JPH03144157A - Line pressure control for continuously variable transmission - Google Patents

Abstract

PURPOSE:To secure the smooth traveling feeling by comparing the aimed line pressure at this time and the aimed line pressure in the preceding time in each prescribed carrying out cycle and filter-processing with different filter coefficient in accordance with the case where the aimed line pressure at this time is over the aimed line pressure in the preceding time or below the aimed line pressure. CONSTITUTION:In a control part 82, an aimed line pressure PLINSP at this time and an aimed line pressure PLNSPL which is calculated in the preceding time are comparison-judged in each prescribed cycle, and if PLINSP>PLINSPL, the UP side filter coefficient is selected, while if PLINSP<PLINSPL, the DOWN side filter coefficient is selected. After selecting each filter coefficient, the filter processing for the aimed line pressure PLINSP at this time is carried out, and the calculated aimed line pressure at this time is memorized as the aimed line pressure PLINSPL in the preceding time so as to be set as the comparison value in the next time. Accordingly, since the line pressure can be controlled finely, smooth traveling feeling can be secured.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a line pressure control method for a continuously variable transmission.
In particular, the present invention relates to a line pressure control method for a continuously variable transmission in which a target line pressure is controlled to be filtered using a filter coefficient.

[Prior Art] In a vehicle, a transmission is interposed between an internal combustion engine and drive wheels. This transmission changes the driving force and running speed of the drive wheels in accordance with the widely varying running conditions of the vehicle, thereby allowing the internal combustion engine to fully demonstrate its performance. The transmission includes a fixed pulley part fixed to the rotating shaft and a movable pulley part attached to the rotating shaft so as to be able to approach and separate from the fixed pulley part. There is a continuously variable transmission that transmits power by increasing or decreasing the rotation radius of a belt wrapped around a pulley by increasing or decreasing the width of the groove, thereby changing the speed ratio (belt ratio). Examples of this continuously variable transmission include, for example, JP-A-57-186656, JP-A-59-43249, and JP-A-59-7.
It is disclosed in Japanese Patent Application Laid-open No. 7159 and Japanese Patent Application Laid-open No. 81-233258.

A line pressure control method for a continuously variable transmission is disclosed in Japanese Patent Application Laid-Open No. 64-44341. The line pressure control method for a continuously variable transmission disclosed in this publication detects the actual oil pressure only within a predetermined range when the line pressure and clutch pressure become equal after transitioning from start mode to drive mode. , the correction amount is calculated from the actual oil pressure signal, the throttle opening signal, and the previous correction amount by learning control, and when shifting to open loop control, the target line pressure is corrected according to the correction amount, and the line Eliminates pressure fluctuations.

[Problems to be Solved by the Invention] By the way, in conventional line pressure control methods for continuously variable transmissions, open-loop control at the time of starting or closed-loop control during normal running is performed.

In the case of both loop controls mentioned above, the target line pressure is calculated according to the operating condition using the throttle angle, engine speed, and target clutch pressure, in order to eliminate noise and maintain continuity with the target value. After calculation, the target line pressure is filtered and set as the final target line pressure.

Thereafter, a drive duty is output to the solenoid for line pressure control from calculations of open loop control or closed loop control for the target line pressure, and the line pressure is controlled to a predetermined pressure value.

Also, when a quick line pressure response is required, such as when shifting the shift lever from the D range position to the L range position, or when stepping on the throttle during starting or acceleration, and when the ratio changes smoothly during normal driving. The filter coefficient of the target line pressure is set to one value in order to meet two situations, such as a case where the response of the line pressure may be relatively slow.

Therefore, by setting one filter coefficient, when both of the above two situations are not satisfied, especially when a sudden downshift is required, line pressure responsiveness deteriorates and belt slip occurs. There is a disadvantage that clutch slip may occur.

[Purpose of the Invention] Therefore, the purpose of the present invention is to compare the current target line pressure and the previous target line pressure at each predetermined period, so that the current target line pressure is equal to the previous target line pressure, in order to eliminate the above-mentioned disadvantages. Different filter coefficients are used depending on whether the current target line pressure is above the line pressure or when the current target line pressure is less than the previous target line pressure.
By controlling the filter processing using each filter coefficient, the filter coefficients are changed according to the change in the current target line pressure, and the filter processing is performed using these filter coefficients. For example, when downshifting while driving, the line pressure It can improve responsiveness, reliably prevent clutch slip and belt slip, and
To realize a line pressure control method for a continuously variable transmission capable of finely controlling line pressure and ensuring smooth running feeling.

[Means for Solving the Problems] In order to achieve this object, the present invention provides two pulley parts including a fixed pulley part and a movable pulley part attached to the fixed pulley part so as to be able to move toward and away from the fixed pulley part. In a line pressure control method for a continuously variable transmission, in which the line pressure of a continuously variable transmission is controlled to change the speed ratio by increasing or decreasing the rotation radius of the belt wound around both pulleys by decreasing or increasing the width of the groove between the pulleys, Compare the line pressure with the previous target line pressure, and set the filter coefficient differently depending on whether the current target line pressure is greater than or equal to the previous target line pressure or if the current target line pressure is less than the previous target line pressure. The filter processing is controlled by each filter coefficient.

[Function] As described above, the current target line pressure and the previous target line pressure are compared at each predetermined period, and if the current target line pressure is greater than or equal to the previous target line pressure, or the current target line pressure is If the target line pressure is less than the previous target line pressure, the filter coefficient is changed according to the change in the current target line pressure, and filter processing is performed using this filter coefficient.
For example, when downshifting while driving, line pressure responsiveness is improved to reliably prevent clutch slip and belt slip, and line pressure is finely controlled to ensure a smooth driving feeling.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

1 to 4 show embodiments of this invention. Fourth
In the figure, 2 is, for example, a belt-driven continuously variable transmission;
2A is a belt, 4 is a drive pulley, 6 is a drive side fixed pulley part, 8 is a drive side movable pulley part, 10 is a driven side boo 1ha, 12 is a driven side fixed pulley part, and 14 is a driven side pulley part. This is a side movable pulley piece. The drive side pulley 4 is a fourth
As shown in the figure, a drive-side fixed pulley part 6 is fixed to the rotating shaft 16, and a driving-side movable bobbin part is mounted on the rotating shaft 16 so as to be movable in the axial direction of the rotating shaft 16 but not rotatable. 8. Further, similarly to the driving pulley 4, the driven pulley 10 also has a driven side fixed pulley part 1.
2 and a driven side movable pulley piece 14.

First and second housings 18.20 are attached to the drive side movable pulley piece 8 and the driven side movable pulley piece 14, respectively, and first and second hydraulic chambers 22.24 are formed, respectively. . At this time, a biasing means 26 made of a spring or the like is provided in the second hydraulic chamber 24 on the driven side to bias the second housing 20 in the direction of expansion of the second hydraulic chamber 24.

An oil pump 28 is provided on the rotating shaft 16, and the oil pump 28 is connected to the first and second hydraulic chambers 22,24.
The first oil passages 30 and 30 communicate with each other through second oil passages 30 and 32, and a primary pressure control valve 34, which is a speed change control valve, that controls a primary pressure, which is an input shaft sheave pressure, is interposed in the middle of the first oil passage 30. In addition, a line pressure (generally 5 to 25 kg/C
112) to a constant pressure (3 to 4 kg/c+s2), and a first three-way solenoid valve 42 for primary pressure control is communicated with the primary pressure control valve 34 through a fourth oil passage 40. .

Further, a line pressure control valve 4 having a relief valve function for controlling the line pressure, which is the pump pressure, is disposed in the middle of the second oil passage 32.
4 is communicated through a fifth oil passage 46, and a second three-way solenoid valve 50 for line pressure control is communicated with this line pressure control valve 44 through a sixth oil passage 48.

Furthermore, a clutch pressure control valve 52 for controlling clutch pressure is installed in the seventh oil passage 5 in the middle of the second oil passage 32 on the side of the second hydraulic chamber 24 than the communicating portion of the line pressure control valve 44.
4, and a third direction solenoid valve 58 for clutch pressure control is connected to this clutch pressure control valve 52 through an eighth oil passage 56.
Communicate.

Further, the primary pressure control valve 34, the first solenoid valve 42 for primary pressure control, the constant pressure control valve 38, the sixth oil passage 48, the second solenoid valve 50 for line pressure control, and the clutch pressure control valve 52 are connected to a ninth oil The passages 60 communicate with each other.

The clutch pressure control valve 52 is communicated with the hydraulic start clutch 62 through a tenth oil passage 64, and a pressure sensor 68 is communicated with the tenth oil passage 64 through an eleventh oil passage 66. This pressure sensor 68 can directly detect the oil pressure when controlling the clutch pressure in hold and start modes, and contributes to instructing the detected oil pressure to be the target clutch pressure. Furthermore, since the clutch pressure becomes equal to the line pressure in the drive mode, it also contributes to line pressure control.

An input shaft rotation detection gear 70 is provided on the outside of the first housing 18.
A first rotation detector 72 on the input shaft side is provided near the outer peripheral portion of the input shaft rotation detection gear 70. Further, an output shaft rotation detection gear 74 is provided on the outside of the second housing 20, and a second rotation detector 76 on the output shaft side is provided near the outer peripheral portion of the output shaft rotation detection gear 74. Then, detection signals from the first rotation detector 72 and the second rotation detector 76 are outputted to a control section 82, which will be described later, to determine the engine rotation speed and belt ratio.

The hydraulic start clutch 62 is provided with an output transmission gear 78, and a third rotation detector 80 for detecting the rotation of the final output shaft is provided near the outer periphery of the gear 78. In other words, this third
The rotation detector 80 detects the rotation of the final output shaft directly connected to the reduction gear, the differential, the drive shaft, and the tires.
Vehicle speed can be detected. Further, the second rotation detector 7
6 and the third rotation detector 80, the hydraulic starting clutch 6
It is also possible to detect rotations around 2, which contributes to detecting the amount of clutch slip.

Furthermore, various conditions such as a throttle opening of a carburetor (not shown) of the vehicle, engine rotation from the first to third rotation detectors 72, 76, 80, vehicle speed, etc. are input, and the duty ratio is changed to perform gear change control. The controller 82 controls the first three-way solenoid valve 42 and constant pressure control valve 38 for primary pressure control, the second three-way solenoid valve 50 for line pressure control, and the third three-way solenoid valve 58 for clutch pressure control. It is configured to control the opening/closing operation and also control the pressure sensor 68. Further, in detail, the functions of various signals and input signals input to the control section 82 are as follows: (1) Shift lever position detection signal... Each range signal such as Pl R1N1 Dl L etc. Required line pressure and ratio, clutch control, carburetor throttle opening detection signal...
Detects the engine torque from the memory input into the program in advance, determines the target ratio or target engine speed, detects the carburetor idle position, and improves accuracy in correction and control of the carburetor throttle opening sensor. , Accelerator pedal signal: Detects the driver's intention based on the state of depression of the accelerator pedal and determines the direction of control when driving or starting ■, Brake signal: Detects the driver's intention based on the state of depression of the accelerator pedal. Detects the presence and determines the control direction such as clutch disengagement■, Power mode option signal...It is used as an option to make the performance of the vehicle more sporty (or more economical).

The primary pressure control valve 34 has a spool valve that reciprocates within a body (not shown).

In addition, the control unit 82 compares the current target line pressure and the previous target line pressure at every predetermined period, and if the current target line pressure is equal to or higher than the previous target line pressure, the current target line pressure is It has a configuration in which filter coefficients are made different depending on the previous case where the line pressure is less than the target line pressure, and control is performed so that filter processing is performed using each filter coefficient.

More specifically, the target line pressure PLINSP is set for each mode such as hold, normal start, special start, drive, and coast. In other words, in the hold mode, the target line pressure PLINSP is a fixed value, in the normal start mode, the target line pressure PL I NSP is a map value based on the throttle opening, and in the special start mode, the target line pressure PLINSP is a calculated value based on the belt ratio. In the drive mode, the target line pressure PLINSP is a calculated value based on the engine torque and belt ratio, and in the coast mode, the target line pressure PLINSP is a fixed value.

Also, set the target line pressure PLINSP to 20 m5, for example.
It is set by a basic calculation loop for each ec.

Then, the control section 82 controls the current target line pressure PLI.
Previous target line pressure PLINSP when NSP was calculated last time
The current target line pressure PLIN, which is the target value, is compared with L.
When SP is greater than or equal to the previous target line pressure PLINSPL, the filter coefficient is changed to 5H2, and the current target line pressure PLINSP is equal to the previous target line pressure PLIN.
If there is no SPL groove, the filter coefficients are changed to 0.5Hz, and the current target line pressure PLINS is set to the final target line pressure PLINSPF using these filter coefficients.
This controls the filter processing of P.

Furthermore, the calculated current target line pressure PLINSP is stored as the previous target line pressure PLINSPL, and is used as the next comparison value.

Note that the reference numeral 84 is a piston of the hydraulic start clutch 62;
86 is an annular spring; 88 is a first pressure coupler; 9
o is a friction plate, 92 is a second pressure plate,
94 is an oil pan, and 96 is an oil filter.

Next, the effect will be explained.

As shown in FIG. 4, in the belt-driven continuously variable transmission 2, an oil pump 28 located on the rotating shaft 16 operates in response to the drive of the rotating shaft 16, and the oil is pumped into an oil pan 94 at the bottom of the transmission. is absorbed through the oil filter 96. The line pressure, which is this pump pressure, is controlled by the line pressure control valve 4.
4, the amount of leakage from this line pressure control valve 44,
In other words, if the amount of relief from the line pressure control valve 44 is large, the line pressure will be low, and if it is small, the line pressure will be high.

Next, electronic control of the belt-driven continuously variable transmission 2 will be explained.

Continuously variable transmission 2 is hydraulically controlled, and in response to commands from control unit 82, appropriate line pressure for belt retention and torque transmission, primary pressure for changing gear ratio, and clutch engagement are ensured. Clutch pressure is secured for each.

The explanation will be made along the control flowchart of the belt-driven continuously variable transmission 2 shown in FIG.

An engine rotation control program for the belt-driven continuously variable transmission 2 is started by driving an internal combustion engine (not shown) (
The current target line pressure PLINSP is compared with the previous target line pressure PLINSPL calculated last time.
102) Do.

In this comparative judgment (102), the current target line pressure P
If LINSP is greater than or equal to the previous target line pressure PLINSPL, select the UP side filter coefficient and set the filter coefficient to 5Hz (104), and set the current target line pressure PLI.
If NSP does not have the previous target line pressure PLINSPL, select DOWN (III) and set the filter coefficient to 0°5Hz (10B).

After selecting each filter coefficient, the current target line pressure PLINSP is filtered (108L
The calculated current target line pressure PLINSP is stored as the previous target line pressure PLINSPL to be used as the next comparison value (110).

Thereafter, open loop processing is performed (112), and it is determined whether or not closed loop control is being performed (114).

If this judgment (114) is YES, the clutch pressure P
After performing closed loop processing (116) by CLU, calculation is performed to convert the pressure into a duty value (118)
If the judgment (114) is No, the process directly proceeds to calculation (11B) to convert the pressure into a duty value. Then, the calculated duty value is outputted to control the line pressure (120), and the line pressure control program is returned (122).

The control flowchart of the above-mentioned belt-driven continuously variable transmission 2 is illustrated as a block diagram as shown in FIG.

Furthermore, if the UP side is selected and the filter coefficient is set to 5Hz, the target line pressure PLINSP is set as shown in Fig. 3(a).
Final target line pressure PLINSPF with quick response to
So, select the DOWN side and set the filter coefficient to 0.5H.
z, the target line pressure P is as shown in Fig. 3(b).
The final target line pressure PLINSPF is slow in response to LINSP.

As a result, when the current target line pressure PLINSP is greater than or equal to the previous target line pressure PL lN5PL, the UP side filter coefficient is selected and the filter coefficient is set to 5Hz, and the current target line pressure PLINSP is set to the previous target line pressure. If it is less than PLINSPL, the filter coefficient on the DOWN side can be selected to set the filter coefficient to 0.5Hz.The filter coefficient can be changed according to the change in the current target line pressure PLINSP, and the filter processing can be performed using the filter coefficient. For example, it is possible to improve the responsiveness of line pressure during downsist while driving, and it is possible to reliably prevent clutch slip and belt slip.
Line pressure can be controlled finely and a smooth running feeling can be ensured.

Moreover, if the UP side is selected and the filter coefficient is set to 5Hz, the final target line pressure PLINSPF is quickly responsive to the target line pressure PLINSP, and the DOWN
If you select the side and set the filter coefficient to 0.5Hz, the third
As shown in Figure (b), the final target line pressure PLINSPF has a slow response to the target line pressure PLINSP.
As a result, ratio changes are smooth when a quick response of line pressure is required, such as when shifting the shift lever from the D range position to the H range position, when stepping on the throttle during starting or accelerating, and during normal driving. The filter coefficient of the target line pressure can be set to suit two situations, such as when the responsiveness of the line pressure may be relatively slow, which is practically advantageous.

Furthermore, since the problem can be dealt with only by changing the software in the control section 82, it is easy to implement, the configuration does not become complicated, the manufacturing cost can be kept low, and it is economically advantageous. It is.

Note that the present invention is not limited to the above-described embodiments, and various modifications can be made.

For example, in the embodiment of the present invention, the filter coefficient is UP regardless of each mode such as hold, normal start, special start, drive, and coast.
The user can select either 5Hz on the side or 0°5Hz on the DOWN side, but the filter coefficients can be increased for each mode.
It is also possible to perform fine line pressure control for wood grain by setting the side and the DOWN side.

[Effects of the Invention] As explained in detail above, according to the present invention, the current target line pressure and the previous target line pressure are compared at every predetermined cycle, and the current target line pressure is determined to be higher than or equal to the previous target line pressure. The filter coefficients should be different depending on the case where the current target line pressure is less than the previous target line pressure, and the filter processing should be performed using each filter coefficient.
By changing the filter coefficient according to the change in the target line pressure, and performing filter processing using the filter coefficient, it is possible to improve the responsiveness of the line pressure when downshifting while driving, for example, and ensure clutch slip and belt slip. The line pressure can be precisely controlled and a smooth running feeling can be ensured. In addition, since it can be handled by simply changing the control software, it is easy to implement, the configuration does not become complicated, and manufacturing costs can be kept low.
It is also economically advantageous.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, FIG. 1 is a flowchart for controlling a belt-driven continuously variable transmission, and FIG. 2 explains target line pressure control of the belt-driven continuously variable transmission. The block diagram, Figure 3 (a) is a schematic diagram explaining filter processing using filter coefficients when the current target line pressure is higher than the previous target line pressure, and Figure 3 (b) is a schematic diagram illustrating the filter processing using the filter coefficient when the current target line pressure is higher than the previous target line pressure. FIG. 4 is a block diagram of a belt-driven continuously variable transmission. In the figure, 2 is a belt-driven continuously variable transmission, 2A is a belt, 4 is a driving pulley, 10 is a driven pulley, 3
0 is the first oil passage, 32 is the second oil passage, 34 is the primary pressure control valve, 36 is the third oil passage, 38 is the constant pressure control valve, 40 is the fourth oil passage, 42 is the first three-way solenoid valve, 44 46 is the line pressure control valve, 46 is the sixth oil passage, and 48 is the line pressure control valve.
is the sixth oil passage, 50 is the second three-way solenoid valve, 52 is the clutch pressure control valve, 54 is the seventh oil passage, 56 is the eighth oil passage, 58 is the third three-way solenoid valve, 60 is the ninth oil passage, 62 is a hydraulic starting clutch, 64 is a 10th oil passage,
66 is an eleventh oil passage, 68 is a pressure sensor, 72 is a first rotation detector, 7th is a second rotation detector, 80 is a third rotation detector, and 82 is a control section.

Claims (1)

[Claims] 1. The radius of rotation of the belt wound around both pulleys can be increased by decreasing or increasing the groove width between the fixed pulley piece and the movable pulley piece that is attached to the fixed pulley piece so as to be able to move toward and away from the fixed pulley piece. In a line pressure control method for a continuously variable transmission that performs speed change control to increase or decrease the gear ratio, the current target line pressure and the previous target line pressure are compared at every predetermined cycle,
The filter coefficients are made different depending on whether the current target line pressure is greater than or equal to the previous target line pressure or when the current target line pressure is less than the previous target line pressure, and control is performed to perform filter processing using each filter coefficient. A line pressure control method for a continuously variable transmission characterized by: