JP7410669B2 - Vehicle control device and vehicle control method - Google Patents

Description

The present invention relates to a vehicle control device and a vehicle control method.

Patent Document 1 discloses a technique for detecting a complete engagement point and an opening starting point of a lock-up clutch based on a rotation speed ratio that is a ratio between a turbine rotation speed and an engine rotation speed.

Japanese Patent Application Publication No. 5-180327

When releasing the engaged state of the lock-up clutch, for example, the lock-up clutch may be completely released (input/output plate non-contact) for the purpose of increasing the re-acceleration response from a coasting state where the accelerator pedal is off. Instead, it is conceivable to wait at a zero point where the input and output plates are in contact but the transmitted torque capacity is zero.

However, since the technology disclosed in Patent Document 1 considers only the turbine rotation speed and engine rotation speed, it is difficult to detect the oil pressure at which the lock-up clutch reaches the zero point (zero-point oil pressure). , the lock-up clutch cannot be held at zero point.

The present invention has been made in view of such technical problems, and an object of the present invention is to enable the lock-up clutch to wait at the zero point when releasing the engaged state of the lock-up clutch.

According to an aspect of the present invention, there is provided a control device for a vehicle having a torque converter, the rotational speed of an input element of the torque converter, the rotational speed of an output element of the torque converter, and the input element of the torque converter. and the torque input to the lock-up clutch at a timing when the torque capacity of the lock-up clutch of the torque converter can be considered to be equal to zero when the lock-up clutch of the torque converter is transitioned to the released state. A vehicle control device is provided, comprising a control unit that learns a command pressure of supplied hydraulic pressure.

According to another aspect of the present invention, a corresponding method for controlling a vehicle is provided.

According to these aspects, the estimated torque capacity of the lock-up clutch can be calculated by considering the torque input to the input element of the torque converter. Therefore, the oil pressure at the time when the estimated torque capacity becomes zero while the lock-up clutch is moving from engagement to disengagement can be learned as the zero-point oil pressure. It can be put on standby.

1 is a schematic configuration diagram of a vehicle to which a control device according to an embodiment of the present invention is applied. It is a flowchart which shows the content of learning processing. 3 is a time chart showing how learning processing is executed.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a vehicle 100. Vehicle 100 includes an engine 1, an automatic transmission 3 connected to the engine 1, an oil pump 5, drive wheels 6, and a controller 10 as a control device.

The engine 1 is an internal combustion engine that uses gasoline, light oil, or the like as fuel, and functions as a driving source for driving. The rotational speed, torque, etc. of the engine 1 are controlled based on commands from the controller 10.

The automatic transmission 3 includes a torque converter 2, a fastening element 31, a variator 30, a hydraulic control valve unit 40 (hereinafter also simply referred to as "valve unit 40"), and an oil pan 32 that stores hydraulic oil. , is provided.

Torque converter 2 is provided on a power transmission path between engine 1 and drive wheels 6. Torque converter 2 transmits power via fluid. Moreover, the torque converter 2 has a lock-up clutch 2a. When the lock-up clutch 2a is engaged, the input shaft 2b as an input element of the torque converter 2 and the output shaft 2c as an output element are directly connected, and the input shaft 2b and output shaft 2c rotate at the same speed.

The fastening element 31 is arranged on the power transmission path between the torque converter 2 and the variator 30. The fastening element 31 includes a forward clutch and a reverse brake (not shown). The fastening element 31 is controlled by hydraulic oil whose pressure is regulated by the valve unit 40 using the discharge pressure of the oil pump 5 as a source pressure based on a command from the controller 10 . As the fastening element 31, for example, a normally open wet type multi-disc clutch is used.

The variator 30 is disposed on the power transmission path between the fastening element 31 and the drive wheels 6, and changes the gear ratio steplessly according to the vehicle speed, the opening degree of the accelerator pedal, and the like. The variator 30 includes a primary pulley 30a, a secondary pulley 30b, and a belt 30c wound around both pulleys 30a and 30b. By moving the movable pulley of the primary pulley 30a and the movable pulley of the secondary pulley 30b in the axial direction by pulley pressure and changing the pulley contact radius of the belt 30c, the speed ratio is changed steplessly. The pulley pressure acting on the primary pulley 30a and the pulley pressure acting on the secondary pulley 30b are regulated by the valve unit 40 using the discharge pressure from the oil pump 5 as the source pressure. The variator 30 may be a toroidal continuously variable transmission mechanism or a stepped automatic transmission mechanism.

The differential 12 is connected to the output shaft of the secondary pulley 30b of the variator 30 via a final reduction gear mechanism (not shown). A drive wheel 6 is connected to the differential 12 via a drive shaft 13.

The oil pump 5 is driven by the rotation of the engine 1 being transmitted via a belt. The oil pump 5 is configured by, for example, a vane pump. The oil pump 5 sucks up hydraulic oil stored in the oil pan 32 and supplies the hydraulic oil to the valve unit 40. The hydraulic oil supplied to the valve unit 40 is used to drive each pulley 30a, 30b, drive the fastening element 31, and lubricate each element of the automatic transmission 3.

The controller 10 is composed of a microcomputer including a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input/output interface (I/O interface). The controller 10 can also be configured with a plurality of microcomputers. Specifically, the controller 10 can be configured by an ATCU that controls the automatic transmission 3, an SCU that controls the shift range, an ECU that controls the engine 1, and the like.

The controller 10 includes a first rotation speed sensor 51 that detects the rotation speed Ne of the engine 1 (= rotation speed of the input shaft 2 b of the torque converter 2 (pump rotation speed)), and a rotation speed of the output shaft 2 c of the torque converter 2 ( A second rotational speed sensor 52 detects the output rotational speed of the fastening element 31 (=rotational speed of the primary pulley 30a), and a third rotational speed sensor 53 detects the rotational speed of the secondary pulley 30b. A fourth rotational speed sensor 54, a vehicle speed sensor 55 that detects the vehicle speed, an inhibitor switch 56 that detects the select range of the variator 30 (the state of the select lever or select switch that switches between forward range, reverse range, neutral range, and parking range), and the accelerator. Signals are input from an accelerator opening sensor 57 that detects the pedal opening, a pedal force sensor 58 that detects the brake pedal force, and the like. The controller 10 controls various operations of the engine 1 and automatic transmission 3 based on these input signals.

By the way, when releasing the engaged state of the lock-up clutch 2a, for example, the lock-up clutch 2a is completely released (input/output plate non-contact) for the purpose of increasing the re-acceleration response from a coasting state where the accelerator pedal is off. ), it is conceivable to wait at a zero point where the input/output plates are in contact but the transmitted torque capacity is zero.

However, the oil pressure at which the lock-up clutch 2a reaches the zero point (zero-point oil pressure) varies from vehicle to vehicle, and also changes depending on the degree of wear of the lock-up clutch 2a. Therefore, it is difficult to preset the zero point oil pressure based on the specifications of the lockup clutch 2a.

Therefore, in the present embodiment, the control unit of the controller 10 calculates the estimated torque capacity TLU of the lockup clutch 2a, and executes a learning process to learn the zero point oil pressure of the lockup clutch 2a based on the calculation result. It has become. Note that the control unit in this embodiment is a virtual unit that has the function of executing the learning process of the controller 10.

The learning process executed by the controller 10 will be described below with reference to the flowchart shown in FIG. 2.

In step S11, the controller 10 determines whether the selected range is the forward range and the vehicle 100 is stopped.

When the controller 10 determines that the select range is the forward range and the vehicle 100 is stopped, the process proceeds to step S12. Further, when the controller 10 determines that the select range is the forward range and the vehicle 100 is not stopped, it repeatedly performs the process of step S11.

In step S12, the controller 10 determines whether the brake is ON.

When the controller 10 determines that the brake is ON, the process proceeds to step S13. Further, if the controller 10 determines that the brake is not ON, the process returns to step S11 and repeats the process.

In step S13, the controller 10 determines whether the rotational speed Ne of the engine 1 is stable.

When the controller 10 determines that the rotational speed Ne of the engine 1 is stable, the process proceeds to step S14. Further, if the controller 10 determines that the rotational speed Ne of the engine 1 is not stable, it repeatedly performs the process of step S13.

If the estimated torque capacity TLU is calculated in a state where the rotational speed Ne of the engine 1 is unstable and low, the calculation result of the estimated torque capacity TLU will also vary due to the influence of fluctuations in the rotational speed Ne. Therefore, the requirement for proceeding to step S14 is that the rotational speed Ne of the engine 1 is stable.

In step S14, the controller 10 increases the hydraulic pressure command (hereinafter referred to as LU command pressure) supplied to the lock-up clutch 2a to a first predetermined pressure.

The first predetermined pressure is an LU command pressure that moves the piston of the lockup clutch 2a to the engagement side within a range where the input/output plates of the lockup clutch 2a do not come into contact, and is determined in advance based on the specifications of the lockup clutch 2a, experimental results, etc. Set.

In step S15, the controller 10 gradually increases the LU command pressure.

In step S16, the controller 10 calculates the estimated torque capacity TLU of the lock-up clutch 2a, and determines whether the calculated estimated torque capacity TLU has exceeded a first predetermined value. The first predetermined value is slightly larger than "0" and is a value that allows the torque capacity of the lock-up clutch 2a to be considered to be equivalent to zero. For example, it is 5 [N·m].

The estimated torque capacity TLU is determined by the difference between the torque TENG of the engine 1 and τNe ² . τ is a capacity coefficient of the torque converter 2 determined from the specifications of the torque converter 2 and the rotational speed Nt of the output shaft 2c of the torque converter 2. Further, as the torque TENG of the engine 1, an engine torque signal can be used.

This is because TENG=τNe ² holds true when the lock-up clutch 2a is in the released state. That is, when the lock-up clutch 2a is in the released state, TLU=0, and in reality, TENG=τNe ² +TLU. Therefore, TLU=TENG-τNe ² .

In the process of transitioning the lockup clutch 2a from the released state to the engaged state, it is considered that the lockup clutch 2a reaches the zero point at the timing when the calculated estimated torque capacity TLU becomes equal to or greater than the first predetermined value. That is, the LU command pressure at the timing when the calculated estimated torque capacity TLU becomes equal to or higher than the first predetermined value is the LU command pressure for bringing the lockup clutch 2a to the zero point.

When the controller 10 determines that the calculated estimated torque capacity TLU has become equal to or greater than the first predetermined value, the controller 10 moves the process to step S17. Further, if the controller 10 determines that the calculated estimated torque capacity TLU is not equal to or greater than the first predetermined value, the controller 10 returns to step S15 and repeats the process.

In step S17, the controller 10 learns the LU command pressure at the timing when the calculated estimated torque capacity TLU exceeds the first predetermined value as the first zero point oil pressure.

In step S18, the controller 10 gradually increases the LU command pressure to a second predetermined pressure.

The second predetermined pressure is an LU command pressure that moves the piston of the lockup clutch 2a to a position where the lockup clutch 2a is in a slip state, and is set in advance based on the specifications of the lockup clutch 2a, experimental results, etc.

In step S19, the controller 10 waits for a predetermined time with the LU command pressure set to the second command pressure.

In step S20, the controller 10 gradually reduces the LU command pressure.

In step S21, the controller 10 calculates the estimated torque capacity TLU of the lock-up clutch 2a, and determines whether the calculated estimated torque capacity TLU has become equal to or less than a second predetermined value. Like the first predetermined value, the second predetermined value may be a value that is slightly larger than "0" and can be considered to be equivalent to the torque capacity of the lockup clutch 2a being zero. For example, it is 5 [N·m]. Further, the second predetermined value may be "0".

In the process of transitioning the lock-up clutch 2a from the slip state to the released state, it is considered that the lock-up clutch 2a reaches the zero point at the timing when the calculated estimated torque capacity TLU becomes equal to or less than the second predetermined value. That is, the LU instruction pressure at the timing when the calculated estimated torque capacity TLU becomes equal to or less than the second predetermined value is the LU instruction pressure for bringing the lockup clutch 2a to the zero point.

When the controller 10 determines that the calculated estimated torque capacity TLU has become equal to or less than the second predetermined value, the controller 10 moves the process to step S22. Further, if the controller 10 determines that the calculated estimated torque capacity TLU is not equal to or less than the second predetermined value, the controller 10 returns to step S20 and repeats the process.

In step S22, the controller 10 learns the LU command pressure at the timing when the calculated estimated torque capacity TLU becomes equal to or less than the second predetermined value as the second zero point oil pressure.

In step S23, the controller 10 lowers the LU command pressure to completely release the lock-up clutch 2a.

As described above, in the present embodiment, the controller 10 controls the rotation speed Ne of the engine 1 (=the rotation speed of the input shaft 2b of the torque converter 2), the rotation speed Nt of the output shaft 2c of the torque converter 2, and the rotation speed Nt of the output shaft 2c of the torque converter 2. The estimated torque capacity TLU is calculated based on the torque TENG of the engine 1, which is the torque input to the input shaft 2b of No. 2.

Then, the lock-up clutch 2a is transitioned from the released state to the engaged state, and the LU command pressure at the timing when the calculated estimated torque capacity TLU exceeds the first predetermined value is set to the zero point of the lock-up clutch 2a. Learn as the first zero point oil pressure for.

Additionally, the lock-up clutch 2a is transitioned from the slip state to the released state, and the LU command pressure at the timing when the calculated estimated torque capacity TLU becomes equal to or less than the second predetermined value is set to zero point of the lock-up clutch 2a. Learn as the second zero point oil pressure for.

The reason why the first zero point oil pressure and the second zero point oil pressure are learned respectively is that the lockup clutch 2a is changed from the released state to the engaged state due to the influence of hysteresis and response delay of the solenoid valve when operating the lockup clutch 2a. This is because the zero-point oil pressure when the lock-up clutch 2a is transitioned from the engaged state to the released state is different from the zero-point oil pressure when the lock-up clutch 2a is transitioned from the engaged state to the released state.

In other words, in this embodiment, by using the second zero-point oil pressure learned through the learning process, it is possible to make the lock-up clutch 2a wait at the zero point when releasing the engaged state of the lock-up clutch 2a. ing.

Further, in this embodiment, the first zero point oil pressure and the second zero point oil pressure are learned while the select range is the forward range and the vehicle 100 is stopped. This is because learning can be performed in a stable state when the vehicle 100 is stopped. Furthermore, learning opportunities can be increased by performing learning while the forward range is selected, that is, when the drive wheels 6 and torque converter 2 are in a power transmission state.

However, if the lock-up clutch 2a is completely engaged while the vehicle is stopped and the drive wheels 6 and the torque converter 2 are in a power transmission state, the engine 1 will stall. Therefore, by setting the second predetermined pressure, the lock-up clutch 2a is prohibited from being fully engaged during the execution of the learning process, and the second zero-point oil pressure is learned by transitioning from the slip state to the release state.

Note that, in step S19, the controller 10 waits for a predetermined time with the LU command pressure set to the second command pressure. This is a waiting time until the state of vehicle 100 becomes stable. However, the process of step S19 may be omitted.

Next, the manner in which the learning process is executed will be described with reference to the time chart shown in FIG. 3.

When the selection range is changed from the neutral range to the forward range at time t1, the forward clutch of the engagement element 31 is engaged, and the drive wheels 6 and the torque converter 2 enter a power transmission state. As a result, the rotational speed Nt of the output shaft 2c of the torque converter 2 decreases. Furthermore, the rotational speed Ne of the engine 1 is temporarily reduced due to the load on the torque converter 2.

When it is determined that the rotational speed Ne of the engine 1 has become stable at time t2, the LU command pressure becomes the first predetermined pressure.

After that, the LU command pressure gradually increases, and the actual pressure of the hydraulic pressure supplied to the lockup clutch 2a (hereinafter referred to as LU actual pressure) also increases.

At time t3, the estimated torque capacity TLU becomes equal to or greater than the first predetermined value. The controller 10 learns the LU command pressure at this timing as the first zero point oil pressure.

Thereafter, the LU command pressure gradually increases and reaches the second predetermined pressure at time t4.

When the standby time has elapsed (time t5), the LU command pressure gradually decreases, and the LU actual pressure also decreases.

At time t6, the estimated torque capacity TLU becomes equal to or less than the second predetermined value. The controller 10 learns the LU command pressure at this timing as the second zero point oil pressure.

At time t7, the LU command pressure decreases and the lock-up clutch 2a is completely released.

As described above, the first zero point oil pressure and the second zero point oil pressure are different due to the influence of hysteresis, response delay, etc. of the solenoid valve when operating the lockup clutch 2a. Specifically, as shown in FIG. 3, the second zero point oil pressure is lower than the first zero point oil pressure. Therefore, if the first zero-point oil pressure is used as the zero-point oil pressure when releasing the lock-up clutch 2a, the lock-up clutch 2a will have an excessive torque capacity, and the zero point cannot be reached (at time t6'). reference).

As described above, in the present embodiment, the controller 10 inputs the rotational speed Ne of the input shaft 2b of the torque converter 2, the rotational speed Nt of the output shaft 2c of the torque converter 2, and the input shaft 2b of the torque converter 2. The second zero-point oil pressure at which the lock-up clutch 2a of the torque converter 2 is shifted to the released state is learned based on the torque TENG.

According to this, by considering the torque TENG input to the input shaft 2b of the torque converter 2, the estimated torque capacity TLU of the lock-up clutch 2a can be calculated. Therefore, the oil pressure at the timing when the estimated torque capacity TLU becomes zero while the lock-up clutch 2a is moving from engagement to disengagement can be learned as the second zero-point oil pressure. The clutch 2a can be kept on standby at the zero point. (Effects corresponding to claims 1 and 3)

Further, the controller 10 causes the lock-up clutch 2a to transition from the slip state to the released state when the drive wheels 6 are stopped and the drive wheels 6 and the torque converter 2 are in a power transmission state. By doing so, the second zero point oil pressure will be learned.

According to this, since the vehicle 100 is stopped, learning can be performed in a stable state. Furthermore, learning opportunities can be increased by performing learning while the drive wheels 6 and torque converter 2 are in a power transmission state (for example, the forward range is selected). Furthermore, since the second zero point oil pressure is learned by transitioning from the slip state to the release state without completely engaging the lock-up clutch 2a, the drive wheels 6 and the torque converter 2 are in the power transmission state and the vehicle Even if learning of the second zero point oil pressure is performed while the engine 100 is stopped, stalling of the engine 1 can be prevented. (Effect corresponding to claim 2)

Although the embodiments of the present invention have been described above, the above embodiments are merely examples of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiments. isn't it.

100 Vehicle 2 Torque converter 2a Lock-up clutch 2b Input shaft 2c Output shaft 6 Drive wheel 10 Controller (control device, control unit)

Claims (3)

A control device for a vehicle having a torque converter,
A lock-up clutch of the torque converter is set to a released state based on a rotational speed of an input element of the torque converter, a rotational speed of an output element of the torque converter, and a torque input to the input element of the torque converter. a control unit that learns the command pressure of the hydraulic pressure supplied to the lockup clutch at a timing when the torque capacity of the lockup clutch at the time of transition can be considered to be equivalent to zero ;
A vehicle control device characterized by: The vehicle control device according to claim 1,
The control unit transitions the lock-up clutch from the slip state to the released state when the drive wheels are stopped and the drive wheels and the torque converter are in a power transmission state. performing said learning by;
A vehicle control device characterized by: A method for controlling a vehicle having a torque converter, the method comprising:
A lock-up clutch of the torque converter is set to a released state based on a rotational speed of an input element of the torque converter, a rotational speed of an output element of the torque converter, and a torque input to the input element of the torque converter. Learning the command pressure of the hydraulic pressure supplied to the lock-up clutch at a timing when the torque capacity of the lock-up clutch at the time of transition can be considered to be equivalent to zero ;
A vehicle control method characterized by:

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