JPS61290269A - Control device of power transmission device for vehicle - Google Patents

Abstract

PURPOSE:To ensure a high transmission ratio, by a method wherein, when the rapid braking condition of a vehicle is detected, transmittion of a power from a belt type continuously variable transmission gear to driving wheels is shut off. CONSTITUTION:The power of an engine 8 is transmitted to driving wheels 21 through a belt-type continuously variable transmission gear 12 and an auxiliary transmission gear 14. A rapid braking means decides whether a car speed is below a set car speed and actual acceleration is higher than set acceleration, and when it decides that a vehicle is in a rapid braking condition, the auxiliary transmission gear 14 is forced into a neutral state to isolate transmission of a power. This prevents a stop of rotation of a variable pulley, enables the transmission ratio of a transmission gear to be changed to a high value, and provides enough acceleration even during the re-starting.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a control device for a power transmission system for a vehicle equipped with a belt-type continuously variable transmission, and in particular to a technology for improving drivability when restarting a vehicle after sudden braking. It is related to.

A type of conventional power transmission device for vehicles includes a belt-type continuously variable transmission in which the gear ratio is continuously changed by changing the vector diameter of a pair of variable pulleys around which a transmission belt is wound. There is also a type that transmits the power of the engine to the drive wheels via its belt type continuously variable transmission. A vehicle equipped with such a power transmission device has features such as maintaining high fuel efficiency and drivability by operating the engine in an optimal rotation range.

Problems to be Solved by the Invention However, in such conventional vehicles, if sudden braking while driving causes the vehicle to stop or the drive wheels to lock, the variable booster of the belt-type continuously variable transmission cannot rotate. Since the belt stops, the diameter of the transmission belt wound around these variable pulleys no longer changes. Therefore, regardless of the control operation of the control device that attempts to change the gear ratio (rotational speed of the input shaft/rotational speed of the output shaft) to a large value,
Since the change in gear ratio stops midway, when the vehicle restarts, it is not possible to quickly obtain a large gear ratio suitable for starting.
In some cases, sufficient acceleration, or drivability, could not be obtained.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The gist of the system is to include a belt-type continuously variable transmission in which the gear ratio is continuously changed by changing the effective diameter of a pair of variable pulleys around which a transmission belt is wound. A control device for a vehicle power transmission device that transmits power to drive wheels via the belt-type continuously variable transmission, comprising (11) sudden braking detection means for detecting a sudden braking state of the vehicle, and (2) the sudden braking. The present invention further includes a power transmission prevention means for inhibiting power transmission in a power transmission path from the belt type continuously variable transmission to the drive shaft when the detection means detects a sudden braking state of the vehicle.

Operation and Effects of the Invention With this structure, when the sudden braking detection means detects a sudden braking state of the vehicle, the power transmission preventing means prevents power transmission from the belt-type continuously variable transmission to the drive wheels. Since power transmission in the path is blocked, rotation of the variable pulley of the belt-type continuously variable transmission is prevented from stopping when the vehicle is suddenly braked. Therefore, even when the vehicle suddenly brakes, the gear ratio of the belt-type continuously variable transmission is changed to a large value in response to the control operation of the control device, so that when the vehicle is restarted, the gear ratio is large enough to be suitable for starting. This results in sufficient acceleration, or drivability.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

Figure 2 shows the power transmission system of the vehicle, with engine 8
The power is provided by fluid coupling 10. Belt type continuously variable transmission (hereinafter referred to as C
(referred to as VT)12. Sub-transmission 14° intermediate gear device 16.
The signal is then transmitted via the differential device 18 to the drive wheels 21 connected to the drive shaft 20.

The fluid coupling 10 is fixed to the input shaft 26 via 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 a damper 3o. A lock amplifier 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 input shaft 26 and output shaft 34, respectively, and a transmission belt 40 wound around the variable pulleys 36 and 38. The variable pulleys 36 and 38 are connected to the input shaft 2
．． 6 and fixed rotating bodies 42 and 44 fixed to the output shaft 34, and movable rotating bodies 46 and 48 provided to the input shaft 26 and the output shaft 34, respectively, so as to be movable in the axial direction but not relatively rotatable about the axes. As the movable rotating bodies 46 and 48 are moved by the 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 gear ratio γ(
= rotational speed Ni of the input shaft 26, /rotational speed N of the output shaft 34. ut) is now being 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 belt 40 does not slip. The oil pump 54 constitutes a hydraulic power source of a hydraulic control device, which will be described later, and is connected to the crank shaft 22 by a connecting shaft (not shown) passing vertically through the input shaft 26, and is constantly driven to rotate by the engine.

The sub-transmission 14 is provided coaxially with the output shaft 34 of the CVT 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 58, a first planet gear 60 that meshes with the first sun gear 56, and a pair of first and second sun gears.
A second planetary gear 62 that meshes with the sun gear 58 , a ring gear 64 that meshes with the first planetary gear 60 , and a first planetary gear 6
0 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 the engagement between the shaft 68 and the first sun gear 56 , the low speed brake 74 controls the engagement of the first sun gear 56 with the housing, and the reverse brake 76 controls the engagement between the shaft 68 and the first sun gear 56 . control engagement of the housing with respect to the housing. Third
The figure shows the operating state of each frictional engagement element of the sub-transmission 14 and the reduction ratio in each range. As is clear from the figure, the high speed clutch 72, the low speed brake 74,
When the frictional engagement device constituted by the reverse brake 76 is in a non-operating (non-engaged) state, power transmission is blocked.
In this embodiment, the sub-transmission also serves as power transmission blocking means. In the figure, the ◯ mark indicates the locked state, the x mark indicates the released state, and ρ1 and ρ2 are gear ratios defined by the following equation.

ρ1−Z□/Z.

ρ2 ” Z −z/ Z r However, ZS+ is the number of teeth of the first sun gear 56, and 212 is the number of teeth of the second sun gear 56.
The number of teeth of the sun gear 58, Z, is the number of teeth of the ring gear 64.

Therefore, in the low speed gears in the L and D ranges, the low speed brake 74 is operated and the first sun gear 56
is fixed, power is transmitted at the reduction ratio (1+ρ1/ρ2), but in the high gears of L and D ranges, the entire planetary gear system rotates as a unit due to the operation of the high gear clutch 72. As a result, power is transmitted 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 power is transmitted through reverse rotation at the gear ratio (1-1/ρ2).

Returning to FIG. 2, the output gear 70 of the sub-transmission 14 is connected to the differential bag W18 via the intermediate gear device 16, and the engine power is transmitted to the left and right drive shafts 20 in the differential device 18.
The power is then distributed to the left and right drive wheels.

4, 5, and 6 show a hydraulic control circuit for controlling the vehicle power transmission device shown in FIG. 2. FIG. The oil pump 54 pumps the hydraulic oil returned into the oil tank (not shown) to the suction line oil passage 82 through the strainer 80.

The throttle valve 84 generates a throttle pressure PLh corresponding to the throttle valve opening θTH on its output boat 86. The spool 88 of the throttle valve 84 receives an acting force that increases as the throttle valve opening θ7H increases from a throttle cam 90 that rotates together with the throttle valve provided in the intake pipe of the engine 8, and a feedback pressure from the control boat 92. The opening and closing of the line oil passage 82 and the output boat 86 is controlled by receiving the throttle pressure P in the opposite direction. The manual valve 94 is set to the shift lever (low), D (drive), and neutral (N).

It is positioned in the axial direction in relation to the R (reverse) and P (parking) range operations, and supplies the first line pressure P11 of the line oil passage 82 to the boat 96 when in the R range.
It is led to port 98 when in the L range, and to ports 98 and 100 when in the D range. Relief valve 102. teeth,
It has a function as a safety valve that releases oil in the line oil passage 82 when the first line pressure pH of the line oil passage 82 exceeds a predetermined value.

The secondary hydraulic oil passage 104 is connected to the line oil passage 82 via an orifice 106 and a boat 110 from which excess oil of the primary regulator valve 108 is discharged, and the secondary regulator valve 112 is connected to the line oil passage 82 via the orifice 114. Control room 11 connected to channel 104
6, controls the connection between the secondary hydraulic oil passage 104 and the boat 120 in relation to the oil pressure in the control room 116 and the load of the spring 118, and sets the secondary oil pressure Pz of the secondary hydraulic oil passage 104 to a predetermined value. to be maintained. Lubricating oil passage 122 is connected to secondary hydraulic oil passage 104 via boat 120 or 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 solenoid valve 128 is connected to the control chamber 130 of the lock-up control valve 126 and the drain 13.
When the solenoid valve 128 is off (de-energized), the secondary hydraulic pressure Pz from the secondary hydraulic oil passage 104 is transmitted to the release side of the lock amplifier clutch 32, and the power is transferred to the fluid coupling 10. transmitted via.

However, when the solenoid valve 128 is on (energized), the engagement side of the lock-up clutch 32 and the oil cooler 13
4 is supplied with secondary hydraulic pressure Pz from a secondary hydraulic oil passage 104, and power is transmitted via the lock-up clutch 32. Cooler bypass valve 136 controls Tala pressure.

The speed ratio control device includes a speed change direction switching valve device 138 consisting of a first spool valve 142 and a first solenoid valve 144, and a second spool valve 142 and a first solenoid valve 144.
A variable speed switching valve device 140 including a spool valve 146 and a second electromagnetic valve 148 is provided. No. 1 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 P/1 of the boat 154 is
The water is sent to the boat 158 of the second spool valve 146 via the boat 156 of the spool valve 142, and the connection between the boat 160 and the drain 162 is cut off.

As a result, the gear ratio γ 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, and the spool of the first spool valve 142 is held in the chamber by the spring 152.
50 , there is no first line pressure Pffil on the boat 156 and the boat 160 is connected to the drain 162 . As a result, the gear ratio is switched in the increasing direction.

During the period when the second magnetic 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.
6B, the connection between boats 158 and 170 is severed, and boat 172 is now connected to boats 1-174. Bow 1-170.172 is connected to the input hydraulic cylinder 50 of the CVT 12 via an oil passage 176. During the period when the second solenoid valve 148 is on, the hydraulic pressure in the chamber 166 is discharged from the drain 178 of the second solenoid valve 148, and the spool of the second spool valve 146 is turned on by the spring 168.
66, boat 158 is connected to boat 170, and boats 172 and 174 are disconnected. Boat 174 is connected to boat 160 via oil line 180. The orifice 182 supplies a small amount of oil from the boat 158 to the boat 17 when the second solenoid valve 14 is turned off.
Lead to 0. Therefore, during the period when the first solenoid valve 144 is off and the second solenoid valve 148 is on, hydraulic oil is quickly supplied to the input hydraulic cylinder 50 of the CVT 12, and the gear ratio γ is rapidly reduced. During the period when the first solenoid valve 144 is off and the second solenoid valve 148 is off, oil is supplied to the input hydraulic cylinder 50 of the CVT 12 through the orifice 1.
82, 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.
The gear ratio γ of No. 2 gradually increases according to leakage from the hydraulic cylinder 50 and the like. When the first solenoid valve 144 is on and the second
During the period when the solenoid valve 148 is off, the input hydraulic cylinder 5
0 oil is discharged from the drain 162, so the CVT
The gear ratio γ of 12 increases rapidly.

The gear ratio detection valve 184 is shown in detail in FIG. Sleeves 186, 188 are coaxially disposed within bore 190 and are axially secured by snap ring 192. A rod 194 passes through the end of the sleeve 186 and has a spring seat 196 fixed to the tip. Another support 198 fixed to one end of the rod 194 is connected to the movable rotating body 4 on the input side.
6, and moves the rod 194 in the axial direction by an amount of displacement equal to the amount of displacement in the axial direction of the movable rotating body 4G.

Spool 200 has lands 202, 204 and is axially movably fitted within sleeve 188. Land 202 is space 206 between lands 202 and 204
The land 2 has a passage 210 that communicates with the oil chamber 208.
04 controls the opening area of the boat 212 of the sleeve 188 into the space 206. The boat 212 is connected to the drain 214 through a space on the outer peripheral side of the sleeve 186.

The oil chamber 208 is an output port 216 that generates a gear ratio pressure Pr.
The output boat 216 is connected to the line oil passage 82 via an orifice 218. The spring 220 is provided between the spring seat 196 and the sleeve 188 and biases the rod 194 in the direction of pushing it out of the sleeve 186.
The spring seat 196 is provided between the spring seat 196 and the flange 224 of the spool 200 to urge the spool 200 toward the oil chamber 208.

Therefore, as the amount of displacement of the movable rotor 46 relative to the fixed rotor 42 on the input side of the CVT 12 increases, the gear ratio γ increases. As the rod 194 is pushed out of the sleeve 186 due to the increase in displacement of the movable rotary body 46, the oil chamber 2
The force applied to the spool 200 by the spring 222 in the 08 direction decreases.

As a result, the spool 200 moves toward the rod 194, and the land 204 increases the opening area of the boat 212 to increase the oil discharge flow rate, so that the gear ratio pressure Pγ of the output boat 216 decreases. The gear ratio pressure Pγ is the output boat 21
6, the upper limit thereof is defined as the first line pressure Pfl.

The broken lines in FIGS. 8 and 9 indicate the gear ratio pressure Pr and the gear ratio γ.
This example shows two relationships. As described below, the first
The line pressure Pfl decreases as the gear ratio T decreases, but at the gear ratio T (where the gear ratio pressure Pr becomes equal to the line pressure pH)
When the gear ratio γ is a function of the throttle pressure Ptk and therefore the engine output torque Te, the gear ratio becomes Pr-pH in the gear ratio range below that. In addition, in FIG. 8 and FIG. 9, the two-dot chain line is the ideal value of the first line pressure pH, and Tl>T2.

The cut-off valve 226 is the lock-up control valve 126.
The chamber 2 communicates with the control chamber 130 via an oil passage 228.
30. 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 changing gears in the machine 14, the lock-up clutch 32 is released to absorb shocks in the power transmission system), and the lock-up clutch 32 is released to absorb the shock of the power transmission system. prevent.

The primary regulator valve lO8 as the first line pressure generating means is connected to the boat 236. to which the throttle pressure Pth is supplied. a boat 238 to which the gear ratio pressure Pr is supplied;
Boat 240 connected to line oilway 82. Boat 242 connected to the suction side of the oil pump 54. and boat 246 . supplied with a first line pressure pH via orifice 244 . A spool 24 that moves axially to control the connection between boats 240 and 242.
8. It includes a spool 250 that biases the spool 248 toward the boat 238 in response to throttle pressure Pth, and a spring 252 that biases the spool 248 toward the boat 238. Assuming that the pressure-receiving areas of the two lower lands of the spool 248 are A1 and A2, the pressure-receiving area of the land of the spool 250 that receives the throttle pressure P is A3, and the acting force of the spring 252 is Wl, the following equation (1) and ( 2)
holds true.

When the cut-off valve 226 is open and the gear ratio pressure Pγ is applied to the boat 238, Pl=(83・P+Wl−AI・Pr)/(A
2-81) (1) When the cut-off valve 226 is closed and the gear ratio pressure Pr is not coming to the boat 238, Pl = (A3・P+1)/(A2-At)...・
・(2) Note that the line pressure Pβ of equations (11 and (2))
1 is shown by a solid line and a dash-dotted line in FIGS. 8 and 9, respectively.

In FIG. 6, the sub-primary valve 254 as the second line pressure generating means is set to the first line pressure PI! in the L and D ranges. 1 is manual pulp 94 boat 98
Input port 256° second line pressure P12 led from
is generated at the output port 258, and the output port 260. A boat 264 through which a second line pressure PI12 as a feedback pressure is guided through an orifice 262; a spool 266 that controls the opening and closing of the input port 256 and the output port 258; a boat 268 through which the slow/torre pressure P is guided; A spool 270 that biases the spool 266 toward the boat 260 in response to throttle pressure P from the boat 268. and a spring 272 that biases the spool 266 toward the boat 260. The pressure receiving areas of the two lands from the bottom of the spool 266 are Bl and B.
2. The pressure receiving area of the land of the spool 270 that receives the throttle pressure Pub is B3, and the elastic force of the spring 272 is W2.
When these are respectively defined, the following equation (3) holds true.

P12=(83・P+W2−Bl・Pγ)/(B2
-Bl)...(3) The sub-primary valve 254 supplies the second line oil pressure P12 regulated according to the above equation (3) to the shift valve 274 via the switching valve device 290, and also supplies the second line oil pressure P12 to the shift valve 274 via the switching valve device 290. act on the piston 318. FIG. 10 shows the relationship between the second line pressure P12 output from the sub-primary valve 254 and its ideal value.

The switching valve device 290 includes a solenoid valve 291 and a spool valve 2.
92, and in response to the operation of the solenoid valve 291,
A transmission state that allows transmission of the second line pressure PN2 output from the sub-primary valve 254, and an exhaust pressure state that exhausts the second line pressure P12 and prevents the transmission when the vehicle suddenly brakes. It can be switched all at once. That is, the spool valve 292 has an input port 293 to which the second line pressure P12 is supplied from the sub-primary valve 254, an output port 294 that outputs the second line pressure P12, a drain boat 295, and an output port 294. Input port 293 or drain boat 295
The spool 296 is selectively connected to the spool 296.
When the secondary hydraulic pressure Pz is applied to one end surface of the spool 296, the spool 296 is moved against the biasing force of the spring 298 and placed in the above-mentioned transmission state. The secondary hydraulic pressure Pz is supplied to the electromagnetic valve 291 via an orifice 297, and when the electromagnetic valve 291 is in an excited state, the downstream side of the orifice 297 is exhausted and the secondary hydraulic pressure Pz is supplied to the spool 29.
Although the secondary hydraulic pressure Pz does not act on the spool 296 when the electromagnetic valve 291 is in a de-energized state, the secondary oil pressure Pz acts on the spool 296.

Therefore, transmission of the second line pressure PR2 output from the sub-primary valve 254 in response to the energization and de-energization of the solenoid valve 291 is blocked or allowed.

Shift pulp 274, second line pressure Pjl when in L range! Input port 276 led 2, output port 2
78,280, a boat 288. connected to a drain line 28G having an orifice 282 and terminating in a drain 284. A control boat 300 to which the first line pressure Pfl is supplied from the boat 100 of the manual valve 94 in the D range, other control boats 302, 304, a drain 306, a spool 308, and the spool 308 thereof.
The control boat 304 has a spring 310 that biases the control boat 304 toward the control boat 304 . Control boats 302 and 304 have orifices 312
A secondary hydraulic pressure Pz is guided through the hydraulic pressure Pz. Further, the oil pressure of the control boats 302 and 304 is controlled by a solenoid valve 314. The pressure receiving areas of the two bottom lands of the spool 308 are each Sl.

S2, and Sl<32. Further, the on/off state of the solenoid valve 314 is controlled in relation to the driving parameters of the vehicle, and when the solenoid valve 314 is on, oil is discharged from the drain 316.

When spool 308 is in the spring 310 position, input port 276 is connected to output port 278 and output port 280 is connected to boat 288. Therefore, the seventh line pressure Pj22 is supplied from the output port 278 to the accumulator 320 having the piston 318 and the high-speed clutch 72, and the sub-transmission 14 becomes the high-speed gear.

When the spool 308 is in the position on the control port 304 side, the input port 276 is connected to the output port 280 and the output port 278 is connected to the drain 306. Therefore, the second line pressure Pj72 from the output port 280 is supplied to the low speed accumulator 322, and the sub-transmission 1
4 is a low speed gear.

In the case of the L range, the first line pressure pH is not introduced to the control boat 300, so when the solenoid valve 314 is turned off, the spool 308 initially receives the secondary hydraulic pressure Pz acting on the pressure receiving surface, the land with the product S2. Then, the secondary hydraulic pressure Pz acting on the land of the pressure receiving area S1 moves the spring 3 to the 10 side, but when the solenoid valve 314 is turned on, the control boat 3
Since the oil pressure of 02 and 304 decreases, the spool 308 moves toward the port 304 according to the biasing force of the spring 310. That is, in the L range, the sub-transmission 142 is switched between a high gear position and a low gear position in conjunction with turning on and off the solenoid valve 314.

In the D range, the first line pressure P11 is applied to the control boat 300.
is guided, so once the spool 308 is in the position on the spring 310 side, the control boat 30 is placed on the land of the pressure receiving area S2.
A first line pressure pH 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, the sub-transmission 14
is held in the high speed stage.

The shift timing valve 324 is connected to the high speed clutch 7.
2, and a spool 328 whose axial position is controlled by the oil pressure of the control boat 326, and is used to supply oil to the high speed clutch 72 when upshifting from a low speed to a high speed. The supply flow rate and the amount of oil discharged from the low speed brake 74 are controlled.

FIG. 11 shows an electronic circuit that controls the operation of the hydraulic control device described above. Electronic control device 330 equipped with a so-called microcomputer consisting of a CPU, RAM, ROM, etc.
The throttle valve opening θ and C are measured from a sensor (not shown).
Rotational speed N in of input shaft 26 of VT12 and rotational speed Nout of output shaft 34 + Engine coolant temperature T, 4
．． Signals each representing the operating position P of the shift lever are supplied. Further, the electronic control device 330 is supplied with a signal SP representing a brake pedal operation from a brake switch 332 for detecting an operation of a brake pedal (not shown). The CPU in the electronic control unit 330 processes input signals according to a program stored in advance in the ROM while utilizing the temporary storage function of the RAM, and controls the solenoid valves 128 and 14.
Signals for driving 4, 148, 291, and 314 are outputted through the amplifier 334, respectively.

Next, regarding the operation during sudden braking of the vehicle, the above-mentioned RO
A description will be given of the sudden braking control routine shown in FIG. 12, which shows a part of the program stored in M. Note that, prior to the sudden braking control routine, the vehicle speed V, vehicle acceleration α, C
The gear ratio T of the VT 12 is calculated in advance in a step not shown based on a signal representing the rotational speed N t n of the input shaft 26 of the CVT 12 and a signal representing the rotational speed N o u L of the output shaft 34 .

First, the value of the flag F is determined in step SO, and if F=O, the process proceeds to step S1, and if F=1, the process proceeds to step S.
Proceed to step 7. Note that the flag F is used to indicate that the sub-transmission 14 is in a neutral state, and its initial value is O.

In step S1, it is determined whether or not the brake pedal is being operated based on the signal SP. If the determination is negative, that is, if the brake pedal is not being operated, step S9 is executed and a flag is flagged. F is reset to 0, and then step S2 is executed to de-energize the solenoid valve 291. Therefore, the second line pressure Pβ2 output from the sub-primary valve 254 is supplied to the shift valve 274 (A) through the switching valve device 290, and the high-speed clutch 72 and the low-speed brake 74 are enabled to operate. However, if the determination in step S1 is affirmative, that is, if the brake pedal is being operated, the next step S3 is executed and the vehicle speed is
It is determined whether or not the vehicle speed vA is lower than a preset vehicle speed vA. When the vehicle speed V is high to a certain extent, the drive wheels 21 are rotating even in a braking state, so it may be better to apply engine brake to the drive wheels 21 at the vehicle speed vA rather than to prevent power transmission. .

The set vehicle speed vA is used to determine the range.

In step S3, if it is determined that the vehicle speed is higher than the set vehicle speed VA, steps S9 and S2 are executed, but if it is determined that the vehicle speed is lower than the set vehicle speed VA, the next step corresponding to the sudden braking detection means is executed. Step S4 is executed to determine whether the actual acceleration α (negative value) of the vehicle is larger than a preset acceleration α. When the actual acceleration α is large to some extent (close to zero)
Since the braking state is not sudden and the drive wheels 21 are rotating, it may be better to apply engine brake to the drive wheels 21 at the vehicle speed vA rather than to prevent power transmission. The above-mentioned set acceleration α is for determining the area.

If it is determined in step S4 that the acceleration α of the vehicle is larger than the set acceleration α, then step S4
9 and S2 are executed, but if it is determined that the acceleration is smaller than the set acceleration α, the next step S5 is executed to determine whether the gear ratio T of the CVT 12 has reached its maximum value γ1,8. is judged. When it is determined that the gear ratio γ of the CVT 12 has reached its maximum value γ,□,
Since there is no need to disconnect between the CVT 12 and the drive wheels 21 during sudden braking, steps S9 and S2 are executed, but if it is determined that the gear ratio γ has not reached its maximum value r wax , after the flag F is set to 1 in step S8 in order to change the gear ratio T to the maximum value T1.8, step S6 is executed to change the second pulp to be supplied from the sub-primary pulp 254 to the shift valve 274. The transmission of the line pressure P12 is blocked. and,
Step SO is executed again to determine the contents of flag F, but step S8. After executing S6, flag F
Since the content of is rlJ, step S7 is executed. Step S7 determines whether or not the accelerator pedal is not operated by the throttle valve opening θTl.
If the determination is negative, the steps S9 and S2 are executed, but if the determination is affirmative, the steps from step 85 are executed. Therefore, once sudden braking is detected in step S4, unless the accelerator pedal is operated again, the high-speed clutch 72, which is a frictional engagement device, Since the engagement operation of the low-speed gear brake 74 is disabled, the auxiliary transmission 14 is brought into a neutral state and power transmission is blocked. As a result, vehicle acceleration α (negative) due to brake pedal operation
In a sudden braking condition where the acceleration is less than the set acceleration α,
Even if the CVT 12 and the drive wheels 21 are disconnected and the vehicle stops or the wheels are locked, the rotation of the input shaft 26 and output shaft 34 of the CVT 12 is maintained. The gear ratio T is changed. During sudden braking, the vehicle speed V is significantly lower and the throttle valve opening θTH is also small, so the gear ratio γ of the CVT 12 is set to its maximum value γ, □.

As described above, according to this embodiment, when the vehicle suddenly brakes, C
Since the power transmission in the power transmission path between the VT 12 and the drive wheels 2 is blocked and the rotation of the input shaft 26 and output shaft 34 of the CVT 12 is prevented from stopping, the gear ratio γ of the CVT 12 is controlled by the control operation of the control device. It can be changed to a larger value in response. Therefore, when restarting after sudden braking, a large gear ratio T suitable for starting can be obtained, and sufficient acceleration performance, that is, drivability can be obtained.

Although one embodiment of the present invention has been described above based on the drawings,
The invention is applicable to other aspects as well.

For example, in the above-mentioned embodiment, power transmission is blocked by placing the sub-transmission 14 in the neutral state, but the clutch, which is released from the engaged state during sudden braking, is
It may be provided between T12 and the drive wheel 21.

Further, in the above embodiment, sudden braking of the vehicle is determined based on the acceleration α of the vehicle, but it may also be determined based on the pressure of the brake fluid that transmits the braking operation force.

Note that 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 the drawing]

FIG. 1 is a diagram corresponding to claims of the present invention. FIG. 2 is a schematic diagram showing a vehicle power transmission system controlled by an embodiment of the present invention. FIG. 3 is a diagram showing the relationship between the range of the auxiliary transmission included in the power transmission device of FIG. 2 and the frictional engagement device. 4 to 6 are circuit diagrams showing in detail a hydraulic control system for operating the apparatus of FIG. 2. 7th
This figure 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 oil pressure shown in FIGS. 4 to 6. FIG. FIG. 10 is a graph showing the characteristics of the second line oil pressure shown in FIGS. 4 to 6. 1st
FIG. 1 is a block diagram showing a control circuit of the device shown in FIG. FIG. 12 is a flowchart showing the operation of the control circuit of FIG. 11. 8: Engine blocking means) 36.38: Variable pulley 40: Transmission belt Step S4: Sudden braking detection means Applicant: Toyota Motor Corporation Fig. 1 □ - Cut-off valve opening life PIT - - Force cut-off valve' Explaining the pH of the temple - 111 Pi
1 value 1 gear ratio r 9th factor 1 --- 7'77 4 value □ Cut-off valve 'fljl@e's Plf-11 force
Maximum pH value when the valve is closed
Minimum value - Gear ratio r Fig. 10 - Maximum value of PIE month 2, 21 shift
Minimum shift sinkr

Claims (2)

[Claims] (1) Includes a belt-type continuously variable transmission in which the gear ratio is continuously changed by changing the effective diameter of a pair of variable pulleys around which a transmission belt is wound. A control device for a vehicle power transmission device that transmits power to drive wheels via a step-change transmission, comprising: sudden braking detection means for detecting a sudden braking state of the vehicle; and a sudden braking detection means for detecting a sudden braking state of the vehicle. A control device for a power transmission device for a vehicle, characterized in that the control device comprises: power transmission prevention means for inhibiting power transmission in a power transmission path from the belt-type continuously variable transmission to the drive wheels when the belt type continuously variable transmission is detected. (2) The power transmission device includes an auxiliary transmission provided after the belt-type continuously variable transmission, and the power transmission blocking means operates a friction engagement device of the auxiliary transmission. 2. The control device for a power transmission device for a vehicle according to claim 1, wherein the hydraulic pressure for the vehicle is discharged when the vehicle is in a sudden braking state.