JP3422187B2 - Control device for lock-up clutch - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling a lockup clutch arranged in parallel with a hydraulic power transmission device such as a torque converter, and more particularly to slip control for maintaining the lockup clutch in a slipping state. The present invention relates to a control device to perform.

[0002]

2. Description of the Related Art As is well known, in a fluid transmission device such as a torque converter, relative rotation between an input element and an output element inevitably occurs, which causes deterioration of fuel consumption in a vehicle.
Therefore, recently, a lock-up clutch is provided in parallel with the fluid transmission, that is, so as to directly connect the input element and the output element, and the lock-up clutch is selectively engaged to replace the fluid transmission. It has been attempted to improve fuel efficiency by transmitting torque.

Since the lockup clutch mechanically directly connects the prime mover such as the engine and the transmission, the change in the output torque of the prime mover is transmitted to the transmission as it is, resulting in a shock or a fog. It may worsen the sound. Therefore, when these ride comforts are taken into consideration, the area in which the lockup clutch can be engaged is limited. Also, if the lockup clutch is engaged or released, so-called slippage in the fluid transmission is eliminated, or slippage occurs, and the output shaft torque of the vehicle changes. If this occurs extremely, it is felt as an engagement shock, and Makes the ride worse.

Therefore, conventionally, in addition to controlling the lock-up clutch to simply engage and disengage, the transmission torque capacity is set to be slightly smaller than the input torque, and the slip state (semi-engagement state) is set. Control technology was developed,
One example thereof is described in JP-A-6-174074. The invention described in this publication is to perform slip control of the lock-up clutch in order to make the degree of engine braking, that is, the feeling of braking, constant on downhill roads and flat roads. The slip-control of the lock-up clutch is performed when driving downhill roads at certain times to ensure a certain amount of torque transmission between the engine and the wheels to generate engine braking force on downhill in accordance with the gradient. is there.

[0005]

In the slip control of the lock-up clutch at the time of descending the slope, in order to secure the engine braking force, the engine speed is maintained at a certain speed or more to perform the fuel cut. Therefore, in the conventional device, the slip control is performed when a large driving force such as the economy mode is not required. In other words, the slip control of the lockup clutch is prohibited when a large driving force such as a power mode is required. This is because when the driving force is required, the torque amplifying action of the torque converter is effectively used to obtain sufficient accelerating property at the time of reacceleration from the fully closed state of the throttle valve.

Therefore, in the above-mentioned conventional apparatus, when traveling downhill in the so-called power mode, even if the engine is braked by closing the throttle valve, a sufficient engine braking force cannot be obtained due to slippage in the torque converter. That is, since the acceleration due to gravity acts on the vehicle body on a downhill road, it is possible that the engine braking force is insufficient with the same engine braking force as when traveling on a flat road, which may cause a feeling of strangeness. Particularly when traveling in a so-called power mode, a large acceleration force and braking force are required, so if the engine braking force is felt to be insufficient on a downhill, the discomfort becomes more pronounced.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a lockup clutch control device in which the difference in deceleration feeling between a flat road and a downhill road is small.

[0008]

In order to achieve the above-mentioned object, the invention described in claim 1 is a lockup arranged in parallel with a fluid transmission for inputting power to a transmission. A slip-up control device for a lock-up clutch, which prohibits slip control of the clutch when the driver's driving direction is an output direction for traveling with an increased driving force, and permits it when the driving direction is a non-output direction In the above, the downhill control determining means for determining that the control for applying the engine braking is performed as the vehicle travels on the downhill road, the driving orientation determining means for determining the driving orientation, and the downhill control. When it is determined that the control for applying the engine braking is performed while traveling on a downhill road, and the driving direction determining means determines that the driving direction of the driver is the output direction, the lock And it is characterized in that it comprises a downhill during slip control permitting means for permitting the slip control of up clutch.

Therefore, according to the first aspect of the invention, when the driver's driving direction is an output direction requiring a large driving force, the lock-up clutch is normally maintained in the released state, and the power performance suitable for the driving direction is obtained. Also, the slip control of the lockup clutch is permitted when traveling on a downhill road, and torque is transmitted via the lockup clutch.Therefore, if the engine is braking downhill, the engine braking force will be lower than normal. Increase. As a result, at the time of downhill control in the output direction, a braking force that opposes the gravitational acceleration is obtained, and the feeling of deceleration approximates that when traveling on a flat road, and the discomfort due to the difference in deceleration can be eliminated.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, when the driving direction determining means determines that the driving direction of the driver is the output direction, the vehicle is traveling downhill. It is characterized by further comprising means for facilitating execution of control for applying the engine brake.

Therefore, according to the second aspect of the present invention, when it is determined that the driver is in the output-oriented direction, the downhill control is not performed in the non-output-oriented direction even if the vehicle is in the traveling state. The slope control will be executed, and the engine braking will be more effective.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail with reference to the drawings. First, a brief description will be given of an overall control system of a vehicle to which the present invention is applied. The automatic transmission 1 shown in FIG. 2 is similar to a conventionally known automatic transmission in that a friction engagement device such as a clutch or a brake is used. By engaging and disengaging the coupling device with hydraulic pressure, the transmission path of torque in the gear transmission mechanism mainly composed of multiple sets of planetary gear mechanisms is changed,
It is configured to set a predetermined shift speed. A torque converter 3 incorporating a lockup clutch 2 is provided as a device for inputting power to the gear shift mechanism.

The same torque converter 3 as the conventional one can be used, a pump impeller 5 is integrated with a front cover 4 connected to an engine (not shown), and a turbine runner 7 with a stator 6 sandwiched between the pump impeller 5 and the turbine runner 7. It is arranged facing each other. The turbine runner 7 is connected to an input shaft (not shown) in the gear shift mechanism. Further, a lockup clutch 2 is arranged so as to be engageable and disengageable so as to face the inner surface of the front cover 4, and the lockup clutch 2 is connected to an input shaft together with a turbine runner 7. Therefore, the lockup clutch 2 is arranged in parallel with respect to the fluid transmission device including the pump impeller 5, the stator 6 and the turbine runner 7.

A hydraulic control device 8 for controlling engagement / disengagement of the friction engagement device (that is, shift control) and engagement / disengagement of the lockup clutch 2 and slip control.
Is provided. The hydraulic control device 8 basically outputs a signal pressure by performing ON / OFF control of a solenoid valve or duty control to perform shift control, control of the lockup clutch 2 and hydraulic pressure regulation. It is like this. The structure is the same as that conventionally known.

The hydraulic control unit 8 is electrically controlled by an electronic control unit 9. The electronic control unit 9 is mainly composed of a so-called microcomputer including a central processing unit (CPU), a storage unit (RAM, ROM), and an input / output interface, and stores programs and data stored in advance and inputs. Perform various calculations based on the data
A control signal is output based on the calculation result. The electronic control unit 9 uses the detected data as the throttle opening θ, the engine speed Ne,
Turbine speed NT which is the input speed of the automatic transmission 1,
Vehicle speed V, shift position indicating a range selected by a shift device (not shown), signal from overdrive (O / D) switch, signal from brake switch, accelerator indicating depression amount of accelerator pedal (not shown) Opening,
The oil temperature, the signal from the shift mode switch, etc. are input.

Then, the electronic control unit 9 judges the shift stage based on these input data and the shift map stored in advance, and outputs a control signal for setting the shift stage, and the input data and The engagement / release of the lockup clutch 2 is controlled based on the map. FIG. 3 shows an example of a map defining the shift speed region, the lockup region of the lockup clutch 2 and the slip region. See also this figure
The symbol S-4 indicates the range of vehicle speed (output shaft speed) at which the lock-up clutch 2 is slip-controlled during deceleration at the fourth speed where the throttle opening is zero, and the symbol S-3 indicates the throttle opening. The range of the vehicle speed (output shaft rotation speed) in which the lockup clutch 2 is slip-controlled during the deceleration traveling at the third speed with the degree of zero is shown. That is, the automatic transmission 1 according to the present invention maintains the engine rotational speed at or above the fuel cut lower limit rotational speed (fuel cut return rotational speed) by controlling the slip-up of the lockup clutch 2 during deceleration, and extends the fuel cut time. It is configured to improve fuel efficiency.

Further, the electronic control unit 9 is equipped with a neural network, and judges on the basis of the input data whether the driving orientation is output orientation (acceleration orientation or sports orientation) requiring a large power or non-output orientation, Output a predetermined output signal. This neural network is a control system configured by using a computer program as software or hardware that is a combination of electronic elements as a model of a nerve cell group of a living body, and a conventionally known system can be adopted. Note that the driving orientation can be determined by a simpler means.

Further, the electronic control unit 9 is equipped with a system for performing downhill control. This downhill control is a control that downshifts to a gear position where engine braking is effective when traveling on a downhill road, and calculates the down slope of the road surface from the input data to obtain the slope and the vehicle speed or output shaft rotation. When the area determined by the number and the downhill control execution area enter the downhill control execution area, it is a control for performing a downshift to a shift stage in which the engine braking is effective.

FIG. 4 schematically shows a map for judging a downhill road. In the example shown here, a threshold value used when the driving direction is output-oriented and a map used when the driving direction is non-output-oriented. The one with the threshold used and is shown.
That is, in FIG. 4, the line with the symbol A shows the threshold value adopted in the output directing, and the line with the symbol B shows the threshold value adopted in the non-output directing. Since the threshold value is set to a lower gradient side than that in the non-output direction, it is easy to execute the downhill control in the output direction.

In the above-described control device, when the driving direction is the output direction, the slip control of the lockup clutch 2 is prohibited and the released state is maintained. That is, by releasing the lockup clutch 2, the torque converter 2 can perform the torque increasing action and increase the driving force of the vehicle. On the other hand, when the driving direction is the non-output direction, the slip control is permitted. This is because the engine speed is maintained high by the inertial force input from the wheel side during deceleration to perform fuel cut and improve fuel efficiency. Whether or not the slip control of the lockup clutch 2 is possible is determined based on the driving direction determined by the above-mentioned neural network. However, in the above control device according to the present invention, when downhill control is executed. The lockup clutch 2 is controlled differently from the above.

FIG. 1 is a flowchart showing an example of the control. First, it is judged whether or not the downhill control is being executed (step 1). In this downhill control, it is determined based on various data that the road surface has a downhill slope, and that the traveling area determined by the downhill slope and the output shaft rotation number is within the downhill control execution area shown in FIG. Further, for example, when it is detected that the vehicle is traveling at the fourth speed, the throttle is fully closed, and the brake operation is detected. Specifically, it is downshifted to the third speed where engine braking works. The step 1 corresponds to the downhill control determining means in claim 1.

If the determination in step 1 is negative, the routine is exited without performing any control, and if the determination is affirmative, it is determined whether or not the driving direction is the output direction (step 2). . This corresponds to the driving-direction determining means of claim 1, and is determined by the above-mentioned neural network. However, depending on the configuration of the automatic transmission or the system provided in the electronic control device, the determination may be performed by a system other than the neural network. What is acceptable is as described above.

If the driving orientation determined in step 2 is output orientation, the deceleration slip control of the lockup clutch 2 at the third speed is permitted (step 3). Specifically, the control flag is set to the deceleration slip permission state. Therefore, the slip control of the lock-up clutch 2 is executed when the output shaft rotational speed is in the region shown by S-3 in FIG. 3 in the traveling state in which the throttle valve is closed.
As a result, when the vehicle is traveling downhill with the throttle valve closed, the torque transmission capacity between the engine and the automatic transmission 1 is secured, and the engine braking force increases.
A feeling of deceleration similar to that during deceleration with the lockup clutch 2 released on a flat road can be obtained. That is, the difference in deceleration feeling between the downhill road and the flat road is eliminated or suppressed. Further, if the driving direction is output-oriented, it is desired that both acceleration and braking are high. If the braking force is increased by performing the deceleration slip control as described above, the drivability during output direction is improved. . The step 3 corresponds to the downhill slip control permission means in claim 1.

On the other hand, if the answer in step 2 is negative because the driving orientation is non-output orientation, the deceleration slip control in the third speed is prohibited (step 4). This is because the gear ratio is increased by shifting to the third speed and an engine braking force corresponding to the gear ratio can be obtained, so that the feeling of deceleration due to deceleration slip control is prevented from becoming excessive.

The above control example is a control example for permitting / not permitting the slip control, and the traveling state such as a high vehicle speed is in a region where the lockup clutch is completely engaged. In this case, the lockup clutch may be completely engaged during the downhill control. Further, the present invention can be applied to a control device for other automatic transmissions such as a 5-speed automatic transmission in addition to the 4-speed automatic transmission, and therefore downhill control is performed to the third speed where engine braking works. Not limited to downshifts. Further, the control for facilitating the downhill control when the output is directed may be implemented by other means such as by correcting the input data instead of changing the threshold value in the map described above.

[0026]

As described above, according to the control device of the first aspect of the present invention, when the driving direction is the output direction for obtaining the driving force having a large driving force and the downshift is performed to the shift stage where the engine braking is effective when the vehicle is traveling on a downhill road. When the vehicle is on the slope road, the slip control of the lock-up clutch, which is prohibited on the flat road, is permitted, so that the engine braking force is larger than that when traveling on the flat road. Therefore, acceleration due to gravitational acceleration when traveling on a downhill road can be suppressed by the engine braking force, and the feeling of deceleration on a flat road and a downhill road can be made equal or similar, and the difference in deceleration feeling and the resulting It is possible to prevent discomfort. Further, since the engine braking force can be increased when the vehicle is descending an output-oriented vehicle that requires high acceleration and braking, the drivability can be improved.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, in the output-oriented state, the downhill control can be easily executed even in the case of the non-output-oriented state. It becomes easier to secure the braking force, and the drivability can be further improved.

[Brief description of drawings]

FIG. 1 is a flow chart showing a control example for permitting slip control during downhill control and output directing by a control device of the present invention.

FIG. 2 is a block diagram for explaining a control system.

FIG. 3 is a diagram showing an example of maps for shift control and lock-up clutch control.

FIG. 4 is a map in which a downhill control area is set for output orientation and non-output orientation.

[Explanation of symbols]

1 automatic transmission 2 lock-up clutch 3 Torque converter 9 Electronic control unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI F16H 59:66 F16H 59:66 (56) References JP-A-60-128027 (JP, A) JP-A-4-4351 (JP , A) JP-A-2-151565 (JP, A) JP-A-6-174074 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60K 41/00-41/28 F16H 59/00-61/24 F16H 61/38-61/64 F16H 63/40-63/48

Claims (2)

(57) [Claims] 1. The slip control of a lock-up clutch arranged in parallel with a hydraulic power transmission device for inputting power to a transmission is performed when a driver's driving direction is an output direction in which a driving force is increased to travel. Is prohibited, and is permitted when the driving direction is non-output direction.It is determined that the control device for the lock-up clutch is performing the control to activate the engine brake as the vehicle travels downhill. Downhill control determining means, driving orientation determining means for determining the driving orientation, and the downhill control determining execution of control to apply engine braking while traveling on a downhill road, and the driving orientation determining means And a downward slope slip control permission unit that permits slip control of the lockup clutch when it is determined that the driving direction of the vehicle is output. Lockup clutch control device. 2. The driving direction determination means further comprises means for facilitating execution of control for applying engine braking during traveling on a downhill when the driving direction determination means determines that the driving direction of the driver is output direction. The control device for the lockup clutch according to claim 1, wherein