KR102616240B1 - Device and method for improving the starting and accelerating performance of a vehicle based on temperature - Google Patents

Abstract

The method for improving starting and acceleration performance of a vehicle according to the present invention includes receiving a torque command from a driver, calculating a reduction ratio from the maximum transmittable torque, and calculating the maximum torque of a wheel, and when the received torque is greater than the maximum torque. The wheel torque is configured to include being limited to the maximum torque. According to this configuration of the present invention, wheel slip can be suppressed and energy loss can be prevented.

Description

Device and method for improving vehicle start and acceleration performance based on temperature {Device and method for improving the starting and accelerating performance of a vehicle based on temperature}

The present invention relates to an apparatus and method for improving starting and acceleration performance of a vehicle based on temperature. More specifically, in the case of electric vehicles or high-performance vehicles with excellent initial torque, unlike internal combustion engines, the initial torque (torque at start or rapid acceleration) is The need for control is great, and rather than braking the driving force that has already been generated after the fact, the friction characteristics of tires and the road surface according to the outside temperature are predicted in advance and the start of electric vehicles and high-performance vehicles is controlled in advance to prevent output exceeding the maximum torque. /Relates to an apparatus and method for improving acceleration performance.

In general, unlike internal combustion engine vehicles, electric vehicles are vehicles that run using a motor instead of an engine and a battery instead of fuel. Due to the nature of controlling the motor, they have the advantage of being able to maximize initial launch torque compared to internal combustion engine vehicles.

However, since electric vehicles can produce the maximum torque of the motor as desired without any restrictions when accelerating at full accelerator (WOT), they are more vulnerable to wheel slip compared to internal combustion engine vehicles when starting/accelerating the vehicle.

For example, in the case of electric vehicles, there are two problems with initial torque. First, because the initial torque is large upon departure, starting performance, such as wheel slip, may be significantly reduced. Another problem is that the initial torque is large during rapid acceleration while driving, which causes problems in acceleration performance, such as wheel slipping.

Conventionally, a driving force is generated in response to such wheel slip, and in order to control the generated driving force, the torque is limited and a braking force is applied to the drive shaft.

For example, when driving a vehicle, the difference in wheel speed between the front and rear wheels can be detected through a wheel speed sensor. If the wheel speed difference between the front and rear wheels exceeds a predetermined standard value, it is determined that wheel slip has occurred on the front or rear wheels, and wheel slip is suppressed by reducing the wheel speed of the front or rear wheels.

However, according to this control method, since the driving force is controlled in a feedback-back manner using the deviation of the wheel speed of the front or rear wheels, it is bound to appear as a loss from the energy point of view. The initial torque is excellent, so it is very difficult to properly respond to oscillation and acceleration situations that have already occurred in a short period of time during start-up or rapid acceleration.

Korean Patent No. 10-1890440

Therefore, the purpose of the present invention is to use a feed-forward control method because the loss of driving force due to wheel slip is inevitable when the above-described feedback control is performed only after wheel slip occurs (e.g., wheel speed difference between the front and rear wheels). To provide a device and method for improving the start/acceleration performance of an electric vehicle or high-performance vehicle that can limit the maximum torque of the motor.

Another object of the present invention is to suppress wheel slip in order to stably control the initial starting performance, considering the starting/accelerating performance of an electric vehicle running using a motor and reducer instead of a transmission, which is raised as the main cause of such wheel slip. The aim is to provide a device and method for improving the start/acceleration performance of an electric vehicle or high-performance vehicle that can utilize the friction characteristics of the tires and the road surface.

Another object of the present invention is a device for improving start/acceleration performance of an electric vehicle or high-performance vehicle that can use the outdoor temperature information most suitable for quantitatively determining the friction characteristics among various parameters that can calculate the friction characteristics of the road surface and tires; and It provides a method.

According to the features of the present invention for achieving the above-mentioned object, the vehicle start/acceleration performance improvement device of the present invention includes a temperature sensor that detects the outside temperature, and a maximum torque by calculating a reduction ratio according to the outside temperature. and a maximum torque determination unit that determines the wheel torque and limits the wheel torque to the maximum torque when the driver's torque command is greater than the maximum torque.

According to another feature of the present invention, the method of improving the starting/accelerating performance of a vehicle of the present invention is to prevent wheel slip during initial starting or rapid acceleration during low-speed driving, including a torque control step during starting. , and a torque control step when driving, wherein the torque control step when starting includes controlling the wheel torque when a stationary vehicle starts and wheel torque is generated, and the torque control step when driving includes: and controlling the wheel torque when the vehicle reaches a certain speed after starting.

According to another feature of the present invention, the method for improving start/acceleration performance of a vehicle of the present invention includes the steps of receiving a torque command from the driver, calculating the maximum torque of the wheel by calculating the deceleration ratio from the maximum transmittable torque, and limiting wheel torque to the maximum torque when the received torque is greater than the maximum torque.

As described above, according to the configuration of the present invention, the following effects can be expected.

In the case of electric vehicles or high-performance vehicles with excellent initial torque, they generate torque greater than the friction between the tires and the road surface, which eventually causes wheel slip, which reduces starting performance at initial start, reduces acceleration performance during low-speed driving, and results in energy loss. Considering the initial torque performance of these vehicles, in order to prevent wheel slip when starting or accelerating, we quantitatively calculate the friction characteristics of the friction force between the tire and the road surface depending on the external temperature, and calculate the maximum By reflecting this in the torque decision, initial launch performance and acceleration performance can be improved, energy loss can be minimized, and driver anxiety caused by excessive torque increase, especially during launch or acceleration, can be alleviated, thereby meeting the consumer's desire for safety. You can.

1 is a block diagram of a device for improving starting and acceleration performance of a vehicle based on temperature according to the present invention.
Figure 2 is a flowchart of a method for improving starting and acceleration performance of a vehicle based on temperature according to the present invention.
Figure 3 is a graph in which the reduction ratio is determined through the correlation between maximum torque and external temperature according to the present invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. The present embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is not limited. It is provided to fully inform those who have the scope of the invention, and the invention is only defined by the scope of the claims. The sizes and relative sizes of layers and regions in the drawings may be exaggerated for clarity of explanation. Like reference numerals refer to like elements throughout the specification.

Embodiments described herein will be explained with reference to plan and cross-sectional views, which are ideal schematic diagrams of the present invention. Therefore, the shape of the illustration may be changed depending on manufacturing technology and/or tolerance. Accordingly, embodiments of the present invention are not limited to the specific form shown, but also include changes in steps provided according to control conditions. Accordingly, the areas illustrated in the drawings have schematic properties, and the shapes of the areas illustrated in the drawings are intended to illustrate a specific form of the control area and are not intended to limit the scope of the invention.

Hereinafter, a preferred embodiment of the device for improving start/acceleration performance of a vehicle according to the present invention having the above-described configuration will be described in detail with reference to the attached drawings.

Referring to FIG. 1, the vehicle start/acceleration performance improvement device 100 includes a temperature sensor 102 that detects the outside temperature (°C), a wheel speed sensor 112 that detects the wheel speed (rpm), and the outside air temperature (°C). A maximum torque determination unit 110 determines the maximum torque by calculating the reduction ratio according to temperature, and limits the wheel torque to the maximum torque when the driver's torque command is greater than the maximum torque, and compares the wheel speed with the speed of the vehicle An optimal torque determination unit 120 that controls the wheel torque to determine the optimal torque when the speed deviation exceeds the standard value, and a wheel brake unit 130 that controls the wheel torque according to the optimal torque and brakes the drive shaft. Includes.

The control flow that determines the maximum torque based on the outside temperature has a feed-forward method, but the control flow that determines the optimal torque based on the wheel speed sensor and improves the braking force of the drive shaft can take the feed-back method. .

In the case of an electric vehicle, the present invention is intended to improve the starting performance and acceleration performance that occurs during initial starting or acceleration during driving. The present invention predicts the friction state between the vehicle's tires and the road surface in advance and reflects this in determining the maximum torque of the wheel. This is to prevent slip.

Accordingly, the method for improving start/acceleration performance may include both a torque control step (S100) when starting and a torque control step (S200) when driving.

The torque control step when starting (S100) refers to a step of controlling wheel torque when a stationary vehicle starts and wheel torque is generated. This step includes a feed-forward control step.

The torque control step during driving (S200) refers to a step of controlling traction due to the difference in friction force of the road surface when the stopped vehicle starts and reaches a certain speed. This step includes a feedback control step.

In the torque control step (S100) when starting, if the wheel torque is not zero, torque control is activated. Additionally, the parameters are not determined based on wheel speed. However, it is determined by the external environment. For example, the outside air temperature, which can predict the friction state between the tire and the road surface, may be a key parameter according to the measured value of the temperature sensor (102 in FIG. 1).

The torque control step (S200) during driving is performed when the vehicle speed and wheel speed deviation are different than the standard value that causes wheel slip, or when the front and rear wheel speed deviation is greater than the standard value, the wheel speed sensor installed on the wheel (see Figure 2). It can be determined according to the value provided by 1 112).

The above-mentioned situation is not a problem that only occurs during initial rash. In other words, it can be applied even when rapid acceleration is required for high-speed driving while driving.

At this time, the torque control step during acceleration (S300) may include a case where the wheel speed change value is greater than the reference value due to rapid acceleration. If the change in wheel torque is large, wheel slip may occur, so even in this case, the maximum torque may be limited depending on the outside temperature, similar to the torque control stage (S100) during start-up.

Here, the subject of the invention is not only electric vehicles, but also internal combustion engine vehicles when the initial torque is strong. In other words, even in the case of internal combustion engine vehicles, depending on the vehicle type, starting performance is excellent and initial acceleration may be necessary. Additionally, when rapid acceleration is required while driving at a constant speed, the need to control maximum torque does not distinguish between electric vehicles and internal combustion engine vehicles. Accordingly, the above-described steps for improving acceleration performance can also be applied to gasoline engines or diesel engines.

However, here, for convenience of explanation, an electric vehicle driven by a motor will be used as an example.

Referring again to FIG. 2, in the method of improving the start/acceleration performance of an electric vehicle by suppressing wheel slip, the method of improving the start/acceleration performance of an electric vehicle is that the wheel torque of the rapidly accelerating vehicle during initial start or driving is adjusted to the difference between the tires and the road surface. The starting step of performing traction control to prevent the friction force from becoming greater (traction control START), the step of receiving the driver's torque command (S110), and the maximum torque of the motor by calculating the reduction ratio from the maximum transmittable torque. It includes a calculating step (S120), and a step of controlling the wheel torque to a small value by comparing the received torque and the maximum torque (S130).

The step of receiving a torque command (S110) includes a step in which the motor torque is generated according to the torque command and is not zero, that is, the torque is activated. If there is no received torque, traction control ends (traction control END).

At the maximum transmittable torque, the reduction ratio is 1, and the maximum torque becomes less than 1 depending on temperature.

For example, when the maximum transmittable torque reaches its highest peak at a certain temperature (e.g., 70°C), the maximum transmittable torque above or below that temperature ( ) decreases, the reduction ratio ( ) becomes less than 1, and the maximum torque ( ) must also be reduced, so the maximum torque can be controlled to prevent wheel slip as shown in equation (1) below.

......(One)

Therefore, if the maximum torque is greater than the received driver's torque command value, the motor torque can be controlled according to the received command, but on the contrary, if the maximum torque is less than the torque command value, the reduction ratio is determined according to the relevant external temperature, and the deceleration rate is adjusted accordingly. It can be controlled correctively with a maximum torque of . That is, in the former case, the wheel torque is controlled by the received torque, and in the latter case, the wheel torque is controlled by the maximum torque.

Meanwhile, referring to FIG. 3, the maximum torque (Max torque) increases in proportion or decreases in inverse proportion depending on the temperature, so quantitative control is possible. For example, the coefficient of friction between the road surface and tires is proportional starting from approximately 70°C until the temperature approaches, and then tends to be inversely proportional beyond that temperature. When the temperature drops below that starting point, the coefficient of friction between the road surface and the tire gradually decreases, increasing the possibility of wheel slip. Conversely, at temperatures above that temperature, the possibility of wheel slip also increases due to tire expansion, road surface heating, and increased humidity.

Therefore, the relationship between the external temperature and the friction coefficient can be quantitatively calculated, and by controlling the maximum torque according to the friction coefficient, it is possible to control the wheel torque by directly reflecting the slip characteristics during the initial start and acceleration commands of the electric vehicle. In particular, since the degree of attenuation of maximum torque can be predicted in advance according to the external temperature, unnecessary energy consumption can be prevented at the source.

The present invention is intended to prevent full accelerator during acceleration during initial starting or driving, and to control cases that are usually difficult to occur in internal combustion engine vehicles due to the characteristics of electric vehicles with excellent initial torque. However, once the initial torque is controlled, It does not interfere with controlling wheel slip due to the difference in wheel speed between the front and rear wheels.

The present invention considers the relationship between the driver's torque command and the maximum torque according to the outside temperature to control the initial torque and prevent full accelerator using a feed-forward method, and controls the torque so as not to exceed the appropriate torque while driving. For wheel slip that occurs, torque control using a normal feedback-back method can be performed.

Therefore, after the step of reducing the maximum torque or less, a step (S200) of outputting the optimal torque by appropriately modifying the maximum torque according to the wheel torque using the deviation of front and rear and/or left and right wheel speeds may be further included. .

For example, if the difference between the front wheel speed and rear wheel speed measured through the wheel speed sensor provided on each wheel is equal to or greater than the reference value (TBD) (S210), the torque of the front or rear wheels can be controlled by reflecting the degree of deviation. There is (S220). And wheel slip is reduced through drive shaft braking (S230).

If it is not greater than the reference value, traction control is considered completed (S240), and traction control is terminated (traction control END).

As seen above, it is not a feedback-type torque control method based on the difference in wheel speed between the front and rear wheels for the driving force that has already been generated, but rather predicts the friction characteristics of the tire and the road surface according to the outside temperature in advance to control the wheel by exceeding the maximum torque. It can be seen that the technical idea is to improve the start/acceleration performance of electric vehicles and high-performance vehicles by preemptively controlling torque output. Within the scope of the basic technical idea of the present invention, many other modifications will be possible to those skilled in the art.

100: Device for improving vehicle launch and acceleration performance
110: maximum torque determination unit 120: optimal torque determination unit

Claims (10)

A temperature sensor that detects the outside temperature; and
a maximum torque determination unit that determines maximum torque by calculating a reduction ratio according to the outside temperature, and limits wheel torque to the maximum torque when a driver's torque command is greater than the maximum torque;
Including,
At the maximum transmittable torque, the reduction ratio is 1,
The reduction ratio becomes smaller than 1 as temperature changes,
The maximum transmittable torque peaks at a predetermined temperature, the maximum transmittable torque is proportional to the temperature up to the predetermined temperature, and the maximum transmittable torque is inversely proportional to the temperature after the predetermined temperature. and acceleration performance improvement device. According to claim 1,
A wheel speed sensor that detects the wheel speed of the vehicle;
an optimal torque determination unit that compares the wheel speed with the speed of the vehicle and determines an optimal torque by controlling the wheel torque when the speed deviation causes wheel slip; and
An apparatus for improving starting and acceleration performance of a vehicle, comprising a wheel brake unit that controls the wheel torque according to the optimal torque and brakes the drive shaft. According to claim 1,
The vehicle includes an electric vehicle with strong initial torque, an internal combustion locomotive with excellent starting performance that requires initial acceleration, and a gasoline engine or diesel locomotive that requires rapid acceleration while driving. A device for improving starting and acceleration performance of a vehicle. In a method of improving the starting performance of a vehicle to prevent wheel slip during initial starting or acceleration during driving,
Torque control stage during launch; and
Torque control phase during driving;
Including,
The torque control step when starting includes controlling the wheel torque when the stationary vehicle starts and wheel torque is generated,
The driving torque control step includes controlling the wheel torque when the driving vehicle reaches a certain speed after starting,
The torque control step during starting and driving determines the maximum torque by calculating the reduction ratio according to the external temperature detected by the temperature sensor,
At the maximum transmittable torque, the reduction ratio is 1,
The reduction ratio becomes smaller than 1 as temperature changes,
The maximum transmittable torque peaks at a predetermined temperature, the maximum transmittable torque is proportional to the temperature up to the predetermined temperature, and the maximum transmittable torque is inversely proportional to the temperature after the predetermined temperature. and methods for improving acceleration performance. According to claim 4,
In the torque control step when starting, if the wheel torque is not zero, torque control is activated, and the torque control is performed according to the outside temperature that can predict the friction state between the tire and the road surface,
The torque control step during driving improves starting and acceleration performance of the vehicle, wherein the torque control is performed when the speed of the vehicle and the speed difference between each wheel are greater than or equal to a reference value or when the speed difference between the front and rear wheel wheels is greater than or equal to a reference value. method. According to claim 4,
The torque control step during oscillation is,
A method of improving starting and acceleration performance of a vehicle, comprising the step of controlling wheel torque when wheel torque occurs during rapid acceleration for high-speed driving of the vehicle. Receiving a torque command from the driver;
Calculating the maximum torque of the wheel by calculating the reduction ratio from the maximum transmittable torque; and
limiting wheel torque to the maximum torque when the received torque command is greater than the maximum torque;
Including,
The reduction ratio at the maximum transmittable torque is 1,
The reduction ratio becomes smaller than 1 as temperature changes,
The maximum transmittable torque peaks at a predetermined temperature, the maximum transmittable torque is proportional to the temperature up to the predetermined temperature, and the maximum transmittable torque is inversely proportional to the temperature after the predetermined temperature. and methods for improving acceleration performance. delete delete According to claim 7,
After the wheel torque is limited to the maximum torque,
outputting optimal torque to optimize the wheel speed when the speed difference between the vehicle speed and each wheel exceeds a reference value or when the wheel speed difference between the front and rear wheels of the vehicle exceeds the reference value; and
performing drive shaft braking according to the optimal torque;
A method of improving starting and acceleration performance of a vehicle further comprising:

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