JPH02180366A - Control unit for automatic transmission for vehicle - Google Patents

Abstract

PURPOSE:To prevent the life lowering of a non-stage transmission with unnecessary change gear eliminated by stopping the change gear of the non-stage change gear device when a travel condition is in a very-slow or a slow speed travel region and a torque ratio is in an under-drive side. CONSTITUTION:In an electronic control unit 120, travel conditions of a vehicle are classified into very-slow speed, slow speed, and normal travel regions based on the signal of a speed sensor 167. The change gear of a non-stage transmission 30 is prevented in the very-slow speed travel region where the number of revolution of a primary or secondary pulley 31 or 32 can not be correctly detected with sensors 165 and 166. And the change gear of a non-stage change gear device 30 is stopped too when a torque ratio is in an under drive side in the slow speed travel region. Consequently since the slow speed travel region is surely passed when a vehicle is stopped, the vehicle can be stopped with the device 30 surely made to the condition of the maximum torque ratio, and restarting can be made with the maximum torque ratio. Thus unnecessary change gear is eliminated and life lowering can be prevented.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an automatic transmission for a vehicle, in particular, an endless belt having a V-shaped or trapezoidal cross section is stretched between two variable pulleys. The present invention relates to a control device for an automatic transmission for a vehicle that continuously changes the rotational speed ratio between the shafts of two variable pulleys by changing the radial position in contact with the variable pulleys.

(Prior art) Conventionally, belt-type continuously variable transmissions require a gear mechanism for reversing in order to be used in vehicles, and there is also a limit on the diameter of the variable pulley, making it difficult to use a large reduction ratio. Therefore, it is necessary to make the reduction ratio between the output shaft and the wheel drive shaft larger than that of a gear type transmission, but the structure is f! Since it is Jl and has a small size, it is suitable for integrally incorporating a prime mover, a transmission, and a differential.

This conventional belt-type continuously variable automatic transmission for vehicles has a structure in which an endless belt connects a primary pulley supported on the input shaft side and a secondary pulley supported on the output side. The primary pulley and the secondary pulley each include a fixed flange and a movable flange that moves relative to the fixed flange.

Further, a forward/reverse switching device is formed by a multi-disc clutch, a planetary gear device, and a multi-disc brake, and the forward/reverse switching device is disposed on the input shaft side or output shaft side of the variable pulley consisting of the primary pulley and secondary pulley. This is used to switch the vehicle forward or backward.

Incidentally, the movement of the movable flange with respect to the fixed flange and the operation of the multi-disc clutch and multi-disc brake of the forward/reverse switching device have conventionally been performed using hydraulic pressure such as line pressure. When hydraulic pressure is used, it is possible to transmit pressure over long distances, and it is also possible to obtain large driving force with a small device.

However, on the other hand, if dust gets into the oil, it is likely to cause malfunctions, the viscosity changes due to changes in oil temperature and the output efficiency changes, and if the oil pressure temporarily drops, it may cause malfunctions. In this case, the endless belt slips and power cannot be transmitted.Furthermore, it takes time for the actuator to actually operate after the operator starts the operation.
In cases where the responsiveness is not good, especially when driving a car, it is desirable to be able to immediately obtain the corresponding driving condition by the driver's operation, so it was necessary to improve the responsiveness and operational feeling. .

Therefore, an automatic transmission for a vehicle is provided in which an electric motor is used to move the movable flange relative to the fixed flange, and to operate the multi-disc clutch and multi-disc brake of the forward/reverse switching device.

In the above-mentioned automatic transmission for a vehicle, the position of the movable flange is changed by operating and rotating the electric motor, thereby changing the speed. Therefore, it is possible to prevent the valve from malfunctioning due to oil leakage or dust entering the pond, and when the operator operates, the information is transmitted to the electric motor by an electric signal. Therefore, the corresponding driving state can be obtained immediately.

Further, the automatic transmission for vehicles has a system consisting of a continuously variable transmission that transmits power via two variable pulleys, and a system that bypasses the continuously variable transmission and transmits power via a transfer device. It has a system consisting of an auxiliary transmission device that
As a result, switching between low-speed mode and high-speed mode is now possible.

The low-speed mode increases the system torque ratio to facilitate starting, and the high-speed mode improves torque transmission efficiency.

By the way, the automatic transmission for a vehicle having the above configuration has a torque ratio between the input side and the output side of the above continuously variable transmission consisting of two variable pulleys, or both the continuously variable transmission and the auxiliary transmission. Various IIJi2j are performed by calculating the system ratio between the input end and the output side of the system I, but for this purpose, it is necessary to detect the primary pulley rotation speed and the secondary pulley rotation speed. A tm pick amplifier is used as a means for detecting both rotational speeds.

The magnetic pickup is made up of a rotating body part, that is, a magnetic body provided on both pulleys, and a magnetic field formed in a stationary part, and the state in which the magnetic field is interrupted as the rotary body part rotates is pulsed. It is designed to detect the rotation speed and output the rotation speed.

(Problems to be Solved by the Invention) However, in the conventional automatic transmission for a vehicle, the above-mentioned ? It c11 pickup can detect the rotation speed relatively easily when the vehicle is running at high speed and both pulleys are rotating at high speed, but when the vehicle is running at extremely low speed. If both pulleys are rotating at low speed, it may be difficult to read the pulse.

In such cases, the rotation speed could not be detected accurately and the belt position could be misjudged, resulting in incorrect gear shifting. Trying to do so may shorten the life of the continuously variable transmission, or may not perform a downshift when it is required, making it difficult to start.

On the other hand, in order to accurately detect the rotational speed, it may be possible to increase the size of the electromagnetic pink amplifier to improve the sensitivity, but this is likely to be affected by noise and the size of the device will increase accordingly. It is also possible to increase the number of teeth formed on the rotor to generate pulses to make pulse detection easier, but the processing to form the teeth is difficult and the manufacturing cost is high. It gets high °ζ.

The present invention eliminates the problems of the conventional automatic transmission for vehicles and prevents erroneous gear shifting when the rotation speed cannot be accurately detected without making any changes to the electromagnetic pink amplifier part. It is an object of the present invention to provide a braking device for a vehicle automatic transmission that is capable of controlling the vehicle automatic transmission.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides an endless bell (33) with a V-shaped or trapezoidal section between two variable pulleys (31) and (32). Hand over the endless belt (33
) is used for vehicles that steplessly converts and outputs the engine rotational speed transmitted via a fluid transmission device by changing the radial position where the variable pulleys (31) and (32) contact each other. In the automatic transmission control device, a means (167) for detecting vehicle speed is provided, and the driving state of the vehicle is divided into an extremely low speed driving area, a low speed driving area, and a normal driving area based on the detected vehicle speed.

A means is provided for stopping the gear change of the continuously variable transmission (30) when the running state is in the extremely low speed range, or when the running state is in the low speed range and the torque ratio is on the underdrive side. ing.

The relative position is electric 1! Variable pulley (3) consisting of a fixed flange and a movable flange that can be changed by (101)
1) and (32) are provided facing each other, and an endless belt (33) with a V-shaped or trapezoidal cross section is stretched between the two variable pulleys (31) and (32).
33) are the respective variable pulleys (31) and (32)
By changing the 1' radial position in contact with
The above control device can also be applied to a control device for a vehicle automatic transmission that continuously converts and outputs the engine rotation speed transmitted through a fluid transmission device.

(Operation and Effect of the Invention) According to the present invention, the means (1) for detecting vehicle speed as described above is provided.
67) is provided, and the driving condition of the vehicle is divided into an extremely slow driving area, a low speed driving area, and a normal driving area according to the detected vehicle speed, and when the driving condition is in the extremely slow driving area, the continuously variable transmission (30) Since the speed change of the primary pulley (31) or the secondary pulley (32) is difficult to detect accurately, an erroneous speed change is not performed in an extremely low speed driving range.

Also, when the driving condition is in the low speed range and the torque ratio is on the underdrive side, the continuously variable transmission (30
), the subsequent shifting of the continuously variable transmission (30) is stopped.

When the vehicle stops, it always passes through this low-speed travel region, so the continuously variable transmission (30) can be reliably brought to a maximum torque ratio state and stopped. Therefore, it becomes possible to start the vehicle after stopping with the maximum torque ratio.

After that, the continuously variable transmission (30) does not change gears, so unnecessary gear changes are eliminated.
) can be prevented from decreasing the lifespan.

In the above description, each element is given a reference numeral for convenience of explanation, but these do not limit the configuration of the present invention.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an operation flow diagram of a control device for a vehicle automatic transmission showing an embodiment of the present invention, FIG. 2 is a schematic diagram of the vehicle automatic transmission, and FIG. 3 is a diagram showing various positions of the vehicle automatic transmission. FIG. 4 is a functional diagram of a control system for a vehicle automatic transmission, and FIG. 5 is a control block diagram of the vehicle automatic transmission.

First, the automatic transmission for vehicles according to the present invention, particularly the automatic transmission for vehicles to which the control device for the automatic transmission for vehicles is applied, will be explained along the schematic diagram shown in FIG. 2. An input device 10 consisting of a fluid coupling 11 and a lock-up clutch 12, an auxiliary transmission 40, a primary pulley 31,
A continuously variable transmission device 30 consisting of a secondary pulley 32 and an endless belt 33 with a figure 7 or trapezoidal cross section, and a reduction gear device 7
1 and a differential gear device 72.

The auxiliary transmission device 40 includes a low-high-speed mode switching device 20 consisting of a transfer device 80, a single planetary gear device 21, a mode switching engagement device 22, and a dual planetary gear device! 91 and reverse planid B2,
A forward/reverse switching device 90 including a forward clutch C1 is provided.

The single planetary gear device 21 includes a first element 21R (
or 21S), a second element 21C connected to the output member 70 of the continuously variable transmission IQ1, and an input shaft 6 from the input device 1O.
0 via a transfer device 80.

Further, a mode switching engagement device 22 for switching the single planetary gear device 21 between high speed mode H and low speed mode includes a locking means consisting of a row one-way clutch F and a low coast reverse brake n1, and a high clutch C2. The locking means F, formerly known as the locking means F, is a third element 2 which becomes a reaction force support member when used as a deceleration mechanism in low speed mode L.
15 (or 21R) via a transfer device 80, and the high clutch C2 is connected to the input shaft 6
0 and the third element 215 (or 21R). That is, the ring gear 21R of the single planetary gear device 21 is interlocked with the output part 30a of the continuously variable transmission 30, and the carrier 21C is interlocked with the output member 70,
Then, the sun gear 215 is interlocked with the low one-way clutch F and the low coast reverse brake ill through the transfer device 80, and the high clutch C2
It is linked to.

In addition, dual planetary gear device f! 91, the sun gear 915 is connected to the input shaft 60, and the carrier 91
C is connected to the input portion 30b of the continuously variable transmission 30 and is also connected to the input shaft 60 via the forward clutch C1, and the ring gear 91R is connected to the reverse brake B2.

Each clutch, brake, and one-way clutch in the automatic transmission for a vehicle having the above structure operates as shown in FIG. 3 in each position. The ON state of each element is indicated by a circle, and the * mark indicates that the lock-up clutch 12 can be operated as appropriate.

To explain this in detail, in the low speed motor FL in the D range, the forward clutch C1 and the row one-way clutch F operate. In this state, the rotation of the engine crankshaft is controlled by the lock-up clutch 12 or the fluid coupling 1.
1 to the input shaft 60, further directly to the sun gear 915 of the dual planetary gear device ff91, and also to the carrier 91C via the forward clutch CI. Therefore, the dual planetary gear device 91 rotates integrally with the input shaft 60, transmits the rotation in the forward direction to the input section 30b of the continuously variable transmission 30, and further rotates the rotation as appropriate by the continuously variable transmission 30. is transmitted from the output section 30a to the ring gear 21R of the single planetary gear device 21. On the other hand, in this state, the sun gear 21S, which is a reaction force support element that receives reaction force, is stopped by the row one way lasso F through the transfer device 80, and therefore the ring gear 21S
The rotation of 1R is taken out from the carrier '72] and C as a deceleration rotation, and is further transferred to the deceleration gear device 71 and the differential gear device 72.
is transmitted to the axle shaft 73 via.

Further, in the high speed mode H in the D range, the forward clutch C1 and the high clutch C2 are connected.

In this state, similarly to the above-mentioned case, the forward rotation that has been appropriately changed by the continuously variable transmission 30 is taken out from the output section 30a and input to the ring gear 21R of the single planetary gear W21.

Meanwhile, at the same time, the rotation of the input shaft 60 is transmitted to the sun gear 21S of the single planetary gear device 21 via the high clutch C2 and the high transfer device 80, thereby causing the ring gear 211? and the torque transmitted to the sun gear 21S are combined and output from the carrier 21C.

At this time, the sun gear 215 is equipped with a transfer device 8.
Since the rotation against the reaction force is transmitted through the transfer device 80, a predetermined positive torque is transmitted through the transfer device 80 without causing torque circulation.

Then, the combined torque from the toyaria 21C is transmitted to the axle shaft 73 via the reduction gear device 71 and the differential gear device 72.

Next, select low speed mode in S range and high speed mode +
(The operating state of each element is almost the same as that in the D range, but in the low speed mode of the D range mentioned above, it is in a free state when reverse torque is applied (during engine braking) based on the one-way clutch F. The low-coast tom reverse brake 81 operates in addition to the row one-way clutch F in the low speed mode of the S range, and transmits power even when reverse torque is applied.

Furthermore, in the R range, the low coast & reverse brake 81 and the reverse brake B2 are operated. In this state, in the dual planetary gear device 91, the ring gear 9LI? is fixed, the rotation of the input shaft 60 is inputted to the continuously variable transmission 30 as rotation in the opposite direction from the shaft 791C. On the other hand, based on the operation of the low-coast tom reverse brake 81, the single planetary gear device 2
One sun gear 21S is fixed, and therefore, reverse rotation from the continuously variable transmission 30 is decelerated in the single planetary gear device 21 and taken out to the output member 70.

Next, the functions of the control system for a vehicle automatic transmission will be explained with reference to FIG.

The control device U for a vehicle automatic transmission includes an electronic control device 120 including a microcomputer, a hydraulic control device 150,
It is also equipped with an external signal device consisting of various sensors, operating means, and a display device, and various actuators.

The electronic control unit 120 stores predetermined patterns such as best fuel consumption characteristics, maximum power characteristics, engine brake control, L-H switching control, etc., performs predetermined calculations, displays a display device 173, which will be described later, Driver 177, 178.17
9 and the hydraulic related device 151 of the hydraulic control device 150.

In addition, the external signal device includes a throttle opening sensor 161,
A primary pulley rotation speed sensor 165, a secondary pulley rotation speed sensor 166, a vehicle speed sensor 167, and a motor rotation signal sensor 1 are arranged in the continuously variable transmission 1 section.
69, a fund brake signal sensor 170 disposed in the driver's seat, a shift position sensor 171 that detects the selected position of the shift lever, and a pattern i! in which the driver selects and operates various patterns such as economy, power, etc. Sawa device 1
72, various display devices 173, etc.

The actuator includes a fluid coupling 11 and a lock-up clutch 12 disposed in the input device IO, a low-coast tom reverse brake B1, a forward clutch C1, a high clutch C2 and a reverse brake disposed in the auxiliary transmission 40. It has 2 km. The actuator further includes a C shift motor 101 that controls the speed of the continuously variable transmission 30 via a driver 177;
v↑It has a brake 180 that holds the speed change motor 101 in the speed change position, and also has a brake 153 that holds the L-H switching motor 152.33 and the L-H switching motor 152 in the switching position via the driver 178. The forward/reverse switching motor 154 via the driver 179 and the brake that holds the forward/reverse switching motor 154 in the switching position! 55 years old.

Next, the operation of the electronic control device 120 will be explained along the control block diagram of FIG. 5.

The operating limit (stroke end) of the continuously variable transmission M3o is detected by the rotation signal from the motor rotation signal sensor 169 and the alarm signal from the driver's alarm signal sensor 176, and the throttle opening is detected by the signal from the throttle opening sensor 161. (θ) and its rate of change is detected by taking into account the soft timer.

In addition, the primary pulley rotation speed <N,>t secondary pulley rotation speed (N,) is detected by the t= sign of the primary pulley rotation speed sensor 165 and the secondary pulley rotation speed sensor 166, respectively, and the vehicle speed sensor 1
The vehicle speed is detected by the signal from 67.

Also, patterns such as economy mode, power mode, etc. are detected by the signal from the pattern selection device 172, and furthermore, the pattern is detected by the signal from the shift position sensor 171.
, R, N, D, SH, 5L17) and detects the change in the shift position, and also detects the brake operating state based on the signal from the foot brake sensor 170.

Then, based on the throttle opening degree and its rate of change, the detected shift position value, and the detected pattern value, the acceleration request judgment unit 200 makes a predetermined judgment, and also based on the primary pulley rotation speed and the secondary pulley rotation speed, the current belt The ratio calculation unit 201 calculates the current torque ratio (hereinafter referred to as "current belt ratio") T of the continuously variable transmission 30.

Further, based on the current belt ratio value from the current belt ratio calculation section 201 and the current low speed or high speed mode state signal from the H-L3jA swamp determination section 203, which will be described later, the current system ratio calculation section 202 calculates the current stepless speed. A torque ratio (hereinafter referred to as "current system ratio") a as the shift Ill is calculated. On the other hand, based on the signal from the acceleration request determination unit 200, the pattern detection value, and the shift position detection value,
The best fuel efficiency/maximum power determining unit 205 determines whether to control according to the best fuel efficiency characteristic or the maximum power characteristic. Then, the best fuel efficiency/maximum power determination section 20
Based on the signal from 5, throttle opening, engine speed and vehicle speed, and brake detection signal, the target system
The lower limit calculation unit 206 calculates upper and lower limit values a0.1 and a"11. of the target torque ratio of the entire transmission (hereinafter referred to as "target system ratio").

Further, based on the signal from the upper/lower limit calculation unit 206, the target belt ratio calculation unit 207 calculates a target torque ratio (hereinafter referred to as “target belt ratio”) in the low speed mode of the continuously variable transmission 30.
Say. ) of T11. And the target belt ratio T″8 in the high speed mode is calculated.

Further, based on the vehicle speed and the signal from the current belt ratio calculation section 201, the low speed downshift check section 20B controls the gear shift of the continuously variable transmission 30 depending on the extremely sluggish running state, the sluggish running state, and the normal running state. .

Then, a signal from the acceleration request determination section 200, a detected throttle opening value, a signal from the current belt ratio calculation section 201, a signal from the current system ratio calculation section 202, a detected primary pulley rotation value, and a secondary pulley rotation value. Based on the detected value, the signal from the best fuel efficiency/maximum power determining section 205, the signal from the target system ratio upper/lower limit value calculating section 206, and the signal from the target belt ratio calculating section 207, the H-L selection determining section 203 determines the current state. Is it better to maintain the mode and achieve the target system ratio a''' only by changing the speed of the continuously variable transmission 30, or to change the mode (HL or L→H) to achieve the target system ratio a°? Decide which is better.

Furthermore, in addition to the high speed mode H or low speed mode L from the H-L selection determination unit 203, the stroke end detection value,
Based on signals from the acceleration request determination section 200, the current belt ratio calculation section 201, the target belt ratio calculation section 207, the target system ratio upper/lower limit value calculation section 206, and the low speed downshift navigation section 208, the CVT gear shift motor In the predetermined mode determined by the control signal generation unit 210-L selection determination unit 203, the upper and lower limits of the target system ratio a “6M1i
A predetermined rotation signal is output to the driver 177 so as to enter +a"1fi, and the CVT transmission motor 101 is rotated to control the continuously variable transmission 30.

Also, throttle opening detection values, P, R, N, D.

Based on the SH, SL detection values and the shift position change detection value, the forward/reverse switching motor control signal generator 211 generates a predetermined signal to the driver 179, and the forward/reverse switching motor 15
4 to control the forward/reverse switching device 90. and,
When the L-H switching motor control signal generation section 212 determines switching to the low speed and high speed modes based on the signal from the H-L selection charge cutting section 203, the shift position, and the throttle opening detection value, a switching signal is generated. and rotates the l-H switching motor 152 to perform the switching.

Next, the operation of the control device for a vehicle automatic transmission will be explained with reference to FIG.

Step ■ Read the detected values from each sensor as digital values.

Step (2) Calculate the current heald ratio T based on the primary pulley rotation speed Np and the secondary pulley rotation speed N. Here, T,=Np/N.

Step■ Step to calculate the current system ratio from the current mode (L mode or H mode) and current belt ratio■
Check the downshift at low speed based on the vehicle speed and the vehicle's extremely low speed, low speed, and normal driving conditions.

Step ■ Calculate the target system upper and lower limits from the throttle closing degree θ, driving mode (power mode or economy mode), brake signal, and vehicle speed detection value.

Step ■ Based on acceleration request, throttle opening, current belt ratio, primary pulley rotation speed N, , secondary pulley rotation 1iN, , current system ratio, driving mode, target system ratio, target heald ratio, auxiliary transmission 40 It is determined whether to set the mode to low speed mode or high speed mode.

Step ■ Based on the mode, acceleration request, current belt ratio, current system ratio, target torque ratio, target system ratio, etc. determined by the H-L selection judgment unit 203, the current system ratio is within the upper/lower limits of the target system. The shifting direction and shifting speed of the continuously variable transmission device 30 are determined as shown in FIG.

Step (2) A decision is made between the N range and the R range depending on conditions such as the shift position and throttle opening, and the forward/reverse switching motor 154 is controlled.

Step 7: The L-) rfj'JIA motor 152 is controlled by the mode switching signal, throttle opening, and position position signals from the H-ml flow determining section 203.

Here, processing for performing a downshift check at low speeds to prevent erroneous gear shifting will be described in detail.

(II speed downshift synchronization) Different processes are performed depending on the traveling speed of the vehicle. That is, the speed of the vehicle is changed to the primary pulley rotation speed N or the secondary pulley rotation speed N.

extremely low speed driving range (for example, vehicle speed <5 km/h), primary pulley rotation speed N, and secondary pulley rotation speed N, where it is impossible to accurately detect.

cannot be detected accurately, but the target torque ratio T0
is T□8 (for example, 5km/h <
The vehicle is divided into three regions: V < 1oIao/h) and other normal driving regions (for example, vehicle speed of lokm/h or more), and the speed change of the continuously variable transmission 30 is made different in each region.

FIG. 6 is a flowchart of processing operations for performing a downshift check at low speeds.

Step ■ Determine whether the vehicle is in the low speed range or extremely low speed.

■〈β The time is considered to be the extremely low speed driving region, β＜■＜T The time is considered to be the low speed driving region, γku■ The time is considered to be the normal driving range.

Steps ~■ When the vehicle is in the low speed range and the shift prohibition flag of the continuously variable transmission 30 is reset (A=0), the primary pulley rotation speed N and the secondary pulley rotation speed N are , the torque ratio Ti obtained from
(= Nr / Ns) and mechanically set limit torque ratio T. , 8.

If T, ≧Tam, it is assumed that the endless belt 33 has reached the underdrive side, and the count value B is incremented (B+
1-B).

Steps - - Compare the count value B and the comparison set value δ, and if B>δ, set the shift prohibition flag of the continuously variable transmission 30 (A=1).

Step (2) If the vehicle is in the extremely low speed driving area or the normal driving area, reset the shift prohibition flag (A=O).

Step ■ Torque ratio Ta (= NP / N3)
Compare with the limit torque ratio T, □.

If Ta < T, □, it is determined that the endless belt 33 is on the overdrive side and the count value B is cleared.

FIG. 7 is a flowchart of another processing operation for performing a downshift check at low speeds, and FIG. 8 is a diagram showing the relationship between vehicle speed and comparison set value δ.

Step ■ Determine whether the vehicle is in the low speed range or extremely low speed.

vku β The time is considered to be the extremely low speed driving region, β<V<γ The time is considered to be the low speed driving region, γ〈V The time is considered to be the normal driving range.

Steps ~■ When the vehicle is in a low speed range and the shift prohibition flag of the continuously variable transmission 30 is reset (A=0), calculate from the primary pulley rotation speed N and the secondary pulley rotation speed N. torque ratio T, l(
=Nr/Ns) is calculated and compared with the mechanically set limit torque ratio T,1.

If T8≧T 11 a M, it is assumed that the endless belt 33 has reached the underdrive side, and the count value B is incremented (B+
1-+B). Then, a comparison set value δm to be compared with the count value B is calculated from the current vehicle speed V, as shown in FIG.

Steps ■～■ Compare the count value B and the set value δ, and find that B>δ.

If so, the shift prohibition flag of the continuously variable transmission 30 is set (A=1).

Steps ■~■ If the vehicle is in the extremely low speed driving area or the normal driving area, reset the shift prohibition flag (A=0
) and clears the count value B.

Subsequently, after the low speed downshift check is performed, the continuously variable transmission 30 is controlled as follows depending on the presence or absence of the shift prohibition flag.

FIG. 9 is an operation flowchart for controlling the speed change of the continuously variable transmission 30.

Step ■ Determine whether the vehicle is in the low speed range or extremely low speed.

Step ■ If the vehicle is running at an extremely low speed and the vehicle speed ■ is v and β, a stop signal is output and the CV of the continuously variable transmission 30 is
The T-shift motor 101 is stopped.

Step ■ Even if the vehicle is in a low speed running state or a normal running state and ■〉β, if the shift prohibition flag of the continuously variable transmission 30 is set (A-1), a stop signal is similarly output. Then, the CVT speed change motor 101 of the continuously variable transmission 30 is stopped.

Step ■ The vehicle is in a low-speed driving state or a normal driving state, ■〉β, and the shift prohibition flag is not set (A=0
), it is determined whether the current system ratio a2 is within the range of the target system specific gravity/lower limit value a''aaM+a''aia.

If a %ia < a P < a ” maw, a stop signal is similarly output and the CVT of the continuously variable transmission 30 is activated.
The speed change motor 101 is stopped.

Steps ① to ② Determine the target torque ratio T1 depending on whether the current mode is high speed mode or low speed mode.

Step ■ ~ [Phase] Compare the target torque ratio T0 and the current torque ratio T, and if T"> TP, output a downshift signal; if T"<TP, output a downshift signal. Output.

Step ■ Calculate the shift speed according to the difference between the target input rotation speed and the current input rotation speed.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an operation flow diagram of a control device for a vehicle automatic transmission showing an embodiment of the present invention, FIG. 2 is a schematic diagram of the vehicle automatic transmission, and FIG. 3 is a diagram showing various positions of the vehicle automatic transmission. A diagram showing the operation of each element, Figure 4 is a control system function diagram of a vehicle automatic transmission, Figure 5 is a control block diagram of a vehicle automatic transmission, and Figure 6 is for downshifting at low speeds. Fig. 7 is a flowchart of other processing operations for performing a downshift check at low speeds, Fig. 8 is a diagram showing the relationship between vehicle speed and comparative setting values, and Fig. 9 is a diagram of the relationship between the vehicle speed and comparative setting values. FIG. 6 is an operation flow diagram for controlling the speed change. DESCRIPTION OF SYMBOLS 1... Continuously variable transmission, 10... Input device, 11...
Fluid coupling, 12...Lock-up clutch, 20...
-Low and high speed mode switching device, 22...Mode switching engagement device, 30...Continuously variable transmission, 31...Primary...
Pulley, 32... Secondary pulley, 33... Endless belt, 40... Auxiliary transmission, 60... Human power shaft,
70... Output member, 71... Reduction gear device, 72...
... Differential gear device, 80 ... Transfer device, 9
0... Forward/forward switching device, 101... CVT shift moke, 120... Electronic control device, 150... Hydraulic control device, 152... L-H switching motor, 154...
・Motor for forward/backward switching, 177, 178.179...
driver. Patent applicant: Aisin AW Co., Ltd. Agent: Patent attorney Mamoru Shimizu (1 other person) Figure 1 Figure 8 Figure S. VoVt ・ /4 Vr.

Claims (2)

[Claims] (1) By extending an endless belt with a V-shaped or trapezoidal cross section between two variable pulleys and changing the radial position where the endless belt contacts each variable pulley,
A control device for an automatic transmission for a vehicle that continuously converts and outputs the engine rotational speed transmitted through a fluid transmission device includes means for detecting vehicle speed, and a means for detecting vehicle speed to change the running state of the vehicle to an extremely low speed. Means for dividing into a driving area, a low-speed driving area, and a normal driving area, and continuously variable transmission when the driving condition is in the extremely low-speed driving area, or when the driving condition is in the low-speed driving area and the torque ratio is on the underdrive side. 1. A control device for an automatic transmission for a vehicle, comprising means for stopping gear shifting of the device. (2) Two variable pulleys consisting of a fixed flange and a movable flange whose relative positions can be changed by an electric motor are provided facing each other, and an endless belt with a V-shaped or trapezoidal cross section is stretched between the two variable pulleys. A control device for a vehicle automatic transmission that continuously converts and outputs the engine rotation speed transmitted via a fluid transmission device by changing the radial position where an endless belt contacts each variable pulley. means for detecting vehicle speed; means for dividing the running state of the vehicle into three regions, ie, a very low speed driving region, a low speed driving region, and a normal driving region, according to the vehicle speed; 1. A control device for an automatic transmission for a vehicle, comprising means for stopping shifting of a continuously variable transmission when the driving state is in a low-speed driving region and the torque ratio is on the underdrive side.