JP2018071680A - Controller of continuously variable transmission - Google Patents

Abstract

An object of the present invention is to provide a control device for a continuously variable transmission that can prevent an unnecessary engine brake from acting during an upshift, and can reduce a sense of incongruity given to a driver. A continuously variable transmission mechanism disposed between a motor generator and a drive wheel, and a CVT control for shifting the transmission ratio of the continuously variable transmission mechanism at a preset standard speed toward a target transmission ratio. A unit 81, and when the continuously variable transmission mechanism 4 is downshifted, the brake pedal 63 is depressed, and the actual transmission ratio of the continuously variable transmission mechanism 4 changes to the downshift side during a period after Of these, the downshift speed in at least a part of the period is set to a speed limit slower than the standard speed. [Selection] Figure 3

Description

  The present invention relates to a control device for a continuously variable transmission.

  2. Description of the Related Art Conventionally, a control device for a continuously variable transmission that regulates the speed of a continuously variable transmission mechanism based on depression of a brake pedal is known (see, for example, Patent Document 1).

JP 2007-255629 A

However, when the accelerator pedal is released from the acceleration state where the accelerator pedal is depressed and then the brake pedal is depressed for a short period of time, an unintended engine brake may act and give the driver a sense of incongruity. .
That is, when the accelerator pedal is released, the target gear ratio in the continuously variable transmission mechanism is upshifted toward the highest gear ratio or the ultimate target gear ratio during coasting (coast gear line). Then, as the vehicle speed decreases, the vehicle shifts down along the coast shift line. However, if the brake pedal is depressed within a short time after the accelerator pedal is released, the brake pedal is depressed during the upshift. If the shift speed is restricted at this time, the upshift speed is restricted. As a result, the actual gear ratio during deceleration becomes a lower gear ratio than the highest gear ratio or coast gear ratio, resulting in the occurrence of unnecessary engine braking.

  An object of the present invention is to provide a control device for a continuously variable transmission that can prevent an unintended operation of an engine brake and reduce a feeling of strangeness given to a driver.

In order to achieve the above object, a continuously variable transmission control device according to the present invention includes a continuously variable transmission mechanism disposed between a driving source for driving and a drive wheel, and a gear ratio of the continuously variable transmission mechanism. Shift control means for shifting at a standard speed set in advance toward.
In the period after the condition that the brake pedal is depressed and the actual transmission ratio of the continuously variable transmission mechanism changes to the downshift side is established during the downshift of the continuously variable transmission mechanism. The downshift speed in at least a part of the period is set to a speed limit slower than the standard speed.

In the control device for a continuously variable transmission according to the present invention, even when the brake pedal is depressed within a short period of time after the accelerator pedal is released, the transmission speed during the upshift of the continuously variable transmission mechanism is the standard speed. After the actual gear ratio changes to the downshift side, the speed change speed becomes slower than the standard speed.
As a result, it is possible to prevent an unnecessary engine brake from acting during the upshift, and to reduce the uncomfortable feeling given to the driver.

1 is an overall system diagram showing a drive system and a control system of a hybrid vehicle to which a control device of Embodiment 1 is applied, and a hydraulic control system of a continuously variable transmission mechanism. It is an example of a shift diagram showing a shift schedule at the time of shift control executed by the CVT control unit of the first embodiment. 6 is a flowchart showing a flow of a shift speed control process executed by the CVT control unit of the first embodiment. In the control device for continuously variable transmission according to the first embodiment, the accelerator flag, the brake flag, the target transmission line, the target transmission ratio, the actual transmission ratio, the absolute value of the target primary stroke speed, the target primary stroke when the transmission speed control is performed. 4 is a time chart showing characteristics of position, vehicle speed, and vehicle G. It is explanatory drawing which shows the change of the actual gear ratio just before reaching the lowest gear ratio by the difference in gear speed.

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

Example 1
First, the configuration will be described.
The control device according to the first embodiment is applied to an FF hybrid vehicle having a parallel hybrid drive system with one motor and two clutches and having a transmission of a belt type continuously variable transmission. Hereinafter, the configuration of the first embodiment will be described by being divided into “overall system configuration”, “shift control configuration of continuously variable transmission mechanism”, and “shift speed control processing configuration”.

[Overall system configuration]
FIG. 1 shows a drive system and a control system of a hybrid vehicle to which the control device of the first embodiment is applied, and a hydraulic control system of a continuously variable transmission mechanism. The overall system configuration of the first embodiment will be described below with reference to FIG.

  The hybrid vehicle according to the first embodiment includes an engine 1 and a motor generator 2 as a driving source for traveling. The output rotation of the engine 1 or the motor generator 2 is transmitted to the drive wheels 6 through the forward / reverse switching mechanism 3, the continuously variable transmission mechanism 4, and the final reduction mechanism 5.

  The engine 1 is provided with an engine control actuator 10. The engine control actuator 10 operates the engine 1 with a desired torque based on a command from an engine control unit 84 described later, and rotates the engine output shaft 11. Between the engine 1 and the motor generator 2, the 1st clutch 12 which interrupts | rotates between them is provided.

  Motor generator 2 is driven by electric power output from inverter 21. The regenerative power of the motor generator 2 is input to the inverter 21. Inverter 21 operates motor generator 2 at a desired torque or a desired number of revolutions based on a command from motor control unit 83 to be described later. The motor generator 2 is constituted by a synchronous rotating electric machine driven by, for example, a three-phase alternating current. Inverter 21 is connected to battery 22.

  The forward / reverse switching mechanism 3 is provided between a traveling drive source including the engine 1 and the motor generator 2 and the continuously variable transmission mechanism 4. The forward / reverse switching mechanism 3 switches the rotation input from the motor output shaft 23 to the forward rotation direction (forward travel) or the reverse rotation direction (reverse travel), and inputs it to the continuously variable transmission mechanism 4. The forward / reverse switching mechanism 3 includes a double pinion planetary gear mechanism 30, a forward clutch 31, and a reverse brake 32, and when the reverse brake 32 is engaged in the forward rotation direction when the forward clutch 31 is engaged. Can be switched in the reverse direction.

  The planetary gear mechanism 30 includes a sun gear to which rotation of a drive source is input, a ring gear, and a carrier that supports the sun gear and a pinion gear that meshes with the ring gear. The forward clutch 31 is configured to be able to rotate the sun gear and the carrier integrally in the engaged state, and the reverse brake 32 is configured to be able to stop the rotation of the ring gear in the engaged state.

  In the forward / reverse switching mechanism 3, the reverse brake 32 is disposed on the outer peripheral side of the forward clutch 31. In the reverse brake 32, since one of the facing materials that come into contact with each other at the time of engagement is a non-rotating member such as a casing, the lubricating oil is smoothly supplied to and discharged from the facing surface as compared with the forward clutch 31 that is both a rotating member. It is hard to be done. That is, the reverse brake 32 is less likely to be sufficiently cooled by the lubricating oil than the forward clutch 31, and there is a risk that durability will be reduced due to heat generation. For this reason, the reverse brake 32 is disposed on the outer peripheral side of the forward clutch 31 in order to prevent a decrease in durability of the facing material, and is configured such that the surface area of the fading material is increased as compared with the forward clutch. The increase of is suppressed. For this reason, the reverse brake 32 is arranged on the outer peripheral side of the forward clutch 31, so that the reverse gear 32 can stop the rotation of the ring gear so that the ring gear arranged on the outer peripheral side is a fixed element. In order to obtain the rotation in the reverse direction in the state where the rotation is stopped, the double pinion type planetary gear mechanism 30 is provided. As a result, the speed reduction ratio during reverse travel is set larger than the speed reduction ratio during forward travel.

  One of the forward clutch 31 and the reverse brake 32 of the forward / reverse switching mechanism 3 is configured as a second clutch that intermittently rotates between the engine 1 and the motor generator 2 and the continuously variable transmission mechanism 4.

  The continuously variable transmission mechanism 4 is configured by a belt 44 being stretched between a primary pulley 42 and a secondary pulley 43, and the winding diameter of the belt 44 is increased by changing the groove width between the primary pulley 42 and the secondary pulley 43, respectively. This is a belt type continuously variable transmission that changes speeds.

  The primary pulley 42 includes a fixed pulley 42a and a movable pulley 42b. When the movable pulley 42b is moved by the primary hydraulic pressure supplied to the primary hydraulic chamber 45, the groove width of the primary pulley 42 is changed.

  The secondary pulley 43 includes a fixed pulley 43a and a movable pulley 43b. The movable pulley 43b is moved by the secondary hydraulic pressure supplied to the secondary hydraulic chamber 46, whereby the groove width of the secondary pulley 43 is changed.

  The belt 44 has a V-shaped sheave surface formed by a fixed pulley 42 a and a movable pulley 42 b of the primary pulley 42, and a V-shape formed by a fixed pulley 43 a and a movable pulley 43 b of the secondary pulley 43. It is stretched over the sheave surface.

  The final reduction mechanism 5 transmits the rotation input from the transmission output shaft 41 of the continuously variable transmission mechanism 4 to the drive wheels 6. The final reduction mechanism 5 includes a plurality of gear trains 52 and a differential gear 56. An axle 51 is connected to the differential gear 56 to rotate the drive wheel 6.

  The drive wheel 6 is provided with a brake 61. The braking force of the brake 61 is controlled by the brake actuator 62 based on a command from a brake control unit 82 described later. The brake actuator 62 controls the braking force of the brake 61 based on the detection amount of the brake sensor 64 that detects the depression force of the brake pedal 63. The brake actuator 62 may be hydraulic, and the brake sensor 64 converts the brake pressure into the brake hydraulic pressure based on the depression force of the brake pedal 63, and the brake actuator 62 controls the braking force of the brake 61 based on the brake hydraulic pressure. May be.

  The primary pulley 42 and the secondary pulley 43 of the continuously variable transmission mechanism 4 are supplied with hydraulic pressure from the transmission hydraulic pressure control unit 7.

  The transmission hydraulic pressure control unit 7 includes a regulator valve 71 for controlling the hydraulic pressure generated by the hydraulic oil (also used for lubricating oil) output from the oil pump 70 to the line pressure PL, and a line pressure solenoid 72 for operating the regulator valve 71. With. The line pressure PL is supplied to the first pressure regulating valve 74 and the second pressure regulating valve 77 through the line pressure oil passage 73. The first pressure regulating valve 74 is operated by the primary pressure solenoid 75 and supplies the primary hydraulic pressure to the primary pressure oil passage 76. The second pressure regulating valve 77 is operated by the secondary pressure solenoid 78 to supply the secondary hydraulic pressure to the secondary pressure oil passage 79. The line pressure solenoid 72, the primary pressure solenoid 75, and the secondary pressure solenoid 78 operate according to a command from the CVT control unit 81 and control each hydraulic pressure. The transmission hydraulic pressure control unit 7 supplies lubricating oil to the forward / reverse switching mechanism 3, the continuously variable transmission mechanism 4, and the like.

  The CVT control unit 81, the brake control unit 82, the motor control unit 83, and the engine control unit 84 are connected together with a hybrid control module 80 described later via a CAN communication line 90 that can communicate with each other.

  The CVT control unit 81 (transmission control device) detects a primary rotation sensor 88 that detects the rotation speed of the primary pulley 42 (transmission input rotation speed) and a secondary that detects the rotation speed of the secondary pulley 43 (transmission output rotation speed). A signal from the rotation sensor 89 or the like is input, and a command is sent to the transmission hydraulic pressure control unit 7 based on the input signal. The hydraulic pressure of the transmission hydraulic pressure control unit 7 is supplied to the continuously variable transmission mechanism 4 and the forward / reverse switching mechanism 3. That is, the CVT control unit 81 determines the primary hydraulic pressure supplied to the primary hydraulic chamber 45, the secondary hydraulic pressure supplied to the secondary hydraulic chamber 46, and the engaged state of the forward clutch 31 and the reverse brake 32 of the forward / reverse switching mechanism 3. Control.

  The hybrid control module 80 manages the energy consumption of the entire vehicle and controls the drive of the engine 1 and the motor generator 2 so as to increase the energy efficiency.

  The hybrid control module 80 receives signals from the accelerator opening sensor 85, the vehicle speed sensor 86, the inhibitor switch sensor 87, and the like and information from each control unit via the CAN communication line 90. The hybrid control module 80 calculates a target driving torque and a target braking torque from these signals and information. Subtracting the regenerative braking torque, which is the maximum regenerative torque that can be generated by the motor generator 2, from the target braking torque is the hydraulic braking torque, and the target braking torque is determined by the sum of the regenerative braking torque and the hydraulic braking torque. obtain. The hybrid control module 80 collects electric power by causing the motor generator 2 to perform regeneration during deceleration.

  The brake control unit 82 outputs a drive command to the brake actuator 62 based on the control command from the hybrid control module 80. The brake control unit 82 acquires information on the brake fluid pressure generated by the brake actuator 62 and sends it to the hybrid control module 80.

  The motor control unit 83 outputs a target powering command (positive torque command) or a target regeneration command (negative torque command) to the inverter 21 based on a control command from the hybrid control module 80. The motor control unit 83 acquires actual motor drive torque information by detecting the actual current value applied to the motor generator 2 and sends it to the hybrid control module 80.

  The engine control unit 84 outputs a drive command to the engine control actuator 10 based on the control command from the hybrid control module 80. The engine control unit 84 sends actual engine drive torque information obtained from the rotational speed of the engine 1 and the fuel injection amount to the hybrid control module 80.

  The hybrid control module 80 executes control corresponding to the following modes.

  The hybrid vehicle of the first embodiment has an electric vehicle mode (hereinafter referred to as “EV mode”) and a hybrid vehicle mode (hereinafter referred to as “HEV mode”).

  The “EV mode” is a mode in which the first clutch 12 is disengaged and the drive source is only the motor generator 2. The “EV mode” is selected, for example, when the required driving force is low and the battery SOC (State of Charge) is sufficiently secured.

  The “HEV mode” is a mode in which the first clutch 12 is engaged and the drive source is the engine 1 and the motor generator 2. The “HEV mode” is selected, for example, when the required driving force is large or when the battery SOC for driving the motor generator 2 is insufficient.

[Transmission control configuration of continuously variable transmission mechanism]
The shift control of the continuously variable transmission mechanism 4 executed by the CVT control unit 81 is performed at an operating point specified by the accelerator opening APO detected by the accelerator opening sensor 85 and the vehicle speed VSP detected by the vehicle speed sensor 86 ( VSP, APO) is determined by determining the target primary rotational speed Npri ^{* according} to the position on the shift schedule in FIG.

Here, as shown in FIG. 2, the shift schedule (shift target) depends on the lowest gear ratio and the highest gear ratio according to the driving point (VSP, APO) indicated by the vehicle speed VSP and the accelerator opening APO. The speed ratio is set to be continuously variable within the range of the speed ratio width. For example, when the vehicle speed VSP is constant, if the accelerator depression operation is performed, the target primary rotation speed Npri ^* increases and the driving point (VSP, APO) moves toward the lowest gear ratio, so a downshift occurs. On the other hand, when the accelerator returning operation is performed, the target primary rotational speed Npri ^* decreases, and the operating point (VSP, APO) moves toward the highest gear ratio and is upshifted. Further, when the accelerator opening APO is constant, an upshift occurs when the vehicle speed VSP increases, and a downshift occurs when the vehicle speed VSP decreases.

  Note that the thick line characteristic in FIG. 2 is a coast shift line indicating the target speed ratio when the vehicle is coasting with the accelerator released (APO = 0). In other words, when the vehicle decelerates, as shown by the arrow A in FIG. 2, as the vehicle speed VSP decreases, a downshift occurs in which the gear ratio changes toward the lowest gear ratio, and when the vehicle speed VSP = 0 (stopped state). Returned to the lowest gear ratio.

In the transmission hydraulic pressure control of the continuously variable transmission mechanism 4, when the target primary rotational speed Npri ^* is determined, the differential pressure between the primary hydraulic pressure Ppri and the secondary hydraulic pressure Psec is fed back so as to eliminate the deviation from the actual primary rotational speed Npri. It is done by controlling. The actual primary rotation speed Npri is acquired from the primary rotation sensor 88.

[Shift speed control processing configuration]
FIG. 3 is a flowchart illustrating the flow of a shift speed control process executed by the CVT control unit according to the first embodiment. Hereinafter, each step of the shift speed control process of the first embodiment will be described based on the flowchart shown in FIG.

In step S1, a target value (target primary stroke position) of the stroke position of the primary pulley 42 is calculated based on the current target gear ratio, and a target value (target primary stroke speed) of the primary pulley 42 is calculated. Then, the process proceeds to step S2.
Here, in order to calculate the “target primary stroke position”, first, the current winding radius of the belt 44 in the primary pulley 42 is calculated from the target gear ratio. Then, the target primary stroke position is calculated from the calculated current winding radius, the winding radius of the belt 44 in the primary pulley 42 at the lowest gear ratio, and the sheave surface inclination angle of the primary pulley 42.
Further, in order to calculate the “target primary stroke speed”, it is calculated by a difference equation per sampling time of the target primary stroke. It should be noted that, based on the vehicle speed and the accelerator opening, for example, referring to a shift schedule as shown in FIG. 2, the ultimate transmission ratio that is the final target transmission ratio is calculated and the target transmission ratio is subtracted from the ultimate transmission ratio Then, a value obtained by dividing by the target time constant (standard time constant preset for each shift type) is determined as the target shift speed. Then, the target primary stroke speed may be calculated by multiplying the target shift speed by a pulley stroke speed magnification (ratio between the pulley stroke speed and the shift speed).

In step S2, following the calculation of the target primary stroke position and the target primary stroke speed in step S1, it is determined whether the speed (vehicle speed) of the hybrid vehicle is equal to or higher than a preset control start permission vehicle speed. If YSE (vehicle speed ≧ control start permission vehicle speed), the process proceeds to step S3. If NO (vehicle speed <control start permission vehicle speed), the process proceeds to step S13.
Here, the “control start permission vehicle speed” is a vehicle speed that is assumed to be zero before the speed ratio reaches the lowest speed ratio when downshifting at the speed set at the “limit speed”. That is, in a state where the vehicle speed is equal to or lower than the “control start permission vehicle speed”, if the downshift speed (down speed) is set to “limit speed”, the vehicle stops before the target speed ratio reaches the lowest speed ratio. There is a risk that the risk of starting at a higher gear ratio than the lowest gear ratio increases. Therefore, the shift speed control process of the first embodiment is performed only when the vehicle speed ≧ the control start permission vehicle speed.
The vehicle speed is detected by a vehicle speed sensor 86. The “control start permission speed” is set in advance based on experiments or the like.

In step S3, following the determination that vehicle speed ≧ control start permission vehicle speed in step S2, it is determined whether or not the accelerator pedal is released, that is, whether or not the accelerator is released. If YES (accelerator OFF), the process proceeds to step S4. If NO (accelerator ON), the process proceeds to step S13.
The accelerator pedal ON / OFF state is detected by an accelerator opening sensor 85.

In step S4, following the determination that the accelerator is OFF in step S3, it is determined whether or not the vehicle is in a deceleration state in which the brake pedal is depressed. If YES (brake ON), the process proceeds to step S5. If NO (brake OFF), the process proceeds to step S13.
The brake sensor 64 detects the ON / OFF state of the brake pedal.

In step S5, following the determination that the brake is ON in step S4, it is determined whether or not the deceleration request generated by the depression of the brake pedal is a slow deceleration. In the case of YSE (slow deceleration request), the process proceeds to step S6. If NO (request for rapid deceleration), the process proceeds to step S13.
Here, whether or not the deceleration request is a slow deceleration is determined by filtering the actual rotational speed difference (detected by the secondary rotation sensor 89) of the secondary pulley 43 per predetermined time using a predetermined dedicated cut-off low-pass filter. Determination is made based on the deceleration (deceleration G) calculated by processing. If the calculated deceleration continues below the preset “control permission deceleration G” for a predetermined time, it is determined that the deceleration is a slow deceleration request. If the deceleration exceeds “control permission deceleration G”, the deceleration is abrupt. Judge as a request.
The “control permission deceleration G” allows a deceleration G in which the start acceleration does not become uncomfortable when the vehicle stops without using the lowest gear ratio with the speed of the downshift as the limiting speed, and an inertia shock on the deceleration side is allowed. Decide on balance with deceleration G.

In step S6, following the determination of the slow deceleration request in step S5, whether or not the direction of the target transmission line is the downshift direction, that is, whether or not the target transmission ratio has changed to the low-side transmission ratio. Determine whether. If YES (shift line direction = downshift), the process proceeds to step S7. If NO (shift line direction ≠ downshift), the process proceeds to step S13.
Here, the target shift line is determined based on the shift schedule shown in FIG. 2 and the operating point (VSP, APO) of the hybrid vehicle.

In step S7, following the determination that the direction of the transmission line in step S6 is downshift, whether or not the actual gear ratio has changed to the downshift side, that is, the actual gear ratio has changed to the low side gear ratio. Judge whether or not. If YES (actual gear ratio = downshift), the process proceeds to step S8. If NO (actual gear ratio ≠ downshift), the process proceeds to step S13.
Here, the actual gear ratio is calculated by dividing the rotation speed of the primary pulley 42 detected by the primary rotation sensor 88 by the rotation speed of the secondary pulley 43 detected by the secondary rotation sensor 89.

In step S8, following the determination that the actual transmission ratio = downshift in step S7, it is determined whether or not the shift speed can be limited. If YES (shift speed can be limited), the process proceeds to step S9. If NO (shift speed cannot be limited), the process returns to step S3.
Here, whether or not the shift speed can be limited depends on whether or not the hybrid vehicle has the target primary stroke speed (calculated in step S1) when the target primary stroke speed is decelerated at a predetermined deceleration. Judgment is made based on whether or not the target primary stroke position is a lower position on the calculation than the position having the lowest gear ratio at the timing when the vehicle speed reaches a predetermined minimum vehicle speed.
The “predetermined deceleration” is a deceleration at which the change in the actual speed ratio can follow the change in the target speed ratio, and the actual speed ratio during the downshift is the target speed ratio reached during coasting. Is set to the maximum value of deceleration (obtained in advance based on experiments, etc.) that does not result in a lower gear ratio. The shift speed when the downshift speed is decelerated at the “predetermined deceleration” is a “limit speed” that is slower than the “standard speed”. That is, the “restricted speed” is the maximum value of the downshift speed at which the actual speed ratio during the downshift of the continuously variable transmission mechanism 4 does not become the lower speed ratio than the ultimate target speed ratio during coasting.
The “predetermined minimum vehicle speed” is the minimum value of the rotational speed that can be detected by the secondary rotational sensor 89 (the rotational speed sensor that detects the rotational speed of the transmission output shaft 41 of the continuously variable transmission mechanism 4). It is about 4-5km / h. The “timing at which the vehicle speed reaches a predetermined minimum vehicle speed” is calculated based on the vehicle speed at the time of calculation (detected by the vehicle speed sensor 86) and the deceleration G at the time of calculation.
Further, when the actual gear ratio reaches the lowest gear ratio, a minute value remains as the target primary stroke speed. This “minor value” is the speed necessary to prevent the gear ratio Low return failure (the gear shift stops before the target gear ratio reaches the lowest gear ratio) due to a computation error. However, the downshift is continued until the actual gear ratio surely reaches the lowest gear ratio.

  When the target primary stroke speed is decelerated at a predetermined deceleration, the target primary stroke position is determined to be lower than the position where the lowest gear ratio is reached when the vehicle speed reaches the predetermined minimum vehicle speed. Then, it is determined that the speed change speed can be limited. As a result, when the shift speed changeover timing from “standard speed” to “restricted speed” is “restricted speed” and the downshift of the continuously variable transmission mechanism 4 is performed, the vehicle speed reaches the predetermined minimum vehicle speed. The actual gear ratio is set to reach the lowest gear ratio.

Specifically, it is determined that the shift speed can be limited when the following formulas (1) to (3) are established.
0 = V ₀ + a * t (1)
_{x = x 0 + 1/2} * a * t 2 ... (2)
x ≦ x_L ₀ (3)
Where V ₀ = target primary stroke speed at the current time [mm / s]
a = predetermined deceleration [mm / s ₂ ]
x ₀ = Current target primary stroke position [mm]
L ₀ = target primary stroke position at the lowest gear ratio [mm]
t = time until the vehicle speed reaches the minimum speed [s]
It is.

In step S9, following the determination that the shift speed can be limited in step S8, the shift speed when downshifting while limiting the target primary stroke speed with the “predetermined deceleration” set in step S8, that is, The “limit speed” is calculated, and the process proceeds to step S10.
Here, the target primary stroke speed (limit speed) at the time of limiting the shift speed is obtained from the “predetermined deceleration” and the current target primary stroke speed (calculated in step S1).

In step S10, following the calculation of the target primary stroke speed (restricted speed) at the time of limiting the shift speed in step S9, from the target primary stroke speed (restricted speed) calculated in this step S9, Set a constant (constant shifting time constant). Then, using this limited speed change time constant, the target speed ratio, which is a transient target value when changing the speed ratio to the lowest speed speed ratio, which is the target value that should finally be reached while limiting the speed, is set. Calculate and go to step S11.
Here, the speed ratio change is obtained by multiplying the speed ratio change amount per unit primary stroke determined from the geometry of the belt 44 of the continuously variable transmission mechanism 4 and the target primary stroke speed restriction value calculated in step S9. A new target gear ratio can be calculated by obtaining the ratio and integrating the speed ratio change rate. However, in this case, there is a possibility that a step (step-like change) may occur in the target gear ratio upon returning from the upshift such as when the accelerator pedal is depressed during the downshift. Therefore, the target gear ratio is calculated after converting to a time constant.

In step S11, following the calculation of the target speed ratio in step S10, it is determined whether or not the actual speed ratio in the continuously variable transmission mechanism 4 has changed. If YES (change in gear ratio), the process proceeds to step S12. If NO (speed ratio fixed), the process proceeds to step S13.
Here, the actual gear ratio is calculated from the number of rotations of the primary pulley 42 / the number of rotations of the secondary pulley 43, as calculated in step S7. However, the detection accuracy of the primary rotation sensor 88 and the secondary rotation sensor 89 deteriorates in the low rotation speed region. Therefore, the restriction on the speed change is canceled in the low rotation speed region.

In step S12, following the determination that there is a change in the gear ratio in step S11, a downshift is performed with the speed change speed set to “limit speed”, and the process returns to step S3.
That is, the target primary rotational speed Npri ^* is determined so that the actual gear ratio follows the target gear ratio set in step S10. Then, feedback control is performed on the differential pressure between the primary hydraulic pressure Ppri and the secondary hydraulic pressure Psec so as to eliminate the deviation between the target primary rotational speed Npri ^* and the actual primary rotational speed Npri.

In step S13, a normal shift time constant is set such that the shift speed becomes a preset “standard speed”. Then, using this normal speed change time constant, a target speed ratio that is a transient target value when changing the speed ratio to the lowest speed speed ratio that is the target value that should finally be reached is calculated, and the process proceeds to step S14. move on.
The “normal shift time constant” is set in advance based on the response of the hydraulic pressure supplied to the continuously variable transmission mechanism 4, the magnitude of the shift request, and the like.

In step S14, following the calculation of the target gear ratio in step S13, a shift with the shift speed set to "standard speed" is executed, and the process proceeds to the end.
That is, the target primary rotational speed Npri ^* is determined so that the actual gear ratio follows the target gear ratio set in step S13. Then, feedback control is performed on the differential pressure between the primary hydraulic pressure Ppri and the secondary hydraulic pressure Psec so as to eliminate the deviation between the target primary rotational speed Npri ^* and the actual primary rotational speed Npri.

Next, the operation will be described.
The operation of the control device for the continuously variable transmission according to the first embodiment will be described separately for “shift speed control operation” and “other characteristic operations”.

[Shift speed control function]
FIG. 4 shows an absolute value of an accelerator flag, a brake flag, a target transmission line, a target transmission ratio, an actual transmission ratio, and a target primary stroke speed when the transmission speed control is performed in the continuously variable transmission control apparatus according to the first embodiment. -It is a time chart which shows each characteristic of a target primary stroke position, vehicle speed, and the vehicle G. Hereinafter, based on FIG.3 and FIG.4, the speed-change control effect | action of Example 1 is demonstrated.

In the hybrid vehicle of Embodiment 1, when the accelerator pedal is released at the time t ₁₁ shown in FIG. 4, the accelerator flag is changed to OFF from ON. Thereby, on the shift schedule (see FIG. 2), the target shift line where the operating point (VSP, APO) is located becomes the highest shift line indicating the highest shift ratio, and the target shift ratio also follows the change of the shift line. To change. This target gear ratio is obtained by low-pass filter processing of the target shift line.

Then, the target speed ratio reaches the highest High speed ratio, at time t ₁₂ time, starts changing the target shift line to the Low side speed ratio side. Thereby, the direction of the target shift line becomes the downshift direction. At this time, the target gear ratio also starts to change toward the low side gear ratio almost simultaneously.
Further, when the brake pedal at time t ₁₃ when it is depressed, the brake flag is switched to ON from OFF, the vehicle speed deceleration G is increased begins to decrease.

Then, at time t ₁₄ when the actual gear ratio starts to change to the Low side speed ratio from the outermost High speed ratio, the actual gear ratio starts to change to the downshift side. Further, at time t ₁₄ the time, the vehicle speed is above the "control start permission speed". On the other hand, the deceleration G remains below the “control permission deceleration G”.
Thus, in the flowchart shown in FIG. 3, the process proceeds from step S1, step S2, step S3, step S4, step S5, step S6, step S7, and step S8, and it is determined whether or not the shift speed can be limited. Is done.

However, the time t ₁₄ time, minimum from target primary stroke speed of the time t ₁₄ time (x in FIG. 4) be decelerated the target primary stroke speed at a predetermined deceleration, the vehicle speed of the hybrid vehicle is in a predetermined at a timing reaching vehicle speed (time t ₁₆ time), the target primary stroke position, not to the Low side position on the operation from the position is the uppermost Low speed ratio. Therefore, it is determined that the speed limit cannot be limited, and the process proceeds from step S13 to step S14, where the speed change is set to “standard speed” and the speed change (downshift) is performed.
Note that the speed change speed at this time is set to gradually increase simultaneously with the start of the downshift, and the speed change speed gradually increases.

Then, at time t ₁₅ the time, there is the vehicle speed is "control start permission speed" or more, the above equation (1) to (3) is satisfied, the target primary stroke speed of the time t ₁₅ time (y 4) from slowing the target primary stroke speed at a predetermined deceleration, at the timing when the vehicle speed of the hybrid vehicle reaches a predetermined minimum vehicle speed (time t ₁₆ time), the target primary stroke position is the position where the outermost Low speed ratio Is also determined to be the low position in the calculation. Accordingly, assuming that the downshift speed can be limited, the process proceeds from step S8 to step S9 to step S10.

As a result, a preset “predetermined deceleration (the maximum value of deceleration at which the actual gear ratio during downshift does not become the lower gear ratio than the target gear ratio during coasting)” and time t ₁₅ Based on the target primary stroke speed at the time (y in FIG. 4), the target primary stroke speed (limit speed) at the time of limiting the shift speed is calculated. Then, a shift time constant (limit shift time constant) when the shift speed is limited is set from the limit speed, and the target gear ratio is calculated using the limit shift time constant.

Then, at the time this time t _15, the gear ratio because of the change, the process proceeds to step S11 → step S12, executes the downshift in terms of setting the shift speed in the "speed limit". That is, the primary stroke speed is set to “limit speed” and the primary stroke speed is reduced.
As a result, during the period during which the transmission speed is decelerating, the speed change of the target speed ratio becomes more gradual than when the speed change speed is set to the “standard speed”, and the actual speed ratio is more reasonable than the target speed ratio changes. Can follow. When the vehicle speed at a time t ₁₆ when the target speed ratio at the timing when reaching the "minimum speed" reaches the top Low speed ratio can reach almost simultaneously actual speed ratio is also highest Low speed ratio.

As described above, in the first embodiment, when the speed change speed is set to the “limit speed” that is slower than the “standard speed”, when the continuously variable transmission mechanism 4 is downshifted, the brake pedal is depressed to decelerate, In addition, it is performed in at least a part of the period after the condition that the actual speed ratio of the continuously variable transmission mechanism 4 changes to the downshift side is satisfied.
In other words, based on the fact that the shift to the target gear ratio is a downshift and the brake pedal is depressed, the actual gear ratio (actual gear ratio) has changed to the downshift side. The shift speed (down speed) is set to a relatively slow “limit speed”.

Therefore, when the accelerator pedal is released, the brake pedal is depressed while the target gear ratio is upshifted to the highest gear ratio or the target gear ratio (coast gear line) during coasting. However, the shift speed does not slow during the upshift, and after that, if the actual gear ratio starts a downshift along the coast shift line, the shift speed can be slowed.
As a result, the actual gear ratio during deceleration does not become the highest gear ratio or the gear ratio lower than the coast gear line, and it is possible to prevent unnecessary engine brakes from acting during upshifting, and The unpleasant feeling given can be reduced.

In addition, in the first embodiment, the downshift speed is accelerated in the initial shift period from the start of the downshift of the continuously variable transmission mechanism 4 to a predetermined timing, and thereafter in the late shift period from the predetermined timing to the completion of the shift. The actual speed ratio is made to reach the target speed ratio by decelerating the downshift speed, but is set to the “limit speed” in the period during which the downshift speed is decelerated (the latter period of the shift).
Thus, the shift speed is not limited in the shift initial period in which the shift speed is accelerated from the start of the downshift. Therefore, the difference between the actual transmission ratio and the final target transmission ratio (lowest transmission ratio) is large, and even if the transmission speed is accelerated, the transmission overshoot hardly occurs and the possibility of occurrence of a deceleration shock is low. In the initial shift period, the downshift can be promptly advanced. Then, in the latter half of the shift period in which the shift speed is reduced, the shift speed is slowed down so that the actual shift ratio can reach the lowest shift ratio at an appropriate timing and the shift can be completed. Can be suppressed.

[Other characteristic effects]
In the control device of the first embodiment, as described above, at the time of a downshift that occurs when the brake pedal 63 is depressed to decelerate, the speed change speed (down speed change speed) at this time is set to a relatively slow “limit speed”.
As a result, it is possible to prevent the primary pulley 42 from stopping after the intended timing due to the influence of hydraulic response, pulley inertia force, or the like.

  That is, generally, when the downshift speed is relatively fast, the primary stroke speed associated with the deceleration is also increased. When the gear ratio is downshifted to the lowest gear ratio, the downshift is completed when the lowest gear ratio is reached. Therefore, as shown by the thin broken line (comparative example) in FIG. At the timing when reaches the lowest gear ratio, the target primary stroke position reaches the lowest position and stops, and the target primary stroke speed becomes zero. At this time, the target primary stroke speed is set to “standard speed” and increases (accelerates) simultaneously with the start of the downshift. When the target gear ratio is close to the lowest gear ratio, the target primary stroke speed rapidly decreases (decelerates). Zero.

However, in actuality, the primary pulley 42 stops after the intended timing due to the hydraulic response and the pulley inertia force. As a result, as indicated by a broken line in FIG. 5, the actual transmission ratio of the continuously variable transmission mechanism 4 becomes a lower side transmission ratio than the ultimate target transmission ratio (coast transmission line) during coasting, and is mechanically the highest. The low gear ratio is reached. In other words, a shift overshoot occurs, and the primary pulley rotation speed suddenly changes (stops) along the lowest shift line, and the operating point (VSP, APO) indicated by the vehicle speed VSP and the accelerator opening APO is 2 is a downshift that is further away from the target primary rotation speed Npri ^* indicated by the coast shift line that is the target transmission gear ratio during coasting on the shift schedule shown in FIG. Therefore, a difference is generated between the input rotation speed and the output rotation speed of the continuously variable transmission mechanism 4, and a deceleration shock (a push-up shock for releasing the inertia) is generated, which makes the driver feel uncomfortable.

  On the other hand, as in the control device of the first embodiment, the primary pulley having a high primary stroke speed is set by setting the shift speed (down shift speed) at the time of downshift to a “limit speed” that is slower than the “standard speed”. Even when downshifting to the lowest gear ratio for suddenly stopping 42, the primary pulley 42 can be prevented from stopping after the intended timing. That is, as indicated by a solid line in FIG. 5, the shift overshoot can be avoided and the rotation speed of the primary pulley can be reduced smoothly. Thereby, deceleration shock (push-up shock for releasing inertia) can be reduced, and the occurrence of uncomfortable feeling can be suppressed.

In particular, in the first embodiment, when calculating the speed limit, the deceleration when the transmission speed is decelerated is set so that the actual transmission ratio during the downshift of the continuously variable transmission mechanism 4 is greater than the target transmission speed ratio during coasting. Is also set to the maximum value of deceleration that does not become the Low side gear ratio. Therefore, the speed change speed is set to the maximum speed change speed at which the actual speed change ratio during the downshift does not become the lower speed change ratio than the target speed change ratio during coasting.
As a result, when downshifting along the target transmission ratio during coasting, the actual transmission ratio does not become lower than the target transmission ratio during coasting, and shift overshoot is prevented. Thus, the actual gear ratio can be smoothly reached to the lowest gear ratio. As a result, the deceleration shock and the driver's uncomfortable feeling can be effectively reduced.

  In the control device according to the first embodiment, the speed change speed when switching the speed change from the “standard speed” to the “limit speed” is set to the “limit speed”, and the continuously variable transmission mechanism. When the downshift of No. 4 is performed, the actual gear ratio is set to reach the lowest gear ratio (final target gear ratio) at the timing when the vehicle speed reaches a predetermined minimum vehicle speed.

This allows the hybrid vehicle to stop even if it takes more time to complete the downshift by setting the shift speed to “Limited Speed” than when the shift speed is set to “Standard Speed”. Prior to the timing when (vehicle speed = zero), the actual gear ratio can be set to the lowest gear ratio that is the final target gear ratio. That is, when the vehicle is stopped, the gear ratio of the continuously variable transmission mechanism 4 can be reliably set to the lowest gear ratio.
As a result, it is possible to prevent the gear ratio of the continuously variable transmission mechanism 4 from being the higher gear ratio than the lowest gear ratio when starting.

In the first embodiment, the “minimum vehicle speed” at this time is set to the minimum value of the rotation speed that can be detected by the secondary rotation sensor 89 that detects the rotation speed of the transmission output shaft 41 of the continuously variable transmission mechanism 4. ing.
Here, a sensor that detects the rotation speed such as the secondary rotation sensor 89 cannot accurately detect the rotation speed in the low rotation area immediately before the vehicle stops. Therefore, by setting the “minimum vehicle speed” to the minimum value of the rotation speed that can be detected by the secondary rotation sensor 89, the output rotation speed of the continuously variable transmission mechanism 4 can be the minimum rotation speed that can be detected by the secondary rotation sensor 89. The actual gear ratio reaches the lowest gear ratio before reaching the value, so that the actual gear ratio can be reliably shifted to the lowest gear ratio before the vehicle stops.
In addition, since the “minimum vehicle speed” is set to the minimum value of the rotational speed that can be detected by the secondary rotation sensor 89, the “minimum vehicle speed” can be set to a minimum value, and the shift speed switching timing can be set. Can be as late as possible. As a result, it is possible to ensure as long as possible the time for downshifting with the “standard speed”, and it is possible to promote shifting to the lowest gear ratio (downshifting).

Furthermore, in Example 1, as a "speed limit" at which actual gear ratio of the continuously variable transmission mechanism 4 reaches the uppermost Low speed ratio (time t ₁₆ time) is set to a predetermined minute value.
Therefore, it is possible to prevent the downshift from stopping due to the target primary stroke speed becoming zero before the target gear ratio reaches the lowest gear ratio due to a calculation error. That is, even if the timing at which the target gear ratio reaches the lowest gear ratio and the timing at which the target primary stroke speed becomes zero, the actual gear ratio of the continuously variable transmission mechanism 4 can be returned to the lowest gear ratio. It is possible to prevent the gear ratio Low returning failure (the gear shift is stopped before the target gear ratio reaches the lowest gear ratio).

Further, in the first embodiment, when the downshift is performed at the speed set to the “limit speed”, the “control start permission speed”, which is a speed at which the vehicle speed is assumed to be zero before the speed ratio reaches the lowest speed ratio. When the vehicle speed of the hybrid vehicle is less than the “control start permission speed”, the shift speed is not limited, and the downshift is executed while maintaining the “standard speed”.
In other words, if the gear ratio is set to “Limited speed” and the gear ratio cannot reach the lowest gear ratio before stopping, the gear speed during downshift should be set to “Limited speed”. Is prohibited.

  Therefore, by setting the speed change speed to the “limit speed”, it is possible to avoid that the speed ratio cannot reach the lowest speed ratio before the vehicle stops. Thereby, in the continuously variable transmission mechanism 4, it is possible to prevent the vehicle from stopping before the transmission gear ratio reaches the lowest transmission gear ratio and starting at the high transmission gear ratio, resulting in insufficient driving force at the time of starting. .

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

(1) a continuously variable transmission mechanism 4 disposed between a driving source for driving (motor generator 2) and driving wheels 6;
Shift control means (CVT control unit 81) for shifting the gear ratio of the continuously variable transmission mechanism 4 at a standard speed set in advance toward the target gear ratio;
The shift control means (CVT control unit 81) is a condition that the brake pedal 63 is depressed when the continuously variable transmission mechanism 4 is downshifted, and the actual transmission ratio of the continuously variable transmission mechanism 4 changes to the downshift side. The down-shift speed in at least a part of the period after the above is established is set to a speed limit slower than the standard speed.
As a result, it is possible to prevent unnecessary engine braking from acting during upshifting, and to reduce the uncomfortable feeling given to the driver.

(2) The shift control means (CVT control unit 81) accelerates the downshift speed from the start of the downshift of the continuously variable transmission mechanism 4, and then decelerates the downshift speed to obtain the actual gear ratio. When the target speed ratio is reached, the down transmission mechanism is set to the speed limit during a period during which the down transmission speed is decelerated.
As a result, in addition to the effect of (1), it is possible to make the actual gear ratio reach the lowest gear ratio at an appropriate timing while promptly proceeding with the downshift, and to appropriately suppress the occurrence of shock.

(3) The speed change control means (CVT control unit 81) is configured to reduce the speed limit so that the actual speed change ratio during the downshift of the continuously variable transmission mechanism 4 is lower than the target speed change ratio during coasting. The maximum shift speed is set to a value that does not occur.
As a result, in addition to the effect of (1) or (2), the actual gear ratio during deceleration does not become the lower gear ratio than the ultimate target gear ratio during coasting, and the primary pulley 42 has intended timing. It is possible to prevent the vehicle from stopping later.

(4) The shift control means (CVT control unit 81) has performed the downshift of the continuously variable transmission mechanism 4 at the limit speed at the timing of switching the down shift speed from the standard speed to the limit speed. In some cases, the actual transmission ratio of the continuously variable transmission mechanism 4 is set so as to reach the lowest transmission ratio at the timing when a predetermined vehicle speed (minimum vehicle speed) is reached.
As a result, in addition to any of the effects (1) to (3), the actual transmission ratio of the continuously variable transmission mechanism 4 can reach the lowest transmission ratio before the vehicle speed becomes zero and the vehicle stops. The starting risk can be reduced at a gear ratio higher than the lowest gear ratio.

(5) The shift control means (CVT control unit 81) determines the minimum value of the rotation speed that can be detected by a rotation speed sensor (secondary rotation sensor 89) that detects the output shaft rotation speed of the continuously variable transmission mechanism 4. It was set as the structure set to predetermined vehicle speed (minimum vehicle speed).
Thereby, in addition to the effect of (4), a predetermined vehicle speed (minimum vehicle speed) can be appropriately detected, and the actual gear ratio can be reliably shifted to the lowest gear ratio before the vehicle stops. Further, it is possible to promote the downshift by delaying the shift speed switching timing as much as possible and extending the downshift time by the “standard speed”.

(6) The speed change control means (CVT control unit 81) is configured to set a predetermined minute value as the speed limit when the actual speed ratio of the continuously variable transmission mechanism 4 reaches the lowest speed ratio.
Thereby, in addition to the effect of any one of (1) to (5), it is possible to prevent the occurrence of the lowest gear ratio return failure due to a calculation error.

(7) The shift control means (CVT control unit 81), when the downshift speed is set to the limit speed, when the speed change ratio cannot reach the lowest speed ratio before stopping, The downshift speed is prohibited from being set to the speed limit.
As a result, in addition to any of the effects (1) to (6), the continuously variable transmission mechanism 4 prevents the vehicle from stopping before the gear ratio reaches the lowest gear ratio, and the high gear ratio. It is possible to prevent starting at.

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

In the first embodiment, the present invention is applied to a hybrid vehicle including the engine 1 and the motor generator 2 as a driving source for travel. However, the present invention is not limited to this. Since the present invention can be applied to any vehicle provided with a continuously variable transmission mechanism, it may be an engine vehicle equipped with only an engine as a driving source for driving or an electric vehicle equipped with only a motor generator.
In the first embodiment, the continuously variable transmission mechanism 4 is an example of a belt type continuously variable transmission having a primary pulley 42, a secondary pulley 43, and a belt 44. And a toroidal continuously variable transmission having a plurality of power rollers, or a chain continuously variable transmission that transmits power between a pair of pulleys by the tension of the chain.

In Example 1, the brake pedal 63 is depressed, and, among the period after the conditions in which the actual speed ratio of the continuously variable transmission mechanism 4 is changed to the downshift side is satisfied (time t ₁₂ after 4) In the above example, the down speed change mechanism is set to the “limit speed” during the period in which the down speed is reduced. However, the present invention is not limited to this. For example, the downshift speed is set to the “limit speed” during the entire period from when the brake pedal 63 is depressed and the actual gear ratio changes to the downshift side until the downshift is completed. It may be set, or the downshift speed may be set to the “limit speed” during the period in which the downshift speed is accelerated. Further, the downshift speed in an arbitrary period may be set to the “limit speed” regardless of the acceleration / deceleration of the downshift speed.

The control device according to the first embodiment reduces the down speed when the accelerator pedal is released and when a predetermined condition such as the actual gear ratio changing to the downshift side is satisfied when the brake pedal is depressed and decelerated. Set the shift speed during shifting to "Limited speed".
Therefore, the shift speed is delayed at the time of downshift caused by the deceleration intended to stop the vehicle. For example, at the time of the downshift caused by the deceleration caused by the lever operation intended for the engine brake, the shift speed is reduced. The shift speed control according to the present invention for delaying the speed may not be performed.

  Further, in an operating state where the oil amount balance from the oil pump 70 is not sufficient, such as at low temperatures when the viscosity of the hydraulic oil becomes high, the speed change speed becomes slower than expected, and the continuously variable transmission mechanism 4 is not realized until the vehicle stops. The gear ratio may not reach the lowest gear ratio. Therefore, in order to avoid this, when the oil amount balance is not sufficient, the shift speed control of the present invention for delaying the shift speed need not be performed.

  Further, when the “sport mode” is set as the driving mode, which increases the response of the drive source rotation to the vehicle acceleration request than usual, it is desirable to strengthen the engine brake that acts during deceleration than in the normal mode. Also, a greater driving force is required at the time of restart. Therefore, when the “sport mode” is set, the shift speed control according to the present invention, which prioritizes that the gear ratio of the continuously variable transmission mechanism 4 returns to the lowest gear ratio when the vehicle is stopped, and delays the shift speed, It is not necessary to carry out.

  The shift speed control of the present invention for delaying the shift speed at the time of downshift is based on the starting clutch (or lock-up clutch: the forward clutch 31 of the forward / reverse switching mechanism 3 serving as the second clutch in the first embodiment). When applied to a continuously variable transmission mechanism in which the release vehicle speed of one of the reverse brake 32 and the reverse brake 32 is set to a relatively low vehicle speed side, a higher effect can be obtained.

In other words, in an electric vehicle equipped with a power train that has a regeneration function that regenerates energy from the drive wheels, such as a hybrid vehicle or an electric vehicle, the traveling area that is regenerated during deceleration traveling should be as long as possible. Is desired. Therefore, at the time of deceleration, the clutch release vehicle speed at the time of releasing the starting clutch is set in the low vehicle speed range in order to regenerate the power from the drive wheels until reaching the low vehicle speed. The “low vehicle speed range” is, for example, about 10 km / h.
In such an electric vehicle, the vehicle speed reaching the lowest speed ratio of the continuously variable transmission mechanism in the deceleration state (coast running state) is higher than the clutch release vehicle speed.

  Therefore, at the time of downshift accompanying deceleration, the start clutch is engaged when the primary pulley stops after the intended timing, and the actual gear ratio is lower than the gear ratio on the coast shift line. This change in the gear ratio is easily transmitted as a shock to the driver.

On the other hand, a continuously variable transmission mechanism in which the clutch disengagement vehicle speed when releasing the starting clutch is set to a relatively high vehicle speed range (for example, a continuously variable vehicle mounted on a vehicle equipped with a powertrain that does not have a regeneration function). (Transmission mechanism), the vehicle speed at which the continuously variable transmission mechanism reaches the lowest speed ratio in the deceleration state (coast running state) is lower than the clutch release vehicle speed. Therefore, at the time of downshift accompanying deceleration, even if the primary pulley stops after the intended timing, the starting clutch is already released.
Therefore, even if a change occurs in which the actual gear ratio becomes a lower gear ratio than the gear ratio on the coast gear line, the change in the gear ratio is not easily transmitted as a shock to the driver.

  In this way, particularly in the case of an electric vehicle equipped with a power train having a regenerative function, the starting clutch is often engaged at the timing when the actual transmission ratio of the continuously variable transmission mechanism reaches the lowest transmission ratio. Occurrence becomes remarkable. Therefore, this shock can be reduced by the control of the present invention, and the effect becomes relatively large.

1 Engine 2 Motor generator (driving drive source)
3 Forward / reverse switching mechanism 31 Forward clutch 32 Reverse brake 4 Continuously variable transmission mechanism 41 Transmission output shaft 42 Primary pulley 43 Secondary pulley 44 Belt 6 Drive wheel 80 Hybrid control module 81 CVT control unit (transmission control means)

Claims (7)

A continuously variable transmission mechanism disposed between the driving source for driving and the driving wheel;
Shift control means for shifting the gear ratio of the continuously variable transmission mechanism at a standard speed set in advance toward the target gear ratio;
In the period after the condition that the brake pedal is depressed and the actual speed ratio of the continuously variable transmission mechanism changes to the downshift side is established during the downshift of the continuously variable transmission mechanism. A control device for a continuously variable transmission, wherein the downshift speed in at least a part of the period is set to a speed limit slower than the standard speed. In the control device for continuously variable transmission according to claim 1,
The shift control means accelerates the down shift speed from the start of the downshift of the continuously variable transmission mechanism, and then decelerates the down shift speed to reach the actual speed ratio to the target speed ratio. A control device for a continuously variable transmission, wherein the down transmission mechanism is set to the speed limit during a period during which the down transmission speed is decelerated. In the control device for a continuously variable transmission according to claim 1 or 2,
The shift control means sets the speed limit to the maximum value of the shift speed at which the actual speed ratio during the downshift of the continuously variable transmission mechanism does not become the lower speed ratio than the target speed ratio during coasting. A transmission control apparatus for a continuously variable transmission. In the control device for a continuously variable transmission according to any one of claims 1 to 3,
The shift control means is configured to switch the downshift speed from the standard speed to the limit speed when reaching a predetermined vehicle speed when the continuously variable transmission mechanism is downshifted at the limit speed. A control device for a continuously variable transmission, wherein an actual transmission ratio of the continuously variable transmission mechanism is set so as to reach a lowest transmission ratio. In the control device for continuously variable transmission according to claim 4,
In the continuously variable transmission, the shift control means sets a minimum value of a rotation speed detectable by a rotation speed sensor that detects an output shaft rotation speed of the continuously variable transmission mechanism to the predetermined vehicle speed. Control device. In the control device for a continuously variable transmission according to any one of claims 1 to 5,
The control device for a continuously variable transmission, wherein the shift control means sets a predetermined minute value as a speed limit when the actual gear ratio of the continuously variable transmission mechanism reaches the lowest gear ratio. The control device for a continuously variable transmission according to any one of claims 1 to 6,
The speed change control means sets the down speed change speed to the speed limit when the down speed change speed is set to the speed limit, and when the speed change ratio cannot reach the lowest speed ratio before stopping. A control device for a continuously variable transmission, characterized in that setting is prohibited.