JPH02154856A - Hydraulic control device for automatic transmission - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for an automatic transmission, and more particularly, to a hydraulic control device for an automatic transmission that can alleviate shock during gear shifting. [Prior art 1] A hydraulic control device for an automatic transmission has a cylinder-piston structure between a shift valve that switches gears and a frictional engagement device, which can adjust transient hydraulic pressure when the frictional engagement device is engaged. An accumulator is provided. This accumulator maintains the oil pressure supplied to the frictional engagement device at a set oil pressure for a predetermined period of time to reduce shock during gear shifting. The optimal value of this set oil pressure changes depending on the engine torque or engine load input to the automatic transmission. Further, this set oil pressure can be controlled by changing the oil pressure applied to change the back pressure of the accumulator. In view of these points, Japanese Patent Application Laid-Open No. 130653/1983 includes a solenoid valve for controlling the back pressure of the accumulator, and also adjusts the ON-OFF duty ratio of this solenoid valve to the throttle opening. A method has been proposed to precisely control the accumulator backpressure. However, in this technology, the duty-next pressure guided to the accumulator back pressure control valve in response to the throttle opening is uniquely determined, so when the throttle opening is determined, the accumulator back pressure changes. There was a problem in that the oil pressure was completely fixed at a specific value, and therefore the oil pressure set by the accumulator was also fixed at a specific value (see FIGS. 8(A) to 8(D)). In other words, in reality, even if the throttle opening is the same, engine torque varies greatly depending on factors such as engine speed, intake temperature, and intake pressure (or boost pressure), so the determined accumulator back pressure may not necessarily be appropriate. There was a problem. Regarding this problem, for example, Japanese Patent Application Laid-Open No. 61-149657
The countermeasures are disclosed in the publication. In other words, this measure means that when controlling the back pressure of the accumulator, it is not only the throttle opening that is controlled, but also various factors such as automatic transmission oil temperature, engine intake air temperature, engine rotation speed, supercharging pressure, etc. This allows for more detailed control. However, as mentioned above, no matter how many parameters indicating vehicle driving conditions and driving environment conditions are taken in,
In hydraulic control, there are and will always be variations and changes over time that cannot be predicted at the design stage. For example, even if the throttle opening, engine speed, intake temperature, intake pressure, etc. are the same, engine torque changes due to changes in the engine itself over time, and as a result, the shift characteristics change. Variations in the dimensions and ease of movement of each valve and accumulator in an automatic transmission naturally affect hydraulic characteristics, but even if tuned at the time of manufacturing, these variations will change over time. . Furthermore, if the oil in the automatic transmission deteriorates or is contaminated with impurities that affect the flow of oil, the shifting characteristics will also change. Furthermore, Fig. 9 shows the traveling distance and the dynamic friction coefficient μ of the frictional engagement device.
As shown in the relationship with d, W! As the frictional engagement device becomes worn out and the dynamic friction coefficient μd decreases, shifting characteristics will begin to show that are significantly different from the initial state. Therefore, since there are such uncertain factors, if the accumulator back pressure is uniquely determined by various parameters such as throttle opening, it is not necessarily possible to always achieve the same speed change characteristic. In view of these conventional problems, the applicant first attempted to accurately control the back pressure of the accumulator, including the uncertain variations inherent to the vehicle that occur during manufacturing or over time, and to always achieve the best results. In order to provide an invention that can maintain the speed change characteristics, Japanese Patent Application No. 62-308188 (Unknown). The invention is an automatic gear shift system that controls the transient hydraulic pressure of a friction engagement device by electronically controlling the back pressure of such an accumulator according to the value of a parameter that can estimate the magnitude of a gear shift shock. In the hydraulic control system of the machine, the shift time is detected, and the electronic control method for the parameter value in the subsequent shift is learned and corrected in accordance with the detected shift time. As a result, even if the parameter values are the same, the electronic control will be sequentially learned to take into account the actual shift time, and changes over time that cannot be grasped with the parameters that are constantly being captured. be able to respond appropriately. Since this invention does not perform feedback correction of the accumulator back pressure in real time, the calculation speed does not need to be very fast, and the invention uses learning to control the accumulator back pressure most appropriate to the current situation, that is, the frictional engagement device. It was possible to execute engagement transient hydraulic pressure control. [Problems to be Solved by the Invention] However, in the case of the present invention, for a specific shift (for example, a shift from the first gear to the second gear, a shift from the second gear to the third gear, etc.) The conventional method used was to set a target shift time for each engine load (e.g., throttle opening), and then learn and correct the set duty ratio for each engine load by comparing it with the actual shift time. If the engine load changes during the process, there is a problem in that the target shift time also changes accordingly. Regarding this point, the invention does not specifically mention at what point in time during a gear shift the learning correction of the duty ratio should be performed corresponding to the engine load; however, if the engine load is significantly different before and after the gear shift, Since the target shift time also varies greatly, there is a problem in that appropriate learning correction may not be possible in some cases. The present invention has been made in view of these problems, and takes into consideration the possibility that inappropriate learning correction will not be performed even if the engine load changes significantly before and after shifting. An object of the present invention is to provide a hydraulic control device for an automatic transmission that can always perform good control of engagement transient hydraulic pressure.

[Means for Solving the Problem J] The present invention, as summarized in FIG. In a hydraulic control device for an automatic transmission that is electronically controlled, the method includes a means for detecting a gear shift time, and learns and corrects the electronic control method for the value of the parameter in a subsequent gear shift depending on the gear shift interval. The above object is achieved by comprising means for detecting the engine load, and means for canceling the learning correction when the change in the engine load before and after the shift is equal to or greater than a predetermined value i. . [Operations and Effects of the Invention] In the present invention, the transient oil pressure during the engagement of the frictional engagement device is basically determined according to the value of a parameter that can estimate the magnitude of the shift shock, such as the engine torque. . Then, the shift time is detected, and the electronic control method for the parameter value in subsequent shifts is learned and corrected in accordance with the detected shift time. Furthermore, the degree of change in engine load before and after the gear shift is detected, and if this change is large, the learning control is stopped. As a result, the learning correction is performed only when the engine load is substantially constant, that is, when the gear shift is performed in a stable state, and inappropriate learning correction is prevented from being performed. In addition, as a result of executing learning correction, even if the parameter values are the same, corrections are performed sequentially so that electronic control takes into account the actual shift time, and it is not possible to use only the parameters that are constantly captured. It becomes possible to appropriately respond to changes over time that cannot be grasped. Note that the engagement transient oil pressure of the frictional engagement device can be controlled, for example, by electronically controlling the back pressure of the accumulator. In this case, the so-called so-called electromagnetic valve may be of a type that controls the duty ratio, or it may be of a type that uses an electromagnetic proportional valve that can change the output oil pressure according to the load current.

【Example】

Embodiments of the present invention will be described in detail below based on the drawings. FIG. 2 shows an overall outline of an automatic transmission system for a vehicle to which an embodiment of the present invention is applied. This automatic transmission includes a torque converter section 20 and an overdrive mechanism section 40 as its transmission sections.
and an underdrive enclosure 60 with three forward stages and one reverse stage. The torque converter section 20 is of a well-known type and includes a pump 21, a turbine 22, a stator 23, and a lock-up clutch 24. The overdrive mechanism section 40 includes a set of planetary gears consisting of a sun gear 43, a ring gear 44, a planetary pinion 42, and a carrier 41, and the rotational state of this planetary gear is controlled by a clutch CO, a brake Bo, and a one-way clutch. It is controlled by Fo. The underdrive structure part 60 is a common spring gear 6.
1. Ring gear 62.63, planetary onion 64.
65 and carriers 66 and 67, and the rotation state of the two sets of planetary gear devices and the connection state with the overdrive mechanism are controlled by the clutch C1,
C2, brakes B1 to B3, and one-way clutch F+,
It is controlled by F2. Since this transmission unit itself is well known, the specific connection state of each component will only be shown in a skeleton diagram in FIG. 2, and detailed explanation will be omitted. This automatic transmission includes a transmission section as described above,
and a computer 84. The computer 84 includes a throttle sensor 80 that detects the throttle opening θ to reflect the output (torque) of the engine 1, and a vehicle speed N.
a sensor 82 (rotational speed sensor of the output shaft 70 of the automatic transmission) for detecting the speed change, and a drum of the clutch CG, which is selected as a member whose rotational speed changes when the speed change is performed, in order to detect the speed change time. rotational speed N c
Each signal from the sensor 99 and the like is input. The rotational speed of the clutch Go is equal to the turbine rotational speed during the first to third speeds, and is zero during the fourth speed. The Go rotational speed changes significantly as the speed change is executed. Therefore, C. By detecting the rotational speed Nco, the start and end of the shift can be detected, and as a result, the shift time can be detected. Upon receiving these signals, the computer 84 changes the 1! By driving and controlling the magnetic valves S1 and $2 (for shift valves) and SL (for lock-up clutch), and executing the combination of engagement of each clutch, brake, etc. as shown in Fig. 3. , basic shift control of each gear stage is performed using a known method. Also, a duty solenoid 104.1 is used to control accumulator back pressure.
Drives and controls 06. FIG. 4 shows the main parts of the hydraulic control circuit 86. In the figure, numeral 102 is a duty modulator valve, 104.106 is a duty solenoid, and 108.1
10 is a damper, 112 and 114 are accumulator control valves, and 116 and 118 are accumulators for controlling the transient hydraulic pressure for engaging the clutch 02% brake B2. The duty modulator valve 102 has a well-known configuration and reduces the line pressure PL to a constant pressure PL+. This constant pressure PL1 is the duty solenoid 10
The supply pressure will be 4.106. The duty solenoids 104 and 106 reduce the constant pressure PL1 by turning on and off at high speed at intervals according to the duty ratio commanded by the computer 84, and generate duty control pressures PS+ and PS2. Therefore, the duty control pressures PS1 and PS2 are maintained at predetermined values determined by the duty ratios, regardless of changes in the line pressure PL. The dampers 108 and 110 are connected to the duty solenoid 104.
．． Duty control pressure Ps accompanying high-speed on-off of 106
i, Absorb PS2 pulsation. The duty control pressures PS+ and PSz are guided to accumulator control valves 112 and 114, respectively, and the line pressure PL is adjusted to the duty control pressure PS+ in a well-known manner.
, PSz is regulated and controlled according to the value of accumulator 116.11 as accumulator back pressure PA+, PA2.
As is clear from FIG. 3, when shifting from the first gear to the second gear, for example, the brake B2 is engaged, but at this time the accumulator The back pressure PA2 is optimized by learning correction and controlling the duty ratio of the duty solenoid 106. Hereinafter, this learning control of the shift from the first gear to the second gear will be explained in detail. FIG. 5 shows an example of the basic duty ratio with respect to the throttle opening. That is, in response to the throttle opening signal input from the throttle opening sensor 80, the computer 84 sets the basic duty ratio as shown in FIG. Control of the duty solenoid 106 is started based on the ratio.The horizontal axis may be any parameter that represents the engine load, such as intake pipe negative pressure, intake air amount, etc.
Naturally, engine torque is also acceptable. FIG. 6(A) is an example of a change in the rotational speed of the clutch Co during a shift from the first gear to the second gear. In order to understand this gear shift time,
It is determined that the shift starts at the time ^, and the end of the shift is determined at the time . In this case, the time required for actual gear shifting, ie, actual gear shifting time tR, is determined by (tB-t^). From this actual shift time TR, the duty solenoid 106
Correct the duty ratio. DSSD 1-DSSD 1 + (1-t*/tK
)XDSSDlB ・・・・・・(1) Here, D
SSDl is the duty ratio of the duty solenoid 106, [K is the basic (ideal) shift time determined in advance for shifting from the first gear to the second gear, and 08SDIB is a correction coefficient. This correction coefficient DSSD1B is designed to change depending on the throttle opening degree. DSSD1 uses the basic duty ratio shown in FIG. 5 in the initial state (the backup RAM of the computer 84 has also been cleared!g). The corrected duty ratio DSSD1 is stored in the backup RAM in the computer 84 to be used as the duty ratio at the next time of shifting from 1 to 2 with the same throttle opening. When changing the opening degree from 1 to 2, the corrected value becomes the initial value. The duty ratio DSSD1 is also corrected during the 1st to 2nd shift, and becomes the updated value each time. Similar corrections are made for other speed changes, such as those in which clutch C2 is engaged. As a result, variations in engine torque, changes over time, and hydraulic control m
Variations in each valve, etc. of the device, their changes over time, and recommendations for frictional engagement devices! Regardless of variations in the characteristics of the friction coefficient μd, changes over time, etc., when the same type of speed change and the same throttle opening are used, the same speed change characteristics can always be obtained. Such a learning correction is executed only when the throttle opening degree hardly changes before and after the gear change. The reason for this is that if the throttle opening changes before and after a shift, the basic (ideal) shift time tK will differ depending on the point of change, the degree of change, etc., so the correction of the duty ratio DSSDI will not always be appropriate. This is because you will no longer be able to do it. FIG. 10 illustrates an example of this problem. For example, if we consider a shift from the first gear to the second gear, the shift starts at time t^ and ends at tB, but during that time the throttle opening changes from θS to θ.
It has changed to e. Therefore, the task of determining whether the throttle opening degree of the relevant shift was actually between θS and θe (the target shift time tK is between θS and θe)
(Which throttle opening corresponds to the one between
lK) It becomes very vague as to which duty ratio ossoi to adjust XDSSolB to or from which throttle opening degree corresponds. Therefore, there is no guarantee that the learning correction is equivalent to a shift that occurs with a constant throttle opening, and there is a risk that the learning itself will be meaningless. Therefore, in this embodiment, the correction by learning is executed only when the variation width Δθ shown in FIG. 10 is less than or equal to the predetermined value Δθ1. That is, if the throttle opening changes before and after the shift, the learning correction is canceled. As a result, learning is performed only in gear shifts where the throttle opening is kept in a steady state during gear shifting, so the above-mentioned problems are eliminated and accurate learning correction is performed. Note that canceling the learning correction simply means that the correction for the duty ratio DSSD1 will not be updated based on the special gear shift, and the disadvantage of canceling the learning correction is that the correction will be updated inappropriately. This is much smaller than the disadvantages that may arise. FIG. 7 shows a flowchart of the above control. In this flowchart, a shift from the first gear to the second gear is taken as an example. In FIG. 7(A), when there is a decision to shift from the first gear to the second gear, the solenoid S1 for performing the gear shift is driven (step 151), and a 1→2 gear shift is in progress. Flag Fo is set to 1 (step 152). FIG. 7(B) shows a duty ratio correction routine that is different from the main routine regarding shift determination. In step 201, it is determined whether Fo=1. If Fo=O (speed change from 1 to 2 is not in progress), this routine exits. If Fo=1, proceed to step 2o2. In steps 202 to 208, it is determined whether the actual speed change has already started, that is, whether the rotational speed change of the clutch Co has started (whether the above-mentioned t^ has been reached). This determination is made, for example, when the actual Go rotational speed (=turbine rotational speed) Nco is smaller than the Co rotational speed Nco1 at the first gear stage by a predetermined rotational speed N^ (Nco 1- N^
) is determined to be smaller than 01 times in a row. The Co rotation speed Ncol at the first gear is 1 → 2
Since the shift point (vehicle speed) is determined for each throttle opening, once the throttle opening is determined, it is determined from that shift point (vehicle speed) and the gear ratio of the first gear. Predetermined rotation speed NA
This mainly takes into consideration the correspondence error between the throttle opening and the 1→2 shift point (vehicle speed). The reason for confirming that 01 times are repeated is mainly to prevent detection errors. Specifically, in step 202, N co < N co
It is determined whether 1-N^ is established. When this condition is satisfied, the process proceeds to step 203, and a flag F1 indicating whether the condition is satisfied for the first time is determined. Since this flag F1 is initially set to zero, step 2
Proceed to 04. At 204, flag F1 is set to 1. Thereafter, in step 205, the number of detections n^ is set to 1. When it is reset and comes to step 202 again, N c
When it is determined that the condition o < N co 1- N^ is satisfied again, this time it is determined as Fl-1 in step 203, so the process proceeds to step 206, and the number of detections n^ becomes 0.
It is determined whether the value is 1 or more. Since this nl is generally set to about 2 to 4 times, a "NO" determination is initially made, and the number of detections n^ is incremented in step 207. In this way N c
o < N co 1 Every time N^ is detected continuously, the number of detections n^ is incremented. If the condition is not established even by − degrees, F1 is set to 0 in step 202A, so the number of times of detection n^ is set to 1 again when the next condition is established. When the number of detections n^ reaches 01, it is determined that the shift has started, that is, time t^ has arrived, and the process proceeds to step 208. In step 208, the determination flag F2 is checked to determine whether or not the determination in step 206 is rYEsJ for the first time. This flag F2 is initially set to F+=0. Therefore, the process first proceeds to step 209, sets F2-1, determines and stores ^ at the time shown in FIG. 6, and determines and stores the throttle opening θS at that time (step 210
). Specifically, at time t^, counter Tl11 is started. This counter Tm is the computer 84
is incremented by a scheduled interrupt. In steps 212 to 217, it is determined whether or not the shift has been completed, that is, whether or not the above-mentioned period has been reached. The basic procedure is the same as steps 202 to 207 described above. However, the determination of the end of the shift is based on the Co rotation speed N C
This is done depending on whether it is determined n2 times in succession that o is smaller than a value (NCO2+N9) that is larger than the Go rotational speed N co 2 at the second gear by a predetermined rotational speed NEI. Once the throttle opening is determined, the Co rotational speed N co 2 in the second gear is determined from the 1→2 gear shift point (vehicle speed) and the gear ratio of the second gear. The predetermined rotational speed NO mainly takes into consideration the correspondence error between the throttle opening and the 1→2 shift point (vehicle speed). The reason for confirming that the detection has occurred n2 times in a row is mainly to prevent detection errors. Flag E3 of step 213 has the same meaning as flag F1 of step 203, and step 212A has the same meaning as step 202A. Further, "ne increment" in step 217 has the same meaning as "n^ increment" in step 207. In this way, when it is determined that the condition of N co < N co 2 + N days has been satisfied 02 times in a row, the process proceeds to step 218, where the day is determined and stored as the time, and the throttle opening degree θe at that time is is confirmed and memorized. Specifically, at time ta, incrementing of the counter Tll set in step 210 is stopped at this stage. In step 219, the shift time tR is determined. Specifically, this is done by checking the count number of the counter T1 that was incremented between time 1B and time [^]. After the shift time tR is determined, the process proceeds to step 219A, where the difference Δθ(-θS) in throttle opening before and after the shift is calculated.
-θS) is smaller than a predetermined value Δθ1. When IΔθ≦Δθ1, it is determined that the shift was executed in a stable state with little change in throttle opening, and the process proceeds to step 220, where the duty ratio DSSD1 is corrected based on the above-mentioned equation (1). . Then, in step 221, the flag F o = F
Clear 3. On the other hand, if 1Δθ1>Δθ1, it is determined that the shift has a large change in throttle opening before and after the shift, and step 220 is bypassed. Therefore, learning correction is not performed. Thereafter, in step 221, the flag F o ''=F 3 is cleared. When it is determined to shift from 1 to 2 according to the above flow, the shift start timing t^ is determined in step 210, and,
In step 218, the end date of the gear shift is determined. Thereafter, the duty ratio DSSD1 is corrected based on the shift time tR only when it is determined that the shift has been stable. In this way, each time a 1st → 2nd shift occurs in a stable state, the duty ratio DSSD
1 is corrected, and as a result, the shift characteristics are brought closer to an ideal state. For shifting from 2nd gear to 3rd gear, clutch C2
Learning control of the duty ratio is performed using a similar procedure. In this embodiment, neither duty control nor learning control is performed for the shift from the third gear to the fourth gear. This is because the shift shock from the third gear to the fourth gear is originally small. However, in the present invention, learning control may also be performed for the third to fourth gears.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the gist of the present invention, and FIG. 2 is a block diagram showing the gist of the present invention.
A schematic block diagram of a vehicle automatic transmission to which an embodiment of the present invention is applied, FIG. 3 is a diagram showing the operating state of the frictional engagement device in the automatic transmission, and FIG. 4 is a diagram showing the operating state of the frictional engagement device in the automatic transmission. Fig. 5 is a hydraulic circuit diagram showing the main parts of the hydraulic control system of
A diagram showing the relationship between throttle opening and basic duty ratio, Figure 6 is a diagram showing changes in the rotational speed of clutch Co, and Figures 7 (A) and (8) are diagrams showing the relationship between the throttle opening and the basic duty ratio. Flowchart showing the control flow for correction, FIG. 8 (A
) to (D) are diagrams showing the relationship between each parameter in a conventional accumulator back pressure control device, and FIG. 9 is a diagram showing the relationship between the travel distance and the dynamic friction coefficient of the friction material of the friction engagement device. 10 are shift characteristic diagrams illustrating problems that occur when the throttle opening changes before and after the shift. 104.106...Duty solenoid, 112.
114...Accumulator control valve, 116.118...Accumulator, No. ...Rotational speed of clutch Co, tR...shift time, DSSDI...duty ratio, DSSDlB...correction coefficient, Δθ...difference in throttle opening before and after shifting, Δθ,...
・Predetermined value. Figure 3 Figure ◎EF r3 $bFfa>a+4v #3 Figure 5 Muiδ kiy1 Figure 10 No. 4 1° ν8YaYaIppen5

Claims (1)

[Claims] (1) In a hydraulic control device for an automatic transmission in which the engagement transient hydraulic pressure of a friction engagement device is electronically controlled according to the value of a parameter that can estimate the magnitude of a shift shock, means for detecting shift time. a means for learning and correcting the electronic control method for the value of the parameter in a subsequent shift according to the shift time; a means for detecting an engine load; A hydraulic control device for an automatic transmission, comprising: means for canceling the learning correction.