JP2013167349A - Vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress gear shift shocks when changing a transmission gear ratio of a continuously variable transmission to increase an input shaft rotational speed of the continuously variable transmission by a predetermined amount, in a vehicle including the continuously variable transmission.SOLUTION: In a vehicle including a continuously variable transmission, an ECU sets, when a timing is a step-down gear shift start timing for increasing an input shaft rotational speed NIN of the continuously variable transmission by a predetermined amount (YES in step S10), an increase speed of a target input rotational speed NINtag according to the input shaft rotational speed NIN and an output shaft rotational speed NOUT so that the increased speed of a gear change ratio γ during the step-down gear shifting can be less than a permitted speed (S11). The ECU then increases the target input shaft rotational speed NINtag at the set increase speed (S12).

Description

  The present invention relates to a vehicle including a continuously variable transmission.

  Japanese Patent Laying-Open No. 2004-125072 (Patent Document 1) discloses that in a vehicle equipped with a continuously variable transmission, the input shaft rotational speed of the continuously variable transmission is increased by a predetermined rotational speed increase when a user requests acceleration. A technique for performing time downshift control is disclosed.

JP 2004-125072 A JP 2009-280133 A

  However, as in Patent Document 1, if the input shaft speed of the continuously variable transmission is increased by a predetermined speed increase amount by the shift down control during acceleration, a large inertia torque is generated depending on the state of the vehicle. There is a risk of becoming.

  The present invention has been made in order to solve the above-described problems, and an object thereof is not to increase the input shaft rotational speed of the continuously variable transmission by a predetermined amount in a vehicle including the continuously variable transmission. When changing the gear ratio of the step transmission, the shift shock is suppressed.

  A vehicle according to the present invention includes an engine, drive wheels, a continuously variable transmission provided between the engine and the drive wheels, and an input shaft rotational speed of the continuously variable transmission is increased by a predetermined amount in response to a user's acceleration request. And a control device that performs step shifting to change the gear ratio of the continuously variable transmission. The control device changes the increasing speed of the input shaft rotation speed at the step shift according to the change amount of the gear ratio at the step shift.

  Preferably, the control device decreases the increase speed of the input shaft rotation speed at the time of the step shift as the change amount of the gear ratio at the time of the step shift is larger.

  Preferably, the amount of change in the gear ratio during the step shift increases as the vehicle speed decreases. The control device decreases the increase speed of the input shaft rotation speed at the time of step shift as the vehicle speed is lower.

  Preferably, the amount of change in the gear ratio during the step shift increases as the input shaft rotation speed decreases. The control device decreases the increase speed of the input shaft rotation speed at the time of step shifting as the input shaft rotation speed is lower.

  Preferably, the control device adjusts the increase speed of the input shaft rotation speed at the step shift so that the change speed of the speed ratio at the step shift does not exceed the allowable speed.

  Preferably, the control device performs a step shift every time the actual accelerator opening increases by a predetermined value.

  According to the present invention, in a vehicle equipped with a continuously variable transmission, the shift shock is suppressed when the transmission ratio of the continuously variable transmission is changed so as to increase the input shaft rotational speed of the continuously variable transmission by a predetermined amount. be able to.

It is a figure which shows schematic structure of a vehicle. It is a control block diagram which shows the equipment connected to ECU and ECU. It is a functional block diagram of ECU. FIG. 6 is a diagram illustrating waveforms of an actual accelerator opening A, a shift control accelerator opening Asft, and a target input shaft speed NINtag. It is the figure which showed typically the waveform of the inertia torque which arises when gear ratio γ is increased. FIG. 6 is a diagram (No. 1) schematically showing changes in a target input shaft speed NINtag and a gear ratio γ when a step-down shift is performed. FIG. 6 is a diagram (No. 2) schematically showing changes in a target input shaft speed NINtag and a gear ratio γ when a step-down shift is performed. It is a flowchart which shows the process sequence of ECU.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a diagram showing a schematic configuration of a vehicle 1 according to the present embodiment. The vehicle 1 travels by transmitting the power of the engine 200 to the drive wheels 800. On the power transmission path from the engine 200 to the drive wheel 800, a torque converter 300 with a lock-up clutch 308, a forward / reverse clutch 400, a belt-type continuously variable transmission 500, a reduction gear 600, and a differential gear device 700 are provided. It is done.

  The output of engine 200 is input to continuously variable transmission 500 via torque converter 300 and forward / reverse clutch 400. The output of the continuously variable transmission 500 is transmitted to the reduction gear 600 and the differential gear device 700, and is distributed to the left and right drive wheels 800. Instead of the belt type continuously variable transmission 500, a chain type or toroidal type continuously variable transmission may be used.

  The torque converter 300 includes a pump impeller 302 connected to the crankshaft of the engine 200, a turbine impeller 306 connected to the forward / reverse clutch 400 via the turbine shaft 304, and the pump impeller 302 and the turbine impeller 306. And a lockup clutch 308 provided therebetween.

  The lockup clutch 308 is engaged or released according to the hydraulic pressure supplied from the outside. When the lockup clutch 308 is engaged, the pump impeller 302 and the turbine impeller 306 rotate integrally. The pump impeller 302 is provided with a mechanical oil pump 310 that generates hydraulic pressure.

  The forward / reverse clutch 400 is a power transmission clutch provided between the torque converter 300 and the continuously variable transmission 500. The forward / reverse clutch 400 is composed of a double pinion type planetary gear device. Turbine shaft 304 of torque converter 300 is connected to sun gear 402. The input shaft 502 of the continuously variable transmission 500 is connected to the carrier 404. Carrier 404 and sun gear 402 are connected via forward clutch 406. Ring gear 408 is fixed to the housing via reverse brake 410. The forward clutch 406 and the reverse brake 410 are engaged or released by hydraulic pressure supplied from outside.

  When the forward clutch 406 is engaged and the reverse brake 410 is released, the forward / reverse clutch 400 enters a forward power transmission state in which the forward drive force is transmitted to the continuously variable transmission 500. When the forward clutch 406 is disengaged and the reverse brake 410 is engaged, the forward / reverse clutch 400 enters a reverse power transmission state in which driving force in the reverse direction is transmitted to the continuously variable transmission 500. When the forward clutch 406 is released, the forward / reverse clutch 400 enters a neutral state in which power transmission is interrupted.

  The continuously variable transmission 500 includes a primary pulley 504 provided on the input shaft 502, a secondary pulley 508 provided on the output shaft 506, and a transmission belt 510 wound around these pulleys. Power is transmitted using frictional forces between the pulleys and the transmission belt 510.

  By controlling the hydraulic pressure of the hydraulic cylinder of the primary pulley 504, the groove width of each pulley changes. As a result, the engagement diameter of the transmission belt 510 is changed, and the gear ratio γ (= input shaft rotational speed NIN / output shaft rotational speed NOUT) is continuously changed.

  FIG. 2 is a control block diagram showing an ECU (Electronic Control Unit) 8000 that controls each device of the vehicle 1 and devices connected to the ECU 8000.

  As shown in FIG. 2, the ECU 8000 includes an engine speed sensor 902, a turbine speed sensor 904, a vehicle speed sensor 906, a throttle opening sensor 908, a cooling water temperature sensor 910, an oil temperature sensor 912, an accelerator opening sensor 914, a foot A brake switch 916, a position sensor 918, a primary pulley rotation speed sensor 922, and a secondary pulley rotation speed sensor 924 are connected.

  Engine speed sensor 902 detects the rotational speed of engine 200 (hereinafter referred to as “engine speed NE”). The turbine rotation speed sensor 904 detects the rotation speed of the turbine shaft 304 (hereinafter referred to as “turbine rotation speed NT”). The vehicle speed sensor 906 detects the vehicle speed V. The throttle opening sensor 908 detects the opening degree θ (TH) of the electronic throttle valve. Cooling water temperature sensor 910 detects cooling water temperature T (W) of engine 200. The oil temperature sensor 912 detects the oil temperature T (C) of the continuously variable transmission 500 or the like. The accelerator opening sensor 914 detects an accelerator opening (amount of operation of the accelerator pedal by the user) A. The foot brake switch 916 detects whether or not the foot brake is operated. The position sensor 918 detects the position P (SH) of the shift lever 920 operated by the user. Primary pulley rotation speed sensor 922 detects the rotation speed of primary pulley 504 (hereinafter referred to as “input shaft rotation speed NIN”). Secondary pulley rotation speed sensor 924 detects the rotation speed of secondary pulley 508 (hereinafter referred to as “output shaft rotation speed NOUT”). When the forward / reverse clutch 400 is in the forward power transmission state, the turbine rotational speed NT coincides with the input shaft rotational speed NIN. The vehicle speed V becomes a value corresponding to the output shaft rotational speed NOUT. Therefore, when the vehicle is stopped and the forward clutch 406 is engaged, the turbine speed NT is zero. Each sensor transmits a signal representing the detection result to ECU 8000.

  ECU 8000 controls output of engine 200 by controlling electronic throttle valve 1000, fuel injection device 1100, ignition device 1200, and the like. ECU 8000 executes engagement control of lockup clutch 308 and forward / reverse clutch 400, shift control of continuously variable transmission 500, and the like by controlling hydraulic control circuit 2000.

  FIG. 3 is a functional block diagram of the ECU 8000 relating to throttle control and shift control. Each functional block shown in FIG. 3 may be realized by hardware or software.

  ECU 8000 includes a setting unit 8010, a throttle control unit 8011, setting units 8020 and 8021, and a shift control unit 8022.

  The setting unit 8010 uses an accelerator opening A (hereinafter referred to as “actual accelerator opening A”) detected by the accelerator opening sensor 914 to use an accelerator opening (hereinafter referred to as “throttle control accelerator opening Ath”) for throttle control. ”). The setting unit 8010 sets the actual accelerator opening A as it is to the throttle control accelerator opening Ath. Accordingly, the throttle opening Ath for throttle control changes in the same manner as the actual accelerator opening A.

  The throttle control unit 8011 controls the electronic throttle valve 1000 so that the opening degree of the electronic throttle valve 1000 (hereinafter referred to as “throttle opening θ”) becomes an opening degree corresponding to the throttle control accelerator opening degree Ath. As a result, the throttle opening θ is increased according to the accelerator pedal depression amount by the user.

  On the other hand, setting unit 8020 uses actual accelerator opening A to set an accelerator opening used for shift control (hereinafter referred to as “shift control accelerator opening Asft”). In other words, in the present embodiment, throttle control accelerator opening Ath and shift control accelerator opening Asft are set separately. The setting unit 8020 does not set the actual accelerator opening A as it is to the shift control accelerator opening Asft, but provides a dead zone (hysteresis) each time the shift control accelerator opening Asft is updated. The shift control accelerator opening Asft is changed stepwise. More specifically, the setting unit 8020 corresponds the shift control accelerator opening Asft to the actual accelerator opening A every time the difference between the actual accelerator opening A and the shift control accelerator opening Asft exceeds a predetermined amount. When the difference does not exceed the predetermined value, even if the actual accelerator opening A increases or decreases, the shift control accelerator opening Asft is maintained at the value at the previous update.

  Setting unit 8021 sets a target value for input shaft rotational speed NIN (hereinafter referred to as “target input shaft rotational speed NINtag”) using shift control accelerator pedal opening Asft and output shaft rotational speed NOUT. The setting unit 8021 sets the target input shaft speed NINtag to a larger value as the shift control accelerator opening Asft is larger.

  FIG. 4 is a diagram illustrating waveforms of the actual accelerator opening A, the shift control accelerator opening Asft, and the target input shaft rotational speed NINtag. FIG. 4 shows a case where the vehicle speed V (output shaft rotational speed NOUT) is constant.

  With reference to FIG. 4, a method for setting shift control accelerator pedal opening Asft by setting unit 8020 will be described.

It is assumed that the shift control accelerator opening Asft is updated at time t0. After time t0, the actual accelerator opening A has increased, but the increase amount (= A−Asft) of the actual accelerator opening A with respect to the shift control accelerator opening Asft is less than a predetermined value α (α> 0). During this time, the accelerator opening Asft for shift control is maintained at the value of the previous time (time t0). Then, at the time t1 when the increase amount (= A−Asft) of the actual accelerator opening A reaches the predetermined value α, the shift control accelerator opening Asft is increased stepwise by the predetermined value α, and the actual accelerator opening. Updated to a value corresponding to A. In response to the shift control accelerator opening Asft is increased by stepwise predetermined value alpha, the target input shaft rotational speed NINtag also increased by a predetermined amount N _alpha only stepwise.

Similarly, after time t1, the shift control accelerator opening Asft is not updated while the actual accelerator opening A increase amount (= A−Asft) is less than the predetermined value α, and the actual accelerator opening A increases. The amount (= A−Asft) is increased stepwise by the predetermined value α at time t2 when the predetermined value α is reached. Accordingly, the target input shaft rotational speed NINtag also increased by a predetermined amount N _alpha only stepwise.

  Also, when the actual accelerator opening A decreases, the shift control accelerator opening Asft is decreased stepwise by a basically similar method. Specifically, while the reduction amount (= Asft−A) of the actual accelerator opening A with respect to the shift control accelerator opening Asft is less than a predetermined value β (β> 0), the shift control accelerator opening Asft is the previous time. When the reduction amount of the actual accelerator opening A (= Asft−A) reaches the predetermined value β, the shift control accelerator opening Asft is decreased stepwise by the predetermined value β. In the example shown in FIG. 4, the actual accelerator opening A decreases for a while from the time t2, but the reduction amount (= Asft-A) of the actual accelerator opening A with respect to the shift control accelerator opening Asft is predetermined. Since it is less than the value β, the shift control accelerator opening Asft is not updated.

  Thus, in the present embodiment, the shift control accelerator opening Asft is changed stepwise with respect to the change in the actual accelerator opening A. Therefore, the target input shaft rotational speed NINtag is also changed stepwise. As a result, the gear ratio γ (= NIN / NOUT) also changes stepwise. Hereinafter, such shift control is also referred to as “step shift control”, and a down shift that increases the gear ratio γ of the continuously variable transmission 500 stepwise by the step shift control is also referred to as “step down shift”.

  In the vehicle 1 having the above-described configuration, when the above-described step-down shift is performed, an inertia torque in the negative direction (deceleration direction) is generated in the continuously variable transmission 500, which may cause the user to feel a shift shock. There is sex.

  FIG. 5 is a diagram schematically showing an inertia torque waveform generated when the speed ratio γ is increased stepwise by a predetermined amount during the step-down shift.

  When the gear ratio γ is increased stepwise, a negative inertia torque occurs, but the inertia torque increases as the speed of increase of the gear ratio γ increases. That is, as shown in FIG. 5, when the increase speed of the gear ratio γ is r1, r2, r3 (r1> r2> r3), the magnitudes (absolute values) of the inertia torque are T1, T2, and T3, respectively. , T1> T2> T3 is established.

  Therefore, in order to suppress the inertia torque generated at the time of step-down shift to an allowable level (a level at which the user does not feel a shift shock), the speed of increase of the gear ratio γ exceeds the allowable speed (the upper limit speed at which the user does not feel a shift shock). It is desirable to suppress it.

During step-down gear, thus increasing the target input shaft rotational speed NINtag a predetermined amount N _alpha only stepwise. However, even when increasing the target input shaft rotational speed NINtag predetermined amount N _alpha, as the vehicle speed V (output shaft rotation speed NOUT) is low, it tends to increase the gear ratio γ increases. Also, the same if the target input shaft rotational speed NINtag increased to a predetermined amount N _alpha only stepwise in the gear ratio gamma tends to the input shaft rotation speed NIN becomes large increase in low that the speed ratio gamma. Therefore, if the increase speed of the target input shaft speed NINtag at the time of the step-down shift is made constant, the increase speed of the speed ratio γ increases as the vehicle speed V decreases and the input shaft speed NIN decreases. May be exceeded.

  Therefore, ECU 8000 (setting unit 8021 described in FIG. 3) according to the present embodiment increases the increase speed of target input shaft speed NINtag so that the increase speed of gear ratio γ does not exceed the allowable speed at the time of step-down shift. adjust. Specifically, ECU 8000 decreases the increase speed of target input shaft speed NINtag as the increase amount of gear ratio γ increases (that is, as vehicle speed V is lower and input shaft speed NIN is lower). This is the most characteristic point of the present embodiment.

  FIG. 6 is a diagram schematically showing changes in the target input shaft speed NINtag and the gear ratio γ when a step-down shift is performed when the input shaft speed NIN is a predetermined value N1. In FIG. 6, “a”, “b”, and “c” indicate waveforms when the output shaft rotation speed NOUT at the start of the step-down shift is Na, Nb, and Nc (Na <Nb <Nc), respectively. .

  FIG. 6A shows changes in operating points of the input shaft rotational speed NIN and the output shaft rotational speed NOUT. In FIG. 6A, the horizontal axis represents the output shaft rotational speed NOUT, and the vertical axis represents the input shaft rotational speed NIN. Therefore, the speed ratio γ corresponds to the slope of the straight line passing through the origin (= NIN / NOUT), and the increase amount of the speed ratio γ corresponds to the increase amount of the slope. Note that the speed changeable range (changeable range of the speed ratio γ) is limited to a range from the lower limit speed ratio γmin to the upper limit speed ratio γmax due to hardware limitations of the continuously variable transmission 500.

Also the input shaft rotational speed NIN in the case of increasing by the same predetermined amount N _alpha from a predetermined value N1, as the vehicle speed V is low, the speed ratio γ becomes the Low side, the increase of the speed ratio γ increases.

Referring to the example shown in FIG. 6, the amount of increase in γ when NIN = N1 is (N1 + N _α ) / NOUT−N1 / NOUT = N _α / NOUT. Therefore, when NOUT = Na, Nb, and Nc, the γ increases are N _α / Na, N _α / Nb, and N _α / Nc, respectively, but since Na <Nb <Nc, N _α / Na> N The relationship of _α / Nb> N _α / Nc is established.

  Considering this point, when performing the step-down shift, the ECU 8000 slows the increase speed of the target input shaft speed NINtag as the vehicle speed V is lower, as shown in FIG. 6B. As a result, regardless of the vehicle speed V, the increasing speed of the speed ratio γ can be adjusted to a value less than the allowable speed. Therefore, the inertia torque generated at the time of the step-down shift can be reduced and the shock given to the user can be suppressed. Note that the example shown in FIG. 6B shows a case where the increasing speed (gradient) of the gear ratio γ is adjusted to a constant value less than the allowable speed, regardless of whether NOUT = Na, Nb, or Nc. Has been.

  FIG. 7 is a diagram schematically showing changes in the target input shaft speed NINtag and the speed ratio γ when a step-down speed change is performed when the speed ratio γ is the predetermined ratio γ1. In FIG. 7, “d”, “e”, and “f” indicate waveforms when the input shaft rotational speed NIN at the start of the step-down shift is Nd, Ne, and Nf (Nd <Ne <Nf), respectively. .

  FIG. 7A shows changes in operating points of the input shaft rotational speed NIN and the output shaft rotational speed NOUT, as in FIG. 6A. Therefore, the increase amount of the speed ratio γ corresponds to the increase amount of the slope of the straight line passing through the origin.

Even when increasing the input shaft speed NIN by the same predetermined amount N _alpha, when the speed ratio γ is the same predetermined ratio γ1 is, the lower the input shaft rotational speed NIN, the increase of the speed ratio γ is greater Become.

In the example shown in FIG. 7, when γ = γ1, the amount of increase in γ is (NIN + N _α ) / NOUT−NIN / NOUT = (NIN + N _α ) / (NIN / γ1) −NIN / (NIN / γ1) = N _α × γ1 / NIN. Therefore, when NIN = Nd, Ne, and Nf, γ increases are N _α × γ1 / Nd, N _α × γ1 / Ne, and N _α × γ1 / Nf, respectively, because Nd <Ne <Nf. The relationship N _α × γ1 / Nd> N _α × γ1 / Ne> N _α × γ1 / Nf is established.

  In consideration of this point, when performing the step-down shift, the ECU 8000 slows the increase rate of the target input shaft speed NINtag as the input shaft speed NIN is lower, as shown in FIG. 7B. Thereby, regardless of the level of the input shaft rotational speed NIN, the increasing speed of the gear ratio γ can be adjusted to a value less than the allowable speed (a constant value in the example shown in FIG. 7B). Therefore, the inertia torque generated at the time of the step-down shift can be reduced and the shock given to the user can be suppressed. Note that the example shown in FIG. 7B shows a case where the increasing speed (gradient) of the speed ratio γ is adjusted to a constant value less than the allowable speed in any case of NIN = Nd, Ne, and Nf. Has been.

  FIG. 8 is a flowchart showing a processing procedure of ECU 8000 for realizing the above-described function.

  At step (hereinafter, step is abbreviated as “S”) 10, ECU 8000 determines whether or not it is the start timing of the step-down shift (the update timing of shift control accelerator pedal opening Asft).

  When it is the start timing of the step-down shift (YES in S10), ECU 8000, in S11, the input shaft speed NIN and the output so that the increasing speed of the gear ratio γ at the step-down shift is less than the allowable speed. The increase speed of the target input shaft speed NINtag is set according to the shaft speed NOUT. For example, ECU 8000 maps and stores in advance the increase speed of target input shaft speed NINtag adjusted so that the increase speed of gear ratio γ is less than the allowable speed using NIN and NOUT as parameters, and this map is used. What is necessary is just to set the increase speed of the target input shaft rotational speed NINtag corresponding to actual NIN and NOUT.

  In step S12, the ECU 8000 increases the target input shaft rotational speed NINtag at the increasing speed set in step S11.

  As described above, ECU 8000 according to the present embodiment changes the increasing speed of input shaft rotation speed NIN at the time of step shifting so that the increasing speed of gear ratio γ does not exceed the allowable speed at the time of step-down shifting. Specifically, the ECU 8000 increases the increase speed of the target input shaft speed NINtag as the increase amount of the speed ratio γ during the step-down shift is larger (that is, as the vehicle speed V is lower and the input shaft speed NIN is lower). Reduce. Therefore, the inertia torque generated at the time of the step-down shift can be reduced and the shock given to the user can be suppressed.

  In this embodiment, the increase speed of the target input shaft speed NINtag is set according to NIN and NOUT, but the increase speed of the target input shaft speed NINtag is set according to either NIN or NOUT. You may do it.

  In the present embodiment, the target input shaft speed NINtag is increased by a predetermined amount Nα by increasing the shift control accelerator opening Asft stepwise by a predetermined value α, but the target input shaft speed NINtag The increase method is not limited to this, and other methods may be used.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 vehicle, 200 engine, 300 torque converter, 302 pump wheel, 304 turbine shaft, 306 turbine wheel, 308 lock-up clutch, 310 oil pump, 400 forward / reverse clutch, 402 sun gear, 404 carrier, 406 forward clutch, 408 ring gear , 410 reverse brake, 500 continuously variable transmission, 502 input shaft, 504 primary pulley, 506 output shaft, 508 secondary pulley, 510 transmission belt, 600 reduction gear, 700 differential gear device, 800 drive wheel, 902 engine speed sensor , 904 Turbine speed sensor, 906 Vehicle speed sensor, 908 Throttle opening sensor, 910 Cooling water temperature sensor, 912 sensor, 914 Accelerator opening sensor, 916 Foot brake switch H, 918 position sensor, 920 shift lever, 922 primary pulley rotation speed sensor, 924 secondary pulley rotation speed sensor, 1000 electronic throttle valve, 1100 fuel injection device, 1200 ignition device, 2000 hydraulic control circuit, 8000 ECU, 8010, 8020, 8021 Setting unit, 8011 Throttle control unit, 8022 Shift control unit.

Claims (6)

Engine,
Driving wheels,
A continuously variable transmission provided between the engine and the drive wheel;
A control device that performs step shifting to change the transmission ratio of the continuously variable transmission so as to increase the input shaft rotational speed of the continuously variable transmission by a predetermined amount in response to a user's acceleration request;
The control device changes the increasing speed of the input shaft rotation speed at the step shift according to the amount of change in the gear ratio at the step shift.   2. The vehicle according to claim 1, wherein the control device decreases an increase speed of the input shaft rotation speed at the step shift as the change amount of the speed ratio at the step shift is larger. The amount of change in the gear ratio during the step shift increases as the vehicle speed decreases,
The vehicle according to claim 2, wherein the control device decreases the increase speed of the input shaft rotation speed during the step shift as the vehicle speed is lower. The amount of change in the gear ratio during the step shift becomes larger as the input shaft rotational speed is lower,
4. The vehicle according to claim 2, wherein the control device decreases an increase speed of the input shaft rotation speed during the step shift as the input shaft rotation speed is lower. 5.   2. The vehicle according to claim 1, wherein the control device adjusts an increase speed of the input shaft rotation speed at the step shift so that a change speed of the speed ratio at the step shift does not exceed an allowable speed.   The vehicle according to claim 1, wherein the control device performs the step shift every time the actual accelerator opening increases by a predetermined value.

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