executed by the CVT control unit 8 of the first embodiment. 3 is an overall flowchart illustrating a belt slip control process executed by the CVT control unit 8 according to the first embodiment. It is a flowchart which shows a torque limit process among the belt slip control processes performed in the CVT control unit 8 of Example 1. FIG. It is a flowchart which shows the vibration and correction process of secondary hydraulic pressure among the belt slip control processes performed in the CVT control unit 8 of Example 1. FIG. 3 is an overall flowchart illustrating a return process from belt slip control to normal control executed by the CVT control unit 8 according to the first embodiment. It is a flowchart which shows a torque limit process among the return processes to the normal control performed in the CVT control unit 8 of Example 1. FIG. 7 is a flowchart showing a speed ratio limiting process for a gear ratio for limiting a target primary rotational speed in a return process to a normal control executed by the CVT control unit 8 according to the first embodiment. BSC operation flag, SEC pressure F / B prohibition flag, accelerator opening, vehicle speed, engine torque, Ratio, SEC oil pressure, SEC_SOL current correction amount in the driving scene where normal control passes belt slip control / return control and returns to normal control -It is a time chart which shows each characteristic of the phase difference of SEC pressure vibration and Ratio vibration. 4 is a time chart showing characteristics of driver required torque, torque limit amount, torque capacity, and actual torque for explaining torque limit operation by torque delay adopted in the return control from belt slip control to normal control according to the first embodiment. 6 is a time chart showing characteristics of engine torque, target primary rotational speed, inertia torque, and drive shaft torque by a torque delay and a primary rotational speed increase rate limiter employed in the return control of the first embodiment.

  Hereinafter, the best mode for realizing a control device and a control method for a belt type continuously variable transmission according to the present invention will be described based on a first embodiment shown in the drawings.

First, the configuration will be described.
FIG. 1 is an overall system diagram showing a drive system and a control system of a vehicle equipped with a belt-type continuously variable transmission to which the control device and the control method of Embodiment 1 are applied. FIG. 2 is a perspective view showing a belt type continuously variable transmission mechanism to which the control device and the control method of the first embodiment are applied. FIG. 3 is a perspective view illustrating a part of the belt of the belt-type continuously variable transmission mechanism to which the control device and the control method of the first embodiment are applied. The system configuration will be described below with reference to FIGS.

  As shown in FIG. 1, the drive system of the vehicle equipped with a belt type continuously variable transmission includes an engine 1, a torque converter 2, a forward / reverse switching mechanism 3, a belt type continuously variable transmission mechanism 4, and a final reduction mechanism 5. Drive wheels 6 and 6.

  The engine 1 can control the output torque by an engine control signal from the outside, in addition to the output torque control by the accelerator operation by the driver. The engine 1 includes an output torque control actuator 10 that performs output torque control by a throttle valve opening / closing operation, a fuel cut operation, and the like.

  The torque converter 2 is a starting element having a torque increasing function. When the torque increasing function is not required, the torque converter 2 is a lockup clutch 20 that can directly connect the engine output shaft 11 (= torque converter input shaft) and the torque converter output shaft 21. Have The torque converter 2 includes a turbine runner 23 connected to the engine output shaft 11 via a converter housing 22, a pump impeller 24 connected to the torque converter output shaft 21, and a stator 26 provided via a one-way clutch 25. And are the components.

  The forward / reverse switching mechanism 3 is a mechanism that switches an input rotation direction to the belt type continuously variable transmission mechanism 4 between a forward rotation direction during forward traveling and a reverse rotation direction during backward traveling. The forward / reverse switching mechanism 3 includes a double pinion planetary gear 30, a forward clutch 31, and a reverse brake 32. The double pinion planetary gear 30 has a sun gear connected to the torque converter output shaft 21 and a carrier connected to the transmission input shaft 40. The forward clutch 31 is fastened during forward travel, and directly connects the sun gear of the double pinion planetary gear 30 and the carrier. The reverse brake 32 is fastened during reverse travel, and fixes the ring gear of the double pinion planetary gear 30 to the case.

  The belt-type continuously variable transmission mechanism 4 is a continuously variable transmission that continuously changes a gear ratio, which is a ratio of the input rotational speed of the transmission input shaft 40 and the output rotational speed of the transmission output shaft 41, by changing the belt contact diameter. It has a function. The belt type continuously variable transmission mechanism 4 includes a primary pulley 42, a secondary pulley 43, and a belt 44. The primary pulley 42 is composed of a fixed pulley 42 a and a slide pulley 42 b, and the slide pulley 42 b is slid by the primary hydraulic pressure guided to the primary hydraulic chamber 45. The secondary pulley 43 is composed of a fixed pulley 43 a and a slide pulley 43 b, and the slide pulley 43 b is slid by the primary hydraulic pressure guided to the secondary hydraulic chamber 46. As shown in FIG. 2, the belt 44 is stretched over sheave surfaces 42 c and 42 d forming a V shape of the primary pulley 42 and sheave surfaces 43 c and 43 d forming a V shape of the secondary pulley 43. As shown in FIG. 3, the belt 44 is formed by two sets of stacked rings 44a and 44a in which a large number of annular rings are stacked from the inside to the outside and a punched plate material, and is sandwiched between the two sets of stacked rings 44a and 44a. It is constituted by a large number of elements 44b that are connected to each other and provided in an annular shape. The element 44b has sheave surfaces 42c and 42d of the primary pulley 42 and flank surfaces 44c and 44c that contact the sheave surfaces 43c and 43d of the secondary pulley 43 at both side positions.

  The final reduction mechanism 5 is a mechanism that decelerates the transmission output rotation from the transmission output shaft 41 of the belt-type continuously variable transmission mechanism 4 and transmits it to the left and right drive wheels 6 and 6 while providing a differential function. The final reduction mechanism 5 is interposed in the transmission output shaft 41, the idler shaft 50, and the left and right drive shafts 51, 51, and has a first gear 52, a second gear 53, a third gear 54 having a reduction function. And a fourth gear 55 and a gear differential gear 56 having a differential function.

  As shown in FIG. 1, the control system of the vehicle equipped with a belt type continuously variable transmission includes a transmission hydraulic pressure control unit 7 and a CVT control unit 8.

  The transmission hydraulic pressure control unit 7 is a hydraulic pressure control unit that generates a primary hydraulic pressure guided to the primary hydraulic chamber 45 and a secondary hydraulic pressure guided to the secondary hydraulic chamber 46. The shift hydraulic pressure control unit 7 includes an oil pump 70, a regulator valve 71, a line pressure solenoid 72, a shift control valve 73, a pressure reducing valve 74, a secondary hydraulic solenoid 75, a servo link 76, a shift command valve 77, Step motor 78 is provided.

  The regulator valve 71 is a valve that regulates the line pressure PL using the discharge pressure from the oil pump 70 as a base pressure. The regulator valve 71 has a line pressure solenoid 72 and adjusts the pressure of the oil pumped from the oil pump 70 to a predetermined line pressure PL in response to a command from the CVT control unit 8.

  The shift control valve 73 is a valve that regulates the primary hydraulic pressure guided to the primary hydraulic chamber 45 using the line pressure PL produced by the regulator valve 71 as a source pressure. In this shift control valve 73, a spool 73a is connected to a servo link 76 constituting a mechanical feedback mechanism, and a shift command valve 77 connected to one end of the servo link 76 is driven by a step motor 78. Feedback of the slide position (actual pulley ratio) is received from the slide pulley 42b of the primary pulley 42 connected to the other end. That is, when the step motor 78 is driven in response to a command from the CVT control unit 8 at the time of shifting, the step motor 78 supplies / discharges the line pressure PL to / from the primary hydraulic chamber 45 by the displacement of the spool 73a of the shift control valve 73. The primary hydraulic pressure is adjusted so that the target gear ratio commanded at the drive position is obtained. When the shift is completed, the spool 73a is held in the closed position in response to the displacement from the servo link 76.

  The pressure reducing valve 74 is a valve that adjusts the secondary hydraulic pressure guided to the secondary hydraulic chamber 46 by the pressure reducing control using the line pressure PL generated by the regulator valve 71 as a source pressure. The pressure reducing valve 74 includes a secondary hydraulic solenoid 75 and reduces the line pressure PL in accordance with a command from the CVT control unit 8 to control it to the command secondary hydraulic pressure.

  The CVT control unit 8 outputs a control command for obtaining a target speed ratio corresponding to the vehicle speed, throttle opening, etc. to the step motor 78, and a control command for obtaining a target line pressure corresponding to the throttle opening, etc. Line pressure control to be output to the pressure solenoid 72, secondary hydraulic control to output a control command for obtaining the target secondary pulley thrust according to the transmission input torque, etc. to the secondary hydraulic solenoid 75, engagement / release of the forward clutch 31 and the reverse brake 32 For example, forward / reverse switching control for controlling, lockup control for controlling engagement / release of the lockup clutch 20, and the like are performed. The CVT control unit 8 includes a primary rotation sensor 80, a secondary rotation sensor 81, a secondary oil pressure sensor 82, an oil temperature sensor 83, an inhibitor switch 84, a brake switch 85, an accelerator opening sensor 86, other sensors and switches 87, and the like. Sensor information and switch information are input. Further, torque information is input from the engine control unit 88 and a torque request is output to the engine control unit 88.

  FIG. 4 is a control block diagram illustrating line pressure control and secondary hydraulic pressure control (normal control / belt slip control) executed by the CVT control unit 8 according to the first embodiment.

  As shown in FIG. 4, the hydraulic control system of the CVT control unit 8 according to the first embodiment includes a basic hydraulic pressure calculation unit 90, a line pressure control unit 91, a secondary hydraulic pressure control unit 92, and a sine wave excitation control unit 93. A secondary hydraulic pressure correction unit 94.

  The basic hydraulic pressure calculation unit 90 includes an input torque calculation unit 90a that calculates transmission input torque based on torque information (engine speed, fuel injection time, etc.) from the engine control unit 88 (see FIG. 1), and an input. A basic secondary thrust calculation unit 90b that calculates a basic secondary thrust (belt clamping force required for the secondary pulley 43) from the transmission input torque obtained by the torque calculation unit 90a, and a differential thrust (primary pulley 42 and secondary pulley required for shifting) 43) (difference in belt clamping force of 43), a required difference thrust calculating unit 90c for shifting, a correcting unit 90d for correcting the calculated basic secondary thrust based on the required differential thrust during shifting, and the corrected secondary thrust as the target secondary hydraulic pressure A secondary hydraulic pressure conversion unit 90e for converting to Furthermore, a basic primary thrust calculation unit 90f that calculates a basic primary thrust (a belt clamping force necessary for the primary pulley 42) from the transmission input torque obtained by the input torque calculation unit 90a, and the calculated basic primary thrust are necessary for shifting. A correction unit 90g that corrects based on the required differential thrust during shifting calculated by the differential thrust calculation unit 90c, and a primary hydraulic pressure conversion unit 90h that converts the corrected primary thrust into the target primary hydraulic pressure.

  The line pressure control unit 91 compares the target primary hydraulic pressure output from the primary hydraulic pressure conversion unit 90h with the indicated secondary hydraulic pressure obtained from the secondary hydraulic pressure control unit 92, and when the target primary hydraulic pressure ≧ the indicated secondary hydraulic pressure, A target line pressure determining unit 91a that sets the target line pressure to the same value as the commanded secondary hydraulic pressure when the line pressure is set to the same value as the target primary hydraulic pressure and the target primary hydraulic pressure is less than the commanded secondary hydraulic pressure; A hydraulic pressure-current conversion unit 91b that converts the target line pressure determined in 91a into a current value to be applied to the solenoid and outputs the converted command current value to the line pressure solenoid 72 of the regulator valve 71.

  The secondary hydraulic pressure control unit 92 obtains an instruction secondary hydraulic pressure by feedback control (PI control) using the actual secondary hydraulic pressure detected by the secondary hydraulic pressure sensor 82 during normal control, and uses the actual secondary hydraulic pressure during belt slip control. The commanded secondary hydraulic pressure is obtained by open control without any. A low-pass filter 92a that filters the target secondary hydraulic pressure from the secondary hydraulic pressure conversion unit 90e, a deviation calculation unit 92b that calculates a deviation between the actual secondary hydraulic pressure and the target secondary hydraulic pressure, a zero deviation setting unit 92c that sets deviation = 0, There is a deviation switching unit 92d that selects and switches between the calculated deviation and the zero deviation, and an integral gain determination unit 92e that determines an integral gain based on the oil temperature. The multiplier 92f that multiplies the integral gain from the integral gain determination unit 92e and the deviation from the deviation switching unit 92d, the integrator 92g that integrates the FB integral control amount from the multiplier 92f, and the secondary hydraulic pressure conversion unit 90e. An adder 92h for adding the FB integral control amount integrated to the target secondary hydraulic pressure, and an instruction secondary hydraulic pressure (referred to as "basic secondary hydraulic pressure" during belt slip control) by applying an upper / lower limiter to the added value. And a limiter 92i to be obtained. Further, during belt slip control, a vibration adder 92j that applies a sinusoidal vibration command to the basic secondary hydraulic pressure, a hydraulic pressure corrector 92k that corrects the excited basic secondary hydraulic pressure with a secondary hydraulic pressure correction amount to obtain an instruction secondary hydraulic pressure, A hydraulic-current conversion unit 92m that converts the command secondary hydraulic pressure into a current value to be applied to the solenoid, and outputs the converted command current value to the secondary hydraulic solenoid 75 of the pressure reducing valve 74; The deviation switching unit 92d selects the calculated deviation when the BSC operation flag = 0 (during normal control), and selects the zero deviation when the BSC operation flag = 1 (during belt slip control).

  The sine wave excitation control unit 93 determines an oscillating frequency and an oscillating amplitude suitable for belt slip control, a sine wave exciter 93a for applying a sine wave hydraulic vibration with the determined frequency and amplitude, and a sine wave hydraulic pressure. It has a zero vibration setting device 93b that applies no vibration and a vibration switching unit 93c that selects and switches between sine wave hydraulic vibration and zero vibration. In the vibration switching unit 93c, zero vibration is selected when the BSC operation flag = 0 (during normal control), and sine wave hydraulic vibration is selected when the BSC operation flag = 1 (during belt slip control). .

  The secondary hydraulic pressure correction unit 94 includes an actual transmission ratio calculation unit 94a that calculates an actual transmission ratio Ratio based on a ratio between the primary rotational speed Npri from the primary rotational sensor 80 and the secondary rotational speed Nsec from the secondary rotational sensor 81, and a secondary hydraulic sensor. The first bandpass filter 94b that extracts the vibration component from the signal that represents the actual secondary hydraulic pressure Psec acquired by 82, and the second bandpass filter 94c that extracts the vibration component from the calculation data acquired by the actual gear ratio calculation unit 94a. And having. And based on the phase difference information from the multiplier 94d which multiplies the vibration component extracted by both the band pass filters 94b and 94c, the low-pass filter 94e which extracts phase difference information from the multiplication result, and the low-pass filter 94e. A secondary hydraulic pressure correction amount determination unit 94f that determines a secondary hydraulic pressure correction amount, a zero correction amount setting unit 94g that sets a secondary hydraulic pressure zero correction amount, and a correction that selects and switches between the secondary hydraulic pressure correction amount and the zero correction amount A quantity switching unit 94h. The correction amount switching unit 94h selects the zero correction amount when the BSC operation flag = 0 (during normal control) and the secondary hydraulic pressure correction amount determined when the BSC operation flag = 1 (during belt slip control). Is done.

  FIG. 5 is a basic flowchart showing a switching process between the normal control of the secondary hydraulic pressure and the belt slip control (= “BSC”) executed by the CVT control unit 8 according to the first embodiment. Hereinafter, each step of FIG. 5 will be described.

  In step S1, normal control of the belt-type continuously variable transmission mechanism 4 is performed following start by key-on, determination of BSC disapproval in step S2, or normal control return processing in step S5, and the process proceeds to step S2. . During normal control, the BSC operation flag = 0 is set and the secondary pressure F / B prohibition flag is set to zero.

In step S2, following the normal control in step S1, it is determined whether or not all of the following BSC permission conditions are satisfied. If YES (all BSC permission conditions are satisfied), the process proceeds to step S3 and belt slip control ( BSC). If NO (there is a condition that does not satisfy even one of the BSC permission conditions), the process returns to step S1 to continue normal control.
Here, an example of the BSC permission condition is shown below.
(1) The transmission torque capacity of the belt type continuously variable transmission mechanism 4 is stable (the rate of change of the transmission torque capacity is small).
This condition (1) is, for example,
a. | Command torque change rate | <predetermined value
b. Judgment based on two conditions: | command speed ratio change rate | <predetermined value.
(2) The estimation accuracy of the input torque to the primary pulley 42 is within a reliable range.
The condition (2) is determined based on, for example, torque information (estimated engine torque) from the engine control unit 88, the lock-up state of the torque converter 2, the operation state of the brake pedal, the range position, and the like.
(3) Continue the permission states (1) and (2) above for a predetermined time.
In step S2, it is determined whether or not all of the above conditions (1), (2), and (3) are satisfied.

  In step S3, following the BSC permission determination in step S2 or the BSC continuation determination in step S4, the input to the belt 44 of the belt type continuously variable transmission mechanism 4 is reduced, and the belt 44 is not slipped. Belt slip control (FIGS. 6 to 8) for maintaining a smooth slip state is performed, and the process proceeds to step S4. During the belt slip control, the BSC operation flag = 1 is set and the secondary pressure F / B prohibition flag is set to “1”.

In step S4, following the belt slip control in step S3, it is determined whether or not all the following BSC continuation conditions are satisfied. If YES (all the BSC continuation conditions are satisfied), the process returns to step S3, and the belt slip control is performed. Continue (BSC). If NO (there is a condition that does not satisfy even one of the BSC continuation conditions), the process proceeds to step S5, and normal control return processing is performed.
Here, an example of the BSC continuation condition is shown below.
(1) The transmission torque capacity of the belt type continuously variable transmission mechanism 4 is stable (the rate of change of the transmission torque capacity is small).
This condition (1) is, for example,
a. | Command torque change rate | <predetermined value
b. Judgment based on two conditions: | command speed ratio change rate | <predetermined value.
(2) The estimation accuracy of the input torque to the primary pulley 42 is within a reliable range.
The condition (2) is determined based on, for example, torque information (estimated engine torque) from the engine control unit 88, the lock-up state of the torque converter 2, the operation state of the brake pedal, the range position, and the like.
It is determined whether or not both of the above conditions (1) and (2) are satisfied.
That is, the difference between the BSC permission condition and the BSC continuation condition is that the BSC continuation condition does not have the continuation condition (3) among the BSC permission conditions.

  In step S5, following the determination that one of the BSC continuation conditions in step S4 does not satisfy one of the conditions, a normal control return process for preventing the belt 44 from slipping when returning from belt slip control to normal control ( 9 to 11) are performed, and after the process is completed, the process returns to step S1 to shift to the normal control.

  FIG. 6 is an overall flowchart illustrating a belt slip control process executed by the CVT control unit 8 according to the first embodiment. FIG. 7 is a flowchart showing the torque limit process in the belt slip control process executed by the CVT control unit 8 of the first embodiment. FIG. 8 is a flowchart showing the secondary oil pressure excitation / correction process in the belt slip control process executed by the CVT control unit 8 according to the first embodiment.

  First, as apparent from FIG. 6, during the belt slip control in which the BSC continuation determination is maintained from the BSC permission determination, the feedback control prohibition process (step S31) for obtaining the command secondary hydraulic pressure using the actual secondary hydraulic pressure, A torque limit process (step S32) in preparation for returning to the control and a secondary oil pressure excitation / correction process (step S33) for belt slip control are performed simultaneously.

In step S31, during the belt slip control in which the BSC continuation determination is maintained from the BSC permission determination, feedback control for obtaining the command secondary hydraulic pressure using the actual secondary hydraulic pressure detected by the secondary hydraulic pressure sensor 82 is prohibited.
That is, when obtaining the command secondary oil pressure, the feedback control during the normal control is prohibited and the control is switched to the open control using the zero deviation during the belt slip control. When the belt slip control is shifted to the normal control, the control returns to the feedback control again.

In step S32, the torque limit process of FIG. 7 is performed during the belt slip control in which the BSC continuation determination is maintained from the BSC permission determination.
That is, in the flowchart of FIG. 7, in step S321, “torque limit request from belt slip control” is set as the driver request torque.

  In step S33, during the belt slip control in which the BSC continuation determination is maintained from the BSC permission determination, the secondary hydraulic pressure in FIG. Hereinafter, each step of the flowchart of FIG. 8 will be described.

  In step S331, the command secondary hydraulic pressure is vibrated. That is, a sine wave hydraulic pressure with a predetermined amplitude and a predetermined frequency is superimposed on the command secondary hydraulic pressure, and the process proceeds to step S332.

  In step S332, following the excitation of the command secondary hydraulic pressure in step S331, the actual secondary hydraulic pressure is detected from the secondary hydraulic sensor 82, and the actual gear ratio is determined based on the rotational speed information from the primary rotation sensor 80 and the secondary rotation sensor 81. It detects by calculation and progresses to step S333.

In step S333, following the detection of the actual secondary hydraulic pressure and the actual gear ratio in step S332, bandpass filter processing is performed on each of the actual secondary hydraulic pressure and the actual gear ratio, and vibration components (sine Wave), multiplied and multiplied, and the multiplication value is subjected to low-pass filter processing to obtain a value represented by the amplitude and the phase difference θ (cosine wave) from the actual secondary hydraulic vibration to the actual gear ratio vibration. Convert to step S334.
Here, assuming that the actual secondary hydraulic pressure amplitude is A and the actual gear ratio amplitude is B,
Actual secondary hydraulic vibration: Asinωt (1)
Actual gear ratio vibration: Bsin (ωt + θ) (2)
It is represented by
Multiplying (1) and (2) is the sum of products formula
sinαsinβ = -1 / 2 {cos (α + β) -cos (α-β)} (3)
Using
Asinωt × Bsin (ωt + θ) = (1/2) ABcosθ− (1/2) ABcos (2ωt + θ) (4)
It becomes.
In the above equation (4), when the low-pass filter is passed, (1/2) ABcos (2ωt + θ), which is a component twice the excitation frequency, is reduced.
Asinωt × Bsin (ωt + θ) ≒ (1/2) ABcosθ (5)
Thus, the amplitudes A and B and the phase difference θ from the actual secondary hydraulic vibration to the actual gear ratio vibration can be expressed.

  In step S334, following the calculation of the phase difference θ from the actual secondary hydraulic vibration to the actual gear ratio vibration in step S333, the phase difference θ from the actual secondary hydraulic vibration to the actual gear ratio vibration is 0 ≦ phase difference θ <predetermined. It is determined whether or not the value is 1 (micro slip region). If YES (0 ≦ phase difference θ <predetermined value 1), the process proceeds to step S335. If NO (predetermined value 1 ≦ phase difference θ), the process proceeds to step S335. Proceed to S336.

  In step S335, following the determination in step S334 that 0 ≦ phase difference θ <predetermined value 1 (micro slip region), the secondary hydraulic pressure correction amount is set to “−ΔPsec”, and the process proceeds to step S339.

  In step S336, following the determination that the predetermined value 1 ≦ phase difference θ in step S334, the phase difference θ from the actual secondary hydraulic vibration to the actual gear ratio vibration is a predetermined value 1 ≦ phase difference θ <predetermined value 2 It is determined whether or not (target slip region). If YES (predetermined value 1 ≦ phase difference θ <predetermined value 2), the process proceeds to step S337. If NO (predetermined value 2 ≦ phase difference θ), the process proceeds to step S337. Proceed to S338.

  In step S337, following the determination that predetermined value 1 ≦ phase difference θ <predetermined value 2 (target slip region) in step S336, the secondary hydraulic pressure correction amount is set to “0”, and the process proceeds to step S339.

  In step S338, following the determination in step S336 that the predetermined value 2 ≦ phase difference θ (micro / macro slip transition region), the secondary hydraulic pressure correction amount is set to “+ ΔPsec”, and the process proceeds to step S339.

  In step S339, following the setting of the secondary hydraulic pressure correction amount in steps S335, S337, and S338, the basic secondary hydraulic pressure + secondary hydraulic pressure correction amount is set as the command secondary hydraulic pressure, and the process proceeds to the end.

  FIG. 9 is an overall flowchart illustrating a return process from the belt slip control to the normal control executed by the CVT control unit 8 according to the first embodiment. FIG. 10 is a flowchart showing the torque limit process in the return process to the normal control executed by the CVT control unit 8 according to the first embodiment. FIG. 11 is a flowchart showing a speed ratio limiting process of a gear ratio for limiting the target primary rotational speed in the return process to the normal control executed by the CVT control unit 8 according to the first embodiment.

  First, as is clear from FIG. 9, during the return from the belt slip control to the normal control from the BSC continuation stop to the start of the normal control, the feedback control return processing for obtaining the indicated secondary hydraulic pressure using the actual secondary hydraulic pressure ( Step S51), torque limit processing for returning to normal control (Step S52), secondary oil pressure excitation / correction reset processing for belt slip control (Step S53), and shift regulation for regulating the shift speed The process (step S54) is performed simultaneously.

  In step S51, during the return from the belt slip control to the normal control until the normal control is started after the BSC continuation is stopped, the control returns to the feedback control for obtaining the command secondary hydraulic pressure using the actual secondary hydraulic pressure detected by the secondary hydraulic pressure sensor 82. To do.

  In step S52, during the return from the belt slip control to the normal control from the BSC continuation stop to the start of the normal control, the torque limit process toward the return to the normal control in FIG. 10 is performed.

  In step S53, during the return from the belt slip control to the normal control until the normal control is started after the BSC continuation is stopped, the secondary oil pressure excitation / correction in FIG. 8 is reset to prepare for the normal control.

  In step S54, a shift restriction process for restricting the shift speed in FIG. 11 is performed during the return from the belt slip control to the normal control from the BSC continuation stop to the start of the normal control.

Hereinafter, each step of the flowchart showing the torque limit process of FIG. 10 will be described. In this torque limit process, the point is that the control is switched based on the magnitude relationship of three values of “driver required torque”, “torque limit request from BSC”, and “torque capacity (calculated torque capacity)”. “Driver required torque” is the engine torque requested by the driver. The “torque limit request from BSC” is the torque limit amount in the phases (2) and (3) in FIG. “Torque capacity” is usually a design allowable torque capacity (phase (1) in FIG. 13), and safety that takes into account the mechanical variation of the belt-type continuously variable transmission mechanism 4 to prevent belt slippage. This value is set higher than the driver required torque by the margin. Here, the actual torque capacity is controlled by secondary hydraulic control.
Furthermore, the “calculated torque capacity” is the torque capacity during BSC (phase (2) in FIG. 13) and during the return process (phase (3) in FIG. 13). This calculated torque capacity is a value based on the actual secondary oil pressure and the actual gear ratio, and specifically, a value calculated based on the actual secondary oil pressure and the actual gear ratio (the engine torque of the two pulleys 42 and 43). On the side from which the gear enters, that is, the torque capacity at the primary pulley 42).

  In step S521, it is determined whether or not “driver required torque” is larger than “torque limit request from BSC”. If YES, the process proceeds to step S522, and if NO, the process proceeds to step S525.

  In step S522, following the determination that “driver required torque”> “torque limit request from BSC” in step S521, it is determined whether “calculated torque capacity” is greater than “torque limit request from BSC”. If YES, the process proceeds to step S523, and if NO, the process proceeds to step S524.

  In step S523, following the determination that “calculated torque capacity”> “torque limit request from BSC” in step S522, “torque limit request from BSC” is changed to “torque limit request from BSC (previous value). ) + ΔT ”and“ calculated allowable torque capacity ”, set to the smaller value and proceed to return.

  In step S524, following the determination in step S522 that “calculated torque capacity” ≦ “torque limit request from BSC”, “torque limit request from BSC” is changed to “torque limit request from BSC (previous value). ) ”And“ Driver Required Torque ”, set to the smaller value and proceed to return.

  In step S525, following the determination that “driver required torque” ≦ “torque limit request from BSC” in step S521, it is determined whether or not “calculated torque capacity” is greater than “torque limit request from BSC”. If YES, the process proceeds to step S527. If NO, the process proceeds to step S526.

  In step S526, following the determination that “calculated torque capacity” ≦ “torque limit request from BSC” in step S525, “torque limit request from BSC” is changed to “torque limit request from BSC (previous value). ) ”And“ Driver Required Torque ”, set to the smaller value and proceed to return.

  In step S527, following the determination that “calculated torque capacity”> “torque limit request from BSC” in step S525, “torque limit from BSC” is canceled, and the process proceeds to the end.

  Hereinafter, each step of the flowchart showing the speed ratio limiting process of the speed ratio for limiting the target primary rotation speed in FIG. 11 will be described.

  In step S541, the target inertia torque is calculated from the engine torque, and the process proceeds to step S542.

  In step S542, following the calculation of the target inertia torque in step S541, the target primary rotation change rate is calculated by the target inertia torque, and the process proceeds to step S543.

  In step S543, following the calculation of the target primary rotation change rate in step S542, a limited target primary rotation speed that does not exceed the target primary rotation change rate is calculated, and the process proceeds to step S544.

  In step S544, following the calculation of the limited target primary rotation speed in step S543, shift control is performed based on the limited target primary rotation speed, and the process proceeds to step S545.

  In step S545, following the shift control in step S544, it is determined whether or not the shift control based on the limited target primary rotational speed has been completed, that is, whether or not the actual primary rotational speed has reached the limited target primary rotational speed. . If YES (end of shift control), the process proceeds to the end. If NO (during shift control), the process returns to step S541.

Next, the operation will be described.
The operations of the control device and the control method of the belt type continuously variable transmission mechanism 4 of the first embodiment are as follows: “BSC permission determination operation and BSC continuation determination operation”, “belt slip control operation (BSC operation)”, “secondary hydraulic pressure during BSC” The feedback control prohibiting action ”,“ torque limit action in return control from BSC to normal control ”, and“ primary rotation increase rate limit action in return control from BSC to normal control ”will be described separately.

[BSC permission judgment action and BSC continuation judgment action]
When the vehicle starts to travel, in the flowchart of FIG. 5, the process proceeds from step S1 to step S2, and unless all the BSC permission determination conditions in step S2 are satisfied, the flow from step S1 to step S2 is repeated. Control is maintained. That is, satisfying all of the BSC permission determination conditions in step S2 is a BSC control start condition.

Here, the BSC permission conditions in the first embodiment will be described below.
(1) The transmission torque capacity of the belt type continuously variable transmission mechanism 4 is stable (the rate of change of the transmission torque capacity is small).
This condition (1) is, for example,
a. | Command torque change rate | <predetermined value
b. Judgment based on two conditions: | command speed ratio change rate | <predetermined value.
(2) The estimation accuracy of the input torque to the primary pulley 42 is within a reliable range.
The condition (2) is determined based on, for example, torque information (estimated engine torque) from the engine control unit 88, the lock-up state of the torque converter 2, the operation state of the brake pedal, the range position, and the like.
(3) Continue the permission states (1) and (2) above for a predetermined time.
In step S2, it is determined whether or not all of the above conditions (1), (2), and (3) are satisfied.

  Therefore, during normal control, when the transmission torque capacity of the belt-type continuously variable transmission mechanism 4 is stable and the estimated accuracy of the input torque to the primary pulley 42 is within a reliable range continues for a predetermined time. The start of belt slip control is permitted.

  Thus, since the start of the belt slip control is permitted by satisfying all of the BSC permission conditions, the belt slip control can be started in a preferable adaptive region in which high control accuracy is guaranteed.

  When the BSC permission determination is made in step S2, the process proceeds to step S3, where the belt type continuously variable transmission mechanism 4 is reduced in input to the belt 44, and the belt that keeps an appropriate slip state without slipping the belt 44. Slip control is performed. Then, following the belt slip control in step S3, in the next step S4, it is determined whether or not all the BSC continuation conditions are satisfied. As long as all the BSC continuation conditions are satisfied, the flow proceeds from step S3 to step S4. Repeatedly, the belt slip control (BSC) is continued.

Here, as the BSC continuation condition in the first embodiment, the conditions (1) and (2) among the BSC permission conditions are used. That is, among the BSC permission conditions, the predetermined time continuation condition (3) is not included in the BSC continuation conditions.
For this reason, during belt slip control, if one of the conditions (1) and (2) is not satisfied, the belt slip control is stopped immediately and the normal control is resumed, so the control accuracy is not guaranteed. Thus, it is possible to prevent the belt slip control from being continued.

[Belt slip control action (BSC action)]
At the start of the belt slip control, since the secondary hydraulic pressure is obtained by estimating the safety factor and obtaining a clamping force without belt slip, the condition that the phase difference θ is less than the predetermined value 1 is satisfied. In the flowchart of FIG. The flow from S331 → step S332 → step S333 → step S334 → step S335 → step S339 is repeated, and each time this flow is repeated, the command secondary hydraulic pressure is reduced by the correction of −ΔPsec. When the phase difference θ is equal to or greater than the predetermined value 1, until the phase difference θ reaches the predetermined value 2, in the flowchart of FIG. 8, step S331 → step S332 → step S333 → step S334 → step S336 → step S337 → step The flow proceeds to S339, and the command secondary hydraulic pressure is maintained. Then, when the phase difference θ becomes equal to or larger than the predetermined value 2, in the flowchart of FIG. 8, the flow proceeds from step S331 → step S332 → step S333 → step S334 → step S336 → step S338 → step S339. Ascends after correction of + ΔPsec.
That is, in the belt slip control, control is performed to maintain a slip ratio that is in a range where the phase difference θ is not less than the predetermined value 1 and less than the predetermined value 2.

The belt slip control will be described with reference to the time chart shown in FIG.
First, the BSC permission conditions (1) and (2) are satisfied at time t1, and the BSC permission conditions (1) and (2) continue (BSC permission conditions (3)). When reaching, the BSC operation flag and the SEC pressure F / B prohibition flag (secondary pressure feedback) from time t2 to time t3 when at least one of the BSC continuation conditions (1) and (2) is not satisfied. Prohibition flag) is set, and belt slip control is performed. If at least one of the BSC continuation conditions is not satisfied due to the accelerator depressing operation slightly before time t3, the return control to the normal control is performed from time t3 to time t4, and after time t4. Normal control will be performed.

  In this way, as is apparent from the accelerator opening characteristic, the vehicle speed characteristic, and the engine torque characteristic, the belt slip control is performed with the solenoid current correction amount characteristic to the secondary hydraulic solenoid 75 during the steady running determination indicated by the arrow C in FIG. As shown, the phase difference θ between the vibration component of the secondary hydraulic pressure and the vibration component of the gear ratio that appears as a result of exciting the secondary hydraulic pressure is monitored, and the current value is increased or decreased. The secondary hydraulic solenoid 75 is normally open (normally open), and when the current value is increased, the secondary hydraulic pressure is decreased.

  By this belt slip control, the actual gear ratio is maintained substantially constant although it vibrates with a small amplitude as shown in the actual gear ratio characteristic (Ratio) of FIG. Then, as shown in the phase difference characteristic between the SEC pressure vibration and the Ratio vibration in FIG. 12, the phase difference θ gradually increases as the slip ratio gradually increases from time t2 when the slip ratio is close to zero. The characteristic which converges to (target slip ratio) is shown. Then, as shown in the SEC hydraulic characteristics of FIG. 12, the secondary hydraulic pressure decreases as indicated by an arrow G as time elapses from time t2 having a safety factor, and finally reaches the minimum design pressure. The hydraulic pressure amplitude is added, and the characteristic converges to a sufficient hydraulic pressure level with respect to the actual minimum pressure. When the belt slip control continues for a long time, the actual secondary hydraulic pressure in the design minimum pressure + hydraulic amplitude range is maintained so as to maintain the target value of the phase difference θ (the target value of the slip ratio). .

  Thus, by reducing the secondary hydraulic pressure by belt slip control, the belt friction acting on the belt 44 is reduced, and the drive load for driving the belt-type continuously variable transmission mechanism 4 can be kept low by the reduction in belt friction. . As a result, the fuel efficiency of the engine 1 can be improved without affecting the running performance during the belt slip control by the BSC permission determination.

[Secondary hydraulic feedback control prohibition during BSC]
During the belt slip control from the start to the end of the belt slip control, the command secondary hydraulic pressure is obtained by open control without using the actual secondary hydraulic pressure, and the feedback control prohibiting action for prohibiting the feedback control of the command secondary hydraulic pressure will be described. .

  First, regardless of whether it is during normal control or belt slip control, the deviation calculation unit 92b of the secondary hydraulic control unit 92 uses the actual secondary hydraulic pressure based on the pressure signal from the secondary hydraulic sensor 82 and the target through the low-pass filter 92a. The deviation of the secondary hydraulic pressure is calculated.

  Then, during normal control, as shown in FIG. 4, since the BSC operation flag = 0, the calculated deviation side is selected in the deviation switching unit 92d of the secondary hydraulic control unit 92. Therefore, the integral gain from the integral gain determining unit 92e and the deviation from the deviation calculating unit 92b are multiplied by the multiplier 92f to calculate the FB integral control amount, and the FB integral control amount is integrated in the next integrator 92g. The The adder 92h adds the FB integral control amount integrated with the target secondary hydraulic pressure from the secondary hydraulic pressure conversion unit 90e and the FB proportional control amount (omitted), and the limiter 92i applies an upper / lower limiter to the added value. Instructed secondary hydraulic pressure is obtained. That is, the instruction secondary hydraulic pressure is obtained by feedback control (PI control) using the actual secondary hydraulic pressure detected by the secondary hydraulic pressure sensor 82.

  On the other hand, since the BSC operation flag = 1 at the time of belt slip control, the zero deviation side is selected in the deviation switching unit 92d of the secondary hydraulic pressure control unit 92. Therefore, the integral gain and the zero deviation from the integral gain determining unit 92e are multiplied by the multiplier 92f, but the FB integral control amount is calculated as a zero value. In the next integrator 92g, the FB integral control amount is integrated. Even if this is done, the FB integral control amount immediately before entering the belt slip control is held only by integrating the zero value. The adder 92h adds the feedback control amount (= FB integral control amount) accumulated until the previous time to the target secondary hydraulic pressure from the secondary hydraulic pressure conversion unit 90e, and the limiter 92i increases the added value. An instruction secondary hydraulic pressure is obtained by applying a lower limiter. That is, the instruction secondary hydraulic pressure is obtained by open control without using the actual secondary hydraulic pressure by setting the zero deviation.

  For example, when the instruction secondary hydraulic pressure is obtained by feedback control using actual secondary hydraulic pressure information during belt slip control, the deviation varies depending on the vibration component included in the actual secondary hydraulic pressure, and the feedback control amount corresponding to this deviation is continuously added. Therefore, the secondary hydraulic control becomes unstable. In particular, in the belt slip control, when the actual secondary hydraulic pressure is vibrated at a single frequency, the secondary hydraulic pressure by the feedback control may diverge.

  Generally, whether or not the actual secondary hydraulic pressure diverges is determined by the hydraulic feedback control, the frequency response of the shift control, and the hardware response. For this reason, when the secondary hydraulic pressure is vibrated at a single frequency, the frequency response of the hydraulic feedback control and the shift control is taken into consideration, and the vibration frequency is set, or the hydraulic feedback control and the shift control are adjusted according to the vibration frequency. It is necessary to determine the frequency response. However, no matter which method is adopted, the control itself becomes complicated.

  On the other hand, in the first embodiment, since the actual secondary hydraulic pressure information is not used during the belt slip control, the actual secondary hydraulic pressure is allowed to include a vibration component or intentionally include the vibration component. In other words, the estimation accuracy of the belt slip state estimated by monitoring the phase difference θ between the vibration component included in the actual secondary hydraulic pressure and the vibration component included in the actual gear ratio is ensured. In particular, even if the actual secondary hydraulic pressure is vibrated, the secondary hydraulic pressure control is not affected, so that the phase difference θ between the vibration component included in the actual secondary hydraulic pressure and the vibration component included in the actual gear ratio can be clearly obtained. By monitoring this phase difference θ, the region immediately before the belt slip can be reliably determined.

  In addition, in the first embodiment, during the belt slip control, the secondary hydraulic control is an open control that does not use the feedback information (actual secondary hydraulic information), and therefore the secondary hydraulic control by the feedback control is maintained during the belt slip control. As described above, it is possible to prevent the control from becoming unstable or the control from diverging.

  Further, in the secondary hydraulic control of the first embodiment, during the belt slip control, only the deviation is set to zero, the feedback control amount until immediately before the transition to the belt slip control is held, and the secondary hydraulic pressure is used by using the held constant feedback control amount. Open control is performed.

  For example, if open control with zero feedback control amount is performed during belt slip control, a feedback control amount with a large value including a steady deviation is added to the target secondary hydraulic pressure at the time of transition from belt slip control to normal control. Therefore, a discontinuous drop occurs in the secondary hydraulic pressure depending on the presence or absence of the feedback control amount, and if the hydraulic pressure drop is large, there is a possibility of a shock that gives the passenger a sense of discomfort.

  On the other hand, during belt slip control, only the deviation is set to zero and secondary oil pressure open control is performed using a constant feedback control amount. Therefore, as indicated by an arrow H in FIG. Prevents the passenger from feeling uncomfortable due to a drop in the secondary hydraulic pressure when returning from the open control to the feedback control so that the secondary hydraulic pressure rises smoothly and continuously in the region of time t3 can do.

[Torque limit action in return control from BSC to normal control]
In step S32 in FIG. 6, during the belt slip control in which the BSC continuation determination is maintained from the BSC permission determination, in step S321 in FIG. 7, “torque limit request from belt slip control” is set as the driver request torque. Torque limit processing is performed. Hereinafter, the torque limit operation when returning to the normal control will be described with reference to FIGS. 10 and 13.

First, the engine control unit 88 has a torque limit amount as an engine torque upper limit for control. As a result, the actual torque of the engine 1 is limited so as not to exceed the torque limit.
This torque limit amount is determined by various requirements. For example, as a request from the belt-type continuously variable transmission mechanism 4, the upper limit of the input torque of the belt-type continuously variable transmission mechanism 4 during normal control (phase (1) in FIG. 13) is set as “torque limit request during normal control”. The CVT control unit 8 transmits this “torque limit request during normal control” to the engine control unit 88. In this way, the engine control unit 88 selects the minimum one of the plurality of “torque limit requests” required from various controllers as the torque limit amount.

That is, when the belt slip control is entered from the normal control phase (1) at time t5, as shown in the torque limit amount characteristic of FIG. 13, in the phase (2), “torque limit request from BSC” is engine control. Sent to unit 88.
However, “torque limit request from BSC” during BSC (phase (2) in FIG. 13) is a preliminary preparation for torque limit in FIG. 10, and during BSC (phase (2) in FIG. 13) In fact, it does not function as a torque limit.

  When the BSC continuation is stopped at time t6 and the control to return to the normal control is entered, at time t6, the driver request torque> the torque limit request from BSC and the calculated torque capacity ≦ the torque limit request from BSC. Therefore, in the flowchart of FIG. 10, the flow of going from step S521 → step S522 → step S524 → return is repeated, and in step S524, the torque limit request (previous value) from the BSC is maintained.

  Thereafter, the driver request torque> the torque limit request from the BSC, but from the time t7 when the calculated torque capacity> the torque limit request from the BSC, in the flowchart of FIG. 10, go to step S521 → step S522 → step S523 → return. In step S523, the torque limit request from the BSC is set to (previous value + ΔT), and the torque limit request from the BSC gradually increases. The actual torque also follows this increasing gradient. Rise gradually.

  After that, since “torque limit request from BSC” rises from time t7, at time t8 when the torque limit request from driver required torque ≦ BSC, the calculated torque capacity> the torque limit request from BSC. In the flowchart of FIG. 10, the process proceeds from step S521 to step S525 to step S527 to end, and in step S527, the torque limit from the BSC is released.

  In this example, step S526 is not passed, but step S526 is passed when the accelerator operation such as stepping on the accelerator or returning the accelerator (seeding off) is performed in a short time. That is, when the accelerator pedal is released and the belt slip control is released and the return control is entered, the accelerator foot release operation is performed, and thus step S526 is passed.

  That is, in the belt slip control, since the belt is actively slid within the allowable slip range, the belt clamping force is lower than that in the normal control. When returning from the belt slip control to the normal control, if the input torque to the belt-type continuously variable transmission mechanism 4 changes in the increasing direction, the input torque exceeds the belt clamp force, which may cause excessive belt slip.

  On the other hand, during the transition period from the belt slip control to the normal control, the input that changes in the increasing direction is maintained such that the actual torque at the end of the belt slip control is maintained from time t6 to time t7 in FIG. By limiting the torque change speed and suppressing the increase in input torque, the input torque to the belt type continuously variable transmission mechanism 4 is reduced while the belt clamping force at the end of the belt slip control is restored to the level during normal control. It is suppressed that the belt clamping force becomes excessive.

  Therefore, when the belt slip control is returned to the normal control, torque limit control is performed to limit the change speed of the input torque to the belt-type continuously variable transmission mechanism 4, so that the input torque to the belt-type continuously variable transmission mechanism 4 Excessive with respect to the clamping force can be suppressed, and slippage of the belt 44 can be prevented.

  In particular, in the first embodiment, the torque limit control for holding the input torque to the belt type continuously variable transmission mechanism 4 at the end of the belt slip control is performed. Therefore, it is possible to reliably prevent the input torque from becoming excessive with respect to the belt clamping force.

[Primary rotation increase rate limit action in return control from BSC to normal control]
During the return control from the belt slip control to the normal control, the torque limit control is performed as described above, and the speed change ratio is set to the normal shift speed while the change speed of the input torque to the belt type continuously variable transmission mechanism 4 is suppressed. If it is changed, the reduction of the input torque due to the change of the rotational inertia appears remarkably, and an unnecessary deceleration feeling (pull shock) is given to the driver. For this reason, the change speed of the gear ratio is limited in accordance with the change speed of the input torque to the belt type continuously variable transmission mechanism 4.

  That is, when the BSC continuation is stopped and the return control to the normal control is started, the flow of going from step S541 → step S542 → step S543 → step S544 → step S545 in the flowchart shown in FIG. 11 is repeated until the shift is completed. That is, in step S541, the target inertia torque is calculated from the engine torque. In the next step S542, the target primary rotation change rate is calculated by the target inertia torque. Then, an inertia torque to be reduced is set, and based on this limited target inertia torque, a limited target primary rotation speed that does not exceed the rate of change (gradient) of the target primary rotation speed without limitation is calculated in step S543. . In step S544, shift control is performed based on the limited target primary rotation speed. As described above, when the speed change control based on the limited target primary rotation speed is performed, the target speed ratio characteristic with control is compared with the target speed ratio characteristic without restriction when the target speed ratio to be finally generated is compared. The change gradient of the target gear ratio is gentle.

  The return control action by the torque delay and the primary rotation increase rate limiter employed in the first embodiment will be described based on the time chart shown in FIG.

  First, engine torque characteristics will be described. The engine torque characteristics in the region from the end of the BSC to the normal return indicate that the driver request torque shows a stepwise increase characteristic, and the engine torque characteristics based on the actual torque response at the normal time when the torque limit control is not performed is the torque immediately after the BSC ends. Shows the characteristics of rising. On the other hand, as shown in the actual torque response after torque reduction by the BSC, the engine torque characteristic in the first embodiment maintains the torque for a while from the end of the BSC, and then the torque rises with a delay. Show.

  Next, the target gear ratio characteristic and the inertia torque characteristic will be described. The target primary rotational speed characteristic in the region from the end of BSC to the normal return is the target primary rotational speed characteristic at the normal time when the ultimate target characteristic is given by the step characteristic at the end of BSC and the limit control of the primary rotational speed increase is not performed. The target primary rotational speed rises with a large gradient immediately after the end of BSC. On the other hand, the target primary rotational speed characteristic according to the first embodiment shows a characteristic that the target primary rotational speed gradually rises with a gentler slope than that in the normal state. In addition, the inertia torque characteristic at the normal time sharply decreases from the BSC end time, whereas the inertia torque characteristic of the first embodiment gradually decreases from the BSC end time to the normal return time.

  Finally, drive shaft torque characteristics and inertia torque characteristics will be described. As shown in the E characteristic of FIG. 14, the drive shaft torque characteristics when both the torque delay and the primary speed increase rate limit control are not performed (normal time) have a large peak of inertia torque, but the response of the engine torque is also fast. For this reason, after the start of the shift, the torque decreases somewhat before the start of the shift, and then the torque increases. If such drive shaft torque characteristics are obtained, a shock due to gear shifting does not occur.

  Although the torque delay is performed, the drive shaft torque characteristic when the primary rotation increase rate limit control is not performed is the inertia torque characteristic that is not different from the normal time as shown in the D characteristic of FIG. As a result, the torque has a characteristic that has a drop d that the torque is significantly reduced after the start of the shift and before the start of the shift, and then the torque is increased. When such a change in the drive shaft torque occurs, the driver feels a shock and leads to deterioration in drivability and comfort.

  On the other hand, the drive shaft torque characteristic of the first embodiment that performs both the torque delay and the primary rotation increase rate limit control is the primary rotation even if the engine torque input is delayed by the torque delay, as shown in the F characteristic of FIG. Since the peak of the inertia torque can be reduced by the increase rate limit control, the torque decreases slightly after the start of the shift and before the start of the shift, and then the torque increases. That is, it can be seen that the shock can be suppressed by simultaneously performing the torque delay and the primary rotation increase rate limit control.

  As described above, when the torque slip control is performed during the return control from the belt slip control to the normal control, the control that limits the change rate of the primary rotation is performed, so that the rotation inertia at the start of the shift is performed. By reducing the change, it is possible to suppress the drive shaft torque from being lowered than before the start of the shift, and as a result, it is possible to prevent an unnecessary shock (deceleration feeling) given to the driver.

Next, the effect will be described.
In the control device and the control method for the belt type continuously variable transmission mechanism 4 according to the first embodiment, the following effects can be obtained.

(1) a primary pulley 42 that is input from a driving source (engine 1), a secondary pulley 43 that is output to driving wheels 6 and 6, and a belt 44 that spans the primary pulley 42 and the secondary pulley 43. A belt-type continuously variable stepping machine comprising secondary hydraulic control means (secondary hydraulic control unit 92) for determining a command secondary hydraulic pressure by feedback control based on a deviation between the target secondary hydraulic pressure and the actual secondary hydraulic pressure and controlling the secondary hydraulic pressure to the secondary pulley 43 In the control device of the transmission mechanism 4, the belt slip state is estimated by monitoring the phase difference θ between the vibration component included in the actual secondary hydraulic pressure and the vibration component included in the actual gear ratio, and a predetermined belt is determined based on this estimation. A belt sleeve that performs control to reduce the actual secondary hydraulic pressure so as to maintain a slip state. The loop control means (8) provided, the secondary hydraulic pressure control means, during the belt slip control, stop secondary hydraulic pressure feedback control, to control the secondary hydraulic pressure by open control.
Therefore, it is possible to provide a control device for the belt-type continuously variable transmission mechanism 4 that improves the control stability of the secondary hydraulic pressure while ensuring the estimation accuracy of the belt slip state during the belt slip control.

(2) The belt slip control means (FIG. 8) applies a vibration having an appropriate frequency and amplitude to the secondary hydraulic pressure during the belt slip control, and a vibration component included in the actual secondary hydraulic pressure and a vibration component included in the actual gear ratio. The belt slip state is estimated by monitoring the phase difference between and.
For this reason, even if the actual secondary hydraulic pressure is vibrated, the secondary hydraulic pressure control is not affected, so that the phase difference θ of the vibration component can be clearly obtained. The area can be reliably determined.

(3) The secondary hydraulic control means (secondary hydraulic control unit 92) sets the deviation only to zero during belt slip control, holds the feedback control amount until immediately before shifting to belt slip control, and holds the constant feedback control. The secondary hydraulic open control is performed using the amount.
For this reason, when returning from the open control to the feedback control, it is possible to prevent the passenger from feeling uncomfortable due to a drop in the secondary hydraulic pressure.

(4) In the control method of the belt-type continuously variable transmission mechanism 4 that performs belt slip control for controlling the belt slip state between the primary pulley 42 and the secondary pulley 43 and the belt 44 by hydraulic pressure, the belt slip control is performed by using the hydraulic pressure. The hydraulic pressure is controlled based on the multiplication value of the vibration component included in the actual hydraulic pressure and the vibration component included in the actual gear ratio, the feedback control of the hydraulic pressure is stopped during the belt slip control, and the open control is performed. To control the hydraulic pressure.
Therefore, it is possible to provide a control method for the belt-type continuously variable transmission mechanism 4 that improves the control stability of the secondary hydraulic pressure while ensuring the estimation accuracy of the belt slip state during the belt slip control.

(5) The belt slip control estimates a belt slip state by monitoring a phase difference calculated based on the multiplication value, and controls the hydraulic pressure so as to maintain a predetermined belt slip state based on the estimation.
For this reason, since the change in the belt slip state can be accurately grasped by monitoring the phase difference correlated with the belt slip state, the predetermined belt slip state can be stably maintained during the belt slip control. As a result, the target energy saving effect (practical fuel consumption effect) can be realized by belt slip control in which the belt friction reduction state is stably maintained.

  As mentioned above, although the control apparatus and control method of the belt type continuously variable transmission of the present invention have been described based on the first embodiment, the specific configuration is not limited to the first embodiment, and Modifications and additions of the design are permitted without departing from the spirit of the invention according to the claims.

  In the first embodiment, the shift hydraulic pressure control unit 7 has an example having a hydraulic circuit by step motor control in a single pressure regulation system. However, the present invention can also be applied to other single pressure regulation type or both pressure regulation type transmission hydraulic pressure control units.

  In Example 1, the example which vibrates only a secondary hydraulic pressure was shown. However, for example, in the case of a linear motion control method, the secondary hydraulic pressure and the primary hydraulic pressure may be simultaneously excited in the same phase. Moreover, it is good also as an example which excites a primary hydraulic pressure with the same phase with a secondary hydraulic pressure by oscillating line pressure.

  In the first embodiment, an example in which an appropriate vibration component is given to the instruction secondary hydraulic pressure as the means for vibrating is shown, but an example in which an appropriate vibration component is given to the solenoid current value may be used.

  In the first embodiment, as an example of the torque limit control in the return control, the input torque at the end of the belt slip control is held for a predetermined time. However, for example, a slight torque increase may be allowed as torque limit control.

  In the first embodiment, an example is shown in which the rate of change in the target primary rotation speed is limited as the limit control of the speed change rate in the return control. However, the speed ratio change rate limiting control may be an example in which a speed time constant is limited, an example in which the speed ratio at the end of belt slip control is held for a predetermined time, or an example in which these methods are combined.

  In the first embodiment, an example of application to an engine vehicle equipped with a belt-type continuously variable transmission is shown. However, the present invention is applied to a hybrid vehicle equipped with a belt-type continuously variable transmission or an electric vehicle equipped with a belt-type continuously variable transmission. It can also be applied to. In short, the present invention can be applied to any vehicle equipped with a belt type continuously variable transmission that performs hydraulic shift control.

DESCRIPTION OF SYMBOLS 1 Engine 2 Torque converter 3 Forward / reverse switching mechanism 4 Belt type continuously variable transmission mechanism 40 Transmission input shaft 41 Transmission output shaft 42 Primary pulley 43 Secondary pulley 44 Belt 45 Primary hydraulic chamber 46 Secondary hydraulic chamber 5 Final deceleration mechanisms 6 and 6 Drive wheel 7 Speed change hydraulic control unit 70 Oil pump 71 Regulator valve 72 Line pressure solenoid 73 Speed change control valve 74 Pressure reducing valve 75 Secondary hydraulic solenoid 76 Servo link 77 Speed change command valve 78 Step motor 8 CVT control unit 80 Primary rotation sensor 81 Secondary rotation sensor 82 Secondary oil pressure sensor 83 Oil temperature sensor 84 Inhibitor switch 85 Brake switch 86 Accelerator opening sensor 87 Other sensors and switches 88 Engine control unit 90 Basic Hydraulic pressure calculation section 91 Line pressure control section 92 Secondary hydraulic pressure control section (secondary hydraulic pressure control means)
93 Sinusoidal vibration control unit 94 Secondary hydraulic pressure correction unit

Claims (3)

A primary pulley that is input from a drive source, a secondary pulley that is output to a drive wheel, and a belt that spans between the primary pulley and the secondary pulley, and a belt clamping force based on a command secondary hydraulic pressure to the secondary pulley In the control device of the belt type continuously variable transmission for controlling
Based on the belt slip control permission condition, it is determined whether to permit belt slip control that reduces the secondary hydraulic pressure compared to normal control, and means for switching between the normal control and the belt slip control;
During the normal control, the command secondary hydraulic pressure is determined by feedback control based on a deviation between the target secondary hydraulic pressure and the actual secondary hydraulic pressure, the secondary hydraulic pressure to the secondary pulley is controlled, and during the belt slip control, feedback based on the deviation is performed. The belt is slipped by prohibiting the control and oscillating the secondary hydraulic pressure instead of the prohibited feedback control and monitoring the phase difference between the vibration component included in the actual secondary hydraulic pressure and the vibration component included in the actual gear ratio. A command secondary hydraulic pressure is determined so as to maintain a predetermined belt slip state based on the estimation, and a means for controlling the secondary hydraulic pressure to the secondary pulley;
A control device for a belt type continuously variable transmission. In the control method of the belt type continuously variable transmission that hydraulically controls the belt clamping force between the primary pulley and the secondary pulley and the belt,
Based on the belt slip control permission condition, it is determined whether to allow belt slip control to reduce the hydraulic pressure compared to normal control, and the normal control and the belt slip control are switched.
During the normal control, the command hydraulic pressure is determined by feedback control based on the deviation between the target hydraulic pressure and the actual hydraulic pressure to control the belt clamping force,
At the time of the belt slip control, the feedback control based on the deviation is prohibited, and instead of the prohibited feedback control , the hydraulic pressure is vibrated so that the vibration component included in the actual hydraulic pressure and the vibration component included in the actual gear ratio are A control method for a belt-type continuously variable transmission, characterized in that a command hydraulic pressure is determined based on a multiplication value to control a belt clamping force. In the control method of the belt type continuously variable transmission that hydraulically controls the belt clamping force between the primary pulley and the secondary pulley and the belt,
Based on the belt slip control permission condition, it is determined whether to allow belt slip control to reduce the hydraulic pressure compared to normal control, and the normal control and the belt slip control are switched.
During the normal control, the command hydraulic pressure is determined by feedback control based on the deviation between the target hydraulic pressure and the actual hydraulic pressure to control the belt clamping force,
At the time of the belt slip control, the feedback control based on the deviation is prohibited, and instead of the prohibited feedback control , the hydraulic pressure is vibrated so that the vibration component included in the actual hydraulic pressure and the vibration component included in the actual gear ratio are A control method for a belt-type continuously variable transmission, wherein a command hydraulic pressure is determined based on a phase difference to control a belt clamping force.

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