JP2001207882A - Follow-up travel device and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent a nose dive phenomenon just before stopping. SOLUTION: A judgment is made that a preceding vehicle stops from an inter-vehicle distance between one's own vehicle and the preceding vehicle detected by an inter-vehicle distance sensor 1 and a time change in one's own vehicle speed detected by a wheel speed sensor 2 (YES of S1). A reference speed at which creep force exceeds braking force by an engine brake is derived (S2). The one's own vehicle speed detected by the wheel speed sensor 2 becomes the reference speed or less (YES of S3), and when the inter-vehicle distance to the preceding vehicle becomes a target inter-vehicle distance or less according to the one's own vehicle speed at that time (S4), a shift position of an automatic transmission is forcedly switched to a neutral range (YES of S5, S6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a follow-up traveling device which detects a distance between a preceding vehicle traveling in the same lane as the own vehicle and a vehicle, and maintains the inter-vehicle distance at or above a target distance corresponding to the own vehicle speed, and a control method therefor. .

[0002]

2. Description of the Related Art As one of safe driving assist devices mounted on an automobile, there is a follow-up traveling device called an inter-vehicle distance control type constant speed traveling device. Conventionally, this type of follow-up traveling device has conventionally been, for example, 60 m, 10 m when the vehicle speed is 50 km / h.
At 0 km / h, the target inter-vehicle distance is determined according to the vehicle speed of the own vehicle, such as 100 m, and the inter-vehicle distance between the own vehicle and a preceding vehicle traveling in the same lane is detected by the inter-vehicle distance detecting means. Is smaller than the target inter-vehicle distance, the throttle valve is closed to reduce the speed, and control is performed to maintain the inter-vehicle distance at or above the target inter-vehicle distance.

[0003]

However, in such a follow-up traveling device, when the own vehicle is also stopped along with the stop of the preceding vehicle, especially when the own vehicle is an automatic vehicle, the own vehicle decelerates. Immediately before stopping, the creep force exceeds the braking force of the engine brake, and in order to overcome the creep force and stop, the brake must be depressed strongly to generate a braking force greater than the creep force.

[0004] As a result, when stopping, a nose dive phenomenon referred to as so-called "cuck-on brake" has occurred, leading to deterioration in ride comfort.

Japanese Patent Laid-Open Publication No. Hei 10-159966 discloses an invention in which an automatic transmission is controlled to a neutral or parking state on condition that the host vehicle is stopped and an accelerator pedal is not depressed. However, this is a technique for reducing the battery load, the driver load, and other loads when the vehicle is stopped, and improving the fuel consumption. It does not prevent the nose dive phenomenon referred to as "".

Accordingly, an object of the present invention is to surely prevent the nose dive phenomenon immediately before stopping.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a follow-up traveling apparatus according to the present invention detects the distance between a preceding vehicle traveling in the same lane as the own vehicle and the inter-vehicle distance, and determines the inter-vehicle distance as the own vehicle speed. A following distance that is equal to or greater than a target distance according to the following distance: inter-vehicle distance detecting means for detecting the inter-vehicle distance between the own vehicle and the preceding vehicle; vehicle speed detecting means for detecting the speed of the own vehicle; A reference speed at which the creep force will be greater than the reference vehicle speed, a determination is made that the preceding vehicle has stopped based on the detection results by the inter-vehicle distance detection means and the vehicle speed detection means, and the own vehicle speed detected by the vehicle speed detection means Control means for outputting a switching control signal on condition that the speed is reduced to the reference speed, and the shift position of the automatic transmission is set to a neutral position by the switching control signal. It is characterized by comprising a switching means for switching to.

[0008] According to this configuration, when it is determined from the detection results by the following distance detecting means and the vehicle speed detecting means that the preceding vehicle has stopped, the own vehicle speed has a creep force higher than the braking force by the engine brake. When the speed decreases to the reference speed, the switching means is controlled by the switching control signal from the control means, and the shift position of the automatic transmission is automatically switched to the neutral state.

Therefore, when the vehicle is decelerated to a reference speed at which the creep force exceeds the braking force of the engine brake, the shift position of the automatic transmission is switched to the neutral state, and thereafter the creep force is not applied. Even if the brake is not depressed, a smooth stop can be realized with the depressed amount up to that time or with a depressed amount less than that without causing the nose dive phenomenon as in the related art.

Further, the following traveling apparatus according to the present invention includes gradient detecting means for detecting a gradient of a road on which the own vehicle is traveling, and the control means includes a gradient detected by the gradient detecting means and an engine speed. The reference speed is predicted from the engine speed detected by the detection means.

According to such a configuration, it is possible to predict the reference speed at which the creep force will be greater than the braking force by the engine brake, taking into account the gradient of the traveling road detected by the gradient detecting means. Therefore, the shift position of the automatic transmission can be switched to the neutral state at a timing that matches the current driving situation.

Further, the control method of the following traveling device according to the present invention predicts a reference speed at which the creep force will be higher than the braking force by the engine brake, detects the stop of the preceding vehicle, and reduces the speed of the own vehicle. The shift position of the automatic transmission is switched to a neutral state on condition that the speed decreases to the reference speed.

According to such a configuration, when the preceding vehicle stops and the own vehicle speed decreases to a vehicle speed at which the creep force exceeds the braking force by the engine brake,
Since the shift position of the automatic transmission is automatically switched to the neutral state, the creep force does not work after the shift position is switched to the neutral state. By maintaining this, a smooth stop can be realized without causing a nose dive phenomenon as in the related art.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a follow-up traveling device according to the present invention will be described with reference to FIGS.
1 is a block diagram, and FIG. 2 is a flowchart for explaining the operation.

First, the overall configuration of the following traveling device will be described. As shown in FIG. 1, an inter-vehicle distance sensor 1, which is inter-vehicle distance detection means, is provided.
For example, it is constituted by a scan laser radar, irradiates a laser beam in front of the own vehicle and sets a predetermined angle (eg, 1 °)
Scanning is performed in the horizontal direction at a time, and the reflected light is received by a light receiver, and the inter-vehicle distance between the host vehicle and a preceding vehicle traveling in the same lane is detected from the time from the irradiation of the laser light to the reception of the reflected light. The time required for such one inter-vehicle distance detection process is a very short time of about 0.1 second.

A wheel speed sensor 2 serving as vehicle speed detecting means
As a result, the own vehicle speed is detected, and the acceleration of the own vehicle is detected from the number of output pulses of the wheel speed sensor 2 within a predetermined time. Further, the acceleration sensor 3 detects the acceleration of the vehicle, the stop lamp switch 4 detects the presence or absence of a brake operation, the throttle sensor 5 detects the opening of the throttle valve, and the accelerator sensor 6 detects the accelerator pedal. The presence or absence of depression is detected, and the shift position of the automatic transmission is detected by the shift lever switch 7. At this time,
By comparing the acceleration detected from the output of the wheel speed sensor 2 with the acceleration detected by the acceleration sensor 3, the gradient of the road on which the vehicle is traveling is detected based on the degree of rotation and the like. Function as gradient detecting means.

The signals from the sensors 1, 2, 5, 6 and the switches 4, 7 are taken in by an electronic control unit (hereinafter referred to as ECU) 9, and the ECU 9
The control of each unit is performed by.

More specifically, the ECU 9 controls the display of the display 11 composed of, for example, a liquid crystal display device,
In order to maintain the inter-vehicle distance with the preceding vehicle at the target distance, drive control of the brake actuator 12 is performed, and when the brake actuator 12 is driven and automatic braking is applied, lighting control of the stop lamp 13 is performed, and electronic control is performed. The opening degree control of the throttle 14 is also performed.

Although not shown in FIG. 1, an electronically controlled fuel injection device and an engine speed detecting means for detecting the engine speed are mounted, and the ECU 9 also controls the electronically controlled fuel injection device. Will be At this time, it is derived from the engine speed detected by the engine speed detecting means as a reference speed at which the creep force will be higher than the braking force by the engine brake.

Further, the inter-vehicle distance sensor 1 is controlled by the ECU 9.
It is determined whether or not the preceding vehicle has stopped based on the detection result by the wheel speed sensor 2. When it is determined that the preceding vehicle has stopped, the own vehicle speed by the wheel speed sensor 2 has decreased to the reference speed described above. Is determined by the ECU 9, a switching control signal is output from the ECU 9 to the transmission switching unit 15 as switching means for switching the shift position of the automatic transmission, and the transmission shift unit 15 forcibly switches the shift position to the neutral state. Can be The output processing of the switching control signal by the ECU 9 corresponds to the control means.

As described above, when the vehicle speed decreases to the reference speed at which the creep force exceeds the braking force by the engine brake, the shift position of the automatic transmission is automatically switched to the neutral state by the switching control signal from the ECU 9, and thereafter, Since the creep force is not applied, the driver does not need to depress the brake more than necessary, and a smooth stop can be achieved.

Next, the operation will be described with reference to the flowchart of FIG. As shown in FIG. 2, based on the inter-vehicle distance between the own vehicle and the preceding vehicle detected by the inter-vehicle distance sensor 1 and the temporal change in the own vehicle speed detected by the wheel speed sensor 2, whether the preceding vehicle has stopped is determined. Is determined (S
1) If the result of the determination is NO, the operation is terminated as it is, and if the result of the determination is YES, the road gradient during traveling is
From the engine speed detected by the engine speed detecting means, a reference speed at which the creep force exceeds the braking force by the engine brake is derived by calculation (S2).

Subsequently, it is determined whether or not the vehicle speed detected by the wheel speed sensor 2 has become equal to or less than the reference speed described above (S3). If the result is YES, it is determined whether the inter-vehicle distance to the preceding vehicle detected by the inter-vehicle distance sensor 1 is equal to or less than a target distance corresponding to the own vehicle speed at that time (S4).

The result of the determination in step S4 is N
If it is O, the operation is terminated as it is, and if the determination result is YES, it is determined whether or not the shift position of the automatic transmission detected by the shift position switch 7 is in the "drive (D) range" (S5). ),
If the result of the determination is NO, the operation ends as it is, and if the result of the determination is YES, a switching control signal is output from the ECU 9 to the transmission switching unit 15 to forcibly switch the shift position to the neutral range (S
6) Then, the operation ends.

Therefore, according to the above-described embodiment, from the detection results obtained by the following distance sensor 1 and the wheel speed sensor 2,
The shift position of the automatic transmission is automatically switched to the neutral range on condition that the preceding vehicle stops and the vehicle speed drops to the reference speed, so that the creep force exceeds the braking force by the engine brake to the reference speed. When the vehicle decelerates, the creep force does not act after the shift position is switched to the neutral state, so the driver can use the conventional amount of depression or less, without depressing the brake more than necessary. A smooth stop can be realized without such a nose dive phenomenon.

Further, since the speed at which idle-up control is started by the electronically controlled fuel injection device is predicted as a reference speed from the detected engine speed, the switching control signal from the ECU 9 at the start timing of idle-up control. Is output, the shift position of the automatic transmission can be switched to the neutral state with a timing accuracy at which the creep force exceeds the braking force by the engine brake.

Further, taking into account the gradient of the road on which the vehicle is traveling, the reference speed at which the creep force exceeds the braking force of the engine brake is predicted. The position can be switched to a neutral state.

When the start of the preceding vehicle is detected,
The ECU 9 may control the transmission switching unit 15 to switch the shift position from neutral to a D (drive) range. At this time, for example, if the inter-vehicle distance detected by the inter-vehicle distance sensor 1 increases while the own vehicle is stopped, it can be realized by determining that the preceding vehicle has started.

Further, in the above-described embodiment, a case is described in which the control is performed in consideration of the gradient of the road on which the vehicle is traveling. However, it is not always necessary to consider the road gradient on which the vehicle is traveling.

Further, based on the inter-vehicle distance to the preceding vehicle detected by the inter-vehicle distance sensor 1 and the own vehicle speed by the wheel speed sensor 2, the inter-vehicle distance, which is the time difference from the current position to the current position of the preceding vehicle, is calculated. ECU with function to detect time
9 in place of the above-mentioned inter-vehicle distance, a determination may be made based on the inter-vehicle time to determine whether or not the preceding vehicle is stopped. In this case, the same effect as in the above-described embodiment can be obtained. It is.

The present invention is not limited to the above embodiment, and various changes other than those described above can be made without departing from the gist of the present invention.

[0032]

As described above, according to the first and third aspects of the present invention, when the speed is reduced to a level where the creep force exceeds the braking force by the engine brake, the shift position of the automatic transmission is switched to the neutral state. Therefore, since the creep force is no longer applied, the driver can smoothly stop without causing the nose dive phenomenon without stepping on the brake more than necessary, with the amount of depression until then or less. And a stable stopping performance can be obtained.

According to the second aspect of the present invention, the reference speed at which the creep force will be greater than the braking force due to the engine brake, taking into account the gradient of the traveling road detected by the gradient detecting means. Can be predicted, so that the shift position of the automatic transmission can be switched to the neutral state at a timing that matches the current driving situation.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment of the present invention;

[Explanation of symbols]

 1 inter-vehicle distance sensor (inter-vehicle distance detecting means) 2 wheel speed sensor (vehicle speed detecting means, gradient detecting means) 3 acceleration sensor (gradient detecting means) 9 ECU (control means) 15 transmission switching section (switching means)

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Claims (3)

[Claims] 1. A follow-up traveling device that detects an inter-vehicle distance between a preceding vehicle traveling in the same lane as the own vehicle and a vehicle and maintains the inter-vehicle distance equal to or greater than a target distance according to the own vehicle speed. An inter-vehicle distance detecting means for detecting an inter-vehicle distance; a vehicle speed detecting means for detecting a vehicle speed of the own vehicle; a reference speed at which a creep force will be higher than a braking force by an engine brake; Control means for judging that the preceding vehicle has stopped from the detection result by the vehicle speed detection means, and outputting a switching control signal on condition that the own vehicle speed detected by the vehicle speed detection means decreases to the reference speed; A switching means for switching a shift position of the automatic transmission to a neutral state according to the switching control signal. 2. The vehicle according to claim 1, further comprising a gradient detector for detecting a gradient of a road on which the vehicle is traveling, wherein the controller detects a gradient detected by the gradient detector and an engine speed detected by the engine speed detector. The following traveling apparatus according to claim 1, wherein the reference speed is predicted from the following. 3. A control method of a following-traveling device for detecting an inter-vehicle distance between a preceding vehicle traveling in the same lane as a host vehicle and a target vehicle and maintaining the inter-vehicle distance equal to or greater than a target distance corresponding to the host vehicle speed. Predicting a reference speed at which the creep force will be greater than that of the preceding vehicle, detecting the stop of the preceding vehicle, and switching the shift position of the automatic transmission to a neutral state on condition that the own vehicle speed decreases to the reference speed. A method for controlling a following travel device, characterized by comprising: