KR20180067342A - Neutral control method for coasting drive - Google Patents

Abstract

The present invention relates to a method to control neutral in coasting, capable of providing quick response to a speed change and reacceleration performance. According to the present invention, the method to control neutral in coasting comprises: a first step of performing coasting neutral control automatically changing a gear stage from a driving mode (D) to a neutral mode (N) when a driver takes off a foot from an acceleration or brake pedal while a vehicle speed is equal to or higher than a predetermined speed, wherein hydraulic pressure of one solenoid valve (App. S/V) controlled in common at a predetermined gear stage or higher is fixed, only hydraulic pressure of the remaining one solenoid valve (Rel. S/V) is controlled, pre-fill hydraulic pressure control is performed in the solenoid valve (Rel. S/V) to adjust the hydraulic pressure during coasting neutral control, and an engine is changed into an idle state; a second step of determining a target gear stage suitable for an operation state at the moment and an acceleration intention of a user when a release condition is generated during a coasting neutral control state, and transferring a request to limit an engine revolutions per minute (RPM) or torque to the engine; a fourth step of transferring an engine RPM or torque value increase request fit to the target gear stage in order to maintain a pre-fill hydraulic pressure and allow the engine to synchronize the engine RPM to a transmission input speed; and a fifth step of issuing a corresponding solenoid valve command (corresponding transmission App. S/V) of the target gear stage to complete coupling of a gear stage when the engine RPM reaches the transmission input speed.

Description

[0001] The present invention relates to a neutral control method for coasting drive,

More particularly, the present invention relates to a neutral control method at the time of driving a vehicle, and more particularly, it is possible to prevent a shift shock and noise generated in a neutral mode and a traveling mode transition process, The present invention relates to a neutral control method at the time of driving a horsepower so as to reduce discomfort caused by frequent neutral control by allowing the driver to have a quick shift response and reacceleration performance.

Switching to Neutral mode (N) during driving or stopping can greatly reduce fuel consumption. For example, if the driver operates the shift lever appropriately in the high-speed travel (engine speed 2000RPM or more) to switch to the neutral mode and drops the engine speed to the idle state (about 800RPM), the fuel economy reduction effect can be expected.

Particularly, when the neutral mode is used during driving such as a downhill road, a fuel cut-off effect which is generally performed in engine control, that is, a state in which fuel is not temporarily injected into the engine cylinder, is obtained .

2. Description of the Related Art In recent years, there has been introduced a technique for improving the convenience of the driver by allowing the neutral control to be performed only by pedal operation in addition to the neutral mode switching by operating the direct shift lever of the driver.

This is because the electronic shift lever technology has been developed to enable neutral control without operating the driver's direct shift lever. The electronic shift lever is also referred to as SBW (Shift By Wire), which means that the automatic transmission and the shift lever do not interfere with mechanical elements such as wires, , Neutral, running, etc.) is transmitted / received to / from the transmission controller by electronic communication. Since there is no vibration of the shift lever, and there is an advantage that the shift operation can be performed only with small operation force and copper line.

The electronic shift lever can control the gear position of the automatic transmission differently from the position of the shift lever because the automatic transmission and the shift lever are not mechanically connected. That is, even if the position of the shift lever is set to the running end (D), the automatic transmission can be controlled to the neutral stage (N) state. It becomes possible to switch backward.

However, when switching from the driving mode to the neutral mode only by the operation of the excel pedal or vice versa, the switching between the fast and frequent neutral mode and the traveling mode causes the occasional serious load to the vehicle or a great discomfort to the driver . For example, when suddenly switching from the neutral mode to the driving mode in the driving state of the vehicle, a strong engine brake may be generated, resulting in a sudden impact and noise in the vehicle.

Therefore, in order to prevent this, proper shift control is required when entering or releasing the neutral control by pedal operation, and in particular, special consideration is required to reduce shift response and reacceleration delay feeling.

Korean Patent Publication No. 10-2016-0071011 (published on June 21, 2016)

The present invention can prevent a shift shock and noise generated during a frequently occurring neutral mode and a traveling mode transition process due to the ability to travel by a pedal operation of a driver only, And to provide a neutral control method.

The neutral control method at the time of driving the vehicle according to the present invention automatically shifts the gear from the driving mode (D) to the neutral mode (N) when the vehicle speed is at least the specific vehicle speed and the driver releases the accelerator pedal or the brake pedal The hydraulic pressure of one solenoid valve (App. S / V) which is commonly controlled at a certain gear position or higher is fixed while the hydraulic pressure control of the other solenoid valve (Rel. S / V) (S / V) for controlling the hydraulic pressure in the third neutral control, and changing the engine to an idle state, and a step A second step of maintaining the third-gear neutral control state before the occurrence of the third-gear neutral control state, A third step of transmitting a request for limiting the engine speed or torque to the engine while determining the engine speed and the torque of the engine, A fourth step of transmitting an appropriate engine speed or torque value increase request; And a fifth step of commanding the corresponding solenoid valve (corresponding shift App. S / V) of the target gear stage to complete gear engagement when the engine speed reaches the transmission input speed.

In the first step, the transient state (XN) is set for a predetermined period of time before entering the neutral state (N), and the slope of the hydraulic descent at the initial stage of the transient state A dynamic state composed of two sections G1 and G2 having a small slope G2 and a slope G2 after a predetermined time T1 may be included.

In the second step, the gear stage maintains the neutral state (N) and the engine maintains the idle state, and the hydraulic pressure of one solenoid valve (App. S / V) And the hydraulic pressure of the other solenoid valve (Rel. S / V) can maintain the pre-press hydraulic pressure.

In the third step, when the amount of the accelerator pedal and the amount of change thereof exceed the preset reference value, the target gear stage is determined to be lower than the gear stage immediately before the start of the third-wheel neutral control.

When the acceleration and the vehicle speed of the driver are changed during the shifting process being performed through the fourth and fifth steps, a new target shift stage is determined and shifting is performed accordingly.

On the other hand, if the driver's intention of acceleration occurs during the transition state XN, the neutral control is canceled and the shift is performed to the target shift stage corresponding to the driver's acceleration.

Here, the shift to the target speed change stage corresponding to the driver's acceleration will be performed by controlling the hydraulic pressure according to the slope obtained by dividing the difference between the current hydraulic pressure and the target pressure by a predetermined time.

According to the present invention having the above-described configuration, it is possible to prevent a shift shock and noise generated during a frequently occurring neutral mode and a traveling mode transition process, Thereby enabling the driver to reduce discomfort caused by frequent neutral control, and to utilize the driving force of the vehicle with high efficiency, thereby maximizing the fuel efficiency improvement effect.

FIG. 1 is a flowchart of a neutral control method in the case of a driving force according to the present invention. FIG.
Fig. 2 is a view showing, in chronological order, the states of various control elements when performing the neutral control method at the time of driving the vehicle according to the present invention; Fig.

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.

FIG. 1 is a flow chart of a neutral control method at the time of driving the vehicle according to the present invention. FIG. 2 is a view showing a state of various control elements in time order when performing the neutral control method at the time of driving the vehicle according to the present invention. The present invention will be described in detail.

1 and 2 are considered together to help the understanding of the present invention, and the numbers [1] to [5] in each step shown in the flowchart of FIG. 1 correspond to the numbers .

In FIG. 2, the control state [0] indicates a state in which neutral control is not performed in the other line (batting driving).

As shown in FIG. 2, in the present invention, the gear position is automatically switched between the traveling mode (D) and the neutral mode (N) by only pedal operation while the shift lever is maintained in the traveling mode (D) Technology. Therefore, in Fig. 2, the shift lever is indicated as being in the continuous traveling mode (D).

In order to enter the driving state, the gear position should be automatically switched from the traveling mode (D) to the neutral mode (N). The determination is made such that the vehicle speed is not less than a specific vehicle speed, If the pedal is released from the pedal, it is judged that the condition for entering the driving state is satisfied, and the control for neutral control is started.

Defines the transient state (XN) to go to neutral (N) when changing the gear stage due to third-line neutral control entry and performs appropriate hydraulic control in the corresponding period (control state [1]).

In the case of neutral control, it is necessary to neutralize the transmission gear and fasten the gear by fast operation of the pedal only by operating the pedal, unlike the neutral by the operation of the shift lever of the driver. Therefore, Pre-Fill hydraulic control is performed in which a certain level of hydraulic pressure is pre-applied to the solenoid valve for combination of valve control and quick gear engagement.

In other words, while the hydraulic pressure of one solenoid valve (App / S / V) commonly controlled at a certain gear range or higher is fixed and only the hydraulic control of the other solenoid valve Rel / S / V is performed, The solenoid valve (Rel. S / V), which controls the hydraulic pressure during control, is capable of quickly neutralizing and tightening the gears of the transmission by performing pre-hydraulic control.

Further, in the third-line neutral control, instead of entering the neutral state N immediately, the transient state XN is set for a predetermined period. This is to allow the gear engagement to be established quickly in the event that the driver's acceleration will be generated at the beginning of the third-wheel neutral control, by allowing the control hydraulic pressure to be in the transient state (XN) for a certain time before reaching the complete neutral third state.

The transient state XN may be composed of the dynamic states G1 and G2 and the static state (pre-fill hydraulic pressure). In the dynamic state, the slope of the hydraulic pressure drop is relatively small at first (G1) (G2), the slope of which is larger than the slope G2.

On the other hand, when the control enters the third-line neutral control, the control is also performed for the engine. That is, it causes the engine controller (EMS) to perform the torque control so that the engine changes to the idle state, and eventually the transient state XN ends when the engine reaches the idle state completely.

As described above, the transient state (XN) is set for a certain period of time instead of entering the neutral state (N) immediately during the third-in-first-out neutral control. This is because, if the driver's will is accelerated at the beginning of the third- So that engagement of the gears is achieved.

That is, when the third-row neutral control start condition occurs and the third-row neutral control is entered and the driver's acceleration is generated during the transient state (XN) progresses (when the accelerator pedal is pressed again) Accordingly, the hydraulic pressure control corresponding to the driver's acceleration will be performed.

If the driver's acceleration will be generated during the transient state XN, the transient state can be quickly obtained by using the slope (target pressure-current pressure / settling time) obtained by dividing the difference between the current hydraulic pressure and the target pressure by a preset time (XN). Here, the target pressure means an oil pressure corresponding to the target speed change stage according to the driver's acceleration will, and the preset time is a preset time for alleviating the shock due to the rise of the oil pressure.

When the hydraulic pressure reaches the target pressure within the set time, the target gear engagement is immediately performed without going through the neutral state N, so that the driver's acceleration will be reflected as quickly as possible.

On the other hand, when the third-line neutral control continues and the transient state XN ends, the third neutral control state is maintained (control state [2]) until the cancellation condition of the driving force (costing) occurs.

In the neutral control mode, the gear stage maintains the neutral state (N) and the engine maintains the idle state, and the hydraulic pressure of the transmission is controlled to be the same as the hydraulic pressure of one solenoid valve (App. And the hydraulic pressure of the other solenoid valve (Rel. S / V) maintains the pre-press hydraulic pressure for fast gear engagement.

If the release condition occurs in the neutral control state, the neutral command is canceled and the gear stage is started to be engaged at the appropriate gear stage according to the operation state and the user's acceleration will be started (control state [3]).

In this case, in the transmission, a delay time (T1 delay) is required to determine the target gear stage suitable for the operating state and the user's acceleration will. During this time, the excessive gearing of the driver due to the sudden acceleration pedal operation A request to limit the engine speed or torque is transmitted to the engine controller during a certain period or state to prevent the engine speed from rising.

For example, if the driver's acceleration is weak and the vehicle speed is not substantially different from that before the third-wheel-neutral control, the target gear stage is determined by considering the driver's acceleration (the amount of the accelerator pedal and the amount of change) 2) can be set as the target gear stage. If the driver has a strong will to accelerate, the lower stage (5 stages in FIG. 2) can be set as the target gear stage to improve the quick acceleration response.

(T2 delay) after the delay time (T1 delay) for determining the target gear range, while the engine controller is operated with the engine that has fallen to the idle level to prevent the shift shock due to excessive engine braking, The engine speed or the torque value increase request corresponding to the present target gear stage is transmitted (control state [4]) so that the rotation speed reaches the transmission input speed and is synchronized with each other. At this time, the target turbine speed value calculated through the current vehicle speed and the target gear stage is directly sent, or the torque increase value according to the difference between the current engine speed and the turbine speed is transmitted to the engine controller, .

Then, when the engine speed reaches the transmission input speed, a command is issued to the corresponding solenoid valve (corresponding shift App. S / V) of the target gear stage to complete gear engagement (control state [5]).

At this time, since the accelerator and the vehicle speed of the driver may be different during the execution of the first-determined shift control, it is necessary to allow the new shift to be immediately allowed even during the current shift.

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.

Claims (7)

Neutral control in which the gear position is automatically switched from the traveling mode (D) to the neutral mode (N) when the vehicle speed is not lower than a specific vehicle speed and the driver releases the accelerator pedal or the brake pedal, The hydraulic pressure of one solenoid valve (App / S / V), which is controlled in common, is fixed and the hydraulic pressure of the other solenoid valve (Rel / S / V) is controlled while the hydraulic pressure is controlled The solenoid valve (Rel. S / V) is subjected to pre-hydraulic pressure control, and the engine is changed into an idle state.
A second step of maintaining the third-line neutral control state until a disengagement condition of the second-speed driving occurs;
A third step of, when a release condition occurs in the third neutral control state, determining a target gear stage that matches the current state of operation and the acceleration of the user, and transmitting a request to the engine to limit the engine speed or torque;
A fourth step of transmitting an engine speed or a torque value increase request corresponding to the target gear stage so that the engine speed is synchronized with the transmission input speed while maintaining the pre-piled hydraulic pressure; And
When the engine speed reaches the transmission input speed, a command is issued to the corresponding solenoid valve (corresponding shift App. S / V) of the target gear stage to complete gear tightening;
Wherein the neutral control method comprises the steps of: The method according to claim 1,
In the first step, the transient state (XN) is set for a certain period of time before entering the neutral state (N), and the slope of the hydraulic descent is relatively small at the beginning of the transient state (XN) (G1) a dynamic state composed of two sections (G1, G2) having a larger slope (G2) after a predetermined time (T1). The method according to claim 1,
In the second step, the gear stage maintains the neutral state (N) and the engine maintains the idle state, and the hydraulic pressure of the one commonly controlled solenoid valve (App. S / V) And the hydraulic pressure of the other solenoid valve (Rel. S / V) maintains the pre-press hydraulic pressure. The method according to claim 1,
Wherein when the amount of the accelerator pedal and the amount of change of the accelerator pedal exceed the preset reference value, the target gear stage is determined to be lower than the gear stage immediately before the start of the third-wheel neutral control. Way. The method according to claim 1,
Wherein when the driver's acceleration and the vehicle speed are changed during the shifting process being performed through the fourth and fifth steps, a new target shift stage is determined and shifting is performed according to the determined target shift stage. . 3. The method of claim 2,
Wherein when the driver's acceleration is to be generated during the transition of the transient state (XN), the third-line neutral control is canceled and the shifting to the target speed change stage corresponding to the driver's acceleration is performed. The method according to claim 6,
Wherein the shifting to the target speed change stage corresponding to the driver's acceleration is performed by controlling the hydraulic pressure according to a slope obtained by dividing the difference between the current hydraulic pressure and the target pressure by a predetermined time.

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