JP4449165B2 - Shift control device for continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device for a continuously variable transmission mounted on a vehicle.
[0002]
[Prior art]
Conventionally, in Japanese Patent Laid-Open No. 2-72268, a torque converter with a lock-up clutch is provided in a power transmission path between a vehicle engine and a drive wheel, and a gear ratio is continuously set on the output shaft side of the torque converter. A vehicle provided with a continuously variable transmission (CVT) that can be changed is disclosed. In this vehicle, if the lockup clutch is engaged during vehicle deceleration, the rotation of the drive wheels is directly transmitted to the engine. Therefore, even if the engine is not operated, the engine rotation speed can be raised to the idle rotation speed or higher to maintain the rotation, and the fuel cut region can be expanded to improve the fuel consumption. Further, in a vehicle equipped with such a CVT, when the accelerator is at a low opening, the engine is operated by switching the gear ratio to the low-rotation high-gear side as much as possible to achieve a fuel-efficient driving. Therefore, when the vehicle decelerates, the CVT gear ratio is controlled so that the input rotational speed of the CVT becomes the minimum rotational speed at the vehicle speed at that time. In this way, the gear ratio is gradually increased when the vehicle decelerates, and the engine brake increases accordingly.
[0003]
[Problems to be solved by the invention]
By the way, in the above vehicle, when the vehicle is decelerating, the lower the CVT gear ratio, the lower the rotation speed of the CVT, the slower the CVT shift speed, and the CVT shift responsiveness and drive responsiveness deteriorate during reacceleration. Also, when the vehicle suddenly stops, the CVT transmission ratio returns to the low gear side. Therefore, if the vehicle is driven on the high-rotation low gear side and the lock-up clutch is engaged to a low vehicle speed, there is a problem that deceleration acceleration increases and drivability deteriorates.
[0004]
The present invention has been made in view of such circumstances, and an object of the present invention is to improve the shift response of the continuously variable transmission while avoiding the deterioration of drivability during vehicle deceleration. An object of the present invention is to provide a shift control device for a step transmission.
[0005]
[Means for Solving the Problems]
In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is connected to the input side or the output side of the clutch mechanism that is engaged when the vehicle is decelerated and connects the power transmission path between the prime mover and the drive wheels, and the input rotational speed on the prime mover side is In a continuously variable transmission shift control device that outputs continuously as an output rotational speed on the drive wheel side by shifting in a stepless manner, the target input rotational speed of the continuously variable transmission is the lowest rotational speed at the vehicle speed at the time of vehicle deceleration. with increased over, based on that the speed range from a first vehicle speed the vehicle speed at the time of vehicle deceleration engagement of the clutch mechanism is released to a second vehicle speed higher than the speed of the first said Setting means for setting the target input rotation speed so that the increase amount of the target input rotation speed gradually decreases as the vehicle speed decreases, and the input rotation speed of the continuously variable transmission becomes the target input rotation speed. Before And summarized in that a control means for controlling the gear ratio of the continuously variable transmission.
[0006]
Therefore, according to the first aspect of the invention, when the vehicle is decelerated, the target input rotational speed of the continuously variable transmission is increased from the minimum rotational speed at the vehicle speed at that time, so that the transmission ratio of the continuously variable transmission is It will be on the high rotation low gear side. Therefore, when the vehicle is re-accelerated, the shift response and drive response of the continuously variable transmission are improved, and the return performance of the gear ratio during sudden deceleration to the lowest gear side is improved. Further, since the increase amount of the target input rotational speed is set to be small at a vehicle speed near the first vehicle speed at which the clutch mechanism is released, the low gear of the continuously variable transmission when the clutch mechanism is engaged. As a result, it is possible to suppress a change in the speed ratio to the side, to reduce an increase in deceleration acceleration, and to suppress deterioration in drivability.
[0007]
According to a second aspect of the present invention, in the shift control device for a continuously variable transmission according to the first aspect, the setting means sets a third vehicle speed higher than the second vehicle speed during vehicle deceleration. The gist of the invention is to increase the target input rotational speed of the continuously variable transmission mechanism based on the fact that the speed is lower than the minimum rotational speed at the vehicle speed at that time.
[0008]
Therefore, according to the second aspect of the invention, when the vehicle is decelerated, the target input rotational speed of the continuously variable transmission mechanism is set to the lowest rotational speed at the vehicle speed until the vehicle speed falls below the third vehicle speed. Therefore, the gear ratio of the continuously variable transmission is on the high gear side, and the fuel-efficient driving is achieved.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which a control device for a vehicle equipped with a continuously variable transmission according to the present invention is embodied will be described in detail with reference to the drawings.
[0010]
FIG. 1 is a schematic configuration diagram illustrating a continuously variable transmission-equipped vehicle and a control device thereof according to the present embodiment. First, the configuration of a power transmission system that controls power transmission between the engine 10 as the prime mover and the drive wheels 17 in this vehicle will be described.
[0011]
As shown in FIG. 1, the output shaft 10 a of the engine 10 is connected to a torque converter 11. The torque converter 11 is a kind of a fluid joint that transmits the input rotation through a fluid (oil), and appropriately adjusts the rotational torque of the engine output shaft 10a by mediating the fluid to drive wheels 17. It communicates to the side.
[0012]
The torque converter 11 includes a lockup clutch mechanism 12. The lock-up clutch mechanism 12 operates based on hydraulic control by the hydraulic control circuit 19 and enables direct power transmission between the engine 10 side and the drive wheel 17 side of the torque converter 11.
[0013]
Further, the drive wheel 17 side of the torque converter 11 provided with such a lockup clutch mechanism 12 is connected to a forward / reverse switching mechanism 13 that reverses the direction of rotation input from the engine 10 side when the vehicle reverses, and further drives the torque converter 11. The wheel 17 side is connected to a continuously variable transmission (CVT) 14 for shifting. Accordingly, the output shaft of the engine 10 and the CVT 14 are directly connected by the engagement of the lockup clutch mechanism 12, and the connection between the engine 10 and the CVT 14 is disconnected by the disengagement of the lockup clutch mechanism 12.
[0014]
Then, the lock-up clutch mechanism 12 is operated to perform a so-called “lock-up” that allows direct power transmission between the engine 10 and the CVT 14 without mediating the fluid (oil) of the torque converter 11. I try to do it. By performing such a lock-up, it is possible to suitably avoid a reduction in power transmission efficiency due to fluid slip in the torque converter 11 and to improve the fuel consumption of the engine 10.
[0015]
The vehicle according to the present embodiment includes a drive pulley 14b and a driven pulley 14c that are drivingly connected by a belt 14a wound around each other as the CVT 14. The driving and driven pulleys 14b and 14c are configured so that the clamping width of the belt 14a can be changed by hydraulic pressure. Then, the transmission ratio is continuously changed by changing the clamping width of the belt 14a between the pulleys 14b and 14c and changing the winding radius of the belt 14a by hydraulic control by the hydraulic control circuit 19. Yes.
[0016]
Further, the drive wheel 17 side of the CVT 14 includes a speed reduction mechanism 15 that reduces and transmits rotation from the engine 10 side, and a differential (differential vehicle device) 16 that allows differential of the left and right drive wheels 17. It is connected to the drive wheel 17 via the via.
[0017]
In this way, power is transmitted between the engine 10 and the drive wheel 17 through the torque converter 11, the CVT 14, and the like including the lockup clutch mechanism 12.
[0018]
Next, in such a vehicle with a clutch mechanism, the configuration of a drive transmission system such as the lock-up clutch mechanism 12 and the CVT 14 and a control system that controls the engine 10 will be described with reference to FIG.
[0019]
In the vehicle according to the present embodiment, as an electronic control unit (ECU) that plays a role as the control system, an engine ECU (“E / G ECU”) 30 that mainly controls the operation of the engine 10, mainly the drive described above. A transmission ECU (“CVT ECU”) 31 that controls the transmission system is provided. Each of the ECUs 30 and 31 is electrically connected through an in-vehicle network line.
[0020]
Outputs of various sensors that detect the operating state of the vehicle and the engine 10 are input to the input ports of the ECUs 30 and 31, including the speed sensor 33 that detects the traveling speed (vehicle speed) of the vehicle. Furthermore, the outputs of various sensors that detect the operation state of the driver such as an accelerator sensor 35 that detects the amount of depression of the accelerator pedal 34 (accelerator depression amount) are also input to these input ports.
[0021]
On the other hand, the output ports of the ECUs 30 and 31 are connected to various actuators for controlling the engine 10, driving circuits for driving the hydraulic control circuit 19, and the like. The engine ECU 30 performs operation control of the engine 10 such as fuel injection based on the outputs of the various sensors. Further, the transmission ECU 31 controls the lockup clutch mechanism 12 and the like in addition to performing the shift control of the CVT 14 by drivingly controlling the hydraulic control circuit 19.
[0022]
Next, various control modes of the transmission ECU 31 during vehicle deceleration will be described in detail with reference to FIGS.
As described above, if the lockup clutch mechanism 12 is engaged during deceleration of the vehicle, power is directly transmitted from the drive wheels 17 to the engine 10 side, and the engine rotation can be performed without operating the engine 10. The speed is increased above the idle rotation speed and the rotation is maintained. Therefore, when performing the fuel cut during deceleration of the vehicle, if the lock-up clutch mechanism 12 is engaged, the fuel cut region can be expanded and the fuel efficiency can be improved.
[0023]
In particular, in a vehicle equipped with the CVT 14 as in the present embodiment, it is possible to change gears while the lock-up clutch mechanism 12 is operated. Therefore, the engagement of the lock-up clutch mechanism 12 during vehicle deceleration over a longer period of time. It is possible to further expand the fuel cut region.
[0024]
When the accelerator pedal 34 is turned off and the vehicle is decelerated, the fuel cut of the engine 10 is performed and the lockup clutch mechanism 12 is engaged and operated to expand the fuel cut region. .
[0025]
On the other hand, when the vehicle speed is low in the deceleration state of the vehicle, the transmission ratio of the CVT 14 is set to the low gear side in order to ensure power performance during reacceleration.
Further, in the control device for a continuously variable transmission-equipped vehicle according to the present embodiment, as shown in FIG. 4, a vehicle speed (lock-up OFF vehicle speed) V0 at which the lock-up clutch mechanism 12 is unlocked is set and the vehicle is decelerated. When the vehicle speed falls below the vehicle speed V0, the lockup clutch mechanism 12 is disengaged. Thus, before the deceleration acceleration of the vehicle becomes excessive, the drivability is prevented from being deteriorated by releasing the direct drive connection between the engine 10 side and the drive wheel 17 side of the vehicle.
[0026]
Hereinafter, a setting mode of the target input rotation speed of the CVT 14 for performing the transmission ratio control of the CVT 14 at the time of vehicle deceleration in the present embodiment will be described.
FIG. 2 is a flowchart showing a processing procedure of a “target input rotation speed setting routine” for setting such a target input rotation speed. This routine is periodically executed by the transmission ECU 31 at predetermined time intervals.
[0027]
When the processing shifts to this routine, the transmission ECU 31 first calculates a basic target input rotation speed at step 110. This basic target input rotation speed is calculated based on the driving state of the vehicle such as the accelerator depression amount and the vehicle speed, and is calculated as a higher value as the accelerator depression amount increases and as the vehicle speed increases. The basic target input rotation speed is set as low as possible when the accelerator depression amount is small, and a minimum rotation speed at the vehicle speed at that time or a value in the vicinity thereof is set. The minimum rotational speed at the vehicle speed is a value realized when the transmission ratio of the CVT 14 is set to the transmission ratio γmin on the highest gear side. As shown in FIG. 4, since the engine 10 stops when the rotational speed during deceleration of the vehicle falls below the idle rotational speed NE0, the basic target input rotation occurs when the vehicle speed V decreases and reaches the vehicle speed V2 (> V0). The speed is fixed at NE0 and guarded.
[0028]
In the next step 120, the transmission ECU 31 determines whether the accelerator pedal 34 is not depressed (OFF state), that is, whether the vehicle is decelerating based on the detection signal of the accelerator sensor 35. If the accelerator is not OFF, the process proceeds to step 140. In step 140, the transmission ECU 31 sets the target rotational speed increase amount to “0”, and then proceeds to step 150.
[0029]
On the other hand, if the accelerator is OFF in step 120, the vehicle is decelerating, and the process proceeds to step 130. In step 130, the transmission ECU 31 refers to the map shown in FIG. 3, calculates the target rotational speed increase amount UNE corresponding to the vehicle speed at that time, and then proceeds to step 150. This map is set based on the vehicle speed V during vehicle deceleration, and the target rotational speed increase amount UNE is predetermined according to a decrease in the vehicle speed V in the vehicle speed range from the vehicle speed V3 (> V2) to the vehicle speed V2. The vehicle speed V is set to increase to the rotational speed UNE1, and the vehicle speed V is fixed to the predetermined rotational speed UNE1 in the vehicle speed range from the vehicle speed V2 to the vehicle speed V1 (<V2). Further, the target rotational speed increase amount is set so that the vehicle speed V gradually decreases from the predetermined rotational speed UNE1 to 0 as the vehicle speed V decreases in the vehicle speed range from the vehicle speed V1 to the vehicle speed V0 (<V1).
[0030]
In step 150, the transmission ECU 31 adds the rotation speed increase amount calculated in step 130 or step 140 to the basic target input rotation speed calculated in step 110 to obtain the target input rotation speed. calculate. Therefore, when the vehicle is decelerating, the target input rotational speed TNE is obtained by adding the target rotational speed increase amount to the minimum rotational speed NE0 based on the vehicle speed V. That is, the target input rotational speed TNE is a constant value NE1 (NE0 + UNE1) in the vehicle speed range from the vehicle speed V3 to the vehicle speed V1. Further, when the vehicle speed V is in the vehicle speed range from the vehicle speed V1 to the vehicle speed V0, the target input rotational speed TNE gradually decreases from the constant value NE1 to NE0 as the vehicle speed V decreases.
[0031]
The reason for setting the up amount UNE to 0 as the vehicle speed V decreases in the vehicle speed range from the vehicle speed V1 to V0 is as follows. That is, when the vehicle speed V falls below V3 during vehicle deceleration, the target input rotational speed TNE is set to a constant value NE1 (NE0 + UNE1). This is because when the vehicle is decelerated, it is necessary to set the gear ratio γ of the CVT 14 to the gear ratio on the low gear side in order to obtain good acceleration performance at the next acceleration, that is, the gear shift response and drive response. This is to ensure the return performance of the transmission ratio γ of the CVT 14 to the transmission ratio γmax on the lowest gear side during sudden deceleration of the vehicle.
[0032]
However, if the lockup clutch mechanism 12 is engaged to a low vehicle speed while the target input rotational speed TNE is maintained at the constant value NE1, the deceleration acceleration increases with the change of the gear ratio to the low gear side. It will cause deterioration of the ability. Therefore, when the vehicle speed V falls below V1, the target input rotation speed TNE is set to gradually decrease to NE0 as the vehicle speed V decreases, and the transmission ratio of the CVT 14 is set to the low gear so as to be the target input rotation speed TNE. The transmission is controlled so that the transmission gear ratio becomes the same. When the gear ratio of the CVT 14 is controlled to the low gear side, the deceleration acceleration increases. However, since the target rotational speed increase amount at a speed lower than the vehicle speed V1 is reduced, the amount of change in the gear ratio of the CVT 14 to the low gear side is reduced. Therefore, the increase in deceleration acceleration can be mitigated and the deterioration of drivability can be suppressed.
[0033]
As described above, according to the transmission control device for a continuously variable transmission according to this embodiment, the following effects can be obtained.
In the present embodiment, when the vehicle is decelerated, the target input rotational speed TNE of the CVT 14 is increased from the minimum rotational speed at the vehicle speed at that time, and the gear ratio of the CVT 14 is set to the high rotational low gear side. The shift response and drive response of the CVT 14 can be improved, and the return performance of the transmission ratio of the CVT 14 to the lowest gear side during sudden deceleration can be improved. Further, in the vehicle speed range from the first vehicle speed V0 to the second vehicle speed V1 at which the lockup clutch mechanism 12 is released, the increase amount UNE of the target input rotational speed TNE is set to gradually decrease as the vehicle speed decreases. Therefore, the change in the gear ratio of the CVT 14 to the low gear side during sudden deceleration when the lockup clutch mechanism 12 is engaged can be suppressed, and the increase in deceleration acceleration can be mitigated. It is possible to suppress deterioration of drivability.
[0034]
In the present embodiment, during vehicle deceleration, the target input rotational speed TNE of the CVT 14 at the time of deceleration is set to the lowest vehicle speed at that time based on the fact that the vehicle speed has fallen below the third vehicle speed V3 that is higher than the second vehicle speed V1. Since the rotational speed is increased more than the third vehicle speed V3, the gear ratio of the CVT 14 is on the high gear side on the higher vehicle speed side, and driving with good fuel consumption can be performed.
[0035]
In the present embodiment, it is determined whether or not the vehicle is decelerating based on the accelerator pedal 34 being turned off. Therefore, it becomes possible to appropriately grasp the driver's intention and accurately determine whether or not the vehicle is in a deceleration state.
[0036]
In addition, the control apparatus of the vehicle with a clutch mechanism of this embodiment demonstrated above can also be changed as follows.
In the above embodiment, the target rotational speed increase amount UNE is set so that the target input rotational speed becomes a constant value in the vehicle speed range from the vehicle speed V3 to the vehicle speed V1, but the vehicle speed from the vehicle speed V3 as shown by the chain line in FIG. In the vehicle speed range up to V2 ′ (> V2), the increase amount is increased as the vehicle speed V decreases, and in the vehicle speed range from the vehicle speed V2 ′ to the vehicle speed V1, the increase amount is decreased as the vehicle speed V decreases. It may be. It should be noted that the degree of decrease in the up amount in the vehicle speed range from the vehicle speed V2 ′ to the vehicle speed V1 is preferably smaller than the degree of decrease in the up amount in the vehicle speed range from the vehicle speed V1 to the vehicle speed V0. In this way, the body sensitivity of the deceleration acceleration increases as the vehicle speed decreases, but the change in the deceleration acceleration near the lockup OFF vehicle speed can be reduced, and the deterioration of drivability is suitably suppressed. can do.
[0037]
In the above embodiment, a belt type is adopted as the CVT 14, but a toroidal CVT may be adopted.
In the above embodiment, the present invention is embodied in a vehicle in which the CVT 14 is disposed between the lockup clutch mechanism 12 and the drive wheel 17, that is, the CVT 14 is connected to the output shaft side of the lockup clutch mechanism 12. The present invention may be embodied in a vehicle having a configuration in which a lockup clutch mechanism is disposed between the CVT and the drive wheel, that is, a configuration in which the CVT 14 is connected to the input shaft side of the lockup clutch mechanism.
[0038]
-A vehicle equipped with a continuously variable transmission to which the control device of the above embodiment is applied employs a hydraulically operated friction clutch mechanism as a clutch mechanism, but the configuration of the clutch mechanism is arbitrary, and other electromagnetic clutches and the like The clutch mechanism may be employed. In short, as long as the vehicle employs a clutch mechanism that connects and disconnects the engine and the transmission, a control device similar to or equivalent to the above-described embodiments can be applied.
[0039]
Next, other technical ideas that can be grasped from the above embodiment will be described below.
3. The transmission control apparatus for a continuously variable transmission according to claim 2, wherein the setting means sets the target input rotational speed to a predetermined rotational speed in a vehicle speed range from the second vehicle speed to the third vehicle speed. A transmission control device for a continuously variable transmission, in which an increase amount of a target rotation speed is set to
[0040]
The shift control device for a continuously variable transmission according to claim 2, wherein the setting means has a maximum increase in the target input rotation speed in the middle of a vehicle speed range from the second vehicle speed to the third vehicle speed. A transmission control device for a continuously variable transmission that sets the amount of increase so that
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a continuously variable transmission-equipped vehicle and a control device thereof according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a procedure for setting the target input rotation speed in the embodiment.
FIG. 3 is an explanatory diagram showing an example of a map used for calculating a target rotational speed increase amount during vehicle deceleration.
FIG. 4 is an explanatory diagram showing an example of a control mode of a vehicle speed and a target input rotation speed during vehicle deceleration.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Engine, 14 ... Continuously variable transmission (CVT), 12 ... Lock-up clutch mechanism (clutch mechanism), 17 ... Drive wheel, 19 ... Hydraulic control circuit, 30 ... Engine ECU, 31 ... Transmission ECU (setting) Means, control means), 33 ... vehicle speed sensor, 35 ... accelerator sensor.

Claims (2)

Connected to the input side or output side of the clutch mechanism that is engaged when the vehicle decelerates and connects the power transmission path between the prime mover and the drive wheel, and continuously changes the input rotational speed on the prime mover side to drive wheel side In a transmission control device for a continuously variable transmission that outputs as an output rotational speed of
When the vehicle is decelerated, the target input rotational speed of the continuously variable transmission is increased from the minimum rotational speed at the vehicle speed at that time, and the vehicle speed during vehicle deceleration is the first vehicle speed at which the clutch mechanism is disengaged. To the second vehicle speed higher than the first vehicle speed, the target input rotation speed is set so that the increase amount of the target input rotation speed gradually decreases as the vehicle speed decreases. Setting means for setting;
A transmission control device for a continuously variable transmission, comprising: control means for controlling a gear ratio of the continuously variable transmission so that an input rotational speed of the continuously variable transmission becomes the target input rotational speed. The transmission control device for a continuously variable transmission according to claim 1,
The setting means sets the target input rotation speed of the continuously variable transmission mechanism to the minimum rotation speed at the vehicle speed at that time based on the fact that the vehicle speed falls below a third vehicle speed higher than the second vehicle speed during vehicle deceleration. A transmission control device for a continuously variable transmission that is more increased.

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