JPS62180164A - Control method for vehicle transmission - Google Patents

Abstract

PURPOSE:To ensure the function of releasing the lockup clutch of a hydraulic coupling by changing the timing or releasing said clutch on the basis of the actual change gear ratio of a stepless transmission. CONSTITUTION:Through the gear change of a sub-transmission, a solenoid valve 314 is turned OFF, the actual change gear ratio gamma of a stepless transmission 12 is operated and a lockup release instruction time T3 is decided. Therefore, the decision is so made that the actual release of a lockup clutch 32 will be done properly at an optimum stage during the shift-up time of the sub- transmission 14. Engine prefiring and the like due to advancing too much the release of the lockup clutch 32 can be thereby prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of controlling a vehicle transmission.

Prior Art A continuously variable transmission in which power from an engine is transmitted through a fluid coupling with a lock-up clutch and a gear ratio is changed steplessly, and a continuously variable transmission having at least two forward gears. A vehicular transmission is known that includes a sub-transmission connected in series to a rear stage, and a lock-up clutch of the fluid coupling is released when the gear stage of the sub-transmission is changed. According to such a vehicle transmission, the speed change range of the continuously variable transmission section can be made small, and the continuously variable transmission can be made compact, and the auxiliary transmission is connected to the rear stage of the continuously variable transmission. has the characteristic of being able to transmit large driving force without increasing the input torque to the continuously variable transmission section. For example, the patent application filed earlier by the applicant in 1982-1
This is what is described in No. 44985. In this type of vehicle transmission, the gear change of the auxiliary transmission is automatically determined from a predetermined shift pattern based on the vehicle speed, throttle valve opening, etc. Generally, a lock-up clutch of a fluid coupling is opened and closed when switching.

When the auxiliary transmission is upshifted while the engine is transmitting power (power-on state or positive torque state) while the vehicle is accelerating, if the lock-up clutch is released too early, the engine When engine racing occurs, if it is too late, the gear change will be completed before the lock-up clutch is released, causing torque fluctuations due to torsional vibration in the drive system and impairing drivability. It is desirable to release the lock-up clutch within the shift time (so-called inertia phase time) from the time when the low speed gear is released to the time when the high speed gear is established.

In contrast, for example, conventional electronically controlled automatic (staged)
Similar to lock-up clutch release control in a transmission, the lock-up clutch is released by generating a signal that releases the lock-up clutch after a certain period of time has elapsed from the time when an upshift of the auxiliary transmission is determined while the engine is transmitting power. It is conceivable to release the up clutch during the shift time of the auxiliary transmission. According to this, by appropriately setting the predetermined time, it is possible to prevent the engine from revving up due to the lock-up clutch being released too early.

Problems to be Solved by the Invention However, in a transmission for a vehicle 4 in which the auxiliary transmission is connected to the rear stage of the continuously variable transmission, the amount of human power applied to the auxiliary transmission increases as the gear ratio of the continuously variable transmission changes. If the torque and the inertia torque of the rotating body located on the front side of the auxiliary transmission change and the shifting time of the auxiliary transmission changes, the gear change will be completed before the lock-up clutch is released. In some cases, this may impair drivability. In addition,
The predetermined time period from when it is determined that an upshift of the auxiliary transmission is to be performed until a signal for releasing the lock-up clutch is generated is extremely short (although it is possible to set
With such a setting, the lock-up clutch may be released too early due to variations in the shift start timing of the auxiliary transmission.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The gist is a continuously variable transmission in which engine power is transmitted through a fluid coupling with a lock-up clutch and the gear ratio is changed steplessly, and at least two forward speeds.
and a sub-transmission connected in series to the rear stage of the continuously variable transmission, the lock-up clutch of the fluid coupling being released when the gear of the sub-transmission is switched. A control method for a vehicle transmission, comprising:
The purpose of the present invention is to change the timing of opening of the lock-up clutch performed when upshifting the auxiliary transmission based on the actual gear ratio of the continuously variable transmission.

Operation and Effect of the Invention By doing this, the input torque to the auxiliary transmission changes as the gear ratio of the continuously variable transmission changes, and the torque of the rotating body located on the front side of the auxiliary transmission when changing gears is reduced. Even if the inertia torque changes and the shift time of the auxiliary transmission changes, the timing of the lock-up clutch release operation performed when upshifting the auxiliary transmission is changed based on the actual gear ratio of the continuously variable transmission. Therefore, the lock-up clutch is reliably released within the shift time of the sub-transmission.

Therefore, engine revving caused by opening the lock-up clutch too early, and torque fluctuations and deterioration in drivability caused by opening the lock-up clutch too late are suitably prevented.

Here, the timing of the lock-up clutch release operation is as follows:
Preferably, the operation is performed earlier as the gear ratio of the continuously variable transmission becomes more on the speed increasing side than on the decelerating side. In other words, it is executed early as the gear ratio of the continuously variable transmission changes from a large value to a small value. EMBODIMENT OF THE INVENTION Hereinafter, an application example of the present invention will be explained in detail based on the drawings.

In FIG. 2, the power of an engine (not shown) is transmitted through a fluid coupling 10. Belt type continuously variable transmission (hereinafter referred to as CVT) 12
．． Sub-transmission 14. The signal is transmitted via an intermediate gear device 16 and a differential gear device 18 to a drive shaft (not shown) connected to a drive shaft 20.

The fluid coupling 10 includes a pump 24 connected to the crankshaft 22 of the engine, a turbine 28 fixed to the input shaft 26 of the CVT 12 and rotated by oil from the pump 24, and fixed to the human power shaft 26 via a damper 30. A lock-up clutch 32 is provided. The lock-up clutch 32 is activated when, for example, the vehicle speed, the engine rotational speed, or the rotational speed of the turbine 28 exceeds a predetermined value, and connects the crankshaft 22 and the input shaft 26 directly.

The CVT 12 includes variable pulleys 36 and 38 provided on the human power shaft 26 and the output shaft 34, respectively, and a transmission belt 40 wound around the variable pulleys 36 and 38.
It is equipped with The variable pulleys 36 and 38 are fixed rotating bodies 42 and 44 fixed to the human power shaft 26 and the output shaft 34, respectively, and are provided to the input shaft 26 and the output shaft 34, respectively, so as to be movable in the axial direction and non-rotatable relative to the shaft. When the movable rotors 46 and 48 are moved by hydraulic cylinders 50 and 52, the v-groove width, that is, the hanging diameter (effective diameter) of the transmission belt 40 is changed, and the CVT 12 The gear ratio r (=rotational speed N of the human power shaft 26, 7/output shaft 34
The rotational speed (Nout) of the motor is changed.

The hydraulic cylinder 50 is operated exclusively to change the gear ratio γ, and the hydraulic cylinder 52 is operated exclusively to obtain the minimum clamping force within a range where the transmission bell 1-40 does not slip. Note that the oil pump 54 constitutes a hydraulic pressure source of a hydraulic control device to be described later, and is connected to the input shaft 26.
The crankshaft 22 is connected to the crankshaft 22 by a connecting shaft (not shown) that runs vertically through the engine, and is constantly driven to rotate by the engine.

The auxiliary transmission 14 is a stepped transmission that is connected in series to the rear of the CVT 12 and is automatically switched between a high gear and a low gear according to the driving conditions of the vehicle.
It is provided coaxially with the output shaft 34 of the VT 12 and includes a Ravigneau type compound planetary gear device. This planetary gear device includes a pair of first sun gear 56 and second sun gear 5.
8, a first planet gear 60 that meshes with the first sun gear 56, a second planet gear 62 that meshes with the first planet gear 60 and the second sun gear 58, a ring gear 64 that meshes with the first planet gear 60, and a first planet gear 64 that meshes with the first planet gear 60. 't1ffi gear 60 and a carrier 66 that rotatably supports the second planetary gear 62. The second sun gear 58 is fixed to a shaft 68 that is integrally connected to the output shaft 34, and the carrier 66 is fixed to an output gear 70. The high speed clutch 72 controls engagement between the lever 68 and the first sun gear 56 , the low speed brake 74 controls engagement of the first sun gear 56 with the housing, and the reverse brake 76 controls engagement between the ring gear 64 and the first sun gear 56 .
control engagement of the housing with respect to the housing. FIG. 3 shows the operating state of each friction engagement element of the sub-transmission 14 and the reduction ratio in each range. In the figure, ◯ indicates an engaged state, X indicates a released state, and ρ1 and ρ2 are gear ratios defined by the following equation.

ρ1=Z, , /Z.

ρ2=Z, □/Zr However, Zsl is the number of teeth of the first sun gear 56, and Zs□ is the number of teeth of the second sun gear 56.
The number of teeth of sun gear 58 and Zr are the number of teeth of ring gear 64.

Therefore, in the low speed gear stages in the L, S, and D ranges, the low speed brake 7 serves as the first frictional engagement device.
4 is activated and the first sun gear 56 is fixed, power is transmitted at the reduction ratio (1+ρl/ρ2).
In the high gear stages of L, S, and D ranges,
The entire planetary gear system rotates as a unit by the operation of the high-speed clutch 72 as the second frictional engagement device, thereby transmitting power at a reduction ratio of 1. Furthermore, in the R range, the ring gear 64 is fixed to the housing by the operation of the reverse brake 76, so that the dynamic saw is transmitted at the reverse rotation of the gear ratio (1-1/ρ2).

The output gear 70 of the auxiliary transmission [14] is connected to the differential gear device 18 via the intermediate gear device 16, and the power of the engine is distributed to the left and right drive shafts 20 in the differential gear device 18, respectively. is transmitted to the drive wheels.

FIG. 4 shows a hydraulic control circuit for controlling the vehicle power transmission device shown in FIG. The oil pump 54 pumps hydraulic oil and the like returned into an oil tank (not shown) through a strainer 80 to a suction line pressure oil passage 82 . The throttle valve 84 generates a throttle pressure Pl corresponding to the throttle valve opening θ at its output port 86. The spool 88 of the throttle valve 84 receives in opposite directions an acting force that increases as the throttle valve opening θ increases from a throttle cam 90 that rotates together with the throttle valve (not shown) and a throttle pressure P as a feedback pressure from the control port 92. Receptacle, line pressure oil passage 82 and output port 8
Controls opening and closing with 6.

The manual valve 94 is located on a shift lever (not shown), S (second), D (drive), N (neutral), R (reverse), and P (park).
A hydraulic actuator 76 is positioned in the axial direction in relation to range operation and operates a reverse brake 76 through a port 96 when in the R range by applying a second line pressure Pffi2 output from an output port 258 of a sub-primary valve 254 to be described later. ', to port 98 in the L range, and to ports 98 and 100 in the D range. The relief valve 102 has a function as a safety valve that releases oil in the line oil passage 82 when the first line pressure P1) in the line pressure oil passage 82 reaches a predetermined value -H.

The secondary hydraulic oil passage 104 is connected to the line pressure oil passage 82 via an orifice 106 and a port 1) 0 through which excess oil of the primary regulator valve 108 is discharged, and the secondary regulator valve 1) 2 )4
The control room 1 is connected to the secondary hydraulic fluid line 104 via
) 6, and controls the connection between the secondary hydraulic oil passage 104 and the port 120 in relation to the oil pressure of the control chamber 1) 6 and the load of the spring 1) 8 to Maintain the oil pressure Pz at a predetermined value. Lubricant oil passage 122 is connected to secondary hydraulic oil passage 104 via port 120 and orifice 124 . The lock-up control valve 126 is connected to the secondary hydraulic oil passage 1
04 is selectively connected to the engagement side and release side of the lock-up clutch 32 in the fluid coupling 10. The lock-up solenoid valve 128 is located in the control chamber 1 of the lock-up control valve 126.
30 and the drain 132, and the solenoid valve 1
28 is off (non-energized state), the secondary hydraulic pressure Pz from the secondary hydraulic oil passage 104 is transmitted to the release side of the lock-up clutch 32, and power is transmitted via the fluid in the fluid coupling 10. . However, when the solenoid valve 128 is on (energized state), the secondary hydraulic pressure Pz from the secondary hydraulic oil passage 104 is supplied to the engagement side of the lock-up clutch 32 and the oil cooler 134, and the power is transferred to the lock-up clutch 32.
transmitted via. Cooler bypass valve 136 controls Tala pressure.

The gear ratio control valve device includes a gear ratio control valve device 138 consisting of a pool valve 142 and a first solenoid valve 144.
and a variable speed switching valve device 140 that includes a second spool valve 146 and a second solenoid valve 148. During the period when the first solenoid valve 144 is off, the spool of the first spool valve 142 is pressed toward the spring 152 by the secondary hydraulic pressure Pz of the chamber 150, and the first line pressure Pβ of the port 154 is
is routed through port 156 of first spool valve 142 to port 158 of second spool valve 146 and to port 160.
The connection between the drain 162 and the drain 162 is broken.

As a result, the gear ratio T is switched in the decreasing direction.

During the period when the first solenoid valve 144 is on, the hydraulic pressure in the chamber 150 is discharged through the drain 164 of the first solenoid valve 144.
The spool of the first spool valve 142 is pushed toward the chamber 150 by a spring 152, and the line pressure Pj is applied to the port 156.
21 does not occur and port 160 is connected to drain 162. As a result, the gear ratio is switched in the increasing direction.

During the period when the second solenoid valve 148 is off, the second spool valve 1
The spool 46 is activated by the spring 1 due to the secondary hydraulic pressure P2 in the chamber 166.
68, the connection between boat 158 and boat 170 is severed, and boat 172 is connected to boat 174. The boats 170 and 172 are connected to the input hydraulic cylinder 50 of the CVT 12. During the period when the second solenoid valve 148 is on, the hydraulic pressure in the chamber 166 is discharged from the drain 176 of the second solenoid valve 148, and the spool of the second spool valve 146 is pressed toward the chamber 166 by the spring 168.
Boat 158 is connected to boat 170 and boat 172
The connection between the boat 174 and the boat 174 is severed. Boat 174 is connected to boat 160 via oil line 180. The orifice 182 is connected to the port 1-1 when the second solenoid valve 148 is turned off.
58 leads a small amount of oil to boat 170. Therefore, during the period when the first solenoid valve 144 is off and the second solenoid valve 148 is on, the input side hydraulic cylinder 50 of the CVT 12
Oil is quickly supplied to the engine, and the gear ratio T quickly decreases. The first solenoid valve 144 is off and the second solenoid valve 148
is off, the input hydraulic cylinder 5 of the CVT 12
0 is supplied through the orifice 182, and the gear ratio T of the CVT 12 gradually decreases. When the first solenoid valve 144 is on and the second solenoid valve 148 is on, oil is not supplied to or discharged from the input hydraulic cylinder 50 of the CVT 12, and the gear ratio γ of the CVT 12 is determined by leakage from the hydraulic cylinder 50. etc., gradually increasing.

During the period when the first solenoid valve 144 is on and the second solenoid valve 148 is off, the oil in the input hydraulic cylinder 50 is discharged from the drain 162, so the gear ratio γ of the CVT 12 increases rapidly.

The gear ratio detection valve 184 is equipped with a rod 194 that is in sliding contact with the movable rotary body 46 on the input side, and the rod 194 is moved in the axial direction by an amount of displacement equal to the displacement amount of the movable rotary body 46 in the axial direction. . The gear ratio detection valve 184 is the CVT 12
As the amount of displacement of the movable rotary body 46 relative to the fixed rotary body 42 on the input side increases, the discharge flow rate of the oil supplied through the orifice 218 increases, so that the gear ratio pressure Pr of the output port 216 becomes equal to the gear ratio γ. It decreases as it increases. The gear ratio pressure Pr is generated by controlling the discharge amount of the hydraulic medium supplied to the output port 216.

The cutoff valve 226 is connected to the mouth 7 cup control well 12.
A chamber 230.6 communicates with the control chamber 130 of No.6 through an oil passage 228. and a spool 234 that moves in relation to the oil pressure in its chamber 230 and the spring force of a spring 232 when the solenoid valve 128 is off, i.e. when the lock-up clutch 32 is in the released state (auxiliary gearshift When shifting gears in the machine 14, the lock-up clutch 32 is released (in order to absorb the shock of the power transmission system), and the lock-up clutch 32 is closed, and the gear ratio pressure P' is transmitted to the primary regulator valve 108. to prevent

The primary regulator valve 108 as a first line pressure generating means is connected to a boat 236. to which the throttle pressure Ptb is supplied. boat 23B supplied with gear ratio pressure Pr;
Boat 240 connected to line pressure hydraulic line 82. Boat 242 connected to the suction side of the oil pump 54.
and through orifice 244 the first line pressure PlI
Boats supplied with 246. A spool 248 that moves axially to control the connection between boats 240 and 242. A spool 250 that biases the spool 248 toward the boat 238 in response to throttle pressure PLh, and a spring 252 that biases the spool 248 toward the boat 238.
It is equipped with Let AI and A2 be the pressure receiving areas of the two lower lands of the spool 248, A3 be the pressure receiving area of the land of the spool 250 that receives the throttle pressure Pth, and let Wl be the acting force of the spring 252, as shown in the following equations (1) and (2). ) holds true.

When the cut-off valve 226 is open and the gear ratio pressure pr is coming to the boat 238, p g t= <83 ・Pth+W1-A1-
Pr)/ (A2-81) ・ ・ ・ ・ ・ (1) When the cut-off valve 226 is closed and the gear ratio pressure pr does not come to the port 238, PI = (＾3・P child shaft l)/ (^2-81)
・ ・ ・ (2) The sub-primary valve 254 as a second line pressure generating means is configured to adjust the first line pressure pH
256. Output port 1-258 where second line pressure pH is generated, boat 260 to which gear ratio pressure P1 is guided. Second line pressure Pt as feedback pressure! 2 is directed through orifice 262 to port 1-264. A spool 266 that controls the opening and closing of the input port 256 and the output port 258. A boat 268 to which the throttle pressure pth is guided. A spool 270 that biases the spool 266 toward the boat 260 in response to throttle pressure Pth from the boat 268. and a spring 272 that biases the spool 266 toward the boat 260.

B1 is the pressure receiving area of the two lands from the bottom of the spool 266.
, B2. The pressure receiving area of the land of the spool 270 that receives the throttle pressure P is B3, and the elastic force of the spring 272 is W.
2, the second line pressure P12 is output according to the following equation (3).

PI2 = (B3・Pth+W2−Bl−Pr)
/CB2-Bl) ・ ・ ・ ・ ・ ・ ・ (3) The shift valve 274 is one of the hydraulic actuators 72 ′ and 74 ′ that actuates the high speed clutch 72 and the low speed brake 74 of the auxiliary transmission 14 . It applies hydraulic pressure to the shift lever, S, L.
Input port 276, output ports 278, 280, orifice 282 to which second line pressure P12 is introduced during range operation
drain oil passage 2 having a drain 284 and terminating in a drain 284;
Boat 288 connected to 86. In the D range, the second line pressure P from the boat 100 of the manual valve 94
12, other control ports) 302, 304, drain 306, spool 308,
and a spring 310 that biases the spool 308 toward the control port 304 . Control port 302,3
A secondary hydraulic pressure Pz is introduced to the control port 302 and 304 through an orifice 312, and the hydraulic pressure at the control ports 302 and 304 is controlled by a shift solenoid valve 314. 2 from the bottom of spool 308
The pressure receiving area of each land is Sl.

B2 and Sl<32. Further, the on/off state of the solenoid valve 314 is controlled in relation to the driving parameters of the vehicle.

When spool 308 is in the spring 310 position, input port 1-276 is connected to output port 278 and output port 280 is connected to boat 288. therefore,
The second line pressure P12 is supplied from the output port 278 to the accumulator 320 having the piston 318 and the high-speed hydraulic actuator 72°, and the pressure inside the low-speed hydraulic actuator 74' is exhausted, so that the sub-transmission 14 becomes a high-speed gear.

When spool 308 is in the position of control boat 304 , input port 276 is connected to output port 280 and output port 278 is connected to drain 306 . Therefore, the second cavity pressure Pff from the output port 280
2 is supplied to the low-speed hydraulic actuator 74'', and the pressure inside the high-speed hydraulic actuator 72'' is exhausted, so that the sub-transmission 14 becomes the low-speed gear.

In the case of the L and S ranges, the second line pressure P12 is not guided to the control port 300, so when the solenoid valve 314 is turned off, the spool 308 initially receives the secondary hydraulic pressure Pz acting on the land of the pressure receiving area S2. Therefore, after that, the pressure receiving area S
Due to the secondary hydraulic pressure Pz acting on land 1, the spring 310
However, when the solenoid valve 314 is turned on, the oil pressure in the control ports 302 and 304 decreases, so the spool 3
Control boat 304 according to the biasing force of spring 3.10
Move to the side. Therefore, in L and S ranges, solenoid valve 3
14, the °C sub-transmission 14 is switched between a high gear and a low gear.

In the D range, the second line pressure P12 is applied to the control port 300.
is guided, so once the spool 308 is in the position on the spring 310 side, the control port 30 is connected to the land of the pressure receiving area S2.
The second line pressure P12 from 0 is applied, and the spool 308 is held at the position on the spring 310 side regardless of whether the solenoid valve 314 is turned on or off thereafter. Therefore, sub-transmission 1
4 is held in high gear.

The shift timing valve 324 has a control boat 326 that communicates with a hydraulic actuator 72° for a high speed gear, and a spool 328 whose axial position is controlled by the hydraulic pressure of the control boat 326, and is configured to shift from a low gear to a high gear. The flow rate of oil supplied to the hydraulic actuator 72' for the high speed gear and the amount of oil discharged from the hydraulic actuator 74'' for the low speed gear are controlled during an upshift.

FIG. 5 shows an electronic circuit that controls the operation of the hydraulic control device described above. An electronic control unit 330 equipped with a so-called microcomputer consisting of a CPU, RAM, ROM, etc. receives information from a sensor (not shown) such as throttle valve opening θ, CV
Rotational speed N, L of the output shaft 34 of T12 (auxiliary transmission 1
4 rotational speed of the input side rotating shaft ntfi), CVTI 2
Signals representing the rotational speed N in * of the input shaft 26 of the input shaft 26, the engine cooling water temperature T, . . . and the operation position Ps of the shift lever are supplied. CPU in electronic control unit 330
Processes the input signal according to a sigma program written in advance in the ROM while utilizing a special memory function of the RAM, and sends a signal to drive the electromagnetic valves 128, 144, 148, and 314 via the amplifier 332. Output each.

In the electronic control device 330, by executing a main routine (not shown), the electronic control device is initialized, input signals from each sensor, etc. are read, and the vehicle speed V is determined based on the read signals. etc. are calculated, and according to the human signal conditions, the engine and CV
Diagnosis to diagnose whether TI2 etc. are operating normally, mutual control between engine computers to control interaction with engine computers that control engine ignition timing, fuel injection amount, etc., and vehicle speed. ■
and a solenoid valve 1 that operates the lock-up clutch 32 based on a predetermined relationship based on the throttle valve opening θ.
Lock-up control for controlling 28, vehicle speed ■, and throttle valve opening θ.

Sub-shift based on the gear ratio [14 gears are set to high gear,
Shift control that automatically switches to one of the lower gears,
The gear ratio control of CVTI2 is repeatedly executed sequentially or selectively.

Hereinafter, the main part of the lock-up control routine executed to control the timing of opening and closing of the lock-up clutch 32 when shifting automatically from a low gear to a high gear of the auxiliary transmission 14 will be explained. The opening control operation of the lock amplifier clutch 32 will be explained according to the flowchart of FIG.

The lock-up control routine is executed in the main routine when it is determined that the engine of the vehicle is in a positive torque state (power-on state) and that the auxiliary transmission 14 is to be shifted up.

First, by executing step S1, the auxiliary transmission 1
4, the solenoid valve 314 that switches the shift valve 274 is turned from the on state to the off state. At the same time, the contents of timer T are reset to zero. This timer T constantly counts clock signals, and the count represents the elapsed time since reset. In the following step S2, CVTI2
The actual gear ratio γ (=Ni, , /N, , t) of Time T3 is determined. This lock-up release command time T is the time from when it is determined that the sub-transmission 14 is to be shifted up until the solenoid valve 314 is brought into the de-energized state. The relationship shown in FIG. 6 is previously stored in the ROM in the form of a data map or a function equation, and also includes an operation delay time, which will be described later. , and C.V.
``The actual lock-up clutch 32 is The opening operation is determined to be reliably executed at an optimal timing during the upshift time (inertia phase time) of the sub-transmission 14.

In step S4, it is determined whether the contents of timer T have reached the lock-up release command time T3 determined in step S3. If it has not yet been reached, step S5 is executed, and the solenoid valve 128 that controls the lock-up clutch 32 is maintained in the on (excited) state, so that the lock-up clutch 32 continues to be in the engaged state. When the count of the timer T reaches T while the execution of steps S4 and S5 is repeated, the determination in step S4 is affirmed and step S6 is executed. In this step S6, the electromagnetic valve 128, which had been in an energized state, is brought into a de-energized (off) state, and the lock-up clutch 32 is brought into a disengaged state after an operation delay time t0. During this operation delay time t0, the lock-up control valve 12 for preempting the lock-up clutch 32
6 and the lock-up clutch 32 are included. Then, by executing step S7, it is determined whether or not the content of timer T has exceeded a predetermined lock-up clutch engagement permission time T4, and if it has not exceeded it yet, execution of step S7 is repeated. is exceeded, step S8 is executed and the solenoid valve 1
28 excitations are permitted. The lock-up clutch engagement permission time T4 may be a fixed time, or may be a function of the gear ratio γ, similar to the lock-up release command time T. Incidentally, FIG. 7 is a time chart showing the operations of the solenoid valve 314, the solenoid valve 128, etc. as a result of the execution of the above steps, and the T0 point in the figure indicates the time when it is determined that the auxiliary transmission 14 should shift up.

Here, the input torque to the auxiliary transmission 14 changes as the gear ratio γ of the CVT 12 changes, and the rotating body located on the front side of the auxiliary transmission 14 at the time of gear change, that is, the variable pulley 36 Since the inertia torque such as .38 changes, the shift time of the sub-transmission 14 changes. However, by repeating the above steps,
The opening timing of the lock-up clutch 32 performed when the sub-transmission 14 is upshifted is based on the actual gear ratio γ of the CVT 12, and the smaller the gear ratio γ is, the earlier the opening timing of the lock-up clutch 32 is. Therefore, in other words, the lock-up release command time T3 is changed to become shorter as the gear ratio γ is on the speed-increasing side.
The shift is reliably executed within the shift time. Therefore, engine revving caused by opening the lock-up clutch too early, and torque fluctuations and deterioration in drivability caused by opening the lock-up clutch too late are suitably prevented.

FIG. 8 shows the relationship between the vehicle speed V and the rotational speed N i of the input shaft 26 using the gear ratio γ in the low gear stage of the sub-transmission 14 as a parameter.
Normally, the gear ratio γ is the shift-up permission gear ratio γ. Upshifting of the auxiliary transmission 14 is permitted in the following areas, that is, the shaded areas in the figure. Therefore, as shown at point A and point B in the figure, for example, the sub-transmission 14 is upshifted at different gear ratios T even at the same vehicle speed. At this time of upshifting, the torque transmitted to the auxiliary transmission 14 and the inertia torque of the rotating bodies located before the auxiliary transmission 14, that is, the variable pulleys 36, 38, etc., differ depending on the gear ratio T of the CVT 12. - The shift time required for upshifting the auxiliary transmission 14 (inertia phase time: shift period required for switching from a low gear to a high gear) differs as shown in FIG. 9 and FIG. 1O. FIG. 9 shows a shift-up state at point A where the gear ratio γ is relatively large, and shows a case where, for example, an appropriate lock-up release command time T3 determined according to the embodiment of FIG. The figure shows an upshift state at point B where the gear ratio γ is relatively small, and shows a conventional case in which the same lock amplifier opening command time T3 as in the case of FIG. 9 is applied. Note that to is the delay time from when the solenoid valve 128 is brought into a de-energized state until the lock-up clutch 32 is actually released.

Conventionally, as shown in FIG. 10, there are cases where the lock-up clutch 32 is released after the shift period of the sub-transmission 14 is completed. Upshifts were performed in the locked state, which caused torsional vibrations in the drive system, impeding drivability. However, according to the embodiment, the lock amplifier opening command time T3 is also determined to be smaller as the gear ratio γ decreases, as shown for example by the dashed line in FIG. That is, the lock-up clutch 32 is released during the inertia phase, and torque fluctuations and deterioration in drivability due to the lock-up clutch 32 being released too late are preferably prevented.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a flowchart illustrating the main part of the operation of the apparatus to which the present invention is applied. FIG. 2 is a schematic diagram showing a power transmission device for a vehicle to which the present invention is applied. Figure 3 is the second
FIG. 3 is a diagram showing the relationship between the range of the sub-transmission and the frictional engagement device in the device shown in the figure. FIG. 4 is a detailed view of the hydraulic control system for operating the device of FIG. 2. FIG. 5 is a block diagram showing an electrical control circuit provided in the device of FIG. 2. FIG. 6 is a diagram showing the relationships used in flowchart 1 of FIG. 1. FIG. 7 is a time chart showing the operation of the solenoid valve for changing the gear stage of the auxiliary transmission and the solenoid valve for controlling the lock amplifier clutch in the embodiment of FIG. FIG. 8 is a diagram showing the relationship between the vehicle speed and the CVT input shaft rotation speed using the gear ratio as a parameter when the auxiliary transmission is in a low gear in the embodiment shown in FIG. 9 and 10 are time charts showing the speed change states at points A and B in FIG. 8. FIG. 10: Fluid coupling 12: CVT 14: Sub-transmission 32: Lock-up clutch Fig. 2

Claims (2)

[Claims] (1) A continuously variable transmission in which engine power is transmitted via a fluid coupling with a lock-up clutch and a gear ratio is changed steplessly, and the continuously variable transmission has at least two forward gears. A control method for a vehicle transmission comprising a sub-transmission connected in series to a rear stage, the lock-up clutch of the fluid coupling being released when the gear stage of the sub-transmission is switched. A method for controlling a vehicle transmission, characterized in that the timing of the lock-up clutch release operation performed when upshifting the auxiliary transmission is changed based on the actual gear ratio of the continuously variable transmission. (2) The timing of the lock-up clutch release operation is performed earlier as the gear ratio of the continuously variable transmission becomes a speed increasing side rather than a decelerating side.
A method for controlling a vehicle transmission described in Section 1.