JP3520588B2 - Line pressure control device for V-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 line pressure control device for appropriately controlling a line pressure which is important for speed change control of a V-belt type continuously variable transmission, especially in a no-load state of a prime mover.

[0002]

2. Description of the Related Art A V-belt type continuously variable transmission is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-105347, wherein one of a pair of pulleys around which a V-belt is wound (usually a secondary pulley). The line pressure is applied to the movable flange, and the shift control pressure obtained by reducing the line pressure by the shift control valve is applied to the movable flange of the other pulley (usually the primary pulley). It is usual that the speed change ratio is controlled steplessly by adjusting the pressure difference between the speed change ratio and the speed change control pressure to a value corresponding to the required speed change ratio.

As is clear from the above description, the line pressure is involved in the tension of the V-belt that is stretched between the pulleys, and increasing the line pressure more than necessary makes the tension of the V-belt excessive. If the line pressure is low and the tension of the V-belt is too low, not only will the transmission efficiency be reduced due to slippage, but also in this case the V-belt will wear out and become durable. Sex is lowered.

Therefore, in general, when the line pressure is generated by reducing the pump pressure, it is customary to control the line pressure to a minimum value according to the input torque for each gear ratio. Even if the line pressure is high or low from such a controlled value, the durability of the V-belt is adversely affected. However, during coasting with the prime mover in the preceding stage of the V-belt type continuously variable transmission in an unloaded state (release of the accelerator pedal), the input torque may become negative in the opposite direction due to engine braking,
Since it is difficult to detect the input torque, it seems that the input torque is adopted in the V-belt type continuously variable transmission mounted on the K11 type vehicle “March” developed by the applicant of the present invention and on the market (for details, see 1992). It was common to maintain a high constant line pressure corresponding to the expected maximum reverse torque, according to the same vehicle manual issued in January of the year).

[0005]

However, in the conventional line pressure control device for the V-belt type continuously variable transmission represented by the one described in the above document, the line pressure in the unloaded state is
As described above, the line pressure control in the no-load condition is inaccurate and often too high because the value is maintained at a constant high value that does not become insufficient at any time, so engine braking is effective. This has caused problems that the driver feels uncomfortable, the operating oil temperature of the continuously variable transmission becomes overheated, and above all, the durability of the V-belt is deteriorated.

According to the present invention, the transmission input torque in the unloaded state is calculated and the line pressure in the unloaded state is controlled accordingly, so that the line pressure is appropriately controlled in the unloaded state and in the sill. The purpose is to solve the above problems.

[0007]

For this purpose, a line pressure control device for a V-belt type continuously variable transmission according to the first invention is provided with a V
Of the pair of pulleys around which the belt is wound, the line pressure is applied to the movable flange of one pulley, and the gear shift control pressure obtained by reducing the line pressure is applied to the movable flange of the other pulley. In the V-belt type continuously variable transmission in which the speed ratio is controlled steplessly by the differential pressure between the shift control pressure and the line pressure, the load condition of the prime mover before the continuously variable transmission is no load. No-load state detection means for detecting that, a prime mover speed detection means for detecting the number of rotations of the prime mover, during the detection of the no-load state by the no-load state detection means, the detected number of revolutions of the prime mover Based on this, the negative torque of the prime mover is calculated such that the absolute value increases as the detected prime mover speed increases over the entire range of the prime mover speed , and the negative torque of the prime mover is calculated from this torque.
In the range, the absolute value increases as the number of revolutions of the prime mover increases, and a no-load input torque calculation means for obtaining a negative no-load input torque of the transmission, and the line pressure, the negative pressure during detection of the no-load state. It is characterized by comprising no-load line pressure adjusting means for adjusting the pressure according to the negative torque of the prime mover by adjusting the pressure to a value corresponding to the no-load input torque.

The V-belt type continuously variable transmission according to the second invention
The line pressure control device of the
A gear ratio calculation means for calculating a ratio is added to the loadless load
The in-pressure adjusting means is not only the input torque without load,
Even when the no-load condition is being detected, even according to the calculated gear ratio.
Characterized by being configured to regulate the line pressure
Is.

Further, a V-belt type continuously variable transmission according to the third invention
The line pressure control device of the
Addition of centrifugal pressure calculation means to calculate the centrifugal pressure acting on
However, the unloaded line pressure adjustment means is
It is characterized in that the line pressure is reduced only by the pressure.
It is something.

[0010]

In the first invention, the V-belt type continuously variable transmission is
Power is transferred between a pair of pulleys via a belt.
At this time, one of the pair of pulleys is movable.
Apply line pressure to the flange to move the movable pulley of the other pulley.
In the lunge, this line pressure is reduced by the shift control valve.
By applying the obtained shift control pressure, the V-belt type
The gear transmission changes according to the differential pressure between the shift control pressure and the line pressure.
The speed ratio can be achieved steplessly. Therefore, the above
By determining the shift control pressure with the shift control valve,
The gear ratio can be obtained.

Here, the unloaded state detection means detects that the loaded state of the prime mover in the preceding stage of the continuously variable transmission is the unloaded state, and the prime mover rotation speed detection means detects the number of rotations of the prime mover. During detection of the no-load state by the no-load state detecting means, the no-load input torque calculating means, based on the detected number of revolutions of the prime mover , detects the number of revolutions of the prime mover detected over the entire range of the number of revolutions of the prime mover. It calculates the negative torque of prime mover absolute value higher numbers increases, this torque, the original
The negative no-load input torque of the transmission is obtained in which the absolute value increases as the prime mover speed increases over the entire range of the prime mover speed.
Then, the no-load line pressure adjusting means regulates the line pressure according to the negative torque of the prime mover by regulating the line pressure to a value corresponding to the negative no-load input torque during detection of the no-load state. .

Therefore, when the load is not applied and the line pressure is high ,
The control is appropriately performed according to the negative input torque in the motive speed range, and it is possible to eliminate the disadvantage of the conventional device in which the line pressure in the no-load state is often too high. Therefore, the above-mentioned problem frequently occurred in the conventional device, that is, the line pressure in a no-load state is too high, the engine brake is too effective and the driver feels uncomfortable, or the hydraulic oil of the continuously variable transmission is increased. The temperature may be overheated,
It is possible to avoid the problem that the durability of the V-belt is lowered.

Further, in the first aspect of the invention, when the no-load input torque calculating means obtains the negative torque of the prime mover which is the source of the no-load input torque, the prime mover rotation speed detected by the prime mover rotation speed detecting means is used as a basis. In addition, since it is decided to calculate the negative torque of the prime mover, the absolute value of which increases as the detected prime mover speed increases over the entire range of the prime mover speed. It will be closer to the actual value by considering it, and the no-load input torque obtained from this will be accurate, and the above-mentioned action effect of preventing the line pressure from becoming too high under no-load condition is further secured. It can be anything.

In the second aspect of the invention, the gear ratio calculating means calculates the currently selected gear ratio of the continuously variable transmission, and the no-load line pressure adjusting means calculates not only the no-load input torque but also the calculated gear change. The line pressure during the detection of the no-load state is adjusted according to the ratio. In this case, a value closer to a proper value line pressure just enough, the first shot Ming effect that controls the line pressure to the appropriate value in the unloaded state can be even more reliably.

In the third invention, the centrifugal pressure acting on the movable flange of the one pulley to which the line pressure is applied is calculated, and the no-load line pressure adjusting means reduces the line pressure by the calculated centrifugal pressure. To do. In this case, the influence of the centrifugal pressure can be eliminated to bring the line pressure closer to the required value, and the action and effect of the first invention or the second invention can be made more remarkable.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 exemplifies a line pressure control device for a V-belt type continuously variable transmission according to the present invention together with a gear shift control device. Reference numeral 1 denotes a primary pulley as an input pulley to which the rotation of an unillustrated engine (motor) is input. Reference numerals 2 and 3 respectively denote secondary pulleys as output pulleys that output rotation after shifting. A V-belt 3 is wound around the primary pulley 1 and the secondary pulley 2,
It is possible to change the transmission ratio between the pulleys, that is, the gear ratio in a stepless manner by changing the winding arc diameter of the V belt 3 with respect to 2.

Therefore, in the primary pulley 1, the movable flange 1b forming the pulley V groove facing the fixed flange 1a can be displaced in the axial direction, and the secondary pulley 2
Also, the movable flange 2b forming the pulley V groove facing the fixed flange 2a can be displaced in the axial direction. Then, the shift control pressure P _S is applied to the movable flange 1b in the direction toward the fixed flange 1a, and the line pressure P _L is applied to the movable flange 2b in the direction toward the fixed flange 2a, so that the shift control pressure P _S and the line It is assumed that the diameter of the circular arc around which the V-belt 3 is wound around the pulleys 1 and 2 is changed steplessly in accordance with the pressure difference from the pressure P _L to perform continuously variable transmission.

The line pressure control system for controlling the line pressure P _L will be described below.
A pressure regulator valve 12 for adjusting the hydraulic fluid from now on to a line pressure P _L; a pressure modifier valve 13 for supplying a line pressure control modifier pressure P _m to the pressure regulator valve; (A) A line pressure solenoid 14 for controlling the valve 13 and a pilot valve 15 for supplying a constant pressure P _C to the solenoid.

The pressure regulator valve 12, while leakage of hydraulic oil from the pressure source 11 to the circuit 16, also with a drain from the drain port 12 _a as required line pressure according to the modifier pressure P _m P _L Regulate to. The pilot valve 15 supplies a leakage oil from the circuit 16 in the constant pressure P _C to the line pressure solenoid 14, the line pressure solenoid 14 in the duty pressure P _D corresponding to a constant pressure P _C in the drive duty D modifier valve 13 Apply to. The modifier valve 13 makes the oil leaked from the circuit 16 a modifier pressure P _m according to the duty pressure P _D , and thus the drive duty D of the line pressure solenoid 14, and applies this to the pressure regulator valve 12 to apply the line pressure P _L. Contribute to the above control of. Therefore, the line pressure P _L can be controlled by adjusting the drive duty D of the line pressure solenoid 14, and the solenoid drive duty D is determined by the controller 17 as described later.

The controller 17 also performs gear shift control. For the gear shift control and the line pressure control, the controller 17 includes a throttle opening sensor (corresponding to a no-load state detecting means) for detecting the engine throttle opening TVO. Signal from the primary pulley 1 and the primary pulley rotation sensor 1 for detecting the rotation speed N _pri of the primary pulley 1.
9 signal, secondary pulley 2 speed (vehicle speed) N
A signal from a secondary pulley rotation sensor 20 that detects _sec and a signal from an engine rotation sensor (corresponding to a prime mover rotation speed detection means) 27 that detects an engine rotation speed N _e are input.

Next, the shift control system will be described. It comprises a shift control valve 21 for determining the shift control pressure P _S , a shift link 22, and a step motor 23. One end of the speed change link 22 is connected to a shifter 24 that is displaced together with the primary pulley movable flange 1b, the other end is connected to be driven by a step motor 23, and both ends are pivotally attached to a spool 21a of the speed change control valve 21. . Here, the shift control valve 2
Reference numeral 1 is for reducing the line pressure P _L from the circuit 25 to create the shift control pressure P _S in the circuit 26. When the spool 21a is raised in the drawing, the shift control pressure circuit 26 is set to the line pressure circuit 2
5, the shift control pressure P _S is increased, and the spool 21a
When it is lowered in the figure, the shift control pressure circuit 26 is connected to the drain port 21b to reduce the shift control pressure P _S , and the stroke of the spool 21a is controlled by the step motor 23 via the shift link 22. Then, the rotational position of the step motor 21 is determined by the controller 17, and the following shift control is executed accordingly.

In this shift control, the controller 17
For example, based on a map corresponding to the shift control characteristic shown in FIG. 2, the target input rotation speed N _i is calculated from the vehicle speed N _sec and the throttle opening TVO, and a shift command corresponding to this is input to the step motor 23. Emit. As a result, the step motor 23 comes to the rotational position as instructed, and the speed change link 2
2 is rotated around the shifter 24 to stroke the shift control valve spool 21a. As a result, the shift control valve 21
Connects the circuit 26 to the line pressure circuit 25 and the drain port 2
1b is deviated from the equilibrium position where the same degree of communication is made,
By changing the shift control pressure P _S and displacing the movable flanges 1b and 2b of the pulleys 1 and 2, the gear ratio is brought to the gear ratio corresponding to the target input speed N _i .

As the speed change progresses, the movable flange 1b of the primary pulley 1 rotates the speed change link 22 around the step motor 23 through the shifter 24 so as to return the speed change control valve spool 21a to the original stroke position.
When the speed change ratio reaches the speed change ratio corresponding to the target input rotation speed N _i , the speed change control valve 21 returns to the equilibrium position to end the speed change control, and the target speed change ratio can be maintained.

Note that the controller 17 has a configuration as shown in FIG. 3 for controlling the line pressure P _L , but it goes without saying that it may be configured to execute a flowchart for performing the same operation. The speed ratio calculator 31 calculates a speed ratio e of a torque converter (not shown) interposed between the engine and the primary pulley 1 as e =
Calculated by N _e / N _pri , the torque ratio calculation unit 32 retrieves the torque ratio t of the torque converter from the torque converter performance diagram illustrated in FIG.

The engine torque estimating section 33 is, for example, as shown in FIG.
Based on the engine performance diagram shown in, the engine speed Ne
Also, the engine torque Te is retrieved from the throttle opening TVO. With the engine torque estimation unit 33 described above
The input torque estimating unit 34 constituting the no-load input torque calculating means in the present invention is in the non-lockup state according to the presence / absence of the lockup signal L / U directly connecting the input / output elements of the torque converter. Then, the transmission input torque T _i is multiplied by the engine torque Te and the torque ratio t T _i = Te × t
Calculated by, engine torque Te at lockup
Is directly used as the transmission input torque T _i .

A gear ratio calculating section 3 corresponding to a gear ratio calculating means
5 is the transmission ratio i between the input and output pulleys of the continuously variable transmission i = N
_sec / N is calculated by _pri, the required line pressure calculating unit 36 based on the request line pressure characteristics as shown in FIG. 6, for example, the required line pressure P ₀ that corresponds to the gear ratios i for each transmission input torque T _i To search. Here, the centrifugal pressure calculation unit 37 corresponding to the centrifugal pressure calculation means calculates the centrifugal pressure P ₁ to the secondary pulley 2 on which the line pressure P _L acts as P ₁ = K · N _sec ² (however,
K is a constant), and the compensator 38 uses the value P ₀ -P ₁ obtained by subtracting the centrifugal pressure P ₁ from the required line pressure P ₀ described above as the target line pressure, and the allowable maximum line pressure as illustrated in FIG. The target line pressure P _L that does not exceed the allowable maximum line pressure is determined by passing the limit line 39 to the set limiter 39.

The line pressure solenoid duty determining section 40 corresponding to the no-load line pressure adjusting means determines the duty D corresponding to the above-mentioned target line pressure P _L based on the map shown in FIG. 8, for example. Line pressure solenoid 1
Output to 4. Here, the solenoid 14 applies a constant pressure P _C from the pilot valve 15 to the modifier valve 13 as a duty pressure P _D according to the driving duty _D , and the modifier valve 13 applies the modifier pressure P D according to the duty D. _m is applied to the pressure regulator valve 12, and the pressure regulator valve 12 regulates the hydraulic oil from the pressure source 11 to the line pressure P _L according to the duty D. As described above, the line pressure is controlled to the target line pressure P _L set as described above.

By the way in this embodiment, the engine torque T _e, as shown in FIG. 5 a <br/> reverse torque at all engine speed range, even when the engine no-load and the throttle opening TVO to 0/8 , one by one accurately determined according ene <br/> Jin speed N _e is greater as the absolute value increases engine torque T _e of the engine speed N _e in all engine speed range, from which total engine speed range negative transmission input torque T _i in which the absolute value the larger the engine <br/> down speed N _e is increased by accurately estimated in, in accordance with the speed change transmission input torque T _i as shown in FIG. 6, Since the line pressure control is performed so that the target line pressure P _L does not have excess or deficiency for each gear ratio i, the above-mentioned problem that has occurred in the conventional device,
In other words, since the line pressure had to be set higher than necessary during no-load operation, the engine brake was too effective to give the driver a feeling of strangeness, and the operating oil temperature of the continuously variable transmission was overheated. It is possible to solve various problems such as deterioration of belt durability at once.

Further, with the rotation of the secondary pulley 2 on which the line pressure P _L is to be applied, the centrifugal pressure P ₁ applied thereto is added.
By determining a target line pressure P _L by subtracting the can working pressure of the secondary pulley 2 due to the centrifugal pressure P ₁ is prevented from becoming excessive, action of the above embodiment in the centrifugal pressure P ₁ It is possible to avoid the effects being offset.

[0030]

As described above, the line pressure control device for a V-belt type continuously variable transmission according to the first aspect of the present invention, as set forth in claim 1, has a rotational speed of the prime mover in a no-load state of the prime mover before the continuously variable transmission. Based on the above , the negative torque of the prime mover is calculated such that the absolute value increases as the prime mover speed increases over the entire range of the prime mover speed.
The absolute value of the transmission becomes larger as the prime mover speed increases over the entire range.The negative input torque of the transmission is calculated, and the line pressure is set to a value corresponding to the negative input torque when the prime mover is not loaded. because was configured for pressurizing regulated according to the negative torque of the prime mover by pressure regulating, no load and雖even line pressure, will be controlled to an appropriate value corresponding to the torque to be negative in the entire region of the engine rotational speed , The above-mentioned problem that has often occurred in the past due to the fact that the line pressure in an unloaded state is often too high, that is, the engine braking is too effective and makes the driver feel uncomfortable, or operates the continuously variable transmission. It is possible to avoid the problem that the oil temperature becomes overheated and the durability of the V-belt is lowered.

Further, in the first aspect of the present invention, when the negative torque of the prime mover which is the source of the input torque under no load is obtained, based on the detected number of revolutions of the prime mover, the whole range of the prime mover revolution speed is obtained. Since the negative value of the prime mover, whose absolute value increases as the detected prime mover speed increases, the negative torque becomes closer to the actual value in consideration of the prime mover speed. The input torque under no load becomes accurate, and the above-described effect of preventing the line pressure from becoming too high under no load can be further ensured.

A line pressure control device for a V-belt type continuously variable transmission according to a second aspect of the present invention, as described in claim 2 , calculates the currently selected gear ratio of the continuously variable transmission and calculates the line pressure when there is no load. At the time of control, not only the input torque at no load but also the line pressure at no load is controlled according to the calculated gear ratio, so that the line pressure at no load is a proper value with no excess or deficiency. can be controlled, it is possible to the effects of the first invention further secure ones.

[0033] The third invention the line pressure control device of the V-belt type continuously variable transmission according to the as described in claim 3, calculates the centrifugal pressure acting on the movable flange side of the pulley that over the line pressure, Since the line pressure is reduced by the calculated centrifugal pressure when the line pressure is controlled under no load, it is possible to eliminate the influence of the centrifugal pressure and bring the line pressure closer to the required value. or the effect of the second invention can be made more prominent.

[Brief description of drawings]

FIG. 1 is a hydraulic control system diagram illustrating a line pressure control device for a V-belt type continuously variable transmission according to the present invention together with a shift control device.

FIG. 2 is a diagram showing a normal shift control pattern used for shift control in the same example.

FIG. 3 is a functional block diagram relating to a line pressure control unit of the controller in the example.

FIG. 4 is a performance diagram showing a relationship between a speed ratio and a torque ratio of the torque converter.

FIG. 5 is an engine performance diagram used to determine engine torque.

FIG. 6 is a diagram showing required line pressure characteristics defined by a transmission input torque and a gear ratio.

FIG. 7 is a characteristic diagram showing a limit value of an allowable maximum line pressure.

FIG. 8 is a relationship diagram of a line pressure solenoid duty with respect to a target line pressure.

[Explanation of symbols]

1 Primary Pulley 1b Movable Flange 2 Secondary Pulley 2b Movable Flange 3 V Belt 11 Pressure Source 12 Pressure Regulator Valve 13 Pressure Modifier Valve 14 Line Pressure Solenoid 15 Pilot Valve 17 Controller 18 Throttle Opening Sensor (No Load Condition Detection Means) 19 Primary Pulley rotation sensor 20 Secondary pulley rotation sensor 21 Shift control valve 22 Shift link 23 Step motor 24 Shifter 25 Line pressure circuit 26 Shift control pressure circuit 27 Engine rotation sensor (motor rotation speed detection means) 31 Speed ratio calculation unit 32 Torque ratio calculation unit 33 Engine Torque Estimating Unit 34 Input Torque Estimating Unit (No-Load Input Torque Calculating Means) 35 Gear Ratio Calculating Means (Gear Ratio Calculating Means) 36 Required Line Pressure Calculating Means 37 Centrifugal Pressure Calculating Means (Centrifugal Pressure Calculating Means) 38 Compensator 39 Limiter 40 Line pressure solenoid duty determination unit (when no load is applied) In pressure adjustment means)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI F16H 59:42 F16H 59:42 59:70 59:70 101: 02 101: 02 (56) Reference JP-A-2-221758 ( JP, A) JP-A 2-190665 (JP, A) JP-A 2-62464 (JP, A) JP-A 62-106164 (JP, A) JP-A 5-296331 (JP, A) JP JP 5-280625 (JP, A) JP 4-8961 (JP, A) JP 63-270971 (JP, A) JP 64-18735 (JP, A) JP 1-206155 (JP , A) J. Kohei 5-22682 (JP, Y2) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40 -63/48

Claims (3)

(57) [Claims] 1. A line pressure is applied to a movable flange of one of a pair of pulleys around which a V belt is wound, and a line pressure is reduced to a movable flange of the other pulley by a shift control valve. In the V-belt type continuously variable transmission in which the transmission control pressure is applied and the transmission ratio is controlled steplessly by the pressure difference between the transmission control pressure and the line pressure, the load of the prime mover in front of the continuously variable transmission is No-load state detection means for detecting that the state is a no-load state, a prime mover rotation speed detection means for detecting the number of rotations of the prime mover, during detection of the no-load state by the no-load state detection means, the Based on the number of revolutions of the prime mover, the prime mover rotation
It calculates the negative torque of prime mover absolute value larger the engine rotational speed and the detected across several increases from the torque, the larger the engine rotational speed across the prime mover rotational speed absolute value becomes larger shift A no-load input torque calculation means for obtaining a negative no-load input torque of the machine; and by adjusting the line pressure to a value corresponding to the negative no-load input torque during detection of the no-load state. A line pressure control device for a V-belt type continuously variable transmission, comprising: a no-load line pressure adjusting means for adjusting the pressure according to the negative torque of the prime mover. To 2. A method according to claim 1 Oite, continuously variable transmission adds the speed ratio calculation means for calculating a speed ratio of the currently selected, the no-load line pressure adjusting means only the no-load input torque In addition, the line pressure control device for a V-belt type continuously variable transmission is characterized in that the line pressure is adjusted during detection of the no-load state according to the calculated gear ratio. 3. The centrifugal pressure calculation means for calculating the centrifugal pressure acting on the movable flange of one of the pulleys according to claim 1 or 2 , wherein the no-load line pressure adjustment means is the calculated centrifugal pressure. A line pressure control device for a V-belt type continuously variable transmission, which is configured to reduce the line pressure only.