KR101826674B1 - Reserve torque securing method for vehicle - Google Patents

Abstract

According to the present invention, a reserve torque securing method for a vehicle comprises the following steps of: determining whether a vehicle is in a state of being idle; calculating necessary reserve torque when the vehicle is in a state of being idle; determining a charging state of a battery; and performing a first strategy to secure the necessary reserve torque by advancing ignition time of an engine while applying power generation torque to a power generation mechanical element as much as the necessary reserve torque when determining that the battery needs to be charged.

Description

[0001] The present invention relates to a reserve torque securing method for vehicle,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for securing a reserve torque in a vehicle, and more particularly, to a method for ensuring a stable and efficient reserve torque through an organic cooperative control of an engine and a generator element.

In a conventional vehicle having a single engine as a single power source, the ignition timing control of the engine has been used as a method of quickly responding to the increase / decrease of the torque in the idle state.

In the case where the engine is in an idle state (state in which the driver does not have a will), the ignition timing of the engine is previously perceived by a predetermined angle or more in order to cope with a request for a rapid increase in torque due to an increase in load of an air flow (air conditioner, When the middle torque increase request is made, the ignition timing advancing is performed so that the torque can be increased rapidly. This is generally referred to as securing a reserve torque using an ignition timing retard (see Fig. 3 (a)).

Such reserve torque is advantageous in that it can respond to a demand for a fast torque increase while stably maintaining the operating state of the engine. However, an artificial ignition timing retardance for ensuring a reserve torque is accompanied by a decrease in the efficiency of the engine due to a decrease in the ignition efficiency of the engine .

On the other hand, in the case of a hybrid system having both an engine and a motor, there is an advantage that torque of the motor can be used when a torque increase request is generated. However, in the micro / mild hybrid system, in which the output of the motor and the capacity of the battery are limited, it is difficult to secure a sufficient reserve torque by driving the motor. Therefore, cooperative control with the engine is further required in order to secure the reserve torque by the motor.

Therefore, there is a need to develop control logic that can efficiently maintain the reserve torque while minimizing fuel consumption loss in the idle state including a hybrid vehicle as well as a general vehicle having the engine as a single power source.

U.S. Patent No. 7,305,965 (registered on December 11, 2007)

It is an object of the present invention to provide a method for ensuring a stable and efficient reserve torque through an organic cooperative control of an engine and a generator element.

A method for securing a reserve torque in a vehicle according to the present invention includes the steps of: determining whether the vehicle is in an idle state; calculating a required reserve torque when the vehicle is in an idle state; And performing a first strategy of applying a power generation torque to the power generation machine element by the required reserve torque and advancing an ignition timing of the engine to secure the required reserve torque when it is determined that charging of the battery is necessary .

According to an embodiment of the present invention, the power generating machine element may be an alternator in a general vehicle or a motor of a hybrid vehicle.

When the required torque, which is not caused by the driver's will, is generated while securing the reserve torque according to the first strategy, the ignition timing of the engine is maintained at the advancing state while the generation torque of the power generation machine element is generated Torque.

Here, the generator element is an alternator. When it is determined that the battery is not required to be charged, a reserve torque is secured through an ignition timing retard.

On the other hand, when the generator element is a motor of a hybrid vehicle, when it is determined that the battery is not required to be charged, the amount of air supplied to the engine is reduced corresponding to the reserve torque that the motor can reserve, And a second strategy for securing the second strategy.

In the second strategy, when the reserve torque that can be secured by the motor is less than the required reserve torque, the amount of air supplied to the engine is increased and the ignition timing of the engine is delayed to secure additional reserve torque It is possible.

When following the second strategy, when the required torque is generated not by the driver's will, the motor consumes the reserve torque equivalent to the required torque.

In this case, when the required torque, which is not caused by the driver's will, is generated when securing a part of the reserve torque through the ignition timing retarding of the engine in the second strategy, the required torque is firstly corresponding to the required torque through the advancement timing of the ignition timing, If the torque generated through the time advancing can not reach the required torque, then it can correspond to the required torque through the motor.

In the second strategy, after the motor consumes the reserve torque corresponding to the required torque, the amount of air supplied to the engine is increased to increase the output torque of the engine, while corresponding to the request Thereby reducing the torque.

On the other hand, when the required torque due to the driver's will is generated in the state where the necessary reserve torque is secured according to the first strategy or the second strategy, the secured reserve torque is consumed, and when the secured reserve torque is insufficient The output torque of the engine or the engine and the motor is increased.

The calculation of the required reserve torque may include a torque required for starting from the ramp, a torque required for driving the cooling fan to operate by raising the cooling water temperature, and a torque required when the air conditioner is operated.

According to the reserve torque securing method of the present invention having the above-described configuration, it is possible to quickly provide the reserve torque secured when a required torque is generated through the organic reserve torque sharing between the engine and the generator element.

Particularly, even if the reserve torque securing method of the present invention is applied to a hybrid vehicle having a small power sharing ratio, the (+) or (-) torque of the motor is reliably utilized as a reserve torque Lt; / RTI >

Furthermore, in the case of a hybrid vehicle having a small power sharing ratio of the motor, the reserve torque can be ensured while charging the battery during idling through the method of securing the reserve torque of the present invention. , For example, the torque assist of the motor can be utilized more frequently in a situation such as a start or an acceleration after a stop on a hill, thereby improving the overall driving efficiency of the hybrid vehicle.

Further, since the power generation torque of the power generating machine element is utilized as the reserve torque, the fuel consumption of the engine can be improved by organically controlling the amount of air and the ignition timing for the engine having a reduced burden.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view schematically showing a power system of a hybrid vehicle. Fig.
2 is a flowchart of a method for securing a reserve torque in a hybrid vehicle according to the present invention.
3 is a diagram schematically comparing a reserve torque securing method using a conventional ignition timing retard angle and a reserve torque securing method of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the embodiments of the present invention, a description of well-known structures that can be easily understood by those skilled in the art will be omitted so as not to obscure the gist of the present invention. In the drawings, like reference numerals refer to like elements throughout. The same elements will be denoted by the same reference numerals even though they are shown in different drawings. Referring to the drawings, The size of the elements, etc., may be exaggerated for clarity and convenience of explanation.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; coupled "or" connected "indirectly while intervening in the context of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view briefly showing a power system of a vehicle to which a reserve torque securing method according to the present invention is applied.

As shown in the figure, the output shaft 2 of the engine 1 is controlled to be connected to the transmission 4 via the clutch 3 with power. The power generating machine element 5 is directly connected to the output shaft 2 of the engine 1.

The power generation machine element 5 collectively refers to a mechanical element that converts mechanical power received from the engine 1 into electrical energy. In a general vehicle in which the engine is a single power source, the alternator corresponds to the power generation machine element 5, and in the hybrid vehicle having both the engine and the motor, the motor corresponds to the power generation machine element 5.

It should be noted that the alternator can act only as a negative torque on the output shaft 2 of the engine 1 but the motor can act as a positive or negative torque on the output torque of the engine 1 . Here, (+) torque means a torque for increasing the output torque of the engine 1, and (-) torque acts when the power generation machine element 5 generates power to charge the battery with the power generation torque.

However, since the alternator and the motor function as generators, the functions are common in that they can act on the output torque of the engine 1 as a negative torque (-). In this respect, the same strategy for securing the reserve torque is applied It is possible.

FIG. 1 also shows a cooling fan 6 for cooling the radiator as a representative type requiring a reserve torque.

On the other hand, the hybrid vehicle is provided with two power sources, that is, the engine 1 and the motor. The hybrid vehicle is classified into micro / mild / full type based on the power sharing ratio of the motor. From the micro system to the full system, the power share of the motor becomes larger. The smaller power sharing of the motor means that the output of the motor as well as the capacity of the battery is smaller.

Since the output of the motor and the capacity of the battery are relatively small, there is a limitation in securing the torque of the motor at a constant reserve torque when a torque increase request occurs. That is, when the output of the motor does not reach the required reserve torque or the battery state of charge (SOC) changes frequently, the torque of the motor may not be used as a reserve torque when necessary.

The present invention is a control logic suitable for application to micro and mild hybrid vehicles among hybrid vehicles, and provides a method for optimally maintaining reserve torque by organically utilizing engine 1 and motor.

A series of control logic for the reserve torque securing method according to the present invention is well illustrated in the flowchart of FIG.

The reserve torque securing method of the present invention will be described in detail with reference to FIG.

The first step is to determine if the vehicle is idle. The reason for reserving the reserve torque is to cope with an increase in the required torque not depending on the will of the driver when the vehicle is in the idle state. Since the idle state can be seen without the driver's intention, the idle state can be seen if the pedal is not pressed.

If it is determined that the vehicle is in the idle state, then the required reserve torque is calculated. The required reserve torque refers to the margin of the output torque that can quickly respond to sudden increases in the idle state irrespective of the driver's operation of the accelerator pedal (driver's will).

For example, if the current vehicle departs from a ramp, the torque required for driving the cooling fan, which will soon become operational due to the increase in torque and cooling water temperature, which is needed more than when starting from the ground in proportion to the gradient, Torque and so on. The items to be included in the required reserve torque and the necessary torque in each case are inputted in advance on the ECU.

When the necessary reserve torque is calculated, the charging state of the battery is determined. The present invention is characterized by the determination of the charging state and the strategy of securing the reserve torque depending on the determination.

The state of charge of the battery is divided into a state in which charging is required if the threshold value does not exceed the threshold value, and a state in which the battery can be discharged if the threshold value is exceeded. This hysteresis should be applied to avoid unnecessary repetition of charging and discharging. In addition, hysteresis may be influenced by various factors affecting battery performance such as atmospheric temperature, charging capacity of generator elements, charging efficiency of battery Life remaining) should be considered.

As a result of determining the state of charge (SOC) of the battery, if it is determined that charging is necessary, the first strategy for securing the reserve torque is followed.

The first strategy is represented by a series of flows labeled as " Method 1 " in Fig. 2, in which a generator torque (i.e., (-) torque) is applied to the generator element by the calculated required reserve torque, Advance. The final output torque of the engine is a torque that can maintain the idle state. However, instead of using the power generation torque corresponding to the required reserve torque of the generator element, the engine compensates the increased torque by the advance angle of the ignition timing to be. That is, the first strategy is to secure the required reserve torque as the power generation torque of the power generation machine element (refer to FIG. 3 (b)).

In such a state, when a situation in which torque is required to the cooling fan due to a required torque, for example, an increase in cooling water temperature, which is not caused by the driver's will occurs, the ignition timing of the engine is maintained The torque is reduced by the required torque generated to cope with the increase in the required torque.

Particularly, the above-described first strategy is characterized in that it can be applied to both the alternator in a general vehicle and the motor in a hybrid vehicle, and consumes the reserve torque secured through electrical control for reducing the generation torque, It has the advantage of being fast.

And, if the alternator is composed of a system capable of adjusting the power generation torque (i.e., a system capable of regulating the power generation load), it is also possible to appropriately change the amount of reserve torque to be secured, as in the case of the hybrid vehicle, It is possible.

The first strategy for securing the generation torque of the generator element with the reserve torque is to improve the state of charge of the battery and to secure the reserve torque and to advance the ignition timing of the engine differently from the prior art, The advantages of improving the fuel efficiency of the children of the vehicle can be obtained.

Particularly, in the case of a hybrid vehicle having a small power sharing ratio of the motor, the reserve strategy can be ensured while charging the battery during idling according to the first strategy. In a situation in which torque assist of the motor is required, For example, the torque assist of the motor can be utilized more frequently in a situation such as starting from a hill or accelerating after a stop, thereby improving the overall driving efficiency of the hybrid vehicle.

If it is determined that the state of charge of the battery (SOC) is determined to be very bad and the required torque is generated, and the consumption of the generator torque of the generator element as the reserve torque should be limited, So that the reserve torque must be secured.

If it is determined that the generator is an alternator of a general vehicle and that the state of the battery is very good as a result of determining the state of charge (SOC) of the battery, if it is determined that charging is not necessary, the ignition timing retard is used, .

On the other hand, in the case of the hybrid vehicle, when it is determined that the battery is not required to be charged, a new second strategy for securing the reserve torque can be followed.

The second strategy is represented by a series of flows labeled 'Method 2' in FIG. 2, basically utilizing the drive torque (i.e., (+) torque) of the motor since the battery is in a condition suitable for driving the motor .

That is, the second strategy is to provide an additional reserve torque to be applied to a hybrid vehicle in which the electric power generating machine element is a motor. In this way, the required reserve torque is reduced in such a manner as to reduce the amount of air supplied to the engine corresponding to the reserve torque that can be provided by the motor (See Fig. 3 (c)).

The second strategy secures the reserve torque in a range in which the motor is able to cope with, while securing the necessary reserve torque in both of the engine and the engine output torque increase that can be obtained by again increasing the reduced air amount.

In addition, since the engine consumes a small amount of air, it is possible to obtain an effect of improving the fuel efficiency of the idle engine. This is because it is not necessary to secure the reserve torque through the ignition timing retardation.

Here, according to the second strategy, if the reserve torque that can be secured by the motor is less than the required reserve torque, the amount of air supplied to the engine is increased and the ignition timing of the engine is delayed to further reserve the reserve torque do. In this case, since the output of the motor is considerably small, the ignition timing retard angle of the engine is inevitably used in combination. However, the ignition timing retard amount can be made smaller than the conventional one as long as the motor takes part of the required reserve torque. Therefore, also in this case, the fuel efficiency of the engine at idle is improved as compared with the prior art.

If the required torque is not caused by the driver's will while following the second strategy, if the ignition timing of the engine is sufficiently advanced, the motor will firstly consume the reserve torque equivalent to the required torque.

In the second strategy, it is preferable to increase the amount of air supplied to the engine to increase the output torque of the engine after the motor consumes the reserve torque corresponding to the required torque, and to reduce the required torque that the motor has burdened can do. This is because, when the demand torque suddenly increases, the motor can respond immediately, but considering that increasing the air amount of the engine is accompanied by a time delay, that is, by using a motor having a high response speed After a certain period of time, an engine having a low responsiveness is utilized. As the air amount is increased and the driving torque of the motor is reduced, a reserve torque with high responsiveness is secured again.

If a part of the required reserve torque is secured by using the ignition timing retarding angle of the engine in accordance with the second strategy, the required torque is provided through the advancement of the ignition timing together with the increase of the air amount.

Since the time corresponding to the required torque is increased through the advance of the ignition timing, the time corresponding to the required torque takes longer in comparison with the corresponding one through the advance of the ignition timing. Thus, If the generated torque does not reach the required torque, then it may be efficient to replace the torque corresponding to the motor through the increase of the air quantity of the engine after first responding via the motor.

When the required torque (required torque by manipulating the pedal) is generated by the driver's will in a state in which the required reserve torque is secured according to the first strategy and the second strategy, the first strategy and / or the second strategy And if the reserved reserve torque is consumed or becomes insufficient, control to increase the output torque of the engine and the motor (in the case of a hybrid vehicle) may be performed as in a normal running state.

The method of securing the reserve torque of the present invention is particularly suitable for a micro / mild hybrid vehicle in which the output of the motor is small and the capacity of the battery is limited. This is because the engine and the motor are utilized organically, This is because this method can be regarded as a reserve torque securing method.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. It will be possible. Accordingly, the scope of the present invention will be determined by the description of the claims and their equivalents.

1: Engine 2: Output shaft
3: clutch 4: transmission
5: Generator element 6: Cooling fan

Claims (11)

Determining whether the vehicle is idle;
Calculating a necessary reserve torque when the vehicle is in an idle state;
Determining a state of charge of the battery; And
Performing a first strategy of applying a power generation torque to the power generation machine element by the required reserve torque and advancing an ignition timing of the engine to secure the required reserve torque when it is determined that charging of the battery is necessary;
Wherein the vehicle is a vehicle. The method according to claim 1,
Wherein the generator element is a motor of an alternator or a hybrid vehicle. The method according to claim 1,
When the required torque not due to the will of the driver is generated while securing the reserve torque according to the first strategy, the ignition timing of the engine is maintained at the advancing state and the generation torque of the power generating machine element is increased by the generated required torque Wherein said control means is operable to control the amount of torque to be applied to the vehicle. The method according to claim 1,
Wherein the generator element is an alternator, and when it is determined that charging of the battery is not necessary, the reserve torque is secured through the ignition timing retard. The method according to claim 1,
Wherein the generator element is a motor of a hybrid vehicle,
And performing a second strategy of securing the required reserve torque by decreasing an amount of air supplied to the engine in correspondence with a reserve torque that the motor can reserve if it is determined that charging of the battery is not necessary Wherein the method comprises the steps of: 6. The method of claim 5,
When the reserve torque that can be secured by the motor is less than the required reserve torque in the second strategy, the amount of air supplied to the engine is increased and the ignition timing of the engine is delayed to further reserve the reserve torque To the vehicle. The method according to claim 5 or 6,
In the second strategy, when the required torque, which is not caused by the driver's will, occurs, the motor consumes a reserve torque equivalent to the required torque. The method according to claim 6,
In the second strategy, when the required torque, which is not caused by the driver's will, is generated, it corresponds to the required torque through the advancement of the ignition timing, and if the torque generated through the advancement of the ignition timing does not reach the required torque, To the required torque through the second clutch. 9. The method of claim 8,
In the second strategy, the amount of air supplied to the engine is increased to increase the output torque of the engine after the motor consumes the reserve torque corresponding to the required torque, while corresponding to the required torque Wherein said control means is operable to control the amount of torque to be applied to the vehicle. 6. The method according to claim 1 or 5,
When the required torque due to the driver's will is generated in a state in which the required reserve torque is secured, the reserved reserve torque is consumed, and when the reserved torque is insufficient, the output torque of the engine or the engine Wherein the step of increasing the reserve torque of the vehicle is carried out. 6. The method according to claim 1 or 5,
The calculation of the necessary reserve torque includes at least one or more of the required torque selected from the torque required when starting from the ramp and the torque required when the cooling fan is driven by the rise of the cooling water temperature and when the air conditioner is operated Wherein the method comprises the steps of:

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