JP5259034B2 - Shift control device for continuously variable transmission - Google Patents

Description

  The present invention relates to a transmission control device for a continuously variable transmission, and more particularly, to improve the traveling performance of a vehicle when the vehicle travels on a downhill road.

  As a continuously variable transmission used for a vehicle such as an automobile, there are a belt type and a toroidal type. A belt-type continuously variable transmission has an input-side primary pulley provided on an input shaft, an output-side secondary pulley provided on an output shaft, and a power transmission element such as a belt or a chain spanned between these pulleys. Then, by changing the groove width of each pulley to change the winding diameter of the power transmission element, the transmission ratio can be changed steplessly and the rotation of the input shaft can be transmitted to the output shaft.

  In such a continuously variable transmission, the gear ratio is automatically controlled based on parameters indicating the operating state such as the throttle opening and the vehicle speed or the engine speed. In other words, the target primary pulley rotation speed is set with reference to the basic shift characteristic map based on this parameter, and the gear ratio is set so that the actual primary pulley rotation speed converges to the target primary rotation speed. According to the basic transmission characteristic map, the smaller the throttle opening, the higher the transmission ratio is set. For this reason, when the driver releases the accelerator pedal when traveling downhill, that is, when traveling downhill, the throttle opening becomes small, the gear ratio is set to the high speed side, and the target input speed decreases, so engine braking does not work. Will be controlled in the direction.

  Therefore, when the vehicle is traveling inertially, i.e., inertial with the accelerator pedal released, the gear ratio is downshifted to the low speed side when the vehicle is traveling on a downhill road instead of a flat road, and the engine speed or primary speed The gear ratio is controlled so that the engine brake is applied by correcting so as to increase the engine speed. For example, in the continuously variable transmission disclosed in Japanese Patent Laid-Open No. 8-21500, the characteristic for setting the target deceleration is corrected depending on whether or not the brake operation is performed at the initial stage of inertial traveling, and the target The deceleration is converged to the correction value.

  Further, when traveling on a downhill road, control is performed such that the lower limit value of the target input rotational speed is set larger than that when traveling on a flat road according to an increase in the absolute value of the weight gradient resistance. However, in this case, the acceleration when the accelerator pedal is depressed during inertia traveling on a downhill road is greater than the acceleration when the accelerator pedal is depressed during inertia traveling on a flat road, and the driver feels uncomfortable. Will have. Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-112682, when the accelerator pedal is depressed during inertia traveling on a downhill road, the target input rotational speed is gradually changed at a predetermined change rate. Thus, there has been proposed a technique for preventing a rapid change in the gear ratio.

Problems to be solved by the invention

  In this technology, when the accelerator pedal is depressed during inertia traveling on a downhill road, the primary value corresponding to the minimum value or the vehicle speed in the normal shift control target rotation speed table is set so that the engine brake correction amount has a predetermined change rate. Control is performed so that the rotational speed gradually decreases toward the lower limit rotational speed set by the original table. However, when the engine speed is released again and the engine brake is required, if the engine speed is reduced at a predetermined rate of change until the lower limit engine speed is reached, regardless of the degree of acceleration or the accelerator pedal being depressed, However, there is a problem in that it is necessary to return to the control for applying the engine brake from a rotational speed lower than necessary, and the engine brake cannot be applied immediately. Also, changes in driving force and engine braking force vary depending on the vehicle speed even at the same rotation speed, so if the gear ratio is controlled at a constant rate of change set in the low vehicle speed range, it may be uncomfortable at high vehicle speed ranges. is there.

  An object of the present invention is to improve traveling performance when traveling downhill on an inertial road.

Means for solving the problem

[Means for Solving the Problems]
A transmission control device for a continuously variable transmission according to the present invention is a transmission control device for a continuously variable transmission that changes the rotation of an input-side rotating body in a stepless manner via a power transmission element and transmits it to an output-side rotating body. A vehicle speed detecting means for detecting the traveling speed of the vehicle, a throttle sensor for detecting the opening of the throttle, an inertia traveling detecting means for detecting that the vehicle is traveling on a downhill road, and the inertia traveling detecting means. Lower limit value setting means for setting a target lower limit value for inertial traveling of the input side rotating body when detecting that the vehicle is traveling inertially on a downhill road, and inertia when an accelerator pedal is depressed during inertial traveling running the cancellation, based on the throttle opening and the vehicle speed, the target rotational speed of the lower limit value of the input side rotary member, and the lower limit value limiting means for setting a lower value than during coasting, during the inertia traveling released, the vehicle speed High vehicle speed When and extremely low vehicle speed range when the range is to lower the rotation speed of the change rate upper limit value of the input-side rotating body to increase the rotational speed of the change rate limit value of the input side rotating body than in the low vehicle speed region And a change rate correction means for correcting the difference.

  In the transmission control device for a continuously variable transmission according to the present invention, when acceleration is started by depressing the accelerator or the like under the state of inertia traveling so that the engine brake is applied on a downhill road, The engine can be prevented from overspeeding and mitigating over-acceleration and vibration noise, and excessive rotation fluctuations can be prevented even if the accelerator is opened slightly. Inertia travel control can be performed up to a high vehicle speed range.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a drive system of a belt-type continuously variable transmission as an example of a continuously variable transmission. In this continuously variable transmission, the rotation of a crankshaft 2 driven by an engine 1 It has a drive-side primary shaft 5 that is transmitted via the forward / reverse switching device 4 and a driven-side secondary shaft 6 that is parallel to the drive-side primary shaft 5.

  The primary shaft 5 is provided with a primary pulley 7. This primary pulley 7 slides in the axial direction on the primary shaft 5 by a ball spline or the like so as to be opposed to the fixed pulley 7a integrated with the primary shaft 5. The movable pulley 7b can be freely mounted, and the cone surface interval of the pulley, that is, the pulley groove width is variable. The secondary shaft 6 is provided with a secondary pulley 8. The secondary pulley 8 is fixed to the fixed shaft 8a integrated with the secondary shaft 6. The movable pulley 8b is slidably mounted on the pulley, and the pulley groove width is variable.

  A belt 9 as a power transmission element is stretched between the primary pulley 7 and the secondary pulley 8, and the ratio of the winding diameter of the belt 9 to each pulley is changed by changing the groove width of both pulleys 7 and 8. Is changed, the rotation of the primary shaft 5 is steplessly changed and transmitted to the secondary shaft 6. If the winding diameter of the drive belt 9 around the primary pulley 7 is Rp and the winding diameter around the secondary pulley 8 is Rs, the gear ratio, i.e., the pulley ratio i is i = Rs / Rp.

  The rotation of the secondary shaft 6 is transmitted to the drive wheels 12a and 12b via a gear train having a reduction gear and a differential device 11. In the case of front wheel drive, the drive wheels 12a and 12b are front wheels.

  In order to change the groove width of the primary pulley 7, a plunger 13 is fixed to the primary shaft 5, and a primary cylinder 14 slidably contacting the outer peripheral surface of the plunger 13 is fixed to the movable pulley 7b. 13 and the primary cylinder 14 form a drive oil chamber 15. On the other hand, in order to change the groove width of the secondary pulley 8, a plunger 16 is fixed to the secondary shaft 6, and a secondary cylinder 17 slidably contacting the outer peripheral surface of the plunger 16 is fixed to the movable pulley 8b. The drive oil chamber 18 is formed by the blanker 16 and the secondary cylinder 17. Each groove width is set by adjusting the primary pressure Pp introduced into the primary drive oil chamber 15 and the secondary pressure Ps introduced into the secondary drive oil chamber 18.

  The hydraulic oil in the oil pan 20 is supplied to the drive oil chambers 15 and 18 by an oil pump 21 driven by an engine or an electric motor, and is connected to the discharge port of the oil pump 21. The secondary pressure path 22 thus communicated is connected to the drive oil chamber 18 and to the secondary pressure port of the secondary pressure regulating valve 23. The secondary pressure Ps supplied to the drive oil chamber 18 by the secondary pressure adjusting valve 23 is adjusted to a pressure commensurate with the transmission capacity required for the belt 9.

  The secondary pressure path 22 is connected to the secondary pressure port of the primary pressure adjustment valve 24 via a communication oil path 25, and the primary pressure port of the primary pressure adjustment valve 24 is connected to the primary side drive oil via the primary pressure path 26. It communicates with the chamber 15. The primary pressure adjustment valve 24 adjusts the primary pressure Pp to a value corresponding to the target gear ratio, the vehicle speed, etc., and the groove width of the primary pulley 7 changes to control the gear ratio. The secondary pressure adjusting valve 23 and the primary pressure adjusting valve 24 are proportional solenoid valves, respectively, and the secondary pressure Ps and the primary pressure Pp are controlled by controlling the current values supplied from the transmission control device 30 to the solenoid coils 23a and 24a. Is adjusted.

  The torque converter 3 has a pump-side shell 3 a connected to the crankshaft 2 and a turbine runner 3 b connected to the torque converter output shaft 19. The torque converter output shaft 19 has a front fixed to the pump-side shell 3 a. A lockup clutch 28 that is pressed against the cover 27 and transmits engine torque is attached. An apply chamber 28a is formed on one side of the lockup clutch 28 to which control hydraulic pressure is applied to press and engage the lockup clutch 28 against the front cover 27, and the release chamber is released on the other side. A chamber 28b is formed. By circulating the hydraulic pressure supplied to the release chamber 28b through the apply chamber 28a, the lock-up clutch 28 is released and the torque converter 3 is activated. On the other hand, by adjusting the hydraulic pressure supplied to the release chamber 28b, the lock-up clutch enters a half-clutch state, that is, a slip state.

  The speed change control device 30 includes a pulley rotation speed sensor 31 that detects the rotation speed of the primary pulley 7, a vehicle speed sensor 32 that detects the traveling speed of the vehicle, and a D range and R selected by the driver operating the select lever. The range detection sensor 33 for detecting a travel range such as a range, the throttle sensor 34 for detecting the opening of the throttle valve of the engine 1, the brake sensor 35 for detecting whether or not the brake pedal is operated, and the operating state of the lockup clutch 28 Detection signals from a lock-up operation state detecting means 36 for detecting the engine speed, an engine speed sensor 37 for detecting the engine speed, an ABS sensor 38 for detecting the working state of the ABS (anti-lock brake system), etc. It has become. ABS is a device that prevents wheel locks that occur during sudden braking or braking on slippery roads such as snowy roads.

  In order to detect the throttle opening, an accelerator sensor that detects the opening of the accelerator pedal or an idling sensor that detects that the engine is in an idling state may be used in place of the throttle sensor 34. good. Further, as the vehicle speed sensor 32, a sensor that detects the rotational speed of the secondary pulley may be used to calculate the vehicle speed from the rotational speed.

  This continuously variable transmission has an automatic transmission mode in which the transmission is automatically set according to the driving state and a manual mode in which the gear ratio is set by manual operation. Can switch between automatic mode and manual mode.

  The speed change control device 30 includes a microprocessor that calculates current values for the solenoid coils 23a and 24a based on signals from respective sensors and the like, and a memory that stores a control program, an arithmetic expression, and map data. .

  This continuously variable transmission has a basic shift characteristics map that controls the gear ratio, engine speed, or primary pulley speed based on parameters such as throttle opening, and the driver releases the accelerator pedal. In this state, the vehicle has a speed change characteristic map that is set to an inertial traveling mode for applying engine braking when the vehicle is in an inertial traveling state where the vehicle is traveling on a downhill road, that is, an inertial traveling state. In this inertial running mode, the lower limit value of the target rotational speed is increased so as to increase the target rotational speed of the primary pulley in order to downshift the gear ratio.

Under the state where the vehicle is traveling in the inertial traveling mode, as described above, the correction is made so that the lower limit value of the target rotational speed is increased, but the inertial state where the accelerator pedal is depressed under this state. At the time of traveling cancellation, the lower limit value of the target rotational speed during inertia traveling is corrected based on the throttle opening and the vehicle speed without changing the rotational speed to the lower limit value in the basic shift characteristic map during normal traveling. .

FIG. 2 is a speed change characteristic diagram showing the relationship between the target rotational speed Np of the primary pulley based on the throttle opening TH and the vehicle speed V at this time. In this way, when the accelerator pedal is depressed and the inertial traveling is released under the inertial traveling state, the lower limit value is lower than the lower limit value of the target rotational speed set with priority on the engine brake during the inertial traveling. The lower limit value is changed according to the throttle opening TH and the vehicle speed V.

In FIG. 3, the rate of change of the rotational speed is changed based on the vehicle speed V when the inertial traveling is released when the accelerator pedal is depressed in the inertial traveling state. FIG. 3A shows a change rate characteristic diagram in which the change rate lower limit value is changed based on the vehicle speed, and FIG. 3B is a change rate in which the change rate upper limit value is changed based on the vehicle speed. A characteristic diagram is shown. As shown in the figure, the rate of change of the rotational speed is changed in accordance with the vehicle speed V, and since it is less necessary to apply the engine brake in the high vehicle speed region of V2 or higher than in the low vehicle speed region, the speed is gradually downshifted. In the following low vehicle speed range, the downshift speed is increased. Further, in the extremely low vehicle speed region of V1 or lower, the downshift is performed gently as in the high vehicle speed region. For example, the vehicle speed V1 is about 25 km / h, and the vehicle speed V2 is about 50 km / h.

  On the other hand, in an extremely low vehicle speed region of V1 or less and a high vehicle speed region of V2 or more, in a region where it is not necessary to apply the engine brake in order to make the upshift more gently, a sudden change in rotation is suppressed, The uncomfortable feeling due to the rotation change is reduced.

  Map data corresponding to the speed change characteristic diagrams shown in FIGS. 2 and 3 during inertial running are stored in the memory of the speed change control device 30, and each speed change characteristic is obtained by searching the map data according to the running state. Is set.

  Next, shift control in the transmission of the present invention will be described with reference to a flowchart.

  FIG. 4 is a flowchart showing a main routine for setting the rotation speed and the gear ratio of the primary pulley, and is executed at predetermined intervals. First, as is well known, the target primary rotational speed Np is set in step S1 with reference to the basic shift characteristic map based on parameters such as the accelerator opening and the vehicle speed or the engine rotational speed. In step S2, an inertia traveling determination process is executed. In step S3, an upper limit value of the target rotational speed Np is set. In step S4, a lower limit value of the target rotational speed Np is set. In step S5, the target rotational speed change amount is set. An upper limit value is set, and in step S6, a lower limit value of the target rotational speed change amount is set.

  In step S7, an upper limiter process for the target rotational speed Np is executed, in step S8, a lower limiter process for the target rotational speed Np is executed, in step S9, an upper limiter process for the target rotational speed change amount is executed, and in step S10, the target upper limiter process is executed. A lower limiter process for the rotational speed change amount is executed. Thereafter, steps S11 to S16 are executed, and the optimum target rotational speed and gear ratio are set according to the traveling state of the vehicle.

  FIG. 5 is a flowchart showing a subroutine of the inertia traveling determination process in step S2 of FIG. 4. In step S21, it is determined whether or not an inertia traveling determination prohibition flag is set. If the inertial travel determination prohibition flag is on, the inertial travel determination flag is set to off in step S22. If the inertial travel determination prohibition flag is off, the inertial travel determination in step S23 and the inertial travel determination in step S24 are performed. Processing is executed.

[Inertia driving mode judgment condition]
The inertia traveling mode for applying the engine brake when traveling downhill is set when all of the following conditions are satisfied. The conditions are as follows: first, the vehicle is traveling in a travel range other than the parking range P, neutral range N, and reverse range R; second, the vehicle speed is within a predetermined range; One condition is satisfied continuously for a predetermined time or more. The three conditions are that when the lockup is released, the actual primary engine speed Npi is greater than the engine engine speed Ne, the acceleration / deceleration exceeds a predetermined value, the accelerator pedal is released and the engine engine speed is idling. That is. When these conditions are satisfied, the inertia traveling mode is set.

FIG. 6 is a flowchart showing the inertial travel determination subroutine in FIG. 5. When it is determined in step S31 that the inertial travel determination flag is not on, it is determined in step S32 whether or not the travel range D is present. In S33, it is determined whether or not the vehicle speed is within a predetermined range. In Step S34, it is determined whether or not the acceleration / deceleration determination 1 flag is turned on. If YES is determined in these steps S32 to S34, the inertia traveling determination flag is turned on in step S35. If YES is determined in step S31 and if NO is determined in steps S32 to S34, the routine is directly exited.

FIG. 7 is a subroutine for turning on / off the acceleration / deceleration determination 1 flag. In step S41, it is determined whether the inertial travel determination flag is on . If the inertial travel determination flag is not on , the torque converter 3 is locked in step S42. It is determined whether or not the up clutch 28 is engaged. If the up clutch 28 is not engaged, it is determined in step S43 whether or not the actual primary pulley rotational speed Npi is higher than the engine rotational speed Ne by a predetermined value Ns1 or more. Further, in step S44, it is determined whether or not the acceleration / deceleration of the vehicle is greater than a predetermined value α. In step S45, it is determined whether or not the accelerator is released.

In step S46, it is determined whether or not the timer T1 has passed the predetermined time Ta. If it is determined that the predetermined time has not elapsed, the unit time is increased in step S48, and the predetermined time has elapsed. If it is determined, the acceleration / deceleration determination 1 flag is turned on in step S47. On the other hand, if it is determined in step S41 that the inertia traveling determination flag is ON , or if NO is determined in each of steps S43 to S45, the timer T1 is reset in step S49, and the inertia traveling is performed in step S50. Turn off the judgment flag.

  Therefore, by executing the routines of FIGS. 6 and 7, it is determined whether or not to execute the inertial running mode described above.

[Inertia drive mode release conditions]
The inertial running mode is canceled when any of the following conditions is satisfied.
One of the conditions is that the driver operates the select lever in a range other than the travel range D, for example, any one of the parking range P, the neutral range N, and the reverse range R. The other one of the conditions is that the idling state is turned off by depressing the accelerator pedal, and when the inertia traveling mode is canceled according to the condition, the target rotational speed is reset to the original rotational speed immediately after the cancellation. Therefore, the change amount limiting process is not performed. Another one of the conditions is that the vehicle speed is out of a predetermined range. Furthermore, another one of the conditions is that the following four conditions are continuously satisfied for a predetermined time or more. The first condition is that the engine speed Ne is changed from the primary speed Np during lock-up release. When the subtracted value is larger than the predetermined value, the second condition is idling, the third is when the brake is released, and the fourth is when the acceleration / deceleration is less than the predetermined value. In the case where all of these states continue for a predetermined time, the inertial running mode is canceled.

FIG. 8 is a subroutine showing the inertia traveling cancellation shown in step S23 of FIG. 5. In step S51, it is determined whether or not the inertia traveling determination flag described above is ON . If the determination flag is on, it is determined in step S52 whether or not a travel range is selected. In step S53, it is determined whether or not the vehicle speed is outside a predetermined range. In step S54, whether the accelerator is depressed. In step S55, it is determined whether or not the target primary rotational speed Np is larger than the inertia traveling primary rotational speed lower limit Npd.

  If NO in step S52 or YES in step S53, step S61 is executed and the inertia traveling determination flag is turned off. If NO is determined in step S54 or NO is determined in step S55, the timer T2 is reset in step S59. In step S56, it is determined whether or not the timer T2 is equal to or greater than a predetermined value Tb. If it is equal to or greater than the predetermined value, the limiter unnecessary flag is turned on in step S57 and the routine is exited through the above-described step S61. If not, the timer T2 is increased by unit time in step S58, and it is determined in step S60 whether acceleration / deceleration determination 2 is on.

FIG. 9 is a flowchart showing the acceleration / deceleration determination 2 subroutine. In step S71, it is determined whether or not the inertia traveling determination flag is on . In step S72, it is determined whether or not the lockup clutch 28 is engaged. When the lockup clutch 28 is not engaged, if the lockup clutch 28 is not engaged, the value obtained by subtracting the engine rotation speed Ne from the actual primary rotation speed Npi is equal to or greater than the predetermined value Ns2. In step S74, it is determined whether the acceleration / deceleration is equal to or less than a predetermined value. In step S75, it is determined whether the accelerator is released. In step S76, it is determined whether the brake is released. Judging.

  When the above conditions are satisfied, if it is determined in step S77 that the timer T3 is equal to or greater than the predetermined value Tc, the acceleration / deceleration determination 2 flag is set to ON in step S78. If not, the timer T3 is increased by unit time in step S79. On the other hand, when the conditions in steps S71 and S73 to S76 are not satisfied, the timer T3 is cleared in step S80, and the acceleration / deceleration determination 2 flag is set to OFF in step S81.

[Prohibition of inertial running judgment]
The inertial running mode is executed when the above-mentioned conditions are satisfied. However, if there is a possibility that the inertial running determination is erroneously determined as described below, the inertial running determination is prohibited and the inertial running rotation is performed. The calculation of the lower limit of the number is prohibited, it is possible to avoid unnecessary downshift due to control malfunction, and to travel without a sense of incongruity, and to improve the traveling performance of the vehicle.

  FIG. 10 is a flowchart showing a subroutine for inertial inertia determination prohibition. In steps S91 and S92, it is determined whether the prohibition rapid deceleration determination flag and the prohibition rapid acceleration determination flag are turned on, respectively. In step S93, a shift hold is performed. It is determined whether or not is in operation and within a predetermined time since it has been inactive. In step S94, whether or not the ABS is in operation and within a predetermined time since the ABS has been inactive. In step S95, it is determined whether or not the vehicle speed sensor 32 is out of order and whether or not the vehicle speed sensor 32 is within a predetermined time since it is OK. In step S96, whether or not the manual mode is set. Whether or not it is within a predetermined time after the manual mode is released is determined. If YES is determined in any of steps S91 to S96, the inertia traveling determination prohibition flag is turned on in step S97. If NO is determined in all of steps S91 to S96, inertia is determined in step S98. The travel determination prohibition flag is turned off. Here, the failure of the vehicle speed sensor in step S95 detects a failure of the secondary rotation speed sensor when the vehicle speed is detected by the secondary rotation speed sensor.

  FIG. 11 is a flowchart showing a subroutine of prohibition rapid deceleration determination. In step S101, it is determined whether or not the acceleration / deceleration is equal to or less than the determination acceleration / deceleration DECL. If so, the timer T4 sets a predetermined determination time in step S102. Judge whether or not it has passed. If the predetermined determination time has elapsed, the prohibition rapid deceleration determination flag is turned on in step S103, and the timer T5 is reset in step S104. On the other hand, if the predetermined determination time has not elapsed, the timer T4 is increased by unit time in step S105.

  If NO is determined in step S101, it is determined whether or not the acceleration / deceleration is greater than or equal to the determination acceleration DECH in step S106. If so, whether or not the timer T5 has passed the release time in step S107. Judging. If the predetermined release time has elapsed, the prohibition rapid deceleration determination flag is turned off in step S108, and the timer T4 is reset in step S109. On the other hand, if the predetermined release time has not elapsed, the timer T5 is increased by unit time in step S111. If NO is determined in step S106, the timer T5 is reset in step S110.

  FIG. 12 is a flowchart showing a prohibition rapid acceleration determination subroutine. In step S121, it is determined whether or not the acceleration / deceleration is equal to or greater than a predetermined determination acceleration / deceleration INCH. If it is equal to or greater, the timer T6 determines in step S122 the determination delay time. It is determined whether or not. If the predetermined determination delay time has elapsed, the prohibition rapid acceleration determination flag is turned on in step S123, and the timer T7 is reset in step S124. On the other hand, if the predetermined judgment delay time has not elapsed, the timer T6 is increased by unit time in step S125.

  If NO is determined in step S121, it is determined in step S126 whether or not the acceleration / deceleration is equal to or less than a predetermined determination acceleration / deceleration INCL. If so, the timer T7 has passed the release delay time in step S127. Judge whether or not. If the release delay time has elapsed, the prohibition rapid acceleration determination flag is turned off in step S128, and the timer T6 is reset in step S129. On the other hand, if the predetermined release delay time has not elapsed, the timer T7 is increased by unit time in step S131. If NO is determined in step S126, the timer T7 is reset in step S130.

[Set target lower limit value for inertial driving]
FIG. 13 is a flowchart showing a subroutine for setting the lower limit value of the target rotational speed Np shown in step S4 of FIG. 4. In step S141, the target rotational speed lower limit value NPMINNORM at normal time is calculated, and the inertial running determination is prohibited in step S142. It is determined whether or not. If not prohibited, it is determined in step S143 whether or not the normal target rotational speed lower limit value NPMINNORM set in step S141 is larger than the inertia traveling target rotational speed lower limit value Npd. Here, the target rotational speed lower limit value NPMINNORM at the normal time is determined by the OD (overdrive) line or the minimum speed change line of the vehicle speed line map. If YES is determined in this step S143, the target rotational speed lower limit value is set to the normal target rotational speed lower limit value NPMINNORM in step S144. On the other hand, if NO is determined in step S143, the target rotational speed lower limit value is set to the inertial traveling target lower limit value Npd in step S146. If it is determined in step S142 that the inertia traveling determination is prohibited, the inertia traveling target revolution lower limit value Npd and the inertia traveling lower limit value NPMINDAKOU0 are set to the normal target rotational speed lower limit value NPMINNORM in step S145.

  In this way, when the vehicle is traveling on a downhill road in an inertial manner, the lower limit of the target rotational speed for inertial travel of the primary pulley is set when the vehicle exceeds a predetermined acceleration / deceleration, and the engine Brake force can be obtained.

FIG. 14 is a flowchart showing a subroutine for calculating the lower limit value NPMINDAKOU0 at the time of inertial traveling control. When it is determined in step S147 that the inertial traveling determination flag is on , the map shown in FIG. 2 is used in step S149. Set the lower limit. On the other hand, if the inertial running determination is not in progress, the target rotational speed lower limit NPMINNORM at the normal time is set in step S148.

  As described above, when the accelerator pedal is depressed during inertial traveling, the lower limit value is corrected based on the throttle opening and the vehicle speed. Therefore, when the accelerator is released again from a state where the accelerator is slightly depressed, You can get the original necessary engine brakes.

[Change rate setting]
When the accelerator pedal is depressed during inertial traveling, the lower limit value of the target rotational speed for inertial traveling is corrected based on the vehicle speed, as shown in FIG. Thus, by applying the rotational speed change rate limit value determined by the vehicle speed, it prevents the engine speed fluctuation in the time that has released this inertial running control, seamlessly ranging from low speed to high speed, A A feeling of upshift and downshift can be obtained.

  FIG. 15 is a flowchart showing a change amount limiter calculation subroutine for setting the upper limit value and the lower limit value of the target rotation speed change amount in steps S5 and S6 shown in FIG. 4. In step S151, the flow chart shown in FIG. In step S152, the change rate lower limit value is calculated from the change rate table based on the vehicle speed shown in FIG. 3B.

  FIG. 16 is a flowchart showing a subroutine for calculating the lower limit value Npd during inertial travel after setting the rate of change during inertial travel using the rate of change limiter. In step S171, it is determined whether or not the limiter unnecessary flag is turned on. If it is determined that the limiter is not turned on, the limiter unnecessary flag is turned off in step S177, the lower limit value Npd for inertial running is set to NPMINDAKOU0 in step S178, and the process proceeds to step S176. On the other hand, if it is determined in step S171 that the limiter unnecessary flag is off, the inertial traveling target rotational speed lower limit value Npd calculated in the previous routine in step S172, that is, Npd-1 is the inertial traveling target rotational speed lower limit value. It is determined whether or not it matches the value NPMINDAKOU0.

  In step S173, it is determined whether or not prohibition determination is turned on by deceleration. In step S174, it is determined whether or not prohibition determination is turned on by convergence. If the prohibition determination is turned off in these steps, The change amount limiter process 2 in step S175 is executed, and the change rate restriction process prohibition flag is set in step S176. When any of steps S172 to S174 is established, the routine is exited through steps S178 and S176 described above.

  FIG. 17 is a flowchart showing a subroutine of change amount limiter processing 2 shown in step S175 of FIG. 16. In step S181, it is determined whether or not the previous lower limit value Npd-1 of the target rotational speed is larger than NPMINDAKOU0. If YES is determined in this step, the target rotational speed lower limit value Npd is set to Npdn−1 plus the change rate lower limit value in step S182. If NO is determined, Npdn−1 is determined in step S185. Npd is set to a value obtained by adding a change rate upper limit value to. In step S183, it is determined whether Npdn-1 is smaller than NPMNDAKOU0. If Npdn-1 is smaller, NPMNDAKOU0 is set to the inertial traveling target lower limit value Npd in step S184. In step S186, it is determined whether or not Npd is larger than NPMINDAKOU0. If it is larger, the process proceeds to step S187, where NPMINDAKOU0 is set to the inertia traveling target revolution lower limit value Npd.

[Control during sudden deceleration]
When sudden deceleration is performed by depressing the brake while the inertia traveling mode is being executed on a downhill road, it is prohibited to limit the rate of change to set the lower limit value of the target rotational speed for inertia traveling Like to do. As a result, when sudden deceleration is performed, the gear ratio can be controlled quickly and the target gear ratio can be followed. As a result, even when sudden deceleration is performed at a low vehicle speed, it is possible to prevent a high engine speed from being maintained and excessive engine braking. This prohibition of the change rate restriction is executed even when the lower limit value after the limiter converges to the rotation speed lower limit value before the change amount limiter.

  FIG. 18 is a flowchart showing a subroutine for determining a change rate restriction prohibition due to deceleration. In step S191, it is determined whether the brake is depressed. In step S192, it is determined whether the vehicle speed is equal to or lower than a predetermined value. In step S193, it is determined whether the acceleration / deceleration is equal to or less than a predetermined value A. If all these conditions are met and it is determined in step S194 that the timer T8 is equal to or greater than the predetermined value Td, the flag for prohibition determination by deceleration is turned on in step S195, and the timer T9 is reset in step S196. To do. On the other hand, if it is determined that the value is equal to or less than the predetermined value Td, the timer T8 is increased in step S197.

  When the acceleration / deceleration exceeds the predetermined value A in step S193, the process proceeds to step S198, where it is determined whether or not the acceleration / deceleration is greater than or equal to the predetermined value B. In step S199, it is determined whether or not the timer T9 is greater than or equal to the predetermined value Te. If each condition is satisfied, the flag for prohibition determination by deceleration is turned off in step S200, and the timer T8 is reset in step S201. On the other hand, if it is determined that the value is equal to or less than the predetermined value Te, the timer T9 is increased in step S202. If it is determined in step S198 that the acceleration / deceleration is not more than the predetermined value B, the timer T9 is reset in step S203.

  On the other hand, when the brake is depressed in step S191 described above, or when the vehicle speed exceeds a predetermined value in step S192, the routine exits through steps S200 and S201 described above.

  FIG. 19 is a flowchart showing a subroutine for setting a change rate control process prohibition flag due to convergence. In step S210, it is determined whether Npd and NPMNDAKOU0 match. In S211, a determination prohibition flag due to convergence is set. In step S212, it is determined whether or not a change in the inertia traveling determination flag has been detected, that is, whether the flag has been switched from on to off or from on to off. If Npd and NPMNDAKOU0 do not match in step S210, or if YES is determined in step S212, step S213 is executed to turn off the prohibition determination due to convergence.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  For example, the target rotational speed and the inertial traveling rotational speed described above are the rotational speeds of the input side rotor of the continuously variable transmission, that is, the primary pulley, but the respective rotational speeds may be the engine rotational speed. Further, in the above-described shift control, the inertia traveling direction rotation speed and the lower limit value change rate are controlled. However, the inertia traveling speed is set to the inertia traveling speed ratio, and the inertia traveling rotation speed lower limit value change rate is set. May be the inertia traveling speed ratio change rate. The continuously variable transmission shown in the figure is a belt-type transmission, but may be a toroidal transmission.

Effect of the invention

  According to the present invention, when acceleration is started by depressing the accelerator under a state where the vehicle is running inertially so that the engine brake is applied on the downhill road, it is possible to prevent the engine from excessively rotating. Acceleration and vibration noise can be mitigated, and even if the accelerator is opened slightly, unnecessary rotation fluctuations can be prevented, and when the accelerator is opened again, the engine brake control can be resumed promptly. Inertia travel control can be performed without any sense of incongruity. Thereby, a moderate engine brake can be obtained when traveling on a downhill road, and traveling performance can be improved.

  It is the schematic which shows the drive system of the belt-type continuously variable transmission which is an example of a continuously variable transmission.   FIG. 6 is a shift characteristic diagram showing a relationship between a target rotational speed of a primary pulley based on a throttle opening and a vehicle speed.   (A) is a change rate characteristic diagram in which the change rate lower limit value is changed based on the vehicle speed, and (B) is a change rate characteristic diagram in which the change rate upper limit value is changed based on the vehicle speed. is there.   It is a flowchart which shows the main routine of transmission control.   It is a flowchart which shows the subroutine of inertial running determination processing.   It is a flowchart which shows the subroutine of inertial running determination.   It is a flowchart which shows the subroutine of acceleration / deceleration determination 1.   It is a flowchart which shows the subroutine of inertial running cancellation | release.   It is a flowchart which shows the subroutine of acceleration / deceleration determination 2. FIG.   It is a flowchart which shows the subroutine of prohibition of inertial running determination.   It is a flowchart which shows the subroutine of prohibition rapid deceleration determination.   It is a flowchart which shows the subroutine of prohibition rapid acceleration determination.   It is a flowchart which shows the subroutine of target rotation speed lower limit setting.   It is a flowchart which shows the subroutine of the lower limit calculation of inertial running control.   It is a flowchart which shows the subroutine of change amount limiter calculation.   It is a flowchart which shows the subroutine of the lower limit calculation at the time of inertial running.   10 is a flowchart showing a subroutine of change amount limiter processing 2;   It is a flowchart which shows the subroutine of the change rate restriction | limiting prohibition by deceleration.   It is a flowchart which shows the subroutine of a change rate restriction | limiting process prohibition flag setting.

1 Engine 3 Torque converter 5 Primary shaft 6 Secondary shaft 7 Primary pulley 8 Secondary pulley 9 Belt (power transmission element)
21 Oil pump 23 Secondary pressure adjustment valve 24 Primary pressure adjustment valve 30 Shift control device 31 Pulley rotation speed sensor 32 Vehicle speed sensor 33 Range detection sensor 34 Throttle sensor 35 Brake sensor 36 Lockup clutch operating state detection means 37 Engine rotation speed sensor 38 ABS Sensor

Claims (1)

A transmission control device for a continuously variable transmission that changes the rotation of an input-side rotator steplessly via a power transmission element and transmits it to an output-side rotator,
Vehicle speed detecting means for detecting the traveling speed of the vehicle;
A throttle sensor for detecting the throttle opening;
Inertia traveling detection means for detecting that the vehicle is traveling inertia on a downhill road;
A lower limit value setting means for setting a target rotational speed lower limit value for inertial travel of the input side rotor when the inertial travel detection means detects that the vehicle is traveling on a downhill road inertially;
Lower limit limit that sets the lower limit value of the target rotational speed of the input side rotor to a lower value than that during inertial travel, based on the throttle opening and vehicle speed, when the inertial travel is released when the accelerator pedal is depressed during inertial travel. Means,
When the inertial running is canceled, when the vehicle speed is in the high vehicle speed region and in the extremely low vehicle speed region, the lower limit value of the change rate of the rotational speed of the input side rotating body is increased and the input side rotating body Change rate correction means for correcting so as to lower the upper limit value of the change rate of the rotational speed ;
A transmission control device for a continuously variable transmission.

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