JP3304804B2 - Transmission 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 an improvement in a shift control device for a V-belt type continuously variable transmission.

[0002]

2. Description of the Related Art As a continuously variable transmission mounted on a vehicle,
A V-belt type is conventionally known, for example, Japanese Patent Application No. 8-105467 proposed by the present applicant.

[0003] This is provided with a pair of variable pulleys on an input side and an output side whose contact pulley width with a V-belt of a continuously variable transmission is variably controlled based on oil pressure, and drives a movable conical plate of the input pulley. The gear ratio is continuously changed by changing the oil pressure supplied to the piston chamber. As shown in FIG. 9, a shift control valve for adjusting the oil pressure is provided with an input pulley piston chamber (not shown). It is composed of a spool valve for controlling the line pressure or the amount of communication with the drain.

In FIG. 9, a shift control valve 2 accommodates an axially displaceable spool 5 on the inner periphery of a sleeve 10, and the spool 5 is biased by a spring 9 'from the left side in the figure. The right end in the drawing is urged by the solenoid 4, and the thrust of the solenoid 4 is increased against the spring 9 ', so that the spool 5 moves to the left in the drawing, and the minimum thrust F0 in FIG. The displacement is made from the position (displacement X = 0) to the position of the maximum thrust (displacement) in FIG.

The sleeve 10 of the shift control valve 2 has a line pressure port 2a communicating with a line pressure circuit and a piston pressure port 2 communicating with an input pulley piston chamber (not shown).
b and the drain port 2c open at predetermined positions facing the spool 5, respectively. The lands 5a, 5b, and 5c are formed on the spool 5 at predetermined intervals from the left side in the figure.

The shift control valve 2 shifts the spool 5 in response to the thrust of the solenoid 4 against the spring 9 'to supply and discharge hydraulic oil to the piston pressure port 2b, thereby changing the speed of the continuously variable transmission. The ratio is adjusted, and the spring constant of the spring 9 ', that is, the relationship between the load F (= thrust of the solenoid 4) and the displacement X is set to a predetermined linear characteristic as shown in FIG. The control characteristics of valve 2 are:
As shown in FIG.

When the solenoid 4 is not operating, the spool 5 is urged by a spring 9 'to
Most contracted position of (A), i.e. the displacement amounts X = 0, is in the load = the initial value F0, the minimum thrust position of FIG. 11 in the section C _1.

In this position, the lands 5a and 5b block the drain port 2c and the line pressure port 2a, respectively, and the pressure oil in the input pulley piston chamber is sealed, so that a predetermined gear ratio is maintained.

When the extension drive of the solenoid 4 is started, the spool 5 is displaced to the left in FIG. 9A from FIG. 9A, and the oil passage between the lands 5a and 5b is formed as shown in FIG. 9B. The piston pressure port 2b and the drain port 2c communicate with each other via the
And communicating the amount of the drain port 2c (opening area of the port) is changed, communication amount increases according to the displacement of the spool 5 enters the section B ₁ in FIG. 11, further, the displacement of the spool 5 =
At the time of X1, the flow rate from the input pulley piston chamber 20 is equal to the maximum communication amount Dma on the downshift side shown in FIG.
x, and the load applied to the spool 5 (= the thrust of the solenoid 4, hereinafter referred to as thrust F) is F1 'as shown in FIG.

When the spool 5 is further displaced and enters the signal use range A 'in FIG. 11, the amount of communication on the downshift side gradually decreases to the neutral position N shown in FIG. 9C. In this neutral position, since the land 5b seals the piston pressure port 2b, a predetermined gear ratio is maintained similarly to the minimum thrust position, the displacement of the spool 5 is X2, and the thrust applied to the spool 5 at this time is X2. F2.

Further, when the solenoid 4 drives the spool 5 to the left in the figure, the line pressure port 2a and the piston pressure port 2b communicate with each other through an oil passage between the lands 5b and 5c.
Pressure oil is supplied to the input pulley piston chamber, and the upshift shown in FIG. 9D is performed. That is, according to the displacement of the spool 5 to the left in the drawing, the communication amount between the line pressure port 2a and the piston pressure port 2b is changed according to the displacement of the spool 5 in the signal use range A 'of FIG. When the displacement increases and the displacement of the spool 5 is X3, the maximum flow rate Umax on the upshift side is reached as shown in FIG. At this time, the spool 5
Of the spool 5 is X3 '
Is directly proportional to the thrust F.

[0012] Furthermore spool 5 is displaced into the section B ₂ in FIG. 11, the communication amount to the upshift side, gradually decreases according to the displacement of the spool 5 in the opposite. Then, further into the interval C ₂ in FIG. 11, is blocked again line pressure port 2a and the drain port 2c Portland 5b, by 5c, maximum thrust position shown in the thrust of the solenoid 4 is maximized FIG 9 (E) ( Operating state). At this maximum thrust position, supply and discharge of hydraulic oil to and from the piston pressure port 2b are not performed, and a predetermined gear ratio is maintained similarly to the minimum thrust position.

In FIG. 11, among the signals output by the control unit for controlling the solenoid 4, the signal value to the solenoid 4 at which the spool 5 is at the neutral position N is defined as a neutral value, and a predetermined range including the neutral value is used. (Section N in the figure
In the case of 1), the operating oil is sealed in the input pulley piston chamber, so that no shift is performed.

A control unit that determines a target gear ratio in accordance with the driving state of the vehicle by the above-described shift control valve 2 sends an operation amount (for example, a command value for duty control or the like) to an actuator such as a solenoid 4. Then, the actual speed ratio is made to coincide with the target speed ratio.

Then, the control unit is as shown in FIG.
Of the signal output range, a signal is output in a section A ′ (signal use range) between the lower limit value Dmax and the upper limit value Umax,
When the solenoid 4 is in a non-operating state (at the time of minimum thrust) or a maximum operating state (at the time of maximum thrust), the piston pressure port 2b of the input pulley is sealed to prohibit supply and discharge of hydraulic oil.
When a failure occurs in the control unit or the solenoid 4, etc., stable feedback is ensured while avoiding the use of the area where the control gain is negative (diverging) while ensuring fail-safe by preventing abrupt shifting operation. Control (for example, PID control) is performed.

[0016]

However, in the above-mentioned conventional example, the flow rate characteristic of the shift control valve 2 is such that the control unit has a signal output range that excludes a region where the control gain is negative (divergence) in the signal output range. However, since the spring constant of the spring is set linearly, it is difficult to increase the ratio of the signal use range to the signal output possible range, and the input pulley piston chamber for the signal output value to an actuator such as a solenoid. The sensitivity of the flow rate to the air becomes large, and even if the change in the signal output value is small, the change in the flow rate becomes large, which is an obstacle to performing high-precision control.

The present invention has been made in view of the above problems, and has as its object to perform a shift control with high accuracy by enlarging a signal use range of a signal output possible range.

[0018]

According to a first aspect of the present invention, an input pulley and an output pulley in which a contact pulley width of a belt is variably controlled based on hydraulic pressure, and a pulley width is formed on the input / output pulley to change the pulley width. A piston chamber, line pressure supply means for supplying a predetermined line pressure to the piston chamber of the output pulley, and hydraulic oil to the piston chamber of the input pulley,
A shift control valve for supplying / discharging according to an amount of communication with one of the line pressure port and the drain port, an actuator for driving the shift control valve, and the actuator based on an operation amount calculated according to a driving state of the vehicle. Shift control means for driving the shift control valve, shift inhibition means for inhibiting supply and discharge of hydraulic oil to the input pulley piston chamber when the actuator is in a non-operation state or a maximum operation state, A shift control device for a belt-type continuously variable transmission, comprising: an operation amount restricting unit that restricts the operation amount so as not to exceed predetermined upper and lower limits. An elastic member for urging the spool against the thrust of the actuator is provided at the other end, and an elastic member is provided at one end of the spool. Wood is to the input pulley piston chamber
Spring constant in the displacement range of the spool that allows the supply and discharge of hydraulic fluid
Higher, and lower the spring constant in other areas.
You.

According to a second aspect of the present invention, in the first aspect, the elastic member is configured to reduce the displacement of the spool.
From the maximum displacement on the shift side to the maximum
The spring constant is set high in the displacement range up to the displacement amount where the flow rate becomes large.
And set the spring constant low in other areas .

In a third aspect of the present invention based on the second aspect, the elastic member has a first displacement at which the flow rate to the input pulley piston chamber becomes the maximum flow rate on the downshift or upshift side from the initial stage of the displacement of the spool. Beyond the flow rate and the neutral position, the flow rate is also on the upshift or downshift side
A first elastic member having a linear characteristic for urging the spool in a section up to a third displacement amount at which the maximum flow rate is obtained, and a spool extending in a section from the first displacement amount to a neutral position and up to a third displacement amount; A second elastic member having a linear characteristic for urging, and a third elastic member having a linear characteristic for urging the spool via the first and second elastic members from the third displacement amount to the maximum displacement position of the spool; An interposition member interposed between the first and second elastic members and the third elastic member and capable of abutting on one end of the spool with the third displacement amount or more; And a preload applying means for applying a preload equal to the urging force of the second elastic member, wherein the combined spring constant of the first and second elastic members is set to be larger than the first elastic member spring constant.

According to a fourth aspect of the present invention, in the third aspect, the preload is given to the third elastic member by the preload applying means in advance.

In a fifth aspect based on the third aspect, the preload applying means is interposed between the first and second elastic members and the third elastic member.
A piston that can abut one end of the spool with a displacement amount or more,
A constant pressure supply means for applying a hydraulic pressure equal to the urging force of the first and second elastic members at the third displacement amount to the piston.

[0023]

According to the first aspect of the present invention, the position of the spool is determined by the shift control valve in accordance with the operation amount of the shift control means and the biasing force of the elastic member opposing the thrust of the actuator. The elastic member is capable of supplying and discharging hydraulic oil to and from the input pulley piston chamber.
Set the spring constant high in the displacement area of the pool, and
Since the spring constant is set low in the range, the actuator can be quickly driven from the non-operating state or the maximum operating state of the actuator to a region where the supply and discharge of hydraulic oil to the input pulley piston chamber is possible, and the control gain is negative. It is possible to perform the shift control with higher precision than the conventional example by expanding the range of the upper limit value and the lower limit value of the operation amount for maintaining the control gain to be positive. Become.

According to a second aspect of the present invention, the elastic member includes a spoon.
Of the maximum flow rate on the downshift side
Displacement area up to the displacement amount at the maximum flow rate on the upshift side
To set the spring constant higher, and to lower the spring constant in other areas.
As a result, the actuator can be quickly driven from the non-operation state or the maximum operation state of the actuator to the area where hydraulic oil can be supplied to and discharged from the input pulley piston chamber, and the area where the control gain is negative is reduced. Therefore, the range of the upper limit value and the lower limit value of the operation amount for maintaining the control gain to be positive can be expanded, and the shift control can be performed with higher precision than the conventional example.

According to the third aspect of the present invention, of the first to third elastic members having linear characteristics, the combined spring constant of the first and second elastic members is set to be larger than the spring constant of the first elastic member. Since the spool is displaced according to the low spring constant in the section up to the first displacement and in the section exceeding the third displacement, the first displacement at which the flow to the input pulley piston chamber becomes the maximum on the downshift or upshift side. And the section up to the third displacement amount where the flow rate becomes the maximum flow rate on the upshift or downshift side beyond the neutral position, that is, the upper limit value and the lower limit value of the manipulated variable where the control gain is positive can be increased. Thus, it is possible to perform the shift control with higher precision than the conventional example.

According to the fourth aspect of the present invention, the preload for restricting the displacement of the third elastic member until the spool reaches the third displacement amount is applied to the third elastic member, so that the structure of the shift control valve can be simplified.

According to a fifth aspect of the present invention, a preload for regulating the displacement of the third elastic member until the spool reaches the third displacement amount is interposed between the first extending second elastic member and the third elastic member. Then, since it is performed by the piston which is urged by the constant pressure supply means, the spring constant of each elastic member can be set freely, and the degree of freedom in design can be improved.

[0028]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a shift control device of a V-belt type continuously variable transmission. A continuously variable transmission 17 includes an input pulley 1 connected to an engine (not shown) as a variable pulley.
6 and an output pulley 26 connected to a drive shaft, and these variable pulleys are connected by a V-belt 24.

The input pulley 16 has a fixed conical plate 22 which rotates integrally with a shaft connected to an engine (not shown).
The movable conical plate 18 is disposed opposite to the fixed conical plate 22 to form a V-shaped pulley groove, and can be displaced in the axial direction according to the hydraulic pressure acting on the input pulley piston chamber 20 from the transmission control valve 2. Consists of

On the other hand, the output pulley 26 has a fixed conical plate 30 which rotates integrally with a shaft connected to the axle, and is arranged to face the fixed conical plate 30 to form a V-shaped pulley groove. It is composed of a movable conical plate 34 that can be displaced in the axial direction according to the line pressure from the hydraulic control unit 3 acting on the pulley piston chamber 32.

The speed change control for changing the widths of the V-shaped pulley grooves of the input pulley 16 and the output pulley 26 is performed by a command from the CVT control unit 1 to supply / discharge hydraulic oil to / from the input pulley piston chamber 20. This is performed by the shift control valve 2 driven in accordance with.

The CVT control unit 1 mainly composed of a microcomputer or the like operates a deviation between the target gear ratio and the actual gear ratio so that the target gear ratio calculated based on the driving state of the vehicle matches the actual gear ratio. Is instructed to the solenoid 4 in accordance with the operation amount.

For example, the input rotation speed Nin and the output rotation speed Nout (∝ vehicle speed VSP) read from the input shaft speed sensor 6 and the output shaft speed sensor 7 of the continuously variable transmission 17, and the throttle according to the driver's operation. While reading the opening degree TVO and the signal (shift mode and the like) from the inhibitor switch 8 and reading the engine speed Ne from an engine control unit (not shown), the target speed ratio according to the driving state of the vehicle is calculated, After the actual speed ratio of the transmission 17 is obtained, a command value, for example, a duty ratio, to the solenoid 4 is sent out by feedback control or the like in accordance with a deviation between the actual speed ratio and the target speed ratio.

That is, the CVT control unit 1
The hydraulic pressure applied to the input pulley piston chamber 20 is controlled by a hydraulic control unit 3 including a solenoid 4 acting as an actuator responding to a command from the controller and a shift control valve 2 driven by the solenoid 4, and the like.
Further, the hydraulic control unit 3 is provided with a line pressure supply means (not shown),
And a predetermined line pressure is supplied to the transmission control valve 2.

FIG. 2 shows the speed change control valve 2. A line pressure port 2a communicating with a line pressure circuit and a piston communicating with an input pulley piston chamber (not shown) are provided on the inner periphery of a sleeve 10 of the speed change control valve 2. The pressure port 2b and the drain port 2c open at predetermined positions facing the spool 5, respectively. The lands 5a, 5b, and 5c are formed on the spool 5 at predetermined intervals from the left side in the figure.

A spring 9 is interposed between the left end of the spool 5 and the bottom 10L of the sleeve 10 in FIG.
While the spool 5 is urged to the right in the drawing, the retractable solenoid 4 contacts the right end of the spool 5 in the drawing.

The shift control valve 2 shifts the spool 5 in accordance with the thrust of the solenoid 4 against the spring 9 to supply and discharge hydraulic oil to the piston pressure port 2b, thereby changing the speed of the continuously variable transmission 17. The spring 9 is constituted by a non-linear spring, and has a spring constant, that is,
Load F (= thrust of solenoid 4) and displacement X of spool 5
Is set in a predetermined non-linear manner as shown in FIG. 3, for example.

As shown in FIG. 3, the spring constant of the spring 9 having the non-linear characteristic is set low in the initial compression region up to the spool displacement (hereinafter simply referred to as displacement) X1, and the displacement X1 (first displacement) is set. 1), the spring constant is set high until the displacement X3 at the end of compression.
In the region at the end of compression exceeding (the third displacement amount), the displacement X1
The spring constant is set low similarly to the initial compression region up to. That is, assuming that the spring constant in a region smaller than the displacement X1 and larger than the displacement X3 is K1, and the spring constant not less than the displacement X1 and not more than X3 is K2, K1 <K2 is set.

The operation will be described next.

As shown in FIG. 3, the spring constant of the spring 9 is smaller than the displacement X1 at the initial compression and the displacement X3 at the final compression.
While the spring constant of the region exceeding
Since the spring constant of X3 or less is set high, the flow characteristic of the shift control valve 2 is as shown in FIG.

When the solenoid 4 is in a non-operating state (minimum thrust F
0), the spool 5 is urged by the spring 9 to be in the most contracted position of FIG. 9A shown in the prior art, ie, the displacement X = 0 and the load = initial value F0. the minimum thrust position of the section C _1.

In this position, the lands 5a and 5b shut off the drain port 2c and the line pressure port 2a, respectively, and the pressure oil in the input pulley piston chamber is sealed so that a predetermined gear ratio is maintained (gear prohibition). means).

When the extension drive of the solenoid 4 is started, the spool 5 is moved from FIG.
Is displaced to the left in the figure, and the land 5 is displaced as shown in FIG.
a, piston pressure port 2b and the drain port 2c via the oil passage between 5b communicates enters in Figure 4 in the section B _1, and communicating the amount increases according to the displacement of the spool 5, further spool 5 When the displacement of X is X1, the flow rate from the input pulley piston chamber 20 becomes the maximum communication amount Dmax on the downshift side shown in FIG.

At this time, the thrust F of the solenoid 4 applied to the spool 5 is F1, and the thrust F1 of the solenoid 4 is from the displacement X = 0 to the displacement X1 at which the maximum communication amount Dmax on the downshift side is obtained. Becomes smaller than F1 ′ of the above.

Further, when the spool 5 is displaced and enters the signal use range A (between the upper limit value and the lower limit value of the operation amount) in FIG.
The communication amount on the downshift side gradually decreases to the neutral position N shown in FIG. 9C shown in the conventional example.

In this neutral position, since the land 5b seals the piston pressure port 2b, a predetermined gear ratio is maintained similarly to the minimum thrust position, and the displacement of the spool 5 is X2
And the thrust applied to the spool 5 at this time is F2.

From this neutral position N, the solenoid 4
Drives the spool 5 to the left in the drawing, the lands 5b, 5
The line pressure port 2a and the piston pressure port 2b communicate with each other via the oil passage between the cylinders c, and the pressurized oil is supplied to the input pulley piston chamber to be in the upshift position shown in FIG. .

That is, according to the displacement of the spool 5 to the left in the drawing, the line pressure port 2a and the piston pressure port 2b
4, the communication amount increases in accordance with the displacement of the spool 5 in the signal use range A in FIG. 4, and when the displacement of the spool 5 = X3, as shown in FIG. U
max. At this time, the thrust applied to the spool 5 is F3
And the signal use range A (displacement X1 to X3, thrust F1
In the section from F3 to F3, the displacement X of the spool 5 is directly proportional to the thrust F according to the spring constant K2 of the spring 9.

Then, the maximum flow rate Uma on the upshift side
The thrust F3 at the displacement X3 of the spool 5, which is x, is set larger than F3 'of the conventional example, that is, located at the maximum thrust side of the solenoid 4, so that the signal use range A is changed to the signal use range of the conventional example. It can be enlarged as compared with the range A '.

Further, when the spool 5 is displaced, the section B shown in FIG.
_{In step 2} , the amount of communication to the upshift side gradually decreases in accordance with the displacement of the spool 5. Then, further into the interval C ₂ in FIG. 4, it is blocked again line pressure port 2a and the drain port 2c Portland 5b, by 5c,
When the thrust of the solenoid 4 reaches the maximum F4, the maximum thrust position X4 (maximum operation state) shown in FIG. 4 and the conventional example shown in FIG. At the maximum thrust position X4, supply and discharge of hydraulic oil to and from the piston pressure port 2b are not performed, and a predetermined gear ratio is maintained similarly to the minimum thrust position X0.

The control unit 1 which determines the target gear ratio according to the driving state of the vehicle by the above-described gearshift control valve 2 sends an operation amount (for example, a command value for duty control or the like) to an actuator such as the solenoid 4. The transmission is performed in the signal use range A where the control gain is positive, and the actual speed ratio is made to coincide with the target speed ratio.

Then, the CVT control unit 1
Outputs a signal in a section A (signal use range) between the lower limit value Dmax and the upper limit value Umax in the signal output range of FIG. 4, while the solenoid 4 is in a non-operating state (at a minimum thrust) or a maximum operation. In the state (at the time of maximum thrust), the piston pressure port 2b of the input pulley is sealed to prohibit the supply and discharge of hydraulic oil, so that when a failure occurs in the CVT control unit 1, the solenoid 4, etc. Thus, stable feedback control (for example, PID control) is performed while preventing the occurrence of a shift operation and ensuring fail-safe while avoiding use of a region where the control gain is negative (diverging).

By setting the spring constant of the spring 9 against the thrust F of the solenoid 4 to be small at the beginning and end of compression and large at other sections, the sections B ₁ and B _{2 in} which the control gains are negative can be set. On the other hand, the signal use range A in which the control gain is positive can be expanded as compared with the signal use range A 'of the conventional example, and the input pulley for the signal output value to the solenoid 4 in the signal use range A can be reduced. It is possible to reduce the sensitivity of the flow rate to the piston chamber, and when the change in the signal output value is small, the change in the flow rate is also small, so that a more accurate shift control can be performed as compared with the conventional example. You can.

FIGS. 5 to 7 show a second embodiment, in which three springs 9a, 9b, 9c and a collar 11 having different spring constants are provided in place of the spring 9 of the first embodiment. Is similar to that of the first embodiment.

Spring 9a (first elastic member), 9b
The (second elastic member) is provided between the collar 11 as an interposition member and a land 5 a of the spool 5, which is provided with a through hole in the center and is slidably supported on the inner periphery of the sleeve 10. A spring 9c is interposed between the bottom 10A of the sleeve 10 and the collar 11.

Here, the spring 9a is constituted by a linear spring having a spring constant K1, and the displacement of the spool 5 is changed from X0 (minimum thrust position) to X3 (upshift side maximum communication amount position) as in the first embodiment. Acts in the range.

On the other hand, the spring 9b coaxially arranged on the inner periphery of the spring 9a is constituted by a linear spring having a spring constant K2, and the displacement of the spool 5 is similarly X1 (downshift-side maximum communication amount position) to X3. Acts in the range.

The spring 9c (third elastic member) between the bottom 10A of the sleeve 10 and the collar 11 is constituted by a linear spring having a spring constant K3. The spring 9c applies a preload F3, and the displacement of the spool 5 is reduced. If it is less than X3, the displacement of the collar 11 is restricted, while it acts in the range of displacements X3 to X4 (maximum thrust position).

As shown in FIGS. 6 and 7, when the displacement of the spool 5 is between the minimum thrust position X0 and the maximum communication position X1 on the downshift side, the spool 5 is biased against the thrust F of the solenoid 4. The reaction force of the spring is
Therefore, the reaction force = K1 × X ≦ F1.

Next, the maximum communication amount position X1 on the downshift side.
In the signal use range A from the neutral position N to the maximum communication amount position X3 on the upshift side with respect to the neutral position N, the reaction force of the spring that biases the spool 5 against the thrust F of the solenoid 4 is the spring 9a. And the spring 9b, the reaction force = K1 × X + K2 (X−X1) ≦ F3, and the reaction force is a value corresponding to the thrusts F1 to F3.

Then, the thrust of the solenoid becomes F3, and the spool 5 moves to the maximum communication position X3 on the upshift side.
6D, the left end of the spool 5 in the drawing comes into contact with the collar 11 as shown in FIG. 6D, and when the solenoid 4 is further driven to extend to the maximum thrust position (X4), the reaction force of the spring is exerted in the section between X3 and X4. Changes according to only the spring constant K3 of the spring 9c as shown in FIG. 7 (C), and the reaction force = K1 × X + K2 (X3-X1) + K3 × (XX)
3) Here, since the preload of the spring 9c is F3, this formula is as follows: Reaction force = F3 + K3 × (X−X3)

Therefore, by setting the spring constants K1 and K3 of the springs 9a and 9c to be equal,
The relationship between the biasing force of the springs 9a to 9c and the displacement is the first type.
As in FIG. 3 of the embodiment, the control characteristics of the shift control valve 2 can be made the same as in FIG. 4, and the signal use range A can be expanded as compared with the conventional example.

FIG. 8 shows a third embodiment. In place of the collar 11 of the second embodiment, a free piston 12 giving a preload = F3 and a free piston 12
Is provided with a constant pressure port 14 for supplying oil pressure and an oil chamber 13 while the preload of the spring 9c is set to 0.
Other configurations are the same as those of the second embodiment.

The inner circumference of the sleeve 10 and the free piston 12
An oil chamber 13 for urging the free piston 12 toward the spool 5 is defined between the outer circumferences of the oil chamber 1 and the oil chamber 1.
A constant pressure port 14 for guiding a predetermined oil pressure, for example, a constant pressure such that the preload of the free piston 12 becomes equal to F3, is formed in 3 and communicates with a constant pressure supply means (not shown).

In this case, up to the displacement X3 and the thrust F3 at which the spool 5 has the maximum communication amount on the upshift side, the above-mentioned second position is satisfied.
When the thrust of the solenoid 4 is increased toward the maximum thrust F4 exceeding F3, the free piston 12 is pressed by the end of the spool 5 and displaces leftward in the drawing, and the spring 9c is actuated. The spring is displaced to the maximum displacement position X4 with the characteristic according to the spring constant K3, and the resultant force of each spring has the same characteristic as that of FIG.

Also in this case, the spring 9a
By setting the spring constants K1 and K3 equal to each other and 9c, the relationship between the biasing force and the displacement of the springs 9a to 9c becomes the same as that in FIG. 3 of the first embodiment, and the control characteristics of the transmission control valve 2 are shown. 4 and the signal use range A can be expanded as compared with the conventional example. In addition, since the spring 9c does not need to be preloaded, the design of the springs 9a to 9c can be improved. The degree of freedom can be expanded.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a shift control device of a belt-type continuously variable transmission, showing an embodiment of the present invention.

FIG. 2 is a sectional view of the transmission control valve.

FIG. 3 is a graph showing a relationship between a load and a displacement of a spring of a shift control valve.

FIG. 4 is a graph showing flow rate characteristics of a shift control valve, showing a thrust of a solenoid and a communication amount of the shift control valve.

FIG. 5 is a sectional view of a shift control valve according to a second embodiment.

FIG. 6 is a schematic diagram showing the operation of the shift control valve, where (A) shows the position of the spool when the thrust of the solenoid is minimum,
(B) is the position of the spool where the continuously variable transmission has the maximum flow rate on the downshift side, (C) is the neutral position of the spool similarly, and (D) is the position of the spool where the maximum flow rate is also on the upshift side. (E) shows the position of the spool when the thrust of the solenoid is maximum.

FIG. 7 is a schematic diagram showing the operation of the spring according to the displacement section of the spool. FIG. 7 (A) shows the section where the thrust of the solenoid is minimum to the maximum amount of communication on the downshift side.
(B) shows a section where the maximum flow rate is reached on the upshift side from the maximum flow rate on the downshift side to the neutral position, and (C) shows a section where the thrust of the solenoid becomes maximum from the position where the maximum flow rate is reached on the upshift side. Shown respectively.

FIG. 8 is a sectional view of a transmission control valve according to a third embodiment.

9A and 9B are schematic diagrams showing a conventional example and showing the operation of a shift control valve, wherein FIG. 9A shows the position of the spool when the thrust of the solenoid is at a minimum, and FIG. 9B shows the continuously variable transmission in a downshift state. (C) also shows the neutral position of the spool, (D) shows the spool position in the upshift state, and (E) shows the spool position when the thrust of the solenoid is maximum.

FIG. 10 is a graph showing a relationship between load and displacement of a spring of a shift control valve, similarly showing a conventional example.

FIG. 11 is a graph showing the flow rate characteristics of the shift control valve, showing the thrust of the solenoid and the communication amount of the shift control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CVT control unit 2 Shift control valve 2a Line pressure port 2b Piston pressure port 2c Drain port 3 Hydraulic control valve 4 Solenoid 5 Spool 5a, 5b, 5c Land 6 Input speed sensor 7 Output speed sensor 9 Spring 9a-9c Spring 10 Sleeve 11 Collar 12 Free piston 13 Oil chamber 14 Constant pressure port 16 Input pulley 17 Continuously variable transmission 18 Movable conical plate 22 Fixed conical plate 20 Input pulley piston chamber 24 V belt 26 Output pulley 30 Fixed conical plate 32 Output pulley piston chamber 34 Movable conical plate

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (5)

(57) [Claims] 1. An input pulley and an output pulley in which a contact pulley width of a belt is variably controlled based on a hydraulic pressure, a piston chamber formed on each of the input / output pulleys to change a pulley width, and a piston chamber of the output pulley. A line pressure supply means for supplying a predetermined line pressure to the line, a shift control valve for supplying and discharging hydraulic oil to the piston chamber of the input pulley according to a communication amount with one of a line pressure port or a drain port, An actuator for driving the shift control valve; a shift control means for driving the actuator based on an operation amount calculated according to a driving state of the vehicle; and a shift control valve formed in the shift control valve so that the actuator is in a non-operating state or A shift prohibiting unit for prohibiting supply and discharge of hydraulic oil to and from the input pulley piston chamber in a maximum operation state; A shift control valve for a belt-type continuously variable transmission, the shift control valve including a slidable spool, and one end of the spool. While connected to the actuator,
The other end of the elastic member against the thrust of the actuator biases the spool provided in, the elastic member, the input pool
Spool displacement capable of supplying and discharging hydraulic oil to the re-piston chamber
Set the spring constant high in the region and set the spring constant in other regions
A shift control device for a belt-type continuously variable transmission, wherein the number is set low . 2. The elastic member according to claim 1 , wherein the displacement of the spool is reduced.
Upshift from the maximum flow rate displacement on the downshift side
The spring constant in the displacement range up to the displacement amount where the maximum flow rate is
The shift control device for a belt-type continuously variable transmission according to claim 1 , wherein the spring constant is set high and the spring constant is set low in other regions . 3. The elastic member according to claim 1, wherein the flow rate to the input pulley piston chamber from the initial stage of the displacement of the spool exceeds the first displacement amount and the neutral position at which the maximum flow rate is at the downshift or upshift side, and the flow rate is similarly upshifted. Alternatively, the first characteristic of the linear characteristic that biases the spool in a section up to a third displacement amount at which the maximum flow rate is obtained on the downshift side.
An elastic member, a second elastic member having a linear characteristic for urging the spool in a section from the first displacement amount to a third position beyond the neutral position, and a maximum displacement position of the spool from the third displacement amount. A third elastic member having a linear characteristic for urging the spool through the first and second elastic members, and a third elastic member interposed between the first and second elastic members and the third elastic member. An interposition member capable of abutting on one end of the spool at a third displacement amount or more, and a preload applying means for applying a preload equal to the urging force of the first and second elastic members at the third displacement amount; The shift control device for a belt-type continuously variable transmission according to claim 2, wherein a combined spring constant of the first and second elastic members is set to be larger than the first elastic member spring constant. 4. The shift control device for a belt-type continuously variable transmission according to claim 3, wherein the preload applying unit is a preload applied to a third elastic member in advance. 5. The preload applying means is interposed between first and second elastic members and a third elastic member,
The piston includes a piston capable of abutting on one end of the spool when the displacement amount is equal to or greater than the third displacement amount, and constant pressure supply means for applying a hydraulic pressure equal to the urging force of the first and second elastic members at the third displacement amount to the piston. The speed change control device for a belt-type continuously variable transmission according to claim 3, wherein: