JP2699328B2 - Gear ratio control method of belt type continuously variable transmission for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial applications   The present invention relates to a speed ratio control method for a continuously variable transmission for a vehicle.
Things. Conventional technology   Input and output axes and their input and output axes
Input side variable pulleys with variable effective diameters
Output variable pulley, input variable pulley and
Transmission belt wound around the V-groove of the output and variable pulley
And V of the input-side variable pulley to change the gear ratio.
Supply hydraulic oil to the hydraulic cylinder that changes the groove width, or
By shifting the hydraulic oil from the hydraulic cylinder,
Shift direction switching valve device for switching the direction and hydraulic cylinder thereof
Shift by changing the supply flow rate or discharge flow rate of hydraulic oil
For a vehicle having a shift speed switching valve device for switching speed
A belt-type continuously variable transmission is known. And like this
For example, in a belt type continuously variable transmission for a vehicle,
As described in No. 60-70614, the required output is
Gin determined to occur on the minimum fuel efficiency curve
The target rotation speed and the actual rotation speed of the input shaft of the
The shift direction switching valve device is switched to
The fuel consumption efficiency of the vehicle is improved. And the vehicle stops
When the V-groove width of the input side variable pulley is large and
The gear shifting is performed so that the V-groove width of the force shaft-side variable pulley is reduced.
The directional control valve device is controlled, and the speed ratio of the continuously variable
It is common to change to the maximum value in preparation for both restarts
It is. Problems to be solved by the invention   However, in such a conventional control method, the vehicle
Gear ratio reaches the maximum value during sudden braking
The transmission of the continuously variable transmission may stop before the operation. Soshi
Requires driving force when the vehicle restarts
As the continuously variable transmission is turned again,
The gear ratio of the continuously variable transmission changes toward its maximum value.
In such a case, the transmission belt slips
There was an inconvenience. That is, when the vehicle starts, the transmission bell
Relatively large power is transmitted through the
When the transmission belt has a size corresponding to the transmission torque
Despite the need for tension, the gear ratio of the continuously variable transmission
The V-groove width of the input side variable pulley has been expanded to maximize
The transmission belt is insufficiently tensioned, causing slippage.
Because Means to solve the problem   The present invention has been made in view of the above circumstances.
The gist is that the input and output shafts,
The effective diameter provided for each of these input and output shafts
A variable input pulley and variable output pulley,
V-groove of those input side variable pulley and output side variable pulley
To change the gear ratio and the transmission belt wound around
Hydraulic cylinder for changing the V groove width of the input side variable pulley
Supply hydraulic oil to the
Change gear direction by changing gear direction by discharging
The valve changing device and the supply flow rate or
Is the shift speed that switches the shift speed by switching the discharge flow rate
Belt type continuously variable transmission for vehicles having switching valve device
When the vehicle stops, the gear ratio increases toward the maximum value.
Controls the shift direction switching valve device so that it changes quickly
Speed ratio control method in which the vehicle speed is less than a predetermined value.
If the gear ratio is too low, the hydraulic
Of hydraulic oil from the cylinder or operation to the hydraulic cylinder
Oil supply is suppressed so that the gear ratio changes slowly.
In this case, the shift speed switching valve is switched. Action and effect of the invention   In this way, when the vehicle speed is lower than a predetermined value,
Works from a hydraulic cylinder to change the gear ratio.
Suppress discharge of hydraulic oil or supply of hydraulic oil to the hydraulic cylinder
The shift speed switching valve is switched to control
When the vehicle speed is low, the change in the gear ratio of the continuously variable transmission is suppressed.
Is done. Therefore, when the vehicle restarts after sudden braking,
If the gear ratio of the continuously variable transmission changes toward the maximum value
The change is suppressed even if it
Of the transmission belt has been eliminated,
It is properly prevented. Example   Hereinafter, an application example of the present invention will be described in detail with reference to the drawings.
I do.   In FIG. 2, the power of the engine 8 is supplied by the fluid coupling 10 and the base.
Automatic transmission (hereinafter referred to as CVT) 12 and auxiliary transmission 1
4, drive shaft 20 via intermediate gear device 16 and differential device 18
To the drive wheels (not shown) connected to the
ing.   The fluid coupling 10 is connected to the crankshaft 22 of the engine 8.
Pump 24 and the pump 2 fixed to the input shaft 26 of the CVT 12
Turbine 28, which is rotated by oil from
The lock-up clamp fixed to the input shaft 26 via the damper 30
Switch 32. Lock-up clutch 32
For example, vehicle speed or engine speed or turbine 28
Is activated when the rotation speed of the
The link shaft 22 and the input shaft 26 are directly connected.   The CVT 12 is provided on the input shaft 26 and the output shaft 34, respectively.
Input side variable pulley 36 and output side variable pulley 38,
The conductive belt wound between the variable pulleys 36 and 38
With the default 40. Input variable pulley 36 and output
The side variable pulley 38 is fixed to the input shaft 26 and the output shaft 34.
Fixed rotating bodies 42 and 44, the input shaft 26 and the output shaft 34
Each can move in the axial direction and cannot rotate relative to each other.
Movable rotating bodies 46 and 48 are provided.
Body 46 and 48 are moved by hydraulic cylinders 50 and 52
The V-groove width, that is, the hook of the conductive belt 40
The diameter (effective diameter) is changed and the gear ratio γ (= input
Rotation speed N of shaft 26_in/ Rotation speed N of output shaft 34_out) Changed
It is supposed to be. Hydraulic cylinder 50 is exclusively gear ratio
actuated to change γ, hydraulic cylinder 52
Minimum clamping pressure within the range that does not cause slippage of the conduction belt 40
Is actuated to obtain The oil pump
54 constitutes a hydraulic source of a hydraulic control device described later.
And a connecting shaft (not shown) vertically passing through the input shaft 26.
Connected to the crankshaft 22 and constantly rotated by the engine.
You.   The auxiliary transmission 14 is provided coaxially with the output shaft 34 of the CVT 12.
And includes a Ravigneaux-type compound planetary gear set.
This planetary gear device includes a pair of first sun gears 56 and a second sun gear 56.
The first planetary gear meshing with the sun gear 58 and the first sun gear 56
60 and the first planetary gear 60 and the second sun gear 58
A second planetary gear 62 that fits and a ring that meshes with the first planetary gear 60
Gear 64 and the first and second planetary gears 60 and 62
And a carrier 66 rotatably supported. 2nd sun
The gear 58 is fixed to a shaft 68 integrally connected to the output shaft 34.
The carrier 66 is fixed to the output gear 70. high speed
The step clutch 72 establishes engagement between the shaft 68 and the first sun gear 56.
The low-speed brake 74 is controlled by the housing of the first sun gear 56.
The reverse brake 76 controls the engagement with the ring.
The engagement of the gear 64 with the housing is controlled. Fig. 3
Operating state and range of each friction engagement element of sub-transmission 14
At the speed reduction ratio. In FIG. 3, the mark ○
The engaged state, the x mark indicates the released state, and ρ1 and ρ2
This is the gear ratio defined from the equation. ρ1 = Z_s1/ Z_r ρ2 = Z_s2/ Z_r   Where Z_s1Is the number of teeth of the first sun gear 56, Z_s2Is the second sangi
A 58 teeth, Z_rIs the number of teeth of the ring gear 64.   Therefore, at the low speed stage in the L and D ranges,
The low speed brake 74 is actuated and the first sun gear 56
Power is transmitted at the reduction ratio (1 + ρ1 / ρ2) because it is fixed.
At high speed stages in the L and D ranges.
The entire planetary gear unit is integrated by the operation of the speed gear clutch 72.
As a result, power is transmitted at a reduction ratio of 1.
It is. In the R range, the reverse brake 76 operates.
Since the ring gear 64 is fixed to the housing,
Power is transmitted by the reverse rotation of (1-1 / ρ2).   Returning to FIG. 2, the output gear 70 of the auxiliary transmission 14 is an intermediate gear.
The engine is connected to the differential 18 through the device 16.
8 is transmitted to the left and right drive shafts 20 in the differential device 18.
After being distributed, it is transmitted to the left and right drive wheels.   FIGS. 4, 5, and 6 show the vehicle motions shown in FIG.
Shows a hydraulic control circuit for controlling the force transmission device
You. The oil pump 54 is returned to the oil tank (not shown).
Hydraulic fluid through the strainer 80
Pump to 82. The throttle valve opening detection valve 84 is
Torle valve opening θ_thThrottle pressure P corresponding to_thThe output
Occurs on port 86. Spool 88 of throttle valve 84
Is a slot that rotates with a throttle valve (not shown)
Throttle valve opening θ from Lucam 90_thGrows with
Acting force and feedback pressure from control port 92
Throttle pressure P_thTo the line oil passage 82
And the opening and closing of the output port 86. Manual valve
94 is the shift lever L (low), D (drive), N
(Neutral), R (reverse), and P (parky)
Positioning) in the axial direction in connection with the range operation,
When the first line pressure P1 of the line oil passage 82 is in the R range,
To port 96, to L for range 98, to D range
Leads to ports 98 and 100, respectively. Relief valve 102
Means that the first line pressure P1 of the line oil passage 82 is equal to or higher than a predetermined value.
When it comes to the safety valve to release the oil in line oil passage 82
Has functions.   The secondary hydraulic passage 104 is connected to the orifice 106 and the primary
Port 110 for discharging excess oil from the
Connected to the line pressure oil passage 82 via
The hydraulic valve 112 is connected to the secondary hydraulic oil via the orifice 114.
A control room 116 connected to the road 104,
In connection with the hydraulic pressure and the load of the spring 118, the secondary hydraulic
The connection with the port 120 is controlled, and the secondary hydraulic pressure of the secondary hydraulic oil passage 104 is controlled.
Maintain Pz at a predetermined value. Lube oil passage 122 has port 120
Or through the orifice 124 to the secondary hydraulic oil passage 104
ing. The lock-up control valve 126 is connected to the secondary hydraulic passage 104
The engagement side of the lock-up clutch 32 in the fluid coupling 10 and
Selectively connect to the release side. Solenoid valve 128 locks up
Controlling the opening and closing of the control chamber 130 and the drain 132 of the control valve 126,
Lock-up when solenoid valve 128 is off (de-energized)
Secondary hydraulic pressure P from secondary hydraulic oil passage 104 to the release side of clutch 32
z is transmitted and power is transmitted via the fluid coupling 10.
However, when solenoid valve 128 is on (excited), it is locked.
Connect to the engagement side of the up clutch 32 and the oil cooler 134
The secondary hydraulic pressure Pz is supplied from the secondary hydraulic oil passage 104,
The power is transmitted through the backup clutch 32. Cooler
Ipass 136 controls the cooler pressure.   The gear ratio control device includes a first spool valve 142 and a first
A shift direction switching valve device 138 comprising a magnetic valve 144;
Speed switching valve device comprising a valve 146 and a second solenoid valve 148
Device 140 is provided. During the period when the first solenoid valve 144 is off
The spool of the first spool valve 142 is controlled by the secondary hydraulic pressure Pz of the chamber 150.
The first spring of the port 154.
The in-pressure P1 is supplied via the port 156 of the first spool valve 142.
It is sent to the port 158 of the second spool valve 146,
The connection with the drain 162 has been disconnected. This allows the gear ratio
γ is switched in the decreasing direction. First solenoid valve 144 is on
During the period, the hydraulic pressure of the chamber 150 is changed to the drain 164 of the first solenoid valve 144.
And the spool of the first spool valve 142
Pressed toward chamber 150 by spring 152, port 156 has a first
Line P1 does not occur, and port 160 is connected to drain 62.
Continued. This allows the gear ratio to be switched in the increasing direction
You.   While the second solenoid valve 148 is off, the second spool valve 146
Is pushed toward the spring 168 by the secondary hydraulic pressure Pz in the chamber 166.
Port 158 and port 170 are disconnected,
Port 172 is connected to port 174. Ports 170 and 172 are
Connected to the input side hydraulic cylinder 50 of CVT12 via oil passage 176
Have been. While the second solenoid valve 148 is ON, the oil in the chamber 166 is
Pressure is discharged from the drain 178 of the second solenoid valve 148,
The spool of the valve 146 is pressed toward the chamber 166 by the spring 168
Port 158 is connected to port 170 and port 172
The connection to port 174 is broken. Port 174 has oil passage 180
It is connected to port 160 via. Orifice 182 is
2 When the solenoid valve 148 is off, pour a small amount of oil
To the 170. Therefore, whether the first solenoid valve 144 is off
While the second solenoid valve 148 is on, the input side hydraulic pressure of CVT12
Oil is quickly supplied to the cylinder 50, and the gear ratio γ
It gets smaller quickly. The first solenoid valve 144 is off and the second solenoid
While the valve 148 is off, the input side hydraulic cylinder 50 of CVT12
Oil is supplied to orifice 182 via CVT
The gear ratio γ of 12 gradually decreases. The first solenoid valve 144
If the second solenoid valve 148 is on and the second solenoid valve 148 is on,
Oil is supplied to and discharged from the power-side hydraulic cylinder 50.
Speed ratio γ of CVT12
Therefore, it increases slowly. The first solenoid valve 144 is on and
While the second solenoid valve 148 is off, the input side hydraulic cylinder 5
0 is discharged from the drain 162, so the CVT12
The speed ratio γ increases rapidly.   The gear ratio detection valve 184 is shown in detail in FIG. S
Leaves 186 and 188 are coaxially arranged in bore 190 and
It is fixed in the axial direction by a coupling 192. Stick 194
Penetrates the end of the sleeve 186, and the spring seat 196 is fixed to the tip.
Is defined. The other bar 198 fixed to one end of the bar 194,
Sliding contact with the movable rotary body 46 on the input side, the rod 194 is rotated
Amount of displacement equal to the amount of displacement of body 46 in the axial direction
Move. The spool 200 has lands 202 and 204,
It is fitted in the sleeve 188 so as to be movable in the axial direction.
The land 202 has a space 206 between the lands 202 and 204 in an oil chamber 208.
The land 204 has a passage 210 communicating with the
The opening area of the port 212 of the sleeve 188 is controlled. port
212 connects to the drain 214 through the space around the sleeve 186
Has been continued. The oil chamber 208 has an output for generating the speed ratio pressure Pγ.
Port 216, output port 216 is through orifice 218
And is connected to a line oil passage 82. Spring 220 is a spring support
Three bars 194 are provided between the sleeves 196 and 188.
The spring 222 is urged in the direction of pushing out from the spring 186, and the spring 222 is
6 and the flange 224 of the spool 200.
Urges the cylinder 200 toward the oil chamber 208.   Therefore, the CVT 12 with respect to the fixed rotating body 42 on the input side is
The gear ratio γ increases as the displacement amount of the movable rotating body 46 increases.
Great. The rod 194 slides due to the increase in the displacement of the movable rotating body 46.
As it is pushed out of the leave 186, the spring in the direction of the oil chamber 208
The biasing force on the spool 200 by 222 is reduced. This result
As a result, the spool 200 moves toward the rod 194, and the land 204
The opening area of the port 212 is increased to increase the oil discharge flow rate.
Therefore, the speed ratio pressure Pγ of the output port 216 decreases.
You. The transmission ratio pressure Pγ is the hydraulic medium supplied to the output port 216.
It is produced by controlling the amount of body excretion,
An upper limit is defined for the first line pressure P1. Fig. 8 and
9 and the dashed line in FIG. 9 indicate two ratios of the speed ratio pressure Pγ and the speed ratio γ.
The relationship is illustrated. The first line pressure as described below
P1 decreases as the gear ratio γ decreases.
A gear ratio γ at which Pγ becomes equal to the line pressure P1 (this gear ratio
The ratio γ is the throttle pressure P_thAnd therefore the engine output torque
Lower than the transmission ratio range).
In the frame, Pγ = P1. 8 and 9
, The two-dot chain line is the ideal value of the first line pressure P1.
Therefore, T1> T2.   The cut-off valve 226 controls the lock-up control valve 126.
A chamber 230 communicating with the imperial chamber 130 via an oil passage 228, and
Move relative to the oil pressure in 230 and the spring force of spring 232.
Spool 234 and the solenoid valve 128 is off,
That is, when the lockup clutch 32 is in the released state.
(When shifting gears in the auxiliary transmission 14, when the power transmission system
Lock-up clutch 32 released to absorb shots
), And the transmission ratio pressure Pγ becomes the primary
The transmission to the regulator valve 108 is prevented.   Primary regulation as first line pressure generating means
Data valve 108 is throttle pressure P_thPort to which is supplied
236, port 238 to which gear ratio pressure Pγ is supplied, line oil passage
Port 240 connected to 82, suction of oil pump 54
Port 242 and orifice 244
Port 24 to which the first line pressure P1 is supplied via
6.Axial movement to connect port 240 and port 242
Control the spool 248, throttle pressure P_thReceiving sp
Spool 250 that biases port 248 toward port 238, and
Spring 252 that biases the spool 248 toward the port 238.
I have. Pressure receiving surface of two lands from under spool 248
The products are A1, A2 and throttle pressure P, respectively._thReceiving spoo
A3, the pressure receiving area of the land of A250, and the acting force of the spring 252
Is W1, the following equations (1) and (2) hold.   The cutoff valve 226 opens and the gear ratio pressure P
If γ is coming, P1 = (A3 · P_th+ W1-Al · Pγ) / (A2-A1)                                         …… (1)   The cutoff valve 226 closes and the gear ratio pressure P
If γ has not come P1 = (A3 · P_th+ W1) / (A2-A1) …… (2)   The line pressure P1 in the equations (1) and (2) is
8 and 9, a solid line and a dashed line, respectively.
Indicated by   In FIG. 6, a support as a second line pressure generating means is shown.
The primary valve 254 is connected to the first
Induction pressure P1 is derived from port 98 of manual valve 94
Input port 256, the output at which the second line pressure Pl2 is generated
Port 258, port 260 through which the gear ratio pressure Pγ is led, feed
The second line pressure Pl2 as the feedback pressure is applied to the orifice 262
Led through port 264, input port 256 and output port
Spool 266 for controlling opening and closing with
_thThe led from port 268, the slot from that port 268
Pressure P_thUrges the spool 266 toward port 260
Spool 270 and spool 266 toward port 260
It has a biasing spring 272. 2 from the bottom of the spool 266
The pressure receiving area of one land is B1, B2, throttle pressure P_thReceiving
The pressure receiving area of the land of spool 270
When the elastic force of 72 is defined as W2, the following equation (3) holds.
I do. Pl2 = (B3 · P_th+ W2-B1 · Pγ) / (B2-B1)                                         …… (3)   FIG. 10 is generated by sub-primary valve 254
It shows the relationship between the second line pressure Pl2 and its ideal value.
You.   The shift valve 274 is connected to the second line pressure P in the D and L ranges.
l2 led input port 276, output port 278,280,
Discharge ending with drain 284 with orifice 282
Port 288 connected to oil passage 286.
From the port 100 of the dual valve 94 to the first line pressure P1
Is supplied to the control port 300, other control ports 302,
304, drain 306, spool 308, and its spool 308
To the control port 304.
Secondary oil is supplied to the control ports 302 and 304 via the orifice 312.
Pressure Pz is derived. Also, the hydraulic pressure of the control ports 302 and 304
Is controlled by a solenoid valve 314. 2 from the bottom of the spool 308
The pressure receiving areas of the two lands are S1 and S2, respectively, and S1 <S2
It is. Also, the on / off of the solenoid valve 314 is controlled by the driving
Is controlled in relation to the
6 drains the oil.   When the spool 308 is located at the spring 310 side, the input port
Port 276 is connected to output port 278, and output port 280 is
Port 288. Therefore, from output port 278
Accumulator with second line pressure Pl2 having piston 318
Gear 320 and the high-speed gear clutch 72,
4 is a high speed stage.   If the spool 308 is at the position on the control port 304 side,
Output port 276 is connected to output port 280 and output port 27
8 is connected to the drain 306. Therefore, output port 28
The second line pressure Pl2 from 0 is the accumulator 32 for the low speed stage.
2 and the auxiliary transmission 14 is set to the low speed stage.   In the case of the L range, the first line pressure is connected to the control port 300.
Solenoid valve 314 is turned off because P1 is not guided
The spool 308 initially acts on the land of the pressure receiving area S2
Later, the secondary hydraulic pressure Pz acts on the land of the pressure receiving area S1.
The secondary hydraulic pressure Pz moves to the spring 310 side, but the solenoid valve 3
When 14 turns on, the hydraulic pressure at control ports 302 and 304 decreases.
Therefore, the spool 308 is ported according to the biasing force of the spring 310.
Move to 304 side. That is, in the L range, the solenoid valve 314
The high speed and low speed of the sub-transmission 142
Is switched.   In the D range, the first line pressure P1
The spool 308 once moves to the position on the spring 310 side.
Then, the land from the control port 300 to the land of the pressure receiving area S2
1 line pressure P1 acts, and the solenoid valve 314 is subsequently turned off.
Spool 308 is in the position of the spring 310 side regardless of
Will be retained. Therefore, the auxiliary transmission 14 is held at the high speed stage.
You.   The shift timing valve 324 is connected to the high-speed clutch 72.
Control port 326 that communicates with the
Spool 328 whose axial position is controlled by hydraulic pressure
High speed gear when upshifting from low gear to high gear
Of oil supply to the clutch 72 for
The amount of oil discharged from the key 74 is controlled.   FIG. 11 shows an electronic control device for controlling the operation of the above-described hydraulic control device.
The circuit is shown. The so-called My consisting of CPU, RAM, ROM, etc.
The electronic control unit 330 equipped with a microcomputer
Throttle valve opening sensor installed in the intake pipe of gin 8
340 to throttle valve opening θ_thA signal representing
You. In addition, the output gear 34 of the CVT 12 or the output gear of the
The vehicle speed is detected from the vehicle speed sensor
The signal representing V is input from the input shaft rotation sensor 344 to the CVT12.
Rotation speed N of shaft 26_inIs output from the temperature sensor 346.
Engine cooling water temperature T_wSignal indicating the shift position
A signal indicating the operating position P of the shift lever is sent from the
The child control device 330 is supplied to each of them. Electronic control unit 330
CPU in the ROM uses the temporary storage function of the RAM while
Process the input signal according to the remembered program and operate the solenoid valve
Signals for driving 128, 144, 148, 314 are amplified by the amplifying device 33.
Output via 2 respectively.   In the electronic control unit 330, first, the steps shown in FIG.
The control mode is selected by executing the step. You
That is, step SM1 is executed to initialize the electronic control unit.
When the conversion is executed, step SM2 is executed and each sensor is
Input signals from the
According to the signal conditions
System, step SM4 mutual control with institutional computer
Control, lock-up control of step SM5, change of step SM6
Speed control is performed sequentially or selectively. Step SM
In the diagnosis of 3, the engine 8 and CVT12 etc. work normally.
It is for diagnosing whether or not it is moving. Step
Mutual control with the engine computer of the SM4 engine
8 for controlling the ignition timing and fuel injection amount
It controls the interaction with the computer. Stay
The lock-up control of the SM5
Valve opening θ_thFrom the relationship determined in advance based on
For controlling the solenoid valve 128 for operating the up clutch 32
It is for Note that the above relationship is
Rotational speed of bin 28 and throttle valve opening θ_THAsk from
It is also possible. The gear change control in step SM6 is
Shift lever position P, vehicle speed V, throttle valve opening θ_thBased on
In step SM7, the sub-transmission switching control is performed.
It is also used to judge whether to use the CVT shift control of the Step SM8
It is. The switching control of the subtransmission in step SM7
Speed of the auxiliary transmission 14 based on the position P, the vehicle speed V, etc.
Electromagnetic that selectively switches to gear, low gear, or reverse
This is for controlling the valve 314. And step S
The control value is output in M9.   In the shift control of the CVT in step SM8, FIG.
Steps with the functions shown in the control function block diagram of
Is to be executed. That is, the rotation of the input shaft 26
The input shaft rotation sensor 344 that detects the rotation speed rotates the input shaft 26
Rolling speed N_inIs supplied to the deviation calculating means 358. Throttle valve
The opening sensor 340 detects the throttle valve opening θ._thDetect and target
Provided to the rotation speed determining means 354 and the switching reference value setting means 356
Pay. The target rotation speed determining means 354 is a throttle valve opening.
θ_thThe required output represented by is generated on the minimum fuel efficiency curve of the engine.
Throttle valve opening based on the relationship determined in advance to produce
θ_thCVT1 based on the vehicle speed V and the range of the auxiliary transmission 14.
Target rotation speed N of input shaft 26 of 2_in ⁰Determine the deviation calculator
Feed to stage 358. The deviation calculating means 358 calculates the target rotation speed N_in ⁰
And the actual rotation speed N of the input shaft 26_inDeviation from Δn_in(= N_in ⁰
−N_in) Is calculated and supplied to the solenoid valve control means 360. one
On the other hand, the switching reference value setting means 356 controls the solenoid valves 144 and 148
Reference value n for switching₁To n₈The relationship that was determined in advance
To throttle valve opening θ_thDetermined based on the
Supply to control means 360. Here, each reference value is n₁> N_Three> N
_Two> N_Five> N_Four> N₇> N₆> N₈And also n₁, N_Three, N_Two, N_FiveIs
Positive value, n_Four, N₇, N₆, N₈Is a negative value. The switching group
Reference value n₁To n₈May be a constant value.   The solenoid valve control means 360 determines the actual vehicle speed V in advance.
Constant value V₀Judge whether₀If less than the first
Set the solenoid valve 144 and the second solenoid valve 148 to the excited (on) state.
Control the speed of change of the gear ratio γ of CVT12,₀Below
If there is no running speed, that is, if
Conversion reference value n₁To n₈And deviation Δn_inAnd the first electromagnetic
Solenoid SOL1 for valve 144 and solenoid for second solenoid valve 148
A drive signal for exciting the drive SOL2 is output. This electromagnetic
The control operation corresponding to the function of the valve control means 360 is shown in FIG.
Indicated by a row chart. That is, step SS
At 1 the actual vehicle speed V is a predetermined constant value V₀Less than
It is determined whether it is below or not, and if this determination is affirmed,
Step SS2 is executed and the first solenoid valve 144 and the second solenoid valve
148 are both energized, but if denied,
The CVT shift control subroutine of step SS3 is executed. This
CVT shift control subroutine is executed as shown in Fig. 14.
As a result, as shown in FIG.
Is the deviation Δn_inIs controlled in the direction in which
Change rate of deviation Δn_inIs controlled in relation to Also,
Gear ratio control during sudden braking (not shown) during sudden braking of the vehicle
CVT12 changes due to rapid downshift by routine
The speed ratio γ is its maximum value γ_maxCan be changed to
ing. FIG. 16 shows each content of the flag F in FIG.
FIG. Also, the predetermined constant value V₀Is
The vehicle restarts when the gear ratio γ is not at its maximum value.
When the shift control subroutine shown in FIG.
Also, a value at which the transmission belt 40 does not slip, for example,
Deviation Δn_inIs n_TwoSmaller than the
Vehicle speed or deviation Δn_inIs n_FiveOr n_Fourthan
The vehicle speed is selected to be smaller and slower upshift
You. Such a vehicle speed is normally collected by a vehicle speed sensor 342.
This is a minimum possible value, for example, a value of about 3 km / h.   As described above, according to this application example, as described above, the vehicle speed V
Is a predetermined constant value V₀When the following, the first solenoid valve
144 and 148 are both on and CVT12 is slow
The vehicle shifts to the shift state, and the CV
Before the transmission ratio γ of T12 reaches its maximum value, the rotation of CVT12
Is stopped, the vehicle speed V does not increase when the vehicle restarts.
Constant value V₀The rapid change of the gear ratio γ is suppressed until
Of the transmission belt 40 and the resulting durability
The reduction of noise and the generation of noise are eliminated.   That is, as an example, in the timing chart of FIG.
As shown, when a sudden braking operation of the vehicle is performed, it is not shown.
Rapid downshift by the gear ratio control routine during sudden braking
And the speed ratio γ is rapidly increased. This state
When the CVT 12 is rotating, the hydraulic cylinder 5
Hydraulic oil in 0 is the second spool valve 146 and the first spool valve
Despite being discharged to drain through 142,
Is moving (movable rotating body 46 is moving)
Hydraulic pressure P in the input side hydraulic cylinder 50₁Is generated
You. That is, the hydraulic pressure Pc in the hydraulic cylinder 50 becomes P₁Becomes   For normal braking, the vehicle must follow the broken line in FIGS. 18 and 20.
Speed decreases and gear ratio becomes γ_maxIt stops after that, but suddenly
Since braking reduces the vehicle speed along the dashed line,
When the rotation of the wheels stops before the speed ratio γ reaches the maximum value
There is a case. In this application example, even in such a case,
As shown at point A, the vehicle speed V is determined before the wheels stop.
Constant value V₀It is determined that
The second solenoid valve 148, which was off until then, is turned on.
This is changed to a slow downshift state. For this reason,
Even if the wheels stop and the rotation of CVT12 stops, oil
The discharge of hydraulic oil from the pressure cylinder 50 is suppressed.
Therefore, the hydraulic pressure Pc in the hydraulic cylinder 50 does not decrease so much.   Therefore, during the subsequent restart operation, the hydraulic cylinder
Since the hydraulic pressure Pc within 50 is relatively maintained, the transmission belt
Forty slips are eliminated. With the restart of the vehicle
The vehicle speed V is the constant value V₀Exceeds the point B shown in FIG.
As a result, the second solenoid valve 148 is turned off,
And the speed ratio γ is increased. this
When the gear ratio γ reaches the maximum value, the input variable
Hydraulic oil in the hydraulic cylinder 50 with the V groove width of the
The pressure becomes approximately atmospheric pressure. Section C in FIG. 17 shows this state.
You.   The vehicle speed V is V₀Hydraulic cylinder 50 when
In the case of the conventional type that does not suppress the hydraulic oil flowing out of the
Is as shown by the one-dot chain line in FIG. That is,
The first solenoid valve 144 is on and the second solenoid valve 148 is off
Condition is maintained during sudden braking and subsequent restart operations.
The gear ratio γ of the CVT 12 is still at its maximum value γ_maxReached
If the rotation of the CVT12 stops before reaching the
The discharge of hydraulic oil from the pressure cylinder 50 causes the hydraulic cylinder
The hydraulic pressure Pc in the damper 50₁From atmospheric pressure
P close to_TwoAnd the belt tension decreases. At this time belt rotation
Since the rotation is stopped, the speed ratio γ hardly increases. did
As a result, the accelerator pedal is operated and the vehicle restarts.
Initially, as shown in FIG.
Although there is a temporary increase in hydraulic pressure due to rotation,
Hydraulic pressure Pc in hydraulic cylinder 50 is still large due to pressure generation delay
P close to atmospheric pressure_TwoAnd the tension of the transmission belt 40 is insufficient.
Power is transmitted from the engine 8
It is inevitable that the transmission belt 40 will slip.
It was. CVT12 rotation stopped due to sudden braking
Occurs not only when the vehicle stops but also when the wheels are locked.   As described above, one application example of the present invention has been described based on the drawings.
However, the present invention is applied in other aspects.   For example, in the application example described above, the vehicle speed V is a constant value V₀Less than
By having a slow downshift when
The outflow of hydraulic oil in the hydraulic cylinder 50 on the input side is suppressed.
To stop the outflow of hydraulic oil
It doesn't matter.   In addition, the input side hydraulic cylinder 50 of the application example described above is
V-groove width of input side variable pulley 36
It is configured to expand, but with the supply of hydraulic oil
It may be configured to enlarge the V groove width.
You. In such a case, the vehicle speed V becomes a constant value V₀Becomes
The supply of hydraulic oil is suppressed.   In the above application example, when the vehicle restarts, the vehicle speed V
Constant value V₀Over the input side hydraulic cylinder 50
It is configured so that the spill of hydraulic oil is restricted.
As shown in the figure, the constant value V₀Value V different from₁Even if is used
It is good. At this time, V₀, V₁Stops the CVT12 from rotating
The vehicle speed is determined to be as low as possible immediately before or at the time of stop.
By doing so, the gear ratio γ of the CVT 12 during sudden braking
Is the maximum value γ_maxAs close as possible to
You.   In the application example described above, V₀Is a constant value
However, it can be a function of other variables.   The above is merely an application example of the present invention.
Therefore, the present invention may be variously modified without departing from the spirit thereof.
Further modifications can be made.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart for explaining the main part of the operation of the apparatus to which the present invention is applied. FIG. 2 is a skeleton view showing a vehicle power transmission device to which the present invention is applied. FIG. 3 shows the second
FIG. 4 is a diagram illustrating a relationship between a range of a subtransmission and a friction engagement device in the illustrated device. FIGS. 4 to 6 are circuit diagrams showing in detail a hydraulic control apparatus for operating the apparatus shown in FIG. FIG. 7 is a sectional view showing the gear ratio detection valve of FIG. 6 in detail. FIGS. 8 and 9 are graphs showing the characteristics of the first line hydraulic pressure in FIGS. 4 to 6. FIG. Figure 10 shows the fourth
7 is a graph showing characteristics of a second line hydraulic pressure in FIGS. FIG. 11 is a block diagram showing a circuit provided in the apparatus of FIG. FIG. 12 is a flowchart for explaining the operation of the apparatus shown in FIG. FIG. 13 is a functional block diagram for explaining functions in steps of the shift control of the CVT in the flowchart of FIG. FIG. 14 is a diagram showing the speed change control subroutine of FIG. 1 in detail. FIG. 15 is a diagram for explaining the operation of the CVT in relation to the deviation. FIG. 16 is a table showing the operation of the first solenoid valve and the second solenoid valve in the operation shown in FIG. 14 by case. FIG. 17 is a time chart showing changes in vehicle speed V, gear ratio γ, oil pressure in the input side hydraulic cylinder, changes in the first solenoid valve and the second solenoid valve in relation to the operation shown in FIG. FIG. 18 is a graph showing the vehicle speed and the CVT input shaft rotation speed during braking of the vehicle in relation to the gear ratio. FIG. 19 is a diagram corresponding to FIG. 1 showing another application example of the present invention. FIG. 20 is a graph showing a relationship between a vehicle speed and a gear ratio in a braking state of the vehicle. 12: CVT (belt-type continuously variable transmission) 26: input shaft, 34: output shaft 36: input side variable pulley 38: output side variable pulley 40: transmission belt 50: hydraulic cylinder 138: shift direction switching valve device 140: shift Speed switching valve device γ: gear ratio V: vehicle speed

Claims (1)

(57) [Claims] An input shaft and an output shaft; an input variable output pulley and an output variable pulley having variable effective diameters provided on the input and output shafts, respectively; and wound around V grooves of the input variable pulley and the output variable pulley. A transmission that switches the transmission direction by supplying or discharging hydraulic oil to a hydraulic cylinder that changes the V-groove width of the input-side variable pulley in order to change the transmission ratio. In a vehicle belt-type continuously variable transmission having a direction switching valve device and a shift speed switching valve device that switches a shift speed by switching a supply flow rate or a discharge flow rate of hydraulic oil of the hydraulic cylinder, when a vehicle stops, a shift is performed. A speed ratio control method of controlling the speed change valve device so that the ratio changes quickly toward a maximum value, wherein the vehicle speed is lower than a predetermined value. When the gear ratio is changed, the speed change valve is controlled so as to suppress the discharge of the hydraulic oil from the hydraulic cylinder or supply of the hydraulic oil to the hydraulic cylinder for changing the speed ratio so that the speed ratio changes gradually. A gear ratio control method for a vehicle belt-type continuously variable transmission, characterized by switching.