JP2010025247A - Control device for continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a driver from being imparted with uncomfortable feeling during constat speed travel control by extending a vehicle speed hunting cycle during the constant travel control, in a control device for a continuously variable transmission. <P>SOLUTION: During the constant speed travel control, when it is not determined that the throttle opening of a throttle valve reaches an idle determination opening (when an idle determination flag is off), a lower limit of target primary pulley rotational speed is set to a higher first value A, and when it is determined that the throttle opening of the throttle valve reaches the idle determination opening (when the idle determination flag is on), the lower limit of the target primary pulley rotational speed is set to a lower second value B. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a continuously variable transmission control device applied to a vehicle having a constant speed traveling control function.

  As a continuously variable transmission used for a vehicle such as an automobile, there are a belt type and a toroidal type.

  A belt type continuously variable transmission is generally called CVT (Continuously Variable Transmission), and is wound around an input side primary pulley provided on an input shaft, an output side secondary pulley provided on an output shaft, and these pulleys. By changing the groove width of each pulley and changing the winding diameter of the transmission belt, it is possible to change the gear ratio steplessly and transmit the rotation of the input shaft to the output shaft. .

  In such a continuously variable transmission, the gear ratio is automatically controlled based on a throttle opening and a parameter indicating an operating state such as a vehicle speed or an engine speed. Specifically, based on the above parameters, the target primary pulley rotation speed is set by referring to the basic speed change characteristic map, and the gear ratio is set so that the actual primary pulley rotation speed converges to the target primary rotation speed. I am doing so.

  According to the basic shift characteristic map, the gear ratio is set to a higher speed as the throttle opening is smaller. Therefore, when the driver releases the accelerator pedal when traveling downhill, the throttle opening becomes smaller, the gear ratio is set to the high speed side, and the target input speed decreases, so the engine brake is controlled so that it does not work. become.

  Therefore, when the inertial pedal is released with the accelerator pedal released, that is, when the vehicle is traveling on a downhill road instead of a flat road, the gear ratio is downshifted to the low speed side and the engine speed or primary speed is reduced. The gear ratio is controlled so as to apply the engine brake by correcting the number so as to increase the number.

  For example, in the continuously variable transmission disclosed in Patent Document 1, the target deceleration is corrected by correcting the characteristic for setting the target deceleration depending on whether or not the brake operation is performed at the initial stage of inertial traveling. It tries to converge to the value.

  Further, when traveling on a downhill road, control is performed such that the lower limit value of the target input rotational speed is set to be larger than that when traveling on a flat road according to an increase in the absolute value of the weight gradient resistance. However, in this case, the acceleration when the accelerator pedal is depressed during inertia traveling on a downhill road is greater than the acceleration when the accelerator pedal is depressed during inertia traveling on a flat road, and the driver feels uncomfortable. Will have.

  Therefore, as disclosed in Patent Document 2, when the accelerator pedal is depressed while the vehicle is traveling downhill, the target input rotational speed is gradually changed at a predetermined rate of change so that a rapid gear ratio is obtained. Technologies that prevent fluctuations have been proposed.

  In the technique described in Patent Document 2, when the accelerator pedal is depressed during inertia traveling on a downhill road, the minimum value or the normal speed control target rotation speed table is set so that the correction amount of the engine brake becomes a predetermined change rate. Control is performed such that the rotational speed gradually decreases toward the lower limit rotational speed set by a one-dimensional table corresponding to the vehicle speed.

  In this way, if the engine speed is reduced again and the engine brake is required, if the engine speed is reduced at a predetermined rate of change until the lower limit engine speed is reached, regardless of the degree of acceleration or the accelerator pedal depression state. Therefore, it is necessary to return to the control for applying the engine brake from a rotational speed lower than necessary, and the engine brake cannot be applied immediately.

  Also, changes in driving force and engine braking force vary depending on the vehicle speed even at the same rotation speed, so if the gear ratio is controlled at a constant rate of change set in the low vehicle speed range, it may be uncomfortable at high vehicle speed ranges. is there.

  In order to cope with such a situation, the technique disclosed in Patent Document 3 detects the primary pulley when the vehicle is more than a predetermined acceleration / deceleration under the condition that the vehicle is traveling downhill. When the lower limit value of the target rotational speed for inertial travel is set and the inertial travel is canceled, the lower limit value is corrected based on the throttle opening and the vehicle speed under a predetermined acceleration / deceleration. Thus, the traveling performance is improved when the vehicle travels downhill on inertia.

  Incidentally, some vehicles equipped with a continuously variable transmission have a constant speed traveling control function (so-called cruise control control function).

Regarding control of a continuously variable transmission of a vehicle having such a constant speed traveling control function, for example, Patent Document 4 discloses a shift control at the time of constant speed traveling control according to a cruise signal from a constant speed traveling control device. There is a disclosure that the target primary pulley rotational speed is set according to any one of the map and the shift control map during normal travel.
JP-A-8-21500 JP-A-9-112682 JP 2003-83437 A JP-A-11-82717

  Equipped with a continuously variable transmission, switching control of the target primary pulley rotation speed lower limit is performed by determining whether the throttle opening of the throttle valve has reached the idle determination opening, and also has a constant speed running control function When the vehicle is running at a constant speed during a slow downhill or when the vehicle is light and has sufficient torque, the throttle opening of the throttle valve is determined to be the idle determination opening, that is, the idle determination is performed. You can drive in the vicinity.

  However, when the idle determination is made, the target primary pulley rotation speed increase / decrease value increases, the driving force changes, and the vehicle decelerates. Therefore, when the throttle valve is opened to correct the target vehicle speed, the idle determination is canceled, the target primary pulley rotation speed lower limit value is increased, and the driving force is changed. By repeating this, hunting at a short cycle of the vehicle speed occurs.

  The hunting of the vehicle speed with such a short cycle occurs as follows. (1) While the constant speed traveling control is not in operation, the above-mentioned idle determination is made based on the accelerator pedal opening degree. The same value as the target primary pulley rotation speed lower limit regardless of whether the above-mentioned idle determination is made based on the throttle opening of the throttle valve because the pedal is not depressed, and (2) regardless of whether the constant speed traveling control is activated or deactivated. Due to the use of

  The mechanism by which the hunting of the vehicle speed with a short cycle occurs will be described in detail with reference to FIG. This figure assumes constant speed traveling control on a downhill.

  Referring to FIG. 5, when constant speed traveling control is executed on a downhill, the vehicle speed is accelerated. Then, the throttle valve is closed to bring the vehicle speed closer to the control vehicle speed. At this time, it is determined whether or not the throttle opening of the throttle valve has reached the idle determination opening.

  When the throttle opening becomes the idle determination opening, the idle determination flag is turned on and the target primary pulley rotation speed lower limit is increased. As a result, the actual primary pulley rotation speed changes abruptly, and the change in driving force increases accordingly. As a result, the vehicle speed is suddenly reduced.

  When the vehicle speed becomes slower than the control vehicle speed, the throttle valve is opened to bring the vehicle speed closer to the control speed. At this time, it is determined whether or not the throttle opening of the throttle valve has reached the idle determination opening.

  When the throttle opening returns to the idling determination opening, the idling determination flag is turned off and the idling determination is canceled, so that the target primary pulley rotation speed lower limit value is lowered. Since this lowering range is large, the actual primary pulley rotation speed changes abruptly, and the change in driving force increases accordingly. As a result, the vehicle speed suddenly accelerates.

  By repeating such rapid deceleration and acceleration, short-cycle vehicle speed hunting occurs.

  Such short-cycle hunting of the vehicle speed gives the driver an uncomfortable feeling.

  The present invention has been made in view of the above technical problem, and is a continuously variable transmission that has a longer vehicle speed hunting cycle during constant speed traveling control, and thus does not give the driver a sense of incongruity during constant speed traveling control. The purpose is to provide a control device.

  A control device for a continuously variable transmission according to the present invention as viewed from a certain aspect is applied to a vehicle having a constant speed traveling control function, and includes a primary pulley on an input side and a secondary pulley on an output side that are paired with a variable groove width. , A control device for a continuously variable transmission comprising a transmission belt wound around the pair of primary pulleys and secondary pulleys to transmit power by frictional force, and the target rotational speed of the primary pulley during constant speed traveling control Lower limit value setting means for setting the lower limit value to a second value lower than the first value that is the target pulley speed lower limit value of the primary pulley when the constant speed running is not operated is included.

  The control device for the continuously variable transmission further includes idle determination means for determining whether or not the throttle opening of the throttle valve has reached an idle determination opening, and the lower limit setting means is controlled by the idle determination means. For setting the lower limit value of the target rotation speed of the primary pulley to the second value on the condition that the throttle opening of the throttle valve is determined to be the idle determination opening and that constant speed traveling control is being performed. Including means.

  A control device for a continuously variable transmission according to the present invention viewed from another aspect is applied to a vehicle having a constant-speed traveling control function, and a pair of input-side primary pulleys and output-side secondary pulleys having variable groove widths. And a continuously variable transmission control device that is wound around the pair of primary pulleys and secondary pulleys and transmits power by frictional force. A lower limit value storage means for storing a first value as a rotation speed lower limit value and storing a second value lower than the first value as a target rotation speed lower limit value of the primary pulley during constant speed traveling control; , An idle determination means for determining whether or not the throttle opening of the throttle valve has reached the idle determination opening, and the slot of the throttle valve by the idle determination means Lower limit value setting means for setting the target rotation speed lower limit value of the primary pulley to the second value on condition that the opening degree is determined to be the idle determination opening degree and the constant speed traveling control is being performed. Including.

  Under constant speed traveling control on a downhill road, the vehicle speed is repeatedly decelerated and accelerated so as to approach the control speed, but the change in driving force associated therewith is reduced.

  According to the present invention, the change in driving force under constant speed traveling control is reduced, and the vehicle speed hunting cycle during constant speed traveling control is lengthened. As a result, the driver does not feel uncomfortable during the constant speed traveling control.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a schematic configuration of a vehicle to which a control device for a continuously variable transmission according to an embodiment of the present invention is applied.

  The vehicle in the example shown in FIG. 1 is an FF (front engine / front drive) type vehicle, and has a constant speed traveling control (cruise control) function. The vehicle includes an engine 1, a torque converter 2, a forward / reverse switching device 3, a belt-type continuously variable transmission (CVT) 4, a reduction gear device 5, a differential gear device 6, and an ECU (Electronic Control Unit) shown in FIG. 8 etc. are installed.

  A crankshaft 11, which is an output shaft of the engine 1, is connected to the torque converter 2, and the output of the engine 1 is transmitted from the torque converter 2 to the forward / reverse switching device 3, the belt type continuously variable transmission 4, and the reduction gear device 5. To the differential gear device 6 and distributed to the left and right drive wheels 7L, 7R.

<Engine>
The engine 1 is, for example, a multi-cylinder gasoline engine. The intake air amount sucked into the engine 1 is adjusted by an electronically controlled throttle valve 12.

  The throttle valve 12 can electronically control the throttle opening independently of the driver's accelerator pedal operation, and the throttle opening is detected by the throttle opening sensor 102. Further, the coolant temperature of the engine 1 is detected by a water temperature sensor 103.

  The throttle opening of the throttle valve 12 is driven and controlled by the ECU 8. Specifically, the optimum intake air amount (in accordance with the operating state of the engine 1 such as the engine speed NE detected by the engine speed sensor 101 and the accelerator pedal depression amount (accelerator operation amount Acc) of the driver ( The throttle opening of the throttle valve 12 is controlled so as to obtain a target intake air amount. More specifically, the actual throttle opening of the throttle valve 12 is detected using the throttle opening sensor 102, and the actual throttle opening coincides with the throttle opening (target throttle opening) at which the target intake air amount can be obtained. Thus, the throttle motor 13 of the throttle valve 12 is feedback-controlled.

<Torque converter>
The torque converter 2 includes an input-side pump impeller 21, an output-side turbine runner 22, a stator 23 that exhibits a torque amplification function, and the like. Power is transmitted between the pump impeller 21 and the turbine runner 22 via fluid. Communicate.

  The pump impeller 21 is connected to the crankshaft 11 of the engine 1. On the other hand, the turbine runner 22 is connected to the forward / reverse switching device 3 via the turbine shaft 28.

  The torque converter 2 is provided with a lockup clutch 24 that directly connects the input side and the output side of the torque converter 2.

The lock-up clutch 24 has a differential pressure between the hydraulic pressure in the engagement-side oil chamber 25 and the hydraulic pressure in the release-side oil chamber 26 (lock-up differential pressure = hydraulic pressure P _ON in the engagement-side oil chamber 25−release-side oil chamber. By controlling the hydraulic pressure P _OFF in the interior 26, full engagement / half engagement (engagement in the slip state) or release is performed.

  By completely engaging the lockup clutch 24, the pump impeller 21 and the turbine runner 22 rotate integrally. Further, by engaging the lockup clutch 24 in a predetermined slip state (half-engaged state), the turbine runner 22 rotates following the pump impeller 21 with a predetermined slip amount during driving. On the other hand, by setting the lockup differential pressure to be negative, the lockup clutch 24 is released. The torque converter 2 is provided with a mechanical oil pump 27 that is connected to and driven by the pump impeller 21.

<Forward / backward switching device>
The forward / reverse switching device 3 includes a double pinion type planetary gear mechanism 30, a forward clutch C1, and a reverse brake B1.

  The sun gear 31 of the planetary gear mechanism 30 is integrally connected to the turbine shaft 28 of the torque converter 2, and the carrier 33 is integrally connected to the input shaft 40 of the belt type continuously variable transmission 4. The carrier 33 and the sun gear 31 are selectively coupled via a forward clutch C1, and the ring gear 32 is selectively fixed to the housing via a reverse brake B1.

  The forward clutch C1 and the reverse brake B1 are hydraulic friction engagement elements that are engaged and released by the hydraulic control circuit 20 shown in FIG. 2, and the forward clutch C1 is engaged, and the reverse brake B1 is By being released, the forward / reverse switching device 3 is in an integrally rotating state to establish a forward power transmission path, and in this state, the forward driving force is transmitted to the belt type continuously variable transmission 4 side. On the other hand, when the reverse brake B1 is engaged and the forward clutch C1 is released, the forward / reverse switching device 3 establishes a reverse power transmission path. In this state, the input shaft 40 rotates in the reverse direction with respect to the turbine shaft 28, and the driving force in the reverse direction is transmitted to the belt type continuously variable transmission 4 side. Further, when both the forward clutch C1 and the reverse brake B1 are released, the forward / reverse switching device 3 is in a neutral state (blocking state) for blocking power transmission.

<Belt type continuously variable transmission>
The belt type continuously variable transmission 4 includes an input-side primary pulley 41, an output-side secondary pulley 42, a metal transmission belt 43 wound around the primary pulley 41 and the secondary pulley 42, and the like.

  The primary pulley 41 is a variable pulley having a variable effective diameter, and a fixed sheave 411 fixed to the input shaft 40 and a movable sheave 412 disposed on the input shaft 40 in a state in which sliding is possible only in the axial direction. And is composed of. Similarly to the primary pulley 41, the secondary pulley 42 is a variable pulley whose effective diameter is variable, and a fixed sheave 421 that is fixed to the output shaft 44 and a sliding in the axial direction of the output shaft 44 is possible. And a movable sheave 422 arranged in a state.

  A hydraulic actuator 413 for changing the V groove width between the fixed sheave 411 and the movable sheave 412 is disposed on the movable sheave 412 side of the primary pulley 41. Similarly, a hydraulic actuator 423 for changing the V groove width between the fixed sheave 421 and the movable sheave 422 is also arranged on the movable sheave 422 side of the secondary pulley 42.

  In the belt-type continuously variable transmission 4 having the above-described structure, by controlling the hydraulic pressure of the hydraulic actuator 413 of the primary pulley 41, the widths of the V grooves of the primary pulley 41 and the secondary pulley 42 change, and the contact diameter of the transmission belt 43 changes. (Effective diameter) is changed, and the gear ratio γ (speed ratio γ = input shaft speed Nin / output shaft speed Nout) changes continuously. The hydraulic pressure of the hydraulic actuator 423 of the secondary pulley 42 is controlled so that the transmission belt 43 is clamped with a predetermined clamping pressure that does not cause belt slip. These controls are executed by the ECU 8 and the hydraulic control circuit 20.

  Although not particularly shown, the hydraulic control circuit 20 is provided with a linear solenoid valve, an on-off solenoid valve, and the like. By switching the hydraulic circuit by controlling excitation and de-excitation of these solenoid valves, a belt type continuously variable Shift control of the transmission 4 and engagement / release control of the lockup clutch 24 are performed. Excitation / non-excitation of the linear solenoid valve and the on / off solenoid valve of the hydraulic control circuit 20 is controlled by a solenoid control signal (instructed hydraulic signal) from the ECU 8.

<ECU>
FIG. 2 is a block diagram showing the configuration of the ECU.

  Referring to FIG. 2, ECU 8 includes CPU 81, ROM 82, RAM 83, backup RAM 84, and the like.

  The CPU 81 governs the control center of the ECU 8, and executes arithmetic processing based on various control programs and maps stored in the ROM 82.

  The ROM 82 stores various control programs, maps that are referred to when the various control programs are executed, and the like.

  The RAM 83 is a memory that temporarily stores calculation results in the CPU 81, data input from each sensor, and the like. The backup RAM 84 is a non-volatile memory that stores data to be saved when the engine 1 is stopped. .

  In the present embodiment, in particular, a predetermined storage area of RAM 83 stores first value A as the target rotation speed lower limit value of primary pool 41 when constant speed running is not performed, and during constant speed running control. A second value B lower than the first value A is stored as the target rotation speed lower limit value of the primary pulley 41. Note that when the first value A and the second value B are fixed values, they may be stored in the ROM 82.

  The CPU 81, ROM 82, RAM 83, and backup RAM 84 are connected to each other via a bus 87 and are connected to an input interface 85 and an output interface 86.

The input interface 85 of the ECU 8 includes an engine speed sensor 101, a throttle opening sensor 102, a water temperature sensor 103, a turbine speed sensor 104, an input shaft speed sensor 105, a vehicle speed sensor 106, an accelerator opening sensor 107, and a CVT oil temperature. A sensor 108, a brake pedal sensor 109, a lever position sensor 110 that detects a lever position (operation position) of the shift lever 9, a constant speed traveling control device 111, and the like are connected. An output signal of the travel control device 111 is given. Specifically, the rotational speed NE of the engine 1, the throttle opening θth of the throttle valve 12, the coolant temperature Tw of the engine 1, the rotational speed NT of the turbine shaft 28, the rotational speed Nin of the input shaft 40, the vehicle speed V, the accelerator pedal, etc. The amount of operation of the accelerator operation member (accelerator degree of engagement) Acc, the oil temperature of the hydraulic control circuit 20 (CVT oil temperature Thc), the presence or absence of operation of the foot brake as a service brake (brake ON / OFF), and the shift lever 9 lever position (operating position), as well as signals such as cruising signal S _CR of cruise control device 111 is supplied to the ECU 8.

  On the other hand, the throttle motor 13, the fuel injection device 14, the ignition device 15, the hydraulic control circuit 20, and the like are connected to the output interface 86 of the ECU 8.

  Here, of the signals supplied to the ECU 8, the turbine rotational speed NT coincides with the input shaft rotational speed Nin during forward travel where the forward clutch C1 of the forward / reverse switching device 3 is engaged, and the vehicle speed V is a belt type. This corresponds to the rotational speed (output shaft rotational speed) Nout of the output shaft 44 of the continuously variable transmission 4. The accelerator operation amount Acc represents the driver's requested output amount.

  The shift lever 9 includes a parking position “P” for parking, a reverse position “R” for reverse travel, a neutral position “N” for interrupting power transmission, a drive position “D” for forward travel, and a forward travel It is selectively operated to each position such as a manual position “M” where the speed ratio γ of the belt-type continuously variable transmission 4 can be increased or decreased manually during traveling.

  The manual position “M” includes a plurality of range positions in which a downshift position and an upshift position for increasing / decreasing the speed ratio γ, or a plurality of speed ranges in which the upper limit of the speed range (the side where the speed ratio γ is smaller) are different can be selected. Etc. are provided.

  The lever position sensor 110 may be, for example, a parking position “P”, a reverse position “R”, a neutral position “N”, a drive position “D”, a manual position “M”, an upshift position, a downshift position, or a range position. And a plurality of ON / OFF switches for detecting that the shift lever 9 is operated. In order to change the gear ratio γ manually, a downshift switch, an upshift switch, or a lever can be provided on the steering wheel or the like separately from the shift lever 9.

  The ECU 8 controls the output of the engine 1, the shift control of the belt type continuously variable transmission 4, the belt clamping pressure control, and the engagement / release of the lockup clutch 24 based on the output signals of the various sensors described above. Execute control.

  Output control of the engine 1 is performed by the throttle motor 13, the fuel injection device 14, the ignition device 15, the ECU 8, and the like. Shift control of the belt-type continuously variable transmission 4, belt clamping pressure control, and engagement of the lockup clutch 24. The release control is performed by the hydraulic control circuit 20 in all cases. The throttle motor 13, the fuel injection device 14, the ignition device 15, and the hydraulic pressure control circuit 20 are controlled by the ECU 8.

<Target primary pulley rotation speed lower limit setting routine>
FIG. 3 is a flowchart showing the contents of a target primary pulley rotation speed lower limit setting routine.

  Referring to FIG. 3, in setting the target rotational speed lower limit value of primary pulley 41 (hereinafter referred to as “target primary pulley rotational speed lower limit value”), first, based on the output signal from throttle opening sensor 102, The CPU 81 in the ECU 8 determines whether or not the throttle opening θth of the throttle valve 12 has reached the idle determination opening. In this determination, if it is determined that the throttle opening θth has reached the idle determination opening, that is, the idle determination is made, the CPU 81 turns on the idle determination flag. This idle determination flag ON state is held in the RAM 83.

  In step S1, the CPU 81 in the ECU 8 accesses the RAM 83 to determine whether or not the idle determination flag is in an ON state. If the idle determination flag is not in the ON state, the routine is temporarily exited. On the other hand, when the idle determination flag is in the ON state, the CPU 81 shifts the processing to step S2.

After the transition to step S2, based on the cruising signal S _CR from the constant speed control device 110, CPU 81 in ECU8 the traveling state is determined whether cruise control in. If there is no input of the cruise signal S _CR from cruise control unit 111, CPU 81 determines that not the cruise control in, CPU 81 is the target primary pulley rotational speed limit value by referring to the RAM83 Is set to the higher first value A (step S4), and the process is temporarily exited from this routine. On the other hand, when the idle determination flag is in the ON state, the CPU 81 refers to the RAM 83 and sets the target primary pulley rotation speed lower limit value to the lower second value B (step S3). Thereafter, the routine is temporarily exited.

<Target primary pulley speed lower limit setting operation>
FIG. 4 is a timing chart regarding the setting operation of the target primary pulley rotation speed lower limit value during the constant speed traveling control. This figure assumes constant speed traveling control on a downhill.

  Referring to FIG. 4, when constant speed traveling control is executed on a downhill, the vehicle speed is accelerated. Then, the throttle valve 12 is closed to bring the vehicle speed closer to the control vehicle speed. At this time, it is determined whether or not the throttle opening θth of the throttle valve 12 has reached the idle determination opening.

  When the throttle opening θth becomes the idle determination opening, the idle determination flag is turned ON, and the target primary pulley rotation speed lower limit is set to a second value B lower than the first value A. As a result, the actual primary pulley rotational speed changes gently, and the change in driving force is reduced accordingly. As a result, the vehicle speed slowly decreases.

  When the vehicle speed becomes slower than the control vehicle speed, the throttle valve 12 is opened to bring the vehicle speed closer to the control speed. At this time, it is determined whether or not the throttle opening θth of the throttle valve 12 has reached the idle determination opening.

  When the throttle opening θth returns to the idling determination opening, the idling determination flag is turned off and the idling determination is canceled, so that the target primary pulley rotation speed lower limit value is lowered. Since the amount of this decrease is small, the actual primary pulley rotational speed changes gently, and the change in driving force is reduced accordingly. As a result, the vehicle speed accelerates gradually.

  Thus, although deceleration and acceleration are repeated, the hunting cycle of the vehicle speed becomes longer than in the case of FIG.

<Action and effect>
According to the present embodiment, the following operations and effects are achieved.

  The second lower target primary pulley rotational speed lower limit value is lower than the first value A on condition that the throttle opening degree θth of the throttle valve 12 is determined to be the idle determination opening degree and the constant speed traveling control is being performed. Therefore, the change in the driving force under the constant speed traveling control is reduced. Therefore, the hunting cycle of the vehicle speed during the constant speed traveling control becomes longer. As a result, the driver does not feel uncomfortable during the constant speed traveling control.

  Note that the present invention is not limited to the above-described embodiment, and various design changes and modifications can be made within the scope of the appended claims.

1 is a diagram showing a schematic configuration of a vehicle to which a control device for a continuously variable transmission according to an embodiment of the present invention is applied. It is a block diagram which shows the structure of ECU. It is a flowchart which shows the content of the target primary pulley rotation speed lower limit setting routine. It is a timing chart regarding the setting operation of the target primary pulley rotation speed lower limit during the constant speed traveling control. It is a timing chart regarding the setting operation | movement of the target primary pulley rotation speed lower limit during the conventional constant speed running control.

Explanation of symbols

4 Belt type continuously variable transmission 41 Primary pulley 42 Secondary pulley 43 Transmission belt 8 ECU
81 CPU
82 ROM
83 RAM
101 Throttle opening sensor 111 Constant speed traveling control device

Claims (3)

Applied to a vehicle having a constant speed traveling control function, the input side primary pulley and the output side secondary pulley having a variable groove width and a pair, and the pair of primary pulleys and the secondary pulleys are wound on the power by friction force. A continuously variable transmission control device comprising a transmission belt for transmission,
A lower limit value for setting the target rotation speed lower limit value of the primary pulley during the constant speed traveling control to a second value lower than the first value that is the target rotation speed lower limit value of the primary pulley when the constant speed traveling operation is not performed. A control device for a continuously variable transmission, comprising setting means. The control device for a continuously variable transmission according to claim 1,
It further includes idle determination means for determining whether the throttle opening of the throttle valve has become an idle determination opening,
The lower limit value setting means is a lower limit of the target rotation speed of the primary pulley on the condition that the throttle opening degree of the throttle valve is determined to be the idle determination opening degree and the constant speed running control is being performed by the idle determination means. A control device for a continuously variable transmission, comprising means for setting a value to the second value. Applied to a vehicle having a constant speed traveling control function, the input side primary pulley and the output side secondary pulley having a variable groove width and a pair, and the pair of primary pulleys and the secondary pulleys are wound on the power by friction force. A continuously variable transmission control device comprising a transmission belt for transmission,
The first value is stored as the target rotational speed lower limit value of the primary pulley when the constant speed traveling is not operated, and the second value lower than the first value is set as the target rotational speed lower limit value of the primary pulley during the constant speed traveling control. Lower limit storage means for storing a value;
Idle determination means for determining whether or not the throttle opening of the throttle valve has reached the idle determination opening;
The target rotation speed lower limit of the primary pulley is set to the second value on condition that the throttle opening of the throttle valve is determined to be the idle determination opening by the idle determination means and the constant speed traveling control is being performed. A control device for a continuously variable transmission, comprising lower limit value setting means for setting.

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