JP2005042871A - Speed-change controller of continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speed-change controller of a continuously variable transmission which can secure good acceleration even when re-acceleration is performed immediately after down-shifting. <P>SOLUTION: This speed-change controller of the continuously variable transmission includes an engine 1, the continuously variable transmission 2 which can selectively switchably perform an auto mode and a manual mode, a rotation maintaining down-shifting mode commanding means for commanding a rotation maintaining down-shafting mode by a driver down-shifting operation to be distinguished from a normal operation during manual mode selection, and a rotation maintaining down-shifting control means for controlling a speed-change ratio so as to maintain the predetermined engine rotational speed of a high rotational speed range having the sufficient allowance margin of the engine rotational speed to the upper limit of the rotational speed when the rotation maintaining down-shifting mode is commanded. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a shift control device for a continuously variable transmission with a manual mode in which a driver can select a shift stage from a plurality of shift stages.

In the manual mode attached to the continuously variable transmission, the driver can select a gear position from a plurality of gear speeds appropriately provided in the gear shift line (see, for example, Patent Document 1).
JP 2002-243031 A.

  However, when running on a mountain road etc. with a vehicle equipped with a conventional continuously variable transmission with manual mode, after braking before the curve, the driver operates the lever to re-accelerate and downshift There is a scene. At this time, there is a problem that depending on the vehicle speed, there is little room to the upper limit of the engine speed after the downshift, the engine speed reaches the upper limit immediately upon acceleration, and the upshift occurs, resulting in poor acceleration.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a transmission control device for a continuously variable transmission that can ensure good acceleration even if re-acceleration is performed immediately after a downshift. To do.

In order to achieve the above object, in the present invention,
Engine,
A continuously variable transmission capable of selectively switching between auto mode and manual mode;
During the manual mode selection, rotation maintenance downshift mode command means for commanding the rotation maintenance downshift mode by a driver downshift operation distinguished from normal operation;
Rotation maintenance downshift that controls the gear ratio so that the engine speed is maintained at a predetermined engine speed in a high engine speed range with sufficient margin up to the upper limit of the engine speed when there is a command for rotation maintenance downshift mode Control means;
A transmission control device for a continuously variable transmission is provided.

  Therefore, in the transmission control device for a continuously variable transmission according to the present invention, if there is a rotation maintenance downshift mode command during manual mode selection, the rotation maintenance downshift control means sets the engine rotation speed to the rotation speed upper limit. Because the gear ratio is controlled so as to maintain a predetermined engine speed in a high engine speed range with a sufficient margin until the engine speed immediately reaches the upper limit even if re-acceleration is performed immediately after the downshift. And good acceleration can be ensured.

  Hereinafter, the best mode for realizing a transmission control device for a continuously variable transmission according to the present invention will be described based on a first embodiment shown in the drawings.

First, the configuration will be described.
FIG. 1 is an overall system diagram showing a transmission control apparatus for a continuously variable transmission according to a first embodiment. As shown in FIG. 1, the engine drive system includes an engine 1, a continuously variable transmission 2, drive shafts 3 and 4, and tires 5 and 6.

  The continuously variable transmission 2 includes a torque converter (not shown) that inputs driving force from the engine 1, a continuously variable transmission mechanism that shifts input rotation at a continuously variable transmission ratio, and output rotation from the continuously variable transmission mechanism. And a differential mechanism that transmits to the left and right drive shafts 3 and 4 while allowing a differential. Examples of the continuously variable transmission mechanism include a belt type continuously variable transmission mechanism in which a belt is stretched between two pulleys, and a toroidal type continuously variable transmission mechanism in which a power roller is set between input and output disks. Adopted.

  As shown in FIG. 1, the control system of the engine 1 and the continuously variable transmission 2 includes sensors / switches 7, a CVT control unit 8, and an ENG control unit 9.

  The sensors / switches 7 include an engine speed sensor 71 for detecting the engine speed, an accelerator position sensor 72 for detecting the accelerator position, a speed ratio sensor 73 for detecting the speed ratio, and a vehicle speed sensor 74 for detecting the vehicle speed. , A brake switch 75 for detecting a brake operation, a manual mode switch 76 for detecting a manual mode (= a mode for selecting a plurality of fixed gear ratios manually), an up / down switch for issuing an upshift command and a downshift command in the manual mode 77.

  The CVT control unit 8 determines a target gear ratio based on, for example, input information from the sensors / switches 7 and a command from the ENG control unit 9, and outputs a command for obtaining the target gear ratio to a gear ratio actuator (not shown). To do.

  The ENG control unit 9 determines a target throttle opening based on, for example, input information from the sensors / switches 7 and a command from the CVT control unit 8, and sends a command for obtaining the target throttle opening to an electric throttle (not shown). Output to the actuator. Note that the CVT control unit 8 and the ENG control unit 9 are connected by a bidirectional communication line such as a CAN communication line in order to exchange information with each other.

  Next, the operation will be described.

  [Rotation maintenance downshift control processing]

  FIG. 2 is a flowchart showing the flow of the rotation maintaining downshift control process executed by the CVT control unit 8 of the first embodiment. Each step will be described below (rotation maintaining downshift control means).

In step S1, it is determined whether or not all the control conditions are satisfied. If YES, the process proceeds to step S2 to start a rotation maintaining downshift, and if NO, the process proceeds to the end.
Here, the control condition is
(1) The vehicle speed is higher than the set vehicle speed

This “set vehicle speed” refers to a vehicle speed at which a predetermined engine speed cannot be maintained at a vehicle speed below this, and is set according to the vehicle speed at the point where the lowest LOW shift line and the predetermined engine speed intersect, as shown in FIG. The The “predetermined engine speed” is an engine speed control target during the rotation maintaining downshift control. As shown in FIG. 4, the engine speed is equivalent to 60% to 80% of the maximum engine output in the engine output characteristics. Set to engine speed.
(2) Accelerator OFF

“Accelerator OFF” refers to a time when it is determined that the accelerator is released by a signal from the accelerator opening sensor 72, the idle switch, or the like.
(3) Brake ON

“Brake ON” refers to a time when it is determined by a signal from the brake switch 75 that the brake is being operated.
(4) Operate the shift lever to the downshift side twice in succession (rotation maintaining downshift mode command means)

This double downshift determination is performed according to a flowchart shown in FIG.
The above four conditions, and when all these four conditions are satisfied, the rotation maintaining downshift control mode (= maximum output point) for controlling the gear ratio so as to keep the engine speed at a predetermined engine speed regardless of the vehicle speed. Follow mode) starts.

Note that during the rotation maintaining downshift control mode, as shown in FIG.
(1) Operation from manual mode to D range
(2) Shift up or down operation in manual mode
(3) When the vehicle speed falls below the set vehicle speed
(4) If at least one of the conditions when the shift line catches up with the original shift line is satisfied, the rotation maintaining downshift control mode is canceled when the condition is satisfied.

  In step S2, it is determined whether or not the engine speed is equal to or higher than a predetermined engine speed. If YES (engine speed ≥ predetermined engine speed), the process proceeds to step S3, and if NO (engine speed). <Predetermined engine speed) shifts to step S4.

  In step S3, when it is determined in step S2 that the engine speed is equal to or higher than the predetermined engine speed, as shown by the solid line (1) in FIG. And the process proceeds to step S5.

  In step S4, when it is determined in step S2 that the engine speed is less than the predetermined engine speed, the engine speed is increased to the predetermined engine speed as shown by the dotted line (1) in FIG. Then, the process proceeds to step S5.

  In step S5, it is determined whether or not engine speed = predetermined engine speed. If YES, the process proceeds to step S7, and if NO, the process proceeds to step S6.

  In step S6, it is determined whether or not braking is being performed based on the determination that engine speed is not equal to the predetermined engine speed in step S5. If YES, the process returns to step S2, and if NO, step S7 is determined. Migrate to

  In step S7, when the engine speed reaches the predetermined engine speed as determined in step S5, the engine speed is kept at the predetermined engine speed as shown by a solid line and a dotted line (2) in FIG. To do. When the brake is turned ON → OFF in step S6, the engine speed is kept at the value when the brake is turned ON → OFF, and the process proceeds to step S8 (brake release operation corresponding control means).

  In step S8, it is determined whether or not an accelerator depression operation has been performed with the engine speed kept in step S7. If YES, the process proceeds to step S9. If NO, the process returns to step S7.

  In step S9, based on the reacceleration operation determination by stepping on the accelerator in step S8, the fixed gear ratio is determined based on the vehicle speed at that time, and the process proceeds to step S10. That is, as shown by the dotted line characteristic in FIG. 3B, a virtual fixed shift line representing the fixed gear ratio is determined by the vehicle speed (accelerator operation corresponding control means).

  In step S10, the fixed gear ratio determined in step S9 is maintained, and the process proceeds to step S11. That is, as shown by the solid line (1) in FIG. 3 (b), the operating point is shifted along the virtual fixed shift line.

  In step S11, it is determined whether or not the vehicle speed and the engine speed have increased due to reacceleration while maintaining the fixed gear ratio, and the vehicle speed has approached the upshift vehicle speed. If YES, the process proceeds to step S12. In the case of, return to Step S10.

  In step S12, the fixed speed ratio is gradually returned to the original speed ratio, and the process proceeds to step S13. That is, as indicated by a solid line (2) in FIG. 3B, the operating point is gradually shifted from the virtual fixed shift line to the original fixed gear ratio line.

  In step S13, it is determined whether or not the gear ratio is on the original fixed gear ratio line. If YES, the process proceeds to the end, and if NO, the process returns to step S12.

  [Double downshift determination processing]

  FIG. 5C is a flowchart showing the flow of the double downshift determination process included in the control condition in step S1 of FIG. 2, and each step will be described below.

  In step S51, it is determined whether or not a downshift command has been issued by a downshift operation in the manual mode. If YES, the process proceeds to step S62, and if NO, the process proceeds to the end.

  In step S52, a timer is started based on the first downshift command output from step S51. In step S53, it is determined whether the timer is operating. If YES, the process proceeds to step S54, and NO. In this case, the process proceeds to step S56.

  In step S54, it is determined whether or not a second downshift command has been issued during the timer operation. If YES, the process proceeds to step S55, and if NO, the process returns to step S53.

  In step S55, based on the determination that the second downshift command is issued during the operation of the timer in step S54, the double shift down determination is turned ON, and the process proceeds to step S57.

  In step S56, when the timer operation is stopped without the second downshift command being issued in step S53, it is determined that the normal downshift command is issued, and a one-stage downshift is executed, and step S57 is executed. Migrate to

  In step S57, if a double shift down determination is made in step S55, the timer is stopped and reset to proceed to the end, or if it is determined in step S56 that it is a normal downshift command, the timer is reset. To the end.

  Therefore, when the driver operates the shift lever to the downshift side twice continuously with the intention of shifting to the rotation maintaining downshift control mode, the timer is started when the first downshift command is issued. The second downshift command is issued during the operation of step S51. In the flowchart of FIG. 5C, the process proceeds from step S51 to step S52 to step S53 to step S54 to step S55, and in step S55, a double shift is performed. A determination of down is made.

  On the other hand, when the driver operates the shift lever to the downshift side only once for the purpose of downshifting the first stage, the second time during the operation of the timer that starts when the first downshift command is issued. A downshift command is not issued, and in the flowchart of FIG. 5 (c), step S51 → step S52 → step S53 → step S54 to step S53 → step S54 are repeated. Proceeding to step S56, it is determined at step S56 that the command is a normal downshift command.

  [Shifting down in conventional manual mode]

  As shown in FIG. 6, the manual mode attached to the continuously variable transmission is operated by a driver from a plurality of gears (for example, 1st gear to 6th gear) appropriately provided in the shift line. It is possible to select the gear position. That is, the shift control is performed so as to follow the fixed shift line of the shift stage selected by the driver. Then, in order to prevent engine overrev (overspeed), when the vehicle speed reaches the set speed at each gear, the gear is automatically shifted up and a manual shift down is permitted.

  However, the manual mode of the continuously variable transmission has a plurality of fixed shift lines, and when the driver selects a certain shift stage, the shift control is performed so as to follow that shift stage. Although there is a pleasure that the driver can select the gear ratio, there is a problem that the feature of the continuously variable transmission that the continuously variable transmission is possible is not fully utilized.

  Further, in the manual mode, in order to prevent engine overrev, automatic shift up is performed when the vehicle speed set for each shift speed is exceeded, and shift down is permitted when the vehicle speed falls below. Therefore, when the downshift is performed during braking in the manual mode, the engine speed increases as shown by the solid and dotted lines in FIG. 7 (a). In the case of the solid line characteristics in FIG. 7 (b), the engine speed until the automatic shift up is sufficient, but in the case of the dotted line characteristics in FIG. 7 (b), the engine speed until the automatic shift up. There is a problem in that there is no room for the number, and the up-shift occurs immediately and the re-acceleration is not good.

  That is, when driving on a mountain road or the like with a continuously variable transmission equipped with a manual mode, a scene where the driver down-shifts by operating the lever for re-acceleration after braking before the curve is often seen. At this time, when the vehicle speed is high, there is little room until the upper limit of engine rotation after downshifting, the upper limit rotation is reached immediately upon reacceleration, and upshifting occurs, resulting in poor acceleration.

  [Starting operation of rotation maintaining downshift control mode]

In contrast, in the transmission control device for a continuously variable transmission according to the first embodiment,
(1) The vehicle speed is higher than the set vehicle speed
(2) Accelerator OFF
(3) Brake ON
(4) When all the conditions for the double downshifting operation are satisfied, in the flowchart of FIG. 2, the process proceeds from step S1, step S2, step S3 (or step S4), step S5, step S7, and the engine speed is reduced. A rotation maintaining downshift control mode in which the gear ratio is controlled so as to maintain a predetermined engine speed regardless of the vehicle speed is started.

  Therefore, in this rotation maintaining downshift control mode, the engine speed is always kept at a predetermined engine speed by making use of the characteristics of the continuously variable transmission 2 capable of continuously variable speed shifting, so that the engine speed is always high. Sufficient allowance up to the upper limit of engine rotation can be obtained while maintaining several ranges.

  As shown in FIG. 3, the vehicle speed condition that the vehicle speed is equal to or higher than the set vehicle speed is a value corresponding to the intersection of the lowest LOW line (maximum reduction ratio that the continuously variable transmission 2 can take) and the predetermined engine speed. This is because the engine speed cannot be maintained at a predetermined engine speed at a vehicle speed lower than this. It is to be noted that the vehicle speed is controlled so as to follow the lowest gear ratio at vehicle speeds below this.

  It is natural that the accelerator OFF condition and the brake ON condition are based on the downshift command and it is assumed that the accelerator is OFF. However, the brake OFF is added to this for the following reason. If this control is started when the accelerator is off or the brake is off (coating), the gear ratio will shift from HI to LOW while keeping the engine speed. Become. As the gear ratio shifts from HI to LOW, the engine brake becomes stronger and stronger, so the brake ON condition is included in the control start condition so as not to give the driver such a sense of incongruity.

  The double shift down operation condition is that the rotation maintaining downshift control is a control that keeps the engine speed constant for re-acceleration after deceleration, but when the driver is decelerating, for example, before the curve, It cannot be determined whether it is due to a stop. Therefore, by using the shift lever operation by the driver as a control trigger, the driver can intentionally start the rotation maintaining downshift control mode. Further, by performing the double shift down operation, it is possible to realize a clear intention display of the driver who shifts to the rotation maintaining downshift control mode without providing a new switch or the like and with a less troublesome operation method.

  [Re-acceleration during rotation maintaining downshift control mode]

  When the brake is turned ON → OFF with the intention of reacceleration during the rotation maintaining downshift control mode, if the engine speed already matches the predetermined engine speed, step S5 → The process proceeds from step S7 to step S8, and unless the accelerator is turned OFF → ON, the process repeats step S8 and step S7. In step 7, the gear ratio is controlled so that the engine speed maintains the predetermined engine speed. The When the brake is turned ON → OFF and the engine speed does not match the predetermined engine speed, the process proceeds to step S5 → step S6 → step S7 → step S8 in the flowchart of FIG. Unless OFF → ON, step S8 and step S7 are repeated. In step 7, the gear ratio is controlled so that the engine speed maintains a predetermined engine speed.

  That is, when a brake release operation is performed during the rotation maintaining downshift control, the gear ratio is controlled so as to maintain the engine speed at that time. The reason for this is that the brake release operation during the rotation maintaining downshift control is considered to be because the driver depresses the accelerator pedal at the next moment, or the driver depresses the accelerator pedal in the near future. This is because the gear ratio is shifted to the LOW side for the next re-acceleration even if the target engine speed is not reached during running. Incidentally, the gear ratio shifts to the LOW side when the vehicle speed decreases while maintaining the engine speed.

  As described above, when the accelerator is turned OFF → ON after the brake is turned ON → OFF, the flow proceeds to step S8 → step S9 → step S10 → step S11 in the flowchart of FIG. As long as the vehicle speed does not reach near the upshift vehicle speed, the flow from step S10 to step S11 is repeated, and in step S10, the fixed gear ratio determined by the vehicle speed at the time when the accelerator is OFF → ON is maintained.

  Therefore, a linear acceleration feeling can be produced for the driver by setting the gear ratio immediately after the accelerator is depressed to a fixed gear ratio. In addition, since the shift line can be started from any vehicle speed, it is possible to obtain a sense of acceleration with no sense of incongruity and good response.

  Further, the vehicle speed and the engine speed increase due to reacceleration by the accelerator OFF → ON operation, and when the vehicle approaches the automatic shift up vehicle speed, the flow proceeds to step S11 → step S12 → step S13 in the flowchart in FIG. Until the ratio reaches the original speed change line, the flow from step S12 to step S13 is repeated. In step S12, the speed change ratio is set so as to gradually return from the fixed speed ratio determined by the vehicle speed to the original speed ratio. Is controlled.

  Therefore, after the time when the accelerator is turned OFF → ON, the vehicle speed is accelerated along the virtual fixed speed ratio line other than the preset fixed speed ratio line as described above, and then the vehicle speed reaches the automatic upshift vehicle speed. If the gear ratio control that jumps to the preset fixed gear ratio line at a time is performed, the driver feels uncomfortable. On the other hand, when the vehicle approaches the automatic shift up vehicle speed, the gear ratio is controlled so as to gradually return from the fixed gear ratio determined by the vehicle speed to the original gear ratio, resulting in a smooth automatic upshift. An uncomfortable feeling is prevented.

  [Release action of rotation maintenance downshift control mode]

In the first embodiment, during the rotation maintaining downshift control mode,
(1) Operation from manual mode to D range
(2) Shift up or down operation in manual mode
(3) When the vehicle speed falls below the set vehicle speed
(4) If at least one of the conditions when the shift line catches up with the original shift line is satisfied, the rotation maintaining downshift control mode is canceled when the condition is satisfied.

  The release condition by the operation to the D range is that the rotation maintaining downshift control can be easily performed by switching from the manual mode to the D range when the rotation maintaining downshift control is activated by an erroneous operation of the driver. That is, it has a meaning of providing a release condition by driving operation.

  The release condition by the shift-up operation or the shift-down operation in the manual mode has a meaning that the release condition by the driving operation is provided similarly to the release condition by the operation to the D range.

  The release condition of less than the set vehicle speed is limited because the engine speed cannot be maintained at the predetermined engine speed if the vehicle speed falls below the set vehicle speed indicated by the control start condition during deceleration by braking.

  The release condition of catching up with the original shift line is that this rotation maintaining downshift control mode is a control that keeps the engine speed at a predetermined engine speed in preparation for re-acceleration after braking, so this control is effective forever. If this happens, the driver may feel uncomfortable. Therefore, a release condition based on the gear ratio is provided so that the rotation maintaining downshift control can be released naturally after deceleration → re-acceleration.

  [When reaccelerating after braking just before the curve]

  In re-acceleration after braking before a curve in a conventional vehicle with a continuously variable transmission with manual mode, as shown in Fig. 8, if the accelerator is OFF and the brake is ON at time t1 in 3rd speed, Thereafter, the engine speed decreases due to the accelerator OFF operation. Then, at time t3 when the engine speed becomes lower than the predetermined engine speed, when the driver shifts down to the second speed in order to maintain the high engine speed, the gear ratio shifts to the second speed gear ratio at the time t4. The engine speed increases to the maximum engine speed range. After that, when the brake is turned ON → OFF at time t5 and the accelerator is turned OFF → ON for re-acceleration at time t6, the engine speed once decreased increases again at time t7 when the maximum engine speed is reached. Automatic shift up from 2nd to 3rd. And until t8 when it reaches the 3rd speed, the engine speed decreases rapidly, but from the time of t8, the engine speed gradually increases while maintaining the 3rd speed, and reaches the maximum engine speed at the time of t12. Again, the automatic shift up from the third speed to the fourth speed. Therefore, the engine speed after downshifting from the 3rd speed to the 2nd speed has no allowance to the upper limit of the engine speed, and when the accelerator is turned OFF → ON for re-acceleration at the time of t6, the engine speed is immediately at the time of t7. There is a problem that the number reaches the upper limit and the upshift is automatically performed from the second speed to the third speed, and the acceleration performance is not good.

  On the other hand, in Example 1, when re-acceleration after braking before the curve, as shown in FIG. 8, the accelerator is turned off and the brake is turned on at the time of t1 in the third speed, and a double downshift operation is performed. Is performed, the rotation maintaining downshift control mode is entered, and from the time point t1 to the time point t2, control is performed to reduce the engine speed to a predetermined engine speed by following the manual mode shift line. From the time t2 when the engine speed reaches the predetermined engine speed to the time t6, the engine speed is maintained at the predetermined engine speed regardless of the vehicle speed even if the brake is turned off at the time t5. Gear ratio control, that is, control that changes the gear ratio steplessly in the direction of gradually approaching the gear ratio of the second gear from the gear ratio of the third gear, taking advantage of the characteristics of the continuously variable transmission 2 capable of continuously variable gear shifting. Is done. If the driver turns the accelerator off and then on for re-acceleration at t6, the vehicle will accelerate at a fixed gear ratio between the 3rd and 2nd speed determined by the vehicle speed, and the acceleration feeling is linear and responsive. Acceleration feeling is improved by directing. When the vehicle speed approaches the automatic shift-up vehicle speed at time t9, control is performed to gradually return from the intermediate fixed gear ratio to the original three-speed gear ratio, and at time t10, the third gear ratio is reached. When the engine speed reaches the maximum engine speed, the gear shifts automatically from the third speed to the fourth speed at t11.

  Therefore, in the rotation maintaining downshift control mode of the first embodiment, the engine speed becomes a downshift from the third speed with a margin until the upper limit of the engine speed to the intermediate gear ratio, and the accelerator is re-accelerated at time t6. If the engine speed is switched from OFF to ON, the engine speed is on standby at a predetermined engine speed, so that good acceleration performance can be obtained using the high output region of the engine as much as possible. That is, it can be said that the rotation maintaining downshift control is particularly effective in sports running.

Next, the effect will be described.
In the continuously variable transmission control device of the first embodiment, the following effects can be obtained.

  (1) Engine 1, continuously variable transmission 2 capable of selectively switching between auto mode and manual mode, and rotation maintaining downshift by driver downshift operation distinguished from normal operation during manual mode selection When there is a rotation maintenance downshift mode command means for commanding the mode and a rotation maintenance downshift mode command, the engine rotation speed is set to a predetermined engine rotation speed in a high rotation speed range with a sufficient margin up to the rotation speed upper limit. Since the rotation maintaining downshift control means for controlling the gear ratio so as to maintain is provided, good acceleration can be ensured even if reacceleration is performed immediately after the downshift.

  (2) When the engine speed is higher than the predetermined engine speed, the rotation maintaining downshift control means decreases the engine speed by following the shift line in the manual mode, and the engine speed is lower than the predetermined engine speed. When the engine speed is increased to a predetermined engine speed and the engine speed reaches the predetermined engine speed, the gear ratio is controlled to keep the engine speed constant at the predetermined engine speed. The engine speed can always be maintained in a high speed range, and the high output range of the engine 1 can be easily used in the rotation maintaining downshift control mode.

  (3) The rotation maintaining downshift control means prohibits the rotation maintaining downshift control from being entered when the vehicle speed condition that the vehicle speed is equal to or higher than the set vehicle speed is not satisfied even if the rotation maintaining downshift mode is commanded. If the maintenance downshift control is permitted, the engine speed can be reliably kept at the predetermined engine speed.

(4) The rotation maintaining downshift control means includes:
・ When the vehicle speed is higher than the set vehicle speed ・ When the accelerator is released ・ When the brake is being operated ・ When the rotation maintenance downshift mode command is issued, the rotation maintenance downshift control is performed. In order to start, in the rotation maintaining downshift mode, taking advantage of the continuously variable transmission 2 capable of continuously variable speed shifting, the engine speed is always kept in a high speed range, and the allowance to the upper limit of the engine speed is sufficient. Can be taken.

(5) The rotation maintenance downshift control means, during the rotation maintenance downshift control,
-When switching from manual mode to drive range-When shifting up or down in manual mode-When the vehicle speed falls below the set vehicle speed due to brake operation-The vehicle is accelerated again and the gear ratio is If any one of the above conditions is met when catching up with the shift line, the rotation maintaining downshift control is canceled, so the control release by the driver's operation, the control release by the vehicle speed limit, and the re-acceleration Smooth release of control can be achieved together.

  (6) When the brake operation is released during the rotation maintaining downshift control, the brake release operation corresponding control means for controlling the gear ratio so as to keep the engine speed at that time is provided, so that it is predicted after the brake release operation. The gear ratio can be shifted to the low side in preparation for the accelerator operation for reacceleration.

  (7) When the accelerator is depressed during the rotation maintaining downshift control, the accelerator operation corresponding control means for setting the fixed speed ratio obtained from the vehicle speed at that time is provided, so that a linear acceleration feeling is produced for the driver. In addition, since the fixed gear ratio line can be set up regardless of the vehicle speed, it is possible to obtain a sense of acceleration with no sense of incongruity and good response.

  (8) When the acceleration and vehicle speed increase due to re-acceleration and the automatic shift-up vehicle speed approaches, the accelerator operation corresponding control means gradually returns from the fixed gear ratio determined only by the vehicle speed to the original gear ratio. Therefore, the driver does not feel uncomfortable when returning to the original fixed gear ratio from the acceleration state with a fixed gear ratio other than the preset fixed gear ratio line.

  (9) The rotation maintaining downshift mode command means operates when the driver operates the shift lever to issue a downshift command once within a predetermined time after issuing the downshift command once. Therefore, the driver's clear intention display to shift to the rotation maintaining downshift control can be realized without providing a new switch or the like and with a less troublesome operation method.

  (10) The rotation maintaining downshift control means sets the predetermined engine speed, which is an engine speed control target during the rotation maintaining downshift control, to an engine equivalent to 60% to 80% of the maximum engine output in the engine output characteristics. In order to set the engine speed, the engine is always on standby at an operating point where sufficient engine rotation allowance is secured to maintain the other engine speed range and to allow the engine to stretch during acceleration. It is possible to use the high output area of the engine during re-acceleration.

  As mentioned above, although the transmission control apparatus of the continuously variable transmission of this invention was demonstrated based on Example 1, it is not restricted to this Example 1 about a concrete structure, Each claim of a claim Design changes and additions are permitted without departing from the spirit of the invention.

  For example, in the first embodiment, the example of the double shift down operation is shown as the rotation maintaining downshift mode command means. However, as long as it can be distinguished from the normal one downshift command, the rotation is not limited to the double shift down operation. Other operations may be used. In addition, a dedicated switch for the rotation maintaining downshift mode may be provided and operated.

  The transmission control device for a continuously variable transmission according to the present invention is not limited to a belt type or a toroidal type that has already been put into practical use as a continuously variable transmission, but various types such as a continuously variable transmission using a differential gear. Can be used. Further, any vehicle equipped with a manual mode continuously variable transmission can be applied to vehicles of various types such as passenger cars and SUVs.

1 is an overall system diagram illustrating a transmission control device for a continuously variable transmission according to a first embodiment. It is a flowchart which shows the flow of the rotation maintenance downshift control processing performed by the CVT control unit of Example 1. FIG. 6 is an operation explanatory diagram on a shift map at the time of braking and reacceleration in the speed change control device for the continuously variable transmission according to the first embodiment. FIG. 3 is an engine output characteristic diagram illustrating setting of a predetermined engine speed in the transmission control device for a continuously variable transmission according to the first embodiment. It is a figure which shows the flowchart for the control start conditions in the transmission control apparatus of the continuously variable transmission of Example 1, control release conditions, and a double downshift determination. It is a figure which shows the manual mode shift line of a continuously variable transmission. It is explanatory drawing of the shift down effect | action at the time of braking by the conventional manual mode, and the automatic shift up effect | action at the time of reacceleration. 5 is a comparison time chart showing the time of re-acceleration after braking before a curve in the conventional apparatus and the transmission control apparatus for the continuously variable transmission according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Continuously variable transmission 3, 4 Drive shaft 5, 6 Tire 7 Sensors / switches 71 Engine speed sensor 72 Accelerator opening sensor 73 Gear ratio sensor 74 Vehicle speed sensor 75 Brake switch 76 Manual mode switch 77 Up / down switch 8 CVT control unit 9 ENG control unit

Claims (10)

Engine,
A continuously variable transmission capable of selectively switching between auto mode and manual mode;
During the manual mode selection, rotation maintenance downshift mode command means for commanding the rotation maintenance downshift mode by a driver downshift operation distinguished from normal operation;
Rotation maintenance downshift that controls the gear ratio so that the engine speed is maintained at a predetermined engine speed in a high engine speed range with sufficient margin up to the upper limit of the engine speed when there is a command for rotation maintenance downshift mode Control means;
A transmission control device for a continuously variable transmission, comprising: In the transmission control device for a continuously variable transmission according to claim 1,
The rotation maintaining downshift control means follows the manual mode shift line when the engine speed is higher than a predetermined engine speed, decreases the engine speed, and when the engine speed is lower than the predetermined engine speed, The engine speed is increased to a predetermined engine speed, and when the engine speed reaches the predetermined engine speed, the speed ratio is controlled so as to keep the engine speed constant at the predetermined engine speed. A transmission control device for a continuously variable transmission. In the shift control device for a continuously variable transmission according to claim 1 or 2,
The rotation maintaining downshift control means prohibits entering the rotation maintaining downshift control when the vehicle speed condition that the vehicle speed is equal to or higher than the set vehicle speed is not satisfied even when the rotation maintaining downshift mode command is issued. A shift control device for a step transmission. The transmission control device for a continuously variable transmission according to any one of claims 1 to 3,
The rotation maintaining downshift control means includes
・ When the vehicle speed is higher than the set vehicle speed ・ When the accelerator is released ・ When the brake is being operated ・ When the rotation maintenance downshift mode command is issued, the rotation maintenance downshift control is performed. A transmission control device for a continuously variable transmission, characterized by starting. The transmission control device for a continuously variable transmission according to any one of claims 1 to 4,
The rotation maintenance downshift control means is configured to perform rotation maintenance downshift control.
-When switching from manual mode to drive range-When shifting up or down in manual mode-When the vehicle speed falls below the set vehicle speed due to brake operation-The vehicle is accelerated again and the gear ratio is A speed change control device for a continuously variable transmission, wherein the rotation maintaining downshift control is canceled when any one of the above conditions is satisfied when catching up with a shift line. The transmission control device for a continuously variable transmission according to claim 5,
Brake release operation response control means for controlling the gear ratio so as to maintain the engine speed at that time when the brake operation is released during the rotation maintaining downshift control is provided. Control device. In the shift control device for a continuously variable transmission according to claim 5 or 6,
A speed change control device for a continuously variable transmission, comprising: an accelerator operation corresponding control means for setting a fixed speed ratio obtained from a vehicle speed when an accelerator depression operation is performed during the rotation maintaining downshift control. The transmission control apparatus for a continuously variable transmission according to claim 7,
The accelerator operation corresponding control means increases the vehicle speed and the engine speed by reacceleration, and when approaching the automatic shift up vehicle speed, the gear ratio is gradually returned from the fixed gear ratio determined only by the vehicle speed to the original gear ratio. A transmission control device for a continuously variable transmission, characterized in that The transmission control device for a continuously variable transmission according to any one of claims 1 to 8,
The rotation maintaining downshift mode command means commands the rotation maintaining downshift mode when the driver operates the shift lever to issue a shiftdown command once and then issues another shiftdown command within a predetermined time. A transmission control apparatus for a continuously variable transmission. The transmission control device for a continuously variable transmission according to any one of claims 1 to 9,
The rotation maintaining downshift control means sets a predetermined engine speed, which is an engine speed control target during the rotation maintaining downshift control, to an engine speed corresponding to 60% to 80% of the maximum engine output in the engine output characteristics. A transmission control device for a continuously variable transmission, characterized by being set.

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