JP5669594B2 - Vehicle control apparatus equipped with continuously variable transmission - Google Patents

Description

The present invention provides a vehicle control device including a belt-type continuously variable transmission, particularly a normal driving mode (for example, D range), and a high-speed rotation mode (for example, S, B) having a higher target input rotational speed than the normal driving mode. The present invention relates to a vehicle control device equipped with a continuously variable transmission having a range and the like.

2. Description of the Related Art Conventionally, a vehicle in which engine driving force is transmitted to an input shaft of a belt type continuously variable transmission via a torque converter having a lockup clutch and an output shaft of the continuously variable transmission is connected to an axle is known. In the continuously variable transmission, a target input rotation speed is set based on at least the accelerator opening and the vehicle speed, and shift control is performed so as to approach the target input rotation speed. Such a continuously variable transmission includes a normal driving mode such as the D range and a high speed rotation mode such as the S and B ranges in which the target input rotation speed is set higher than the normal driving mode. There is one that can be switched between a normal traveling mode and a high-speed rotation mode by manual operation. The S range is a traveling mode that is used when traveling on an uphill or downhill, for example, and activates an engine brake. The B range is a traveling mode that is used when traveling on a steep uphill or downhill, for example, and when strong engine braking is required.

4A is a shift diagram of the continuously variable transmission, and FIG. 4B is a lock-up OFF diagram corresponding thereto. As is well known, the shift diagram is a diagram in which the target input rotational speed is set based on the accelerator opening and the vehicle speed, and the accelerator opening between Low (maximum transmission ratio) and High (minimum transmission ratio). A plurality of input rotational speeds (turbine rotational speeds) are set in accordance with. FIG. 4A shows three input rotation speed characteristics in the normal travel mode when the accelerator opening is 100%, 50%, and 0%. Compared to the minimum target input speed (characteristic when the accelerator opening is 0%) in the normal travel mode (D), the minimum target input speed (the accelerator opening is 0%) in the high speed rotation mode (S, B). Characteristic) is set high.

On the other hand, the lock-up OFF diagram is a diagram in which the vehicle speed / accelerator opening is set when the lock-up clutch provided in the torque converter is switched from ON to OFF. As shown in the shift diagram, since the minimum target input rotational speed is different between the normal driving mode (D) and the high speed rotation mode (S, B), the lockup OFF vehicle speed in the high speed rotation mode (S, B) is normal driving. The vehicle speed is set higher than the lockup OFF vehicle speed in the mode (D). The reason for this is that in the case of a continuously variable transmission, the feeling of deceleration increases when coasting down (deceleration with the accelerator off), so in the high speed rotation mode, the lockup clutch is turned off on the higher vehicle speed side than in the normal travel mode. This is to prevent the feeling of deceleration from becoming excessive.

By the way, the driver may switch from the normal travel mode to the high-speed rotation mode (for example, D → S, B) during deceleration in the accelerator opening fully closed state. When the switching is performed in a region (for example, indicated by V _DS ) that is higher than the lockup OFF vehicle speed in the normal travel mode (D) and lower than the lockup OFF vehicle speed in the high speed rotation mode (S, B), Shift control (rotation speed increase, deceleration increase) and lock-up OFF are started simultaneously. However, due to a delay in the operation of the lock-up clutch, the lock-up may be turned off at a large deceleration and a shock may occur.

FIG. 5 is a time chart showing such a situation. At time t1, the accelerator is fully closed and deceleration is started. The vehicle speed is higher than the lockup OFF speed of the normal running mode, switching the shift lever to D → S at time t2, which is lower vehicle speed V _DS than the lock-up OFF vehicle speed of the high speed rotation mode, the lock-up OFF signal is output, Shift control of the continuously variable transmission and lock-up OFF are started simultaneously. In order to turn off lockup, it is necessary to supply hydraulic oil to the release side oil chamber, but since the engine speed is low, the supply of hydraulic oil is delayed and lockup OFF is delayed. . On the other hand, the continuously variable transmission increases the input rotation speed from the target input rotation speed in the D range toward the target input rotation speed in the S range (shifts to the Low side), so that the deceleration rapidly increases due to the action of the engine brake. Increase. Eventually, when the lockup is actually turned off at time t3, the engine brake is released at that moment, so that a shock occurs.

In Patent Document 1, in an automatic transmission (including a continuously variable transmission) in which a lockup control pressure and a shift control pressure share a hydraulic pressure source, the shift control is prohibited together with the lockup release control during sudden braking. What prevents an engine stall is disclosed. Further, in Patent Document 2, in a vehicle including a torque converter having a lock-up clutch and a continuously variable transmission, a period from when one of lock-up connection and shift start is executed until a predetermined time elapses. The other prohibits execution.

Patent Document 1 is intended for control when the control timings of the lockup release control and the shift control overlap. However, the purpose is to prevent engine stall at the time of sudden braking, and the shift lever is set to D → S without operating the brake. The lock-up release shock when switching to can not be prevented. Patent Document 2 avoids duplication of lockup connection and shift start timing, and does not prevent a lockup release shock when the shift lever is switched from D to S.

JP-A-8-86353 Japanese Patent Laid-Open No. 8-17855

It is an object of the present invention to prevent or suppress the occurrence of shock when switching from the normal travel mode to the high speed rotation mode in a region higher than the lockup OFF vehicle speed in the normal travel mode and lower than the lockup OFF vehicle speed in the high speed rotation mode. It is to provide a control device.

In order to achieve the above object, the present invention provides a vehicle in which engine driving force is transmitted to a belt-type continuously variable transmission via a torque converter having a lock-up clutch. A target input rotational speed of the step transmission is set, and the continuously variable transmission has a normal traveling mode and a high-speed rotational mode in which the target input rotational speed is set higher than that of the normal traveling mode. In a vehicle that is switchable between a high-speed rotation mode and a high-speed rotation mode, the vehicle speed for releasing the lock-up clutch in the high-speed rotation mode is higher than the vehicle speed for releasing the lock-up clutch in the normal travel mode. is set, while decelerating the accelerator opening as a fully closed, the lock-up clutch in the normal running mode The lock-up clutch is released when the normal driving mode is switched to the high-speed rotation mode during traveling in a region where the vehicle speed is higher than the vehicle speed for releasing the vehicle and less than the vehicle speed for releasing the lock-up clutch in the high-speed rotation mode. There is provided a control device for a vehicle, characterized by comprising control means for starting shift control of the continuously variable transmission after detecting the above.

When the shift lever is switched from the normal travel mode to the high-speed rotation mode while traveling in the region above the lock-up OFF vehicle speed (vehicle speed for releasing the lock-up clutch) in the normal travel mode and below the lock-up OFF vehicle speed in the high speed rotation mode When the deceleration is large due to the shift control of the continuously variable transmission (shift to the Low side), the lockup may be turned off and a shock may occur. Therefore, in the present invention, after detecting that the lock-up clutch is actually turned off, control is performed so that the shift control of the continuously variable transmission is started. That is, the shift control of the continuously variable transmission is not started until the lockup OFF is detected. As a lockup OFF detection method, for example, depending on whether or not the differential rotation between the input rotation speed (engine rotation speed) of the lockup clutch and the output rotation speed (input rotation speed of the continuously variable transmission) has become a predetermined value or more. It can be detected. As described above, since the shift control of the continuously variable transmission is started after detecting the lock-up OFF, the increase in the deceleration due to the engine brake can be suppressed by the buffering action of the torque converter, and the lock-up OFF shock does not occur.

Contrary to the present invention, when the shift lever is switched from the high-speed rotation mode to the normal travel mode while traveling in the region that is higher than the lock-up OFF vehicle speed in the normal travel mode and lower than the lock-up OFF vehicle speed in the high-speed rotation mode. The continuously variable transmission is shifted to the High side and the lockup is turned on. In that case, there is no deceleration shock for shifting to the High side, and if the lock-up clutch engagement control is gently performed, the shock is reduced and does not cause a problem.

As described above, according to the present invention, the shift lever is switched from the normal travel mode to the high speed rotation mode while traveling in the region that is higher than the lockup OFF vehicle speed in the normal travel mode and lower than the lockup OFF vehicle speed in the high speed rotation mode. In this case, since the shift control of the continuously variable transmission is started after releasing the lockup, an increase in deceleration due to the engine brake can be suppressed, and a shock at the time of mode switching can be prevented or suppressed.

1 is a skeleton diagram showing a schematic configuration of a vehicle according to the present invention. It is a time chart figure of the lockup OFF signal in the present invention at the time of shifting from D range to S range during coast down, the number of rotations, and acceleration. It is a flowchart figure of the lockup clutch control and shift control which concern on this invention. It is a lockup diagram and a shift diagram. It is a time chart figure of the conventional lock-up OFF signal, rotation speed, and acceleration at the time of shifting from D range to S range during coast down.

FIG. 1 shows an example of the configuration of a vehicle equipped with a continuously variable transmission according to the present invention. An output shaft 1a of the engine 1 is connected to a continuously variable transmission 2 via a torque converter 3 having a lock-up clutch 3a, and the continuously variable transmission 2 is connected to a drive shaft 32 that drives wheels. The continuously variable transmission 2 is provided with a belt type continuously variable transmission 4, a hydraulic control device 7, an oil pump 6 driven by the engine 1, and the like.

The continuously variable transmission 2 includes a forward / reverse switching device 8, a primary pulley 11, a secondary pulley 21, and a V that is wound between the pulleys and transmits the rotation to the primary shaft 10 by switching the rotation of the turbine shaft 5 of the torque converter 3 between forward and reverse. The transmission 4 includes a belt 15, a differential device 30 that transmits the power of the secondary shaft 20 to the drive shaft 32, and the like. The V belt 15 may be a known metal belt composed of a continuous tension band and a large number of blocks supported by the tension band, or other belts such as a chain belt may be used.

The forward / reverse switching device 8 includes a planetary gear mechanism 80, a reverse brake B1, and a direct coupling clutch C1. The reverse brake B1 and the direct coupling clutch C1 are wet multi-plate brakes and clutches, respectively. A sun gear 81 of the planetary gear mechanism 80 is connected to the turbine shaft 5 as an input member, and a ring gear 82 is connected to the primary shaft 10 as an output member. The planetary gear mechanism 80 is a single pinion system, the reverse brake B1 is provided between the carrier 84 supporting the pinion gear 83 and the transmission case, and the direct coupling clutch C1 is provided between the carrier 84 and the sun gear 81. When the direct clutch C1 is released and the reverse brake B1 is engaged, the rotation of the turbine shaft 5 is reversed, decelerated and transmitted to the primary shaft 10, and the drive shaft 32 passes through the secondary shaft 20 in the same direction as the engine rotation direction. Since it rotates, it will be in a forward running state. Conversely, when the reverse brake B1 is released and the direct clutch C1 is engaged, the carrier 84 and the sun gear 81 rotate together, so that the turbine shaft 5 and the primary shaft 10 are directly connected, and the drive shaft 32 passes through the secondary shaft 20. Rotates in the direction opposite to the engine rotation direction, so that the vehicle travels backward.

The primary pulley 11 of the transmission 4 includes a fixed sheave 11a fixed to the primary shaft 10 and a movable sheave 11b supported on the primary shaft 10 so as to be axially movable and integrally rotatable. A cylinder 12 fixed to the primary shaft 10 is provided behind the movable sheave 11 b, and a primary oil chamber 13 is formed between the movable sheave 11 b and the cylinder 12. Shift control is performed by controlling the flow rate of the hydraulic oil supplied to the primary oil chamber 13.

The secondary pulley 21 includes a fixed sheave 21a fixed to the secondary shaft 20, and a movable sheave 21b supported on the secondary shaft 20 so as to be axially movable and integrally rotatable. A piston 22 fixed to the secondary shaft 20 is provided behind the movable sheave 21 b, and a secondary oil chamber 23 is formed between the movable sheave 21 b and the piston 22. By controlling the hydraulic pressure (secondary pressure) supplied to the secondary oil chamber 23, a belt clamping pressure necessary for torque transmission is applied. The secondary oil chamber 23 is provided with a bias spring 24 that applies an initial clamping pressure.

One end portion of the secondary shaft 20 extends toward the engine side, and the output gear 27 is fixed to this end portion. The output gear 27 meshes with the ring gear 31 of the differential device 30, and power is transmitted from the differential device 30 to the drive shaft 32 extending left and right to drive the wheels.

The continuously variable transmission 2 is controlled by the electronic control unit 100. The electronic control unit 100 includes an engine speed sensor 101, a secondary pulley speed sensor (vehicle speed sensor) 102, an accelerator opening (or throttle opening) sensor 103, a shift position sensor 104 that detects the position of the shift lever 108, a primary Detection signals are input from the pulley rotation speed sensor 105, the brake signal sensor 106, the hydraulic oil temperature sensor 107 of the CVT, and the like. Sensors other than the above sensors may be added. The electronic control unit 100 can detect the gear ratio based on the detection signals of the primary pulley rotation speed sensor 105 and the secondary pulley rotation speed sensor 102, and the detection signal comparison (difference) between the engine rotation speed sensor 101 and the primary pulley rotation speed sensor 105. Rotation) can detect the engaged / released state of the lockup clutch 3a. Since the reduction ratio by the forward / reverse switching device 8 acts between the output rotational speed (turbine rotational speed) of the lockup clutch 3a and the primary pulley rotational speed, it is needless to say that the differential rotational speed is obtained in consideration thereof. It is.

The shift lever 108 can be manually switched to, for example, each range position of P (parking), R (reverse), N (neutral), D (drive), S (sports), and B (brake). The S range is a traveling mode that is used when traveling on an uphill or downhill, for example, and activates an engine brake. The B range is a traveling mode in which a strong engine brake is operated, for example, when traveling on a steep uphill or a steep downhill. The S and B ranges are examples of the high-speed rotation mode in which the target input rotation speed is set higher than that of the D range. However, the S and B ranges are not limited to the S and B ranges. Any mode can be used.

The electronic control device 100 controls a plurality of solenoid valves built in the hydraulic control device 7. The hydraulic control device 7 is connected to the oil pump 6, the primary oil chamber 13, the secondary oil chamber 23, the reverse brake B1, and the direct coupling clutch C1 through a pipe. The electronic control device 100 determines a target primary rotational speed (target input rotational speed) according to a shift diagram (see FIG. 4A) set in advance according to the vehicle speed and the accelerator opening, and the hydraulic control device 7 By controlling the solenoid valve inside, the amount of oil supplied to the primary oil chamber 13 is adjusted, the primary rotational speed is controlled to be shifted to the target value, and another solenoid valve is controlled, so that the secondary oil chamber 23 is controlled. The oil pressure is controlled to a value that does not cause belt slip. Further, the hydraulic control device 7 has a function of controlling engagement / release of the lockup clutch 3a according to a lockup diagram (see FIG. 4B) set according to the vehicle speed and the accelerator opening. The hydraulic control device 7 also has a function of controlling the hydraulic pressure supplied to the reverse brake B1 and the direct coupling clutch C1.

Next, a vehicle control method according to the present invention will be described with reference to the time chart of FIG. FIG. 2 shows temporal changes in the lockup OFF signal, the rotation speed, and the vehicle acceleration when the shift lever is changed from D to S while decelerating with the accelerator opening being fully closed (coast down). At time t1, the accelerator is fully closed and deceleration is started. The vehicle speed is higher than the lockup OFF speed of D range, the shift lever at time t2 became lockup OFF vehicle speed lower than the vehicle speed V _DS of S-range switch to D → S, real lockup OFF signal is generated. Conventionally, the shift control of the continuously variable transmission and the lockup OFF are simultaneously started. However, in the present invention, the shift control of the continuously variable transmission is not started until the lockup clutch 3a is actually released. . In order to determine whether or not the lock-up clutch 3a has been released, for example, the input / output rotation speed difference (differential rotation) of the lock-up clutch 3a can be detected, and it can be determined whether or not the differential rotation has exceeded a predetermined value No. . The predetermined value No is determined based on the minimum differential rotation between the input member (pump impeller) and the output member (turbine runner) in the unlocked state of the lock-up clutch in anticipation of a predetermined detection error. When the differential rotation exceeds the predetermined value No at time t4, it is determined that the lockup is OFF, and the shift control is started at time t5 that is delayed from time t4. That is, the continuously variable transmission increases the rotational speed (shifts to the Low side) from the lowest target input rotational speed of the D range toward the lowest target input rotational speed of the S range, and the deceleration due to engine braking increases. However, since the lock-up clutch 3a is released before that, the vehicle does not feel a sudden deceleration due to the buffering action of the torque converter 3, and no lifting shock occurs.

FIG. 3 is a flowchart showing an example of the control method according to the present invention. First, it is determined whether or not the shift lever has been shifted from the D range to the S (B) range (step S1). When D → S (B) shift is performed, the current vehicle speed is compared with the D range lockup OFF vehicle speed (step S2). If the vehicle speed is lower than the D range lockup OFF vehicle speed, the lockup OFF is performed. At the same time, shift control of the continuously variable transmission is started (step S3). In this case, since the vehicle speed is sufficiently low, even if the lock-up OFF is delayed from the shift control, priority is given to returning to the Low state before the vehicle stops, and the shock can be almost ignored. If the vehicle speed is equal to or higher than the D range lockup OFF vehicle speed, the vehicle speed is subsequently compared with the S (B) range lockup OFF vehicle speed (step S4). When the vehicle speed is higher than the lockup OFF vehicle speed in the S (B) range, it is not necessary to release the lockup clutch, so the shift control of the continuously variable transmission is started (step 7). When the vehicle speed is equal to or lower than the lockup OFF vehicle speed in the S (B) range, first, a lockup OFF command is output (step S5), and the differential rotation of the lockup clutch is compared with a predetermined value No (step S6). When the differential rotation is less than or equal to the predetermined value No, the lockup OFF command is repeated. When the differential rotation becomes greater than the predetermined value No, it is determined that the lockup clutch has actually been released, and shift control of the continuously variable transmission is started (step 7).

In the above embodiment, the release of the lockup clutch 3a is determined based on whether or not the differential rotation exceeds a predetermined value No. However, the release may be detected based on the input / output rotational speed ratio of the lockup clutch 3a. Furthermore, since it can be considered that the lockup clutch is released if a predetermined time has elapsed from the output of the lockup OFF signal, the shift control may be started after a predetermined time from the generation of the lockup OFF signal.

DESCRIPTION OF SYMBOLS 1 Engine 2 Continuously variable transmission 3 Torque converter 3a Lock-up clutch 7 Hydraulic control device 11 Primary pulley 13 Primary oil chamber 21 Secondary pulley 23 Secondary oil chamber 100 Electronic control device 104 Shift position sensor 108 Shift lever

Claims (1)

A vehicle in which engine driving force is transmitted to a belt-type continuously variable transmission via a torque converter having a lock-up clutch,
The target input rotational speed of the continuously variable transmission is set by at least the accelerator opening and the vehicle speed,
The continuously variable transmission includes a normal driving mode and a high-speed rotation mode in which a target input rotation speed is set higher than the normal driving mode, and can be switched between the normal driving mode and the high-speed rotation mode by manual operation. In the vehicle
The vehicle speed for releasing the lock-up clutch in the high-speed rotation mode is set on the higher vehicle speed side than the vehicle speed for releasing the lock-up clutch in the normal travel mode,
While the vehicle is traveling in a region that is higher than the vehicle speed at which the lockup clutch is released in the normal driving mode and lower than the vehicle speed at which the lockup clutch is released in the high speed rotation mode while decelerating with the accelerator opening fully closed, Control of a vehicle, characterized by comprising control means for starting shift control of the continuously variable transmission after detecting the release of the lockup clutch when the travel mode is switched to the high speed rotation mode. apparatus.

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