JP3623077B2 - Shifting control device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift transient control device that performs feedback control at the time of shifting a hydraulic pressure supplied to a friction engagement element of a speed change mechanism in an automatic transmission, and includes the feedback control and torque reduction control of an engine at the time of shifting. The present invention relates to a shift transient control device for an automatic transmission that can contribute to further improvement of the shift feeling.
[0002]
[Prior art]
In general, as an automatic transmission for a vehicle, one in which rotation of an engine is input via a torque converter and is shifted by a transmission mechanism having a plurality of planetary gears and output to a propeller shaft (axle side) has become widespread. Yes.
In this type of automatic transmission, the transmission mechanism transmits the rotation of the input shaft from the torque converter to a specific gear or carrier constituting the planetary gear according to the shift position, or rotates the specific gear or carrier. Usually, a plurality of hydraulic friction engagement elements such as clutches and brakes are provided to appropriately transmit to the output shaft or to restrain rotation of a specific gear or carrier as appropriate.
[0003]
Then, by controlling a solenoid valve or the like incorporated in the hydraulic control circuit, the friction engagement element is fastened or released, and a shift is performed. In this case, when the friction engagement element is switched from release to fastening or from fastening to release, there is a problem that an excessive torque shock occurs if the change in the fastening force does not proceed appropriately.
For example, in the upshift, the stage after the point when the load on the disengagement friction engagement element decreases to zero and the first gear shift stage (so-called torque phase) ends and the effective gear ratio starts to change (so-called inertia phase). Then, it is necessary to moderately increase the engagement capacity (that is, supply hydraulic pressure) of the engagement side frictional engagement element and decrease the input shaft rotation speed of the transmission mechanism at an appropriate rate of change.
[0004]
This is because if the engagement capacity is too large at this time, the input shaft rotational speed will rapidly decrease and the shift time required for the shift up will be shortened, but the output shaft torque will temporarily increase and a large shift shock will occur. Occur. On the other hand, if the fastening capacity is too small, the shift time becomes excessive, resulting in a crisp shift feeling.
[0005]
Therefore, conventionally, as disclosed in, for example, Japanese Patent Laid-Open No. 3-37470, the hydraulic pressure (engagement pressure) at the time of gear shift supplied to the friction engagement element is feedback-controlled, and the input shaft rotation speed of the gear shift mechanism is set. There is a control method that changes with a predetermined change characteristic.
In addition, as described in the above publication, learning control is also known in which the initial value of the engagement pressure at the next shift is corrected based on the control result of the feedback control (change amount change mode). Yes.
[0006]
[Problems to be solved by the invention]
By the way, in the above-described conventional control method, the hydraulic pressure at the time of shifting can be held near the optimum value, and so-called shelf deviation (deviation from the hydraulic pressure at ideal shifting) is reduced. Conventionally, however, since the hydraulic pressure at the time of shifting, which is adjusted every time in real time by the feedback control described above and the initial value is corrected, is not necessarily harmonized with the input torque from the engine at the time of shifting, further shifting speed There was a problem in terms of improving the ring.
[0007]
That is, due to variations in engine performance, transmission hydraulic pressure adjustment circuit, etc., for example, the input torque from the engine at the time of shifting is larger than the engagement capacity of the frictional engagement element on the engagement side adjusted by the feedback control or learning control described above. When it is large, the frictional engagement element is slipped every time. Therefore, as shown in FIG. 4, the measured value Nt ₁ of the input shaft rotational speed Nt temporarily exceeds the target value Nt _0, and the end point of the torque phase (that is, the start point of the inertia phase) is the target point T. ₀ shifted to the point in time _{T 1} from. Along with this, the output shaft torque Tp of the transmission shifts from the target waveform Tp ₀ to Tp _1, and so-called torque pull-in (temporary decrease in torque) in the torque phase increases in the time axis direction and shifts. There was a problem of feeling bad.
[0008]
In order to suppress a shift shock, it has been conventionally performed to uniformly reduce the engine torque during a shift. Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 61-119432 and Japanese Patent Application Laid-Open No. 61-119434, according to a deviation from a reference value of a parameter (speed change time, engine speed, etc.) at the time of a shift, It is also known to change the amount of torque reduction at the next shift.
However, it has not been conventionally performed to control the engine torque to a more appropriate value with respect to the control result of the feedback control as described above.
[0009]
Therefore, the present invention achieves harmony between feedback control of the engagement pressure of the friction engagement element at the time of shifting and torque reduction control of the engine at the time of shifting, and the shift transient of the automatic transmission that can further improve the shifting feeling. The object is to provide a control device.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a shift transient control device for an automatic transmission according to claim 1 has a speed change mechanism that changes gears by switching between engagement and release of a plurality of friction engagement elements, and the engagement of the friction engagement elements. A shift transient control device for an automatic transmission equipped with a hydraulic pressure control element for controlling the combined pressure,
Feedback control means for feedback-controlling the engagement pressure via the hydraulic pressure control element so that the actual input shaft rotation speed of the speed change mechanism during a shift is matched with a target rotation speed corresponding to a throttle opening and an engine load;
Torque-down means for reducing engine torque during shifting by a set torque-down amount;
Torque down amount setting means for setting the torque down amount at the current shift based on an integrated value of the correction amount of the engagement pressure in the feedback control at the previous shift ,
The torque down amount setting means functions only when the integrated value of the correction amount at the previous shift is positive and sets the torque down amount at the current shift,
When the integrated value of the correction amount at the previous shift is negative, an engagement pressure initial value changing means for changing the initial value of the engagement pressure at the current shift so as to cancel the integrated value of the correction amount. , Further provided.
[0012]
The shift transient control device for an automatic transmission according to claim 2 , wherein the torque down amount setting means sets the torque down amount separately for each type of shift.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the shift transient control device of this example includes a turbine rotation speed measuring means 1, a transmission control unit 2, a duty solenoid valve 3, and an engine control unit 4. .
[0014]
Here, the turbine rotation speed measuring means 1 is a sensor that detects the input shaft rotation speed Nt of the transmission mechanism 11 in the automatic transmission 10 (in this case, the rotation speed of the rotation shaft connected to the turbine runner of the torque converter 12). is there.
[0015]
Next, the control unit 2 constitutes feedback control means, torque down amount setting means, and engagement pressure initial value changing means of the present invention. Specifically, the control unit 2 operates according to a preset program, It consists of a microcomputer provided with a memory for storing set values.
In this case, the control unit 2 feedback-controls the engagement pressure of the frictional engagement element on the engagement side in the inertia phase during the shift by the processing shown in the flowcharts of FIGS. Based on the amount, the engine torque reduction amount at the next shift is determined and the initial value of the engagement pressure is corrected.
[0016]
The duty solenoid valve 3 corresponds to a hydraulic pressure control element of the present invention, and is a pressure adjusting means incorporated in a hydraulic control circuit provided at the lower part of the transmission mechanism casing, and operates according to a hydraulic control signal of the control unit 2. Then, the line pressure that is the output pressure of the oil pump (not shown) is adjusted to adjust the hydraulic pressure (that is, the engagement pressure) supplied to the friction engagement element of the transmission mechanism.
[0017]
The engine control unit 4 is also a control means of the engine 20 composed of a microcomputer, and includes ignition timing control, intake air amount control, fuel supply amount control, intake / exhaust valve opening / closing timing control, and supercharging pressure control. Various types of electronic control of commonly known engines are performed.
In this case, the control unit 4 has a function of reducing the output torque of the engine at the time of shifting according to the torque-down amount set by the processing of the control unit 2 in accordance with the torque-down command from the control unit 2 for transmission. And constitutes the torque-down means of the present invention.
[0018]
Here, the torque reduction is specifically realized by adjusting the ignition timing of the engine 20, the intake air amount, the fuel supply amount, the intake / exhaust valve opening / closing timing, or the supercharging pressure.
Further, in this case, at the time of shifting, the torque reduction is always performed by a predetermined amount, and the torque reduction amount based on the correction amount of the feedback control described later is added to this constant amount. A configuration in which only torque-down of the torque-down amount based on the feedback control correction amount may be performed.
[0019]
Note that the control of the hydraulic pressure of the disengagement side frictional engagement element during the shift or the control of the hydraulic pressure on the engagement side in the torque phase may be performed as usual by the control unit 2, for example. Since it has a feature in the feedback control of the hydraulic pressure on the side and the torque down amount determination process based on the correction amount of this feedback control, the description of the other control processes is omitted.
Further, the configuration and operation of the transmission 10 and the engine 20 are not particularly limited, and the description thereof is omitted.
[0020]
Next, the hydraulic control processing of the engagement side frictional engagement element in the inertia phase during the shift by the control unit 2 will be described with reference to the flowchart of FIG.
The series of processing shown in FIG. 2 is repeatedly executed at regular intervals, for example, during shifting as part of the processing executed by the control unit 2 (subroutine).
First, in step S2, it is determined whether an inertia phase during shifting is detected. If detected, the process proceeds to step S4, and if not detected, the process proceeds to step S14.
In step S14, integrated values ΔP and Sum described later are reset to zero.
[0021]
Here, the inertia phase detection is performed based on the following principle, for example, by detecting the start of the inertia phase, which is the second stage of shifting. That is, at the start of the inertia phase, the speed Nt of the speed change mechanism input shaft detected by the turbine speed measuring means 1 starts to decrease rapidly if it is a shift up. For this reason, it is determined that the inertia phase has started when such a change in the rotational speed is detected.
[0022]
Next, in step S4, and calculates a target change rate dN ₀ of the input shaft speed Nt. This calculation is performed as follows, for example. In other words, the difference (change amount ΔNt) between the actual input shaft speed Nt based on the measured value at that time and the input shaft speed Nt after the shift obtained from the vehicle speed and the gear ratio after the shift is calculated as the throttle opening. A value ΔNt / T divided by the time T until a predetermined shift time set in advance according to the degree, engine load and the like is set as the target change rate dN ₀ .
[0023]
Next, in step S6, the actual change rate dNt of the input shaft speed Nt at that time is calculated from the actual input shaft speed Nt obtained at that time based on the output signal of the turbine speed measuring means 1. Calculate and read.
The calculation of the measured value of the input shaft rotation speed Nt is performed in another process, for example, at a cycle of 10 msec. Based on the difference between the previous value and the current value, the rate of change dNt (per unit time) Change amount).
[0024]
Next, in step S8, the feedback correction amount Cof of the hydraulic pressure is obtained by the proportional integration method from the values of dN ₀ and dNt obtained in steps S4 and S6, and the integrated value ΔP of the correction amount Cof during the inertia phase is obtained. It is done. Specifically, the correction amount Cof and the integrated value ΔP are obtained from preset constants Ki and KP, for example, by the calculations of the following formulas (1) to (4).
[0025]
Sum = Sum + Kix × (dN ₀ −dNt) (1)
Pro = KP × (dN ₀ −dNt) (2)
Cof = Sum + Pro (3)
ΔP = ΔP + Cof (4)
[0026]
Next, in step S10, the required oil pressure PL at the time of shifting is obtained from the input torque Tvo determined from the intake pressure of the engine and the throttle opening and the shift type based on a well-known function.
[0027]
In step S12, the feedback correction amount Cof obtained in step S8, the necessary hydraulic pressure PL obtained in step S10, and a learning value ΔPold, which will be described later in the previous shift of the same type, are added, and the final result is obtained. A control amount PLout of the appropriate hydraulic control is obtained, and a hydraulic control signal corresponding to this value is output to the duty solenoid valve 3.
Although not shown in FIG. 2, at the end of the shift, a process of registering the integrated value ΔP of the correction amount Cof obtained in step S8 for each shift type as the learned value ΔPold is performed. In this case, the learning value ΔPold of the correction amount has a meaning as a correction amount of the present invention or a change mode of the correction amount.
[0028]
Next, the determination process of the engine torque reduction amount by the control unit 2 will be described with reference to the flowchart of FIG. The series of processing shown in FIG. 3 is executed as part of the processing executed by the control unit 2 (subroutine) every time a shift is performed, from the end of the shift to the start of the next shift. .
First, in step S22, the learning value ΔPold of the correction amount obtained and registered by the process shown in FIG. 2 is read.
[0029]
Next, in step S24, it is determined whether or not the correction value learning value ΔPold is a positive value. If it is positive, the process proceeds to step S26, and when the value of ΔPold is 0 or negative, the torque-down amount is not updated. Thus, a series of processing is completed. When the value of ΔPold is 0 or less, the previously set torque reduction amount is maintained as it is. If the value of ΔPold has never been positive and the torque-down amount has never been updated, the predetermined amount set in advance is maintained as the torque-down amount at the time of shifting.
[0030]
Next, in step S26, the type of shift when the correction amount learning value ΔPold read in step S22 is obtained is read.
In step S28, the value of ΔPold read in step S22 or the shift type read in step S26, for example, the following equation (5) is calculated, and ΔPold is converted into engine torque, thereby reducing the torque reduction amount. A correction amount ΔTe is obtained.
[0031]
ΔTe = μ · D · n · A · ΔPold (5)
The above equation (5) is a case where the frictional engagement element on the fastening side is a hydraulically driven multi-plate type, where μ is the friction coefficient of the friction surface of the frictional engagement element, and D is the frictional engagement element. The effective diameter, n is the number of plates of the friction engagement element, and A is the pressure receiving area of the drive piston.
[0032]
Next, in step S30, the value of ΔPold is reset to 0. Thereafter, in step S32, the determined torque-down amount is output and used for torque-down control by the control unit 4 at the next same type of shift.
[0033]
In the control process described above, the engagement pressure of the friction engagement element of the transmission mechanism 11 is changed so that the input shaft rotation speed Nt changes at a predetermined change rate dN ₀ in the inertia phase during the shift by the processes of steps S2 to S12. (So-called line pressure) is feedback controlled.
Then, in each control cycle during the control, the pressure correction value Cof obtained every time in step S8 is accumulated every time in the same manner in step S8, and this accumulated value ΔP is registered for each shift type as ΔPold after the shift is completed. Is done.
[0034]
Next, when the value of ΔPold registered as described above is positive by the processing of steps S22 to S32, the value of ΔPold corresponding to the amount corresponding to the engine torque is converted to the engine torque so as to cancel this correction amount. The torque down amount is increased and corrected and updated.
[0035]
Therefore, when the actual engagement pressure at the time of shifting adjusted by feedback control or the like is insufficient with respect to the actual engine torque at the time of shifting, and the friction engagement element has insufficient capacity, ΔPold This value becomes a positive value corresponding to the degree of the shortage, and the engine torque Te is excessively reduced by the amount corresponding to the shortage at the next time of the same type of shift.
[0036]
Therefore, the problem that occurs when the engine torque as shown in FIG. 4 is relatively high is always corrected in the second and subsequent shifts of the same type, and better transmission characteristics as shown by the dotted line in FIG. Thus, the torque phase time is shortened and the amount of torque drawn in the torque phase is reduced, and an effect that a better shift feeling is obtained is achieved.
[0037]
Further, in the control of this example, when the learning value ΔPold of the correction amount in the feedback control described above is 0 or less, the engagement pressure in the feedback control at the next same type of shift is canceled so that the correction amount is canceled. The initial value of is changed.
That is, in this case, step S30 is not executed by the branching process of step S24, so the value of ΔPold is maintained as it is. Therefore, in this case, in the next feedback control in the same type of shift, the initial hydraulic pressure at the start of the feedback control becomes PL + Cof + ΔPold by the process of step S12 (PLout = PL + Cof + ΔPold), and the result of the previous shift is the initial hydraulic pressure. It is reflected in.
[0038]
For this reason, the malfunction when engagement pressure is too high with respect to engine torque is eliminated. This is because if the engagement pressure is too high with respect to the engine torque, the speed change characteristic is the reverse of that shown in FIG. 4 and the torque phase time is excessively shortened and the overall speed change ends. The amplitude of the output shaft torque fluctuation in the torque phase becomes excessively large, resulting in a large shift shock. However, in this example, when such a malfunction occurs due to some factor, the value of ΔPold becomes a negative value corresponding to the degree thereof. Therefore, in the same type of gear shift from the next time, the processing in step S12 described above is performed. Thus, the initial hydraulic pressure is reduced by that amount, and the above problem is solved.
[0039]
In this example, the value of ΔPold becomes a positive value, and when the engine torque reduction amount is updated based on this value, the value of ΔPold is reset to 0 in the process of step S30. Therefore, in this case, in the next feedback control in the same type of shift, in the process of step S12, ΔPold = 0, that is, PLout = PL + Cof, and the initial hydraulic pressure at the start of the feedback control becomes PL + Cof, The result of shifting is not reflected.
[0040]
In other words, in this example, when the engagement pressure is insufficient as a result of the feedback control, the engine torque is reduced by the corresponding amount at the next shift, and when the engagement pressure is excessive, the feedback control is performed by the corresponding amount at the next shift. The initial value of the engagement pressure is reduced. For this reason, in a steady state, harmony between the engine torque and the engagement pressure at the time of shifting is maintained, and a more optimal shifting characteristic is always realized.
[0041]
When the engagement pressure is excessive, the engine torque down amount is reduced by that amount, and as a result, the engine torque is increased by that amount, and when the engagement pressure is insufficient, the next shift is performed. A control method for increasing the initial value of the engagement pressure in response thereto may be another aspect of the present invention. However, an increase in the engagement pressure or engine torque at the time of shifting increases the required power. Therefore, in any case as in this example, a mode corresponding to correction in the reduction direction is preferable.
[0042]
In this example, the value of ΔPold is registered for each shift type, and the torque down amount is updated and the initial value of the engagement pressure is changed for each shift type. It is corrected, and further improvement of the shift characteristics can be realized.
[0043]
In addition, this invention is not restricted to the said example of a form, There can be various aspects. For example, in the above-described embodiment, at the time of shifting, the engine torque is basically reduced by a fixed amount, and the torque reduction amount is corrected and updated by the correction amount learned as a result of feedback control. However, there may be a mode in which only a torque reduction based on the correction amount is performed without performing a certain amount of torque reduction.
[0044]
Further, the initial value of the engagement pressure to be changed based on the correction amount of the feedback control may be the engagement pressure at the start of the torque phase instead of the engagement pressure at the start of the inertia phase.
[0045]
Further, the torque reduction amount determination process illustrated in FIG. 3 may be executed by the engine control unit 4. Further, it is needless to say that the engine control unit and the transmission control unit may be integrated into one set, and the transmission and the engine may be controlled by this single unit.
[0046]
【The invention's effect】
In the shift transient control apparatus according to claim 1, the friction engagement of the speed change mechanism is performed by the feedback control means so that the actual input shaft speed of the speed change mechanism during the speed change is matched with the target speed according to the throttle opening and the engine load. The element engagement pressure is feedback controlled.
The torque-down amount setting means sets the torque-down amount of the engine at the current shift based on the integrated value of the correction amount of the engagement pressure in the feedback control at the previous shift. Then, the torque down means reduces the engine torque during the shift by a set torque down amount.
[0047]
Therefore, when the actual engagement pressure at the time of gear shift adjusted by feedback control is insufficient with respect to the actual engine torque at the time of gear shift, and the friction engagement element has insufficient capacity, the correction amount The integrated value becomes a positive value corresponding to the degree of the shortage, and the engine torque is excessively reduced by an amount corresponding to the shortage at the next time of the same type of shift.
[0048]
Therefore, the problem that occurs when the engine torque as shown in FIG. 4 is relatively high is always corrected after the second shift of the same type of shift, and a better shift characteristic as shown by the dotted line in FIG. 4 is obtained. Thus, the torque phase time can be shortened and the amount of torque drawn in the torque phase can be reduced, so that a better shifting feeling can be obtained.
[0049]
Furthermore, in the shift transient control device according to claim 1 , the torque-down amount setting means functions only when the integrated value of the correction amount at the previous shift is positive, and the torque-down amount at the current shift. Set (Increase torque reduction). On the other hand, when the integrated value of the correction amount at the previous shift is negative, the engagement pressure initial value changing means cancels the integrated value of the correction amount so that the initial value of the engagement pressure at the current shift is canceled. To change.
[0050]
For this reason, the effect that the malfunction when the engagement pressure is too high with respect to the engine torque can be solved without increasing the engine torque is also obtained.
This is because if the engagement pressure is too high with respect to the engine torque, the speed change characteristic is the reverse of that shown in FIG. 4 and the torque phase time is excessively shortened and the overall speed change ends. The amplitude of the output shaft torque fluctuation in the torque phase becomes excessively large, resulting in a large shift shock.
[0051]
And in order to suppress such a shift shock, when the engagement pressure is excessive, it is possible to perform a control to decrease the amount of torque reduction of the engine and increase the engine torque accordingly. An increase in engine torque at the time of shifting is not preferable because it increases the required power.
[0052]
However, in the present invention, when such a problem occurs due to some factor, the integrated value of the correction amount becomes a negative value corresponding to the degree. The initial value of the resultant pressure is reduced, and the above problem is solved without increasing the engine torque.
[0053]
In other words, according to the present invention, when the engagement pressure is insufficient as a result of the feedback control, the engine torque is reduced correspondingly at the next shift, and when the engagement pressure is excessive, the feedback control is correspondingly performed at the next shift. The initial value of the engagement pressure is reduced. For this reason, in a steady state, harmony between the engine torque and the engagement pressure at the time of shifting is maintained, and more optimal shifting characteristics are always realized. In addition, the engine torque and the initial value of the engagement pressure are always corrected only in the decreasing direction at the time of shifting, which is advantageous in terms of fuel consumption.
[0054]
In the shift transient control apparatus according to the second aspect , the torque-down amount is set separately for each type of shift. For this reason, the variation unique to the transmission type is also finely corrected, and further improvement of the transmission characteristics can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a shift transient control apparatus which is an example of the present invention.
FIG. 2 is a flowchart showing characteristic control processing contents of the apparatus.
FIG. 3 is a flowchart showing characteristic control processing contents of the apparatus.
FIG. 4 is a diagram for explaining a conventional problem and the operation of the present invention.
[Explanation of symbols]
1 Turbine speed measurement means (speed detection means)
2 Transmission control unit (feedback control means, torque-down amount setting means, and engagement pressure initial value changing means)
3 Duty solenoid valve (hydraulic pressure control element)
4 Engine control unit 10 Transmission 11 Transmission mechanism 12 Torque converter 20 Engine

Claims (2)

A shift transient control device for an automatic transmission having a speed change mechanism for changing speed by switching between engagement and release of a plurality of friction engagement elements, and a hydraulic pressure control element for controlling the engagement pressure of the friction engagement elements.
Feedback control means for performing feedback control of the engagement pressure via the hydraulic pressure control element so that the actual input shaft rotation speed of the speed change mechanism during a shift is matched with a target rotation speed corresponding to a throttle opening and an engine load;
Torque-down means for reducing engine torque during shifting by a set torque-down amount;
Torque down amount setting means for setting the torque down amount at the current shift based on an integrated value of the correction amount of the engagement pressure in the feedback control at the previous shift ,
The torque down amount setting means functions only when the integrated value of the correction amount at the previous shift is positive and sets the torque down amount at the current shift,
When the integrated value of the correction amount at the previous shift is negative, an engagement pressure initial value changing means for changing the initial value of the engagement pressure at the current shift so as to cancel the integrated value of the correction amount. A shift transient control device for an automatic transmission , further comprising: The torque reduction amount setting means for each type of shift, the shift transient control system for an automatic transmission according to claim 1, characterized in that to set the torque reduction amount separately.

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