KR20190072344A - Control method and appratus for maintaining deceleration sensitivity of mild hybrid electric vehicle - Google Patents

Abstract

According to an embodiment of the present invention, a control method for maintaining deceleration sensitivity of a mild hybrid electric vehicle comprises the following steps of: determining whether a coasting condition is satisfied; turning off an engine when the coasting condition is satisfied, and enabling the engine, a transmission, and a clutch between vehicle drive shafts to be left; detecting a deceleration ratio of the vehicle; lowering the deceleration ratio through applying a frictional force when the deceleration ratio is greater than a reference deceleration ratio; and raising the deceleration ratio through increasing torque when the deceleration ratio is smaller than the reference deceleration ratio.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a control method and apparatus for maintaining a deceleration of a mild hybrid vehicle,

The present invention relates to a method and apparatus for maintaining the deceleration of a mild hybrid vehicle.

As is known, a hybrid electric vehicle uses an internal combustion engine together with a battery power source. That is, the hybrid vehicle uses the power of the internal combustion engine and the power of the motor in an efficient combination.

Hybrid vehicles can be classified into a mild type and a hard type according to the power sharing ratio between the engine and the motor. A hybrid vehicle of a mild type (hereinafter, referred to as a mild hybrid vehicle) is provided with a mild hybrid starter & generator (MHSG) that starts the engine instead of the alternator or generates power by the output of the engine. The hybrid vehicle of the hard type is provided with a starter generator that starts the engine or generates power by the output of the engine and a drive motor that drives the vehicle.

Mild hybrids can assist the engine torque according to driving conditions using the MHSG and can charge the battery (for example, a 48 V battery) through regenerative braking. As a result, the fuel efficiency of the mild hybrid vehicle can be improved.

The main method for reducing fuel consumption in a mild hybrid vehicle is to separate the fuel into fine particles during coasting and to turn off the engine. In the vehicle with the E- clutch, the engine, the transmission and the vehicle drive shaft are separated from each other, ) Can be further reduced to improve the performance of the driving force.

However, when the deceleration of the vehicle is not consistent due to the surrounding environment (for example, gradient of the road, rolling resistance, etc.) at the deceleration of the vehicle, there is a problem that the driver feels anxiety.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a control method and apparatus for maintaining a feeling of deceleration during driving of a mild hybrid vehicle.

A method of controlling a deceleration of a mild hybrid vehicle according to an exemplary embodiment of the present invention includes the steps of determining whether a vehicle is in a deceleration condition, The method comprising the steps of: releasing the clutch between the vehicle drive axles; sensing a reduction ratio of the vehicle; adjusting the reduction ratio by applying a frictional force when the reduction ratio is larger than the reference reduction ratio; And if it is smaller, adjusting the speed ratio up through torque increase.

The step of determining whether or not the driving state satisfies the driving state may be determined on the basis of the position value of the accelerator pedal, the position value of the brake pedal, the speed of the mild hybrid vehicle, and the gradient of the road.

In the step of sensing the reduction ratio of the vehicle, the reduction ratio of the vehicle can be detected through the vehicle speed at the time of turning off the engine and the engine speed (rpm).

The step of adjusting the reduction ratio may be performed when the value obtained by subtracting the reference reduction ratio from the reduction ratio is larger than the first difference value.

In the step of adjusting the reduction ratio, the greater the value obtained by subtracting the reference reduction ratio from the reduction ratio, the larger the application of the frictional force may be.

The step of adjusting the reduction gear ratio may be performed when the value obtained by subtracting the reference reduction gear ratio from the reduction gear ratio is smaller than a second difference value that is smaller than the first difference value.

In the step of adjusting the reduction ratio, the torque increase may become larger as the value obtained by subtracting the reference reduction ratio from the reduction ratio is smaller.

The method of controlling the deceleration of the mild hybrid vehicle according to the embodiment of the present invention includes the step of maintaining the driving of the vehicle when the value obtained by subtracting the reference reduction ratio from the reduction ratio is between the first difference value and the second difference value .

The method for controlling the deceleration of the mild hybrid vehicle according to the embodiment of the present invention includes the steps of engaging the clutch with the E-clutch control and regenerative braking with the MHSG reverse rotation control And increasing the load.

The method for controlling the deceleration of the mild hybrid vehicle according to the embodiment of the present invention includes the steps of engaging the clutch with the E-clutch control after the step of adjusting the reduction ratio upward, and increasing the torque of the MHSG, And increasing the acceleration.

An apparatus for controlling a deceleration of a mild hybrid vehicle according to an embodiment of the present invention includes an accelerator pedal position sensor for measuring a position value of an accelerator pedal, a brake pedal position sensor for measuring a position value of the brake pedal, A vehicle speed sensor for measuring a speed, a gradient sensor for measuring a gradient of a road, and a control unit for comparing the reduction ratio of the vehicle with the reference reduction ratio, adjusting the reduction ratio by applying a frictional force according to the comparison result, Wherein the controller adjusts the reduction ratio to a lower value when the value obtained by subtracting the reference reduction ratio from the reduction ratio is larger than the first difference value, If the second difference value is smaller than the first difference value, the reduction ratio is adjusted upward.

The control unit may control to maintain the driving force when the value obtained by subtracting the reference reduction ratio from the reduction ratio is between the first difference value and the second difference value.

The control unit may engage the clutch with the E-clutch control to adjust the reduction ratio downward, perform the regenerative braking with the MHSG reverse rotation control, and increase the load.

The controller may engage the clutch with the E-clutch control to increase the torque of the MHSG or increase the acceleration of the vehicle in order to adjust the reduction ratio up.

As described above, according to the embodiment of the present invention, it is possible to maintain a consistent sense of deceleration during deceleration of the mild hybrid vehicle, thereby preventing the driver from feeling technical anxiety about the engine-off state and the non- The reliability of the vehicle can be improved.

1 is a block diagram showing a mild hybrid vehicle according to an embodiment of the present invention.
2 is a block diagram illustrating a deceleration reduction control device of a mild hybrid vehicle according to an embodiment of the present invention.
3A and 3B are flowcharts of a method for controlling the deceleration of a mild hybrid vehicle according to an embodiment of the present invention.
FIG. 4 is a graph illustrating a downshift adjustment of a reduction ratio to explain a deceleration reduction control method of a mild hybrid vehicle according to an embodiment of the present invention.
FIG. 5 is a graph illustrating a case where the deceleration ratio is upwardly adjusted in order to explain a deceleration reduction control method of a mild hybrid vehicle according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are given the same reference numerals throughout the specification.

In addition, since the components shown in the drawings are arbitrarily shown for convenience of explanation, the present invention is not necessarily limited to those shown in the drawings.

Hereinafter, a deceleration reduction control device for a mild hybrid vehicle and a mild hybrid vehicle according to an embodiment of the present invention will be described with reference to Figs. 1 and 2. Fig.

FIG. 1 is a block diagram showing a mild hybrid vehicle according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a deceleration reduction control device of a mild hybrid vehicle according to an embodiment of the present invention.

1, a mild hybrid vehicle according to an embodiment of the present invention includes an engine 10, a transmission 20, a mild hybrid starter & generator (MHSG) 30, a first battery 40, An apparatus 80, and a wheel 90.

The engine 10 converts chemical energy into mechanical energy by burning fuel and air.

The power transmission of the mild hybrid vehicle is such that the torque of the engine 10 is transmitted to the input shaft of the transmission 20 and the torque output from the output shaft of the transmission 20 is transmitted to the axle via the differential gear device 80. The mild hybrid vehicle is driven by the torque of the engine 10 by rotating the wheel 90 with the axle.

The MHSG 30 converts electrical energy into mechanical energy or mechanical energy into electrical energy. That is, the MHSG 30 can start the engine 10 or generate power by the output of the engine 10. [ Further, the MHSG 30 can assist the torque of the engine 10. [ The mild hybrid vehicle can utilize the torque of the MHSG 30 as auxiliary power while making the combustion torque of the engine 10 the main driving force. The engine 10 and the MHSG 30 may be connected via a belt 32.

The first battery 40 may be charged via electricity supplied to the MHSG 30 or recovered via the MHSG 30 in the regenerative braking mode. The first battery 40 may be a 48V battery. The mild hybrid vehicle includes a low voltage DC-DC converter (LDC) 50 for converting the voltage supplied from the first battery 40 to a low voltage and a second battery 50 for supplying a low voltage to the vehicle electric component 70 using the low voltage. (60). The second battery 60 may be a 12V battery.

The engine 10 may include a plurality of combustion chambers 11 into which fuel and air are introduced, an ignition device 12 that ignites the fuel and air introduced into the combustion chamber 11, and an injector 13 that injects fuel have. The engine 10 is connected to the intake manifold 14 to receive air into the combustion chamber 11 and the exhaust gas generated in the combustion process is collected in the exhaust manifold 15 and then discharged to the outside of the engine 10. [ The injector 13 may be mounted in the combustion chamber 11 or in the intake manifold 14.

The throttle valve 16 is disposed in an intake line formed to supply air to the intake manifold 14. The flow of the air supplied to the intake manifold 14 is controlled in accordance with the amount of opening of the throttle valve 16.

The exhaust pipe 17 is connected to the exhaust manifold 15 to exhaust the exhaust gas to the outside of the vehicle. A catalyst 18 may be mounted on the exhaust pipe 17 to remove hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas.

2, the apparatus for controlling the deceleration of the mild hybrid vehicle according to the embodiment of the present invention includes an accelerator pedal position sensor 2, a brake pedal position sensor 4, a vehicle speed sensor 6, A gradient sensor 8, an E-clutch 28 and a controller 100. As shown in FIG.

The accelerator pedal position sensor 2 measures the position value of the accelerator pedal and transmits a signal to the controller 100. When the accelerator pedal is fully depressed, the position value of the accelerator pedal is 100%, and when the accelerator pedal is not depressed, the position value of the accelerator pedal is 0%.

The brake pedal position sensor 4 measures the position value of the brake pedal and transmits a signal to the controller 100. When the brake pedal is fully depressed, the position value of the brake pedal is 100%, and when the brake pedal is not depressed, the position value of the brake pedal is 0%.

The vehicle speed sensor 6 measures the speed of the mild hybrid vehicle and transmits a signal to the controller 100.

The gradient sensor 8 measures the gradient of the road and transmits a signal to the controller 100.

The E-clutch 28 connects or disconnects the engine 10 and the transmission 20 and the clutch 25 between the vehicle drive shaft.

The controller 100 compares the reduction ratio of the vehicle with the reference reduction ratio, adjusts the reduction ratio by applying the frictional force, or adjusts the reduction ratio by increasing the torque.

The reduction ratio of the vehicle can be sensed through the vehicle speed at the time of turning off the engine 10 and the engine speed (rpm). The reference reduction gear ratio can be set to a value that is deemed desirable by a person skilled in the art through experiments.

When the value obtained by subtracting the reference reduction ratio from the reduction ratio is smaller than the first difference B, the controller 100 adjusts the reduction ratio to a lower value, and when the value obtained by subtracting the reference reduction ratio from the reduction ratio is smaller than the first difference B If the second difference value A is smaller than the second difference value A, the reduction ratio can be adjusted upward.

In addition, the controller 100 can control to maintain the driving force when the value obtained by subtracting the reference reduction ratio from the reduction ratio is between the first difference value A and the second difference value B.

At this time, the first difference value B and the second difference value A can be set to values that are deemed desirable by those skilled in the art through experiments.

The control unit 100 can also increase the load by engaging the clutch 25 under the control of the E-clutch 28 and regenerative braking by the reverse rotation control of the MHSG 30 in order to adjust the reduction ratio downward.

The control unit 100 can also increase the torque of the MHSG 30 or increase the acceleration of the vehicle by engaging the clutch 25 under the control of the E-clutch 28 to adjust the reduction ratio upward.

The controller 80 may be implemented as one or more processors that operate according to a set program, and the set program may be implemented by performing each step included in the deceleration reduction control method of the mild hybrid vehicle according to an embodiment of the present invention Lt; RTI ID = 0.0 > commands. ≪ / RTI >

FIG. 3A and FIG. 3B are flowcharts of a method of controlling the deceleration of the mild hybrid vehicle according to the embodiment of the present invention. FIG. 4 is a flowchart illustrating a method of controlling the deceleration of the mild hybrid vehicle according to the embodiment of the present invention. FIG. 5 is a graph illustrating a case where the deceleration ratio is upwardly adjusted in order to explain a deceleration reduction control method of a mild hybrid vehicle according to an embodiment of the present invention. Referring to FIG.

Referring to FIGS. 3A and 3B, in the deceleration reduction control method of the mild hybrid vehicle according to the embodiment of the present invention, the controller 100 first determines whether the driving condition is satisfied (S101).

The controller 100 can determine whether the hit driving condition is satisfied based on the position value of the accelerator pedal, the position value of the brake pedal, the speed of the mild hybrid vehicle, and the gradient of the road. For example, the driving state of the vehicle is such that the position value of the accelerator pedal is the first set position value (for example, 0%) and the position value of the brake pedal is the second set position value (for example, 0% , A case where the speed of the mild hybrid vehicle is equal to or higher than the first set speed (for example, 30 KPH) and the gradient of the road is the set gradient range (for example, between -4% and 4%) .

Thereafter, when the torque driving condition is satisfied, the controller 100 turns off the engine 10 and releases the clutch between the engine 10 and the transmission 20 and the vehicle drive shaft (S102).

Thereafter, the controller 100 senses the reduction ratio of the vehicle (S103). The reduction ratio of the vehicle can be sensed through the vehicle speed at the time of turning off the engine 10 and the engine speed (rpm).

Thereafter, the reduction ratio of the vehicle is compared with the reference reduction ratio (S104). The reference reduction gear ratio can be set to a value that is deemed desirable by a person skilled in the art through experiments. For example, the reference reduction ratio can be set within a reduction ratio range that allows the driver to feel a sense of stability as compared with the reduction ratio in the vehicle speed at the time of turning off the engine 10 and the revolution speed of the engine 10.

Thereafter, if the reduction ratio is larger than the reference reduction ratio, the reduction ratio is adjusted downward by applying the friction force (S108). The step of decreasing the reduction ratio (S108) may be performed when the value obtained by subtracting the reference reduction ratio from the reduction ratio is larger than the first difference value B (S105). At this time, the larger the value obtained by subtracting the reference reduction gear ratio from the reduction gear ratio, the larger the application of the frictional force can be.

If the reduction ratio is smaller than the reference reduction ratio, it is determined whether the value obtained by subtracting the reference reduction ratio from the reduction ratio is smaller than the second difference value A which is smaller than the first difference value B (S106) If the value obtained by subtracting the reference reduction gear ratio is smaller than the second difference value A, the reduction ratio is adjusted upward by increasing the torque (S111). At this time, the smaller the value obtained by subtracting the reference reduction ratio from the reduction ratio, the larger the torque increase can be.

If the value obtained by subtracting the reference reduction ratio from the reduction ratio is larger than the second difference (A), adjustment of the reduction ratio is not performed but the driving of the vehicle is maintained (S107).

On the other hand, if the value obtained by subtracting the reference reduction ratio from the reduction ratio is between the first difference value A and the second difference value B, the driving force is maintained (S107).

After the step of decreasing the reduction ratio (S108), the clutch 25 is engaged by the control of the E-clutch 28, the regenerative braking is performed by the reverse rotation control of the MHSG 30, and the load is increased. Thereafter, the process returns to the step of sensing the reduction ratio again (S103).

Further, after the step S111 of increasing the reduction ratio, the clutch 25 is engaged under the control of the E-clutch 28 to increase the torque of the MHSG 30 or increase the acceleration of the vehicle. Thereafter, the process returns to the step of sensing the reduction ratio again (S103).

As shown in Fig. 4, the driving range of the driving force is set from the time of turning off the engine 10 to the time of stopping the vehicle, and the slope of the RPM at the time of turning off the engine 10 is set as the current reduction ratio. The reference reduction ratio is set to a value that is determined by a person skilled in the art through experimentation, and can be set to a reduction ratio such that the driver can feel a sense of stability. When the current reduction ratio is larger than the reference reduction ratio and the value obtained by subtracting the reference reduction ratio from the current reduction ratio is larger than the first difference value B, the reduction ratio is adjusted downward by applying the frictional force.

As shown in FIG. 5, when the current reduction ratio is smaller than the reference reduction ratio and the value obtained by subtracting the reference reduction ratio from the current reduction ratio is smaller than the second difference value A, the reduction ratio is increased by increasing the torque.

As described above, according to the embodiment of the present invention, it is possible to maintain a consistent sense of deceleration during the deceleration of the mild hybrid vehicle, so that the driver can be prevented from technical anxiety about the engine off state and the non- It is possible to improve the reliability of the apparatus.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

10: engine 20: transmission
30: MHSG 40: First battery
50: LDC 60: Second battery
70: Vehicle electric component 80: Differential gear device
90: Wheel 100: Controller

Claims (14)

Determining whether the driving condition of the vehicle is satisfied;
Turning off the engine and releasing the clutch between the engine and the transmission and the vehicle drive shaft when the torque running condition is satisfied;
Sensing a reduction ratio of the vehicle;
If the reduction ratio is larger than the reference reduction ratio, adjusting the reduction ratio by applying a frictional force; And
And adjusting the reduction ratio by increasing the torque when the reduction ratio is smaller than the reference reduction ratio. The method of claim 1,
Wherein the step of determining whether the driving condition satisfies the driving-
Wherein the deceleration of the mild hybrid vehicle is determined based on the position value of the accelerator pedal, the position value of the brake pedal, the speed of the mild hybrid vehicle, and the gradient of the road. The method of claim 1,
In the step of sensing the reduction ratio of the vehicle,
Wherein the deceleration ratio of the vehicle is sensed through the vehicle speed at the time of turning off the engine and the engine speed (rpm). The method of claim 1,
The step of adjusting the reduction ratio downward may include:
Wherein the control is performed when the value obtained by subtracting the reference reduction ratio from the reduction ratio is larger than the first difference value (B). 5. The method of claim 4,
In the step of lowering the reduction ratio,
Wherein the frictional force is further increased as the value obtained by subtracting the reference reduction ratio from the reduction ratio is greater. The method of claim 5,
The step of adjusting the gear ratio upwards comprises:
Wherein the reduction ratio is performed when the value obtained by subtracting the reference reduction ratio from the reduction ratio is smaller than a second difference value (A) that is smaller than the first difference value (B). The method of claim 6,
In the step of adjusting the gear ratio up,
Wherein the torque increase is larger as the value obtained by subtracting the reference reduction ratio from the reduction ratio is smaller. 8. The method of claim 7,
Further comprising the step of: maintaining a driving state of the vehicle when the value obtained by subtracting the reference reduction ratio from the reduction ratio is between the first difference value (A) and the second difference value (B) . The method of claim 1,
After the lowering of the reduction ratio,
Engaging the clutch with E-clutch control; And
MHSG reverse rotation control to increase the load. The method of claim 1,
After the step of adjusting the gear ratio up,
Engaging the clutch with E-clutch control; And
Further comprising the step of increasing the torque of the MHSG or increasing the acceleration of the vehicle. An accelerator pedal position sensor for measuring the position value of the accelerator pedal;
A brake pedal position sensor for measuring the position value of the brake pedal;
A vehicle speed sensor for measuring the speed of the mild hybrid vehicle;
A gradient sensor for measuring the gradient of the road; And
And a controller for comparing the reduction ratio of the vehicle with a reference reduction ratio and adjusting the reduction ratio by applying a frictional force according to a result of the comparison, or adjusting the reduction ratio by increasing a torque,
The controller comprising:
And when the value obtained by subtracting the reference reduction ratio from the reduction ratio is larger than the first difference value B,
And adjusts the reduction ratio to be increased when the value obtained by subtracting the reference reduction ratio from the reduction ratio is smaller than a second difference value (A) that is smaller than the first difference value (B). 12. The method of claim 11,
Wherein,
And controls to maintain the driving of the vehicle when the value obtained by subtracting the reference reduction ratio from the reduction ratio is between the first difference value (A) and the second difference value (B). 12. The method of claim 11,
Wherein,
Wherein the clutch is engaged with the E-clutch control to adjust the reduction ratio to a lower level, and the regenerative braking is performed by the MHSG reverse rotation control to increase the load. 12. The method of claim 11,
Wherein,
In order to adjust the reduction ratio up,
And the clutch is engaged with the E-clutch control, thereby increasing the torque of the MHSG or increasing the acceleration of the vehicle.

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