JP4432436B2 - Shift control device for continuously variable transmission - Google Patents

Description

  The present invention relates to a speed change control device for controlling the speed ratio of a continuously variable transmission mounted on a vehicle or for controlling the rotational speed of a power source by a continuously variable transmission.

  As is well known, an internal combustion engine used as a power source for a vehicle has an output characteristic in which torque increases as the rotational speed increases up to a certain high rotational speed. On the other hand, the drive torque required for the vehicle may increase at low vehicle speeds, such as when starting or climbing. Therefore, if the transmission is placed on the output side of the internal combustion engine and the accelerator pedal is depressed when starting, accelerating, or climbing, and a large driving force is required, or if such a driving situation occurs, automatic The gear ratio is increased by manual or manual operation to increase the drive torque. On the other hand, when the vehicle is traveling on a flat road at medium and high speeds, the speed ratio is reduced to reduce the rotational speed of the internal combustion engine. On the other hand, at the time of deceleration, the transmission ratio is increased to increase the engine braking force.

  Recently, continuously variable transmissions have attracted attention as transmissions for vehicles. That is, according to the continuously variable transmission, the rotational speed of the internal combustion engine can be changed steplessly by continuously changing the gear ratio. Recently, it has become possible to electrically control the throttle opening, fuel supply amount, and the like. Therefore, for example, by setting the rotational speed arbitrarily by means of a continuously variable transmission while electrically controlling the throttle opening, it is possible to perform an operation in which the demand for driving force is satisfied and at the same time the fuel efficiency is optimized.

  Therefore, the transmission ratio of the automatic transmission for vehicles including the continuously variable transmission basically includes the required driving amount represented by the accelerator opening degree and the driving state of the internal combustion engine represented by the vehicle speed, the output shaft rotational speed, etc. Controlled based on In that case, a smaller gear ratio is set as the vehicle speed increases and the accelerator position decreases. On the other hand, when the engine brake is applied, it is necessary to rotate the internal combustion engine at a relatively high rotational speed. Therefore, even when the accelerator opening is as small as zero, a relatively large gear ratio is obtained. Is set.

  One example thereof is described in Patent Document 1. In the invention described in Patent Document 1, the rotational speed of an engine to which a continuously variable transmission is connected is feedback-controlled to a target rotational speed obtained based on a required drive amount and a vehicle speed in a normal traveling state, When the operation of (2) is detected and the deceleration is larger than the reference deceleration, the feedback control is stopped. This is because when the vehicle speed is not reduced when switching from the deceleration state to the acceleration state, the engine speed rapidly increases and a shock occurs, so that feedback control is stopped and the gear ratio is not increased. .

When controlling the continuously variable transmission, when the stepped manual transmission mode is selected, the feedforward control is executed by temporarily outputting a gear ratio change signal having an operation amount larger than the feedback control. The configured control device is described in Patent Document 2.
Japanese Patent Laid-Open No. 10-311422 JP 2001-208185 A

  In the invention described in the above-mentioned Patent Document 1, since the speed ratio is maintained at the conventional speed ratio at the time of so-called sudden deceleration, when the accelerator pedal is depressed immediately after the brake operation is performed and the deceleration becomes large. Can prevent the engine speed from blowing up, but on the other hand, since the gear ratio is kept small, the engine braking force becomes relatively small. In other words, engine braking is less effective.

  In addition, when the difference between the target engine speed and the actual engine speed increases in a region where the deceleration does not exceed the reference deceleration, feedback control is performed with the difference in the engine speed as the control deviation, so that a rapid shift is possible. And as a result, shock can occur.

  The present invention has been made paying attention to the above technical problem, and provides a speed change control device that can apply a prime mover brake according to deceleration and can prevent a shock regardless of the magnitude of deceleration. It is intended to do.

  In order to achieve the above object, according to the first aspect of the present invention, a continuously variable transmission is connected to the output side of a power source, and the continuously variable transmission is set so that the output rotational speed of the power source becomes a target rotational speed. In the continuously variable transmission control device for controlling the speed, when the deceleration determining means for determining the deceleration and the deceleration determined by the deceleration determining means are large, the target rotational speed is increased stepwise. And a sudden deceleration control execution means for executing rapid deceleration control for increasing at a predetermined gradient and further decreasing at a predetermined decrease gradient based on the requested deceleration. It is a control device.

  According to a second aspect of the present invention, the deceleration-time control execution means according to the first aspect of the invention determines the stepwise target rotational speed increase amount and the increase gradient after the stepwise increase as the deceleration determination means. A speed change control device comprising means for changing the speed according to the deceleration determined in (1).

  Further, the invention according to claim 3 is characterized in that the deceleration-time control execution means in the invention according to claim 2 compares the increase amount when the deceleration determined by the deceleration determination means is large, compared with when it is small. The shift control device includes means for setting a smaller value.

  According to a fourth aspect of the present invention, there is provided the invention according to any one of the first to third aspects, further comprising means for feedback control of the rotational speed of the power source based on a deviation between the target rotational speed and the actual rotational speed. A speed change control device characterized by the above.

  According to the first aspect of the present invention, when it is determined that the required deceleration is large or the deceleration is increased by performing a brake operation suddenly or greatly, the power is The target value for the number of revolutions of the source is increased in a stepwise manner after being increased stepwise, and then decreased with a predetermined gradient based on the required deceleration. As a result, the speed ratio of the continuously variable transmission is controlled so as to achieve the target rotational speed, so that the power source can generate a braking force and a so-called engine braking force can be applied. In that case, since no other operation such as manual shifting operation is required, drivability or driving operability can be improved.

  According to the invention of claim 2, since the target rotational speed to be increased stepwise and the subsequent increase gradient differ depending on the deceleration, the rotational speed of the power source follows the decreasing gradient of the target rotational speed based on the deceleration. In the case where the rotational speed decreases, the rate of change in the rotational speed can be appropriately controlled. For example, as described in claim 3, when the required deceleration is large, the increase gradient of the actual rotational speed becomes relatively gentle by reducing the stepwise increase amount of the target rotational speed. As a result, the change in the rotational speed when the actual rotational speed starts to decrease with a relatively steep decrease gradient based on the deceleration becomes relatively slow. Therefore, the inertial force resulting from the change in the rotational speed, the torque due to the twist of the drive system, and the like are reduced, and the shock can be effectively prevented or suppressed.

  According to the invention of claim 4, by controlling the target rotational speed as described above, even if the rotational speed of the power source is feedback-controlled, so-called engine braking can be applied without deteriorating the shock. Can do.

  Next, an embodiment of the present invention will be described with reference to the drawings. First, a power train of a vehicle to which the present invention can be applied and a control system of the vehicle are shown in FIG. In the vehicle Ve shown in FIG. 3, a fluid transmission device 3, a lockup clutch 4, a forward / reverse switching mechanism 5, a continuously variable transmission 6, and the like are provided on a power transmission path between the power source 1 and the wheels 2. Yes. As the power source 1, for example, at least one of an internal combustion engine or an electric motor can be used, and preferably an internal combustion engine having a mechanism capable of electrically controlling output such as an internal combustion engine having an electronic throttle valve is used. . As the electric motor, it is possible to use a motor generator having a power running function for converting electrical energy into kinetic energy and a regeneration function for converting kinetic energy into electrical energy. In this embodiment, a case where an internal combustion engine such as a gasoline engine, a diesel engine, or a natural gas engine is mainly used as the power source 1 will be described.

  Further, the fluid transmission device 3 and the lockup clutch 4 are provided in a power transmission path between the power source 1 and the forward / reverse switching mechanism 5, and the fluid transmission device 3 and the lockup clutch 4 are in parallel with each other. Has been placed. The fluid transmission device 3 is a device that transmits power by the kinetic energy of the fluid, and the lockup clutch 4 is a device that transmits power by a frictional force. The forward / reverse switching mechanism 5 is a device that selectively switches the rotation direction of the output member relative to the input member.

  The continuously variable transmission 6 is basically a mechanism capable of continuously changing the gear ratio, and a belt-type or toroidal-type continuously variable transmission can be used. FIG. 3 shows a belt type, and the continuously variable transmission 6 is provided in a power transmission path between the forward / reverse switching mechanism 5 and the wheels 2. More specifically, the continuously variable transmission 6 is provided with a primary shaft 7 and a secondary shaft 8 arranged in parallel to each other. The primary shaft 7 is provided with a primary pulley 9, and the secondary shaft 8 is provided with a secondary pulley 10. The primary pulley 9 has a fixed sheave 11 fixed to the primary shaft 7 and a movable sheave 12 configured to be movable in the axial direction of the primary shaft 7. A groove M <b> 1 is formed between the fixed sheave 11 and the movable sheave 12.

  Further, a hydraulic servo mechanism 13 is provided for moving the movable sheave 12 in the axial direction of the primary shaft 7 so that the movable sheave 12 and the fixed sheave 11 approach and separate from each other. The hydraulic servo mechanism 13 includes a hydraulic chamber 19 and a piston (not shown) that operates in the axial direction of the primary shaft 7 according to the oil amount or hydraulic pressure of the hydraulic chamber 19 and is connected to the movable sheave 12. Yes.

  On the other hand, the secondary pulley 10 has a fixed sheave 14 fixed to the secondary shaft 8 and a movable sheave 15 configured to be movable in the axial direction of the secondary shaft 8. A V-shaped groove M <b> 2 is formed between the fixed sheave 14 and the movable sheave 15. The belt 17 is wound around the pulleys 9 and 10 while being sandwiched between the grooves M1 and M2.

  In addition, a hydraulic servo mechanism 16 is provided that moves the movable sheave 15 in the axial direction of the secondary shaft 8 to bring the movable sheave 15 and the fixed sheave 14 closer to or away from each other. The hydraulic servo mechanism 16 includes a hydraulic chamber 100 and a piston (not shown) that operates in the axial direction of the secondary shaft 8 according to the hydraulic pressure or the oil amount of the hydraulic chamber 100 and is connected to the movable sheave 15. Yes.

  On the other hand, a hydraulic control device 18 having a function of controlling the hydraulic servo mechanisms 13 and 16 and the lockup clutch 4 and the forward / reverse switching mechanism 5 of the continuously variable transmission 6 is provided. Furthermore, an electronic control device 52 as a controller for controlling the power source 1, the lockup clutch 4, the forward / reverse switching mechanism 5, the continuously variable transmission 6, and the hydraulic control device 18 is provided. An arithmetic processing unit (CPU or MPU), a storage unit (RAM and ROM), and a microcomputer mainly including an input / output interface are included.

  For this electronic control unit 52, engine speed, accelerator pedal operation state, brake pedal operation state, throttle valve opening, shift position, primary shaft 7 rotation speed, secondary shaft 8 rotation speed, hydraulic pressure Sensor signals for detecting whether or not the solenoid valve of the control device 18 has failed, the intake air amount of the engine, and whether or not the road is uphill are input. The vehicle speed is obtained based on the rotational speed of the secondary shaft 8. Various types of data are stored in the electronic control unit 52. Based on the signal input to the electronic control unit 52 and the stored data, a signal for controlling the power source 1 is sent from the electronic control unit 52. A signal for controlling the step transmission 6, a signal for controlling the forward / reverse switching mechanism 5, a signal for controlling the lockup clutch 4, a signal for controlling the hydraulic control device 18, and the like are output.

  Data stored in the electronic control unit 52 includes a transmission control map, a lockup clutch control map, and the like. This transmission control map includes a gear ratio control map, a torque capacity control map, and the like. The transmission ratio control map is a map for setting the transmission ratio of the continuously variable transmission 6 or the target rotational speed of the power source 1 based on the vehicle speed, the accelerator opening, the deceleration, or the operating state of the brake. When an engine is used as the power source 1, the engine speed can be controlled to approach the optimum fuel consumption curve by controlling the speed ratio of the continuously variable transmission 6. This rotational speed control is mainly performed by feedback control based on the deviation between the target rotational speed and the actual rotational speed, and feedforward control is executed or used together as necessary. The torque capacity control map is a map used when controlling the torque capacity of the continuously variable transmission 6 based on a gear ratio, torque to be transmitted, and the like. The lockup clutch control map is a map for setting the torque capacity of the lockup clutch 4 based on the vehicle speed, the accelerator opening, and the like.

  As described above, the continuously variable transmission 6 can function so as to control the rotational speed of the power source 1 to the rotational speed at which the fuel efficiency is optimized. In this so-called normal control, for example, the required driving force is obtained from an appropriate map based on the required driving amount represented by the accelerator opening and the vehicle speed, and the target output of the power source is calculated from the required driving force and the vehicle speed. Is calculated. The target rotational speed at which the target output can be output with the optimum fuel efficiency is obtained from a map etc. as the rotational speed at the intersection of the so-called optimal fuel efficiency line and the target output line, and the target rotational speed and the actual power source rotational speed The gear ratio of the continuously variable transmission 6 is feedback controlled by controlling the difference. On the other hand, a target torque is calculated based on the target output and the vehicle speed at that time, and the output torque of the power source 1 is controlled by an electronic throttle valve or the like so as to achieve the target torque.

  In this so-called normal control, the continuously variable transmission 6 is controlled based on the traveling state determined by the vehicle speed, the turbine rotational speed of the fluid transmission device 3 and the required driving amount such as the accelerator opening. As control of the gear ratio of the machine 6, control based on manual operation is also possible. For example, when a shift device (not shown) is provided with an upshift switch and a downshift switch, and one of these switches is turned on by a shift lever or the like, the control is output from the on-operated switch. On the basis of this signal, the target rotational speed of the power source 1 is changed stepwise, or the target rotational speed is continuously changed while the signal is output. Such control may be referred to as manual shift control, for example.

  When manual shift control is performed in the downshift direction by turning on the downshift switch, the gear ratio set by the continuously variable transmission 6 increases. Therefore, the drive is activated in the accelerator-on state when the accelerator pedal is depressed. On the other hand, the torque increases and the acceleration performance increases. On the contrary, in the accelerator-off state, the driving torque in the negative direction increases, so the engine braking force (power source braking force) increases.

  The shift control device of the present invention executes such so-called manual shift control (sudden deceleration control in the present invention) without using a signal based on manual operation, and the control content of the manual shift control is different in the deceleration state. It is configured to let you. FIG. 1 is a flowchart for explaining an example of control executed by the speed change control apparatus according to the present invention. This routine is repeatedly executed every predetermined short time. First, it is determined whether or not the automatic downshift is performed when the brake is on (step S1). When a brake pedal (not shown) is depressed, a brake-on signal is output.However, if the amount of depression of the brake pedal is large or the depression speed is fast, there are other conditions such as the vehicle speed exceeding a predetermined value. As a result, the automatic downshift determination is established. In other words, since the accelerator is off when the brake is on, the normal shift control will cause an upshift when the required drive amount is reduced or zero. If the speed decreases, the gear ratio needs to be increased in preparation for subsequent re-acceleration. Therefore, it is necessary to perform the automatic downshift described above.

  If the determination in step S1 is negative, the routine of FIG. 1 is temporarily terminated without performing any particular control. On the other hand, if a positive determination is made in step S1, it is determined whether or not the downshift is manual shift control (step S2). That is, when the amount of depression of the brake pedal or the depression speed exceeds a predetermined reference value and the required deceleration is large or the deceleration actually generated by the brake operation is large, affirmative determination is made in step S1. At the same time, it is determined that it is necessary to apply the engine brake in the same manner as the downshift based on the manual operation, and the determination of manual shift control is established. That is, a positive determination is made in step S2. In that case, the process proceeds to step S3. If a negative determination is made in step S2, this routine is temporarily terminated without performing any particular control.

  In step S3, it is determined whether or not the control of the manual shift control for which the determination in step S2 is satisfied is started. In other words, it is determined whether the determination to execute the manual shift control is established or whether the manual shift control has already been started. Immediately after the brake pedal is suddenly depressed at a predetermined vehicle speed or higher, an affirmative determination is made in step S3. In this case, a step amount NINTMNLSTP (rpm) that increases the target rotational speed NINT of the power source 1 stepwise is obtained (step S4).

  The step amount NINTMNLSTP is an amount based on the deceleration. Therefore, the step amount NINTMNLSTP can be calculated based on the required deceleration obtained from the depression amount or the depression speed of the brake pedal or the actual deceleration, but more specifically. Is obtained from a predetermined map using the deceleration as an argument. The step amount NINTMNLSTP is set to a smaller value when the deceleration is large than when the deceleration is small. The step amount NINTMNLSTP determined in this way is added to the previous value NINT (i-1) to determine the current target rotational speed NINT (i) (step S5). Thereafter, this routine is temporarily terminated.

  When the routine of FIG. 1 is executed again after a predetermined short time has elapsed, the determination of manual shift control has already been established, so a negative determination is made in step S3 described above. In this case, a shift speed (increasing gradient of the target rotational speed) NINTMNL (rpm / sec) for gradually increasing the target rotational speed NINT is obtained (step S6). This is because the rotational speed of the power source 1 (the input rotational speed of the continuously variable transmission 6) is rapidly increased by increasing the target rotational speed NINT stepwise, and then the rotational speed is reduced according to the deceleration. This is for performing control to smooth the change immediately before the transition. Specifically, the shift speed NINTMNL is obtained from a predetermined map using the requested deceleration as an argument. It may be obtained by calculation.

  Then, the shift speed NINTMNL is set to a smaller value when the deceleration is large than when the deceleration is small. The shift speed NINTMNL obtained in this way is determined as an amount to increase the target rotational speed NINT every time the routine of FIG. 1 is executed once, and is therefore added to the previous value NINT (i-1). Thus, the current target rotational speed NINT (i) is obtained (step S7). Thereafter, this routine is temporarily terminated.

  The speed change control device according to the present invention controls the continuously variable transmission 6 by feedback control based on the target speed NINT obtained as described above and the actual speed. FIG. 2 schematically shows a change in the input rotation speed (or the rotation speed of the power source 1) of the continuously variable transmission 6 when the manual shift control is executed in a state where the deceleration is small and a large state. . First, the case where the deceleration is small will be described. Since the speed of the vehicle starts to decrease as the brake is turned on, the input rotational speed also starts to decrease. When the start of manual shift control is determined based on the degree of braking operation and the running state at that time, the target rotational speed NINT indicated by the broken line in FIG. 2 is increased stepwise. The step amount NINTMNLSTP is obtained according to the deceleration. Subsequently, the target rotational speed NINT is increased at a predetermined shift speed (gradient) NINTMNL with the target rotational speed increased stepwise as a base point.

  Therefore, at the start of manual shift control or immediately after that, the control deviation becomes the largest, so that the gear ratio of the continuously variable transmission 6 is controlled so as to increase the input rotational speed rapidly. On the other hand, when the target rotational speed NINT reaches a predetermined value determined in accordance with the vehicle speed or the requested deceleration, the target rotational speed NINT is decreased with a gradient in accordance with the deceleration request. Therefore, when the target rotational speed NINT increased with a predetermined increase gradient by manual shift control reaches the target value based on the deceleration request, the target rotational speed NINT is gradually decreased. For this reason, the actual input rotational speed increased with an increase in the target value coincides with the target rotational speed NINT in the course of the increase, and thereafter, the input rotational speed decreases substantially in accordance with the target rotational speed NINT.

  In that case, the actual input rotational speed is suddenly increased by manual shift control, and the increase gradient becomes large. However, since the decrease gradient based on the subsequent deceleration request is relatively gentle, the change in the rotational speed is The degree of change in the actual input rotational speed in the process (the region circled in FIG. 2) becomes smooth or slow, and as a result, shocks due to inertia torque or torsion of the drive system can be prevented or suppressed. . Further, in the above control, since the gear ratio of the continuously variable transmission 6 is increased, the engine brake can be applied and the operation can be automatically performed without manual operation. Or driving operability is improved.

  On the other hand, when the deceleration is relatively large, the step amount NINTMNLSTP by the manual shift control becomes relatively small, and the subsequent shift speed becomes moderate. Therefore, the increase gradient of the actual input rotation speed by feedback control becomes gentle compared to the case where the deceleration described above is small. For this reason, when the actual input rotational speed starts to decrease in accordance with the target rotational speed decreasing gradient determined based on the required deceleration and the vehicle speed (the region circled in FIG. 2), the required deceleration is large. As a result, although the decrease gradient is large, the increase gradient of the input rotation speed immediately before that is relatively gentle, so that the change from the increase of the input rotation speed to the decrease becomes smooth or gentle. Therefore, similarly to the case where the deceleration described above is small, it is possible to prevent or suppress a shock due to inertia torque, torsion of the drive system, or the like. Further, since the gear ratio of the continuously variable transmission 6 is increased, the engine brake can be applied and the operation can be automatically performed without manual operation. Will improve.

  Here, the relationship between the above-described specific example and the present invention will be briefly described. The functional means of step S1 described above corresponds to the deceleration determination means of the present invention, and the functional means of steps S2 to S7 are the same. This corresponds to the sudden deceleration control execution means of the present invention.

It is a flowchart for demonstrating the example of control by the transmission control apparatus of this invention. It is a time chart corresponding to the control example of FIG. It is a conceptual diagram which shows the power train and control system of the vehicle which can apply the control apparatus of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Power source, 6 ... Continuously variable transmission, 52 ... Electronic control apparatus.

Claims (4)

In the continuously variable transmission shift control device for controlling the continuously variable transmission such that the continuously variable transmission is connected to the output side of the power source and the output rotational speed of the power source becomes the target rotational speed.
Deceleration determining means for determining deceleration;
When the deceleration determined by the deceleration determination means is large, the target rotational speed is increased stepwise, then increased with a predetermined gradient, and further with a predetermined decrease gradient based on the required deceleration. A speed change control device for a continuously variable transmission, comprising: control execution means for sudden deceleration that executes control for sudden deceleration to be reduced.   The deceleration-time control execution means includes means for varying the stepwise target rotational speed increase amount and the increase gradient after the stepwise increase according to the deceleration determined by the deceleration determination means. The transmission control device for a continuously variable transmission according to claim 1.   3. The deceleration control execution means includes means for setting the increase amount smaller when the deceleration determined by the deceleration determination means is large than when it is small. A transmission control device for a continuously variable transmission according to claim 1.   4. The continuously variable transmission according to claim 1, further comprising means for feedback-controlling the rotational speed of the power source based on a deviation between the target rotational speed and the actual rotational speed. Gear shift control device.

Images