JP6110676B2 - Shift control device for continuously variable transmission - Google Patents

Description

  The present invention relates to a speed change control device for a continuously variable transmission capable of shifting in a multi-speed mode with a fixed gear ratio.

  Conventionally, belt-type and toroidal-type continuously variable transmissions are known as continuously variable transmissions used in vehicles such as automobiles. For example, a belt-type continuously variable transmission has a primary pulley provided on an input shaft, a secondary pulley provided on an output shaft, and a power transmission element such as a belt or a chain spanned between these pulleys. By changing the groove width of the power transmission element and changing the winding diameter of the power transmission element, the transmission ratio is continuously changed to transmit the rotation of the input shaft to the output shaft.

  In such a continuously variable transmission, the gear ratio is automatically controlled based on a parameter indicating an operating state. That is, in the transmission control device for a continuously variable transmission, for example, based on a predetermined shift characteristic, a target primary rotational speed using the accelerator opening and the vehicle speed as parameters is set, and the target primary rotational speed is set to the actual primary rotational speed. The gear ratio is controlled so that the primary rotational speed converges.

  By the way, when the above-described continuously variable transmission control is performed in the continuously variable transmission, the gear ratio changes steplessly, so it may be difficult to obtain moderate acceleration like a multi-stage transmission. . On the other hand, many shift control devices having a multi-speed mode that controls a fixed gear ratio of a plurality of shift speeds that have been set in advance have been proposed. Accordingly, the shift control mode of the continuously variable transmission can be selectively switched between the continuously variable transmission mode and the multi-speed transmission mode (manual transmission mode) (see, for example, Patent Document 1). .

Japanese Patent No. 4046999

  However, in the technique for switching the shift control mode according to the shift operation or the like as described above, a frequent shift operation or the like by the driver may be required.

  The present invention has been made in view of the above circumstances, and the shifting of the continuously variable transmission mode and the multi-speed transmission mode can be realized at a timing without any sense of incongruity without relying on a shift operation or the like. An object is to provide a control device.

A transmission control apparatus for a continuously variable transmission according to an aspect of the present invention transmits rotation of an input-side rotating body driven by an engine to an output-side rotating body by continuously changing a gear ratio via a power transmission element. A continuously variable transmission control device for a continuously variable transmission, a continuously variable transmission means for continuously controlling the speed ratio based on a preset continuously variable transmission characteristic, a preset multi-stage upshift characteristic, and a downshift a multi-speed means for controlling the gear ratio to a fixed speed ratio of the gear position selected by the select gear position based on a multi-speed characteristic having a shift characteristic, based on the parameters of operating conditions including accelerator opening, wherein Mode switching means for selectively switching a speed control mode to be executed for the continuously variable transmission between the continuously variable transmission mode by the continuously variable transmission means and the multi-speed transmission mode by the multi-speed transmission means; , The mode switching means, during the execution of the multi-speed mode, the accelerator opening becomes less than the set threshold value, the upshift decision to the gear of the high speed side is performed, and is selected by the upshift determination The rotation speed of the input-side rotator calculated from the fixed gear ratio of the shift speed is the maximum target rotation speed of the input-side rotator that can be set in the continuously variable transmission mode after a preset delay time has elapsed. When it is determined that the value is lower than the value, switching from the multi-speed mode to the continuously variable mode is determined.

  According to the transmission control device for a continuously variable transmission of the present invention, switching between the continuously variable transmission mode and the multi-speed transmission mode can be realized at a timing without any sense of incongruity without depending on a shift operation or the like.

System configuration diagram of drive system with continuously variable transmission Flowchart showing a shift control mode switching control routine Characteristic diagram showing an example of gear shifting characteristics in continuously variable transmission mode A characteristic diagram showing an example of a speed change characteristic in the multi-speed mode Explanatory drawing showing the relationship between the target turbine speed at the multi-stage transition opening in the continuously variable transmission mode and the target turbine speed at each gear position in the multi-speed mode. Explanatory drawing showing the main part of the corrected downshift characteristics Explanatory drawing showing an example of the transition of the target primary rotational speed when switching from the multi-speed mode to the continuously variable speed mode Explanatory drawing which shows an example of the relationship between each target primary rotation speed at the time of determining switching from multi-stage transmission mode to continuously variable transmission mode, and a differential rotation threshold value Explanatory drawing which shows the map of a difference rotation threshold value Explanatory drawing which shows an example of the relationship between the accelerator opening and the primary rotation speed when switching from the multi-speed mode to the continuously variable speed mode

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is a system configuration diagram of a drive system provided with a continuously variable transmission, FIG. 2 is a flowchart showing a shift control mode switching control routine, and FIG. 3 is a shift in a continuously variable transmission mode. FIG. 4 is a characteristic diagram showing an example of a shift characteristic in the multi-stage shift mode, and FIG. 5 is a target turbine speed at a multi-stage transition opening in the continuously variable shift mode and each shift stage in the multi-stage shift mode. FIG. 6 is an explanatory diagram showing a main part of the corrected downshift characteristic, and FIG. 7 is a target primary rotational speed when the multi-speed mode is switched to the continuously variable mode. FIG. 8 is an explanatory diagram showing an example of the transition of the engine, and FIG. 8 is an explanatory diagram showing an example of the relationship between each target primary rotation speed and the differential rotation threshold when switching from the multi-speed mode to the continuously variable mode is determined. 9 is an explanatory diagram showing a map of the differential rotation threshold, FIG. 10 is an explanatory diagram showing an example of the relationship between the accelerator opening and the primary rotation speed at the time of switching to the continuously variable transmission mode from the multi-speed mode.

  In FIG. 1, reference numeral 1 denotes an engine mounted on a vehicle such as an automobile (host vehicle). A continuously variable transmission 3 is connected to the output side of the engine 1 via a torque converter 2. The output torque from the engine 1 is transmitted to the continuously variable transmission 3 via the fluid of the torque converter 2 or via a lockup clutch (not shown) in the lockup engagement state. After being shifted at a predetermined gear ratio, the output shaft 4 is transmitted to driving wheels such as rear wheels or front wheels.

  The engine 1 has an electronically controlled throttle device (ETC) 6 in the middle of an intake passage 5 communicating with an intake port (not shown). The ETC 6 has a throttle actuator 7 for opening and closing the throttle valve 6a. When the throttle actuator 7 is driven according to a drive signal from an engine control unit (ECU) 20, the throttle valve 6a The throttle opening is controlled.

  The continuously variable transmission 3 is arranged in parallel with the primary shaft 10, in which the rotation of the crankshaft 1 a driven by the engine 1 is transmitted via the torque converter 2 and the forward / reverse switching device 9. Secondary shaft 11.

  The primary shaft 10 is provided with a primary pulley 15 as an input side rotating body. The primary pulley 15 includes a fixed pulley 15 a that is integrally fixed to the primary shaft 10 and a movable pulley 15 b that is slidably attached to the primary shaft 10.

  The secondary shaft 11 is provided with a secondary pulley 16 as an output side rotating body. The secondary pulley 16 includes a fixed pulley 16 a that is integrally fixed to the secondary shaft 11 and a movable pulley 16 b that is slidably attached to the secondary shaft 11.

  A chain 17 as a power transmission element is stretched between the primary pulley 15 and the secondary pulley 16, and the ratio of the winding diameter of the chain 17 to each pulley is changed by changing the groove width of both pulleys 15 and 16. By changing the rotation, the rotation of the primary shaft 10 is steplessly changed and transmitted to the secondary shaft 11. That is, assuming that the winding diameter of the chain 17 around the primary pulley 15 is Rp and the winding diameter of the chain 17 around the secondary pulley 16 is Rs, the rotation of the primary shaft 10 is changed at a pulley ratio (speed ratio) i = Rs / Rp. Then, it is transmitted to the secondary shaft 11.

  In order to change the groove width of the primary pulley 15, the movable pulley 15b is provided with a primary hydraulic chamber 15c, and a primary pressure adjusting valve (not shown) is connected to the primary hydraulic chamber 15c. Further, in order to change the groove width of the secondary pulley 16, a secondary hydraulic chamber 16c is provided in the movable pulley 16b, and a secondary pressure adjusting valve (not shown) is connected to the secondary hydraulic chamber 16c. An oil pump (not shown) driven by the engine 1 or an electric motor is connected to the primary pressure adjusting valve and the secondary pressure adjusting valve. The primary pressure adjusting valve and the secondary pressure adjusting valve respectively adjust the hydraulic pressure of the hydraulic oil supplied from the oil pump to the hydraulic chambers 15c and 16c in accordance with the drive signal from the transmission control unit (TCU) 21. Thus, the groove widths of the pulleys 15 and 16 are variably controlled.

  The TCU 21 detects, for example, a vehicle speed sensor 27 that detects a vehicle speed (own vehicle speed) V and a rotation speed of the primary shaft 10 (primary rotation speed = turbine rotation speed) as sensors for detecting the driving state of the host vehicle. The primary rotational speed sensor 28 that performs the secondary rotational speed sensor 29 that detects the rotational speed (secondary rotational speed) of the secondary shaft 11 is connected. In addition, the ECU 20 is connected to the TCU 21 via a communication line such as CAN so that mutual communication is possible. For example, an engine speed sensor 25 for detecting the engine speed Ne, an accelerator position sensor 26 for detecting the accelerator position θacc, and the like are connected to the ECU 20 as sensors for detecting the driving state of the host vehicle. Various detection signals from these sensors are input to the TCU 21 via a communication line. Here, the accelerator opening degree θacc is closely related to the throttle opening degree, and the throttle opening degree or the like can be used instead of the accelerator opening degree θacc in the shift control mode switching control described later. . That is, in this embodiment, the accelerator opening includes the throttle opening and the like in a broad sense.

  In the TCU 21, for example, speed change characteristics for continuously controlling the speed ratio of the continuously variable transmission 3 are mapped and stored. This continuously variable transmission map is for setting the target rotational speed (target primary rotational speed Nn) of the primary shaft 10 using, for example, the vehicle speed V and the accelerator opening θacc as parameters. For this reason, in the continuously variable transmission map, for example, as shown in FIG. 3, a shift line for setting a target primary rotational speed Npt_n suitable for the vehicle speed V from the viewpoint of fuel consumption, exhaust gas characteristics, etc. Is set for each predetermined accelerator opening θacc. The TCU 21 can calculate the target primary rotational speed Npt_n based on the vehicle speed V and the accelerator opening θacc with interpolation calculation by referring to such a continuously variable transmission map. The TCU 21 can control the gear ratio steplessly by converging the primary rotational speed Np to the target primary rotational speed Npt_n.

  In addition, the TCU 21 replaces the above-described shift control in which the gear ratio is controlled steplessly (shift control in the continuously variable transmission mode) with a preset multi-stage shift stage (for example, seven shift stages). It is possible to perform shift control using a fixed gear ratio (shift control using a multi-stage shift mode). For this reason, for example, shift characteristics having an upshift characteristic and a downshift characteristic corresponding to each shift stage are stored in the TCU 21 in advance as a map. That is, for example, as shown in FIG. 4, a shift line for performing an upshift determination or a downshift determination for the current shift stage is set in this multi-stage shift map using the vehicle speed V and the accelerator opening θacc as parameters. Has been. In the figure, the upshift side shift line is indicated by a solid line, and the downshift side shift line is indicated by a broken line. In the multi-speed shift map shown in the figure, hysteresis is provided by arranging the shift line on the upshift side at a higher speed side than the shift line on the downshift side, thereby preventing control hunting at the time of shift. ing. This multi-stage shift map is basically set by previously obtaining a shift schedule that matches the output characteristics of the engine 1 from experiments or the like. When the TCU 21 determines an upshift or a downshift based on the multi-speed shift map, the TCU 21 can control the speed ratio to a new fixed speed ratio.

Thus, in this embodiment, TCU21 implement | achieves each function as a continuously variable transmission means and a multistage transmission means. Further, the TCU 21 has a function as a mode switching means for selectively switching the shift control mode of the continuously variable transmission 3 between the continuously variable transmission mode and the multi-speed transmission mode.

  Here, the TCU 21 always calculates the target primary rotational speed Npt_n corresponding to the continuously variable transmission mode even when the continuously variable transmission mode is not selected. Further, for example, as indicated by a broken line in FIG. 3, the primary rotational speed at each gear position (fixed gear ratio) in the multi-speed mode is basically linearly changed according to the vehicle speed. Always calculates such a primary rotational speed as the target primary rotational speed Npt_s corresponding to the multi-speed mode.

  The mode switching control in the TCU 21 is performed based on parameters indicating a predetermined operation state including the accelerator opening θacc, for example. That is, the TCU 21 basically selects the continuously variable transmission mode in which the fuel efficiency is emphasized in a region where the accelerator opening θacc is small, and the occupant feels acceleration in the region where the accelerator opening θacc is large. The multi-speed mode that can be selected is selected.

  Specifically, when the continuously variable transmission mode is selected, the TCU 21 is one of the conditions that the accelerator opening θacc exceeds a preset threshold θth (for example, θth = 65%). As a result, switching to the multi-speed mode is determined.

  In this case, in order to realize a suitable acceleration feeling due to the shift to the multi-stage shift mode, it is desirable to accompany an increase in the primary rotational speed (engine speed) at the time of the transition. For this reason, in the TCU 21, in addition to the determination condition of the accelerator opening θacc described above, the target primary rotation speed Npt_s calculated from the shift speed at the time of shifting to the multi-speed shift mode is the target primary speed set in the continuously variable shift mode. Higher than the rotational speed Npt_n is set as a further determination condition for the multi-speed mode. In other words, at the time of transition from the continuously variable transmission mode to the multi-speed transmission mode, a fixed transmission ratio on the lower speed side (that is, the transmission ratio is higher) than the transmission ratio set in the continuously variable transmission mode immediately before the transition is always set. The selection of the gear position to be set is set as a determination condition.

  By the way, in order to make the switching of the shift control mode at the time of acceleration or the like coincide with the feeling of the driver, in particular, it is determined that the shift from the continuously variable shift mode to the multi-speed shift mode is interlocked with the increase of the accelerator opening. It is desirable that Therefore, when the determination condition for the target primary rotational speed Npt is added as described above, the target primary rotational speed Npt_s in the multi-stage transmission mode is always set to the target in the continuously variable transmission mode before the accelerator opening θacc exceeds the threshold θth. It is necessary to exceed the primary rotational speed Npt_n.

  Here, for example, on the continuously variable transmission map shown in FIG. 5, the fixed speed ratio line of the third speed from the point where the speed change line of the accelerator opening θacc = θth (θacc = 65%) intersects the fixed speed ratio line of the second speed. The vehicle speed region up to the point where the vehicle intersects is defined as “region 1”. As is apparent from the figure, when the accelerator opening θacc exceeds the threshold θth in this region 1, the target primary rotational speed Npt_s exceeds the target primary rotational speed Npt_n unless the gear position in the multi-speed mode is 2 speed or less. Conversely, if the gear position in the multi-speed mode is greater than or equal to the third speed, the target primary rotation speed Npt_s will be lower than the target primary rotation speed Npt_n. Therefore, in the region 1, in order to make the target primary rotation speed Npt_s higher than the target primary rotation speed Npt_n, it is necessary to determine the downshift to the second gear or less before the accelerator opening θacc exceeds θth. There is. On the other hand, since each shift line in the multi-speed shift map is set based on the output characteristics of the engine 1 or the like, the above conditions are not always satisfied. Therefore, for example, as shown in FIG. 6, in the multi-speed mode map of the present embodiment, the 3-2 shift line for downshifting the shift speed from the third speed to the second speed is always equal to or less than the threshold θth in the region 1. It has been corrected to be located at. That is, in this embodiment, the 3-2 shift line for downshifting the gear stage from the third speed to the second speed is first set in a region after the basic shape is set based on the output characteristics of the engine 1 and the like. A portion exceeding the threshold θth in 1 is corrected so as to be lower than the threshold θth. In FIG. 6, the 3-2 shift line before correction is indicated by a one-dot chain line, and the switching determination timing corresponding to the 3-2 shift line or the like is indicated by a two-dot chain line. Further, although not described, the vehicle speed region of “region 2” where the target primary rotational speed Npt_s does not exceed the target primary rotational speed Npt_n unless the shift speed in the multi-speed mode is 3 speed or less. (Each vehicle speed region, etc.), the same correction is performed for each corresponding shift line.

  As a result of such correction, the continuously variable transmission map has the speed ratio currently controlled in the continuously variable transmission mode as the speed after the shift to the multi-speed transmission mode before the accelerator opening θacc becomes larger than the threshold θth. It is set to select a gear having a fixed gear ratio on the lower speed side. Therefore, the TCU 21 can uniformly determine the switching of the shift control mode from the continuously variable transmission mode with a downshift to the multi-speed transmission mode at the same time as the accelerator opening θacc exceeds the threshold θth.

  In the case where the shift line is not corrected, there is an operation region in which switching of the shift control mode from the continuously variable transmission mode to the multi-speed transmission mode is not determined at the same time as the accelerator opening θacc exceeds the threshold θth. . For example, in the pre-correction 3-2 shift line indicated by the alternate long and short dash line in FIG. 6, in the driving range where the vehicle speed is 30 Km / h or more, the accelerator opening θacc is less than 65% and the second speed is determined. There is no. Accordingly, even if the accelerator opening degree θacc exceeds the threshold value θth due to the driver's depression of the accelerator pedal, the TCU 21 remains in the continuously variable transmission mode until it determines to downshift to the second speed. (See the two-dot chain line in FIG. 6). On the other hand, when the multi-stage transmission mode is selected, the TCU 21 determines to switch to the continuously variable transmission mode on the condition that the accelerator opening θacc is equal to or less than the threshold θth.

  In this case, when the shift from the multi-stage transmission mode to the continuously variable transmission mode is performed, if the difference between the target primary rotational speed Npt_s and the target primary rotational speed Npt_n is too large, the primary rotational speed Np varies significantly. Therefore, in order to reduce the sense of incongruity due to such large fluctuations in the primary rotational speed Np, the shift to the continuously variable transmission mode is performed when the target primary rotational speed Npt_s in the multi-speed transmission mode is higher than the target primary rotational speed in the continuously variable transmission mode. It is desirable to carry out after being upshifted to the high-speed stage as much as possible, assuming that it is high. On the other hand, in general, in the multi-speed mode, a new speed after the shift is maintained for a certain time or more (a preset delay time Δt or more) for the purpose of providing a moderation feeling at the time of shifting. However, for example, if the difference between the target primary rotational speed Npt_s at the gear stage newly selected by the upshift and the target primary rotational speed Npt_n at the continuously variable transmission mode is too small, the accelerator pedal is stepped on by the driver during the delay control. In such a case, the target primary rotation speed Npt_n may exceed the target primary rotation speed Npt_s. When the switching determination to the continuously variable transmission mode is performed in such a state where the target primary rotational speed Npt_n exceeds the target primary rotational speed Npt_s, the transition from the multi-speed transmission mode to the continuously variable transmission mode is The transition is accompanied by an increase in the rotational speed Np (that is, the engine rotational speed), which may cause the driver to feel uncomfortable. Accordingly, in the TCU 21, the upshift determination to the high speed side gear stage is performed, and the target primary rotation speed Ntp_s calculated from the fixed gear ratio of the gear stage (γ + 1) selected by the upshift determination is the delay. It is set as a further determination condition that the target primary rotational speed Ntp_n (Δt) max, which can be set in the continuously variable transmission mode after the time Δt has elapsed, falls below (for example, see FIG. 10).

  In the present embodiment, specifically, such a determination is selected by the upshift determination, for example, when an upshift determination to a shift stage (γ + 1) higher than the current shift stage γ is performed. The target primary speed Npt_s (γ + 2) calculated from the fixed speed ratio of the speed stage (γ + 2) one speed higher than the speed stage (γ + 1) to be set is the target primary speed Npt_n set in the continuously variable speed mode. This is performed depending on whether or not the value is smaller than a value obtained by adding a predetermined differential rotation threshold value β to (see, for example, FIGS.

  Here, the differential rotation threshold value β of the present embodiment is a variable value using the vehicle speed V and the accelerator opening degree θacc as parameters. For example, as shown in FIG. 9, the differential rotation threshold value β is determined based on the vehicle speed V and the vehicle speed V and the vehicle speed V and It is set for each accelerator opening θacc, mapped, and stored in the TCU 21. Then, by setting this differential rotation threshold value β to an appropriate value, the target primary rotation speed Npt_s (γ + 2) at the gear position (γ + 2) is continuously variable during the upshift process that is sequentially performed with the release of the accelerator pedal. When the target primary rotational speed Npt_n + β in the speed change mode falls below the target primary speed Npt_n + β for the first time, the target primary rotational speed Npt_s (γ) in the multi-stage speed change mode is more than a predetermined difference from the target primary speed Npt_n in the continuously variable speed mode. It is possible to determine that it is the highest gear stage having (at least a differential rotation greater than or equal to the maximum change amount of the target primary rotation speed Npt_n that can be assumed during the delay time).

Next, the shift control mode switching control executed by the TCU 21 will be described with reference to the shift control mode switching control routine shown in FIG. This routine is repeatedly executed every set time. When the routine is started, the TCU 21 first checks in step S101 whether the currently selected shift control mode is the continuously variable transmission mode. When the TCU 21 determines in step S101 that the currently selected shift control mode is the continuously variable transmission mode, the TCU 21 proceeds to step S102, and the currently selected shift control mode is not the continuously variable transmission mode (that is, If it is determined that the multi-speed mode is selected, the process proceeds to step S106.

  When the process proceeds from step S101 to step S102, the TCU 21 checks whether or not the current accelerator opening degree θacc is larger than a preset threshold value θth (for example, θth = 65%).

  If it is determined in step S102 that the current accelerator opening θacc is equal to or smaller than the threshold θth, the TCU 21 proceeds to step S105.

  On the other hand, when it is determined in step S102 that the current accelerator opening degree θacc is larger than the threshold value θth, the TCU 21 proceeds to step S103, and the target primary rotational speed Npt_s (γ) calculated at the current gear stage γ is not present. It is checked whether it is smaller than the target primary rotational speed Npt_n in the step-shift mode.

  If it is determined in step S103 that the target primary rotational speed Npt_s (γ) is smaller than the target primary rotational speed, the TCU 21 proceeds to step S104 and switches the shift control mode from the continuously variable transmission mode to the multi-speed transmission mode. After judging the effect, the routine is exited.

  On the other hand, if it is determined in step S103 that the target primary rotation speed Npt_s (γ) is equal to or greater than the target primary rotation speed Npt_n, the TCU 21 proceeds to step S105.

  Then, when the process proceeds from step S102 or step S103 to step S105, the TCU 21 determines that the continuously variable transmission mode currently selected as the shift control mode is maintained, and then exits the routine.

  As described above with reference to FIG. 6 and the like, in the present embodiment, since the shift line for downshift determination is corrected, it is determined in step S102 that the accelerator opening θacc is higher than the threshold θth. In any case, it is always determined in step S103 that the target primary rotational speed Npt_s (γ) in the multi-stage transmission mode is less than the target primary rotational speed Npt_n in the continuously variable transmission mode. Accordingly, the determination in step S103 described above can be omitted as appropriate. Further, when the accelerator opening degree θacc exceeds the threshold value θth, the mode is always switched to the multi-stage shift mode. For example, as shown in FIG. It can be omitted as appropriate.

  When the process proceeds from step S101 to step S106, the TCU 21 checks whether or not the current accelerator opening degree θacc is equal to or smaller than the threshold value θth.

  If it is determined in step S106 that the current accelerator opening degree θacc is larger than the threshold value θth, the TCU 21 proceeds to step S111.

  On the other hand, if it is determined in step S106 that the current accelerator opening degree θacc is equal to or smaller than the threshold value θth, the TCU 21 proceeds to step S107, and has it been determined that an upshift to the higher speed side than the current gear position has been made? Check for no.

  If it is determined in step S107 that upshifting has not been performed, the TCU 21 proceeds to step S111.

  On the other hand, if it is determined in step S107 that the upshift is to be performed, the TCU 21 proceeds to step S108, for example, referring to a map shown in FIG. 9, the difference according to the current vehicle speed V and the accelerator opening θacc. The rotation threshold β is calculated with interpolation calculation.

  Then, when the process proceeds from step S108 to step S109, the TCU 21 changes the target primary rotation speed Npt_s (γ + 2) at the second shift speed higher than the current shift speed γ to the target primary rotation speed Npt_n in the continuously variable transmission mode. It is checked whether or not the difference rotation threshold value β is smaller than the added value.

  Here, when the target primary rotation speed Npt_s (γ + 2) is equal to or greater than the addition value of the target primary rotation speed Npt_n and the differential rotation threshold value β, the target primary rotation speed Npt_s (γ) in the multi-speed mode is continuously variable. This is a case where there is still room for lowering the target primary rotational speed Npt_s by the upshift in the multi-speed transmission mode in order to shift to the continuously variable transmission mode without a sense of incongruity sufficiently larger than the target primary rotational speed Npt_n of the mode. On the other hand, when the target primary rotation speed Npt_s (γ + 2) is changed to a value smaller than the addition value of the target primary rotation speed Npt_n and the differential rotation threshold value β, the target time at the delay time Δt after the upshift to the next stage is reached. Considering the possibility of an increase in the primary rotational speed Npt_n, it is not preferable to lower the target primary rotational speed Npt_s by further upshifting. As described above, such a determination can be suitably made by setting the differential rotation threshold value β to an appropriate value.

  In Step S109, when it is determined that the target primary rotation speed Npt_s (γ + 2) is smaller than the value obtained by adding the differential rotation threshold value β to the target primary rotation speed Npt_n, the TCU 21 proceeds to Step S110 and sets the shift control mode. After determining to switch from the multi-speed mode to the continuously variable mode, the routine is exited.

  On the other hand, if it is determined in step S109 that the target primary rotation speed Npt_s (γ + 2) is equal to or greater than the value obtained by adding the differential rotation threshold β to the target primary rotation speed Npt_n, the TCU 21 proceeds to step S111.

  When the process proceeds from step S106, step S107, or step S109 to step S111, the TCU 21 determines that the currently selected multi-stage shift mode is maintained as the shift control mode, and then exits the routine.

  According to such an embodiment, the mode of shift control to be performed on the continuously variable transmission 3 is selected between the continuously variable transmission mode and the multi-speed transmission mode based on the operating state parameters including the accelerator opening θacc. By switching automatically, switching between the continuously variable transmission mode and the multi-speed transmission mode can be realized at a timing without a sense of incongruity without depending on a shift operation or the like.

  In this case, when the continuously variable transmission mode is executed, the accelerator opening θacc is larger than the threshold value θth, and the target primary rotational speed Npt_n is calculated from the speed selected in the multi-speed mode. By switching to the multi-stage transmission mode on condition that it is greater than Npt_s, the mode is shifted to the multi-stage transmission mode with a downshift to a lower speed stage than the transmission ratio in the continuously variable transmission mode. Thus, the shift control mode can be switched in accordance with the feeling of the driver. Furthermore, for the downshift characteristics in the multi-speed mode, select a gear stage having a fixed gear ratio on the lower speed side than the gear ratio controlled in the continuously variable transmission mode before the accelerator opening θacc becomes larger than the threshold value θth. With this setting, when the accelerator opening θacc exceeds the threshold θth, it is possible to promptly determine whether to switch the shift control mode from the continuously variable transmission mode to the multi-speed transmission mode, and to improve the driver's performance. Switching of the shift control mode that matches the ring can be realized.

  In addition, when the multi-stage shift mode is executed, the accelerator opening becomes equal to or smaller than the set value, the upshift determination to the shift stage on the higher speed side than the current shift stage γ is performed, and the shift selected by the upshift determination is performed. The target primary rotational speed Npt_s (γ + 1) calculated from the fixed speed ratio of the stage (γ + 1) is the maximum target primary rotational speed Ntp_n (Δt) that can be set in the continuously variable transmission mode after a preset delay time Δt has elapsed. ) When it is determined that it is lower than max, it is possible to realize the switching of the shift control mode that matches the feeling of the driver by determining the switching of the shift control mode.

  That is, for example, as shown in FIG. 10, when the current shift stage is γ and an upshift to the shift stage (γ + 1) is determined at timing T, the setting is made based on the vehicle characteristics after the delay time Δt. When it is determined that the maximum target primary rotational speed Npt_n (Δt) max that can be exceeded exceeds the target primary rotational speed Npt_s (γ + 1) at the shift speed (γ + 1), an upshift to the shift speed (γ + 1) is performed. By determining whether or not to switch to the continuously variable transmission mode, the shift to the upshift side accompanying the release of the accelerator pedal of the driver is allowed as much as possible before switching to the multi-speed transmission mode. An increase in the primary rotational speed Npt at the time of switching to the step shift mode can be accurately prevented.

  In addition, this invention is not limited to each embodiment described above, A various deformation | transformation and change are possible, and they are also in the technical scope of this invention. For example, in the above-described embodiment, an example in which the threshold value θth is set to a constant value (for example, 65%) has been described. However, the present invention is not limited to this, and for example, the threshold value θth in the low vehicle speed region. It is also possible to set a different value depending on the vehicle speed region so that is relatively smaller than the threshold value θth of the high vehicle speed region.

  In the above-described embodiment, the threshold value θth for determining the switching from the multi-speed mode to the continuously variable speed mode and the threshold value θth for determining the switching from the continuously variable speed mode to the multi-speed mode are described. However, for example, the threshold value θth for determining the switching from the multi-speed mode to the continuously variable mode is set to the threshold value θth for determining the switching from the multi-speed mode to the continuously variable mode. It is also possible to set a relatively small value. Further, the determination of switching from the multi-speed mode to the continuously variable mode substantially includes the determination of whether or not the accelerator opening θacc is less than or equal to the threshold θth by a determination based on the differential rotation threshold β. Therefore, the determination based on the threshold value θth can be omitted as appropriate.

DESCRIPTION OF SYMBOLS 1 ... Engine 1a ... Crankshaft 2 ... Torque converter 3 ... Continuously variable transmission 4 ... Output shaft 5 ... Intake passage 6a ... Throttle valve 7 ... Throttle actuator 9 ... Forward / reverse switching device 10 ... Primary shaft 11 ... Secondary shaft 15 ... Primary Pulley 15a ... fixed pulley 15b ... movable pulley 15c ... primary hydraulic chamber 16 ... secondary pulley 16a ... fixed pulley 16b ... movable pulley 16c ... secondary hydraulic chamber 17 ... chain 20 ... engine control unit 21 ... transmission control unit (continuously variable transmission means, Multi-speed transmission means, mode switching means)
25 ... Engine speed sensor 26 ... Accelerator opening sensor 27 ... Vehicle speed sensor 28 ... Primary speed sensor 29 ... Secondary speed sensor

Claims (3)

A transmission control device for a continuously variable transmission that transmits the rotation of an input-side rotator driven by an engine to an output-side rotator by steplessly changing a gear ratio via a power transmission element,
Continuously variable transmission means for continuously controlling the speed ratio based on a preset continuously variable transmission characteristic;
Multi-stage transmission means for selecting a shift stage based on a multi-stage transmission characteristic having a preset multi-stage upshift characteristic and downshift characteristic and controlling the transmission ratio to a fixed transmission ratio of the selected shift stage;
Based on the parameters of operating conditions including accelerator opening, wherein the mode shift control to be executed for a continuously variable transmission, the multi-speed mode by the stepless speed change mode and the multi-speed unit by the continuously variable transmission Mode switching means for selectively switching between,
Said mode switching means, during the execution of the multi-speed mode, the result that the accelerator opening degree is less than the set threshold value, the upshift decision to the gear of the high speed side is performed, and the selected by the upshift determination The maximum value of the target rotational speed of the input-side rotator that the rotational speed of the input-side rotator calculated from the fixed speed ratio of the gear stage can be set in the continuously variable transmission mode after a preset delay time has elapsed. A shift control device for a continuously variable transmission, wherein when it is determined that the speed is lower than the threshold value, switching from the multi-speed mode to the continuously variable mode is determined. The mode switching means, the accelerator opening becomes less than the set threshold value, during execution of the multi-speed mode, upshift determination to the gear of the high speed side is performed, and the selected by the upshift determination The rotational speed of the input-side rotator calculated from the fixed speed ratio of the shift stage that is one speed higher than the shift speed is set to the target rotational speed of the input-side rotator that is set in the continuously variable transmission mode. The continuously variable transmission according to claim 1, wherein when it is determined that the value is smaller than a value obtained by adding a preset differential rotation threshold value, switching from the multi-speed mode to the continuously variable mode is determined. Shift control device. The differential speed threshold, the shift control device for a continuously variable transmission according to claim 2, wherein the a value is variably set according to the accelerator opening and the vehicle speed.

Images