JP2850250B2 - Transmission control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a shift control device for an automatic transmission.

[Prior art]

Conventionally, provided with a gear transmission mechanism and a plurality of friction engagement devices,
A shift control device for an automatic transmission configured to selectively switch engagement of a friction engagement device by operating a hydraulic control device to achieve one of a plurality of shift speeds is already widely known. I have. In addition, a technique has been proposed in which a good gear shift characteristic is maintained by performing feedback control of an engagement pressure of a friction engagement device during gear shifting. (For example, see JP-A-63-
12137). This feedback control detects the rotational speed of a member whose rotational speed changes as the shift is executed, for example, the rotational speed of a member such as a turbine shaft in an automatic transmission, a drum of each clutch or brake, or an engine. The feedback control of the engagement pressure of the friction engagement device in the automatic transmission is performed so that the rotation speed changes along the locus of the target rotation speed to be followed by the member after the shift output. When such feedback control is employed, the engagement pressure of the frictional engagement device is not necessarily the same as the vehicle-specific variation that has occurred during manufacture or over time, and the rotational speed of the member always corresponds to the locus of the target rotational speed. , So that good shifting characteristics can always be obtained.

[Problems to be solved by the invention]

However, since this feedback control is performed based on the rotational state of a member whose rotational speed changes due to a gear shift, the feedback control is performed until the rotational member undergoes a rotational change due to the gear shift (inertia phase). Until the start), there is a problem that the feedback control cannot be performed. Conventionally, the supply of hydraulic pressure until the rotating member starts to change the rotational speed depends on the type of shift or running parameters such as throttle opening that reflects the engine load, and is controlled by a map or the like. The value was to be determined. However, as described above, the hydraulic system of an automatic transmission always has a vehicle-specific variation that occurs at the time of manufacture or over time, and therefore, even if the traveling parameters are the same, that is, the type of shift and the throttle. Even if the opening degree is the same, the generated hydraulic pressure is not necessarily the same. Therefore, depending on the variation, the hydraulic pressure (engagement pressure) supplied to engage the friction engagement device
The initial value of greatly deviates from the optimum value, and the feedback control may be started, and an extremely large engagement pressure correction may be performed to eliminate the deviation. Further, in an extreme case, a deviation of the hydraulic pressure occurs that cannot be corrected with the correction amount after the feedback control is started, and the rotation locus of the rotating member cannot be matched with the intended target rotational speed locus. There were also problems. The present invention has been made in view of such a conventional problem, and regardless of a vehicle-specific variation occurring at the time of manufacture or over time, an optimum engagement pressure is set from the beginning of hydraulic supply. It is an object of the present invention to provide a shift control device for an automatic transmission which can supply and smoothly change the trajectory of the rotating member along the trajectory of the target rotational speed, and can always maintain an optimal shift characteristic.

[Means for Solving the Problems]

As shown in FIG. 1, the present invention provides a shift control device for an automatic transmission configured to maintain good shift characteristics by performing feedback control of an engagement pressure of a friction engagement device during shifting. Means for determining an initial value at the time of starting the feedback control of the engagement pressure based on a traveling parameter of the vehicle, etc.
In the feedback control of the engagement pressure during the previous shift,
Means for detecting the time until the inertia phase starts,
Means for correcting the initial value of the current engagement pressure based on the time until the inertia phase starts is provided, thereby achieving the above object. Further, the present invention provides a shift control device for an automatic transmission configured to maintain good shift characteristics by controlling an engagement pressure of a friction engagement device during a shift, wherein the shift control device includes: Means for determining an initial value at the time of starting the control of the engagement pressure, means for training the time until the inertia phase starts in the control of the engagement pressure at the time of the previous shift, and the start of the inertia phase Means for correcting the initial value of the current engagement pressure on the basis of the time until the above.

[Action]

According to the present invention, when the initial value of the engagement pressure is determined basically depending on the traveling parameters of the vehicle, for example, the type of shift, the throttle opening, etc., the determined initial value is determined. Is corrected based on the time until the inertia phase starts in the feedback control of the engagement pressure at the time of the previous shift. For example, in the previous shift control, when the initial value is low due to various variations, the time until the inertia phase of the shift starts should have been long. Moreover, the length of time until the start of the inertia phase is
It should be different depending on how much the initial value deviates from the optimal value. Therefore, the initial value of the current engagement pressure can be appropriately corrected by checking the time until the inertia phase in the previous shift starts.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, in order to control the engagement pressure of the friction engagement device, the back pressure of the accumulator is controlled. In addition, a turbine shaft is selected as a member whose rotational speed changes when a shift is performed. Fed back control of the engagement pressure is performed Te cowpea that actual turbine circuit speed NT is electronically controlled linear solenoid (S _D) to along connexion change the trajectory of the turbine target rotation speed NT _0. The turbine target circuit speed NT ₀
Is the turbine rotation speed at the start of the shift, N _S , the target shift time (the target value of how many seconds the shift takes from start to end), T _S , and the turbine synchronous rotation speed after the shift, NT _D (= automatic transmission) If the output shaft rotation speed n ₀ × gear ratio i _H after shifting and the time t at the start of shifting are set to zero, the target rotation speed NT after t sec
₀ (t) is obtained by NT ₀ (t) = {(N _S −NT _D ) / T _S } × t + N _S (1) Among these, the target shift time T _S is called from the map according to the throttle opening. or,
N _S , n ₀ , and t use values at that time. FIG. 2 shows an overall outline of an automatic transmission for a vehicle to which this embodiment is applied. This automatic transmission has a torque converter section 20 as a transmission section and an overdrive mechanism section 40.
And an underdrive mechanism 60 having three forward stages and one reverse stage. The torque converter section 20 includes a pump 21 and a turbine 2
2. It is a well-known device having a stator 23 and a lock-up clutch 24. The overdrive mechanism section 40 includes a sun gear 43, ring gear 44, planetary pinions 42, and includes a pair of planetary gear unit consisting of Kiyariya 41, clutch C ₀ the rotation state of the planetary gear device, the brake B _0, the one-way by the clutch F ₀ are connexion control. The underdrive mechanism 60 includes a common sun gear 6
1, two sets of planetary gear units consisting of ring gears 62, 63, planetary pinions 64, 65 and carriers 66, 67. The rotational state of these two sets of planetary gears and the state of connection with the overdrive mechanism are determined by clutch C. _1, C _2, the brake B ₁ ~
B ₃ and one-way clutches F ₁ and F ₂ . Since the transmission unit is well known per se, the specific connection state of each component is only shown in the skeleton in FIG. 2 and detailed description is omitted. This automatic transmission includes a transmission unit as described above and a computer (ECU) 84. The computer 84 has a throttle sensor 80 for detecting a throttle opening θ for reflecting the output (torque) of the engine 1, a vehicle speed sensor (rotation speed sensor of the output shaft 70) 82 for detecting a vehicle speed n ₀ , and a shift transient. NT sensor 99 for detecting the rotational speed NT of the turbine 22 of the automatic transmission for reflecting the state
Are input. The computer 84 controls the solenoid valves S ₁ , S ₂ (for the shift valve) and SL in the hydraulic control circuit 86 in accordance with a preset throttle opening-vehicle speed shift map.
(For lock-up clutch), and the shift is executed by engaging and engaging each clutch / brake as shown in FIG. FIG. 4 shows a main part of the hydraulic control circuit 86. In the figure, reference symbol _SD is a linear solenoid, 108 is an accumulator control valve, 110 is a modulator valve, 112 is an accumulator, and 114 is a shift valve. In this figure, the brake B ₂
Are representatively shown. As is clear from FIG.
Brake B ₂ is a friction engagement device is engaged when achieving a shift to the second speed stage from the first speed stage. Using a hydraulic pressure generated by an oil pump (not shown) as a base pressure, a line pressure PL is generated by a known method. This line pressure PL is applied to the port 110A of the modulator valve 110. Modulator valve 110 has a line pressure PL
Receiving the specified modulator pressure Pm in a well-known manner
Occurs at 110B. Linear solenoid S _D generates a solenoid pressure PS ₁ corresponding receiving this Mojiyureta pressure Pm to the difference between the turbine speed NT and the turbine target rotation speed NT ₀ in a known manner.
That is, as described above, the computer
Is input. This turbine rotation speed
NT is compared with a turbine target rotational speed NT ₀ preset according to the engine torque and the type of shift. For example, in the case of a 1 → 2 shift, the execution of the 1 → 2 shift lowers the turbine rotational speed NT. If the turbine rotational speed NT is lowered earlier than the target rotation speed NT ₀ (the case of NT-NT ₀ <0), since that would progress of the shift is too fast, reducing the engagement transition oil pressure of the brake B ₂ This NT-NT ₀
Load current command based on duty ratio corresponding to is applied to the linear solenoid S _D, the linear solenoid S _D is to generate the solenoid pressure PS ₁ in accordance with the load current in a known manner. In this embodiment, when the duty ratio increases (10
It approaches 0%, the), and summer as solenoid pressure PS ₁ is increased to be generated. The solenoid pressure PS ₁ is input to the port 108A of Aki Yumu regulator control valve 108. Aki Yumu regulator control valve 108, the solenoid pressure PS ₁ from the line pressure PL ₁ and linear solenoid S _D as an input signal, pressure regulating the line pressure PL ₂ ports 108B to the accumulator back pressure Pas. In other words, accumulator backpressure Pac is basically the line pressure PL ₂ in other words is pressurized by connexion adjusted the force of the line pressure PL ₁ and the spring 108C, and, by connexion corrected solenoid pressure PS ₁ of the linear solenoid S _D It was done. It should be noted that the accumulator back pressure Pac has a characteristic of decreasing as the duty ratio increases. When the shift determination (in this case, the shift from the first speed to the second speed) is performed by the computer 84, the solenoid valve S ₁
The shift valve 114 is switched in a known manner via
The line pressure PL (P _B0) begins to be aerodrome supplied to the brake B _2. The setting of the oil pressure at the start of the supply is a major feature of this embodiment. This will be described later in detail. In response to this supply, the piston 112A of the accumulator 112
Begins to rise. While the piston 112A is increasing, pressure (P _B0) is supplied to the brake B _2, maintained at a downward force and balance ivy substantially constant hydraulic pressure acting on the downward biasing force and the piston 112A of the spring 112B Will be done. The force that attempts to push the piston 112A downward is due to the back pressure P acting on the back pressure chamber 112C of the accumulator 112.
Generated by ac. Therefore, the accumulator back pressure
Mogi Yu regulator valve 110 as described above to pac, to arbitrarily control the transient pressure P _B0 upon engagement of the linear solenoid S _D and Aki Yumu regulator control Yotsute brake B ₂ to be controlled via a valve 108 It becomes possible. Specifically, when the duty ratio is further increased (closed to 100%), the engagement pressure is further reduced. Linear solenoid S _D, as described above, to be controlled in dependence on the difference between the turbine rotational speed NT and the turbine target rotation speed NT _0, after all, by such hydraulic system, the turbine rotational speed NT turbine target the rotational speed NT ₀ can be fed back controlled so that along connexion changes. By the way, even if there is a variation during manufacture or a change with time between the vehicles, the feedback control is performed after the rotation speed change due to the rotation member shift, that is, after the start of the inertia phase (after the start of the feedback control). However, after the shift command is issued, the hydraulic pressure starts to be supplied, and the supply of the hydraulic pressure starts until the rotation member starts to change rotation (until the inertia phase starts). During this time, the feedback control cannot be performed, so when the initial value of the engagement pressure shifts to a higher or lower value due to various variations, the start of the inertia phase itself is abnormally early or late. I may get tired. In an extreme case, as shown in FIG. 8, for example, as shown in FIG. 8, the feedback control after the start of the inertia phase cannot sufficiently correct the engagement pressure, so that the gear shift ends within the buffer area K of the accumulator. However, the output shaft torque suddenly changes with the end of the buffer region K of the accumulator, and this is felt as a shift shock. The problem is that the initial value of the engagement pressure from the shift command to the start of the inertia phase is determined only by the traveling parameters (shift type and throttle opening), and the engine torque and the friction material of the friction engagement device are determined. Are not taken into account at all. Therefore, in order to solve this, it is only necessary to set the initial engagement pressure in consideration of various variations and changes over time. That is, when performing a certain shift, the same throttle opening that was performed before that is performed. It is determined whether or not the initial engagement pressure set at that time was appropriate based on the shift characteristics of the same shift type,
Based on the result, the initial engagement pressure of the shift to be performed this time may be learned and determined. The determination of the validity of the initial engagement pressure of the previously performed shift is performed based on the change mode of the correction amount (duty ratio) during the feedback control at that time. Of course, when the specifications at the time of gear shifting are very close to the set values and the gear shifting is normally performed by the initial engagement pressure set at the design stage, the change in the duty ratio during feedback control becomes very small. Also, the shift characteristics are improved. [Fifth
See figure]. However, as shown in FIG. 6, for example, when the set value of the initial engagement pressure is too low, a correction to reduce the duty and increase the engagement pressure is performed. The reason that the duty ratio is increased at the end of the shift is to reduce the engagement shock by reducing the engagement pressure when the friction engagement device is completely engaged. Conversely, if the initial engagement pressure is too high, a correction is made to increase the duty ratio and reduce the engagement pressure. Therefore,
Based on the magnitude and direction of the change in the duty ratio of the previous shift, it can be determined whether the initially set initial engagement pressure is too high, too low, or appropriate.
There can be various processes for correcting the initial duty ratio from the duty ratio change mode. In the apparatus of this embodiment, this is performed as follows. From the change in the duty ratio during the feedback control of the engagement pressure, the maximum value Dmax and the minimum value Dmin of the duty ratio appearing first are obtained. When the initial duty ratio is Ds, the initial duty ratio in the next shift is Dsn. For example, as shown in FIG. 7A, when Dmax = Ds, Dsn = Ds− (Ds−Dmin) × 0.5. Also, as shown in FIG. 7 (B), Dmax> Ds
In the case of, Dsn = Ds + (Dmax-Ds) x 0.5. FIG. 9 shows a flowchart of the above logic. Which of the shifts that have already been used as a reference for learning depends not only on the condition that the type of shift and the throttle opening are the same, but also on the timing of the shift and the conditions such as oil temperature. Is determined. For example, a shift performed at the time of extremely low oil temperature immediately after the start of the engine or a shift previously performed each time is not useful. Further, the learning of the initial engagement pressure does not necessarily refer to only one of the previously performed shifts, but may refer to several shifts, for example, by a weighted average. . In this embodiment, for example, as shown in FIG. 8, the initial engagement pressure is extremely low, so that the start of the inertia phase is extremely delayed, and the end of the buffer region K of the accumulator after the start of the inertia phase. At this point, it is considered that the shift has not yet been completed, and the shift has ended immediately due to the rapid rise of the hydraulic pressure together with the end of the buffer area K of the accumulator. It is in such a case,
This is because the speed of the feedback control is short, and the shift ends before the change in the duty ratio appears. Therefore, it is considered that the appropriateness of the initial engagement pressure cannot be determined only by the change mode of the duty ratio. Therefore, in this embodiment, the accumulator buffer region K
In such a case, the case where the start of the inertia phase is delayed so that the shift cannot be completed within that time is detected by measuring the time from the start of the shift to the start of the inertia phase, and a predetermined correction described later is performed. I'm sorry. The control flow shown in FIG. 9 is started when the necessity of the shift is determined based on the map of the vehicle speed and the throttle opening. First, in step 202, an initial duty ratio corresponding to an initial engagement pressure for engaging the friction engagement device is read from the map based on the type of the shift and the throttle opening. Further, a timer T is reset to measure the time until the inertia phase starts. In step 204, the initial engagement pressure is set, and the timer T starts counting as time elapses. In step 206, it is determined whether or not the inertia phase has started. This determination is made by detecting that the rotation speed NT of the rotating member in the automatic transmission, for example, the turbine shaft, has begun to decrease due to the start of engagement of the friction engagement device. More specifically, the turbine circuit speed NT
Whether (NT but it has decreased less than the rotational speed minus the constant .DELTA.N _t from the value obtained by multiplying the gear ratio i _L of pre-shift to the output shaft rotation speed n ₀
<N ₀ × i _L −ΔN). Until the inertia phase is started, the process returns to step 204 to continue applying the initial engagement pressure. When it is determined in step 206 that the inertia phase has started, the increment of the timer T until the start of the inertia phase is stopped in step 208, and the value Tsi at that time is stored. Step 210
, The feedback control of the friction engagement device is started. The specific method of the feedback control is as described above. During the feedback control, the maximum value Dmax and the minimum value Dm of the duty ratio are controlled.
When in is updated, it is rewritten each time. In step 212, it is determined whether or not the shift has reached the end. This determination is made as to whether or not the turbine rotation speed NT has become larger than a value obtained by subtracting a predetermined value ΔN ₂ from a value obtained by multiplying the output shaft rotation speed n ₀ by the gear ratio i _H after shifting, that is, NT> n ₀ ×
This is performed by determining whether or not i _H −ΔN ₂ is established. The feedback control in step 210 is continued until the shift is completed. When it is determined in step 212 that the shift has reached the end, the end control of the shift is executed in step 214. The end control of the shift means that the hydraulic pressure is temporarily reduced by increasing the duty reduction to the maximum, the transmission torque at the moment when the friction material of the friction engagement device is completely engaged is reduced, and the shift shock is performed. Is to be reduced. This shift end control is continued until the end of the shift is detected by step 216. The end of the shift is NT> n ₀ × i _H −ΔN ₃ (this is to eliminate the influence of the sensor system error and the pulsation of the rotation system, and is set to a value smaller than ΔN ₂ ). Judgment is made based on whether it is not. If it is determined that the shift has been completed, the routine proceeds to step 218 and thereafter, and enters a learning flow of the initial engagement pressure. First, the steps
Dmax rewritten during feedback control at 218
Is determined to be equal to the initial duty ratio Ds. If Dmax = Ds, the routine proceeds to step 220, where the duty ratio Dsn for generating the next initial engagement pressure is D.
It is corrected to s− (Ds−Dmin) × 0.5. On the other hand, when Dmax is equal to Ds, the routine proceeds to step 202, where the duty ratio Dsn for generating the next initial engagement pressure is Ds + (Dma
x−Ds) × 0.5. Thereafter, the process proceeds to step 224, and it is determined whether or not the time Tsi from when the shift command is issued to when the inertia phase starts is greater than a threshold value Tlim preset according to the stop opening and the type of shift. . If this time Ts
When i is smaller than the threshold value Tlim, there is no particular problem, so the next initial duty ratio Dsn is
(Step 228). However, if the time Tsi is larger than the threshold value Tlim, it means that the previous initial duty ratio Ds was too low to allow the shift to be completed within the buffer area of the accumulator, and therefore, step 226 is performed. The next initial duty ratio Dsn is set to a value which is smaller by a predetermined value Dst than Dsn obtained in step 220 or 222, and the next shift is started with a higher initial engagement pressure. In this manner, the manner of change in the duty ratio (change in the amount of engagement pressure correction) in the previous shift is sequentially reflected in the next correction of the initial value of the engagement pressure. Regardless of how the oil pressure is supplied, a good engagement pressure setting is performed from the beginning. FIG. 10 is a control flow obtained by rewriting the control flow of FIG. 9 to a more specific level. This control flow is
The construction is such that substantially the same operation as that of FIG. 9 can be obtained by using six PHASEs. It will be easy to understand how the flow chart of FIG. 9 is embodied by looking at the contents described in each step. Therefore, only the steps similar to those in FIG. A duplicate description will be omitted. Means for determining the next initial date ratio from changes in the duty ratio during feedback control of the engagement pressure include:
Other embodiments as shown in FIGS. 11A and 11B are also conceivable. First, the change in the duty ratio is monitored from the start of the feedback control of the engagement pressure, and the value Dp of the duty ratio at the time when the peak of the change in the duty ratio first appears and the time Tp thereof are stored. On the other hand, the previous initial duty ratio is Ds, and the inertia phase start recognition time is Ts. From these four values, the change rate of the duty ratio after the start of the feedback and the change rate until the change direction of the duty ratio changes are obtained. The next initial duty ratio Dsn is determined according to the result. In this case, the initial duty ratio Dsn is obtained as Dsn = Ds + (Dp−Ds) / Tp−Ts × α.
In addition, as shown in FIGS. 11 (A) and (B), (Dp−D
s) / (Tp-Ts) indicates the average slope of the duty ratio after the feedback control is started until the direction in which the duty ratio changes is changed. With such a correction, if the initial duty ratio setting is too high and the correction to reduce the duty ratio starts at the same time as the feedback control starts, the next initial duty ratio Dsn is set to a lower value, and moreover, after the feedback control starts, The sooner the correction, the sooner the initial duty ratio
Since the correction of Dsn becomes large, the previous history can be favorably reflected.

【The invention's effect】

As described above, according to the present invention, the engagement pressure of the time from the hydraulic pressure supply command to the start of the change in the rotation speed of the rotary member (the time until the inertia phase starts) also varies among the individual vehicles. And the like can be set to an appropriate value in consideration of the above-mentioned factors, and an excellent effect that the shift control can be performed more smoothly is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the gist of the present invention, FIG. 2 is a schematic block diagram of an automatic transmission for a vehicle to which an embodiment of the present invention is applied, and FIG. FIG. 4 is a diagram showing an operation state of the friction engagement device in the automatic transmission, FIG. 4 is a hydraulic circuit diagram showing a main part of a hydraulic control device of the automatic transmission, and FIG. 5 is a diagram showing good feedback control. FIG. 6 is a diagram showing shift characteristics when the initial engagement pressure is too low, and FIGS. 7A and 7B are diagrams showing the next time from the history of the duty ratio. FIG. 8 is a diagram for explaining a method for determining an initial duty ratio of the vehicle, FIG. 8 is a diagram showing shift characteristics when the initial engagement pressure is too low and the shift cannot be completed in the buffer region of the accumulator; FIG. 9 is a diagram showing a control flow in the above-mentioned embodiment apparatus, and FIG. More specifically rewrite line diagram of the control flow of Fig. 9, FIG. 11 is a duty ratio diagram showing another example for obtaining the next initial duty ratio from the history of the duty ratio. 108: Accumulator control valve, 112: Accumulator, S _D: Linear solenoid, PS ₁ ... Solenoid pressure, NT: Turbine speed, NT _0: Turbine target speed, Dn: Previous shift Initial duty ratio of, Dsn ... Initial duty ratio of previous shift.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (3)

(57) [Claims] 1. A shift control device for an automatic transmission configured to maintain good shift characteristics by performing feedback control of an engagement pressure of a friction engagement device during a shift, wherein the shift control device is adapted to control the running parameters of the vehicle. Means for determining an initial value at the time of starting the feedback control of the engagement pressure; and
Means for detecting the time until the inertia phase starts, and means for correcting the initial value of the current engagement pressure based on the time until the inertia phase starts, Transmission control device for transmission. 2. A system according to claim 2, further comprising means for presetting a predetermined threshold value with respect to the time until the inertia phase starts, wherein the learning based on the time until the inertia phase starts is performed. A shift control device for an automatic transmission, wherein the shift control is performed based on a comparison between a threshold value and a time until an actual inertia phase starts. 3. A shift control device for an automatic transmission configured to maintain good shift characteristics by controlling an engagement pressure of a friction engagement device at the time of shifting, wherein the shift control device controls the engagement of the automatic transmission according to running parameters of a vehicle. Means for determining an initial value when starting the control of the combined pressure; means for detecting the time until the inertia phase starts in the control of the engagement pressure at the time of the previous shift; and until the inertia phase starts. A means for correcting the initial value of the current engagement pressure based on the time of (c).