JP2012225417A - Shift control device of continuously variable transmission for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a shock and the occurrence of deceleration G beyond an intention, when a large power source brake is suddenly caused, when fixing the gear ratio in accelerator return operation.SOLUTION: When a belt type continuously variable transmission 18 is fixed to the fixed gear ratio γs, after upshifting the transmission 18 so as to decrease an input rotating speed Nin to a gear ratio fixed input rotating speed Nins corresponding to the fixed gear ratio γs (P1→P2 shifting), the transmission 18 is fixed to the fixed gear ratio γs (arrow b). Thus, an engine rotating speed NE decreases by an upshift amount as compared with a case where a gear ratio γ just before the accelerator return operation is maintained as it is (arrow c), an engine brake is reduced, and the occurrence of the deceleration G beyond the intention of a driver is restrained. Inertia in the driving direction is generated as the engine rotating speed NE decreases by an upshift, the engine brake is alleviated (offset), and the shock is restrained.

Description

  The present invention relates to a shift control device for a continuously variable transmission for a vehicle, and more particularly to shift control when an accelerator is returned.

  (a) a continuously variable transmission coupled to a power source; (b) a shift control means for controlling a gear ratio of the continuously variable transmission based on an accelerator operation amount; and (c) the accelerator by the shift control means. A transmission control device for a continuously variable transmission for a vehicle has been proposed, which includes a transmission ratio fixing means for fixing a transmission ratio of the continuously variable transmission in preference to a transmission control based on an operation amount. The device described in Patent Document 1 is an example, and when the accelerator return speed is equal to or higher than a predetermined value, it is determined that the driver intends to decelerate, and the gear ratio immediately before the accelerator is returned is unchanged. By maintaining it, a predetermined power source brake can be obtained (see paragraphs 27, 28, etc.).

JP 2003-74682 A

  However, if the speed ratio immediately before the accelerator is returned in this way is maintained as it is, a large power source brake is suddenly generated along with the accelerator return operation, causing a shock or a deceleration G higher than intended by the driver. Could occur.

  The present invention has been made against the background of the above circumstances. The purpose of the present invention is to suddenly generate a large power source brake when the speed ratio of the continuously variable transmission is fixed at the time of the accelerator return operation. Thus, it is possible to prevent a shock from occurring or a deceleration G more than intended.

  In order to achieve such an object, the first invention includes (a) a continuously variable transmission coupled to a power source, and (b) a shift control for controlling a gear ratio of the continuously variable transmission based on an accelerator operation amount. Shifting of the continuously variable transmission for a vehicle including: (c) speed ratio fixing means for fixing the speed ratio of the continuously variable transmission in preference to the speed change control based on the accelerator operation amount by the speed change control means. In the control device, (d) when the accelerator is returned, the speed ratio fixing means upshifts to a fixed speed ratio smaller than the immediately previous speed ratio.

  According to a second aspect of the present invention, there is provided (a) a continuously variable transmission connected to a power source, and (b) the continuously variable transmission based on the accelerator operation amount so that the gear ratio becomes smaller as the accelerator operation amount is smaller. Gear change control means for controlling the gear ratio; (c) deceleration intention determination means for determining whether or not the driver intends to decelerate when the accelerator is returned; and (d) deceleration by the deceleration intention determination means. A gear ratio fixing means for fixing the gear ratio of the continuously variable transmission in preference to the gear shift control based on the accelerator operation amount by the gear shift control means. (E) In the transmission control device for a continuously variable transmission for a vehicle that generates a predetermined power source brake by fixing the transmission ratio of the continuously variable transmission by the transmission ratio fixing means, (f) the transmission ratio The fixing means is a speed change immediately before the accelerator is returned. Is set to a predetermined fixed speed ratio that is smaller than the speed ratio by the speed change control of the speed change control means based on the accelerator operation amount after the accelerator is returned, and upshifted to the fixed speed ratio. The fixed gear ratio is maintained.

  According to a third aspect of the present invention, in the transmission control device for a continuously variable transmission for a vehicle according to the first or second aspect of the invention, the fixed speed ratio has a decrease width with respect to the speed ratio immediately before the accelerator is returned, The continuously variable transmission is set based on the input rotational speed so that the input rotational speed of the continuously variable transmission immediately before the return operation is higher than when it is low.

  According to a fourth aspect of the present invention, in the shift control device for a continuously variable transmission for a vehicle according to the second aspect of the present invention, the deceleration intention determination means is in a predetermined accelerator operation state even after the accelerator is operated to return, If the change amount of the accelerator operation amount and the change amount of the vehicle speed are each equal to or less than a predetermined deceleration intention determination value, it is determined that the driver intends steady driving with a substantially constant vehicle speed. When at least one of the change amount of the accelerator operation amount and the change amount of the vehicle speed after the operation exceeds the deceleration intention determination value, it is determined that the driver intends the deceleration.

  In the shift control device for a continuously variable transmission for a vehicle according to the first aspect of the invention, when the speed ratio is fixed during the accelerator return operation, the upshift is performed to a predetermined fixed speed ratio that is smaller than the speed ratio immediately before the accelerator return operation. Compared with the case where the gear ratio immediately before the accelerator returning operation is maintained as it is, the rotational speed of the power source becomes lower by the amount of upshift, the power source brake is reduced, and the deceleration G more than intended by the driver is generated. Is suppressed. In addition, since inertia in the driving direction occurs due to a change (decrease) in the rotational speed of the power source due to the upshift, the power source brake is relaxed (offset) by the amount of the inertia, and the shock is suppressed.

  In the shift control device for a continuously variable transmission for a vehicle according to the second aspect of the present invention, when determining the driver's intention to decelerate and fixing the gear ratio during the accelerator return operation, the gear ratio is smaller than the gear ratio immediately before the accelerator return operation, In addition, a predetermined fixed speed ratio larger than the speed ratio by the speed change control of the speed change control means based on the accelerator operation amount after the accelerator return operation is set, and the continuously variable transmission is upshifted to the fixed speed ratio and the fixed speed change ratio is increased. Maintain ratio. In other words, the second invention substantially corresponds to one embodiment of the first invention, and as in the first invention, the power source is increased by an amount corresponding to the upshift as compared with the case where the gear ratio immediately before the accelerator returning operation is maintained. , The power source brake is reduced, and the occurrence of deceleration G that is greater than intended by the driver is suppressed. In addition, since inertia in the driving direction occurs due to a change (decrease) in the rotational speed of the power source due to the upshift, the power source brake is relaxed (offset) by the amount of the inertia, and the shock is suppressed.

  In the third aspect of the present invention, the input rotation speed is such that the reduction width of the fixed speed ratio with respect to the speed ratio immediately before the accelerator return operation is larger than the low speed when the input rotational speed of the continuously variable transmission immediately before the accelerator return operation is high. The fixed gear ratio is set based on the speed, but the higher the input rotational speed, the higher the rotational speed of the power source, and a large power source brake is generated when the accelerator is returned. By setting the fixed gear ratio according to the rotational speed, it is possible to appropriately suppress the occurrence of a shock caused by a sudden increase in the power source brake and the undesired deceleration G regardless of the difference in the input rotational speed, A predetermined power source brake can be generated.

  According to a fourth aspect of the present invention, when at least one of the change amount of the accelerator operation amount and the change amount of the vehicle speed after the accelerator return operation exceeds a deceleration intention determination value even in a predetermined accelerator operation state after the accelerator is returned. The driver determines that the vehicle intends to decelerate, and the gear ratio is fixed to a predetermined fixed gear ratio based on the intention to decelerate, so that a predetermined power source brake is generated. It becomes possible to more appropriately determine whether the driver intends to decelerate or steady running, and power source brake control that further matches the driver's intention is performed.

1 is a skeleton diagram illustrating a vehicle drive device to which the present invention is applied. It is a block diagram explaining the principal part of the control system with which the vehicle drive device of FIG. 1 is provided. It is a functional block diagram explaining the principal part of the function with which the electronic controller of FIG. 2 is provided regarding the shift control of a belt-type continuously variable transmission. It is a figure explaining an example of the shift map used when calculating | requiring the target rotational speed Nint in the shift control of a belt-type continuously variable transmission. FIG. 4 is a flowchart for specifically explaining the processing contents of an accelerator return shift control means of FIG. 3. FIG. It is a flowchart explaining the steady travel intention determination process performed by the deceleration intention determination means of FIG. FIG. 6 is a diagram for explaining an example of changes in the input rotation speed Nin, the target rotation speed Nint, and the accelerator operation amount Acc when the accelerator return shift control is performed according to the flowchart of FIG. Chart (b) is a time chart when intended for steady driving.

  As a continuously variable transmission, for example, a belt type continuously variable transmission in which a transmission belt is wound around a pair of variable pulleys is widely used. In general, the width of a primary variable pulley on the input side is controlled to change the speed. However, it is possible to change the speed by controlling the groove width of the output side secondary variable pulley, and it is also possible to adopt another continuously variable transmission such as a toroidal type.

  The shift control means for controlling the speed ratio γ (= input rotation speed Nin / output rotation speed Nout) of the continuously variable transmission is, for example, a shift map determined by using the driver's output request amount such as the accelerator operation amount and the vehicle speed as parameters. The target rotational speed Nint is calculated in accordance with the shift conditions such as, and the shift control is performed so that the input rotational speed Nin becomes the target rotational speed Nint. The speed ratio γ is [input rotational speed Nin / output rotational speed Nout], and the output rotational speed Nout is determined by the vehicle speed. Therefore, the speed ratio γ can be controlled by controlling the input rotational speed Nin. The result is the same even if the transmission gear ratio γ itself is calculated according to the transmission conditions such as a transmission map and the input rotational speed Nin is controlled so as to be the transmission gear ratio γ.

  The present invention generates a predetermined power source brake by shift control when the accelerator is returned, and an engine (such as an internal combustion engine) that generates power by burning fuel is preferably used as the power source. A power source brake (engine brake) is obtained by the friction torque, pumping loss, etc. of the engine. However, even in an electric vehicle or a hybrid vehicle equipped with a rotating machine such as a motor generator as a power source, for example, the regenerative control ( The power source brake can be generated by performing power generation control. The continuously variable transmission shifts the rotation of the power source and transmits it to the drive wheel side, and the power source brake can be controlled by changing the rotational speed of the power source by shift control.

  The speed ratio fixing means only needs to upshift to a predetermined fixed speed ratio that is at least smaller than the speed ratio immediately before the accelerator is returned. In the second aspect, the speed ratio immediately before the accelerator is returned. And a fixed speed ratio that is smaller than the speed ratio by the speed change control of the speed change control means based on the amount of accelerator operation after the accelerator is operated to return to a predetermined power source brake. However, it is not always necessary to obtain the speed ratio by the speed change control of the speed change control means based on the accelerator operation amount after the accelerator return operation. As a result, a fixed speed ratio larger than the speed ratio may be set. This fixed gear ratio is compared when the input rotation speed of the continuously variable transmission is high immediately before the accelerator is returned, for example, as in the case of the third aspect of the invention. Is set based on the input rotation speed so as to increase, but it may be reduced only by a predetermined reduction range from the gear ratio immediately before the accelerator returning operation, or the sports mode, eco mode, etc. Various modes are possible, for example, the range of decrease can be switched according to the driving preference of the driver.

  Since the reduction range of the transmission ratio corresponds to the reduction range of the input rotation speed, the reduction range of the input rotation speed from the input rotation speed immediately before the accelerator return operation is the acceleration return instead of the reduction range of the transmission ratio itself. The fixed transmission gear ratio or the input rotational speed corresponding to the fixed transmission gear ratio may be set so that when the input rotational speed immediately before the operation is high, it becomes larger than when the input rotational speed is low. For example, when the input rotation speed immediately before the accelerator return operation is high, shift control is performed so that the decrease in the input rotation speed is larger than when the input rotation speed is low, or a predetermined constant is determined from the input rotation speed immediately before the accelerator return operation. The speed change control is performed so as to reduce the input rotation speed by the reduction width of the above, and the speed ratio determined according to the input speed after the reduction is maintained as the fixed speed ratio.

  When the gear ratio fixing means upshifts the belt type continuously variable transmission to the fixed gear ratio, the input rotation speed or the change rate or change pattern of the gear ratio can suppress excessive deceleration G by the upshift, and the rotation of the power source A constant rate of change or a constant change pattern may be set in advance so that a sudden increase in the power source brake can be suppressed by inertia due to speed change. It is also possible to set the driving state such as the reduction range), the vehicle speed, the input rotational speed immediately before the accelerator return operation, the accelerator operation amount after the accelerator return operation, and the like as parameters.

  The deceleration intention determination means of the second aspect of the present invention provides the driver with the driver when the accelerator is operated to return, for example, when at least one or both of the return amount and the return speed exceed a predetermined deceleration intention determination value. It is configured to determine that deceleration is intended. The return amount and return speed deceleration intention determination values may be set to predetermined values in advance, but the vehicle state immediately before the accelerator return operation, the output rotational speed Nout, the road surface gradient, the vehicle weight, and other vehicle conditions are set as parameters. May be. In the fourth aspect of the present invention, at least one of the change amount of the accelerator operation amount and the change amount of the vehicle speed after the accelerator return operation is determined in advance when the accelerator is in a predetermined accelerator operation state (accelerator ON) even after the accelerator is returned. When the decelerating intention determination value is exceeded, it is determined that the driver intends to decelerate. However, when other inventions are implemented, for example, the accelerator operation amount has been returned to the accelerator OFF (non-operating state) of 0. Various aspects are possible, for example, the intention to decelerate may be made on the condition of.

  In the fourth aspect of the invention, when the accelerator is ON even after the accelerator return operation and the change amount of the accelerator operation amount and the change amount of the vehicle speed after the accelerator return operation are respectively equal to or less than a predetermined deceleration intention determination value, the driver In this case, it is not necessary to generate a large power source brake by fixing the gear ratio. For example, the gear ratio is determined according to the normal gear shift control based on the accelerator operation amount by the gear shift control means. Should be controlled. The change amount of the accelerator operation amount and the change amount of the vehicle speed after the accelerator return operation may be the change amount with respect to the accelerator operation amount and the vehicle speed immediately after the accelerator return operation, but the driver intends the steady running. It is appropriate to determine whether or not the vehicle is operating based on the change amount of the accelerator operation amount or the change amount of the vehicle speed per predetermined time after the accelerator return operation. In addition, when the intention of steady travel is determined based on the accelerator operation amount after the accelerator return operation and the change amount of the vehicle speed in this way, the required time for the determination may become longer. Thus, it is desirable that the speed change control by the speed ratio fixing means be performed assuming that the intention is to decelerate until the steady travel intention determination is confirmed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a skeleton diagram illustrating the configuration of a vehicle drive device 10 to which the present invention is applied. The vehicle drive device 10 is suitably employed in an FF (front engine / front drive) type vehicle, and includes an engine 12 as a power source for traveling. The engine 12 is an internal combustion engine that generates power by combustion of fuel. The output of the engine 12 is from a torque converter 14 as a fluid transmission device to a forward / reverse switching device 16, a belt type continuously variable transmission (CVT) 18, It is transmitted to the differential gear device 22 via the reduction gear device 20 and distributed to the left and right drive wheels 24L, 24R.

  The torque converter 14 includes a pump impeller 14p connected to the crankshaft of the engine 12 and a turbine impeller 14t connected to the forward / reverse switching device 16 via a turbine shaft 34, and transmits power through a fluid. Is supposed to do. Further, a lockup clutch 26 is provided between the pump impeller 14p and the turbine impeller 14t, and an engagement side oil chamber is provided by a lockup control valve or the like in the hydraulic control circuit 90 (see FIG. 2). In addition, the hydraulic pressure supply to the release side oil chamber is switched to engage or release. For the pump impeller 14p, the belt type continuously variable transmission 18 is controlled to shift, the belt clamping pressure is generated, the lockup clutch 26 is engaged and released, or the lubricating oil is supplied to each part. A mechanical oil pump 28 that generates the hydraulic pressure is connected.

  The forward / reverse switching device 16 is mainly composed of a double pinion type planetary gear device, and the turbine shaft 34 of the torque converter 14 is integrally connected to the sun gear 16 s, and the input shaft 36 of the belt type continuously variable transmission 18. Is integrally connected to the carrier 16c, while the carrier 16c and the sun gear 16s are selectively connected via the forward clutch C1, and the ring gear 16r is selectively fixed to the housing via the reverse brake B1. It is like that. The forward clutch C1 and the reverse brake B1 correspond to a connection / disconnection device that connects and disconnects power transmission, and are both hydraulic friction engagement devices that are frictionally engaged by a hydraulic cylinder.

  When the forward clutch C1 is engaged and the reverse brake B1 is released, the forward / reverse switching device 16 is brought into an integral rotation state, the turbine shaft 34 is directly connected to the input shaft 36, and the forward power transmission path. Is established (achieved), and the driving force in the forward direction is transmitted to the belt-type continuously variable transmission 18 side. When the reverse brake B1 is engaged and the forward clutch C1 is released, the reverse power transmission path is established (achieved), and the input shaft 36 rotates in the reverse direction with respect to the turbine shaft 34. As a result, the driving force in the reverse direction is transmitted to the belt type continuously variable transmission 18 side. Further, when both the forward clutch C1 and the reverse brake B1 are released, the forward / reverse switching device 16 becomes neutral (interrupted state) for interrupting power transmission.

  The belt-type continuously variable transmission 18 is an input-side member provided on the input shaft 36 and is an output-side member provided on the output shaft 44 and a primary variable pulley 42 having a variable effective diameter, that is, a variable groove width. A secondary variable pulley 46 having a variable effective diameter, that is, a variable groove width, and a transmission belt 48 wound around the variable pulleys 42, 46 are provided, and the variable pulleys 42, 46 and the transmission belt 48 are Power is transmitted via the frictional force between them.

  The pair of variable pulleys 42 and 46 includes an input side fixed rotating body 42 a and an output side fixed rotating body 46 a fixed to the input shaft 36 and the output shaft 44, respectively, and relative to the input shaft 36 and the output shaft 44 about the axis. An input-side movable rotating body 42b and an output-side movable rotating body 46b that are provided so as to be non-rotatable and movable in the axial direction, and an input-side hydraulic cylinder 42c as a hydraulic actuator that applies thrust to change the V-groove width therebetween. And an output side hydraulic cylinder 46c. The primary hydraulic pressure PIN supplied to the input side hydraulic cylinder 42c is controlled by the hydraulic pressure control circuit 90, so that the V groove widths of the variable pulleys 42 and 46 change, and the engagement diameter (effective diameter) of the transmission belt 48 changes. Is changed, and the gear ratio γ (= input rotation speed Nin / output rotation speed Nout) is continuously changed. The input rotation speed Nin is the rotation speed of the input shaft 36, and the output rotation speed Nout is the rotation speed of the output shaft 44. Further, the pressure of the output side hydraulic cylinder 46c (secondary hydraulic pressure Pd) is controlled by the hydraulic control circuit 90, so that the belt clamping pressure is controlled so that the transmission belt 48 does not slip.

  FIG. 2 is a block diagram illustrating a main part of the control system provided in the vehicle drive device 10 of FIG. The electronic control unit 50 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM, and signals according to a program stored in the ROM in advance. By performing the processing, output control of the engine 12, shift control of the belt-type continuously variable transmission 18, belt clamping pressure control, torque capacity control of the lock-up clutch 26, and the like are executed. It is configured separately for engine control, for hydraulic control of the belt type continuously variable transmission 18 and the lockup clutch 26, and the like.

  The electronic control unit 50 includes a signal representing the rotational speed (engine rotational speed) NE of the engine 12 detected by the engine rotational speed sensor 52, and the rotational speed (turbine rotational speed) of the turbine shaft 34 detected by the turbine rotational speed sensor 54. ) A signal representing NT, a signal representing the input rotational speed (rotational speed of the input shaft 36) Nin of the belt-type continuously variable transmission 18 detected by the input rotational speed sensor 56, and a belt-type continuously variable detected by the vehicle speed sensor 58. An output rotational speed of the transmission 18 (rotational speed of the output shaft 44) Nout, that is, a signal representing a rotational speed corresponding to the vehicle speed V, provided in the intake pipe 32 (see FIG. 1) of the engine 12 detected by the throttle sensor 60. A throttle valve opening signal indicating the throttle valve opening θth of the electronic throttle valve 30, and an error detected by the coolant temperature sensor 62. A signal indicating the coolant temperature Tw of the engine 12, a signal indicating the hydraulic oil temperature (oil temperature) Tcvt of the belt-type continuously variable transmission 18 detected by the CVT oil temperature sensor 64, and the accelerator detected by the accelerator operation amount sensor 66 An accelerator operation amount signal indicating the accelerator operation amount Acc, which is the operation amount of the pedal 68, a brake operation signal indicating presence / absence Bon of the foot brake, which is a service brake detected by the foot brake switch 70, and a lever position sensor 72 are detected. An operation position signal indicating the lever position (operation position) Psh of the shift lever 74 is supplied.

  The shift lever 74 is disposed in the vicinity of the driver's seat, for example, and is one of five lever positions “P”, “R”, “N”, “D”, and “L” provided in order. To be manually operated. The “P” position is a neutral position (neutral state) in which the power transmission of the vehicle drive device 10 is interrupted, and a parking position (position) for mechanically preventing (locking) the rotation of the output shaft 44 by the mechanical parking mechanism. The “R” position is a reverse travel position (position) for reversing the rotation direction of the output shaft 44, and the “N” position is a neutral state in which the power transmission of the vehicle drive device 10 is interrupted. The “D” position is a forward travel position (position) that establishes an automatic transmission mode in which the belt-type continuously variable transmission 18 travels forward while automatically shifting. The position is the engine brake position where the belt-type continuously variable transmission 18 is held on the low gear side and a strong engine brake is generated. Is a position).

  On the other hand, the electronic control unit 50 controls the output of the engine 12, for example, a throttle signal for driving a throttle actuator 76 for controlling the opening / closing of the electronic throttle valve 30 and the amount of fuel injected from the fuel injection unit 78. An injection signal for controlling the ignition timing, an ignition timing signal for controlling the ignition timing of the engine 12 by the ignition device 80, and the like are output. In addition, a control signal for driving the linear solenoid valve SLP for shift control for controlling the primary hydraulic pressure PIN related to the gear ratio γ of the belt-type continuously variable transmission 18 and the secondary hydraulic pressure Pd related to the belt clamping pressure are set. A control signal for driving the clamping pressure control linear solenoid valve SLS for control is output, and the output hydraulic pressures Pslp and Psls are respectively controlled to predetermined hydraulic pressures. Further, a control signal for duty-controlling the excitation current of the ON-OFF solenoid valve DSU for controlling the lockup control valve for controlling the engagement release of the lockup clutch 26 is output, and the output hydraulic pressure Pdsu is controlled to a predetermined hydraulic pressure. To do.

  As shown in FIG. 3, the electronic control unit 50 functionally includes a shift control means 100 and an accelerator return shift control means 110 regarding the shift control of the belt-type continuously variable transmission 18, and the accelerator return shift control means 110. Further, a deceleration intention determination unit 112 and a gear ratio fixing unit 114 are functionally provided. The shift control means 100 shows the target rotation speed Nint of the input rotation speed Nin of the belt-type continuously variable transmission 18 in the forward automatic shift mode in which the shift lever 74 is operated to the “D” position, for example, as shown in FIG. Thus, the actual input rotational speed Nin matches the target rotational speed Nint by obtaining the accelerator operation amount Acc and the vehicle speed V from parameters as parameters and by performing feedback control of the linear solenoid valve SLP for shift control. The primary hydraulic pressure PIN is controlled so as to do this. Since the gear ratio γ is [input rotational speed Nin / output rotational speed Nout] and the output rotational speed Nout is constant in a short time corresponding to the vehicle speed V, the target rotational speed Nint is based on the vehicle speed V at that time. The speed ratio γ is substantially controlled to the target speed ratio by controlling the input speed Nin so as to coincide with the target speed Nint corresponding to the target speed ratio. The shift map of FIG. 4 shows that the ratio of the target rotational speed Nint to the vehicle speed V becomes smaller and the speed ratio γ becomes smaller as the accelerator operation amount Acc, that is, the driver's output request amount is smaller and the vehicle speed V is higher. It is stipulated in.

  The accelerator return shift control means 110 determines whether or not the driver intends to decelerate when the accelerator pedal 68 is returned during the forward travel in the automatic shift mode in which the shift lever 74 is operated to the “D” position. Accordingly, the deceleration intention determination means 112 is for determining whether or not the driver is performing an accelerator return operation intended for deceleration. The gear ratio fixing means 114 has a speed ratio γ prior to the speed change control based on the speed change map by the speed change control means 100 when the speed reduction intention determining means 112 determines that the speed reduction intention is intended. Is fixed at a relatively large fixed gear ratio γs, so that the engine 12 is maintained at a relatively high speed regardless of the accelerator return operation, and a relatively large engine brake is generated due to the friction torque, pumping loss, etc. of the engine 12 Let

  FIGS. 5 and 6 are flowcharts for specifically explaining the operation of the accelerator returning shift control means 110. Step S1 in FIG. 5 and steps Q1, Q2, and Q8 in FIG. 6 correspond to the deceleration intention determination means 112. 5 corresponds to the gear ratio fixing means 114. In step S1 of FIG. 5, it is determined whether or not a predetermined start condition regarding the accelerator return shift control is satisfied. If satisfied, step S2 and subsequent steps are executed. The start condition is, for example, that a return amount by a series of return operations of the accelerator pedal 68, that is, a decrease amount δAcc of the accelerator operation amount Acc exceeds a predetermined deceleration intention determination value DS1, and a return speed of the accelerator pedal 68, That is, the decrease speed dAcc of the accelerator operation amount Acc exceeds a predetermined deceleration intention determination value DS2. These deceleration intention determination values DS1 and DS2 may be set to predetermined values in advance, but the vehicle state such as the vehicle speed V, the output rotation speed Nout, the road surface gradient, the vehicle weight, etc. immediately before the accelerator return operation is set as a parameter. You may be made to do.

  In step S2, the execution determination of the shift control at the time of returning the accelerator is performed, and in step S3, a start command for the steady travel intention determination process is output based on the execution determination. The steady travel intention determination process is performed according to the flowchart of FIG. 6 and is performed in parallel with the signal processing of the accelerator return shift control according to the flowchart of FIG. In step Q1 of FIG. 6, it is determined whether or not a precondition for steady running determination is satisfied. The precondition for the steady running determination is that the accelerator pedal 68 after the accelerator returning operation is in the depressed state (accelerator ON), the foot brake switch 70 is in the non-depressed state (brake OFF), and the amount of accelerator operation per predetermined time. If the change amount ΔAcc of Acc is equal to or smaller than a predetermined deceleration intention determination value DS3, if all of them are satisfied, step Q2 and the subsequent steps are executed. Whether or not the accelerator is ON can be determined based on whether or not the accelerator operation amount Acc is greater than or equal to a predetermined value of substantially 0, but whether or not the idle signal of the throttle sensor 60 indicating that the opening of the electronic throttle valve 30 is in the idle range is OFF. Judgment can also be made. In addition, the deceleration intention determination value DS3 may be set to a predetermined value in advance, but may be set based on the driving state such as the accelerator operation amount Acc at that time, for example.

  If the determination in step Q1 is NO (negative), that is, if any one of the three preconditions is not satisfied, step Q7 is executed, and the content of the assumed normal travel determination counter C is cleared to zero. Subsequently, step Q8 is executed, and a deceleration intention determination is made to the effect that the driver intends to decelerate. Thereafter, step Q1 and subsequent steps are repeated.

  In step Q2, it is determined whether or not the change amount ΔV of the vehicle speed V per predetermined time continues for a predetermined time or more and is equal to or less than a predetermined deceleration intention determination value DS4. Step Q3 is executed. If NO (No), Steps Q7 and Q8 are executed and then Steps Q1 and after are repeated. The deceleration intention determination value DS4 may be a predetermined value in advance, but may be set based on the driving state such as the vehicle speed V at that time, for example. In step Q3, the assumed normal running determination is performed, and in step Q4, 1 is added to the assumed normal running determination counter C based on the assumed normal running determination. Further, in step Q5, it is determined whether or not the content of the assumed normal travel determination counter C is equal to or greater than a predetermined steady travel determination value Cs, and step C1 and subsequent steps are repeated while C <Cs. Then, when C ≧ Cs is reached, step Q6 is executed, and a steady traveling intention determination is performed to the effect that the driver intends steady traveling that travels at a substantially constant vehicle speed V. Thereafter, step Q1 and subsequent steps are repeated.

  When step Q6 or Q8 is executed once and the intention of steady running or deceleration is determined, the determination result is maintained until next step Q6 or Q8 is executed. In addition, while the accelerator return shift control in FIG. 5 is being executed (steps S4 to S7 are being executed), steps Q1 and after are repeatedly executed, and the change is made when the accelerator operation amount Acc or the vehicle speed V changes, or when the foot brake is turned ON / OFF Judgment is switched.

  Returning to FIG. 5, in step S4, it is determined whether or not the steady travel intention determination is performed in the steady travel intention determination process of FIG. 6. If the steady travel intention determination is made in step Q6, the process proceeds to step S5. Shift control at the time of steady running intention determination is executed. Further, when the steady running intention determination has not been made, that is, when the deceleration intention determination has been made at Step Q8 or when Steps Q1 to Q5 have been repeated and no intention determination has been made yet, Step The shift control at the time of the intention to decelerate in S6 is executed. Therefore, step S6 is executed at the beginning of the accelerator return shift control.

  As shown in FIG. 7A, the shift control at the time of the intention to decelerate in step S6 is such that the input rotational speed Nin is reduced to a predetermined speed ratio fixed input rotational speed Nins corresponding to the fixed speed ratio γs. Then, the belt type continuously variable transmission 18 is upshifted, and thereafter, the belt type continuously variable transmission 18 is controlled so as to maintain the fixed speed ratio γs after the upshift. The gear ratio fixed input rotational speed Nins is lower than the immediately preceding input rotational speed Nina immediately before the accelerator return operation, and is obtained from the shift map of FIG. 4 according to the accelerator operation amount Acc and the vehicle speed V after the accelerator return operation. In this embodiment, the decrease δNin with respect to the immediately preceding input rotation speed Nina is higher than the target rotation speed Nint. When the immediately preceding input rotation speed Nina is high, the immediately preceding input rotation speed Nina is larger than when it is low. Is set according to a predetermined map, arithmetic expression, or the like. For example, in the shift map of FIG. 4, when the accelerator return operation is performed from the state of the point P1 where the accelerator operation amount Acc is approximately 60% to approximately 20% or less, the target rotational speed Nint is determined by the belt type continuously variable transmission 18. The speed ratio γ decreases to the point P3 at which the minimum speed ratio γmin is reached, but the speed ratio fixed input rotational speed Nins is set to a point P2 lower than the point P1 by a predetermined decrease width δNin, and the actual input rotational speed Nin is An upshift is performed so as to obtain a fixed gear ratio input rotational speed Nins. The speed ratio γ determined according to the speed ratio fixed input speed Nins set based on the immediately preceding input speed Nina and the vehicle speed V (output speed Nout) at that time is the fixed speed ratio γs. The reduction width δNin relates to the input rotational speed Nin. The reduction width δNin corresponds to the reduction width from the speed ratio γ immediately before the accelerator return operation to the fixed speed ratio γs.

  The arrow b in FIG. 4 indicates that the input rotational speed Nin is decreased from the point P1 (immediately input rotational speed Nina) to the point P2 (speed ratio fixed input rotational speed Nins) by the upshift of the belt-type continuously variable transmission 18. The change of the input rotational speed Nin when the input rotational speed Nin is decreased as the vehicle speed V is decreased by maintaining the belt type continuously variable transmission 18 at a constant fixed speed ratio γs is shown. It is. At time t1 in FIG. 7 (a), the accelerator pedal 68 is returned and the determination in step S1 becomes YES, and the shift control at the time of returning the accelerator, specifically, the shift control at the intention of deceleration in step S6 is started. The time t2 is the time when the upshift for reducing the input rotational speed Nin to the fixed gear ratio input rotational speed Nins is completed. Further, after the time t2, the belt type continuously variable transmission 18 is fixed at a fixed fixed speed ratio γs, and the input rotational speed Nin is decreased according to the change in the vehicle speed V.

  In this way, the belt-type continuously variable transmission 18 is upshifted so that the input rotational speed Nin becomes a relatively high speed ratio fixed input rotational speed Nins, and then the belt-type continuously variable transmission 18 is kept at a fixed fixed speed. By maintaining the ratio γs, the input rotational speed Nin is maintained at a relatively high speed, and the engine 12 is maintained at a relatively high speed regardless of the accelerator return operation. A relatively large engine brake that matches the driver's intention to decelerate can be obtained by pumping loss or the like. In addition, since inertia in the driving direction is generated by a change in the rotational speed of the engine 12 due to the upshift (decrease from Nina to Nins), the engine brake is relaxed (offset) by the amount of the inertia, and the shock is suppressed.

  That is, as the speed change control at the time of the intention to decelerate, conventionally, the speed ratio γ at the point P1 immediately before the accelerator return operation is maintained as shown by the arrow c in FIG. There is a possibility that a large engine brake is suddenly generated and a shock occurs, or a deceleration G more than intended by the driver may occur. However, in this embodiment, the engine rotational speed NE is reduced by the upshift. Thus, the engine brake is reduced, the occurrence of a deceleration G that is greater than intended by the driver is suppressed, and a sudden increase in the engine brake is suppressed by the inertia in the driving direction of the engine 12 due to the upshift. The speed change speed and the decrease width δNin at the time of upshift that reduces the input rotational speed Nin from the immediately preceding input rotational speed Nina to the transmission ratio fixed input rotational speed Nins suppress the excessive deceleration G in this way and It is determined as appropriate so that a sudden increase in brake can be suppressed. For example, the shift speed (the rate of change of the input rotation speed Nin) and the decrease width δNin are determined based on the driving state such as the accelerator return speed (accelerator operation amount Acc decrease speed dAcc), the vehicle speed V, the accelerator operation amount Acc after the accelerator return operation. The input rotation speed Nin may be decreased at a predetermined change rate or change pattern that is set in advance regardless of the operating state.

  Returning to FIG. 5, in the next step S <b> 7, it is determined whether or not the input rotational speed Nin is substantially equal to the target rotational speed Nint. That is, the speed change map of FIG. 4 in which the target rotational speed Nint is set with the vehicle speed V and the accelerator operation amount Acc as parameters is basically determined so that the speed ratio γ increases as the vehicle speed V decreases. The input rotational speed Nin that is decreased as the vehicle speed V is decreased at a constant fixed speed ratio γs is made to coincide with the target rotational speed Nint at a predetermined timing before the vehicle speed V = 0. Then, step S4 and subsequent steps are repeatedly executed until Nin≈Nint. When the target rotational speed Nint is reached, the shift control end processing when the accelerator is returned is performed in step S8. In this ending process, the process shifts to the shift control by the shift control means 100 and the steady travel intention determination process of FIG. 6 is ended. A time t3 in FIG. 7A is a time when the input rotation speed Nin becomes equal to the target rotation speed Nint and the shift control at the time of returning the accelerator is completed. Even when the accelerator return shift control that repeats steps S4 to S7 is being executed, if a predetermined control end condition is satisfied, for example, the accelerator pedal 68 is depressed more than a predetermined amount, step S8 is immediately performed. The end process is performed.

  On the other hand, as shown in FIG. 7 (b), the shift control at the time of the determination of steady running intention in step S5 is performed by changing the input rotation speed Nin from the shift map of FIG. Shift control of the belt-type continuously variable transmission 18 is executed so as to gradually decrease to a target rotational speed Nint determined according to V. For example, in the shift map of FIG. 4, when the accelerator return operation is performed from the state of the point P1 where the accelerator operation amount Acc is approximately 60% to approximately 20% or less, the target rotational speed Nint is determined by the belt type continuously variable transmission 18. The speed ratio γ is set at a point P3 where the minimum speed ratio γmin is obtained. In that case, the gradual decrease of the input rotational speed Nin, that is, the shift speed of the belt-type continuously variable transmission 18 is abruptly upshifted, causing a sense of projecting in the driving direction due to the inertia of the engine 12, or large when the upshift is too slow. In order to prevent the occurrence of engine braking, for example, based on the deviation ΔNin up to the target rotational speed Nint, the accelerator return amount at the time of the accelerator return operation (a decrease amount δAcc of the accelerator operation amount Acc), etc. When the deviation ΔNin and the decrease amount δAcc are small, the change rate of the input rotational speed Nin is determined to be smaller than when it is large. It is also possible to set the change rate and change pattern of the input rotation speed Nin in consideration of other driving conditions such as the accelerator operation amount Acc and the vehicle speed V after the accelerator return operation.

  Thereafter, step S7 is executed to determine whether or not the input rotational speed Nin has reached the target rotational speed Nint. By repeatedly executing step S4 and subsequent steps until Nin≈Nint, the input rotational speed Nin is smoothly gradually reduced by the shift control (upshift) of the belt type continuously variable transmission 18, and when the target rotational speed Nint is reached, the step is performed. S8 is executed and the shift control at the time of returning the accelerator is terminated. The time t1 in FIG. 7B is the time when the accelerator pedal 68 is returned and the determination in step S1 is YES, and the shift control at the time of returning the accelerator is started, and the time t2 is the input rotational speed Nin. This is the time at which the shift control at the time of returning the accelerator is completed after reaching the target rotational speed Nint. FIG. 7B shows the shift control at the time of steady travel intention determination. Immediately after the start of the accelerator return shift control at time t1, the deceleration at step S6 is performed until the steady travel intention determination is made at step Q6. Shift control at the time of intention determination is performed. However, even in the shift control at the time of the intention to decelerate, the belt type continuously variable transmission 18 is upshifted at the beginning of the control and the input rotational speed Nin is lowered, so that the state shown in FIG. 4 indicates the change in the input rotational speed Nin when the input rotational speed Nin is decreased from the point P1 to the point P3 due to the upshift of the belt type continuously variable transmission 18 at the time of the above-described steady travel intention determination. It is shown.

  As described above, in this embodiment, when the driver's intention to decelerate is determined at the time of the accelerator returning operation and the belt type continuously variable transmission 18 is fixed at the fixed fixed gear ratio γs in step S6, immediately before the accelerator returning operation. A speed ratio fixed input speed Nins that is lower than the input speed Nina and higher than the target speed Nint obtained based on the accelerator operation amount Acc after the accelerator return operation is set, and the input speed Nin is set to the speed ratio. After the belt type continuously variable transmission 18 is upshifted so as to decrease to the fixed input rotation speed Nins (P1 → P2 shift in FIG. 4), the belt type is changed to the fixed transmission ratio γs corresponding to the transmission ratio fixed input rotation speed Nins. The gear ratio γ of the continuously variable transmission 18 is fixed (arrow b in FIG. 4). For this reason, the engine speed NE is reduced by the amount corresponding to the upshift compared with the case where the gear ratio γ immediately before the accelerator returning operation is maintained (arrow c in FIG. 4), and the engine brake is reduced and the driver intended. Occurrence of the above deceleration G is suppressed. Further, since inertia in the driving direction is generated due to a decrease in the engine rotational speed NE due to upshifting, the engine brake is relaxed (offset) by the amount of the inertia, and the shock is suppressed.

  Further, in this embodiment, the decrease width of the fixed speed ratio γs with respect to the speed ratio γ immediately before the accelerator returning operation, specifically, the decrease width δNin of the speed ratio fixed input rotation speed Nins with respect to the immediately preceding input rotation speed Nina is input immediately before that. The gear ratio fixed input rotation speed Nins (corresponding to the fixed gear ratio γs) is set based on the immediately preceding input rotation speed Nina so that the rotation speed Nina is higher than when it is low. The higher the Nina is, the higher the engine speed NE is, and a large engine brake is generated when the accelerator pedal 68 is returned. Therefore, the fixed gear ratio input rotational speed Nins is set according to the immediately preceding input rotational speed Nina. Appropriately generate a shock caused by a sudden increase in engine brake or a deceleration G higher than intended, regardless of the difference in the previous input rotational speed Nina A predetermined engine brake can be generated while being suppressed.

  Further, in this embodiment, even when the accelerator pedal 68 is operated to return to the predetermined accelerator operation state (accelerator ON), at least one of the change amount ΔAcc of the accelerator operation amount Acc and the change amount ΔV of the vehicle speed V is intended to decelerate. When the determination value DS3 or DS4 is exceeded, it is determined that the driver intends to decelerate, and based on the intention to decelerate, the shift control at the time of decelerating determination in step S6 is performed, and the belt type continuously variable transmission Since the predetermined engine brake is generated when 18 is fixed to the fixed speed ratio γs, it is more appropriately determined whether the driver intends to decelerate or steady driving when the accelerator pedal 68 is returned. This makes it possible to perform engine brake control that further matches the driver's intention.

  Further, in this embodiment, until the steady travel intention determination or the deceleration intention determination is performed in the steady travel intention determination process of FIG. 6, the shift control at the time of the deceleration intention determination in step S6 is performed. If the deceleration intention is determined at step Q8 while the engine is kept at a relatively high speed, the shift control at the time of the deceleration intention determination at step S6 is continued as it is, while the steady travel intention determination is performed at step Q6. In step S5, the process shifts to the shift control at the time of steady running intention determination, and the input rotational speed Nin is decreased. Therefore, the speed change control at the time of returning the accelerator is quickly started in accordance with the return operation of the accelerator pedal 68, and the input rotational speed Nin is lowered by the upshift of the belt type continuously variable transmission 18, and the input rotational speed Nin and the input The speed ratio γ determined according to the rotational speed Nin is prevented from fluctuating up and down depending on the determination result of the steady travel intention determination process of FIG. 6, and the input rotational speed Nin and the speed ratio γ are smooth regardless of any intention determination. Can be changed. However, this is not the case when the determination result of the steady travel intention determination process in FIG. 6 changes due to a change in the accelerator operation amount Acc or the like during the execution of the accelerator return shift control in steps S4 to S7.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention is implemented in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

  12: Engine (power source) 18: Belt type continuously variable transmission 50: Electronic control device 68: Accelerator pedal 100: Shift control means 110: Accelerator return speed change control means 112: Deceleration intention determination means 114: Gear ratio fixing means Acc : Accelerator operation amount Nin: Input rotation speed Nina: Previous input rotation speed (speed ratio immediately before accelerator return operation) Nins: Gear ratio fixed input rotation speed (fixed gear ratio) δNin: Decrease width

Claims (4)

A continuously variable transmission coupled to a power source;
Shift control means for controlling a gear ratio of the continuously variable transmission based on an accelerator operation amount;
Transmission ratio fixing means for fixing the transmission ratio of the continuously variable transmission in preference to the transmission control based on the accelerator operation amount by the transmission control means;
In a transmission control device for a continuously variable transmission for a vehicle having
The speed change control device for a continuously variable transmission for a vehicle, wherein the speed change ratio fixing means upshifts to a fixed speed change ratio smaller than a previous speed change ratio when the accelerator is returned. A continuously variable transmission coupled to a power source;
Shift control means for controlling the speed ratio of the continuously variable transmission based on the accelerator operation amount so that the speed change ratio decreases as the accelerator operation amount decreases
A deceleration intention determination means for determining whether or not the driver intends to decelerate when the accelerator is returned;
A speed ratio that fixes the speed ratio of the continuously variable transmission in preference to the speed change control based on the accelerator operation amount by the speed change control means when the speed reduction intention determination means determines that the speed reduction is intended. Fixing means;
A transmission control device for a continuously variable transmission for a vehicle that generates a power source brake by fixing the transmission ratio of the continuously variable transmission by the transmission ratio fixing means;
The speed ratio fixing means is smaller than a speed ratio immediately before the accelerator is operated to return, and is higher than a speed ratio by speed control of the speed control means based on an accelerator operation amount after the accelerator is operated to return. A shift control apparatus for a continuously variable transmission for a vehicle, wherein a large predetermined fixed gear ratio is set, and the fixed gear ratio is maintained by upshifting to the fixed gear ratio. The fixed speed ratio is larger than the low speed when the input rotational speed of the continuously variable transmission is high immediately before the accelerator is returned when the reduction ratio with respect to the speed ratio immediately before the accelerator is returned. Thus, the shift control device for a continuously variable transmission for a vehicle according to claim 1 or 2, wherein the shift control device is set based on the input rotation speed. The deceleration intention determination means is a deceleration intention determination value in which the change amount of the accelerator operation amount and the change amount of the vehicle speed after the accelerator return operation are respectively determined in advance in a predetermined accelerator operation state even after the accelerator is returned. In the following cases, it is determined that the driver intends steady driving with a substantially constant vehicle speed, but at least one of the change amount of the accelerator operation amount and the change amount of the vehicle speed after the accelerator return operation is the deceleration intention. The shift control apparatus for a continuously variable transmission for a vehicle according to claim 2, wherein when the determination value is exceeded, it is determined that the driver intends to decelerate.

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