JPS61105352A - Shift controller for stepless transmission - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a speed change control device for a continuously variable transmission.

(B) Prior art As a conventional speed change control device for a continuously variable transmission, for example, Japanese Patent Application Laid-open No. 58-1999. There is one shown in Japanese Patent No. 72758. The speed change control device of this continuously variable transmission prevents a temporary drop in oil pressure in the pulley cylinder chamber during sudden speed changes by providing a flow restriction device that restricts the flow of oil discharged from the pulley cylinder chamber. This prevents the belt from slipping.

(c) Problems to be solved by the invention However, in the conventional speed change control device for a continuously variable transmission as described above, when the flow rate limiting effect of the flow rate limiting device is made very large, the oil pressure in the pulley cylinder chamber temporarily decreases. However, there is a problem that the speed change response becomes poor due to the delay in discharging the hydraulic pressure. Further, if the discharge capacity of the oil pump is small, even if a flow rate restriction device is provided, a temporary drop in oil pressure in the cylinder chamber may occur. In other words, when performing a rapid downshift, for example, the deviation between the target gear ratio and the actual gear ratio increases immediately after the gear shift starts, so the stroke of the gear change control valve increases, sending a large amount of oil into the driven pulley cylinder chamber. becomes possible. However, the discharge flow rate of the oil pump is proportional to the engine rotation speed, and the engine rotation speed is low immediately after the start of a shift, and the discharge flow rate is small.As a result, a lack of oil in the driven pulley cylinder chamber occurs immediately after the start of a shift. , V
Belt slippage occurs. As a result, the durability of the V-belt decreases, and vibrations occur due to intermittent slipping of the V-belt. It is an object of the present invention to provide a shift control device for a continuously variable transmission that prevents this and enables responsive shift.

(d) Means for Solving the Problems The present invention achieves the above object by setting the flow rate characteristics of oil supplied to the pulley cylinder chamber through the speed change control valve in accordance with the discharge flow rate of the oil pump. That is,
In the speed change control device for a continuously variable transmission according to the present invention, the flow rate of oil supplied to the pulley cylinder chamber through the speed change control valve is
Even when the deviation between the target value and the actual value is maximum, it is set so as not to exceed the oil pump discharge flow rate.

(E) Function By having the above configuration, the flow rate supplied to the pulley cylinder chamber is controlled so as not to exceed the oil pump discharge flow rate even during sudden speed changes, and slippage of the V-belt is prevented. . Further, since the gear shift is rapidly performed in response to an increase in the oil pump discharge flow rate, a sufficient shift response speed can be obtained.

(F) Co-educational example; FIG. 2 shows a power transmission mechanism of a continuously variable transmission. A fluid coupling 12, which is a fluid transmission device, is connected to an output shaft 10a of an engine 10. The fluid coupling 12 is equipped with a lock-up mechanism, and can mechanically connect or disconnect the pump impeller 12b on the input side and the turbine runner 12c on the output side by controlling the oil pressure in the lock-up oil chamber 12a. be. The output side of the fluid coupling 12 is the rotating shaft 13
The zero rotation shaft 13 is connected to the forward/reverse switching mechanism 15. The zero/reverse switching mechanism 15 has a planetary gear mechanism 17, a forward clutch 40, and a reverse brake 50. The planetary gear mechanism 17 includes a sun gear 19 and 2
It consists of a pinion carrier 25 having two pinion gears 21 and 23, and an internal gear 27.

The two pinion gears 21 and 23 mesh with each other, the pinion gear 21 meshes with the sun gear 19, and the pinion gear 23 meshes with the internal gear 27. Sun gear 19 is always connected to rotary shaft 13 so as to rotate together with it. The pinion carrier 25 can be connected to the rotating shaft 13 by a forward clutch 40. The internal gear 27 also has a reverse brake 50.
It can be fixed to a stationary part by. The pinion carrier 25 is connected to a drive shaft 14 disposed around the outer periphery of the rotating shaft 13. A drive pulley 16 is provided on the drive shaft 14 . The drive pulley 16 includes a fixed conical plate 18 that rotates together with the drive shaft 14 , and a V-shaped pulley groove formed by opposing the fixed conical plate 18 . The movable conical plate 22 is movable in the axial direction of the movable conical plate 22. The driving pulley cylinder chamber 20 is composed of two chambers 20a and 20b, and has a pressure receiving area twice that of a driven pulley cylinder chamber 32, which will be described later. The driving pulley 16 is coupled to a driven pulley 26 by a V-belt 24 in a transmission manner. The driven pulley 26 is provided on the driven shaft 28. The driven pulley 26 includes a fixed conical plate 30 that rotates together with the driven shaft 28, and a V-shaped pulley groove formed by opposing the fixed conical plate 30.
8, a movable conical plate 34 is movable in the axial direction. By these drive pulley 6, V belt 24 and driven pulley 26, ■belt type continuously variable transmission mechanism 29
is configured. A drive gear 46 is fixed to the driven shaft 28, and this drive gear 46 meshes with a hydraulic gear 48 on the idler shaft 52. A pinion gear 54 provided on the idler shaft 52 is always engaged with the final gear 44. A pair of pinion gears 58 and 60 constituting a differential device 56 are attached to the final gear 44, and a pair of side gears 62 and 64 are engaged with the pinion gears 58 and 60.
and 64 are connected to output shafts 66 and 68, respectively.

The output shaft 10 of the engine 10 is attached to the power transmission mechanism as described above.
The rotational force input from a is transmitted to the fluid coupling 12
and is transmitted to the forward/reverse switching mechanism 15 via the rotating shaft 13, and via the planetary gear mechanism 17, which is in an integrally rotating state when the forward clutch 40 is engaged and the reverse brake 50 is released. The rotational force of the rotating shaft 13 is transmitted to the drive shaft 14 in the same rotational direction, and when the forward clutch 40 is released and the reverse brake 50 is engaged, the rotational force of the rotating shaft 13 is transmitted to the drive shaft 14 in the same rotational direction. The rotational force of the rotary shaft 13 is transmitted to the drive shaft 14 with the rotation direction reversed. The rotational force of the drive shaft 14 is applied to the drive pulley 1
6. The differential device 5 is connected to the V belt 24, the driven pulley 26, the driven shaft 28, the drive gear 46, the idler gear 4, the idler shaft 52, the pinion gear 54, and the final gear 44.
6, and the output shafts 66 and 68 rotate in the forward or reverse direction. Note that when both the forward clutch 40 and the reverse brake 50 are released, the power transmission mechanism is in a neutral state. When transmitting power as described above,
Movable conical plate 22 of drive pulley 16 and driven pulley 26
The V-belt 24 is moved by moving the movable conical plate 34 in the axial direction.
By changing the radius of contact with the drive pulley 16
For example, if the width of the V-shaped pulley groove of the drive pulley 16 is expanded and the width of the V-shaped pulley groove of the driven pulley 26 is reduced, the rotation ratio between the drive pulley 16 and the driven pulley 26 can be changed. The contact radius of the V-belt on the pulley 16 side becomes smaller, and the contact radius of the V-belt on the driven pulley 26 side becomes larger, resulting in a large gear ratio. If the movable conical plates 22 and 34 are moved in the opposite direction, the gear ratio will become smaller, completely opposite to the above.

Next, a hydraulic control device for this continuously variable transmission will be explained. As shown in Fig. 1, the hydraulic control device includes an oil pump 1.
01, line pressure regulating valve 102, manual valve 104, speed change control valve 106, mW pressure switching valve 108, speed change motor 110
．． Speed change operation mechanism 112, throttle valve 114, constant pressure regulating valve 116, solenoid valve 118, coupling pressure regulating valve 12
0, a lock-up control valve 122, etc.

Oil pump 101 sucks oil in tank 130 through strainer 131 and discharges it into oil path 132 . The oil discharged from the oil passage 132 is supplied to the boat 14 of the line pressure regulating valve 102.
6b, 146d, and 146e, and the pressure is regulated to a predetermined line pressure as described later. The oil passage 132 is
Boat 192C of throttle valve 114 and speed change control valve 1
It also communicates with boat 172c of No. 06. Also, oil path 1
32 also communicates with the boat 204b of the constant pressure regulating valve 116. Note that a line pressure relief valve 13 is installed in the oil passage 132.
3 is provided to prevent the line pressure from becoming abnormally high.

The manual valve 104 has five boats 134a and 134b.
, 134C, 1134d and 134e.
and a spool 136 having two lands 136a and 136b corresponding to the valve hole 134.

The spool 136, which is operated by a select lever (not shown) on the driver's seat, has five stop positions: P, R, N, D, and L ranges. Bo) 134a and 13
4e is a drain boat, and boat 134b is oil channel 1.
42 communicates with the forward clutch 40. Note that the oil passage 142 is provided with a one-way orifice 143 that has a throttling effect only when supplying hydraulic pressure to the forward clutch 40. In addition, the ports 192b and 192d of the throttle valve 114 are connected to the ports 192b and 192d by the oil passage 140.
The boat 134d communicates with the reverse brake 50 through an oil passage 138. Note that the oil passage 138 is provided with a one-way orifice 139 that has a throttling effect only when supplying hydraulic pressure to the reverse brake 50. When the spool 136 is in the P position, the throttle valve 114 (described later)
The boat 134c, in which the throttle pressure of the oil passage 140 regulated by the throttle pressure is increased, is closed by the land 136a.
The reverse brake 50 is drained from the drain boat 134e via the oil passage 138. When the spool 136 is in the R position, the boats 134C and 134d communicate between the lands 136a and 136b, and the throttle pressure of the oil passage 140 is supplied to the reverse brake 50, while the forward clutch 40 is It is drained via 134a. When the spool 136 comes to the N position, the boat 13
4C is sandwiched between lands 136a and 136b and cannot communicate with other boats, while boat 13
Since both 4b and 134d are drained, the reverse brake 50 and the forward clutch 4 are
0 are drained together. When the spool 136 is in the D or L position, the boat 134b and the boat 134C communicate between the lands 136a and 136b, and throttle pressure is supplied to the forward clutch 40, while the reverse brake 50 is connected to the port 134e. It is drained after. As a result, when the spool 136 is in the P or N position, both the forward clutch 40 and the reverse brake 50 are released and power transmission is entrusted, and the rotational force of the rotating shaft 13 is transmitted to the drive shaft 14. Spool 1
When the spool 136 is in the R position, the reverse brake 50 is engaged and the output shafts 66 and 68 are driven in the reverse direction as described above, and when the spool 136 is in the D or L position, the forward clutch 40 is engaged and the output shaft 66 and 68 will be driven in the forward direction.

Although there is no difference between the D position and the L position in terms of the hydraulic circuit as described above, the shift motor 110 (described later) is used to electrically detect the 1st position and change gears according to different shift patterns. operation is controlled.

The line pressure regulating valve 102 has seven boats 146a, 14
6b, 146c, 146d, 146e, 146f and 1
A valve hole 146 having a diameter of 46g and five lands 148a, 148b, 148c, 148 corresponding to this valve hole 146.
d and 148e, an axially movable sleeve 150, and two springs 15 provided concentrically between the spool 148 and the sleeve 150.
2 and 154. The sleeve 150 is
It is designed to receive a pressing force in the left direction in FIG. 1 from the pressing member 158. The pressing member 158 is supported so as to be movable in the axial direction with respect to the valve body, and the other end thereof is connected to a groove 2 provided on the outer periphery of the movable conical plate 22 of the drive pulley 16.
It meshes with 2a. Therefore, when the gear ratio increases, the sleeve 150 moves to the left in the figure, and when the gear ratio decreases, the sleeve 150 moves to the right in the figure. Outer spring 1 of the two springs 152 and 154
52 is always in a compressed state with both ends in contact with the sleeve 150 and spool 148, respectively, but the spring 154 on the inner circumferential side is designed to be compressed only after the sleeve 150 moves leftward in the figure by a predetermined amount or more. Port 146a of the line pressure regulating valve 102 is a drain boat.

The boat 146g has an oil line 140 which is a throttle pressure circuit.
Throttle pressure is supplied from The boat 146C communicates with an oil passage 164 which is a drain circuit. Boats 146b, 146d, and 146e communicate with oil passage 132, which is a line pressure circuit. Boat 146f is oil channel 16
5 to the boat 230b of the coupling pressure regulating valve 120
It communicates with Note that the oil passage 165 is an orifice 199.
It communicates with the line pressure oil passage 132 via. Note that orifices 166 and 170 are provided at the inlets of ports 146b and 146g, respectively. As a result, the spool 148 of this line pressure regulating valve 102 has a spring 152.
force (or force due to springs 152 and 154)
and port 146g oil pressure (throttle pressure) is land 1
Two leftward forces act on the area difference between lands 148d and 148c, and a rightward force acts on the area difference between lands 148a and 148b due to the hydraulic pressure (line pressure) of port 146b. However, the spool 148 adjusts the amount of oil leaking from port 146d to port 146C and the amount of oil leaking from port 146e to port 146f so that the horizontal forces are always balanced.
Control the line pressure of b. Therefore, the line pressure increases as the gear ratio increases, and the line pressure increases as the throttle pressure acting on the port 146g increases. Adjusting the line pressure in this way requires increasing the V-belt pressing force of the pulley as the gear ratio increases, and the higher the throttle pressure (i.e., the lower the negative pressure in the engine intake pipe), the lower the engine output torque. Since this is large, the hydraulic pressure is increased to increase the V-belt pressing force of the pulley and to increase the power transmission torque due to friction.

The speed change control valve 106 to which the present invention is applied has five ports 172a, 172b, 172C1172d, and 172C.
2e, and a spool 174 having three lands 174a, 174b, and 174c corresponding to the valve hole 172.

It consists of a spring 175 that pushes the spool 174 to the left in the figure. The bow) 172b communicates with the drive pulley cylinder chamber 20 via an oil passage 176, and the bow h
172a and port 172e are drain ports.

Note that an orifice 177 is provided at the outlet of the port 172a. The port 172d communicates with the driven pulley cylinder chamber 32 via an oil passage 179. The bow h172c communicates with the oil passage 132, which is a line pressure circuit, and is supplied with line pressure. The left end of the spool 174 is rotatably connected to a substantially central portion of a lever 178 of a shift operation mechanism 112, which will be described later, by a pin 181. Since the axial cross section of the end of the land 174b is provided with a curved tapered part, the line pressure supplied to the port 172C is
2b, but some of it is discharged to port 172a, so that the pressure at port 172b is determined by the ratio of inflow oil to discharge oil.

Therefore, as the spool 174 moves to the left, the line pressure side clearance of the bow 172b increases and the discharge side clearance decreases, so the pressure at the port 172b gradually increases.On the other hand, the port 172cl normally has a bow ) 172c line pressure is supplied. port 1
The hydraulic pressure at port 72b is supplied to the driving pulley cylinder chamber 20 via an oil passage 176, and the hydraulic pressure at port 172d is supplied to the driven pulley cylinder chamber 32 via an oil passage 179. Therefore, when the spool 174 moves to the left, the pressure in the drive pulley cylinder chamber 20 increases and the drive pulley 1
The width of the V-shaped pulley groove of the driven pulley 26 becomes smaller, while the width of the V-shaped pulley groove of the driven pulley 26 becomes larger. That is, the V-belt contact radius of the driving pulley 16 becomes larger and the V-belt contact radius of the driven pulley 26 becomes smaller, so that the gear ratio becomes smaller. Conversely, when the spool 174 is moved to the right, the gear ratio increases due to the exact opposite effect to the above. Note that the land 174C is also provided with a tapered portion so that the flow rate changes depending on the stroke.
As a result, the flow rate supplied to the driving pulley cylinder chamber 20 and the driven pulley cylinder chamber 32 has the characteristics shown in FIG. 3, and a temporary flow shortage in the driving pulley cylinder chamber 20 and the driven pulley cylinder chamber 32 is prevented. , which will be discussed later.

As described above, the lever 178 of the speed change operation mechanism 112 is connected to the spool 174 of the speed change control valve 106 at approximately the center thereof.
is connected to the lever 178 by a pin 181.
One end is connected to the aforementioned pressing member 158 by a pin 183, and the other end is connected to a rod 182 by a pin 185. Rod 182 is rack 182C
This rack 182C has a variable speed motor 110.
The pinion gear 110a is engaged with the pinion gear 110a. In such a shift operation mechanism 112, the I
By rotating the pinion gear 110a of the variable speed motor 110 controlled by I, e7. When the door 182 is moved, for example, to the right in the drawing, the lever 178 rotates clockwise about the pin 183, and moves the spool 174 of the speed change control valve 106 connected to the lever 178 to the right. As shown in FIG. 1, the movable conical plate 22 of the drive pulley 16 moves to the left in FIG.
The interval between the V-shaped pulley grooves of the driven pulley 26 becomes larger, and at the same time, the interval between the V-shaped pulley grooves of the driven pulley 26 becomes smaller, and the gear ratio becomes larger. Since one end of the lever 178 is connected to the pressing member 158 by the pin 183, when the pressing member 158 moves to the left in FIG. 1 as the movable conical plate 22 moves, the lever 178 The lever 178 rotates clockwise about the pin 185 on the other end side as a fulcrum. For this reason, the spool 174 is pulled back to the left, attempting to bring the drive pulley 16 and the driven pulley 26 into a state where the gear ratio is small. This operation causes the spool 174, drive pulley 16, and driven pulley 26 to
is stabilized at a predetermined speed ratio in accordance with the rotational position of the speed change motor 110. The same is true when the speed change motor 11O is rotated in the opposite direction. When moving to the stroke region, the changeover detection switch 298 is activated, and this signal is input to the speed change Mm device).Therefore, when the speed change motor 110 is operated according to a predetermined speed change pattern, the speed change ratio changes in accordance with this. Therefore, by controlling the speed change motor 110, the speed change of the continuously variable transmission mechanism can be controlled.

Variable speed motor (in the following explanation, "step motor")
110, the rotational position of which is determined in accordance with the pulse number signal sent from the speed change control device. The pulse number signal from the speed change control device is given according to a predetermined speed change pattern.

The regulating pressure switching valve 108 has its valve body connected to the speed change operation mechanism 112.
It is formed integrally with the rod 182 of.

That is, the regulating pressure switching valve 10g has ports 186a and 18
It consists of a valve hole 186 having holes 6b, 186C and 186d, and lands 182a and 182b formed on the rod 182. Port 186a communicates with oil passage 188. The port 186b is connected to the solenoid valve 1 via the oil passage 190.
It communicates with 18. 188c communicates with the oil passage 189. Port 186cl is a drain port.

(usually bow) 186a and port 186b are land 18
2a and 182b, but the rod 1
Port 186a is closed and ports 186b and 186c are brought into communication only when gear ratio 82 moves beyond the position corresponding to the maximum speed ratio value to an overstroke region.

The throttle valve 114 has ports L92a, 192b, 1
A valve hole 192 having 92c, 192d, 192e, 192f and 192g and five lands 194a, 194b, 194c, 194d and 194 corresponding to the valve hole 192.
It is made up of a spool 194 having a diameter of 1.e, and a negative pressure diaphragm 198 that applies a pushing force to the spool 194. When the negative pressure in the engine intake pipe is lower than a predetermined value (for example, 300 mmHg) (close to atmospheric pressure), the negative pressure guyafram 198 applies a force inversely proportional to the negative pressure to the spool 194, and the negative pressure in the engine intake pipe is lowered. If the value is higher than a predetermined value, no force is applied at all. The port 192a is a drain boat, the ports 192b and 192d are in communication with an oil passage 140 which is a throttle pressure circuit, the port 192c is in communication with an oil passage 132 which is a line pressure circuit, and the ports 192e and 192f are in communication with an oil passage 132 which is a line pressure circuit. The drain port (also known as bow) 192g communicates with the oil passage 189 described above. Orifices 202 and 203 are provided at the inlets of port 192b and port 192g, respectively. The hydraulic pressure of port 192g is connected to land 19 in spool 194.
4d and the land 194e and the force due to the negative pressure diaphragm 198, and the force acting on the area difference between the lands 194a and 194b due to the hydraulic pressure of 192b. However, the throttle valve 114 uses the line pressure of the port 192c as a pressure source and uses the port 192e as a discharge port to perform a well-known pressure regulating action so that the forces in both directions are balanced. The force due to the hydraulic pressure of the port 192g and the negative pressure diaphragm 19
Throttle pressure corresponding to the force caused by 8 is generated. The throttle pressure obtained in this manner is regulated in accordance with the engine intake pipe negative pressure, and therefore corresponds to the engine output torque. That is, if the engine output torque is large, the throttle pressure also becomes a correspondingly high oil pressure. Note that the throttle pressure is also adjusted by the oil pressure (adjustment pressure) of the port 192g as described later.

The constant pressure regulating valve 116 has ports 204a, 204b, 2
a valve hole 204 having 04c, 204d and 204e;
A spool 206 having lands 206a and 206b, and a spring 208 that pushes the spool 206 to the left in the figure.
It consists of.

Ports 204a and 204C communicate with oil passage 209. Port 204b communicates with oil passage 132, which is a line pressure circuit. Ports 204d and 204e are drain ports. Orifice 2 is located at the entrance of port 204a.
16 is the provision. The constant pressure regulating valve 116 has a function of regulating a constant hydraulic pressure corresponding to the force of the spring 208 by a well-known pressure regulating function, and supplying this to the oil passage 209. Note that the oil passage 209 and the aforementioned oil passages 188 and 189 are connected via choke-type throttle valves 250 and 252, respectively. In addition, a filter 2 is provided in the oil passage 209.
11 are provided.

The solenoid valve 118 has a solenoid 224 that can adjust the amount of oil discharged from the oil passage 190 to the port 222 by a plunger 224a biased in the closing direction by a spring 225.
It is made up of.

The duty ratio of the solenoid 224 is controlled by the speed change control device, and the oil in the oil passage 190 is discharged in proportion to the amount of energization, so the oil pressure (adjusted pressure) of the oil passage 190 is controlled in inverse proportion to the amount of energization. In an idling state where the vehicle is stopped, the rod 182 moves to the overstroke region, the regulating pressure switching valve 108 is in the state shown in the lower half of FIG. 1, and the oil passage 190 communicates with the oil passage 189. Solenoid valve 11
8 acts on port 192g of throttle valve 114. As a result, the throttle pressure is controlled so that the forward clutch 16 or the reverse clutch 26 is slightly engaged. 0 This throttle pressure is always supplied to the forward clutch 16 or the reverse clutch 26 before starting. As a result, a predetermined creep torque can be obtained, and the system torque is also reduced when selecting N-D or N4R.As soon as zero start is started, the throttle pressure increases and the forward clutch 16 or reverse clutch 26 is fully tightened. On the other hand, during normal driving, the regulating pressure switching valve 108 is in the state shown in the upper half, and the oil passage 190 and the oil passage 188 are in communication, so that the switching of the lock-up control valve 122 can be controlled by the regulating pressure as described later. becomes.

The coupling pressure regulating valve 120 has ports 230a, 23
It consists of a valve hole 230 having holes 0b, 230c, 230d, and 230e, a spool 232 having lands 232a and 232b, and a spring 234 that pushes the spool 232 to the left in the figure. Ports 230a and 23
0c communicates with an oil passage 235, and drain oil from the line pressure regulating valve 102 is supplied from the oil passage 165 to the bow 230b, and ports 230d and 230e are drain boats. An orifice 236 is provided at the entrance of the bow) 230a. The coupling pressure regulating valve 120 uses the hydraulic pressure supplied from the oil passage 165 to the port 230b as a hydraulic pressure source to regulate a constant oil pressure (coupling pressure) corresponding to the force of the spring 234, and supplies this to the oil passage 235. It has the function of This coupling pressure is used as the operating pressure of the fluid coupling 12 and is also used to control the operation of the lock-up mechanism.

The lock-up control valve 122 is connected to the boats 240a, 240
b, 240C1240d, 240e, 240f, 240
a valve hole 240 having g and 240h, and a land 242a
, 242b, 242C, 1242d and 242e. Boat) 240a and Boat 240g are drain boats, and Boat 240a and Boat 240g are drain boats.
0b communicates with the oil passage 209, and 240c and 240f communicate with the lock-up oil chamber 12a via the oil passage 243.
The bow h240d is connected to an oil passage 245 that communicates with the fluid coupling 12. A constant coupling pressure is supplied to the boat 240e from the oil passage 235. The bow 1240h is connected to the oil passage 188 described above. The inlets of boats 240b, 240C 1240g and 240h each have orifices 246.24
7.248 and 249 are provided. This lock-up control valve 122 has a function of controlling the supply of hydraulic pressure to the fluid coupling 12 and the lock-up oil chamber 12a. The spool 242 has a ball 1-24 which acts on the area difference between the lands 242a and 242b.
0b (this oil pressure is a constant pressure regulated by the constant pressure regulating valve 116) and the boat 240 acting on the area difference between the land 242b and the land 242C.
The switching is performed depending on the balance between the hydraulic pressure of c and the hydraulic pressure (adjustment pressure) of the boat 240h acting on the end of the land 242e. When the spool 242 is in the position shown in the upper half of FIG. 235
coupling pressure is supplied to the fluid coupling 12. Note that the fluid coupling 12 is connected to the oil passage 245.
Relief valve 2 to prevent abnormally high oil pressure from acting on the
Also, when the spool 242 is in the upper half position, the boat 240f and the boat 240g communicate between the lands 242d and 242e, and the oil pressure in the lock-up oil chamber 12a is drained from the boat 240g. Therefore, the lock-up mechanism is engaged and enters the lock-up state. Conversely, when the spool 242 is in the position shown in the lower half of FIG. The coupling pressure of the oil passage 235 is supplied to the lock-up oil chamber 12a through the oil passage 243.
40d is closed by land 242C and land 242d. Therefore, the lock-up mechanism is in a released state, and the fluid coupling 12 has a lock-up oil chamber 1.
The operating pressure is supplied from the 2a side. The oil pressure of the fluid coupling 12 is maintained at a constant pressure by a pressure holding valve 252 provided in the oil passage 245. The oil discharged through the pressure holding valve 252 passes through the oil passage 254 to the cooler 256.
where it is cooled and used for lubrication. Note that the oil passage 254 is provided with a cooler pressure retention valve 258, and the oil discharged from the cooler pressure retention valve 258 is transferred to the oil passage 1.
64 and is returned to the suction port of the oil pump 101.

The oil passage 254 is led to a moving part between the pressing member 158 and the valve body, and is designed to lubricate this.

In addition, the oil passage 254 is connected to the oil passage 254 via an orifice fixture 259.
35, so that the minimum required amount of oil is always supplied.

Next, the flow characteristics of the speed change control valve 106, which is the gist of the present invention, will be further explained. Land 174c of spool 174
has a shape in which the outer diameter gradually changes in the axial direction. In a steady state, oil flows into the boat 172d from the boat 172c side where line pressure is applied through the gap between the land 174c and the valve hole 172, and this oil flows through the oil passage 179 to the driven pulley cylinder chamber 32. is supplied to. In the case of a downshift, the step motor 110 rotates clockwise in FIG. 1 at a constant speed by a predetermined portion depending on the deviation between the target speed ratio and the actual speed ratio.

The rotation of the step motor 110 is transmitted to the spool 174 via the speed change operation mechanism 112, and the spool 174 is connected to the first
Move to the right in the diagram. At the initial stage when the spool 174 starts moving to the right, the land 174c and the valve hole 1
The T clearance on the line pressure action side between 72 and 72 is relatively small.
However, since the outer diameter of the run f'174c changes in the axial direction, the above-mentioned clearance gradually increases as the spool 174 moves. That is, during a downshift, hydraulic pressure is first supplied to the driven pulley cylinder chamber 32 with the flow rate restricted through a relatively small gap, and as the gear ratio increases and the engine rotation speed increases as the gear shift progresses, this Along with this, the discharge flow rate of the oil pump 101 also increases, but at the time the oil pump discharge flow rate increases, the gap between the land 174c and the valve hole 172 is enlarged. Therefore, oil is rapidly supplied to the driven pulley cylinder chamber 32, and the speed change progresses rapidly. The characteristics of the target speed ratio, actual speed ratio, stroke of the speed change control valve, flow rate supplied through the speed change control valve, and output shaft torque with respect to changes in time during the speed change are shown in FIG. 3. As can be seen from FIG. 3, the flow rate supplied to the driven pulley cylinder chamber 32 through the gap in the speed change control valve 106 is set so as not to exceed the oil pump discharge flow rate. Therefore, the oil pressure in the driven pulley cylinder chamber 32 will not temporarily drop due to insufficient supply of oil, and belt slippage will not occur.Moreover, after the oil pump discharge flow rate increases, the speed can be changed. Since this is done rapidly, a sufficient speed change response speed is ensured. That is, the speed change is determined by the moving speed of the movable conical plate 34 of the driven pulley 26, that is, the amount of oil supplied to the driven pulley cylinder chamber 32, and a large amount of oil is supplied while the discharge flow rate of the oil pump 101 is small. Even if the speed change control valve 106 is operated as shown in FIG. The above shifting speeds are almost the same. As mentioned above, (1) belt slipping does not occur; (2) vibrations due to intermittent belt slipping also do not occur; therefore, (1) belt durability is improved. In addition, the land 174 of the spool 174
C is not limited to a curved tapered part.

As long as the above-mentioned characteristics are satisfied, a straight taper or a two-stage taper with different angles may be used.Also, as is clear from the above explanation, the land 1 that acts during upshifting may be used.
74b is also provided with a tapered portion, but during upshifting, the speed is changed so that the discharge flow rate of the oil pump 101 is reduced, so the tapered portion of the land 174b is similar to the land 174c.
It is preferable to set the flow rate to increase more gradually with respect to the stroke of the spool 174 than the tapered portion.

(G) As described in detail, according to the present invention, the flow rate characteristics of oil supplied to the pulley cylinder chamber through the speed change control valve that moves according to the deviation between the target value and the actual value are adjusted according to the deviation between the target value and the actual value. Even when the oil pressure is at its maximum, it is set so that it does not exceed the oil pump discharge flow rate, which changes depending on the engine speed, so the oil pressure in the pulley cylinder chamber will not drop temporarily even during sudden gear changes. ■It is possible to prevent the occurrence of belt slippage, vibration, etc.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a hydraulic circuit of a continuously variable transmission having a speed change control device according to the present invention, FIG. 2 is a diagram showing a power transmission mechanism of the continuously variable transmission, and FIG. FIG. 3 is a diagram showing flow characteristics and the like. 16... Drive pulley, 20... Drive pulley cylinder chamber, 26... Driven pulley, 32... Drive pulley cylinder chamber, 106... Speed change control valve, 172... Valve hole,
174...Spool, 174a-174c...Land. Patent applicant Nissan Motor Co., Ltd. agent Patent attorney Toshiyuki Miyauchi “Figure 3

Claims (1)

[Scope of Claims] 1. A speed change control device for a continuously variable transmission having a driving pulley and a driven pulley whose groove distances are variable depending on the hydraulic pressure acting on the pulley cylinder chamber, which controls the deviation between the target value and the actual value. In a speed change control device that controls the distribution of hydraulic pressure to both pulley cylinder chambers by a speed change control valve that moves according to A speed change control device for a continuously variable transmission, characterized in that the flow rate is set so that the flow rate does not exceed an oil pump discharge flow rate even when the flow rate is at a maximum. 2. The flow rate of oil through the speed change control valve is set by the clearance between the valve hole and the outer circumference of the land of the spool whose outer diameter changes in the axial direction. Shift control device for continuously variable transmission.