JPH08178050A - Speed change control device for v-belt type continuously variable transmission - Google Patents

Abstract

PURPOSE: To teach the abnormality of a line pressure control system to a driver via speed change control. CONSTITUTION: A controller 17 obtains the target input revolving speed Nis from the input information and operates a valve 21 with a step motor 23 via a link 22 in response to it. The valve 21 regulates the control pressure Ps and continuously changes the transmission ratio between pulleys 1, 2 to the ratio corresponding to the target input revolving speed Nis . At the time of an abnormality when the original line pressure PL of the control pressure Ps is increased, a relief valve 27 excludes the Control pressure Ps at this time and reduces it to a value equivalent to the relief valve opening pressure. A speed change to change gear ratios other than the lowest change gear ratio cannot be made, and the line pressure abnormality can be reported to a driver. At the time of an abnormality when the line pressure PL is decreased, the controller 17 forcibly makes a down-shift speed change, and this abnormality is reported to the driver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed change control device for a V-belt type continuously variable transmission, and more particularly, to a speed change control device capable of sensuously instructing a driver when the line pressure control system fails. Involved in

[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, as shown in FIG. 4, the line pressure P _L is
When producing by reducing the pump pressure P _p , it is necessary to control to a marginal value according to the input torque (represented by the engine throttle opening TVO) between the maximum value P _Lmax and the minimum value P _{Lmin for} each gear ratio _. It is a common practice. Therefore, even if the line pressure P _L is high or low from such a controlled value, the V-belt durability is adversely affected.

[0005]

However, in the conventional shift control device for a V-belt type continuously variable transmission, which is represented by the above-mentioned document, when the line pressure control system fails. Was not considered, and it was confirmed that the following problems would occur. That is, as shown in FIG. 5 (a), when the line pressure control valve is in the closed state and the line pressure P _L remains at a high constant value which is the same as the pump pressure P _p , a failure is also shown in FIG. 5 (b). As described above, even when there is a failure in which the line pressure P _L remains at a high constant value (maximum value within the pressure adjustment range) due to an abnormality in the line pressure solenoid that creates the line pressure control signal pressure to the line pressure control valve, control valve is the line pressure P _L
Therefore, the shift control pressure P _S required to achieve each gear ratio can be created, so that the driver can continue driving forever without knowing these abnormalities.

[0006] When the abnormal line pressure P _L of such line pressure control system is left high constant value, without should the line pressure P _L is a suitable value as described above per FIG 4, V belt The durability of the machine is significantly reduced, and the transmission efficiency is significantly reduced. Such inconvenience is caused by the line pressure P
Assuming a failure where _L becomes a high constant value, line pressure P _L
Even if a relief valve for eliminating the excessive amount of is provided, the line pressure P _L is only maintained at a constant value corresponding to the opening pressure of the relief valve, and therefore, nothing is solved.

According to the present invention, even when any of the above line pressure control systems fails, the V-belt type continuously variable transmission is unnaturally shifted, and the driver is quickly informed of the failure. Therefore, it is an object of the present invention to propose a shift control device for a V-belt type continuously variable transmission that can prompt repair of the failure.

[0008]

To this end, the gear shift control device according to the first aspect of the present invention applies a line pressure to the movable flange of one of a pair of pulleys around which a V-belt is wound, and the other pulley. A V-belt in which a shift control pressure obtained by reducing the line pressure by a shift control valve is applied to the movable flange, and the speed ratio is controlled steplessly by the differential pressure between the shift control pressure and the line pressure. In a continuously variable transmission, a pipe line that guides the shift control pressure to the other pulley,
The valve opening pressure is higher than the maximum value of the shift control pressure while the line pressure is normal, but the line pressure remains at the same upper limit value as the pressure of the pressure source. Unchangeable gear ratio when the line pressure control system fails. It is characterized in that a relief valve having a valve opening pressure for causing the above is connected.

Further, in the shift control device for the V-belt type continuously variable transmission according to the second aspect of the present invention, the line pressure control in which the opening pressure of the relief valve remains at the same upper limit value as the line pressure is the pressure of the pressure source. It is characterized in that the valve opening pressure is lower than the shift control pressure at the time of system failure.

Further, in the shift control device for the V-belt type continuously variable transmission according to the third aspect of the invention, the maximum speed ratio command detecting means for detecting that the selection command for the maximum speed ratio is issued and the actual speed ratio are detected. Detecting the gear ratio detecting means, and detecting that the actual gear ratio is not the highest gear ratio even though the command for selecting the highest gear ratio is issued in response to the signals from these means. A gear ratio abnormality detecting means and a forced downshift gear changing means for forcibly bringing the gear ratio to a low speed side when the gear ratio is abnormal in response to a signal from the means are added. is there.

In the shift control device for a V-belt type continuously variable transmission according to the fourth aspect of the present invention, the forced downshift transmission means is
In the event of a line pressure control system failure in which the line pressure remains at the upper limit of the hardware limit, the gear ratio that can be achieved by the presence of the relief valve is forced to a gear ratio lower than the highest gear ratio. It is characterized in that it is configured to perform a downshift shift.

[0012]

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, the line pressure is applied to the movable flange of one of the pair of pulleys, 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. As a result, the V-belt type continuously variable transmission can continuously achieve a speed ratio corresponding to the differential pressure between the shift control pressure and the line pressure. Therefore, an arbitrary gear ratio can be obtained by determining the gear shift control pressure by the above gear shift control valve.

Here, the relief valve connected to the conduit for guiding the shift control pressure to the other pulley has a valve opening pressure higher than the maximum value of the shift control pressure while the line pressure is normal. Therefore, it does not hinder the shift control.

By the way, when the line pressure control system fails in which the line pressure remains the same upper limit value as the pressure of the pressure source, the valve opening pressure of the relief valve cannot be achieved by the continuously variable transmission at least on the high speed side. Produce a gear ratio range. Therefore, the driver can know the abnormal line pressure when he / she senses that the high speed side gear ratio should not be selected at least when the driver is in a traveling state, and is aware of this failure. It is possible to eliminate the problem that the durability of the V-belt is significantly reduced after traveling for a long period of time.

In the shift control device for the V-belt type continuously variable transmission according to the second aspect of the invention, the line pressure control system in which the valve opening pressure of the relief valve remains the same upper limit value as the pressure of the pressure source. Since the valve opening pressure is lower than the shift control pressure at the time of the failure, the continuously variable transmission becomes completely out of control at the time of the failure, and the driver is kept at the lowest speed ratio. You can know this at the same time as the failure.

When the line pressure remains at the upper limit of the hardware limit and the line pressure control system fails, the relief valves according to the first and second aspects of the invention provide the maximum speed ratio of the continuously variable transmission. Disable gear shifting. However, since it is difficult for the driver to know the failure if the gear shifting is impossible in such a high speed gear ratio range, in the third aspect of the invention, it is most preferable that the command for selecting the highest speed gear ratio is issued. Despite being detected by the high speed gear ratio command detection means,
While the actual gear ratio detected by the gear ratio detecting means is not the highest gear ratio, the forced downshift gear means forcibly reduces the gear ratio of the continuously variable transmission to the low gear ratio while the gear ratio abnormality detecting means detects it. Make the downshift shift brought to the side. Thus, due to this unnatural forced downshift, the driver can sense the abnormality of the line pressure sensibly, and the vehicle runs for a long time without being aware of this failure, and the durability of the V-belt is significantly reduced. The problem of causing it can be eliminated.

In the shift control device for a V-belt type continuously variable transmission according to the fourth aspect of the present invention, the forced downshift transmission means is used when the line pressure remains at the upper limit of the hardware limit when the line pressure control system fails. In the above, the continuously variable transmission is forcibly downshifted to a gear ratio lower than the highest gear ratio that can be achieved by the presence of the relief valve. In this case, it is possible to more reliably teach the driver of the abnormal line pressure due to the forced downshift, and the above-described operational effect can be further ensured.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 illustrates a shift control device for a V-belt type continuously variable transmission according to the present invention, where 1 is a primary pulley as an input pulley to which engine rotation is input, and 2 is an output pulley that outputs rotation after shifting. The secondary pulleys are shown respectively. The V-belt 3 is wound around the primary pulley 1 and the secondary pulley 2,
It is possible to continuously change the transmission ratio between pulleys, that is, the gear ratio by changing the winding arc diameter of the V-belt 3 with respect to.

Therefore, in the primary pulley 1, the movable flange 1b forming the pulley V groove facing the fixed flange 1a is displaceable 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 now be described. This line pressure control system is a pressure source 11.
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.

Since the controller 17 also controls the shift, the controller 17 has a signal from the vehicle speed sensor 18 for detecting the vehicle speed VSP and a signal from the throttle opening sensor 19 for detecting the engine throttle opening TVO. And a signal from an input rotation sensor 20 for detecting the transmission input rotation speed (which may be the engine rotation speed) N _i .

Next, the shift control system will be described. This shift control system comprises a shift control valve 21 for determining the shift control pressure P _S , a shift link 22, and a step motor 23. The speed change link 22 has one end connected to a shifter 24 which is displaced together with the primary pulley movable flange 1b, the other end connected to be rotated by a step motor 23, and the both ends are pivotally attached to a spool 21a of the speed change control valve 21. To do. 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 gear change control, the controller 17
Is based on a map corresponding to the shift control characteristic shown in FIG. 3, for example, the target input rotation speed N _iS is obtained from the vehicle speed VSP and the throttle opening TVO, and a shift command corresponding to this is issued to the step motor 23. . 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
Changes the gear shift control pressure P _S, and the movable flanges 1b and 2b of the pulleys 1 and 2 are displaced, so that the gear ratio is brought to the gear ratio corresponding to the target input speed N _iS .

As the shift proceeds, the movable flange 1b of the primary pulley 1 rotates the shift link 22 around the step motor 23 through the shifter 24 so as to return the shift control valve spool 21a to the original stroke position.
When the gear ratio reaches the gear ratio corresponding to the target input speed N _iS , the gear shift control ends, and this gear ratio can be maintained.

In controlling the line pressure P _L , the controller 17 uses the map corresponding to the line pressure control characteristics shown in FIG. 4, for example, as the target line pressure P from the above gear ratio and throttle opening TVO. _L is calculated, and the drive duty D corresponding to this is determined by the line pressure solenoid 14
Command. Here, the solenoid 14 is the pilot valve 1
The constant pressure P _C from 5 is applied to the modifier valve 13 as the duty pressure P _D according to the drive duty D, and the modifier valve 13 applies the modifier pressure P _m according to the duty D to the pressure regulator valve 12. Then
The pressure regulator valve 12 regulates the hydraulic oil from the pressure source 11 to a line pressure P _L according to the duty D. As described above, the line pressure P _L is controlled according to the line pressure control characteristic shown in FIG.

By the way, in this example, the pressure regulator valve (line pressure control valve) 12 of the above line pressure control system fails, and the line pressure P _L is changed to the pump pressure P _p as shown in FIG. 5 (a). A relief valve 27 is additionally provided in order to inform the driver of this abnormally when the value remains as high as the above value. If the relief valve 27 is not provided, despite the abnormality, an arbitrary gear ratio can be obtained by adjusting the gear shift control pressure P _S as shown in FIG. Until then, the continuously variable transmission will be used with this abnormal line pressure P _L. In this case, the tension of the V-belt 3 becomes excessive as described above, and the durability thereof is significantly reduced. Then
As shown by the broken line in FIG. 5A, the valve opening pressure of the relief valve 27 is set to be lower than the required gear shift control pressure P _S at the time of the failure, so that the gear shift control pressure of the circuit 26 becomes equal to the required pressure. will be a value less than P _S, remains held eventually become shifting impossible slowest speed ratio, which with a said abnormal sensuously teaches the driver to prompt the repair of the fault be able to.

Note that the valve opening pressure of the relief valve 27 is not limited to that shown by the broken line in FIG. 5 (a) as long as it can generate an unshiftable range so as to achieve the above object. It shall be not even be such as to intersect the required shift control pressure (P _S) line no problem. However, in any case, the valve opening pressure of the relief valve 27 is higher than the maximum value of the required shift control pressure while the line pressure control system is functioning normally, and as a result, the shift operation in the normal state is performed. Of course, it is necessary to ensure that it does not affect the

Further, in this example, the line pressure solenoid 1
In the case where 4 is out of order, the constant pressure P _c from the pilot valve 15 is applied to the modifier valve 13 as it is, so that the maximum pressure of the line pressure control characteristics shown in FIG. 4 is adjusted. In the same condition as above, the line pressure will always be adjusted to the maximum pressure during failure. However, with the above-mentioned valve opening pressure of the relief valve 27, when an abnormality occurs in which the line pressure P _L remains at the maximum value as shown in FIG. Cannot inform the driver. That is, most of the required shift control pressure (P _S ) line at the time of the abnormality is at a level lower than the relief valve opening pressure, and therefore, even if the relief valve 27 is provided at the time of the abnormality, λ close to the maximum speed ratio. ₁
Only because the speed ratio on the higher speed side is not realized,
The driver cannot be informed of the failure. By the way, it is difficult for the driver to easily perceive the difference between whether or not the highest speed ratio is selected. This is the reason why the driver cannot be surely notified of the abnormality.

In order to solve this problem, the controller 17 of this embodiment is constructed so as to execute the control program of FIG. 2 in the shift control. That is, first in step S1,
The normal shift control described above with reference to FIG. 3 is executed. Then, in the next steps S2 and S3, the vehicle speed VSP is set to 7
It is determined whether or not 0 km / h or more and the throttle opening TVO is less than 3/8 of the set value, that is, whether or not the vehicle is in a traveling state in which the highest speed gear ratio is selected. In such a traveling state, it is determined whether or not the highest speed gear ratio command is output in step S4 corresponding to the highest speed gear ratio command detecting means. If the driving condition is not such that the highest speed gear ratio is selected, or if the highest speed gear ratio command is not output even in the driving condition that the highest speed gear ratio is selected, the control is terminated as it is. Then, the normal shift control in step S1 is continued.

In the traveling state in which the highest speed gear ratio is selected, while the highest speed gear ratio command is actually output, the output speed that can be determined from the vehicle speed VSP in step S5 corresponding to the actual speed ratio detection means. The actual speed ratio λ is calculated from the ratio of the input rotation speed N _i to the input speed N _i , and the deviation e between the actual speed ratio λ and the theoretical maximum speed ratio is calculated in step S6. In step S7 corresponding to the gear ratio abnormality detecting means, it is determined whether or not the gear ratio deviation e is equal to or less than the normal deviation e ₀ , and if it is equal to or less than the gear ratio command, the actual gear ratio matches the gear ratio command. ,
The control is ended as it is, and the normal shift control in step S1 is continued.

If it is determined in step S7 that the gear ratio deviation e exceeds the normal deviation e ₀ , step S7
In step 8, it is checked whether or not the timer TM for measuring the duration of this state has exceeded the set time TM ₀ , and TM ≥ TM
_When it becomes ₀ , in step S9 corresponding to the forced downshift transmission means, the continuously variable transmission is forcibly downshifted in place of the normal shift control in step S1. Naturally, this downshift is a downshift to a gear ratio lower than λ ₁ shown in FIG. 5B. As a result, the forced downshift gear shift is performed to a gear ratio on a much lower speed side than that, regardless of the traveling state in which the highest gear ratio should be selected, and the driver is informed of the above abnormality. It can be taught sensuously to prompt the repair of the failure.

[0033]

As described above, the shift control device for the V-belt type continuously variable transmission according to the first aspect of the present invention, as described in claim 1, has a relief valve connected to a line for guiding a shift control pressure to a pulley, and a line. When the line pressure control system fails in which the pressure remains the same upper limit value as the pressure of the pressure source, the continuously variable transmission cannot achieve at least a part of the gear ratio due to the opening pressure of the relief valve. Therefore, at the time of the above failure, some of the gear ratios cannot be achieved, so that the driver can feel the failure by feeling, and the driver can travel for a long time without knowing the failure and endure the V belt. It is possible to eliminate the problem that the property is significantly lowered.

According to a second aspect of the present invention, there is provided a shift control device for a V-belt type continuously variable transmission, wherein the relief valve opening pressure remains the same upper limit value as the line pressure as the pressure of the pressure source. Since the valve opening pressure was set lower than the shift control pressure when the line pressure control system failed, the continuously variable transmission was unable to perform shift control at the time of the failure, and the minimum speed ratio was maintained. As a result, the driver can know this at the same time as the failure, and the action and effect of the first invention can be made more remarkable.

When the line pressure control system fails in which the line pressure remains at the upper limit value of the hardware limit, the relief valves according to the first and second aspects of the invention provide the maximum speed ratio of the continuously variable transmission. Disable gear shifting. However, if it is impossible to change gears in such a high speed gear ratio range, it is difficult for the driver to recognize the failure. However, in the third invention, as in claim 3, a command for selecting the highest speed gear ratio is issued. Despite this, while the actual gear ratio is not the highest gear ratio, the downshift is forced to bring the gear ratio of the continuously variable transmission to the lower speed side, With this unnatural forced downshift, the driver can be sensuously informed of the abnormal line pressure, and the vehicle can run for a long time without being aware of this failure, significantly reducing the durability of the V-belt. It is possible to eliminate such a problem that the failure will occur.

According to a fourth aspect of the present invention, there is provided a shift control device for a V-belt type continuously variable transmission, wherein the line pressure remains at the upper limit of the hardware limit when the line pressure control system fails. In the above, since the continuously variable transmission is configured to forcibly downshift to a speed ratio lower than the maximum speed ratio that can be achieved by the presence of the relief valve, the forced downshift The driver can be more surely informed of the abnormal line pressure, and the operational effect of the third invention can be further ensured.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a shift control program executed by a controller in the same example.

FIG. 3 is a diagram showing a normal shift control pattern used for shift control in the same example.

FIG. 4 is a diagram showing a normal line pressure control characteristic together with a pump pressure which is an original pressure.

FIG. 5 (a) is a diagram showing a line pressure at an abnormal time when the line pressure is kept at a high value and a required shift control pressure at this time, and FIG. 5 (b) is a line pressure low value. FIG. 6 is a diagram showing a line pressure at the time of an abnormality that is kept held at and a required shift control pressure at this time.

[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 Vehicle speed sensor 19 Throttle opening sensor 20 Input rotation sensor 21 Speed change control valve 22 shift link 23 step motor 24 shifter 25 line pressure circuit 26 shift control pressure circuit P _L line pressure P _S shift control pressure

Claims (4)

[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 differential pressure between the transmission control pressure and the line pressure, the transmission control pressure is applied to the other pulley. In the leading conduit, the valve opening pressure is higher than the maximum value of the shift control pressure while the line pressure is normal, but the line pressure remains at the same upper limit value as the pressure of the pressure source. A shift control device for a V-belt type continuously variable transmission, wherein a relief valve having a valve opening pressure that causes an unachievable gear ratio is connected. 2. The valve opening pressure of the relief valve according to claim 1, which is lower than a shift control pressure at the time of a failure of the line pressure control system in which the line pressure remains the same upper limit value as the pressure of the pressure source. A shift control device for a V-belt type continuously variable transmission characterized in that a valve opening pressure is used. 3. The maximum speed ratio command detecting means for detecting that the selection command for the maximum speed ratio is issued, and the speed ratio detecting means for detecting the actual speed ratio according to claim 1 or 2. A gear ratio abnormality detecting means for detecting that the actual gear ratio is not the highest gear ratio even though a selection command for the highest gear ratio is issued in response to signals from both means, and the means. And a forced downshift transmission means for forcibly bringing the gear ratio to the low speed side in response to a signal from the gear shift control device of the V-belt type continuously variable transmission. . 4. The forced downshift transmission device according to claim 3, wherein when the line pressure control system fails, in which the line pressure remains at the upper limit value of the hardware limit,
A shift control of a V-belt type continuously variable transmission, which is configured to forcibly perform a downshift shift to a gear ratio lower than a maximum gear ratio that can be achieved by the presence of the relief valve. apparatus.