JP4293768B2 - Shift control device for continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device for a V-belt type continuously variable transmission, and more particularly to preventing malfunction of the continuously variable transmission by detecting slippage of the V-belt.
[0002]
[Prior art]
The V-belt type continuously variable transmission has a V-belt as a power transmission element between two pulleys, a primary pulley and a secondary pulley, and changes the groove width of these pulleys to change the rotational speed ratio of each pulley, that is, The speed change operation is performed by changing the ratio.
[0003]
If the V-belt slips for some reason, the gear ratio fluctuates, causing a difference between the desired gear ratio (target gear ratio) and the actual gear ratio (actual gear ratio) according to the driving state. This may lead to malfunction of the continuously variable transmission itself.
[0004]
In order to detect the slip of the V-belt, conventionally, for example, when the actual speed ratio deviates from the maximum or minimum speed ratio on the transmission mechanism, it is based on the deviation between the target speed ratio and the actual speed ratio. In some cases, it is determined that belt slip has occurred when the obtained shift speed deviates from the maximum shift speed on the transmission mechanism (see Patent Document 1).
[0005]
[Patent Document 1]
JP 62-68142 A (pages 2-5)
[0006]
[Problems to be solved by the invention]
However, in practice, there is no belt slip that is so large that the actual gear ratio is greater than or equal to the maximum gear ratio on the mechanism of the automatic transmission or less than the minimum gear ratio. It has been found that belt slippage occurs and the durability of the belt is reduced by this minute belt slippage. Therefore, a means for detecting the slip of the belt at an earlier stage is required from the viewpoint of fail-safe.
[0007]
Even if the actual transmission gear ratio of the automatic transmission is an intermediate transmission gear ratio, the present invention enables the belt slippage to be detected and dealt with early and reliably by detecting the belt slippage. It is an object of the present invention to solve the above problems by avoiding malfunctions in advance.
[0008]
[Means for Solving the Problems]
For these purposes, a continuously variable transmission control device according to the present invention is as described in claim 1.
A V-belt is stretched between the primary pulley on the input side and the secondary pulley on the output side that is directly connected to the drive source,
By setting the speed change actuator to the operating position corresponding to the target speed ratio, the V groove width of both pulleys is changed by the differential pressure between the primary pulley pressure and the secondary pulley pressure created using the line pressure as the original pressure, and the primary In the V-belt continuously variable transmission in which the actual gear ratio obtained from the rotation speed ratio of each of the pulley and the secondary pulley becomes the target gear ratio,
A signal value obtained by filtering the actual gear ratio with a 10 Hz high-pass filter, calculating an effective value of the signal after the filter process and converting it to an absolute value, and smoothing the signal converted to the absolute value It determined that but is determined that there is variation in the high frequency of the actual speed ratio when a predetermined value or more, the variation in the high frequency of the actual gear ratio is sliding on the V-belt when the predetermined time or longer has occurred Belt slip detecting means, and when the belt slip detecting means determines that slippage has occurred in the V belt, the belt slip detecting means includes an integrating means for integrating the duration of the high-frequency fluctuation of the actual gear ratio. when the integrated value of the duration of the fluctuations of the high frequency of the actual gear ratio by means exceeds a predetermined value, performing the V-belt protection control for regulating said V belt transmitting torque larger than a predetermined value It is an feature.
[0009]
【The invention's effect】
According to the continuously variable transmission control device of the present invention, in a V-belt type continuously variable transmission, when a change in the actual transmission ratio is detected at a high frequency, and the change in the actual transmission ratio continues for a predetermined time, the belt slip occurs. Judge that it occurred.
[0010]
As a result, a minute belt slip at an intermediate speed ratio between the maximum speed ratio and the minimum speed ratio can be detected quickly and reliably, and it can be effectively dealt with, so the transmission itself This malfunction can be avoided in advance.
[0011]
The transmission control device for a continuously variable transmission according to the present invention further includes integration means for integrating the duration of the actual gear ratio variation when the belt slip detection means determines that slippage has occurred in the V-belt. , when the integrated value of the duration of the variation of the actual speed ratio by the integrating means exceeds a predetermined value, performing V-belt protection control for regulating said V belt for transmitting torque of a predetermined value or more. As a result, it is possible to reliably avoid the malfunction of the transmission itself when the V-belt slips and the influences thereof.
[0012]
Furthermore, in a preferred embodiment of the transmission control device for a continuously variable transmission according to the present invention, the upper limit value of the output torque of the drive source is regulated as the V-belt protection control as described in claim 2 and claim 3. Control may be performed, or control for restricting an upper limit value of the rotational speed of the drive source may be performed. As a result, it is possible to more reliably avoid the malfunction of the transmission itself when the V-belt slips and the influences thereof.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 schematically shows the configuration of a V-belt type continuously variable transmission 1, and this V-belt type continuously variable transmission 1 has a primary pulley 2 and a secondary pulley 3 arranged so that their V grooves are aligned. The V belt 4 is stretched over the V grooves of the pulleys 2 and 3. An engine 5 that is a drive source is arranged coaxially with the primary pulley 2, and a lockup torque converter 6 and a forward / reverse switching mechanism 7 are sequentially provided between the engine 5 and the primary pulley 2 from the engine 5 side.
[0015]
The forward / reverse switching mechanism 7 includes a double pinion planetary gear set 7a as a main component, and the sun gear is coupled to the engine 5 via the torque converter 6 and the carrier is coupled to the primary pulley 2. The forward / reverse switching mechanism 7 further includes a forward clutch 7b that directly connects between the sun gear and the carrier of the double pinion planetary gear set 7a, and a reverse brake 7c that fixes the ring gear. It is assumed that the input rotation that has passed through is transmitted to the primary pulley 2 as it is, and the input rotation that has passed through the torque converter 6 from the engine 5 is transmitted to the primary pulley 2 under reverse speed reduction when the reverse brake 7c is engaged.
[0016]
The rotation to the primary pulley 2 is transmitted to the secondary pulley 3 via the V belt 4, and the rotation of the secondary pulley 3 is then transmitted to the wheels (not shown) via the output shaft 8, the gear set 9 and the differential gear device 10. In order to make it possible to change the rotational transmission ratio (transmission ratio) between the primary pulley 2 and the secondary pulley 3 during the power transmission described above, one of the flanges forming the V-grooves of the primary pulley 2 and the secondary pulley 3 is The fixed flanges 2a and 3a are used, and the other flanges 2b and 3b are movable flanges that can be displaced in the axial direction. These movable flanges 2b and 3b are fixed by supplying a primary pulley pressure Ppri and a secondary pulley pressure Psec, which are generated by using a line pressure to be controlled as described in detail later as a source pressure, to the primary pulley chamber 2c and the secondary pulley chamber 3c. By energizing the flanges 2a and 3a, the V-belt 4 is frictionally engaged with the pulley flange to enable the power transmission between the primary pulley 2 and the secondary pulley 3. In the present embodiment, in particular, the pressure receiving areas of the primary pulley chamber 2c and the secondary pulley chamber 3c are made the same so that one of the pulleys 2 and 3 does not have a large diameter. Miniaturize the machine.
[0017]
When shifting, the V groove widths of both pulleys 2 and 3 are changed by the differential pressure between the primary pulley pressure Ppri and the secondary pulley pressure Psec generated corresponding to the target gear ratio, as will be described later. The target gear ratio can be realized by continuously changing the winding arc diameter of the V belt 4 with respect to 3.
[0018]
The outputs of the primary pulley pressure Ppri and the secondary pulley pressure Psec are output by the shift control hydraulic circuit 11 together with the output of the engagement hydraulic pressure of the forward clutch 7b to be engaged when the forward travel range is selected and the reverse brake 7c to be engaged when the reverse travel range is selected. The transmission control hydraulic circuit 11 performs control in response to a signal from the transmission controller 12. For this reason, the transmission controller 12 receives a signal from the primary pulley rotation sensor 13 that detects the primary pulley rotation speed Npri, a signal from the secondary pulley rotation sensor 14 that detects the secondary pulley rotation speed Nsec, and the secondary pulley pressure Psec. A signal from the secondary pulley pressure sensor 15 to detect, a signal from the accelerator opening sensor 16 to detect the accelerator pedal depression amount APO, a selection range signal from the inhibitor switch 17, and an oil temperature to detect the shift operating oil temperature TMP A signal from the sensor 18 and a signal (engine speed and fuel injection time) related to the transmission input torque from the engine controller 19 that controls the engine 5 are input.
[0019]
The shift control hydraulic circuit 11 and the transmission controller 12 are as shown in FIG. 2. First, the shift control hydraulic circuit 11 will be described below. This circuit comprises an oil pump 21 driven by the engine, from which the medium of the hydraulic oil to the oil passage 22, which pressure is regulated to a predetermined line pressure P _L by the pressure regulator valve 23. The line pressure P _L of the oil passage 22 is adjusted by the pressure reducing valve 24 on the one hand and supplied to the secondary pulley chamber 3c as the secondary pulley pressure Psec, and is adjusted by the speed change control valve 25 on the other hand to be the primary pulley pressure Ppri as the primary pulley pressure Ppri. Supplied to 2c. Incidentally, the pressure regulator valve 23 controls the line pressure P _L by the drive duty input into a solenoid 23a, pressure reducing valve 24, and controls the secondary pulley pressure Psec by driving duty to a solenoid 24a.
[0020]
The speed change control valve 25 has a neutral position 25a, a pressure increase position 25b, and a pressure reduction position 25c. The speed change control valve 25 is connected to the middle of the speed change link 26 in order to switch these valve positions. A step motor 27 as a speed change actuator is connected to one end of 26, and a movable flange 2b of a secondary pulley is connected to the other end. The step motor 27 is moved from the reference position to the operation position advanced by the number of steps corresponding to the target gear ratio, and the operation of the step motor 27 causes the speed change link 26 to swing around the connecting portion with the movable flange 2b. Thus, the shift control valve 25 is changed from the neutral position 25a to the pressure increasing position 25b or the pressure reducing position 25c. As a result, the primary pulley pressure Ppri is increased with the line pressure P _L as the original pressure, or is reduced by the drain, and the differential pressure with the secondary pulley pressure Psec is changed, so that the upshift to the Hi side gear ratio or Lo A downshift to the side gear ratio occurs, and a gear shift operation toward the target gear ratio is performed.
[0021]
The progress of the speed change is fed back to the corresponding end of the speed change link 26 via the movable pulley 2c of the primary pulley, and the speed change link 26 is connected to the step motor 27 as a fulcrum, and the speed change control valve 25 is set to the pressure increasing position 25b. Or, it swings in a direction to return from the decompression position 25c to the neutral position 25a. Thus, when the target speed ratio is achieved, the speed change control valve 25 is returned to the neutral position 25a, and the target speed ratio can be maintained.
[0022]
Whether the solenoid drive duty of the pressure regulator valve 23, the solenoid drive duty of the pressure reducing valve 24, and the shift command (step number Step) to the step motor 27 supply the engagement hydraulic pressure to the forward clutch 7b and the reverse brake 7c shown in FIG. The transmission controller 12 is determined together with the control of whether or not, and the controller 12 is composed of a pressure control unit 12a and a transmission control unit 12b as shown in FIG. The pressure control unit 12a determines the solenoid drive duty of the pressure regulator valve 23 and the solenoid drive duty of the pressure reducing valve 24, and the shift control unit 12b determines the number of drive steps Astep of the step motor 27 as follows.
[0023]
That is, first, the speed change control unit 12b obtains the target input speed based on the planned speed change map using the vehicle speed that can be obtained from the secondary pulley speed Nsec and the accelerator pedal depression amount APO, and divides this by the secondary pulley speed Nsec. it allows obtaining the target speed change ratio corresponding to operating conditions (the vehicle speed and the accelerator pedal depression amount AP O). Next, the actual speed ratio is calculated by dividing the primary pulley speed Npri by the secondary pulley speed Nsec, and the actual speed ratio is set at the target speed while compensating for disturbance according to the deviation of the actual speed ratio with respect to the target speed ratio. A speed ratio command for asymptotically approaching the target speed ratio is obtained. Then, the step number of the step motor 27 (operating position of the step motor 27) Astep for realizing this speed ratio command is obtained, and this is commanded to the step motor 27 to achieve the target speed ratio by the speed change operation. be able to.
[0024]
Next, FIG. 3 is a flowchart showing a processing procedure for performing belt slip detection and shift control for coping with it in the present invention. The procedure will be described below.
[0025]
First, in step S101, it is determined whether or not the gear ratio control for the transmission is performed by feedback (F / B) control. Specifically, 1) the gear ratio, that is, whether or not the actual gear ratio obtained by dividing the rotational speed Npri of the primary pulley 2 by the rotational speed Nsec of the secondary pulley 3 is being controlled, and 2) the actual gear ratio. It is determined whether feedback control is being performed by determining whether the ratio can be detected, and 3) whether each pulley is rotating. In other words, in this step, it is determined whether or not the shift control is correctly performed on the transmission. If it is determined that feedback control is not being performed, the process is terminated. If it is determined that feedback control is being performed, the process proceeds to the next step S102.
[0026]
In the following step S102, it is determined whether or not a high frequency fluctuation has occurred in the actual gear ratio. If it is determined that no high frequency fluctuation has occurred, the process is terminated. If it is determined that a high frequency fluctuation has occurred, the process proceeds to step S103. The processing procedure for detecting the occurrence of this high frequency fluctuation will be described in detail later.
[0027]
In step S103, when it is determined that a high-frequency fluctuation has occurred in the actual gear ratio, it is determined whether or not the vibration continues for a predetermined time (in this case, 0.2 seconds). Here, if the duration of the high frequency fluctuation is less than or equal to the predetermined time, it is determined that it is a high frequency fluctuation caused by driving on a rough road, for example, other than a minute belt slip. Exit. On the other hand, if the duration of the high frequency fluctuation exceeds the predetermined time, it is determined that a minute belt slip has occurred, and the process proceeds to step S104.
[0028]
In step S104, the duration of the high frequency fluctuation that has occurred in the actual gear ratio (provided that it has exceeded 0.2 seconds as described above) is integrated, and it is determined whether or not the value has exceeded the predetermined integration time. To do. The reason for accumulating the durations of the high frequency fluctuations is that the running performance is not deteriorated excessively. In other words, when a small belt slip is detected and the belt protection control is suddenly performed in step S105, which will be described later, the belt durability has not deteriorated to the extent that the belt transmission torque is regulated. Sexuality will deteriorate. Therefore, by setting a threshold value of a predetermined integration time, the belt protection control is performed when the belt durability has deteriorated to some extent, and the power performance is prevented from excessively decreasing. The predetermined integration time is set by experimentally obtaining in advance an integration time that can achieve both driving performance and safety, and is set to about 2 seconds, for example. If the integrated value is less than the predetermined integrated time, it is determined that the belt damage has not accumulated so much, and the process is terminated. On the other hand, if the integrated value is equal to or longer than the predetermined integrated time, it is determined that the durability of the belt has decreased, and the process proceeds to step S105.
[0029]
In step S105, an engine torque upper limit request value is transmitted to the engine controller 19 (see FIG. 1) as belt protection control based on the determination result that belt slip has occurred. Thereby, when a torque larger than the upper limit value is output, the engine torque is reduced (torque down). Thereafter, the process ends.
[0030]
FIG. 4 is a flowchart showing details of step S102 during the processing of FIG. 3, that is, the processing procedure for detecting that a high-frequency fluctuation has occurred in the belt. Next, this procedure will be described.
[0031]
First, in step S201, the actual gear ratio is detected, and the detected signal is filtered through a high-pass filter. The filter used here is second order and 10 Hz.
[0032]
Next, in step S202, the effective value of the signal subjected to the filtering process in the previous step S201 is calculated, and the absolute value of the signal is obtained. Further, in step S203, signal smoothing is performed using a first-order 4 Hz filter.
[0033]
In step S204, it is determined whether the value of the obtained signal is equal to or greater than a predetermined value. Here, the predetermined value is set to 0.01, for example, and if it is equal to or greater than this value, it is determined that a high-frequency fluctuation has occurred in the actual gear ratio. Therefore, if the signal after smoothing is less than a predetermined value, it is determined that no high frequency fluctuation has occurred, and the process is terminated, and if the signal is equal to or higher than the predetermined value, it is determined that high frequency fluctuation has occurred, In the next step S205, it is determined that a high frequency fluctuation has been detected, and the process is terminated.
[0034]
FIG. 5 shows the process of determining the high frequency fluctuation of the actual transmission ratio in the continuously variable transmission, that is, the occurrence of minute belt slip, the signal processing according to the processing procedure shown in FIG. 3 and FIG. It is a time chart which shows a process. Next, this will be described. In the figure, the change in the gear ratio from the top, the signal after smoothing the detected gear ratio fluctuation, the time change of the integrated value of the duration of the gear ratio fluctuation (high frequency fluctuation), and the processing result It shows a change in a fail (durability decrease due to minute belt slip) determination flag.
[0035]
First, looking at the gear ratio ip, the actual gear ratio changes from moment to moment following the change in the target gear ratio, but fluctuations occur during that period, that is, the periods t1 to t2, t3 to t4, and t5 to t6. You can see that
[0036]
Therefore, smoothing processing is performed on the fluctuations in each of these periods, and if the value (absolute value) is a predetermined value, here 0.01 or more, it is determined that high frequency fluctuations have occurred. Furthermore, the duration of the high frequency fluctuation, that is, the previous periods t1 to t2, t3 to t4 and t5 to t7 are integrated. Here, the period t1 to t2 was less than a predetermined value (0.2 seconds), so a minute belt It is determined that no slip has occurred and is not included in the accumulated time. On the other hand, the periods t3 to t4 and t5 to t7 are included in the accumulated time as being over a predetermined value.
[0037]
If the accumulated time exceeds a predetermined value (for example, about 2 seconds as described above), it is determined that the durability of the belt has decreased. In the figure, it is shown that the integration time exceeds the predetermined integration time at the intermediate time t6 between the periods t5 to t7.
[0038]
Based on this result, it is determined that the durability of the belt has decreased to some extent at the instant t6 when the integrated time exceeds the predetermined integrated time, and the value of the fail determination flag is set to a value from 0 to 1. Based on the value of the fail determination flag, transmission of a torque upper limit request value to the engine, that is, a torque down command is issued to the engine controller, and the torque is reduced.
[0039]
FIG. 6 is a flowchart showing another processing procedure for performing belt slip detection and shift control for coping with it in the present invention. In this process, steps S301 to S304 are the same as steps S101 to S104 in the flowchart of FIG. 3 described above. However, in step S305, as the belt protection control, the torque upper limit in step S105 of FIG. Instead of transmitting the request value, the engine rotation upper limit limit request value is transmitted. The upper limit value of the engine speed is limited based on the engine speed upper limit request value. Thereafter, the process ends.
[0040]
In this case, since the upper limit value of the engine speed is limited when the durability of the belt is reduced, it is possible to reliably regulate the torque of the engine that is the driving source, and the torque of the belt exceeding the predetermined value. Without being transmitted, the safety of the transmission without permission can be ensured, and the reliability is also improved.
[0041]
As explained above, in the transmission control device for a continuously variable transmission according to the present invention, since belt slip is detected based on a change in the actual frequency ratio at a high frequency, the difference between the maximum speed ratio and the minimum speed ratio is determined. Since it is possible to detect a minute belt slip at an intermediate gear ratio early and reliably, and to deal with it effectively, it is possible to avoid malfunction of the transmission itself in advance. .
[0042]
In particular, in the present invention, it is determined that a minute belt slip has occurred when the high-frequency fluctuation of the actual gear ratio continues for a predetermined time. However, it is possible to reduce the possibility of judging this fluctuation as the occurrence of minute belt slip, and to prevent the possibility of erroneous detection.
[0043]
In addition, the upper limit of the engine torque or the upper limit of the engine speed is used as a belt protection control for restricting the belt from transmitting a torque exceeding a predetermined value when the accumulated time of the belt high frequency fluctuation exceeds a predetermined accumulated time. Since the restriction is made, it is possible to achieve both driving performance and safety without excessively reducing the driving performance of the vehicle.
[0044]
In this case, the torque of the engine, which is the drive source, can be reliably regulated, and the belt does not transmit a torque exceeding a predetermined value, so that the safety of the continuously variable transmission itself can be ensured and the reliability can be improved. Become.
[0045]
In the above-described embodiment, the engine is used as a drive source. However, the present invention is not limited to this, and even when an electric motor is used as another drive source, Needless to say, the present invention can be applied even when a motor and an engine are used in combination.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a V-belt continuously variable transmission including a transmission control device according to the present invention, together with the transmission control system.
FIG. 2 is a block diagram showing details of the speed change control system of FIG. 1;
FIG. 3 is a flowchart showing an example of a processing procedure for performing belt slip detection and control for coping with it according to the present invention.
4 is a flowchart showing a processing procedure of a subroutine for detecting occurrence of a high-frequency fluctuation of the belt in FIG. 3;
5 is a time chart showing a process until a change in speed ratio, signal processing based on the processing procedure shown in FIG. 3 based on the change, and occurrence of belt slip are determined. FIG.
FIG. 6 is a flowchart showing another example of a processing procedure for performing belt slip detection and control for coping with it according to the present invention.
[Explanation of symbols]
1 V belt type continuously variable transmission
2 Primary pulley
3 Secondary pulley
4 V belt
5 Engine
6 Lock-up torque converter
7 Forward / reverse switching mechanism
8 Output shaft
9 Gear set
10 Differential gear unit
11 Shift control hydraulic circuit
12 Transmission controller
13 Primary pulley rotation sensor
14 Secondary pulley rotation sensor
15 Secondary pulley pressure sensor
16 Accelerator position sensor
17 Inhibitor switch
18 Oil temperature sensor
19 Engine controller
21 Oil pump
23 Pressure regulator valve
24 Pressure reducing valve
25 Shift control valve
26 Speed change link
27 Step motor (shifting actuator)

Claims (3)

A V-belt is bridged between the primary pulley on the input side and the secondary pulley on the output side that is directly connected to the drive source,
By setting the speed change actuator to the operation position corresponding to the target speed ratio, the V groove width of both pulleys is changed by the differential pressure between the primary pulley pressure and the secondary pulley pressure created using the line pressure as the original pressure, and the primary In the V-belt type continuously variable transmission in which the actual gear ratio obtained from the rotation speed ratio of each of the pulley and the secondary pulley becomes the target gear ratio,
The actual gear ratio is filtered by a high-pass filter of 10 Hz, the effective value of the signal after the filter process is calculated and converted into an absolute value, and the signal value obtained by smoothing the signal converted to the absolute value It determined that but is determined that there is variation in the high frequency of the actual speed ratio when a predetermined value or more, the variation in the high frequency of the actual gear ratio is sliding on the V-belt when the predetermined time or longer has occurred Belt slip detection means for
The belt slip detecting means, when it is determined that slip has occurred in the V-belt, comprising an integrating means for integrating the duration of the high-frequency fluctuation of the actual gear ratio,
When the integrated value of the duration of the high frequency fluctuation of the actual gear ratio by the integrating unit becomes equal to or greater than a predetermined value, V belt protection control is performed to restrict the V belt from transmitting torque exceeding the predetermined value. A transmission control device for a continuously variable transmission. The apparatus of claim 1 .
As the V-belt protection control, a control for regulating the upper limit value of the output torque of the drive source is performed. The apparatus of claim 1 .
As the V-belt protection control, a control for regulating the upper limit value of the rotational speed of the drive source is performed.

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