JPH09229186A - Speed change control device of continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an excessive rise of the oil temperature, as well as to recognize the trouble of a lockup mechanism rapidly, by providing a correcting means to change the minimum value of the change gear ratio to the low side, when the slip of a torque converter is decided, in the fastening condition of the lockup mechanism. SOLUTION: The change gear ratio of a continuously variable transmission 100 is controlled continuously according to the operating condition of a vehicle, and a lockup mechanism 103 between an engine is fastened selectively. When a slip of a torque converter 102 is generated in the fastening condition of the lockup mechanism 103, the minimum value of the change gear ratio is changed to the low side by a correcting means 105. As a result, when the vehicle is traveling at the highest speed setting at the highest position, for example, the change gear ratio is converted to the low side, the difference of the rotation frequencies at the input shaft and the output shaft of the converter 102 is reduced, the heating from the converter 102 is reduced to prevent the rise of the oil temperature, and at the same time, a trouble of the converter 102 can be recognized from the rise of the engine speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a shift control device for a continuously variable transmission equipped with a torque converter having a lockup mechanism, and more particularly to a failsafe of the lockup mechanism.

[0002]

2. Description of the Related Art A continuously variable transmission mounted on a vehicle has conventionally been known to include a torque converter as a starting element.
-105347 publication and the like.

In this system, a torque converter provided with a lock-up mechanism is interposed between a continuously variable transmission and an engine, and at the time of starting, driving torque is transmitted to the continuously variable transmission by fluid transmission of the torque converter, while traveling. Among them, the lock-up clutch is engaged to continuously change the gear ratio to achieve both economical efficiency and drivability. Furthermore, since the torque converter only needs to have a capacity as a starting element, it is continuously variable. It is possible to reduce the size and weight of the transmission.

Further, as a means for preventing the oil temperature of the torque converter from rising excessively, Japanese Patent Laid-Open No. 62-74726 and the like are known. When the oil temperature of the automatic transmission exceeds a predetermined value, a downshift occurs. The point is moving to the high speed side.

[0005]

However, in the former conventional example described above, the torque converter arranged as the starting element is locked up at all times during traveling, so that the capacity thereof is set small so that the size and weight can be reduced. Can be promoted, but when the capacity of the torque converter is set as the starting element,
If the lockup mechanism fails in a heavy load area such as during high-speed traveling, the slip of the torque converter increases, and the oil temperature of the torque converter and the continuously variable transmission rises to high temperature, which increases the durability of the continuously variable transmission. There is a problem that it is difficult for the driver to easily recognize the abnormality of the torque converter because the downshift point is only moved to the high speed side in the latter conventional example. there were.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to allow a driver to quickly and easily recognize a failure of a lockup mechanism and prevent an excessive increase in oil temperature. .

[0007]

A first invention, as shown in FIG. 6, is a gear shift control means 101 for continuously controlling a gear ratio of a continuously variable transmission 100 according to a driving state of a vehicle, and a vehicle. Of the continuously variable transmission having a lockup mechanism 103 that is selectively engaged according to the operating state of the vehicle and a torque converter 102 interposed between the engine and the continuously variable transmission 100. In the lockup mechanism 10
Lockup failure determination means 104 for determining slip of the torque converter 102 when 3 is in the engaged state, and correction for changing the minimum value of the gear ratio to a predetermined Low side when slip of the torque converter 102 is determined. And means 105.

In a second aspect based on the first aspect, the torque converter is interposed as a starting element, and the lockup mechanism is fastened at a predetermined vehicle speed or higher.

In a third aspect based on the first aspect, the lockup failure determination means locks when the difference between the input shaft rotation speed and the output shaft rotation speed of the torque converter becomes a predetermined value or more. Determine the failure of the up mechanism.

[0010]

Therefore, in the first aspect of the present invention, the gear ratio of the continuously variable transmission is continuously controlled according to the operating condition of the vehicle, and the lockup mechanism interposed between the engine and the engine is also in the operating condition of the vehicle. However, if the torque converter slips while the lock-up mechanism is in the engaged state, the correction unit changes the minimum value of the gear ratio to the Low side, so that the gear ratio is the highest. When the vehicle is traveling at high speed in the position, the gear ratio is shifted to the Low side, and the difference in the number of revolutions of the input shaft and the output shaft of the torque converter is reduced
The heat generation from the torque converter can be reduced to prevent the oil temperature from rising, and at the same time, the engine speed increases, so that the driver can be made aware of the failure of the torque converter.

In the second aspect of the invention, the torque converter is used as the starting element to engage the lockup mechanism at a predetermined vehicle speed or higher, so that the capacity of the torque converter is reduced to reduce the size and weight of the continuously variable transmission. be able to.

Further, according to the third aspect of the present invention, since the failure of the lockup mechanism is determined when the difference between the input shaft rotation speed and the output shaft rotation speed of the torque converter becomes a predetermined value or more, a small amount of the lockup mechanism is detected. It is possible to prevent erroneous determination due to slip.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic block diagram of a shift control device for a V-belt type continuously variable transmission, and FIG. 2 is a vertical sectional view of a continuously variable transmission 17 equipped with a torque converter having a lockup mechanism.

A torque converter 12 as a starting element is interposed between an engine (not shown) and the continuously variable transmission 17, and the continuously variable transmission 17 is connected to the output side of the torque converter 12 as a variable pulley. Primary pulley 16
And a secondary pulley 26 connected to the drive shaft,
These variable pulleys are connected by a V belt 24.

Torque converter 1 as the starting element
2 is provided with a lockup clutch 11 that connects the input side and the output side, and a predetermined operating state, for example, a vehicle speed VSP
Is greater than or equal to the predetermined value Va, the lockup clutch 11
Are concluded.

The gear ratio of the continuously variable transmission 17 and the lockup clutch 11 are the same as those of the CVT control unit 1.
It is controlled by the hydraulic control valve 3 which responds to the command from.

The CVT control unit 1 includes a primary pulley rotation speed sensor 6 for detecting the rotation speed Npri of the primary pulley 16 of the continuously variable transmission 17 and a secondary pulley rotation speed sensor 7 for detecting the rotation speed Nsec of the secondary pulley 26. Signal and inhibitor switch 8
And the throttle opening TVO (or accelerator pedal opening) from the throttle opening sensor 5 in accordance with the selected position of the accelerator pedal operated by the driver and the fuel injection amount of an engine (not shown) or Engine control unit 2 for controlling ignition timing etc.
The engine speed Ne is read from to control the variable control of the gear ratio of the continuously variable transmission 17 and the engagement state of the lockup clutch 11 of the torque converter 12 in accordance with the operating state of the vehicle or the driver's request. . In the present embodiment, the vehicle speed VSP is obtained by multiplying the secondary rotation speed Nsec by a predetermined conversion constant, and the vehicle speed VSP is the predetermined value Va.
Thus, the lockup clutch 11 is engaged.

A V-belt type continuously variable transmission 17 having a torque converter 12 as a starting element will be described with reference to FIG.

A torque converter 12 as a hydraulic power transmission device is connected between an engine output shaft 10 connected to an engine (not shown) and an input shaft 13 of a continuously variable transmission 17, and the torque converter 12 is shown in FIG. CVT control unit 1 via hydraulic control valve 3
The lock-up clutch 11 is controlled according to the lock-up signal LU from.

The engine output shaft 10 is a pump impeller 12
a, the input shaft 13 of the continuously variable transmission 17 is the turbine runner 1
The lock-up clutch 11 is selectively coupled between the pump impeller 12a and the turbine runner 12b according to the hydraulic pressure from the hydraulic pressure control valve 3 respectively.

The input shaft 13 of the continuously variable transmission 17 is connected to a forward / reverse switching mechanism 15 mainly composed of a planetary gear mechanism 19, and the continuously variable transmission 1 is connected to a drive shaft 14 of the planetary gear mechanism 19.
A primary pulley 16 on the drive side of 7 is provided.

The primary pulley 16 includes a fixed conical plate 18 which rotates integrally with the drive shaft 14, and a fixed conical plate 18.
And a movable conical plate 22 that is disposed so as to face each other to form a V-shaped pulley groove and is displaceable in the axial direction of the drive shaft 14 by the hydraulic pressure acting on the primary pulley cylinder chamber 20 (primary pulley hydraulic pressure). The primary pulley cylinder chamber 20 is composed of oil chambers 20a and 20b and has a larger pressure receiving area than a secondary pulley cylinder chamber 32 described later.

On the other hand, the secondary pulley 26 has a driven shaft 28.
And a fixed conical plate 30 that rotates integrally with the driven shaft 28, and a V-shaped pulley groove that is disposed so as to face the fixed conical plate 30 and that moves to the secondary pulley cylinder chamber 32. The movable conical plate 34 is configured to be displaceable in the axial direction of the driven shaft 28 according to the acting hydraulic pressure (secondary hydraulic pressure).

A drive gear 46 that meshes with an idler gear 48 is fixed to the driven shaft 28, and a pinion gear 54 provided on an idler shaft 52 of the idler gear 48 is a final gear 4.
4 is engaged. The final gear 44 is a differential device 5.
A drive shaft or a propeller shaft (not shown) is driven via 6.

The drive torque input from the engine output shaft 10 is applied to the torque converter 12 and the forward / reverse switching mechanism 15.
Is transmitted to the input shaft 1 via the planetary gear mechanism 19 that is in an integrally rotating state when the forward clutch 40 is engaged and the reverse brake 50 is released.
It is transmitted to the drive shaft 14 in the same rotation direction as that of No. 3. On the other hand, when the forward clutch 40 is released and the reverse brake 50 is engaged, the drive torque transmitted to the input shaft 13 by the action of the planetary gear mechanism 19 is in a state where the rotation direction is reversed. It is transmitted to the drive shaft 14.

The drive torque of the drive shaft 14 is transmitted from the drive gear 46 to the idler gear 4 via the primary pulley 16, the V belt 24, the secondary pulley 26, and the driven shaft 28.
8, the idler shaft 52, the pinion gear 54, and the final gear 44.

In transmitting the driving force as described above, the movable conical plate 22 of the primary pulley 16 and the secondary pulley 2
6 by displacing the movable conical plate 34 of 6 in the axial direction,
By changing the contact radius with 4, the rotation ratio of the primary pulley 1 and the secondary pulley 26, that is, the gear ratio can be changed.

For example, if the width of the V-shaped pulley groove of the primary pulley 16 is reduced, the V on the secondary pulley 26 side is reduced.
Since the contact radius of the belt 24 is large, a large gear ratio can be obtained. If the movable conical plates 22 and 34 are displaced in the opposite direction, the gear ratio becomes smaller.

The control for changing the width of the V-shaped pulley groove of the primary pulley 16 and the secondary pulley 26 is performed by the hydraulic control of the primary pulley cylinder chamber 20 and the secondary pulley cylinder chamber 32.

The above gear ratio control is performed by controlling the line pressure solenoid 4 of the hydraulic control valve 3,
The line pressure solenoid 4 is the CVT control unit 1
It is driven by duty control or the like.

Next, an example of the shift control performed by the CVT control unit 1 will be described in detail with reference to the flow chart of FIG. 3 and the control conceptual diagram of FIG. The flowchart of FIG. 3 is assumed to be performed every predetermined time.

In step S1, the primary rotation speed Npri, the vehicle speed VSP (= secondary rotation speed Nsec), and the throttle opening TVO according to the driver's operation are read from the continuously variable transmission 17 and the engine control unit 2 is read. The engine speed Ne is read.

In step S2, a target value of the primary speed Npri is calculated from the vehicle speed VSP and the throttle opening TVO based on the speed change map shown in FIG. RT
O is calculated. This calculation process is performed by the target primary rotation speed calculation unit and the target gear ratio calculation unit shown in FIG. The shift map of FIG. 5 uses the throttle opening TVO as a parameter to set the primary rotation speed Npri according to the vehicle speed VSP.
The target value of is set in advance.

Then, in step S3, the current vehicle speed V
It is determined whether SP is equal to or higher than a predetermined lockup speed Va. If the SP is equal to or higher than the lockup vehicle speed Va, the process proceeds to step S4. If not, the process proceeds to the gear ratio output process of step S7.

A step S4 compares the read primary rotation speed Npri with the reading error B with the engine rotation speed Ne to determine whether the torque converter 12 is slipping or not. If so, the routine proceeds to step S5, where it is determined that a failure has occurred in the lockup clutch 11, while if not so, the processing proceeds to the gear ratio output processing at step S7 (fault determination unit in FIG. 4).

When it is determined that the lockup clutch 11 is out of order, the target speed ratio RTO is limited in step S6.

This is as shown in the shift map of FIG.
The maximum High gear ratio of the target gear ratio RTO (minimum value of the gear ratio to be set) is restricted, and the lockup clutch 1
When 1 is normal, it is set to the highest High gear ratio as indicated by the broken line in the figure, but if a failure of the lockup clutch 11 is determined, the highest High line is changed to the Low side in the figure, and the highest High speed at this time is set. The gear ratio is set to a predetermined value larger than 1.0.

Thus, when the lockup clutch 11 is out of order, the maximum High gear ratio is set to a predetermined Lo.
By changing to the w side, the target gear ratio RTO obtained in step S2 is corrected, and based on the corrected gear ratio RTO, in step S7, the hydraulic control valve 3 is driven to drive the primary pulley 16 and the secondary pulley. Pulley 26
The belt contact radius is changed to match the actual gear ratio with the target gear ratio. The hydraulic control according to the gear ratio RTO is disclosed in Japanese Patent Application No. 7-11 proposed by the applicant of the present application.
The line pressure solenoid 4 uses the hydraulic pressure supplied from the oil pump to generate a pressure control valve (not shown) and a constant pressure valve (not shown) that constitute the hydraulic control valve 3. It is to adjust to the required line pressure via.

When it is determined that the lockup clutch 11 has failed during traveling by the above control, the maximum H
Since the gear ratio on the high side is changed to the Low side, the primary rotational speed Npri increases and the rotational speed difference from the engine rotational speed Ne decreases, so heat generation due to slip of the torque converter 12 is suppressed, and the oil temperature is reduced. Of the continuously variable transmission 17 and the torque converter 12 can be ensured. Therefore, the torque converter 12 only needs to have a capacity according to the start of the vehicle. It is possible to promote the reduction in size and weight of the continuously variable transmission including the torque converter 12.

Further, the driver is required to operate the lockup clutch 1
At the time of failure of No. 1, since the primary rotation speed Npri increases as compared with the normal time, the engine rotation speed Ne also rises, so that it is possible to easily recognize that the abnormality has occurred in the torque converter 12. Since the failure determination of the lockup clutch 11 is made when the difference between the rotational speeds of the input and output shafts of the torque converter 12, that is, the difference between the engine rotational speed Ne and the primary rotational speed Npri is equal to or greater than a predetermined value B, the failure determination is performed. Due to a slight slip of the lockup clutch 11, the gear ratio is frequently set to Low.
It is possible to prevent drivability to the side and secure drivability.

In the above embodiment, an example in which the continuously variable transmission 17 is constituted by a V-belt type is shown, but it is not shown, but the same can be said if it is constituted by a toroidal type or the like.

[0043]

As described above, according to the first aspect of the invention, the gear ratio of the continuously variable transmission is continuously controlled according to the operating state of the vehicle, and the lockup mechanism interposed between the engine and the engine is also provided. It is selectively engaged according to the operating state of the vehicle. However, if the torque converter slips while the lock-up mechanism is in the engaged state, the correction unit changes the minimum value of the gear ratio to the Low side. If the gear ratio is in the highest position, such as during high-speed traveling, the gear ratio is shifted to the Low side, the difference between the rotational speeds of the input shaft and the output shaft of the torque converter is reduced, and heat generation from the torque converter is reduced. The oil temperature can be prevented from rising and the durability of a continuously variable transmission equipped with a torque converter can be improved. At the same time, the engine speed increases, so the driver can easily recognize the failure of the torque converter. It can be.

In the second aspect of the invention, the torque converter is used as the starting element and the lockup mechanism is engaged at a predetermined vehicle speed or higher. Therefore, the capacity of the torque converter is reduced to reduce the size and weight of the continuously variable transmission. be able to.

According to the third aspect of the invention, since the failure of the lockup mechanism is determined when the difference between the input shaft rotation speed and the output shaft rotation speed of the torque converter becomes a predetermined value or more, a small amount of the lockup mechanism is detected. It is possible to prevent erroneous determination due to slip and ensure drivability.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view of the continuously variable transmission.

FIG. 3 is a flowchart showing an example of control performed by a CVT control unit, showing a main routine.

FIG. 4 is a conceptual diagram of control similarly.

FIG. 5 is a shift map showing the relationship between the vehicle speed VSP and the target primary rotation speed Npri using the throttle opening TVO as a parameter.

FIG. 6 is a claim correspondence diagram corresponding to any one of the first to third inventions.

[Explanation of symbols]

 1 CVT Control Unit 2 Engine Control Unit 3 Hydraulic Control Valve 4 Line Pressure Solenoid 5 Throttle Opening Sensor 6 Primary Speed Sensor 7 Secondary Speed Sensor 10 Engine Output Shaft 11 Lockup Clutch 12 Torque Converter 13 Input Shaft 14 Drive Shaft 15 Around 15 Progressive switching mechanism 16 Primary pulley 17 Continuously variable transmission 18 Fixed conical plate 19 Planetary gear mechanism 20 Primary pulley cylinder chamber 22 Movable conical plate 24 V-belt 26 Secondary pulley 28 Driven shaft 30 Fixed conical plate 32 Secondary pulley cylinder chamber 34 Movable conical plate 40 Forward clutch 44 Final gear 46 Drive gear 48 Idler gear 50 Reverse brake 52 Idler shaft 54 Pinion gear 56 Differential device 100 Continuously variable transmission 01 the shift control means 102 torque converter 103 lockup mechanism 104 failure determining means 105 compensation means

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Claims (3)

[Claims] 1. A shift control means for continuously controlling a gear ratio of a continuously variable transmission according to a driving state of a vehicle, and a lock-up mechanism selectively engaged according to a driving state of the vehicle. A shift control device for a continuously variable transmission, comprising: a torque converter interposed between an engine and the continuously variable transmission; and a lockup for determining a slip of the torque converter when the lockup mechanism is in an engaged state. A shift control device for a continuously variable transmission, comprising: failure determination means; and correction means for changing the minimum value of the gear ratio to a predetermined Low side when a slip of the torque converter is determined. 2. The shift control device for a continuously variable transmission according to claim 1, wherein the torque converter is interposed as a starting element, and the lockup mechanism is engaged at a predetermined vehicle speed or higher. 3. The lockup failure determination means determines a failure of the lockup mechanism when the difference between the input shaft rotation speed and the output shaft rotation speed of the torque converter exceeds a predetermined value. Item 2. A shift control device for a continuously variable transmission according to Item 1.