KR102507271B1 - Creep control method for vehicle - Google Patents

Abstract

The present invention includes a creep determination step in which the controller determines whether the vehicle is in creep driving; a two-stage creep review step of determining whether the vehicle can creep in two stages when the vehicle is in creep travel; a second-stage creep step of shifting to the second gear and performing the creep driving in the second gear when the controller determines that the second-stage creep driving is possible; and a first-stage creep switching step of switching the controller to perform creep driving in the first stage when a brake is operated during second-stage creep driving.

Description

Vehicle creep control method {CREEP CONTROL METHOD FOR VEHICLE}

The present invention relates to a creep control method of a vehicle, and more particularly, to a creep driving control technology of a vehicle equipped with a transmission that receives engine power through a dry clutch.

AMT (Automated Manual Transmission) uses the Synchromesh Type Shifting Mechanism used in conventional manual transmissions to maximize power transmission efficiency while greatly increasing user convenience through automated shifting. .

The AMT as described above receives power from an engine through a clutch, and mainly uses a dry clutch rather than a wet clutch for a simpler configuration and cost reduction.

In vehicles equipped with an AMT based on the dry clutch, clutch judder and clutch heat have emerged as major technical problems.

In particular, tail-biting driving, which can occur for a long time in the city center, is repeated when the creep speed alone is insufficient to maintain the distance to the vehicle in front, stepping on the accelerator pedal to switch to start driving and immediately lowering the vehicle speed to switch to creep driving. Frequent repetition of the creep driving state and the start driving state tends to cause overheating of the clutch, and in this case, since the clutch compulsory open logic for clutch protection is executed, it becomes a major cause of consumer dissatisfaction.

In addition, clutch judder tends to occur mainly in the range of 700 to 1000 RPM near the idle speed of the engine, so when the vehicle creeps in the first gear, it is mainly generated by clutch heat, etc., resulting in vibration and vibration of the vehicle. This makes the occupants uncomfortable.

For reference, the dry clutch will be simply referred to as a “clutch” below.

The matters described as the background technology of the present invention are only for the purpose of improving the understanding of the background of the present invention, and should not be taken as an admission that they correspond to the prior art already known to those skilled in the art. It will be.

KR 1020140118028 A

The present invention reduces the frequency of clutch forced open situations by reducing the heat generated by the clutch during creep driving of the AMT vehicle, and avoids situations in which vibration and vibration of the vehicle due to clutch judder occur as much as possible. It is an object of the present invention to provide a method for controlling creep of a vehicle to improve driving stability and ride comfort of the vehicle.

The creep control method of the vehicle of the present invention for achieving the above object,

a creep determination step in which the controller determines whether the vehicle is in creep driving;

a two-stage creep review step of determining whether the vehicle can creep in two stages when the vehicle is in creep travel;

a second-stage creep step of shifting to the second gear and performing the creep driving in the second gear when the controller determines that the second-stage creep driving is possible;

a 1st stage creep conversion step of allowing the controller to perform creep driving in 1st stage if a brake is operated during 2nd stage creep driving;

It is characterized in that it is configured to include.

In the step 2 creep review step,

When the actual gradient of the road on which the vehicle is currently driving is less than a predetermined gradient reference value and the current clutch temperature is less than a predetermined reference temperature, it can be determined that the vehicle can creep in 2nd gear.

In the step 1 creep conversion step

In addition to the driver's brake operation, it is possible to switch to perform first-stage creep driving when the vehicle speed is less than a predetermined reference vehicle speed.

a start request determination step of determining that there is a vehicle start request when the driver's accelerator pedal operation exceeds a predetermined reference operation and engine torque exceeds the predetermined reference torque;

a start control step of terminating previous creep control and performing start control when the start request of the vehicle is determined;

It may be configured to further include.

In the second-stage creep step, the creep vehicle speed is set to a second-stage creep vehicle speed higher than that of the first-stage creep driving;

Engine torque may be increased as much as necessary to secure the second-stage creep vehicle speed.

In addition, the creep control method of the vehicle of the present invention to achieve the above object,

while the vehicle is creeping in first gear, shifting to second gear when a predetermined condition is satisfied, and performing second gear creep driving with a goal of a second gear creep vehicle speed higher than the first gear creep vehicle speed;

switching, by the controller, to start control when a driver's request for starting occurs while the vehicle is driving in first-stage creep or driving in second-stage creep;

It is characterized in that it is configured to include.

It is determined that the conditions for switching from the first-stage creep driving to the second-stage creep driving are satisfied when the actual gradient of the road on which the vehicle is currently driving is less than a predetermined gradient reference value and the current clutch temperature is less than a predetermined reference temperature. can do.

While the controller is performing second-stage creep driving, when the BPS signal is turned on according to the operation of the brake pedal and the vehicle speed is less than a predetermined reference vehicle speed, the controller shifts to first gear and performs first-stage creep driving.

The driver's request for start can be determined as the driver's request for start when the APS signal according to the operation of the accelerator pedal exceeds a value corresponding to a predetermined reference manipulation amount and the corresponding engine torque exceeds the predetermined reference torque. there is.

The present invention reduces the frequency of clutch forced open situations by reducing the heat generated by the clutch during creep driving of the AMT vehicle, and avoids situations in which vibration and vibration of the vehicle due to clutch judder occur as much as possible. In this way, it is possible to improve driving stability and riding comfort of the vehicle.

1 is a configuration diagram of a vehicle equipped with an AMT to which the present invention can be applied;
2 is a flowchart illustrating an embodiment of a method for controlling creep of a vehicle according to the present invention.

1 is a configuration diagram of a vehicle equipped with an AMT to which the present invention can be applied, power of an engine E is input to the AMT through a clutch CL, and a controller CLR operates through a clutch actuator CA. It is configured to perform shifting by controlling the clutch CL and controlling the AMT through the shift actuator SA, and the power passing through the AMT is transmitted to the drive wheels W through the differential DF.

The controller (CLR) is connected to an accelerator position sensor (APS) to receive an input of the driver's accelerator pedal operation amount, and to a brake pedal position sensor (BPS) to receive an input of the brake pedal operation amount. A gradient sensor (GS) capable of detecting the gradient is connected.

For reference, creep driving refers to a state in which the driver drives at a vehicle speed of around 5Km/h in a state where the driver does not operate the accelerator and brake pedals. It is based on adjusting the slip amount of the clutch.

Since general creep driving is implemented with the first gear of the transmission, as will be described later, it is not specifically limited to 2-speed creep driving, and simply referred to as creep driving means 1-speed creep driving. The vehicle speed h means the first stage creep vehicle speed.

In addition, starting control, which will be described later, refers to control in which the vehicle is accelerated by gradually engaging the clutch while slipping the clutch so as to follow the target engine (E) speed according to the driver's operation of the accelerator pedal from the stop state or creep driving state.

Referring to FIG. 2 , the creep control method of a vehicle according to the present invention includes a creep determination step ( S10 ) of determining whether the vehicle is creeping by a controller (CLR); a 2-step creep review step (S20) of determining whether the controller (CLR) is capable of creep driving in 2 steps when the vehicle is in creep driving; a second-stage creep step (S30) of shifting to the second gear and performing the creep driving in the second gear when the controller (CLR) determines that the 2-speed creep driving is possible; The controller (CLR) is configured to include a first stage creep switching step (S40) of switching to perform creep driving in the first stage when a brake operation occurs during the second stage creep travel.

In the creep determination step ( S10 ), it is determined whether or not the vehicle is driving in the first gear, which is basically a gear range used when performing the creep driving.

That is, according to the present invention, the controller (CLR) shifts to second gear to perform 2-speed creep driving when a predetermined condition is satisfied while the vehicle is creeping in 1st gear, so that the vehicle quickly passes through a driving area where judder is likely to occur. Thus, it is difficult for the driver to detect vibration or shaking due to the judder, and unnecessary start-up driving is prevented to suppress heat generation of the clutch.

In the 2-stage creep review step (S20), when the actual gradient of the road on which the vehicle is currently driving is less than a predetermined gradient reference value and the current clutch temperature is less than a predetermined reference temperature, it is determined that creep driving is possible in 2 stages. .

That is, when the actual gradient of the road is greater than or equal to the gradient reference value, this is because the shift to second gear is inappropriate because a higher drive torque is required in a climbing situation, and in a situation where the clutch temperature is higher than the reference temperature, additional shifting by shifting is required. This is because it is desirable not to generate clutch slip.

Therefore, it is preferable that the gradient reference value and the reference temperature be set appropriately for the corresponding vehicle model by design through a number of experiments and analyzes according to the above-mentioned purpose.

In the second-stage creep step (S30), the creep vehicle speed is set to a second-stage creep vehicle speed higher than the first-stage creep vehicle speed, and the engine torque is increased as necessary to secure the second-stage creep vehicle speed.

That is, when the first-stage creep vehicle speed is 5 km/h, the second-stage creep vehicle speed is set to 6 to 7 km/h, etc., and in the second-stage creep step (S30), the clutch and engine (E) aim at the second-stage creep vehicle speed. ) is controlled, so that the engine torque can be increased accordingly.

As described above, during first-stage creep driving, when the creep driving is performed with the goal of a higher second-stage creep vehicle speed in the second-stage creep step (S30) through the creep determination step (S10) and the second-stage creep review step (S20), , Even in a situation where it is difficult to follow with the first-stage creep driving and the distance from the vehicle in front must be adjusted by stepping on the accelerator pedal to start driving, the second-stage creep driving eliminates the need for start-up driving, so that start-up and creep driving are repeated. while it occurs, it is to prevent the clutch CL from overheating.

This also has an effect of increasing the driver's convenience by preventing the driver from repeatedly stepping on and releasing the accelerator pedal.

Of course, when it is determined that the vehicle speed is too fast due to the higher second-stage creep vehicle speed as described above or the distance to the vehicle in front is narrowed, the driver steps on the brake pedal, which causes the first-stage creep conversion step (S40) to be performed. , it is converted to first-stage creep driving.

In the first-stage creep switching step (S40), in addition to the driver's brake operation, when the vehicle speed is less than a predetermined reference vehicle speed, the first-stage creep driving is performed.

That is, when the BPS signal is turned on according to the operation of the brake pedal and the vehicle speed is less than a predetermined reference vehicle speed during second-stage creep driving, the vehicle shifts to first gear and performs first-stage creep driving.

This is because it can be determined that the driver certainly has a will to reduce the vehicle speed when the vehicle speed is substantially reduced to a significant level by the driver's brake operation.

Therefore, it is preferable to appropriately set the reference vehicle speed in terms of design through experimentation and analysis according to the above-mentioned purpose.

On the other hand, as described above, if the condition of the second stage creep review step (S20) is satisfied during first stage creep driving, the engine speed is changed to 700 to 700, where judder is mainly generated, by immediately switching to the second stage creep step (S30). Since it leaves the 1000 RPM area and changes to around 1500 RPM, it is possible to avoid the driving area where judder is likely to occur as quickly as possible, thereby significantly reducing the occurrence of judder in the vehicle.

Meanwhile, in the present invention, when the driver's accelerator pedal operation amount exceeds a predetermined reference operation amount and the engine torque exceeds the predetermined reference torque during first-stage creep driving or second-stage creep driving as described above, the vehicle start request An oscillation request determination step (S50) of determining that there is; When the start request of the vehicle is determined, it is configured to further include an start control step (S60) of terminating previous creep control and performing start control.

That is, when the driver steps on the accelerator pedal and the engine torque exceeds a certain level, whether during first-stage creep driving or second-stage creep driving, it is determined as the driver's will to start, and creep control is terminated accordingly, start control is performed, and the vehicle is to accelerate

The driver's start request is determined as the driver's start request when the APS signal according to the accelerator pedal operation exceeds a value corresponding to a predetermined reference manipulation amount and the engine torque accordingly exceeds the predetermined reference torque. , The reference manipulated variable and the reference torque are determined by design through a number of experiments and analyzes according to the above purpose.

Although the present invention has been shown and described in relation to specific embodiments, it is known in the art that the present invention can be variously improved and changed without departing from the technical spirit of the present invention provided by the claims below. It will be self-evident to those skilled in the art.

E; engine
CL; clutch
CLR; controller
CA; clutch actuator
SA; gear shift actuator
D-F; differential
W; drive wheel
GS; gradient sensor
S10; Creep judgment stage
S20; Stage 2 creep review
S30; Step 2 creep
S40; Step 1 Creep Conversion
S50; Determination stage of launch request
S60; Oscillation control step

Claims (9)

a creep determination step in which the controller determines whether the vehicle is in creep driving;
a two-stage creep review step of determining whether the vehicle can creep in two stages when the vehicle is in creep travel;
a second-stage creep step of shifting to the second gear and performing the creep driving in the second gear when the controller determines that the second-stage creep driving is possible;
a 1st stage creep conversion step of allowing the controller to perform creep driving in 1st stage if a brake is operated during 2nd stage creep driving;
It is composed of,
In the step 2 creep review step,
Determining that creep driving is possible in 2nd gear when the actual gradient of the road on which the vehicle is currently traveling is less than a predetermined gradient reference value and the current clutch temperature is less than a predetermined reference temperature
Creep control method of a vehicle, characterized in that. delete The method according to claim 1, in the step 1 creep conversion step
In addition to the driver's brake operation, switching to perform first-stage creep driving when the vehicle speed is less than a predetermined reference vehicle speed
A creep control method of a vehicle, characterized in that. The method of claim 1,
a start request determination step of determining that there is a vehicle start request when the driver's accelerator pedal operation exceeds a predetermined reference operation and engine torque exceeds the predetermined reference torque;
a start control step of terminating previous creep control and performing start control when the start request of the vehicle is determined;
Creep control method of a vehicle, characterized in that configured to further include. The method of claim 1,
In the second-stage creep step, the creep vehicle speed is set to a second-stage creep vehicle speed higher than that of the first-stage creep driving;
Increasing engine torque as necessary to secure the 2nd stage creep vehicle speed
Creep control method of a vehicle, characterized in that. while the vehicle is creeping in first gear, shifting to second gear when a predetermined condition is satisfied, and performing second gear creep driving with a goal of a second gear creep vehicle speed higher than the first gear creep vehicle speed;
switching, by the controller, to start control when a driver's request for starting occurs while the vehicle is driving in first-stage creep or driving in second-stage creep;
It is composed of,
It is determined that the conditions for switching from the first-stage creep driving to the second-stage creep driving are satisfied when the actual gradient of the road on which the vehicle is currently driving is less than a predetermined gradient reference value and the current clutch temperature is less than a predetermined reference temperature. to do
Creep control method of a vehicle, characterized in that. delete The method of claim 6,
While the controller performs second-stage creep driving, when the BPS signal according to brake pedal operation is turned on and the vehicle speed is less than a predetermined reference vehicle speed, shifts to first gear and performs first-stage creep driving.
A creep control method of a vehicle, characterized in that. The method of claim 6,
The driver's start request is to determine that the driver's start request exists when the APS signal according to the accelerator pedal operation exceeds a value corresponding to a predetermined reference manipulation amount and the corresponding engine torque exceeds the predetermined reference torque.
Creep control method of a vehicle, characterized in that.

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