JPH0321781B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reduction ratio control method for a continuously variable automatic transmission for a vehicle using a V-belt type continuously variable transmission.

[Prior Art] A V-belt type non-contact pulley consists of an input pulley and an output pulley, which are provided on the input shaft and output shaft, respectively, and whose effective diameters are increased or decreased by a hydraulic servo, and a V-belt that transmits power between these input and output pulleys. A continuously variable automatic transmission for a vehicle using a step transmission is suitably used as a continuously variable automatic transmission for a vehicle such as an automobile in combination with a fluid coupling such as a torque converter or a fluid coupling and a forward/reverse switching mechanism. In this type of continuously variable automatic transmission for vehicles, the manual valve is set to the drive (D) range or low (L) range during normal driving or engine braking, depending on vehicle operating conditions such as vehicle speed and throttle opening. Accordingly, for example, an input pulley rotation speed control target rotation speed that provides the best fuel efficiency is set in advance, and control is performed so that the actual input pulley rotation speed matches the set target rotation speed.

On the other hand, control devices for continuously variable automatic transmissions for vehicles are required to prevent a shock when restarting by rapidly returning the V-belt to the maximum deceleration state, for example, in the event of a sudden stop. For example, the diameter of the hydraulic oil supply passage to the hydraulic servo of the input and output pulleys is generally set large.

[Problems to be Solved by the Invention] By the way, when controlling the actual input pulley rotation speed to match the target rotation speed as described above, the actual input pulley rotation speed is close to the input pulley control target rotation speed. In some cases, it is necessary to achieve a smooth shift with good responsiveness by realizing a minute shift, and when the difference between the actual input pulley rotation speed and the input pulley control target rotation speed is large, a rapid shift is realized. That is, it is necessary to adjust the reduction ratio change speed at which the reduction ratio is changed depending on the magnitude of the difference between the actual input pulley rotation speed and the input pulley control target rotation speed.

However, since the diameter of the hydraulic oil supply passage to the hydraulic servo of the input and output pulleys is set large, fluctuations in oil pressure become large during speed change control. Therefore, when performing minute shift control as described above, a problem arises in that shift shock is likely to occur.

The present invention has been made in view of such problems, and its purpose is to adjust the reduction ratio changing speed according to the magnitude of the difference between the actual input pulley rotation speed and the input pulley control target rotation speed. Therefore, it is an object of the present invention to provide a reduction ratio control method for a continuously variable automatic transmission for a vehicle, which can perform smooth speed change control with excellent responsiveness.

Another object of the present invention is to enable minute shift control, prevent shift shock during shift control, and obtain sufficient shift speed even during sudden shifts. Moreover, it is an object of the present invention to provide a reduction ratio control method for a continuously variable automatic transmission for a vehicle, which can prevent a shift shock at the time of starting.

[Means for Solving the Problems] In order to achieve this object, the present invention provides an input pulley and an output pulley that are provided on an input shaft and an output shaft, respectively, and whose effective diameters are increased or decreased by a hydraulic servo, and these input pulleys. and a V-belt for transmitting power between the output pulleys, an electronic control circuit comprising means for detecting vehicle running conditions and logic means for outputting in response to input from the detecting means, and a V-belt for transmitting power between the input pulley or the output pulley. It consists of a reduction ratio control means for supplying and discharging hydraulic oil, an upshift electromagnetic solenoid means and a downshift electromagnetic solenoid means that control the reduction ratio control means, and the upshift electromagnetic solenoid means or downshift is controlled by the output of the electronic control circuit. By controlling the electromagnetic solenoid means for controlling the supply and discharge of hydraulic oil to the hydraulic servo of the input pulley and output pulley, the reduction ratio of the V-belt type continuously variable automatic transmission is controlled according to the vehicle running conditions. In a control method for a continuously variable automatic transmission for a vehicle, the control method includes a hydraulic control circuit including a reduction ratio control mechanism that changes the input pulley control target rotation speed and the input pulley control target rotation speed set in advance according to vehicle running conditions by the electronic control circuit When the rotational speed difference with the actual input pulley rotational speed is more than the set value, the upshift electromagnetic solenoid means or the downshift electromagnetic solenoid means is operated continuously, and when the rotational speed difference is less than the set value, the electromagnetic solenoid means for upshifting or downshifting is operated continuously. The present invention is characterized in that duty control is performed in which the operating time of the upshift electromagnetic solenoid means or the downshift electromagnetic solenoid means changes depending on the magnitude of the difference.

[Operation and Effects of the Invention] According to the reduction ratio control method for a continuously variable automatic transmission for a vehicle of the present invention configured as described above, the input pulley control target rotation speed set in advance and the actual When the rotational speed difference between the input pulley rotational speed and the input pulley rotational speed is more than the set value, the upshift electromagnetic solenoid means or the downshift electromagnetic solenoid means is operated continuously, and when the rotational speed difference is less than the set value, the difference is Since duty control is performed in which the operating time of the upshift electromagnetic solenoid means or the downshift electromagnetic solenoid means changes depending on the magnitude, The reduction ratio changing speed can be adjusted by using the following steps, and smooth speed change control with excellent responsiveness can be performed.

In addition, this speed change control makes it possible to perform minute speed change control, so even if the diameter of the hydraulic oil supply passage to the hydraulic servo of the input and output pulleys is set large, the hydraulic pressure during speed change control will be reduced. Fluctuations can be reduced, and shift shocks can be prevented during minute shift control. On the other hand, by setting the diameter of the hydraulic oil supply passage to be large, the V-belt can be quickly returned to the maximum deceleration state in the event of a sudden stop, thereby preventing a shock when restarting.

[Example] Next, the present invention will be explained based on an example shown in the drawings.

FIG. 1 shows a continuously variable automatic transmission for a vehicle.

100 has an open fastening surface 100A with the engine and a fluid coupling room 110 where fluid couplings such as fluid couplings and torque converters are stored, and a fluid coupling room 110 with an open side opposite to the engine where differential gears are stored and the fluid coupling room 110 is opened. A differential room 120 that supports one output shaft of the differential gear, and an idler gear room 13 that is similarly open on the side opposite to the engine, houses the idler gear, and supports one of the shafts of the idler gear.
0, a transmission room 210 having an opening on the engine side and housing a V-belt continuously variable transmission; The torque converter case consists of a differential room 220 that supports the other output shaft of the allencial, and an idler gear room 230 that covers the side opposite to the engine side of the idler gear room 130 of the torque converter case. The transmission case is bolted to the side 100B opposite to the engine, and forms the outer shell (case) of the continuously variable automatic transmission for a vehicle together with the torque converter case and a center case described later. 300
is a center case that pivotally supports the transmission shaft between the fluid coupling and the transmission, and in this embodiment, when housed in the transmission case, the side 1 of the torque converter case opposite to the engine
It has a center case structure that is bolted to 00B. In this embodiment, the automatic transmission includes a known fluid coupling 40 disposed within the torque converter case 100 and connected to the output shaft of the engine.
0 and a transmission provided within a transmission case 200. The input shaft 510 of the transmission has a hollow shaft center, and the hollow portion 511 serves as an oil supply/discharge path for hydraulic oil and lubricating oil for the hydraulic servo, and the input shaft 510 is connected to the fluid coupling 400.
An output shaft 550 is disposed coaxially with the input shaft 51, the shaft center is hollow, and the hollow part 511 is used as an oil supply/discharge path for hydraulic oil of a hydraulic servo.
V-belt continuously variable transmission 50 arranged in parallel with 0
0, a planetary gear transmission mechanism 600 disposed between the input shaft 510 of the V-belt continuously variable transmission and the output shaft of the fluid coupling; the input shaft 510 and the output shaft of the V-belt continuously variable transmission 500; 550 and an output shaft 710 connected to an axle, and an input large gear 720 of the differential 700 and the output shaft of the V-belt continuously variable transmission 500. 550
is inserted between the output gear 590 of a V-belt type continuously variable transmission provided at the end of the engine, one end is supported by the torque converter case parallel to the output shaft 550, and the other end is supported by the inner shaft. An idler gear shaft 801 supported by a center case 300, and an input gear 802 and an output gear 803 provided on the idler gear shaft.
It consists of an idler gear 800 consisting of.

The V-belt continuously variable transmission 500 and the planetary gear transmission mechanism 600 change the reduction ratio, forward movement,
Predetermined controls such as reversing are performed.

Reference numeral 104 denotes an oil pump cover which is fastened to the engine side (fluid coupling side) wall of the center case and houses therein an oil pump 106 driven by a hollow shaft 410 integrated with the fluid coupling 400. It is.

Output shaft 420 of fluid coupling 400
is rotatably supported by a sleeve 310 fitted in the center of the center case 300 via a metal bearing 320, and has a hub 440 of a lock-up clutch 430 and a hub 460 of a fluid coupling turbine 450 at the end on the engine side. are spline-fitted, and the other end is enlarged in diameter in a stepped manner, and the large diameter portion is connected to the input shaft 601 of the planetary gear transmission mechanism 600.
and is supported by the center case 300 via a bearing 330. The output shaft 420 of the fluid coupling and the input shaft 601 of the planetary gear transmission mechanism are formed hollow, and the hollow portion is provided with an oil passage 421 and a plug 423 is fitted therein.
Furthermore, the input shaft 510 of the V-belt type continuously variable transmission
The engine side end of the sleeve 422, which is fixed to the engine, is rotatably fitted.

The planetary gear transmission mechanism 600 includes an input shaft 6 that is integrated with the output shaft 420 of the fluid coupling 400.
01, a carrier 620 connected to a fixed flange of a V-belt continuously variable transmission (to be described later) via a multi-disc clutch 630, and a ring engaged with the center case 300 via a multi-disc brake 650. A gear 660, a sun gear 670 provided on the outer periphery of the output shaft 610 of a planetary gear transmission mechanism that is integrally formed with the input shaft 510 of the V-belt continuously variable transmission, and a sun gear 670 that is pivotally supported by the carrier 620, and a sun gear 670 and a ring gear. 660, a hydraulic servo 680 formed on the wall of the center case 300 for operating the multi-disc brake 650, and a hydraulic servo 690 formed on the fixed flange wall for operating the multi-disc clutch 630. Become.

The V-belt continuously variable transmission 500 has an input shaft 510 that is integrated with an output shaft 610 of the planetary gear transmission mechanism 600.
A fixed flange 520A integrally formed with the fixed flange 520A and a hydraulic servo 530
An input pulley 520 consisting of a movable flange 520B driven in the 0A direction, a fixed flange 560A formed integrally with the output shaft 550 of the V-belt continuously variable transmission, and the hydraulic servo 570 driven in the fixed flange 560A direction. The output pulley 560 includes a movable flange 560B, and a V-belt 580 transmits power between the input pulley 520 and the output pulley 560.

The input shaft 510 of the V-belt type continuously variable transmission has an engine side end 510A, which serves as an output shaft 610 of the planetary gear transmission mechanism, supported by the input shaft 601 of the planetary gear transmission mechanism via a bearing 340,
It is supported by the center case 300 via the input shaft 601 and the bearing 330, and the other end 5
10B is supported by a side wall 250 of the transmission case opposite to the engine via a bearing 350, and furthermore, its tip end surface 510C is supported by the side wall 250 of the transmission case.
Needle (roller) on the lid 260 fastened to 0
They are brought into contact via a bearing 270.

The sleeve 422 is fitted into the hollow part 511 formed at the center of the input shaft 510 of the V-belt continuously variable transmission on the side of the engine, and the part 511A on the opposite side from the engine is connected to the center case 300 and the oil passage 301.
The oil pressure supplied from the oil passage 421 is transferred to an oil passage 513 formed at the base of the fixed flange 520A.
is used as an oil path for supplying hydraulic pressure to the hydraulic servo 690 through the oil passage, and its tip 511B is configured such that the tip closes the hole 250A formed in the side wall 250 of the transmission case at a portion corresponding to the input shaft 510. Pipe-shaped protrusion 261 of the attached lid 260
Pressure oil is supplied through the protrusion 261 of the lid 260 from an oil passage 514 formed in the transmission case 200 including the lid 260 and whose entire space communicates with the hydraulic control device. 5
It acts as an oil passage for supplying oil to 30.

The output gear 590 is integrally formed with a hollow support shaft 591, and the support shaft 591 has an engine side end 591A.
A roller bearing 59 forms one fulcrum.
2, and the other end 591B is supported by a roller bearing 593.
The output gear 590 is supported by the center case 300 via the center case 300, and the engine side side 590A of the output gear 590 is brought into contact with the side wall of the torque converter case via a needle bearing 594 forming an intermediate fulcrum. The side surface 590B is connected to the center case 3 via the needle bearing 595.
Inner spline 596 is in contact with the side surface of
is formed.

The output shaft 550 of the V-belt type continuously variable transmission has an outer spline 550A formed at the end near the engine that fits into the inner spline 596 formed on the support shaft 591 of the output gear, and the output gear The other end 550B is supported by the center case 300 via a support shaft 591, and the other end 550B is connected to the side wall 25 of the transmission case opposite to the engine via a ball bearing 920 forming the other support.
It is supported by 0.

A sensing valve body 552 is fitted in the middle part of an oil passage 551 formed at the center of the output shaft 550 of this V-belt type continuously variable transmission, and an engine side part 552A of the valve body 552 is connected to the transmission case. The hydraulic pressure supplied from the formed oil passage 140 that communicates with the hydraulic control device is an oil passage that is guided to the hydraulic servo 570, and a portion 552B of the valve body 552 on the side opposite to the engine has a tip that is connected to the side wall of the transmission case. The pipe-shaped protrusion 5 of the lid 553 is fitted with a lid so as to close the hole 250B formed in the corresponding part to the output shaft 550 of the lid 550.
54 and a transmission case, and a lid 55 fastened to the transmission case.
3 and a movable flange 56 from the hydraulic control device.
This is an oil passage 3 whose oil pressure is adjusted by a reduction ratio detection valve 50 shown in FIG. 2 for detecting the displacement position of 0B. In the reduction ratio detection valve 50, an engagement pin 51A attached to the right end of the detection rod 51 in the drawing is engaged with a step formed on the inner circumference of the movable flange 560B, and the reduction ratio detection valve 50 is operated by the displacement of the spool due to the displacement of the movable flange 560B. Adjust the oil pressure of oil line 3.

FIG. 2 shows a hydraulic control device for controlling the continuously variable automatic transmission for a vehicle shown in FIG. 21 is an oil sump;
20 is driven by an engine, and the oil sump 21
30 is a pressure regulating valve that adjusts the oil pressure of oil path 1 according to the input oil pressure and sets it as line pressure; 40 is a pressure regulating valve that adjusts the line pressure supplied from oil path 1; The pressure is regulated according to the throttle opening and output as the first throttle pressure from the oil passage.
a throttle valve 5 that outputs the reduction ratio pressure output from the reduction ratio detection valve 50, which is supplied from the oil passage 3 via the orifice 22, as a second throttle pressure from the oil passage 3a when the throttle opening is equal to or greater than a set value Θ1;
0 is the reduction mode that adjusts the hydraulic pressure of the oil passage 3 communicating with the oil passage 1 via the orifice 23 in accordance with the displacement amount of the movable flange 560B of the output pulley of the V-belt type continuously variable transmission shown in FIG. The ratio detection valve 60 communicates with the oil passage 1 via the orifice 24, regulates the oil pressure of the oil passage 4 through which excess oil from the pressure regulating valve 30 is discharged, and uses the surplus oil passage as lubricating oil from the oil passage 5. A second pressure regulating valve 65 that supplies lubrication required parts of the automatic transmission is a manual valve 70 that is operated by a shift lever provided at the driver's seat and distributes the line pressure of the oil passage 1 according to the driver's operation. 80 is a lock-up control mechanism that supplies hydraulic pressure in the oil passage 4 to the fluid coupling 400 in response to an input, and controls engagement and release of the lock-up clutch 430; Reduction ratio (torque ratio) control mechanism of a V-belt type continuously variable transmission 500, which outputs the hydraulic pressure of the oil path 1a connected to the oil path 1b from the oil path 1b to the hydraulic servo 530 of the input pulley.
0 is provided in the oil passage 1c that communicates with the oil passage 1 when the manual valve 65 is shifted to the L range, and regulates the line pressure and sets it as the low modulator pressure to the oil passage 2.
12 is a relief valve provided in the oil cooler oil passage 11, 25A
26 is a relief valve provided in the oil passage 1, and 26 is a hydraulic servo 6 of the multi-disc brake of the planetary gear transmission mechanism 300.
80 is a flow control valve with a check valve provided in the line pressure supply oil passage 6; 27 is a planetary gear transmission mechanism 30;
This is a flow control valve with a check valve installed in the line pressure supply oil passage 7 to the hydraulic servo 690 of the multi-disc clutch.

The hydraulic pressure adjustment device is composed of the pressure regulating valve 30, the throttle valve 40, and the reduction ratio detection valve 50.

The reduction ratio detection valve 50 includes a detection rod 51 having an engagement pin 51A fixed to one end that engages with a movable flange 560B of an output pulley of a V-belt type continuously variable transmission, and a detection rod 51 having a spring 52 mounted on the other end; The detection rod 51
and a spool 54 having lands 54A and 54B arranged in series via a spring 53, a port 55 communicating with the oil passage 3, a drain port 56,
Provided at port 55 and port 55 and land 54A
An oil passage 5 communicating between the oil chamber 54a and the oil chamber 54B
7, and generates a hydraulic pressure Pi as a reduction specific pressure in the oil passage 3 as shown in FIG. 3 in accordance with the displacement of the movable flange 560B.

The throttle valve 40 includes a throttle plunger 42 that is displaced by contacting a throttle cam 41 linked to an accelerator pedal at the driver's seat, and a spool 44 that is connected in series with the throttle plunger 42 via a spring 43. Plunger 42 and spool 44 as Θ increases.
is displaced to the right in the figure. The plunger 42 connects the oil passage 3 and the oil passage 3a when the rotation angle of the throttle cam 41 and the hydraulic throttle opening Θ of the oil passage 2 fed back to the land 42a exceed a set value Θ1 (Θ>Θ1). A second throttle pressure equal to the reduction ratio pressure is generated in the oil passage 3a, and Θ<
When Θ1, the oil passage 4 provided in the plunger 42
2a from the drain port 40a to the oil passage 3a
The hydraulic pressure is discharged to generate a second throttle pressure Pj in the oil passage 3a as shown in FIG. The movement of the throttle cam is transmitted to the spool 44 via the spring 43, and the oil passage 2 is fed back to the land 44a via the throttle opening and the orifice 45.
The throttle pressure Pth generated in the oil passage 2 is regulated by changing the communication area between the oil passage 1 and the oil passage 2 as shown in FIGS. 5 and 6.

The pressure regulating valve 30 has a spring 31 on its back on one side (left side in the figure), and lands 32A, 32B, 32C.
a spool 32 equipped with a spool 32; a first regulator plunger 33 disposed in series on the spool 32 and provided with a small-diameter land 33A and a large-diameter land 33B; It has a second regulator plunger 34 arranged therein, a port 34a communicating with the oil passage 1, a port 34b to which line pressure is fed back via an orifice 35, a drain port 34c, and excess oil being discharged to the oil passage 4. A drain port 34 drains leaked oil from between the land and the valve wall.
e, an input port 34f to which the reduction ratio pressure is input from the oil passage 3, an input port 34g to which the first throttle pressure is input from the oil passage 2, and an input port 34h to which the second throttle pressure is input from the oil passage 3a. Become.

The low modulator valve 10 outputs the low modulator pressure Plow shown in FIG. 7, which is independent of the throttle opening when the manual valve 65 is set to the L range. Here, neither the low modulator valve nor the throttle valve has a discharge pressure oil passage for pressure regulation.
The throttle valve Pth is configured to regulate the pressure by utilizing the fact that the pressure is constantly discharged from the reduction ratio control mechanism 80, and both of these valves are arranged in parallel. Therefore, in the L range, the larger hydraulic pressure of Plow and Pth is generated in the oil passage 2 as shown in FIG. Therefore, as shown in FIG. 9, the line pressure PL in the L range with a low throttle opening is higher than in the D range.

This pressure regulating valve 30 is configured to control a reduction ratio pressure input from a port 34f and applied to the second plunger 34, a first throttle pressure input from a port 34g and applied to the land 33B of the first plunger 33, and a first throttle pressure input from a port 34h and applied to the land 33B of the first plunger 33. The second throttle pressure is applied to the land 33A of the first plunger 33, and the second throttle pressure is applied to the land 33A of the spool from the port 34b, which is connected to the oil passage 1 via the spring 31 and the orifice 35.
The spool 32 is displaced by the line pressure fed back to the port 34 connected to the oil path 1.
a. Adjust the opening areas of the port 34d and drain port 34c that communicate with the oil passage 4 to increase or decrease the amount of pressure oil leaking from the oil passage 1 to obtain the line pressure PL shown in Figs. 9, 10, and 11. cause In L range, it is necessary to downshift to obtain strong engine braking. In a V-belt type continuously variable transmission, when downshifting, the oil path to the hydraulic servo 530 of the input pulley is connected to the exhaust pressure oil path, thereby draining the oil in the servo oil chamber and realizing downshifting. . However, in order to obtain strong engine braking, the primary sheave must be rotated at a high rotation speed, but the hydraulic pressure caused by the centrifugal force generated by this rotation may prevent oil drainage. Therefore, when a quick downshift is required, it is necessary to make the hydraulic pressure applied to the output pulley's hydraulic servo 570 higher than normal, which is particularly important when the throttle opening is low. Therefore, in the L range, the throttle pressure Pth is increased by the low modulator valve when the throttle opening Θ is small, and the line pressure PL is increased.
(Line pressure = hydraulic servo supply pressure of output pulley)
is increasing.

The manual valve 65 is a spool that is moved by a shift lever provided on the driver's seat and is set to each shift position of P (park), R (reverse), N (neutral), D (drive), and L (low). 66, and when set at each shift position, oil passage 1 or oil passage 2 communicates with oil passage 1c, oil passage 6, and oil passage 7 as shown in the table.

Table P R N D L Oilway 7 × × × △ △ Oilway 6 × 〇 × × × Oilway 1C - - △ △ 〇 In the table, 〇 indicates connection with oilway 1, △ indicates communication with oilway 2, - indicates blockage of the oil passage, and × indicates exhaust pressure. As shown in this table, in the R range, line pressure is supplied to the brake 680 of the planetary gear transmission mechanism, and in the D and L ranges, the throttle pressure (or low modulator pressure) of the oil passage 2 is supplied to the clutch 690, and switching between forward and reverse is performed. It will be done.

The second pressure regulating valve 60 has a spool 62 with a spring 61 on one side and lands 62A, 62B, and 62C.
land 62 through the spring load and orifice 63
It is displaced by the oil pressure applied to A to change the flow resistance of the oil passages 4 and 5 and the drain port 60A, thereby regulating the oil pressure of the oil passage 4 and supplying lubricating oil from the oil passage 5 to parts that require lubrication. Excess hydraulic oil is drained from the drain port 60A.

The reduction ratio control mechanism 80 includes a reduction ratio control valve 81, orifices 82 and 83, an upshift electromagnetic solenoid valve 84, and a downshift electromagnetic solenoid valve 85.

The reduction ratio control valve 81 has a first land 812A, a second land 812B, and a third land 812C, and a spring 811 is attached to one land 812C.
A spool 812 is installed behind the spool 812, side oil chambers 815 and 816 at both ends are supplied with throttle pressure or low modulator pressure from the oil passage 2 through orifices 82 and 83, respectively, and an intermediate portion between land 812B and land 812C. Oil chamber 810, oil chamber 81
5 and the oil chamber 810, which communicates with the oil path 1 to which line pressure is supplied, and which connects the spool 8 and the oil chamber 810.
12, and an output port 818 that communicates with the hydraulic servo 530 of the input pulley 520 of the V-belt continuously variable transmission 500 via the oil path 1b. A drain port 814 that evacuates the oil chamber 819 according to the movement of the chamber 819 and the spool 812, and a drain port 813 that evacuates the oil chamber 810 and the oil chamber 815 according to the movement of the spool 812 are provided.

The electromagnetic solenoid valve 84 for upshifting and the electromagnetic solenoid valve 85 for downshifting are respectively attached to an oil chamber 815 and an oil chamber 816 of the reduction ratio control valve 81, and both are operated by the output of an electric control circuit to be described later. Chamber 815 and oil chamber 81
0 and the oil chamber 816 are evacuated.

The lockup control mechanism 70 includes a lockup control valve 71, an orifice 77, and an orifice 77.
and an electromagnetic solenoid valve 76 that controls the oil pressure of the oil passage 4a that communicates with the oil passage 4 via the oil passage 7.

The lock-up control valve 71 is located on one side (right side in the figure).
A spring 72 is installed behind the land 7 of the same diameter.
3A, 73B, and 73C, and a sleeve 75 that is provided in series with the spool 73, has a spring 74 on its back on the other side (left side in the figure), and has a diameter larger than the land of the spool 73,
Oil pressure P4 of the oil passage 4 applied to the land 73C via the input port 71A connected to the oil passage 4 from one side.
and the spring load Fs1 of the spring 72,
From the other side, the solenoid pressure Ps of the oil passage 4a controlled by the solenoid valve 76 is applied to the sleeve 75, or the oil pressure P8 of the oil passage 8 and the spring 74 is applied to the land 73A through the port 71D, which is applied to the release side of the lock-up clutch 430. Spring load due to
In response to Fs2, the spool 73 is displaced to control the communication between the oil passage 4 and the release side oil passage 8 or the engagement side oil passage 9 of the lock-up clutch 430. When the solenoid valve 76 is energized and turned on, the hydraulic pressure in the oil passage 4a is discharged, the spool 73 is fixed to the left in the figure, the oil passage 4 and the oil passage 9 are in communication, and the hydraulic oil is The fluid flows in the order of path 9 → lock up clutch 430 → oil path 8 → drain port 71C, and lock up clutch 430 is in an engaged state. When the solenoid valve 76 is de-energized and the valve port is closed (OFF), the oil pressure in the oil passage 4a is maintained, the spool 73 is fixed to the right in the figure, the oil passage 4 is in communication with the oil passage 8, and the hydraulic oil is flows in the order of oil passage 8 -> lock up clutch 430 -> oil passage 9 -> connecting oil passage 11 to the oil cooler.
0 is free.

FIG. 12 shows electronics for controlling the electromagnetic solenoid valve 76 of the lock-up clutch control mechanism 70, the upshift electromagnetic solenoid valve 84 and the downshift electromagnetic solenoid valve 85 of the reduction ratio control mechanism 80 in the hydraulic control system shown in FIG. Control device 9
0 configuration is shown.

91 is a shift lever switch that detects whether the shift lever is shifted to P, R, N, or L; 92 is a rotation detection sensor that detects the rotation speed of input pulley A; 93 is a vehicle speed sensor; 94 is an engine Throttle sensor that detects the throttle opening of 95 is ON when the throttle opening Θ is 0.
96 is a speed detection processing circuit that converts the output of the rotational speed sensor 92 into voltage, 97 is a vehicle speed detection circuit that converts the output of the vehicle speed sensor 93 into voltage, and 98 is a throttle sensor 94.
907 to 911 are input interfaces of each sensor, 912 is a central processing unit (CPU), 91 is a throttle opening detection processing circuit that converts the output of
3 is a read-only memory (ROM) 91 that stores programs for controlling the electromagnetic solenoid valves 76, 84, and 85 and data necessary for the control;
4 is a random access memory (RAM) that temporarily stores input data and parameters necessary for control; 915 is a clock; 916 is an output interface; 917 is a solenoid output driver that downshifts the output of the output interface 916; solenoid valve 85 for upshift, solenoid valve 84 for upshift solenoid, and shift control solenoid 74. Input interfaces 908 to 911 and CPU 912,
The ROM 913, RAM 914, and output interface 916 are communicated with each other by a data bus 918 and an address bus 919.

Next, the operation of the reduction ratio control mechanism 80 controlled by the electronic control device 90 will be explained with reference to FIGS. 13 to 23.

During normal driving, the continuously variable automatic transmission for vehicles controls the reduction ratio (torque ratio) of the V-belt type continuously variable transmission to achieve the best fuel efficiency at each throttle opening Θ by the electronic control unit 90, and the input So-called best fuel efficiency control is performed to determine the rotational speed N of the pulley.

The control of the reduction ratio control mechanism 80 is performed by increasing or decreasing the speed ratio between the input and output pulleys by comparing the best fuel economy input pulley rotation speed N with the actual input pulley rotation speed N. This is done by the action of two electromagnetic solenoid valves 84 and 85, and the actual input pulley rotation speed N is made to match the input pulley rotation speed for the best fuel efficiency. In other words, the best fuel economy engine output line (Figure 15) can be obtained from the equal engine fuel efficiency curve (Figure 13) and the equal horsepower curve (Figure 14). By combining the engine performance at each throttle opening Θ (FIG. 16), the best fuel economy engine speed (FIG. 17) at each throttle opening Θ is determined. The best fuel efficiency control can be achieved by controlling the gear ratio so that the best fuel economy engine speed is achieved for each throttle opening.

FIG. 18 shows an operation chart of the control circuit of the reduction ratio control mechanism 80 of the V-belt type continuously variable transmission. Input the shift lever shift position, input pulley rotation speed N, vehicle speed V, throttle opening Θ, and idling signal (idling switch ON signal), and turn on or off the upshift electromagnetic solenoid valve 84 and the downshift electromagnetic solenoid valve 85. By turning it off, the gear ratio is controlled.

The throttle opening Θ is determined by the throttle sensor 94.
After reading 921, the input pulley rotation speed and vehicle speed are read 922 using the input pulley rotation speed sensor 92 and vehicle speed sensor 93. Next, the idling signal of the idling switch 95 is read 923, and then the shift lever switch The shift position is read 924. After reading this information, the shift lever position is determined 925 by the shift lever switch 91, and the process proceeds to a subroutine 930 for P and N processing, a subroutine 940 for L and D processing, or a subroutine 960 for R processing. 19 and 20 show a broach chart of the control circuit shown in FIG. 18, and FIG. 21 shows a graph for explaining the operation.

B. When the shift lever is set to the P position or the N position, both the upshift electromagnetic solenoid valve 84 and the downshift electromagnetic solenoid valve 85 are activated by the subroutine 930 for P and N position processing shown in FIG. OFF (931),
The P or N state is stored in RAM 914 (932). This provides a neutral state for the input pulley 520.

(b) When the shift lever is set to the L position or the D position, according to the first reduction ratio control method for a vehicle automatic transmission, the upshift electromagnetic solenoid valve 84 and the downshift Shift electromagnetic solenoid valve 8
5 is controlled as shown in the flow chart shown in FIG.

If the brake is not pressed, the throttle is not fully closed, and the shift lever is in the D position, the best fuel efficiency control is performed. In this case, the best fuel efficiency control line shown in FIG. 17 is stored in the ROM 913 in the form of a table, the input pulley rotation speed for the throttle opening Θ is drawn from the table, and the input pulley rotation speed is used for input pulley control. Control is performed using the target rotation speed Nc. In other words, the actual input pulley rotation speed N
If is larger than the input pulley control target rotation speed Nc, the upshift electromagnetic solenoid valve 84 is turned on, if it is smaller than the number of control circuits, the downshift electromagnetic solenoid valve 85 is turned on, and if it is equal to the control rotation speed, both solenoid valves are turned on. Turn off.

First, it is determined whether the shift lever position is set to the "D" position or the "L" position, and the throttle opening Θ is determined from the D range table or L range table according to each setting position. Read the control target rotation speed Nc of the corresponding input pulley (941) and check the lag.
It is determined whether it is ON or OFF (952), and then the current actual input pulley rotation speed N and the control target rotation speed Nc are determined.
A determination is made as to whether or not the difference is greater than 0.

When N-Nc>0, it is determined whether or not the actual input pulley rotation speed N is larger than the control target rotation speed Nc plus a constant Nu for setting the duty control area during upshifting (943). conduct,
When NNc+Nu, area A in FIG. 21 is set so that the upshift electromagnetic solenoid valve 84 is turned on for a set time (for example, 0.5 seconds) (944),
Outputs the ON operation signal of the upshift electromagnetic solenoid valve 84 (945), and when N<Nc+Nu, the second
In area B) of Figure 1, the ON time tu of the upshift electromagnetic solenoid valve 84 is set as shown in equation 1 (946).

tu=a+b(N-Nc)...1 In equation 1, a and b are coefficients determined by the configuration of the continuously variable automatic transmission for the vehicle and the hydraulic control circuit. The example shown in FIG. 21 is an example in which coefficients a and b are constants, but a and b may also be functions of Nc or N.

Next, an output is output to turn on the upshift electromagnetic solenoid valve 84 for the set tu time. (945). At this time, the duty ratio is tu/Tu, where Tu is the cycle for turning the upshift electromagnetic solenoid valve 84 ON and OFF.

In determining the difference between the current actual input pulley rotation speed N and the control target rotation speed Nc (942), N-Nc
If it is 0, then control target rotation speed Nc and input pulley rotation speed set to give appropriate hysteresis.
It is determined whether the difference from No. is larger than the actual input pulley rotation speed N. When Nc-NoN (area C in FIG. 21), an output is made so that both the upshift electromagnetic solenoid valve 84 and the downshift electromagnetic solenoid valve 85 are turned OFF (948).

When Nc-No>N, it is determined whether the actual input pulley rotation speed N and Nc-No-Nd are larger or smaller (949). Here, Nd is a constant for setting the duty control region during downshifting, N<Nc−No−
When Nd (region E in Fig. 21), the downshift electromagnetic solenoid valve 85 is operated for a set time (for example,
Set to turn on continuously (0.5 seconds) (950)
Then, turn on the downshift electromagnetic solenoid valve 85.
Output the operating signal (951) (When N>Nc-No-Nd (area D in Fig. 21), set the ON time td of the downshift electromagnetic solenoid valve 85 as shown in equation 2. (952) td = C + d ( Nc-No-N)...2 sets Next, output to turn on the downshift electromagnetic solenoid valve 85 for the set tu time (951).

In Equation 2, c and d are coefficients determined by the configuration of the vehicle continuously variable automatic transmission and the hydraulic control circuit. Although the example in FIG. 21 is an example in which the coefficients c and d are constants, c and d may also be functions of Nc or N. At this time, the duty ratio is td/Td, where Td is the period of ON and OFF operation of the downshift electromagnetic solenoid valve 85.

Next, the operation of the reduction ratio control mechanism 80 will be explained with reference to FIG. 22.

When traveling at a constant speed, electromagnetic solenoid valves 84 and 8 are controlled by the output of the electric control circuit 90 as shown in FIG. 22A.
5 is turned off. As a result, the oil pressure Pd in the oil chamber 816 becomes the throttle pressure or low modulator pressure, and the oil pressure Pu in the oil chamber 815 also changes to the spool 81.
When 2 is on the right side in the figure, it is line pressure. Since the spool 812 has a pressing force P3 due to the spring load of the spring 811, the spool 812, which is moved to the left in the figure, is moved to the left and the oil chamber 815 is moved to the left.
communicates with the drain port 813 via the oil passage 2A and the oil chamber 810, and the pressure of Pu is discharged, so the spool 812 is moved to the right in the figure by the oil pressure Pd of the oil chamber 816. When spool 812 is moved to the right, drain port 813 is closed. Therefore, in this case, the spool 812 can be held in a more stable state by providing a flat plane (tapered surface) 812a at the edge of the drain port 813 of the land 812B of the spool 812.
12 can be maintained at an equilibrium point at an intermediate position as shown in FIG. 22A.

When the oil passage 1b is held at the equilibrium point at the intermediate position as shown in FIG. The line pressure causes it to be compressed via the V-belt 580, and as a result, it balances out with the hydraulic pressure of the hydraulic servo 570. Actually, since there is oil leakage in the oil passage 1b as well, the input pulley 520 is gradually expanded and the torque ratio T changes in the direction of increasing. Therefore, as shown in FIG. 22A, the spool 81
2 is in equilibrium, the drain port 8
Port 81 of land 812B of spool 812 so that 14 is closed and oil passage 1a is slightly open.
7-edge flat surface (tapered surface) 81
2b is provided to compensate for oil leakage in the oil passage 1b. Furthermore, by providing a flat surface (tapered surface) 812C at the edge of the drain port 814 of the land 812A, changes such as the rise of oil pressure changes in the oil passage 1b can be made smooth. In this case, the hydraulic pressure leaks only from the pressure oil discharged from the drain port 813 via the orifice 82, and there is only one leakage location.

During UP-SHIFT, the up-shift electromagnetic solenoid valve 84 is turned ON by the output of the electric control circuit 90 as shown in Fig. 22C.
be done. As a result, the pressure in the oil chamber 815 is exhausted, and the spool 812 is moved to the right in the drawing, the spring 811 is compressed, and the spool 812 is set to the right end in the drawing.

In this state, the line pressure of oil passage 1a is
8 to the oil path 1b, the oil pressure of the hydraulic servo 530 increases, the input pulley 520 operates in the direction of closing, and the torque ratio T decreases. Therefore, by controlling the ON time of the solenoid valve 84 as necessary, the upshift is performed by reducing the torque ratio by a desired amount.

At the time of DOWN-SHIFT, the solenoid valve 85 is turned on by the output of the electric control circuit 90 as shown in FIG. 22B, and the oil chamber 816
is exhausted. The spool 812 is the spring 81
1 and the throttle pressure or low modulator pressure in the oil chamber 815, the oil passage 1b communicates with the drain port 814 and is evacuated, and the input pulley 520 moves in the direction of rapid expansion. As a result, the torque ratio T increases. By controlling the ON time of the solenoid valve 85 in this manner, the torque ratio is increased and a downshift is performed.

In this way, the hydraulic servo 530 of the input (drive side) pulley 520 is supplied with the output hydraulic pressure of the reduction ratio control valve 81, and the output (drive side) pulley 560
Line pressure is guided to the hydraulic servo 570 of the input pulley 520, and if the hydraulic pressure of the hydraulic servo 530 of the input pulley 520 is Pi, and the hydraulic pressure of the hydraulic servo 570 of the output pulley 560 is Po, Po/Pi is the second
It has the characteristics as shown in the graph in Figure 3. For example, when the throttle opening Θ = 50% and the torque ratio T = 1.5 (point a in the diagram) is running, the accelerator is loosened and Θ = 30%. When Po/Pi is maintained as it is, the operation state shifts to point b in the figure with torque ratio T = 0.87, and conversely, when the torque ratio T = 1.5 is maintained, reduction ratio control is performed to control the input pulley. The value of Po/Pi is increased by the output of the mechanism 80 and changed to the value at point C in the figure. In this way, by controlling the value of Po/Pi as necessary, it is possible to set an arbitrary torque ratio corresponding to any load condition.

As described above, the method for controlling the reduction ratio of a continuously variable automatic transmission for vehicles according to the present invention is based on the rotation speed difference between the input pulley control target rotation speed and the actual input pulley rotation speed, which is set in advance according to the vehicle running conditions. is greater than the set value, the upshift electromagnetic solenoid means or the downshift electromagnetic solenoid means is operated continuously, and when the rotation speed difference is less than the set value, the upshift electromagnetic solenoid means is activated in accordance with the magnitude of the difference. Since duty control is performed in which the operating time of the solenoid means or downshift electromagnetic solenoid means changes, the reduction ratio changing speed can be adjusted depending on the difference between the actual input pulley rotation speed and the input pulley control target rotation speed. This allows for smooth shift control with excellent responsiveness.

In addition, this speed change control makes it possible to perform minute speed change control, so even if the diameter of the hydraulic oil supply passage to the hydraulic servo of the input and output pulleys is set large, the hydraulic pressure during speed change control will be reduced. Fluctuations can be reduced, and shift shocks can be prevented during minute shift control. On the other hand, by setting the diameter of the hydraulic oil supply passage to be large, the V-belt can be quickly returned to the maximum deceleration state in the event of a sudden stop, thereby preventing a shock when restarting.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a continuously variable automatic transmission for vehicles;
The figure is a circuit diagram of the hydraulic control device, Figure 3 is a graph showing the output oil pressure characteristics of the reduction ratio control valve, Figure 4 is a graph showing the characteristics of the second throttle pressure output by the throttle valve, and Figures 5 and 6 are graphs showing the characteristics of the second throttle pressure output by the throttle valve. Figure 7 is a graph showing the first throttle pressure characteristics output by the throttle valve, Figure 7 is a graph showing the low modulator pressure characteristics output by the low modulator valve, Figure 8 is a graph showing the hydraulic characteristics occurring in oil passage 2, Figure 9 , Figure 10,
Fig. 11 is a graph showing the line pressure characteristics output by the pressure regulating valve, Fig. 12 is a block diagram of the electronic control device,
Fig. 13 is a graph showing the fluid coupling equal fuel consumption curve, Fig. 14 is a graph showing the fluid coupling output equal horsepower curve, Fig. 15 is a graph showing the best fuel consumption fluid coupling output line, and Fig. 16 is a graph showing the fluid coupling output line. A graph showing the combined output performance characteristics of the engine and fluid coupling at each throttle opening, Fig. 17 is a graph showing the best fuel efficiency input pulley rotation speed control line, Figs. 18, 19, and 20 are reduction ratio control A flowchart showing a method of controlling the mechanism; FIG. 21 is a graph showing the relationship between the magnitude of the difference between the input pulley control target rotation speed Nc and the actual input pulley rotation speed and the operation of the electromagnetic solenoid valves 84 and 85; FIG. A, B, and C are diagrams for explaining the operation of the reduction ratio control mechanism, and FIG. 23 is a graph for explaining the operation. In the figure, 20... Oil pump, 30... Pressure regulating valve, 40... Throttle valve, 50... Reduction ratio detection valve, 60... Manual valve, 70... Lock-up control mechanism, 80... Reduction ratio control mechanism, 81...
Reduction ratio control valve, 84... Electromagnetic solenoid valve for upshift, 85... Electromagnetic solenoid valve for downshift, 400... Fluid coupling, 500
... V-belt type continuously variable transmission, 600 ... Planetary gear transmission mechanism, 90 ... Electronic control circuit, 91 ... Shift lever switch, 92 ... Input pulley rotation speed sensor, 94 ... Throttle sensor, 99 ... ...Idling switch.

Claims (1)

[Claims] 1. An input pulley and an output pulley that are provided on the input shaft and output shaft, respectively, and whose effective diameters are increased or decreased by a hydraulic servo, a V-belt that transmits power between the input pulley and the output pulley, and vehicle running conditions. an electronic control circuit comprising a detection means and a logic means for outputting an output according to an input from the detection means; a reduction ratio control means for supplying and discharging hydraulic oil to a hydraulic servo of the input pulley or the output pulley; It consists of an upshift electromagnetic solenoid means and a downshift electromagnetic solenoid means that control the ratio control means, and the input pulley and a hydraulic control circuit including a reduction ratio control mechanism that controls the supply and discharge of hydraulic oil to the hydraulic servo of the output pulley and changes the reduction ratio of the V-belt continuously variable automatic transmission according to the vehicle running conditions; In the control method for a continuously variable automatic transmission for a vehicle, the electronic control circuit determines a rotation speed difference between an input pulley control target rotation speed preset according to vehicle running conditions and an actual input pulley rotation speed to a set value. In this case, the upshift electromagnetic solenoid means or the downshift electromagnetic solenoid means are operated continuously, and when the rotation speed difference is less than the set value, the upshift electromagnetic solenoid means or A reduction ratio control method for a continuously variable automatic transmission for a vehicle, characterized by performing duty control in which the operating time of a downshift electromagnetic solenoid means is varied.