JP4112351B2 - Automotive engine stop control device - Google Patents

Description

[0001]
BACKGROUND 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]
JP, 11-257121, A Conventionally, an automobile that performs a control method called automatic idle stop control that automatically stops an engine when stopping from a running state and suppresses wasteful fuel consumption and generation of exhaust gas while the vehicle is stopped. Proposed.
In such automobiles, the conditions for permitting automatic engine stop include that the shift position is a neutral position such as N or P, the brake is ON, and the like. (Conditions) include switching from the neutral position to a travel position such as D, R, the brake being OFF, and the accelerator pedal being depressed. 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, when the stop and start of the vehicle are repeated at a short time interval on a congested road, the engine is frequently stopped and restarted, which is annoying for the driver.
In order to solve this problem, Patent Document 1 proposes an engine stop control device that prevents frequent stop and restart of the engine during a traffic jam or the like. This engine stop control device stops the engine when the automatic transmission is in a non-travel position or a travel position and a brake operation is performed after reaching a predetermined vehicle speed. Then, after the engine is started, engine stop is prohibited until the vehicle speed first exceeds a predetermined value. Therefore, when the stop and start of the vehicle are repeated as in a traffic jam, it is possible to maintain the driving state of the engine and prevent frequent stop and restart of the engine.
[0004]
[Problems to be solved by the invention]
However, if the brake is pumped when the vehicle is decelerated, the following problems occur. That is, the pumping operation is to depress the brake pedal. 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 stops after the pumping operation, fuel consumption cannot be suppressed.
[0005]
FIG. 5 shows changes in vehicle speed when the vehicle stops after the pumping operation, brake operation, and engine control according to Patent Document 1.
When the brake is turned on at time t1, deceleration fuel cut is performed and the vehicle speed decreases. Since the fuel supply is stopped even if the engine speed drops below the idle speed at time t2, the 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, the vehicle speed has not increased to the predetermined value, and therefore the fuel injection of the engine is continued. Therefore, the engine remains driven even after the vehicle stops at time t5.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide an automobile engine stop control device that can stop an engine even after stopping after a pumping operation of a brake and can suppress fuel consumption.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is directed to an engine, an automatic transmission that transmits the driving force of the engine to drive wheels, a shift position detection means that detects a shift position of the automatic transmission, and a driver. A brake operation detecting means for detecting the brake operation of the vehicle, a vehicle speed detecting means for detecting the vehicle speed, and when a predetermined engine stop condition including when the shift position is in the traveling range and the brake is decelerated is satisfied . allow stop in automobile engine stop control apparatus having engine control means for Ru the engine is restarted, the when the brake OFF, provided a pumping operation detecting means for detecting a pumping operation of the brake, after starting the engine, When the vehicle speed detected by the vehicle speed detection means exceeds a predetermined value, the engine by the engine control means Permits stopping, and 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 detects a pumping operation of the brake, the engine control means permits the engine to stop. 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 engine control means prohibits the engine from being stopped. An automobile engine stop control device is provided.
[0008]
In the present invention, three kinds 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 once exceeds the predetermined value after the engine is started. At this time, the engine control means permits the engine to be stopped. That is, if other engine stop conditions are satisfied, the engine can be stopped and fuel consumption can be reduced.
Second, after the engine is started, the vehicle speed detected by the vehicle speed detecting means never reaches a predetermined value, and the pumping operation detecting means detects the pumping operation of the brake. At this time, the engine control means Allow the engine to stop. That is, the engine can be stopped when the vehicle is stopped after the brake is pumped during deceleration, so that the engine can be stopped even when the vehicle is stopped, and fuel consumption can be reduced.
Third, after the engine is started, the vehicle speed detected by the vehicle speed detecting means never reaches the predetermined value, and the pumping operation detecting means does not detect the pumping operation of the brake. At this time, the engine control means The engine stop by is prohibited. In other words, when the vehicle stops without pumping, the engine is prohibited from stopping until the vehicle speed reaches a predetermined value as before, so that frequent stopping and restarting of the engine in a traffic jam can be prevented. .
[0009]
As described in claim 2, the pumping operation detection means detects 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 the pumping operation of the brake.
In this case, it is possible to reliably detect the pumping operation of the brake even if the number of times of brake switching is large. Further, 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]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a system configuration of a hybrid vehicle which is an example of a vehicle including an engine stop control device according to the present invention.
A motor generator 7 is provided between the output shaft of the engine 1 and the input shaft of the automatic transmission 2, and the output shaft 5 of the automatic transmission 2 is connected to drive wheels (not shown). The automatic transmission 2 in this example is a stepped automatic transmission that includes a torque converter 3, a transmission mechanism 4 having a plurality of friction 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 from various sensors are input to the controllers 20, 21, and 22, and are connected to each other via a communication bus 23. Input signals include vehicle speed signal, throttle opening (accelerator opening) signal, shift position signal, air conditioner signal, ignition signal, idle signal, engine water temperature signal, intake air amount signal, engine speed signal, turbine speed signal, There are start signal, brake signal, battery capacity and so on. The brake signal is obtained from, for example, a brake switch that detects depression of the brake pedal.
[0012]
The engine control controller 20 performs idle stop control (engine stop control) that automatically stops the engine 1 when a predetermined engine stop condition is satisfied, and suppresses wasteful fuel consumption and emission of exhaust gas while the vehicle is stopped. Further, deceleration fuel cut control for suppressing wasteful fuel consumption during traveling is performed based on the engine speed and the throttle opening.
As engine stop conditions, the shift position is P, the shift position is the N or D position, and the brake is ON. However, automatic stop is not permitted when the engine water temperature is low, the battery capacity is low, the electric load is large, or the accelerator pedal is depressed.
On the other hand, the restart condition (stop release condition) of the engine 1 was that the brake was turned off, the shift position was shifted to the R or L position, the accelerator pedal was stepped on, and a vehicle speed signal was input. There are things.
The engine control controller 20 also has a function of detecting a pumping operation of the brake. 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 a gear position according to a shift map set in advance according to the running state, and controls the solenoid valves 24 to 26 built in the hydraulic control device 6 to thereby adjust the frictional force. The hydraulic pressure is selectively supplied to the coupling element, and the gear is shifted to the determined gear position. In this embodiment, the hydraulic control device 6 is provided with three solenoid valves 24 to 26 for speed change control. However, other solenoid valves for lock-up clutch control and line pressure control may be provided. .
[0014]
A battery 8 is connected to the motor control controller 22 to drive the motor generator 7 in a timely manner, 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 of the present invention. These time charts show a change in vehicle speed, a brake operation, and an engine control when the vehicle is stopped after the brake is pumped from the deceleration state of the vehicle.
In FIG. 2, when the brake is turned on at time t1, a deceleration fuel cut is performed, and the vehicle speed decreases. Since the fuel supply is stopped even if the engine speed drops below the idle speed at time t2, the 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 that of the conventional example (see FIG. 5).
When the brake is turned on again at time t4 immediately after time t3, the brake OFF time Δt is shorter than the predetermined time, so that it is determined that the operation is a pumping operation. If the pumping operation is determined, the engine is allowed to stop. 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, when the brake is turned off at time t6 and the accelerator pedal is depressed, 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 be stopped if it was originally, but in this case, the engine is frequently stopped and restarted during a traffic jam or the like. Result. 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 about 10 to 15 km / h, for example.
[0017]
In the present invention, the brake pumping operation 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 at the time of traffic jams, so that the brake operation at the time of traffic jams is not erroneously determined as a pumping operation.
In order to determine the pumping operation, it may be determined that there is no accelerator operation during the brake OFF period instead of comparing the brake OFF time Δt with a predetermined time. That is, the pumping operation is an operation for decelerating, and if there is an accelerator operation in the middle, it is determined that there is an intention to accelerate and can be distinguished from the pumping operation. Further, the pumping operation may be determined from both conditions of comparing the brake OFF time Δt with a predetermined time and the absence of the accelerator operation during the brake OFF period. In this case, the pumping operation can be determined more reliably.
[0018]
FIG. 4 is a flowchart of an example in which idle stop control is performed during traveling in the D range.
When the control starts, it is determined whether or not the engine stop condition is satisfied (step S1). As the engine stop condition, for example, the shift position is the D range, the brake is ON, and the battery capacity is sufficient. If the engine stop condition is not satisfied, the 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 exceeds a predetermined value Vo (vehicle speed history) after the engine is started (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, 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 is pumped (pumping operation history) (step S5). If there is a history of pumping operations, fuel cut is performed (step S4) and the engine is stopped. If there is no history of pumping operations, fuel injection is continued (step S2) and the engine is continuously driven. Therefore, it is possible to eliminate a situation where the engine is frequently stopped and restarted in a traffic jam.
[0019]
The present invention is not limited to the above embodiments.
In the above embodiment, the brake ON / OFF detection is performed using the brake switch. However, the brake operation may be detected by setting the brake ON when the brake fluid pressure is equal to or higher than the threshold value, and setting the brake OFF when the brake fluid pressure is lower than the threshold value. .
In the above embodiment, the hybrid vehicle including the 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 the engine and the automatic transmission.
The automatic transmission of 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 apparent from the above description, according to the invention described in claim 1, whether or not to stop the engine is determined based on whether or not the brake is pumped. Even after stopping after the pumping operation, the engine can be stopped, and 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 showing an example of engine stop control according to the present invention.
FIG. 3 is a time chart showing an example of engine stop control following FIG. 2;
FIG. 4 is a flowchart showing an example of engine stop control according to the present invention.
FIG. 5 is a time chart showing an example of conventional engine stop control.
[Explanation 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,
An automatic transmission that transmits the driving force of the engine to the drive wheels;
Shift position detecting means for detecting the shift position of the automatic transmission;
Brake operation detection means for detecting the driver's brake operation;
Vehicle speed detection means for detecting the vehicle speed;
A shift position is a drive range, and when satisfying the predetermined engine stop conditions including during deceleration of the brake ON, to allow the stop of the engine, and engine control means for Ru to restart the engine when the brake OFF, the In the automobile engine stop control device provided,
Providing a pumping operation detecting means for detecting the pumping operation of the brake;
After the engine is started, when the vehicle speed detected by the vehicle speed detection means exceeds a predetermined value, the engine control means permits the engine to stop,
After the engine is started, when the vehicle speed detected by the vehicle speed detection means is less than a predetermined value and the pumping operation detection means detects a pumping operation of the brake, the engine control means allows the engine to stop.
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 engine control means prohibits the engine from being stopped. Automobile engine stop control device. In the pumping operation detection means, 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. The engine stop control device for an automobile according to claim 1, wherein a pumping operation of the brake is detected.

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