JP2848178B2 - Control device for belt type continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a belt-type continuously variable transmission.

[0002]

2. Description of the Related Art A belt-type continuously variable transmission is a transmission that uses a belt and a pulley to continuously change the gear ratio. As shown in FIG. (Not shown), a primary pulley (input shaft) 1, a secondary pulley (output shaft) 2 connected to a front axle, and a primary pulley 1 and a secondary pulley 2. A belt 3 and a hydraulic control device 4 for controlling the groove widths Wp and Ws of the primary pulley 1 and the secondary pulley 2 are provided.

[0003] Primary pulley 1, secondary pulley 2
Is provided with shafts 1a and 2a having a predetermined inclined surface, movable sheaves 1b and 2b, and a primary cylinder 1c and a secondary cylinder 2c provided on the back of the movable sheaves 1b and 2b, respectively. , Which can be slid on the shafts 1a and 2a by the ball spline, and the primary hydraulic pressure P supplied from the hydraulic control device 4.
p, groove width Wp, Ws of pulley by secondary hydraulic pressure Ps
Is made variable. The hydraulic control device 4 is provided with an electronic control device (not shown).
Signals such as an engine speed and a vehicle speed are input, and the hydraulic pressure supplied from the hydraulic pump 5 is controlled based on these signals to control the groove width W of the primary pulley 1 and the secondary pulley 2.
Control p and Ws.

That is, in the low state, as shown in FIG. 2, the groove width Wp of the primary pulley 1 is wide, the groove width Ws of the secondary pulley 2 is narrow, and the speed ratio is increased. Conversely, in the overdrive state, as shown in FIG. 3, the groove width Wp of the primary pulley 1 is narrow, the groove width Ws of the secondary pulley 2 is wide, and the gear ratio is small. The hydraulic device 4
As shown in FIG. 4, the speed ratio control valve 6, the speed limit valve 7,
It is composed of a solenoid valve 8, a manual valve 9, and the like. The solenoid valve 8 is a normally closed type valve, and the duty of the solenoid valve 8 is controlled by the electronic control unit according to the operating state of the vehicle such as the accelerator opening, the engine speed, and the vehicle speed. The solenoid valve 8 is supplied with a predetermined solenoid supply pressure Pv to a port 8a and outputs a control oil pressure (hereinafter simply referred to as “control pressure”) Pva (≦ Pv) according to the duty ratio from the port 8b to control the gear ratio. It supplies to the valve 6 and the shift limiting valve 7. The duty ratio of the solenoid valve 8 is large when the speed ratio is on the low speed side, becomes small when the speed ratio is on the high speed side, and the control pressure Pva
Becomes lower as the speed shifts from the lower gear to the higher gear.

[0005] The high-pressure hydraulic pressure discharged from the hydraulic pump 5 is regulated to a predetermined line pressure PL by a regulator valve (not shown) and supplied to the secondary cylinder 2c to narrow the groove width Ws of the secondary pulley 2. Acts to be. When the control pressure Pva of the solenoid valve 8 is high, the control pressure Pva supplied to the port 6c of the speed ratio control valve 6 pushes the spool 6p leftward in the drawing against the spring pressure of the spring 6s, and the port 6a Is shut off from the port 6b and communicated with the port 6x to gradually discharge the oil in the primary cylinder 1c from the discharge port 6x.
As a result, the groove width Wp of the primary pulley 1 as shown in FIG.
Is maximum, the groove width Ws of the secondary pulley 2 is minimum,
The gear ratio becomes the lower gear.

When the control pressure Pva of the solenoid valve 8 decreases, the spring 6s pushes the spool 6p rightward in the drawing, whereby the ports 6a and 6b are gradually communicated, and the line pressure PL is reduced to the primary cylinder 1c. Supplied to The primary cylinder 1c is the secondary cylinder 2
c, the pressure receiving area is larger than that of the secondary cylinder 2c (FIG. 1).
, The groove width Wp of the primary pulley 1 gradually decreases, and accordingly, the groove width Ws of the secondary pulley 2 increases, and the speed ratio gradually changes to the high speed side.

When the control pressure Pva of the solenoid valve 8 further decreases, the spring 6s pushes the spool 6p further rightward in the drawing, and the ports 6a and 6b are completely connected. As a result, as shown in FIG. 3, the groove width Wp of the primary pulley 1 becomes the minimum, the groove width Ws of the secondary pulley 2 becomes the maximum, and the speed ratio becomes an overdrive state. The solenoid valve 8 controls a part of the control pressure Pva to
To the spool 7 against the spring force of the spring 7s.
By pushing p to the left in the figure, the ports 7a and 7b are shut off, and the oil passage connecting the ports 9b and 9c of the manual valve 9 and the port 6d of the speed ratio control valve 6 is shut off. When the solenoid valve 8 fails for some reason and the control pressure Pva becomes lower than a predetermined pressure, the spool 7p of the shift limiting valve 7 is pushed rightward by the spring 7s as shown in the figure, and the ports 7a and 7b communicate with each other. The ports 9b and 9c of the maneuver valve 9 communicate with the port 6d of the speed ratio control valve 6 via the one-way valves 13 and 14. At this time, the speed ratio control valve 6 is switched to the high speed stage (overdrive state) by the spool 6p being pushed rightward in the drawing to communicate the port 6a with the port 6b.

The clutch supply pressure Pc for driving the forward clutch 11 or the reverse brake 12 only when the shift position of the manifold valve 9 is at L (low speed range) or R (reverse), for example, as shown in FIG. When in the L position, the clutch supply pressure Pc passes through the one-way valve 13 and the ports 7a and 7b of the speed change limiting valve 7,
The spool 6p is supplied to the spring 6
Pushed to the left against s, the gear is switched to the lower gear (low state). Therefore, if the control valve Pva falls below the predetermined pressure due to the malfunction of the solenoid valve 8 while the vehicle is traveling in the normal D range, the transmission will shift to the high gear immediately after the malfunction, so that There is no danger of excessive rotation of the engine due to a downshift. In addition, by changing the shift position of the maneuver valve 9 as needed, the vehicle can run on the low speed side, and sufficient uphill performance can be obtained.

[0009]

However, in the above configuration, there is no regulation of the line pressure PL at the time of failure of the electronic control unit. When traveling, an excessive load is applied to the belt 3 and the durability of the belt is impaired. On the other hand, when the line pressure PL is set uniformly low, the belt is not driven when the input torque is large during traveling on the low speed side. Not only is it not possible to obtain sufficient uphill performance due to slipping, but also there is a problem that the durability of the belt is impaired.

The present invention has been made in view of the above points, and when an abnormality occurs in an electronic control unit for controlling a transmission, the line pressure is adjusted to an appropriate oil pressure according to the shift speed, and a sufficient uphill is achieved. An object of the present invention is to provide a control device for a belt-type continuously variable transmission that ensures performance and improves durability of a belt.

[0011]

According to the present invention, a belt is wound between a primary pulley and a secondary pulley provided on an input shaft and an output shaft. The hydraulic pressure of each of the pulleys of the belt-type continuously variable transmission that changes the groove width by relatively changing the groove width is controlled, and when the supplied control oil pressure is high, the transmission is shifted to the low speed side, and when the supplied control oil pressure is low, the transmission is shifted to the high speed side. A gear ratio control valve for shifting gears, a regulator valve for setting a line pressure to be supplied to the transmission, and a manual valve interposed between the gear ratio control valve and the regulator valve, and open when the supplied control oil pressure is low. When the manual valve is in a specific position, a predetermined hydraulic pressure is applied from the manual valve to the transmission ratio control valve and the regulator valve. And the speed ratio control valve is shifted to a lower speed side to regulate the regulator valve to a high line pressure. When the control hydraulic pressure is high, the speed limit valve is closed, and the speed ratio control valve and the speed change The control valve is configured to include a first control valve that supplies a control oil pressure according to an operation state of the vehicle to the restriction valve, and a second control valve that supplies a control oil pressure according to the operation state of the vehicle to the regulator valve. Things.

[0012]

The first control valve closes the shift limiting valve and shuts off the manual valve, the speed ratio control valve, and the regulator valve when normal. Thereby, the speed ratio control valve controls the speed ratio by the control oil pressure by the first control valve. When the control oil pressure of the first control valve becomes low due to an abnormality of the first control valve or an abnormality of the electronic control device or the like, the shift limiting valve opens, and the manual valve is at a specific position, that is, the L position or the R position. At this time, a predetermined hydraulic pressure is supplied from the manual valve to the gear ratio control valve and the regulator valve. The gear ratio control valve shifts the transmission to a lower gear when the predetermined oil pressure is supplied. As a result, startability and climbability are ensured. The regulator valve increases the line pressure when the predetermined hydraulic pressure is supplied. This prevents the belt from slipping even when the input torque on the low speed side is large.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the accompanying drawings. The same members as those in FIG. 4 are denoted by the same reference numerals. In FIG. 5, the regulator valve 15 has spools 15p and 15p '. The spool 15p' is formed integrally with a land 15m having the same diameter as the spool 15p and a land 15n having a slightly larger diameter than the land 15m. The land 15m is a spring seat. A spring 15sa is provided between one end of the spool 15p and the spring seat 15g,
Springs 15sb are respectively contracted between the other end of the spool 15p and the land 15m of the spool 15p '. The gear ratio control valve 16 is a regulator valve 1
5, the spool 16p 'has a land 16m and a land 16n having the same diameter as the spool 16p, and the spool 16p' has a land 16m.
Are spring seats. A spring 16sa is provided between one end of the spool 16p and the end face of the housing, and the other end of the spool 16p and a land 16m of the spool 16p 'are provided.
The springs 16sb are respectively contracted between them.

The port 15b of the regulator valve 15
Is connected to the discharge port of the hydraulic pump 5 and to the port 16b of the transmission ratio control valve 16, and the port 15xp is connected to the port 15c on the suction port side of the hydraulic pump 5.
Is connected to port 17b of solenoid valve 17 by port 1
5d is connected to the port 7a of the shift limiting valve 7. The port 16a of the transmission ratio control valve 16 is connected to the primary cylinder 1c, the port 16b is connected to the secondary cylinder 2c, the port 16c is connected to the port 8b of the solenoid valve 8, and the port 16d is connected to the port 7a of the shift limiting valve 7. Have been.

A port 9b of the maneuver valve 9 is connected to a port 7b of the shift limiting valve 7 through a one-way valve 13, and a port 9c is connected to a reverse brake 12 and shift-limited through a one-way valve 14. Port 7 of valve 7
b. The ports 9d and 9e are connected to the forward clutch 11. The one-way valves 13, 14
The connection is made so as to allow the flow of the oil only from the ports 9b and 9c of the manual valve 9 in the direction of the port 7b of the shift limiting valve 7. The port 7c of the shift limiting valve 7
It is connected to the port 8b of the solenoid valve 8.

The solenoid supply pressure Pv is supplied to each of the input ports 8a and 17a of the solenoid valves 8 and 17. These solenoid valves 8, 17 are driven by the electronic control unit. The solenoid valve 17 is a normally closed type valve, like the solenoid valve 8, is duty-controlled, outputs a control pressure Pvb (≦ Pv) corresponding to the duty ratio from a port 17a, and supplies it to a port 15c of the regulator valve 15. .

The regulator valve 15 is connected to the hydraulic pump 5
Of the secondary cylinder 2c and the gear ratio control valve 16
To the port 16b. Also, this line pressure PL
Is also supplied to the port 15a of the regulator valve 15. In the manual valve 9, the ports 9 a and 9 d and 9 e are connected to each other at the L position and the 2 position shown in the drawing, and the ports 9 a and 9 d are connected to each other at the D position to supply the clutch supply pressure Pc to the forward clutch 11. When in the N position, the port 9a is cut off from the other ports 9b to 9e,
When in the position, the ports 9a and 9c communicate with each other to supply the clutch supply pressure Pc to the reverse brake 12, and when in the P position, the port 9a is closed.

When the manual valve 9 is in the L position, the ports 9a and 9b are in communication with each other, and the clutch supply pressure Pc is supplied to the port 7b of the shift limiting valve 7 through the one-way valve 13; , The clutch supply pressure Pc is supplied to the port 7b of the shift limiting valve 7 through the one-way valve 14. That is, when the manual valve 9 is at the L position or the R position, the shift limiting valve 7
The clutch supply pressure Pc is supplied to the port 7b.

The operation will be described below. The duty of the solenoid valves 8 and 17 is controlled by the electronic control unit, and the control valves Pva and Pvb are output. Since the speed ratio control valve 16 does not operate unless the control pressure Pva is equal to or higher than the minimum pressure Po, the normal control pressure Pva is equal to or higher than Po (Pva ≧
Du) is controlled so as to be Po). on the other hand,
The shift limiting valve 7 is provided with a control pressure Pv of the solenoid valve 8.
When a is greater than Po, the spool 7p
s, the port 7a and 7b are closed.

Therefore, when the solenoid valve 8 is normal, the shift limiting valve 7 is closed and the regulator valve 1 is closed.
5. The gear ratio control valve 16 is not shut off from the manual valve 9 and the clutch pressure Pc is not supplied. Therefore, even if the manual valve 9 is operated, the regulator valve 15 and the speed ratio control valve 16 are not affected at all.

The regulator valve 15 has a port 15a.
The pressure is adjusted to a predetermined line pressure PL according to the pressure difference between the line pressure PL and the spring pressure of the spring 15sa and the control pressure Pvb and the spring pressure of the spring 15sb. This line pressure PL is supplied to the secondary cylinder 2c, and the groove width Ws of the secondary pulley 2 (FIG. 1) decreases. The gear ratio control valve 16 controls the position of the port 16p in accordance with the solenoid supply pressure Pv supplied to the port 16e, the spring pressure of the spring 16sa, and the pressure difference between the control pressure Pva and the spring pressure of the spring 16sb. 8
When the control pressure Pva is high, the port 16a is pushed to the left as shown in the figure, and the port 16a is cut off from the port 16b and communicated with the discharge port 16x. As a result, the oil in the primary cylinder 1c is discharged from the port 16x, the groove width Wp of the primary pulley 1 is increased, and the speed ratio is controlled to the lower gear (lower).

When the control pressure Pva of the solenoid valve 8 decreases, the spool 16p of the speed ratio control valve 16 is pushed rightward in the drawing, the port 16a is cut off from the discharge port 16x, and is gradually communicated with the port 16b. The line pressure PL is also supplied to the primary cylinder 1c. The primary cylinder 1c has a larger pressure receiving area than the secondary cylinder 2c (FIG. 1), so that the pressing force of the primary cylinder 1c is larger than the pressing force of the secondary cylinder 2c, and as a result, the groove width Wp of the primary pulley 1
Is smaller, the groove width Ws of the secondary pulley 2 is wider, and the speed ratio is controlled to the higher gear side.

When the control pressure Pva of the solenoid valve 8 further decreases, the spring 16s pushes the spool 16p further rightward in the drawing, and the ports 16a and 16b are completely connected. Thereby, as shown in FIG. 3, the groove width Wp of the primary pulley 1 is minimum, and the groove width Ws of the secondary pulley 2 is
Is maximized, and the speed ratio becomes an overdrive state. Now, suppose that the solenoid valve 8 is abnormal, for example, disconnected and closed when the manual valve 9 is running at the D position. When the solenoid valve 8 closes, the control pressure P
When va becomes 0, the spool 16p of the speed ratio control valve 16 is pushed rightward in the drawing, the port 16a is communicated with the port 16b, and the speed ratio is controlled to the high speed side (overdrive side). . As a result, engine overspeed is prevented even during high-speed running. On the other hand, the regulator valve 15 is supplied with a control pressure Pvb corresponding to the vehicle speed from the solenoid valve 17 by an electronic control device, and regulates the pressure to a line pressure PL corresponding to the control pressure Pvb. Therefore, the line pressure PL required for traveling is secured.

When the solenoid valve 8 is closed and the control pressure Pv
When a becomes 0, the spool 7p of the shift limiting valve 7 is pushed rightward in the figure by the spring 7s, and the ports 7a and 7b are communicated as shown in FIG. In this state,
When the manual valve 9 is operated from the position D to the position L, for example, the clutch supply pressure Pc is supplied from the port 9b to the port 7b through the one-way valve 13, and
Through a, it is supplied to the port 15d of the regulator valve 15 and the port 16d of the speed ratio control valve 16.

The regulator valve 15 has a port 15d
When the clutch supply pressure Pc is supplied to the spool 15p '
Is pushed to the left, the spring 15sb is compressed to increase the spring pressure, and the spool 15p is pushed to the left as shown in FIG. 6, and the port 15b is moved to the port 15xp,
It is cut off from the discharge port 15x, and the line pressure PL increases. Further, the gear ratio control valve 16 controls the clutch supply pressure P
When c is supplied, the spool 16p 'is pushed to the left,
As a result, the spring 16sb is compressed to increase the spring pressure, and the spool 16p is pushed to the left, and the port 16
a is shut off from the port 16b and the discharge port 16
x.

As a result, the oil of the primary cylinder 1c is discharged from the discharge port 16x of the speed ratio control valve 16, and the groove width Wp of the primary pulley 1 (FIG. 1) becomes maximum. On the other hand, a high line pressure P is applied to the secondary cylinder 2c.
L is supplied, and the groove width Ws of the secondary pulley 2 is minimized. As a result, the speed ratio is controlled to a low gear. Also when the manual valve 9 is operated to the R position, the gear ratio is controlled to the lower gear as described above.

As described above, even when the manual valve 9 is running at the D position, if the manual valve 9 is operated to the L position, the speed ratio of the low gear is obtained, and therefore, the startability and the climbability are secured. Similarly, by moving the manual valve 9 to the R position, the reverse is ensured. Moreover, when the manual valve 9 is operated to the L position or the R position, the line pressure PL is increased, and the slip of the belt is prevented.

When the electronic control unit fails and both solenoid valves 8 and 17 are deenergized, the gear ratio is shifted to the high speed side as described above, and the regulator valve 15 is moved to the spool 15p. Is spring 15sa
Is pushed to the left in the figure, and the port 15a is
xp, and the line pressure PL decreases accordingly.
Therefore, when traveling on the high speed side, the line pressure is reduced, and an excessive load is not applied to the belt 3.

[0029]

As described above, according to the present invention, when an abnormality occurs in an electronic control device such as a solenoid valve for controlling a transmission, the speed ratio becomes higher and the line pressure becomes lower. In addition, an excessive load is prevented from being applied to the belt when traveling on the high speed side, and the durability of the belt is not impaired. Also, when the gear ratio on the low speed side is selected, the line pressure is increased, so that the startability and climbing performance are secured, and even when the input torque is large, the belt does not slip and sufficient climbing performance is secured, There are excellent effects such as preventing the durability of the belt from being impaired.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a belt-type continuously variable transmission.

FIG. 2 is a perspective view showing a state of a low-speed side (low side) of the transmission of FIG. 1;

FIG. 3 is a high-speed side (overdrive side) of the transmission of FIG. 1;
It is a perspective view which shows the state of.

FIG. 4 is a hydraulic circuit diagram of a conventional control device of the belt-type continuously variable transmission of FIG.

FIG. 5 is a hydraulic circuit diagram showing one embodiment of a control device for a belt-type continuously variable transmission according to the present invention.

6 is a diagram showing a state when a solenoid valve that controls a gear ratio control valve of the hydraulic circuit in FIG. 5 is abnormal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Primary pulley 1c Primary cylinder 2 Secondary pulley 2c Secondary cylinder 3 Belt 4 Hydraulic control device 5 Hydraulic pump 7 Shift control valve 9 Manual valve 13, 14 One-way valve 15 Regulator valve 16 Gear ratio control valve 8, 17 Solenoid valve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 59/00-61 / 12,61 / 16-61/2 4,63 / 40-63/48 B60K 41 / 00-41/28

Claims (1)

(57) [Claims] 1. A belt-type continuously variable transmission in which a belt is wound between a primary pulley and a secondary pulley provided on an input shaft and an output shaft, and the groove width of each pulley is relatively changed by hydraulic pressure to change the speed. A gear ratio control valve that controls the hydraulic pressure of each of the pulleys to shift the transmission to a low speed side when the supplied control oil pressure is high, and a line pressure supplied to the transmission when the supplied control oil pressure is low. A regulator valve to be set is interposed between the manual valve and the speed ratio control valve and the regulator valve. The valve is opened when the supplied control oil pressure is low, and when the manual valve is at a specific position, a predetermined pressure is applied from the manual valve. The hydraulic pressure is supplied to the speed ratio control valve and the regulator valve to shift the speed ratio control valve to the lower speed side. A first regulator that regulates the regulator valve to a high line pressure and supplies a control hydraulic pressure to the transmission ratio control valve and the transmission restriction valve that is closed when the control hydraulic pressure is high; And a second control valve for supplying a control oil pressure to the regulator valve in accordance with a driving state of the vehicle.