JP2018132142A - Control device for stepped automatic transmission - Google Patents

Abstract

In a control device for a stepped automatic transmission that performs a shift based on a target shift characteristic, an increase in shift time is suppressed even when a multiple shift is performed after a target shift characteristic update setting.
A control device for a stepped automatic transmission that performs a shift by controlling hydraulic pressures of a plurality of friction engagement elements based on a target shift characteristic. Characteristic updating means (ST2, ST3) for updating and setting the target shift characteristics at the start of shifting and at the time of switching from upshift to downshift or downshift to upshift, and characteristics for maintaining the updated target shift characteristics Holding means (ST6) and execution means (ST4) for executing the shift after the update setting based on the target shift characteristics after the shift progress at the time of the update setting. The characteristic updating means is configured to update and set the target shift characteristic even when the shift progress is decreased by a predetermined value or more after the target shift characteristic is updated and set (ST5, ST3).
[Selection] Figure 5

Description

  The present invention relates to a control device for a stepped automatic transmission, and more particularly to a control device for a stepped automatic transmission that executes a shift based on a target shift characteristic.

  Conventionally, in a stepped automatic transmission that forms a transmission gear stage by switching a plurality of friction engagement elements, hydraulic control of the friction engagement elements is performed so that the actual transmission characteristic matches the target transmission characteristic. ing. Specifically, the target speed change characteristic is usually the input shaft speed according to the degree of speed change ((input shaft speed-synchronous speed before shifting) / (synchronous speed after shifting-synchronous speed before shifting)). Thus, the hydraulic control of the friction engagement element is performed so that the actual gradient of the input shaft rotational speed matches the target gradient. In such a target shift characteristic, a relatively small target gradient Δ1 is considered in the initial stage of the shift (when the shift progress is small) in consideration of the hydraulic response delay, and relative to the middle of the shift (when the shift progress is medium). In general, a relatively large target gradient Δ2 is set to a relatively small target gradient Δ3 at the end of the shift (when the shift progress is large) in order to suppress the blow-up.

  By the way, the target speed change characteristic is set to decrease the input shaft rotational speed in the upshift, and is set to increase the input shaft rotational speed in the downshift. When the coefficient of friction is small, there is a problem that the release timing of the release side frictional engagement element is too early compared to the engagement timing of the engagement side frictional engagement element during downshifting, and blowing up occurs.

  Therefore, for example, Patent Document 1 discloses an automatic gear shift that eliminates the blow-up state at the next shift by correcting the target shift time to be longer when a blow-up of the input shaft rotation speed is detected during a downshift. A machine control device is disclosed.

JP 11-210874 A

By the way, in the shift control based on the target shift characteristics as described above, when a multiple shift to be switched from an upshift to a downshift or from a downshift to an upshift is performed at the beginning of the shift, it takes time to complete the shift. There is a problem that it becomes longer than that. In the following description, for convenience, n-speed (n is a positive integer) → n + 1-speed upshift and n + 1-speed → n-speed downshift, and there is no change in the vehicle speed during the shift, and upshift suppose the synchronized rotation speed after shifting omega _AD at pre-shift synchronizing speed omega _BU and the down shift is the same.

For example, at the start of upshifting, after the transmission input shaft rotational speed decreases with a relatively small target gradient _ΔU1 from the pre-shift synchronous rotational speed ωBU, with a relatively large target gradient ΔU2 in the middle of the shift. A target shift characteristic that decreases is set. Then, the shift middle of upshift, in other words, when the switching instead new target shift characteristic is set to downshift when the input shaft rotational speed has decreased to some extent from the pre-shift synchronizing speed omega _BU, the input shaft Since there is a difference between the rotational speed and the post-shift synchronous rotational speed ω _AD and it hits the middle of the shift in the downshift, the shift after the update setting is started with a relatively large target gradient ΔD2. Therefore, in subsequent downshifts, the input shaft rotational speed increases with a relatively large target gradient ΔD2 in the middle of the shift, and then increases with a relatively small target gradient ΔD3 at the end of the shift while synchronizing after the shift. Since the hydraulic pressure control is performed so as to reach the rotational speed ω _AD , there is no problem that the time required to complete the shift becomes longer than necessary.

In contrast, the upshift early, in other words, when the switching instead new target shift characteristic is set to downshift when the input shaft rotation speed is not reduced almost from the synchronization pre-shift rotation speed omega _BU, the input shaft Since the difference between the rotational speed and the post-shift synchronous rotational speed ω _AD is small and hits the end of the shift in the downshift, the shift after the update setting is started with a relatively small target gradient ΔD3 toward the completion of engagement. become.

  In addition, even when switching from upshift to downshift, the shift may proceed in the upshift direction (the shift progress in the downshift decreases) due to the hydraulic response delay of the friction engagement element. Even if such shift reduction occurs, when switching to downshift at the beginning of upshifting, only a relatively small target gradient ΔD3 is buffered (stored), so the input shaft rotational speed is There is a problem that it does not rise easily and the time required to complete the shift becomes longer than necessary.

  In particular, as in the case of the above-mentioned Patent Document 1, when the increase in the input shaft rotation speed is detected at the time of downshifting, the multiple shift that switches to the downshift at the initial stage of the upshift is performed when the target shift time is corrected. If it is executed, there is a risk that the shift time will be longer. The above problems can also occur when switching to an upshift at the beginning of a downshift.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a multi-stage automatic transmission control device that executes a shift based on a target shift characteristic, after the setting of the target shift characteristic is set. It is an object of the present invention to provide a technique for suppressing an increase in the time required to complete a shift even when a shift is performed.

  In order to achieve the above object, the control device for a stepped automatic transmission according to the present invention not only updates and sets the target shift characteristic when multiple shifts are performed, but also shifts after setting the target shift characteristic. The target shift characteristic is updated and set so as to match the actual input shaft rotational speed even when it is largely reversed.

  Specifically, the present invention executes a shift by controlling the hydraulic pressures of a plurality of friction engagement elements forming a shift gear stage based on a target shift characteristic including a target gradient of a transmission input shaft rotation speed. The target is a control device for a stepped automatic transmission.

  The control device includes a characteristic update unit that updates and sets a target shift characteristic based on a vehicle state at the start of a shift and when switching from an upshift to a downshift or from a downshift to an upshift, and the characteristic update unit A characteristic holding unit that holds the target shift characteristic that is updated by setting, and a target shift characteristic that is updated by the characteristic update unit, based on a target shift characteristic after the shift progress at the time of update setting, after the update setting And the characteristic updating means is configured to update and set the target shift characteristic even when the shift progress is reduced by a predetermined value or more after the target shift characteristic is updated and set. It is characterized by being.

  In the following, for convenience of explanation, it is assumed that n-speed → n + 1-speed upshift and n + 1-speed → n-speed downshift and that there is no change in vehicle speed during shifting, the present invention The case is not limited.

  According to this configuration, the target shift characteristic is updated and set when switching from upshift to downshift or from downshift to upshift. Therefore, even when multiple shifts are performed after the start of shifts, the target shift characteristics depend on the shift mode after switching. Shifting can be executed.

  For example, when the shift is changed to the downshift after the middle stage of the shift in the upshift (for example, the shift progress of 0.5), the update is set to the target shift characteristic in the downshift, and the shift progress at the time of the update setting (0.5) A downshift is executed based on the subsequent target shift characteristics. As a result, for example, after the input shaft rotation speed increases with a relatively large target gradient in the middle of the shift, a downshift is performed so as to reach the synchronous rotation speed after the shift while increasing with a relatively small target gradient at the end of the shift. Since this is performed, it is possible to prevent the time required to complete the shift from becoming longer than necessary.

  On the other hand, for example, when the shift is changed to the downshift at the initial stage of the upshift (for example, the shift progress degree 0.1), the update is set to the target shift characteristic in the downshift, and after the shift progress degree (0.9) at the update setting Downshift is executed based on the target shift characteristics. Thus, in general, a relatively small target gradient is set at the end of the shift in order to suppress the blow-up, and the downshift is executed based on the target shift characteristic after the shift progress degree 0.9 or later. In this case, the hydraulic control of the frictional engagement element is performed based on a relatively small target gradient.

  Here, even when switching from upshift to downshift, the shift may proceed in the upshift direction due to a delay in the hydraulic response of the friction engagement element (the shift progress may decrease), but the shift progress may decrease. Even if the target gradient is small and relatively small, if the time required to complete the shift does not become longer than necessary, the updated target shift characteristic is maintained.

  On the other hand, if the shift progress is greatly reduced and the target shift characteristic is updated and set, and the shift progress is decreased by a predetermined value or more (for example, the shift progress is reduced to 0.5), the target shift characteristic is updated and set. In addition, the downshift is executed based on the target shift characteristics after the shift progress degree (0.5) at the update setting. As a result, a relatively large target gradient commensurate with the decreased input shaft rotation speed is buffered, so that the input shaft rotation speed decreased due to the hydraulic response delay can be increased with a relatively large target gradient.

  As described above, according to the present invention, it is possible to suppress an unnecessarily long time required to complete a shift regardless of the stage at which the multiple shift is performed.

  In addition, in the present invention, even when multiple shifts are performed in one shift, the target shift characteristic is updated and set when the shift progress degree decreases by a predetermined value or more after the target shift characteristic is updated and set. The time required to complete the shift can be optimized.

  As described above, according to the control device for the stepped automatic transmission according to the present invention, the multiple shift that switches from upshift to downshift or from downshift to upshift is performed after the update setting of the target shift characteristic is performed. Even in this case, it is possible to suppress an increase in the time required to complete the shift.

1 is a schematic configuration diagram schematically showing a vehicle on which an automatic transmission according to the present invention is mounted. 1 is a skeleton diagram schematically showing configurations of a torque converter and an automatic transmission. It is an engagement table | surface which shows the engagement state or release state of the friction engagement element for every transmission gear stage in an automatic transmission. It is a block diagram which shows the structure of the control system of a vehicle. It is a flowchart which shows an example of the target shift characteristic update control which ECU performs. It is a timing chart which shows an example of target shift characteristic update control. FIG. 6 is a diagram schematically illustrating a target shift characteristic and a target shift characteristic at the time of multiple shifts.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram schematically showing a vehicle 10 on which an automatic transmission 3 according to this embodiment is mounted. As shown in FIG. 1, the vehicle 10 includes an engine 1, a torque converter 2, an automatic transmission 3, a hydraulic control device 4, and an ECU 5. The vehicle 10 is, for example, an FF (front engine / front drive) system, and the output of the engine 1 is transmitted to the differential device 6 via the torque converter 2 and the automatic transmission 3, and left and right drive wheels (front wheels) 7. To be distributed.

-Engine-
The engine 1 is a driving power source for traveling, for example, a multi-cylinder gasoline engine. The engine 1 is configured to be able to control an operation state by a throttle opening (intake air amount) of a throttle valve (not shown), a fuel injection amount, an ignition timing, and the like.

-Torque converter-
FIG. 2 is a skeleton diagram schematically showing configurations of the torque converter 2 and the automatic transmission 3. In FIG. 2, the lower half is omitted and only the upper half is shown with respect to the rotation center axes of the torque converter 2 and the automatic transmission 3. As shown in FIG. 2, the torque converter 2 includes a pump impeller 21 connected to a crankshaft 1a that is an output shaft of the engine 1, a turbine runner 22 connected to the automatic transmission 3, and a stator having a torque amplification function. 23, and a lockup clutch 24 for directly connecting the engine 1 and the automatic transmission 3.

-Automatic transmission-
The automatic transmission 3 is provided in a power transmission path between the engine 1 and the drive wheel 7 and forms a plurality of transmission gear stages to shift the rotation of the input shaft 3a and output it to the output shaft 3b. It is configured as a stepped automatic transmission. In the automatic transmission 3, the input shaft 3 a is connected to the turbine runner 22 of the torque converter 2, and the output shaft 3 b is connected to the drive wheels 7 through the differential device 6 and the like.

  The automatic transmission 3 includes a first transmission unit 31 mainly composed of a first planetary gear unit 31a, and a second transmission unit 32 mainly composed of a second planetary gear unit 32a and a third planetary gear unit 32b. The first clutch C1 to the fourth clutch C4, the first brake B1, the second brake B2, and the like.

  The first planetary gear device 31a constituting the first transmission unit 31 is a double pinion type planetary gear mechanism, and supports a sun gear S1, a plurality of pairs of pinion gears P1 meshing with each other, and the pinion gears P1 so as to be able to rotate and revolve. Planetary carrier CA1 and ring gear R1 meshing with sun gear S1 via pinion gear P1.

  The planetary carrier CA1 is connected to the input shaft 3a and rotates integrally with the input shaft 3a. The sun gear S1 is fixed to the transmission case 30 so as not to rotate. The ring gear R1 functions as an intermediate output member, is decelerated with respect to the input shaft 3a, and transmits the decelerated rotation to the second transmission unit 32.

  The second planetary gear unit 32a constituting the second transmission unit 32 is a single pinion type planetary gear mechanism, which is a sun gear S2, a pinion gear P2, and a planetary carrier RCA that supports the pinion gear P2 so as to be capable of rotating and revolving. And a ring gear RR that meshes with the sun gear S2 via the pinion gear P2.

  The third planetary gear device 32b constituting the second transmission unit 32 is a double pinion type planetary gear mechanism, which is a sun gear S3, a plurality of pairs of pinion gears P2 and pinion gears P3 that mesh with each other, and the pinion gears P2 and pinion gears. A planetary carrier RCA that supports P3 so as to rotate and revolve, and a ring gear RR that meshes with the sun gear S3 via the pinion gear P2 and the pinion gear P3. The pinion gear P2, the planetary carrier RCA, and the ring gear RR are shared by the second planetary gear device 32a and the third planetary gear device 32b.

  The sun gear S2 is selectively connected to the transmission case 30 by the first brake B1. The sun gear S2 is selectively connected to the ring gear R1 via the third clutch C3. Further, the sun gear S2 is selectively coupled to the planetary carrier CA1 via the fourth clutch C4. Sun gear S3 is selectively coupled to ring gear R1 via first clutch C1. The planetary carrier RCA is selectively coupled to the transmission case 30 by the second brake B2. Further, the planetary carrier RCA is selectively coupled to the input shaft 3a via the second clutch C2. The ring gear RR is connected to the output shaft 3b and rotates integrally with the output shaft 3b.

  The first clutch C1 to the fourth clutch C4, the first brake B1, and the second brake B2 are all friction engagement elements that are frictionally engaged by a hydraulic actuator, and are controlled by the hydraulic control device 4 and the ECU 5.

  FIG. 3 is an engagement table showing an engaged state or a released state of the first clutch C1 to the fourth clutch C4, the first brake B1, and the second brake B2 for each transmission gear stage. In the engagement table of FIG. 3, a circle indicates an “engaged state”, and a blank indicates a “released state”.

  As shown in FIG. 3, in the automatic transmission 3 of this example, the first clutch C1 and the second brake B2 are engaged, so that the gear ratio (the rotational speed of the input shaft 3a / the rotational speed of the output shaft 3b). The first transmission gear stage (1st) having the largest value is established. The second transmission gear stage (2nd) is established by engaging the first clutch C1 and the first brake B1.

  The third transmission gear stage (3rd) is established by engaging the first clutch C1 and the third clutch C3, and the fourth transmission gear stage (3rd) is established by engaging the first clutch C1 and the fourth clutch C4. 4th) is established.

  The fifth transmission gear stage (5th) is established by engaging the first clutch C1 and the second clutch C2, and the sixth transmission gear stage (5th) is established by engaging the second clutch C2 and the fourth clutch C4. 6th) is established.

  The seventh transmission gear stage (7th) is established by engaging the second clutch C2 and the third clutch C3, and the eighth transmission gear stage (7th) is established by engaging the second clutch C2 and the first brake B1. 8th) is established. The reverse speed (Rev) is established when the third clutch C3 and the second brake B2 are engaged.

-Hydraulic control device-
The hydraulic control device 4 controls the engagement and disengagement of the plurality of friction engagement elements (the first to fourth clutches C1 to C4 and the first and second brakes B1 and B2) of the automatic transmission 3. The hydraulic control device 4 also has a function of controlling the lockup clutch 24 of the torque converter 2. The hydraulic control device 4 includes a hydraulic actuator (not shown) for each friction engagement element of the automatic transmission 3 and a linear solenoid valve (not shown) for supplying control hydraulic pressure to each hydraulic actuator. I have.

-ECU-
The ECU (control device) 5 is configured to perform operation control of the engine 1, shift control of the automatic transmission 3, and the like. Specifically, as shown in FIG. 4, the ECU 5 includes a CPU 51, a ROM 52, a RAM 53, a backup RAM 54, an input interface 55, and an output interface 56.

  The CPU 51 executes arithmetic processing based on various control programs and maps stored in the ROM 52. The ROM 52 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The RAM 53 is a memory that temporarily stores a calculation result by the CPU 51, a detection result of each sensor, and the like. The backup RAM 54 is a nonvolatile memory that stores data and the like to be saved when the ignition is turned off.

  A crank position sensor 81, an input shaft rotational speed sensor 82, an output shaft rotational speed sensor 83, an accelerator opening sensor 84, a throttle opening sensor 85, an air flow meter 86, and the like are connected to the input interface 55.

  The crank position sensor 81 is provided for calculating the rotational speed of the engine 1. The input shaft rotational speed sensor 82 is provided for calculating the rotational speed ωi (= turbine rotational speed ωt) of the input shaft 3 a of the automatic transmission 3. The output shaft rotational speed sensor 83 is provided for calculating the rotational speed ωo of the output shaft 3 b of the automatic transmission 3. The vehicle speed v can be calculated from the rotational speed ωo of the output shaft 3b. The accelerator opening sensor 84 is provided to detect an accelerator opening that is a depression amount (operation amount) of an accelerator pedal (not shown). The throttle opening sensor 85 is provided for detecting the throttle opening of the throttle valve. The air flow meter 86 is provided for detecting the intake air amount of the engine 1.

  To the output interface 56, an injector 91, an igniter 92, a throttle motor 93, the hydraulic control device 4 and the like are connected. The injector 91 is a fuel injection valve and can adjust the fuel injection amount. The igniter 92 is provided for adjusting the ignition timing by a spark plug (not shown). The throttle motor 93 is provided to adjust the throttle opening of the throttle valve.

  The ECU 5 is configured to be able to control the operating state of the engine 1 by controlling the throttle opening, the fuel injection amount, the ignition timing, and the like based on the detection results of each sensor. Further, the ECU 5 is configured to be able to execute shift control of the automatic transmission 3 and control of the lock-up clutch 24 of the torque converter 2 by controlling the hydraulic control device 4.

  In the shift control by the ECU 5, for example, the target shift gear stage is set based on a shift map using the vehicle speed v and the accelerator opening as parameters. Note that the shift map is a map in which a plurality of regions for obtaining an appropriate shift gear stage (the shift gear stages 1st to 8th with the optimum efficiency) are set according to the vehicle speed v and the accelerator opening. It is stored in the ROM 52 of the ECU 5. In the shift map, a plurality of shift lines for dividing each region (upshift lines and downshift lines for partitioning each shift region from 1st to 8th) are set.

  Then, the ECU 5 controls the first to fourth clutches C1 via the hydraulic control device 4 based on the target shift characteristics including the target gradient of the input shaft rotational speed ωi so that the current shift gear stage becomes the target shift gear stage. Shift is executed by controlling the hydraulic pressures of .about.C4 and the first and second brakes B1, B2. The ECU 5 is configured to optimize the time required to complete the shift by performing a target shift characteristic update control, which will be described later, when performing a shift based on such a target shift characteristic.

-Shift control using a shift model-
Before describing the target shift characteristic update control, an outline of shift control for determining a control operation amount in the automatic transmission 3 so as to make the actual shift characteristic coincide with the target shift characteristic will be described.

  As a general shift control, for example, whether or not a shift shock, a shift time, and the like are appropriate in an actual vehicle while evaluating whether or not each friction engagement element at the time of a shift is based on a control map predetermined by adaptation. There is a method of determining a torque capacity (or hydraulic pressure command value) and executing a shift. In the method using the control map, it is necessary to create a large number of control maps in accordance with a combination of a shift pattern such as a power-on downshift or a power-off upshift and a shift gear stage before and after the shift. For this reason, the greater the number of shift gears of the stepped automatic transmission, the more labor is required for the adaptation work.

  Therefore, in the present embodiment, as a shift control, instead of using a control map, a shift execution method using a shift model that determines a control operation amount that matches the actual shift characteristic with the target shift characteristic is used. Adopted. The target shift characteristic is a target value of an element (for example, a shift time, a rotation speed gradient, a driving force, etc.) that determines a change mode to be realized at the time of shifting. The control operation amount is a required value of an element (engine torque, clutch torque, etc.) operated with respect to the control target.

  Hereinafter, the shift control using the shift model will be described. The equation of motion during the shift is expressed by the following equations (1) and (2).

  These expressions (1) and (2) are derived from the equations of motion of the mutually connected rotating elements constituting the automatic transmission 3 and the relational expression in the planetary gear device constituting the automatic transmission 3. Is. The equation of motion of each rotating element is the torque represented by the product of the inertia in each rotating element and the rate of change of rotational speed with time. The rotation of each of the three members of the planetary gear device and the members on both sides of the friction engagement element The equation of motion is defined by the torque acting on the member involved in the element. Further, the relational expression in the planetary gear unit is a relational expression that defines the relationship between the torque and the rate of change in the rotational speed time in the three members of the planetary gear unit using the gear ratio of the planetary gear unit.

  In the formulas (1) and (2), dωt / dt is a time derivative of the turbine rotational speed ωt (that is, the input shaft rotational speed ωi of the automatic transmission 3), that is, a time change rate, and is a rotating member on the input shaft 3a side. Represents the acceleration (angular acceleration, hereinafter referred to as input axis acceleration) of the input shaft 3a as a speed change amount. This input shaft acceleration dωt / dt corresponds to the gradient of the input shaft rotation speed ωi in the present invention. dωo / dt is a time change rate of the output shaft rotation speed ωo of the automatic transmission 3 and represents the output shaft acceleration. Tt represents turbine torque that is torque on the input shaft 3a as torque on the rotating member on the input shaft 3a side, that is, transmission input torque Ti. The turbine torque Tt agrees with the engine torque Te (= Tt / t) when the torque ratio t of the torque converter 2 is taken into consideration. To represents transmission output torque that is torque on the output shaft 3b as torque on the rotating member on the output shaft 3b side. Tcapl is a torque capacity (hereinafter referred to as an engagement-side clutch torque) of a friction engagement element that performs an engagement operation at the time of shifting. Tcdrn is the torque capacity of the friction engagement element that performs the releasing operation at the time of shifting (hereinafter referred to as the release side clutch torque). a1, a2, b1, b2, c1, c2, d1, and d2 are constants when the expressions (1) and (2) are derived, respectively, and the inertia and planetary gear unit gears in each rotating element It is a coefficient determined by design from the ratio. The specific numerical value of this constant varies depending on, for example, the type of shift (for example, a shift pattern or a combination of shift gears before and after the shift). Therefore, the above equation of motion is one predetermined equation, but the equation of motion corresponding to each type of shift, which is a constant different for each type of shift, is used for the shift of the automatic transmission 3.

  Expressions (1) and (2) are gear train motion equations of the automatic transmission 3 in which the relationship between the target shift characteristic and the control operation amount is formulated. The target speed change characteristic can express each target value of speed change time and driving force and can be handled on the gear train motion equation. In the present embodiment, the input shaft acceleration dωt / dt is used as an example of a physical quantity that can express the shift time. The transmission output torque To is used as an example of a physical quantity that can express the driving force. Here, in the present embodiment, the target shift characteristic is the target value (target gradient) of the input shaft acceleration dωt / dt. Note that the target shift characteristic may be a target value of the shift time (target shift time) or the like.

  On the other hand, in the present embodiment, the control operation amount of the control (feedback control) that establishes the target shift characteristic includes the turbine torque Tt (the engine torque Te is also agreed), the engagement side clutch torque Tcapl, and the release side clutch torque Tcdrn. The three values are set. Then, since the equation of motion is composed of the two formulas (1) and (2), since there are three control manipulated variables, the control manipulated variable that establishes the two target shift characteristics is uniquely solved. It is not possible. The output shaft acceleration dωo / dt in each equation is calculated from the output shaft rotation speed ωo that is a detection value of the output shaft rotation speed sensor 83.

  Therefore, in the present embodiment, the torque sharing ratio of the transmission torque that is handled by the disengagement side clutch and the engagement side clutch is used as a constraint condition for obtaining the solution of the equations of motion of Expression (1) and Expression (2). By using the torque sharing ratio as a constraint, torque transfer between the disengagement side clutch and the engagement side clutch (that is, shift progress) during gear shifting can be incorporated into the equation of motion, and the control operation amount can be solved uniquely. be able to.

  The torque sharing ratio is the total transmission torque (total transmission torque) that must be handled by the disengagement side clutch and the engagement side clutch when shifting the automatic transmission 3, for example, torque on the input shaft 3a (total transmission on the input shaft). Torque) is the ratio of the transmission torque shared by both friction engagement elements to the total transmission torque on the input shaft. Then, such a torque sharing rate is changed according to the shift progress during the shift.

  In this embodiment, the torque sharing rate of the engagement side clutch is set to “xapl”, the torque sharing rate of the release side clutch is set to “xdrn”, and each torque sharing rate reflects the transfer of torque during shifting. Using the torque sharing ratio x (for example, 0 ≦ x ≦ 1) that changes in time series, the following equations (3) and (4) are defined.

xapl = x (3)
xdrn = 1-x (4)
The relational expression between the engagement-side clutch torque Tcapl and the disengagement-side clutch torque Tcdrn is based on “Tcapl” and “Tcdrn” replaced with the torque on the input shaft 3a, and expressions (3) and (4). , “X” (= xapl) and “1-x” (= xdrn). From the expressions (1), (2), and the relational expression between “Tcapl” and “Tcdrn”, the turbine torque Tt, the engagement side clutch torque Tcapl, and the release side clutch torque, which are control operation amounts, are obtained. A relational expression for calculating Tcdrn is derived. The turbine torque Tt (the engine torque Te is also agreed) is a relational expression using “x” (= xapl), “1-x” (= xdrn), input shaft acceleration dωt / dt, transmission output torque To, and the like. It is represented by Similarly, the engagement side clutch torque Tcapl is expressed by a relational expression using “x” (= xapl), the input shaft acceleration dωt / dt, the transmission output torque To, and the like. Similarly, the release side clutch torque Tcdrn is represented by a relational expression using “1-x” (= xdrn), input shaft acceleration dωt / dt, transmission output torque To, and the like.

  In other words, the speed change model of the present embodiment includes the equation of motion (expressions (1) and (2)) of the automatic transmission 3 including the target speed change characteristic and the control operation amount, and the relationship (expression (3)) representing the torque sharing rate. , (4)) is used to calculate the control operation amount based on the target shift characteristic. As described above, in this embodiment, the shift of the automatic transmission 3 is executed using the shift model by adding the constraint condition set by the torque sharing ratio x to the equations (1) and (2). Therefore, even if there are three control operation amounts for the two target shift characteristics, the three control operation amounts can be appropriately determined using the shift model. This shift model is one predetermined model, but as described above, a gear train motion equation having different constants is used for each type of shift (for example, a shift pattern or a combination of shift gears before and after the shift). For the shift of the automatic transmission 3, a shift model corresponding to each shift type is used.

  Then, the ECU 5 calculates a target shift characteristic and a control operation amount in accordance with the shift progress degree for each shift pattern. Note that the shift pattern is, for example, a power-on upshift, a poweroff upshift, a poweron downshift, and a poweroff downshift.

  For example, in the case of a power-on upshift, when the hydraulic control for the friction engagement element according to the target transmission gear stage is started, first, a torque phase stage in which the share of the required torque capacity in each friction engagement element changes, and then After the inertia phase where the gear ratio of the automatic transmission 3 changes, the shift is completed. That is, the shift of the automatic transmission 3 proceeds to the stage before the torque phase, the stage of the torque layer, the stage of the inertia phase, and the stage at the end of the shift.

  A map or the like in which a suitable torque sharing ratio that changes in accordance with the progress of such a shift is set in accordance with the shift progress for each shift pattern is created in advance by experiments or simulations, and is stored in the ROM 52 of the ECU 5. It is remembered. The ECU 5 reads the torque sharing rate according to the degree of shift progress during the shift control, applies the torque sharing rate to the shift model together with the target shift characteristics, and controls the control operation amount (required input torque of the input shaft 3a, engagement Required torque capacity of the friction engagement elements on the side and release side).

  Then, the ECU 5 performs control (hydraulic control) of the engagement side and release side frictional engagement elements in accordance with the degree of shift progress so as to obtain the required torque capacity. Further, the ECU 5 performs shift control so that the actual input shaft rotational speed ωi becomes the target input shaft rotational speed in accordance with the shift progress degree based on the target shift characteristic.

-Target shift characteristic update control-
Next, target shift characteristic update control executed by the ECU 5 will be described.

  As described above, the ECU 5 forms the first to fourth shift gears based on the target shift characteristics including the target gradient (= input shaft acceleration dωt / dt) corresponding to the shift progress of the input shaft rotational speed ωi. Shifting is performed by performing hydraulic control of the clutches C1 to C4 and the first and second brakes B1 and B2. The “shift progress degree” is (input shaft rotation speed−synchronous rotation speed before shift) / (synchronous rotation speed after shift−synchronous rotation speed before shift).

  Specifically, the ECU 5 is configured to update and set the target shift characteristic based on the vehicle state at the start of shift. More specifically, when the target shift gear stage is set based on the shift map, the ECU 5 sets, for example, the transmission input torque Ti and the vehicle speed v (calculated from the output signal of the output shaft rotation speed sensor 83) at the start of the shift. Based on the shift characteristic map stored in the ROM 52, the target shift characteristic is updated and set. The shift characteristic map uses the transmission input torque Ti indicating the vehicle state and the vehicle speed v as parameters, and the target gradient and the target shift time of the input shaft rotational speed ωi required according to the transmission input torque Ti and the vehicle speed v. It is a map set beforehand by experiment or simulation.

  In addition, the ECU 5 performs the shift from the upshift when the multiple shift that switches from the upshift to the downshift or from the downshift to the upshift is performed when the shift is being executed based on the updated target shift characteristic. At the time of switching from downshift or downshift to upshift, the target speed change characteristic is updated and set based on the vehicle state. Specifically, when the target shift gear stage is changed, the ECU 5 refers to the shift characteristic map based on the transmission input torque Ti and the vehicle speed v at the time of switching from upshift to downshift or downshift to upshift. To update the target shift characteristics.

  In principle, the ECU 5 is configured to maintain the updated target shift characteristics except when starting a shift and when switching from an upshift to a downshift or from a downshift to an upshift.

  FIG. 7A is a diagram schematically illustrating an example of target shift characteristics in downshifting. The target shift characteristic updated and set by the ECU 5 includes a target gradient of the input shaft rotational speed ωi corresponding to the shift progress degree. In such a target shift characteristic, a relatively small target gradient Δ1 is considered in the initial stage of the shift (when the shift progress is small) in consideration of the hydraulic response delay, and relative to the middle of the shift (when the shift progress is medium). Therefore, a relatively small target gradient Δ3 is set at the end of the shift (when the shift progress is large) so that a relatively small target gradient Δ3 is set.

  Then, the ECU 5 executes the shift after the update setting based on the target shift characteristic after the shift progress at the time of the update setting among the target shift characteristics that have been updated and set.

FIG. 7B is a diagram schematically illustrating an example of multiple shifts that are switched to the downshift after the middle of the upshift. In the following description, for the sake of convenience, there is no change in the vehicle speed v during the shift from n-th speed (n is a positive integer) → n + 1-speed upshift and n + 1-speed → n-speed downshift. It is assumed that the rotational speed ω _BU and the post-shift synchronous rotational speed ω _AD in the downshift are the same. Such an assumption is merely for convenience of explanation, and is not limited to this. For example, the present invention can also be applied to a case where there is a change in the jump speed or the vehicle speed v during the speed change.

As shown in FIG. 7B, at the start of upshifting, a target shift that decreases from the pre-shift synchronous rotation speed _{ωBU with a} small target gradient ΔU1 and then decreases with a large target gradient ΔU2 in the middle of the shift. The characteristic is updated (see the broken line in FIG. 7B). Thereafter, when the shift to the downshift is made to the middle of the shift in the upshift or the like (for example, shift progress degree 0.5), the ECU 5 changes the target shift characteristic indicated by the broken line in FIG. 7B to the one-dot chain line in FIG. Is updated to the target shift characteristic indicated by. Then, the ECU 5 sets the target shift characteristics (FIG. 7 (b)) after the shift progress degree (0.5) at the time of the update setting, among the updated target shift characteristics (the chain line in FIG. 7 (b)). On the basis of the thick one-dot chain line). Therefore, in the subsequent downshift input shaft speed ωi is, after rising in the shift middle with a large target slope △ D2, elevated while the synchronized rotation speed after shifting omega _AD in the shift late small target slope △ D3 Thus, hydraulic control is performed.

  On the other hand, if multiple shifts are performed, such as switching to downshift at the beginning of the upshift or switching to upshift at the beginning of the downshift, the time required to complete the shift may be longer than necessary. is there. FIG. 7C is a diagram schematically illustrating an example of a multiple shift that switches to a downshift at the beginning of the upshift.

  As shown in FIG. 7C, when the downshift is switched to the initial stage of the upshift (for example, shift progress 0.1), the ECU 5 sets the target shift characteristic indicated by the broken line in FIG. c) Update to the target speed change characteristic indicated by the one-dot chain line. Then, the ECU 5 sets the target shift characteristics (FIG. 7 (c)) after the shift progress (0.9) at the time of the update setting, among the updated target shift characteristics (one-dot chain line in FIG. 7 (c)). On the basis of the thick one-dot chain line). For this reason, the shift after the update setting is started with a relatively small target gradient ΔD3 toward the completion of engagement.

  In addition, even when switching from upshift to downshift, the shift may proceed in the upshift direction (the shift progress in the downshift decreases) due to the hydraulic response delay of the friction engagement element. Even if such shift reduction occurs, when switching to downshift at the beginning of the upshift, only a small target gradient ΔD3 is buffered (stored), so the input shaft rotational speed ωi increases easily. In some cases, the time required to complete the shift becomes longer than necessary.

  Therefore, in the present embodiment, not only the target shift characteristic is updated and set at the start of shift or when multiple shifts are performed, but also when the shift greatly reverses, so as to match the actual input shaft rotational speed ωi. The target shift characteristic is updated and set.

  Specifically, the ECU 5 is configured to update and set the target shift characteristic even when the shift progress degree has decreased by a predetermined value R or more after the target shift characteristic is updated and set. In this case as well, the ECU 5 executes the shift after the update setting based on the target shift characteristics after the shift progress at the time of the update setting, among the target shift characteristics that have been updated and set.

  As described above, when the shift progress is decreased by a predetermined value R or more after the target shift characteristic is updated and set (for example, when the shift progress is decreased to 0.5), the target shift characteristic is updated and set. Since the downshift is executed based on the target shift characteristic after the shift progress degree (0.5) at the time of update setting, a relatively large target gradient (for example, FIG. 7) commensurate with the reduced input shaft rotational speed ωi. ΔD2) is buffered. Therefore, the input shaft rotational speed ωi, which has been reduced due to the hydraulic response delay, can be increased with a relatively large target gradient, thereby suppressing an unnecessarily long time required to complete the shift.

  In addition, even when multiple shifts are performed multiple times in one shift, the ECU 5 updates and sets the target shift characteristic when the shift progress degree decreases by a predetermined value R or more after the target shift characteristic is updated and set. The time required for completion can be optimized.

-Flow chart and timing chart-
Next, an example of target shift characteristic update control executed by the ECU 5 will be described with reference to a flowchart shown in FIG. 5 and a timing chart shown in FIG. Note that the flowchart shown in FIG. 5 is repeated at predetermined time intervals.

<In the case of time t _{0 in} FIG. 6A>
In step ST1 in the flowchart, the ECU 5 determines whether or not the shift control is being performed. At time t ₀ in FIG. 6 (a), since the gear shift has not yet started, the determination in step ST1 is NO and RETURN is performed as it is.

<In the case of time t _{1 in} FIG. 6A>
In step ST1, ECU 5 is, determines whether the shift control in so time t ₁ in FIG. 6 (a) of during the gear shift, the determination in step ST1 proceeds to YES, step ST2.

In the next step ST2, the ECU 5 determines whether or not it is time to start shifting, when switching from an upshift to a downshift, or when switching from a downshift to an upshift. For example, the ECU 5 determines that the shift start time is the time when the target shift gear is set based on the shift map using the vehicle speed v and the accelerator opening as parameters. Since time t _{1 in} FIG. 6 (a) is at the start of shifting, the determination in step ST2 is YES, and the process proceeds to step ST3.

  In the next step ST3, the ECU 5 updates and sets the target shift characteristic with reference to the shift characteristic map based on, for example, the transmission input torque Ti and the vehicle speed v at the start of the shift. Specifically, the upshift target shift characteristic as shown by the broken line in FIG. 6B is updated and set, and the process proceeds to step ST4.

In the next step ST4, the ECU 5 starts the shift after the update setting based on the target shift characteristic after the shift progress at the update setting. Since time t ₁ in FIG. 6A is the start of shifting and the shift progress is 0.0, the ECU 5 applies the target shifting characteristics as indicated by the broken line in FIG. 6B as it is. To start shifting, and then RETURN. As a result, the target gradient ΔU1 at the initial stage of the upshift is buffered, and the ECU 5 starts hydraulic control of the friction engagement element using the shift model based on the target gradient ΔU1.

<In the case of time t ₂ of Fig. 6 (a)>
Time t ₂ in FIG. 6 (a), because during the shift control, the determination in step ST1 proceeds YES, to step ST2. In the next step ST2, the ECU 5 determines whether or not to start shifting, when switching from upshift to downshift, or when switching from downshift to upshift, as shown in FIG. time t ₂ is the upshift early, because none of the time shift start time and multiple shift initiation, the determination in step ST2, the process proceeds nO, to step ST5.

In the next step ST5, the ECU 5 determines whether or not the shift progress has decreased by a predetermined value R or more after the target shift characteristic is updated and set. At time t ₂ of FIG. 6 (a), based on the target slope △ U1, the input shaft rotational speed ωi are decreased gradually, since the shift is in progress as shown in FIG. 6 (b), the step ST5 The determination at is NO, and the process proceeds to step ST6.

  In the next step ST6, the ECU 5 maintains the target speed change characteristic and then performs RETURN. As a result, the target shift characteristic as indicated by the broken line in FIG. 6B, which is updated and set at the start of the shift, is maintained, so that the ECU 5 uses the shift model based on the target gradient ΔU1 to generate the friction engagement element. Continue hydraulic control.

<In the case of time t _{3 in} FIG. 6A>
Time t ₃ in FIG. 6 (a), because during the shift control, the determination in step ST1 proceeds YES, to step ST2. In the next step ST2, the ECU 5 determines whether or not it is time to start shifting, when switching from an upshift to a downshift, or when switching from a downshift to an upshift. Time t ₃ in FIG. 6 (a), exactly because when switching from up-shift to down-shift, the determination in step ST2 goes to YES, and step ST3.

  In the next step ST3, the ECU 5 updates and sets the target shift characteristic with reference to the shift characteristic map based on, for example, the transmission input torque Ti and the vehicle speed v at the time of switching. Specifically, a target shift characteristic for downshift as shown by a broken line in FIG. 6C is set, and the process proceeds to step ST4.

In the next step ST4, the ECU 5 starts the shift after the update setting based on the target shift characteristic after the shift progress at the update setting. At time t ₃ in FIG. 6 (a), since the shift progress degree is 0.9 when seen as a downshift, ECU 5, of the target gear characteristics shown by the broken line in FIG. 6 (c), the time update setting Based on the target shift characteristics after the shift progress degree of 0.9 or later (thick broken line in FIG. 6C), the shift after the update setting is started, and then RETURN is performed. As a result, the relatively small target gradient ΔD ₁₃ at the end of the downshift is buffered, so that the ECU 5 starts hydraulic control of the friction engagement element using the above-described shift model based on the target gradient ΔD _13. To do.

<In the case of time t _{4 in} FIG. 6A>
Time t ₄ in FIG. 6 (a), because during the shift control, the determination in step ST1 proceeds YES, to step ST2. The time t ₄ in FIG. 6 (a), since none of the time shift start time and multiple shift initiation, the determination in step ST2, the process proceeds NO, to step ST5.

In the next step ST5, the ECU 5 determines whether or not the shift progress has decreased by a predetermined value R or more after the target shift characteristic is updated and set. 6 at time t ₄ of (a), but shifted by a hydraulic pressure response delay in the upshift direction of the frictional engagement elements is in progress, yet reduced shift progress degree is a predetermined value R (e.g., 0.4) or more Therefore, the determination in step ST5 is NO, and the process proceeds to step ST6. In the next step ST6, the ECU 5 holds the target shift characteristic indicated by the thick broken line in FIG. 6C, and then performs RETURN.

<In the case of time t _{5 in} FIG. 6A>
Time t ₅ in FIG. 6 (a), because during the shift control, the determination in step ST1 proceeds YES, to step ST2. The time t ₅ in FIG. 6 (a), since none of the time shift start time and multiple shift initiation, the determination in step ST2, the process proceeds NO, to step ST5.

In the next step ST5, the ECU 5 determines whether or not the shift progress has decreased by a predetermined value R or more after the target shift characteristic is updated and set. At time t ₅ in FIG. 6 (a), the fact and that only a relatively small target slope △ D ₁ 3 not buffered for transmission to upshift direction is still in progress by the hydraulic response delay of the frictional engagement elements In combination, the shift progress is reduced by a predetermined value R (0.4) to 0.5, so that the determination in step ST5 is YES and the process proceeds to step ST3.

  In the next step ST3, the ECU 5 updates and sets the target shift characteristic with reference to the shift characteristic map based on the transmission input torque Ti and the vehicle speed v when the shift progress is reduced by a predetermined value R. Specifically, a target shift characteristic for downshift as shown by a broken line in FIG. 6D is set, and the process proceeds to step ST4.

In the next step ST4, the ECU 5 starts the shift after the update setting based on the target shift characteristic after the shift progress at the update setting. At time t ₅ in FIG. 6 (a), since the shift progress degree is 0.5, ECU 5, of the target gear characteristics shown by the broken line in FIG. 6 (d), the shift progress degree 0 when updating settings. Based on the target shift characteristics after 5 (thick broken line in FIG. 6D), the shift after the update setting is started, and then RETURN is performed. Thus, since a relatively large target slope △ D ₂ 2 shift the middle in the down-shift is buffered, ECU 5, using the above-described transmission model based on the target slope △ D ₂ 2, hydraulic control of the friction engagement elements To start.

<In the case of time t ₆ of Figure 6 (a)>
Time t ₆ in FIG. 6 (a), because during the shift control, the determination in step ST1 proceeds YES, to step ST2. The time t ₆ in FIG. 6 (a), since none of the time shift start time and multiple shift initiation, the determination in step ST2, the process proceeds NO, to step ST5.

In the next step ST5, the ECU 5 determines whether or not the shift progress has decreased by a predetermined value R or more after the target shift characteristic is updated and set. At time t ₆ in FIG. 6 (a), the shifting by the hydraulic response delay to the upshift direction of the frictional engagement element to converge, since the shift is in progress as shown in FIG. 6 (d), in step ST5 The determination is NO, and the process proceeds to step ST6. In the next step ST6, the ECU 5 maintains the target speed change characteristic and then performs RETURN. Thus, the input shaft rotational speed ωi is, after rising at a relatively large target slope △ D ₂ 2 in the transmission middle, the synchronized rotation speed omega _AD while rising at a relatively small target slope △ D ₂ 3 in the transmission late Thus, the hydraulic control of the frictional engagement element is performed.

  It should be noted that in relation to the claims, the processing of step ST2 and step ST3 executed by the ECU 5 is “the vehicle state at the start of shifting and at the time of switching from upshift to downshift or downshift to upshift”. This corresponds to “characteristic updating means for updating and setting the target shift characteristic”. The process of step ST6 corresponds to “characteristic holding means for holding the updated target shift characteristic” in the claims. Further, the process of step ST4 corresponds to “execution means for executing the shift after the update setting based on the target shift characteristic after the shift progress at the time of the update setting among the updated target shift characteristics” in the claims. To do. Further, the processing of step ST5 and step ST3 is a characteristic that “the target shift characteristic is updated and set even when the shift progress degree has decreased by a predetermined value or more after the target shift characteristic is updated and set. It corresponds to “update means”.

  As described above, according to the present embodiment, even when a multiple shift is performed after the start of a shift, the target shift characteristic is updated and set based on the vehicle state. Therefore, a shift according to the shift mode after switching is performed. Can be executed.

  Further, even when the shift progress is reduced by a predetermined value R or more after the target shift characteristic is updated, the target shift characteristic is updated and set based on the target shift characteristic after the shift progress at the time of the update setting. Since a downshift is performed, a relatively large target gradient commensurate with the reduced input shaft rotational speed ωi is buffered, so that the input shaft rotational speed ωi decreased due to the hydraulic response delay is reduced to a relatively large target gradient. Can be raised. Accordingly, it is possible to suppress an unnecessarily long time required to complete the shift regardless of which stage the multiple shift is performed.

(Other embodiments)
The present invention is not limited to the embodiments, and can be implemented in various other forms without departing from the spirit or main features thereof.

  In the above embodiment, the present invention is applied in the case of multiple shift switching from upshift to downshift. However, the present invention is not limited to this, and the present invention may be applied to multiple shift switching from downshift to upshift. Good.

  In the above embodiment, the case where the multiple shift is performed only once in one shift has been described. However, the present invention is not limited to this, and multiple shifts may be performed in one shift. The time required to complete the shift can be optimized.

  Further, in the above embodiment, the present invention is applied to the control of the automatic transmission 3 of the forward 8 speed. However, the present invention is not limited to this, and the present invention is applied to the control of the automatic transmission of the forward 7 speed or less or the forward 9 speed or more. May be.

  Moreover, in the said embodiment, although this invention was applied to FF vehicle 10, it is not restricted to this, You may apply this invention to FR (front engine * rear drive) vehicle.

  Furthermore, in the said embodiment, although this invention was applied to the vehicle 10 carrying the multi-cylinder gasoline engine 1, you may apply this invention not only to this but the vehicle carrying a diesel engine etc.

  As described above, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  According to the present invention, even when a multiple shift is performed in which the shift from upshift to downshift or downshift to upshift is performed after the target shift characteristic is updated, the time required to complete the shift is unnecessarily long. Therefore, the present invention is extremely useful when applied to a control device for a stepped automatic transmission that executes a shift based on a target shift characteristic.

3 Automatic transmission 5 ECU (control device)
B1 First brake (friction engagement element)
B2 Second brake (friction engagement element)
C1 first clutch (friction engagement element)
C2 Second clutch (friction engagement element)
C3 3rd clutch (friction engagement element)
C4 4th clutch (friction engagement element)

Claims (1)

A control device for a stepped automatic transmission that executes a shift by controlling the hydraulic pressure of a plurality of friction engagement elements forming a shift gear stage based on a target shift characteristic including a target gradient of a transmission input shaft rotation speed Because
Characteristic updating means for updating and setting the target shift characteristic based on the vehicle state at the start of shifting and at the time of switching from upshift to downshift or downshift to upshift;
Characteristic holding means for holding the target shift characteristic updated by the characteristic update means;
Execution means for executing a shift after update setting based on a target shift characteristic after the shift progress at the time of update setting among the target shift characteristics updated by the characteristic update means,
The characteristic updating means is configured to update and set the target shift characteristic even when the shift progress is decreased by a predetermined value or more after the target shift characteristic is updated and set. Transmission control device.

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