JP2004183519A - Engine stop control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable stop of an engine even after a vehicle is stopped after pumping operation of a brake, and restrain fuel consumption. <P>SOLUTION: This engine stop control device comprises: a shift position detecting means for detecting a shift position of an automatic transmission; and an engine control means which stops the engine when a shift position is in a traveling range and an engine stop condition including detection of a brake operation is satisfied. After engine starting and when a vehicle speed is more than a predetermined value, the stop of the engine by the engine control means is permitted. After starting of the engine, when the vehicle speed is less than the predetermined value and the pumping operation of the brake is detected, the stop of the engine by the engine control means is permitted. After starting of the engine, when the vehicle speed is less than the predetermined value and the pumping operation of the brake is not detected, the stopping of the engine by the engine control means is prohibited. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an engine stop control device for an automobile, and more particularly to an engine stop control device that includes an engine and an automatic transmission and stops the engine when a predetermined idle stop condition is satisfied.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Application Laid-Open No. H11-257121 Conventionally, a control method called automatic idle stop control for automatically stopping an engine when stopping from a running state and suppressing wasteful consumption of fuel and generation of exhaust gas while the vehicle is stopped. Cars that implement the following have been proposed.
In such an automobile, conditions for permitting automatic stop of the engine include a shift position being a neutral position such as N or P, a brake being ON, and the like. Conditions) include switching from a neutral position to a travel position such as D or R, brake being off, depression of an accelerator pedal, and the like. Also, in the case of an automobile equipped with an automatic transmission with a torque converter, the torque converter allows relative rotation between the engine and the automatic transmission, so that the engine is automatically stopped not only at the neutral position but also at the traveling position. It becomes possible.
[0003]
By the way, in the case where the stop and start of the vehicle are repeated at short time intervals on a congested road, the stop and restart of the engine are frequently repeated, which is disadvantageous for the driver.
To solve this problem, Patent Literature 1 proposes an engine stop control device that prevents the engine from being frequently stopped and restarted during a traffic jam or the like. This engine stop control device stops the engine when the automatic transmission is in a non-traveling position or a traveling position and a brake operation is performed after reaching a predetermined vehicle speed. After the engine is started, stop of the engine is prohibited until the vehicle speed first exceeds a predetermined value. Therefore, in a case where the stop and start of the vehicle are repeated, such as during a traffic jam, the driving state of the engine is maintained, and it is possible to prevent the engine from being repeatedly stopped and restarted.
[0004]
[Problems to be solved by the invention]
However, if the brake is pumped during deceleration of the vehicle, the following problems occur. That is, the pumping operation is to depress the brake pedal again. However, when the control of Patent Document 1 is performed, if the pumping operation is performed during deceleration, the engine may be stopped unless the vehicle speed once rises to a predetermined value. If the vehicle is stopped after the pumping operation, fuel consumption cannot be suppressed.
[0005]
FIG. 5 shows a change in vehicle speed when the vehicle stops after a pumping operation, a braking operation, and an engine control according to Patent Document 1.
When the brake is turned on at time t1, a deceleration fuel cut is performed, and the vehicle speed decreases. Eventually, even if the engine speed drops below the idle speed at time t2, the fuel supply is stopped, so that an idle stop is performed. When the brake is turned off at time t3, the idle stop is released and the engine is started. However, even if the brake is turned on again at time t4 immediately after that, since the vehicle speed has not increased to the predetermined value, the fuel injection of the engine is continued. Therefore, even after the vehicle stops at time t5, the engine remains driven.
[0006]
SUMMARY OF THE INVENTION It is an object of the present invention to provide an engine stop control device for an automobile, which can stop an engine even after the vehicle stops after a brake pumping operation and can suppress fuel consumption.
[0007]
[Means for Solving the Problems]
To achieve the above object, an invention according to claim 1 includes an engine, an automatic transmission that transmits a driving force of the engine to driving wheels, a shift position detection unit that detects a shift position of the automatic transmission, and a driver. Brake operation detecting means for detecting the brake operation of the vehicle, vehicle speed detecting means for detecting the vehicle speed, and stopping the engine when the shift position is in the travel range and a predetermined engine stop condition including the detection of the brake operation is satisfied. An engine stop control device for an automobile, comprising: a pumping operation detecting unit configured to detect a pumping operation of the brake. After the engine is started, the vehicle speed detected by the vehicle speed detecting unit becomes equal to or higher than a predetermined value. Stop the engine by the engine control means, and after the engine starts, the vehicle speed detection means When the detected vehicle speed is less than a predetermined value and the pumping operation detecting means detects the pumping operation of the brake, the engine control means is permitted to stop the engine, and after the engine is started, the vehicle speed is detected by the vehicle speed detecting means. When the vehicle speed is lower than a predetermined value and the pumping operation detecting means does not detect the pumping operation of the brake, the engine stop control of the engine is prohibited by the engine control means.
[0008]
In the present invention, three types of engine control are performed when the vehicle stops from the running state. The first is when the vehicle speed detected by the vehicle speed detecting means has at least once reached a predetermined value or more after the engine is started. At this time, the stop of the engine by the engine control means is permitted. That is, if other engine stop conditions are satisfied, the engine can be stopped and fuel consumption can be reduced.
The second is a case in which the vehicle speed detected by the vehicle speed detecting means has never reached the predetermined value after the engine is started, and the pumping operation detecting means detects the pumping operation of the brake. Allow the engine to stop. That is, when the vehicle is stopped after the brake is pumped during deceleration, the engine can be stopped. Therefore, the engine can be stopped even during the stop and fuel consumption can be reduced.
Third, when the vehicle speed detected by the vehicle speed detecting means has never reached the predetermined value after the engine is started, and the pumping operation detecting means does not detect the pumping operation of the brake. Prohibit the engine from stopping due to That is, when the vehicle is stopped without performing the pumping operation of the brake, the stop of the engine is prohibited until the vehicle speed becomes equal to or higher than the predetermined value as before, so that it is possible to prevent the engine from being repeatedly stopped and restarted during a traffic jam. .
[0009]
As described in claim 2, the pumping operation detecting means determines that there is no accelerator operation during the brake OFF period from the previous brake ON to the current brake ON, or the brake OFF time from the previous brake ON to the current brake ON. Is within a predetermined time, it is preferable to detect a brake pumping operation.
In this case, even if the number of times of stepping on the brake is large, the pumping operation of the brake can be reliably detected. In addition, since the pumping operation can be detected programmatically using the brake operation signal of the brake operation detecting means, no special sensor is required.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a system configuration of a hybrid vehicle which is an example of a vehicle provided with an engine stop control device according to the present invention.
A motor generator 7 is provided between an output shaft of the engine 1 and an input shaft of the automatic transmission 2, and an output shaft 5 of the automatic transmission 2 is connected to driving wheels (not shown). The automatic transmission 2 of this example is a stepped automatic transmission including a torque converter 3, a transmission mechanism 4 having a plurality of frictional engagement elements, and a hydraulic control device 6.
[0011]
The engine 1 is controlled by an engine control controller 20, the automatic transmission 2 is controlled by an AT control controller 21, and the motor generator 7 is controlled by a motor control controller 22. Signals are input to the controllers 20, 21, 22 from various sensors, and are connected to each other via a communication bus 23. The input signals include a vehicle speed signal, a throttle opening (accelerator opening) signal, a shift position signal, an air conditioner signal, an ignition signal, an idle signal, an engine water temperature signal, an intake air amount signal, an engine speed signal, a turbine speed signal, There are a start signal, a brake signal, a battery capacity, and the like. The brake signal is obtained, for example, from a brake switch that detects depression of a brake pedal.
[0012]
When a predetermined engine stop condition is satisfied, the engine control controller 20 automatically stops the engine 1 and performs idle stop control (engine stop control) to suppress wasteful fuel consumption and emission of gas while the vehicle is stopped. Further, based on the engine speed and the throttle opening, deceleration fuel cut control for suppressing unnecessary fuel consumption during traveling is performed.
The engine stop conditions include that the shift position is P, that the shift position is N or D, and that the brake is ON. However, when the engine water temperature is low, the battery capacity is low, the electric load is large, the accelerator pedal is depressed, and the like, the automatic stop is not permitted.
On the other hand, as the restart condition (stop release condition) of the engine 1, the brake was turned off, the shift position was shifted to the R or L position, the accelerator pedal was depressed, and a vehicle speed signal was input. There are things.
The engine control controller 20 also has a function of detecting a brake pumping operation. In this pumping operation, there is no accelerator operation during the brake OFF period from the previous brake ON to the current brake ON, or the brake OFF time Δt from the previous brake ON to the current brake ON is within a predetermined time. Can be detected.
[0013]
As is well known, the AT control controller 21 determines the shift speed according to a shift map set in advance according to the running state, and controls the solenoid valves 24-26 incorporated in the hydraulic control device 6 to thereby control the frictional engagement. The hydraulic pressure is selectively supplied to the combined element to shift to the determined gear. In this embodiment, three solenoid valves 24 to 26 for shifting control are provided in the hydraulic control device 6, but other solenoid valves for lock-up clutch control, line pressure control, and the like may be provided. .
[0014]
The battery 8 is connected to the motor control controller 22 to drive the motor generator 7 at appropriate times to start and assist the engine 1 and to store the regenerative energy of the motor generator 7 in the battery 8.
[0015]
2 and 3 show time charts using the engine stop control method according to the present invention. These time charts show a change in vehicle speed, a brake operation, and engine control when the vehicle is stopped after a brake pumping operation is performed from a vehicle deceleration state.
In FIG. 2, when the brake is turned on at time t1, deceleration fuel cut is performed, and the vehicle speed decreases. Eventually, even if the engine speed drops below the idle speed at time t2, the fuel supply is stopped, so that an idle stop is performed. When the brake is turned off at time t3, the idle stop is released and the engine is started. The above operation is the same as in the conventional example (see FIG. 5).
When the brake is turned on again at time t4 immediately after time t3, it is determined that the operation is a pumping operation because the brake OFF time Δt is shorter than a predetermined time. When the pumping operation is determined, the stop of the engine is permitted. At this time, if a predetermined engine stop condition is satisfied, a fuel cut is performed and the engine is stopped. Therefore, even after the vehicle stops at time t5, the engine is stopped, and fuel consumption can be reduced.
[0016]
FIG. 3 shows the control after the vehicle is stopped in FIG. 2, and particularly shows the engine control during a traffic jam.
After the vehicle stops at time t5, the brake is turned off at time t6 and the accelerator pedal is depressed, so that the engine is restarted and the vehicle can start. However, if the brake is turned on again at time t7 before the vehicle speed increases to the predetermined vehicle speed Vo, the engine should normally be stopped. In this case, the stop and restart of the engine are frequently repeated in a traffic jam or the like. Results. Therefore, when the vehicle stops without increasing to the predetermined vehicle speed Vo, the engine stop is prohibited. Therefore, the engine is not stopped regardless of whether other engine stop conditions are satisfied.
The predetermined vehicle speed Vo is a vehicle speed for determining whether or not there is a traffic jam, and is set to, for example, about 10 to 15 km / h.
[0017]
In the present invention, the pumping operation of the brake is determined by comparing the brake OFF time Δt with a predetermined time. The predetermined time for this determination is as short as about 1 to 2 seconds, which is much shorter than the brake OFF time during a traffic jam or the like, so that a brake operation during a traffic jam is not erroneously determined as a pumping operation.
In order to determine the pumping operation, instead of comparing the brake OFF time Δt with a predetermined time, the determination may be made based on the absence of an accelerator operation during the brake OFF period. That is, the pumping operation is an operation performed for deceleration, and if there is an accelerator operation in the middle, it is determined that there is an intention to accelerate, and it can be distinguished from the pumping operation. Further, the pumping operation may be determined based on both the condition that the brake OFF time Δt is compared with the predetermined time and the condition that the accelerator operation is not performed during the brake OFF period. In this case, the pumping operation can be determined more reliably.
[0018]
FIG. 4 is a flowchart illustrating an example in which idle stop control is performed during traveling in the D range.
When the control starts, it is determined whether an engine stop condition is satisfied (step S1). The engine stop conditions include, for example, that the shift position is in the D range, that the brake is ON, that the battery capacity is sufficient, and the like. If the engine stop condition is not satisfied, fuel injection is continued (step S2). If it is determined in step S1 that the engine stop condition is satisfied, it is determined whether or not the vehicle speed has exceeded a predetermined value Vo (vehicle speed history) after starting the engine (step S3). The predetermined value Vo is a vehicle speed serving as a reference for determining whether or not there is a traffic jam. If the vehicle speed once exceeds the predetermined value Vo after the engine is started, a fuel cut is performed (step S4). On the other hand, if the vehicle speed has never exceeded the predetermined value Vo after the engine is started, it is determined whether or not the brake has been pumped (pumping operation history) (step S5). If there is a history of the pumping operation, a fuel cut is performed (step S4), and the engine is stopped. If there is no history of the pumping operation, the fuel injection is continued (step S2), and the engine is continuously driven. Therefore, it is possible to eliminate a situation in which the stop and restart of the engine are frequently repeated during a traffic jam or the like.
[0019]
The present invention is not limited to the above embodiment.
In the above embodiment, the brake ON or OFF is detected using the brake switch. However, the brake operation may be detected as brake ON when the brake fluid pressure is equal to or higher than the threshold and brake OFF when the brake fluid pressure is less than the threshold. .
In the above embodiment, a hybrid vehicle including a motor generator in addition to the engine and the automatic transmission has been described. However, the present invention can be applied to a general AT vehicle including an engine and an automatic transmission.
The automatic transmission according to the present invention includes a continuously variable transmission such as a V-belt type or a toroidal type, in addition to a stepped transmission having a planetary gear device and a friction engagement element.
[0020]
【The invention's effect】
As is apparent from the above description, according to the first aspect of the invention, the permission or prohibition of the engine stop is determined based on the presence or absence of the pumping operation of the brake. The engine can be stopped even after the vehicle stops after the pumping operation, and the fuel consumption can be suppressed.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a hybrid vehicle which is an example of a vehicle including an engine stop control device according to the present invention.
FIG. 2 is a time chart illustrating an example of engine stop control according to the present invention.
FIG. 3 is a time chart illustrating an example of engine stop control continued from FIG. 2;
FIG. 4 is a flowchart illustrating an example of engine stop control according to the present invention.
FIG. 5 is a time chart showing an example of a conventional engine stop control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Automatic transmission 3 Torque converter 7 Motor generator 20 Engine control controller 21 Motor control controller 22 AT control controller

Claims (2)

Engine and
An automatic transmission that transmits the driving force of the engine to the driving wheels;
Shift position detecting means for detecting a shift position of the automatic transmission;
Brake operation detecting means for detecting a driver's brake operation;
Vehicle speed detecting means for detecting a vehicle speed;
An engine control means for stopping the engine when the shift position is in the travel range and a predetermined engine stop condition including detection of a brake operation is satisfied.
Pumping operation detecting means for detecting the pumping operation of the brake is provided,
After the engine is started, when the vehicle speed detected by the vehicle speed detecting means is equal to or higher than a predetermined value, stop of the engine by the engine control means is permitted,
After starting the engine, when the vehicle speed detected by the vehicle speed detecting means is less than a predetermined value, and the pumping operation detecting means detects the pumping operation of the brake, the engine control means is permitted to stop the engine,
After the engine is started, when the vehicle speed detected by the vehicle speed detecting means is less than a predetermined value and the pumping operation detecting means does not detect the pumping operation of the brake, the stopping of the engine by the engine control means is prohibited. Engine stop control device for a car. The pumping operation detecting means determines that there is no accelerator operation during the brake OFF period from the previous brake ON to the current brake ON, or the brake OFF time from the previous brake ON to the current brake ON is within a predetermined time. 2. The engine stop control device for an automobile according to claim 1, wherein the pumping operation of the brake is detected.

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