JP3557890B2 - Inter-vehicle distance control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inter-vehicle distance control device that controls a braking device independently of a driver's operation to prevent a rear-end collision with a preceding vehicle.
[0002]
[Prior art]
In order to improve safety, automobiles (vehicles) have been equipped with an inter-vehicle distance control device that operates a braking device independently of the driver's intention to avoid a collision with a preceding vehicle. I have.
[0003]
Such an inter-vehicle distance control device calculates an inter-vehicle distance deviation and a relative speed by using the own vehicle speed detected by a vehicle speed sensor or the like and the inter-vehicle distance to a preceding vehicle detected by a laser radar device or the like. When the distance between the vehicle and the vehicle is short, there is a braking device that activates an auxiliary brake such as an exhaust brake, a retarder, and a compression-pressure release type engine auxiliary brake based on the detection information.
[0004]
Specifically, as disclosed in JP-A-6-278500, when the inter-vehicle distance between the preceding vehicle and the own vehicle is shortened, various types of braking with different braking capabilities such as engine braking, fuel cut, exhaust braking, and the like are performed in stages. It is also known to operate a device to apply a braking force to a vehicle independently of a driver's intention and to maintain a safe inter-vehicle distance.
[0005]
[Problems to be solved by the invention]
Such an inter-vehicle distance control device plays a predetermined role when the vehicle returns to a safe state by the operation of the braking device, and thus releases the operation of the braking device.
By the way, conditions for releasing the operation of such a braking device are almost uniformly determined. Specifically, the operation of the braking device is released by setting the release timing in consideration of running on a flat road.
[0006]
However, with such a uniform release timing, a braking device that avoids a rear-end collision with a preceding vehicle when traveling on a road other than the expected road surface, particularly when traveling on a downhill road. And the release of the braking device for return frequently occur.
[0007]
In other words, when traveling on a downhill road, when the possibility of a collision with the preceding vehicle is eliminated by the operation of the braking device and the operation of the braking device is released, the acceleration of the own vehicle increases due to the downhill. Show behavior. Therefore, when there is no possibility of a rear-end collision, the control in which the braking device is immediately released and the operation is performed again thereafter is repeated in a short cycle.
[0008]
For this reason, on a downhill road, the feeling is quite bad unlike on a flat road.
Therefore, it is conceivable to delay the timing of releasing the operation of the braking device and set it slightly.
[0009]
However, this causes a problem that the operation of the braking device is not easily released on a flat road, which is a normal time, and the occupant feels a sense of discomfort.
For this reason, it is desired to release the operation of the braking device in consideration of both normal traveling and traveling on a downhill road.
[0010]
The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a good head feeling inter-vehicle control for a preceding vehicle with a good feeling without losing the normal inter-vehicle control. An object of the present invention is to provide a distance control device.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, an inter-vehicle distance control device according to claim 1 is a control device for a flat road in which an operation region and a release region of a braking device are set according to a relative speed with respect to a preceding vehicle and an inter-vehicle distance deviation. A control map and a downhill road control map in which the reference relative speed that defines the release area of the flat road control map is shifted to the negative side. Normally, the operation of various braking devices is performed according to the flat road control map. If the downhill road determination means detects that the vehicle is traveling on a downhill road, the operation of the various braking devices is controlled according to the release area of the downhill road control map to activate the various braking devices. The structure that reduces the sensitivity to return to the non-operation state from the normal state compared to the normal state is adopted, even if the possibility of collision with the preceding vehicle is eliminated by the operation of the braking device while driving on a downhill road, the braking device is immediately Is non Not to return to the dynamic state, without changing the timing of the actuation / release of the normal braking device, the descent time was prevented repeated in releasing the actuation and a short period of braking device.
In the headway control device according to claim 2, the braking device has at least two of an exhaust brake, a compression-release type engine auxiliary brake and a retarder, and the control means operates each braking device in a stepwise manner. It has a function to return from the state to the inactive state.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on an embodiment shown in FIGS.
In FIG. 1, reference numeral 1 denotes an automobile (vehicle) on which a traveling engine (not shown) is mounted, and 2 denotes an inter-vehicle distance control apparatus mounted on the automobile 1.
[0013]
The inter-vehicle distance control device 2 has a controller 3 (corresponding to control means) constituted by, for example, a microcomputer. The controller 3 is connected to a vehicle speed sensor 4 (corresponding to a vehicle speed detecting means) for detecting the vehicle speed of the own vehicle 1. Further, the controller 3 is connected to an inter-vehicle distance detecting means mounted on the vehicle, for example, a laser radar unit 5 for capturing a laser beam reflected from a reflector (not shown) of the preceding vehicle X, and an output of the laser radar unit 5. From the preceding vehicle X, and the relative speed with respect to the preceding vehicle X is calculated based on the amount of change in the detected inter-vehicle distance per unit time. Further, the controller 3 is connected to an auxiliary brake 6 (corresponding to a braking device capable of applying a braking force independently of the driver's intention) constituted by, for example, various braking devices having different braking capabilities. The auxiliary brake 6 includes, for example, an exhaust brake, a compression-pressure release type engine auxiliary brake (hereinafter simply referred to as an engine auxiliary brake), a retarder, and the like.
[0014]
The controller 3 has a function of calculating a relative speed with respect to the preceding vehicle X and a function of calculating a deviation between the target inter-vehicle distance corresponding to the own vehicle speed and the actual inter-vehicle distance with respect to the preceding vehicle X. Further, the controller 3 is provided with a flat road control map in which the operation / release timing of the auxiliary brake 6 is set in consideration of running on a flat road which is a normal time. More specifically, an exhaust control map formed at the timing of operation (ON area) / release (OFF area) of the exhaust brake, which is set with the running on a flat road as shown in FIG. FIG. 2 (b) is an engine auxiliary brake control map formed at the timing of operation (ON area) / release (OFF area) of the engine auxiliary brake, which is also set with the running on a flat road in mind. The retarder control map formed at the timing of the operation (ON area) / cancellation (OFF area) of the retarder, which is also set in consideration of traveling on a flat road as shown in c), is set.
[0015]
Further, based on the obtained inter-vehicle distance deviation / relative speed with respect to the preceding vehicle X, when the vehicle falls below a target predetermined inter-vehicle distance, the controller 3 performs various braking operations in accordance with each of the exhaust control map, the engine auxiliary brake control map, and the retarder control map. A function is set to operate / release the device step by step, and when the distance between the vehicle and the preceding vehicle X becomes short, an exhaust brake, an engine auxiliary brake, and a retarder (all of which are operated independently of the driver's intention) ) Is generated so that a rear-end collision with the preceding vehicle X is avoided.
[0016]
In addition, a control map for a downhill road is set in the controller 3 in addition to a control map in a normal state (when running on a flat road is considered). This downhill road control map is a sensitivity for returning the auxiliary brake 6 from the operating state (ON) to the non-operating state (OFF) in the control map of the normal state (when running on a flat road is considered). It is a map in which is reduced. Specifically, as the downhill road control map, the reference relative speed α defining the release (OFF) region in the exhaust control map of FIG. 2A as shown in FIG. The engine assist brake in which the reference relative speed β defining the release (OFF) region in the engine assist brake control map of FIG. 2B as shown in FIG. 2E is shifted to the negative side. As shown in FIG. 2F, a retarder control map in which the reference relative speed γ defining the release (OFF) region in the retarder control map of FIG. 2C is shifted to the negative side. 2 (a) to 2 (e) and FIGS. 2 (d) to 2 (f), the sensitivity of the auxiliary brake 6 from the non-operation state (OFF) to the operation state (ON) is normal. It is the same when going downhill.
[0017]
Further, the controller 3 has a function of detecting whether or not the vehicle 1 is accelerating (for example, whether or not the vehicle 1 accelerates by 0.5 km / h or more per second) from the change in the relative speed during the operation of the auxiliary brake 6. Is set. With this function, it is detected whether or not the vehicle 1 is traveling on a downhill road (corresponding to a downhill determination unit).
[0018]
When the controller 3 receives the detection of the traveling on the downhill road, the controller 3 controls the operation of each brake stepwise according to the downhill road control map (exhibit / engine auxiliary brake / retarder) shown in FIGS. If the function of releasing is set, and the possibility of the rear-end collision with the preceding vehicle X is eliminated by the operation of the auxiliary brake 6 (exhaust / engine auxiliary brake / retarder) when going downhill, the auxiliary brake 6 (exit / Engine auxiliary brake / retarder) is not released.
[0019]
The operation of the inter-vehicle distance control device during such a downhill is shown in the flowchart of FIG.
Next, the flowchart will be described. It is assumed that, for example, the own vehicle 1 is traveling on a downhill following the preceding vehicle X as shown in FIG.
[0020]
At this time, the controller 3 mounted on the own vehicle 1 monitors the inter-vehicle distance from the preceding vehicle X from the output of the laser radar unit 5.
Here, it is assumed that the own vehicle 1 approaches the preceding vehicle X while gradually accelerating on the downhill.
[0021]
The controller 3 reads the own vehicle speed detected by the vehicle speed sensor 4 and the actual inter-vehicle distance detected by the laser radar unit 5, and calculates a deviation between the preceding vehicle X with respect to the target inter-vehicle distance and a relative speed with the preceding vehicle X. If it is determined that the operation condition of the auxiliary brake is satisfied, the process proceeds from step S1 to step S2, where the auxiliary brake 6 is operated independently of the driver's intention. Specifically, in the present embodiment, the operation (on) region of the exhaust control map of FIG. 2A and the operation (ON) region of FIG. The exhaust brake, the engine auxiliary brake, and the retarder are operated based on the operation (ON) area of the engine auxiliary brake control map and the operation (ON) area of the retarder control map of FIG.
[0022]
The own vehicle 1 is decelerated by the braking force applied from the auxiliary brake 6 (exhaust brake, engine auxiliary brake, retarder), and the inter-vehicle distance with the preceding vehicle X is set to a predetermined value due to the decrease in the relative speed with respect to the preceding vehicle X. The possibility of the own vehicle 1 colliding with the preceding vehicle X is avoided.
[0023]
Next, the operation of the auxiliary brake 6 is released.
At the time of this release, a downhill road control map having a lower sensitivity than normal (a flat road control map) is used.
[0024]
That is, during the application of the braking force by the auxiliary brake 6, in step S3, it is detected whether the vehicle 1 is accelerating (for example, accelerating 0.5 km / h or more per second).
[0025]
The controller 3 determines that the vehicle is traveling on a downhill road when the vehicle is accelerating even if the auxiliary brake is operating, and proceeds to step S4, where the controller 3 performs the descending operation shown in FIGS. 2 (d) to 2 (f). The control map for the slope is selected, and the release of the operation of the auxiliary brake 6 (the exhaust brake, the engine auxiliary brake, the retarder) is delegated to the control map for the downhill road (the exhaust control map, the engine auxiliary brake control map, the retarder control map). If the vehicle is traveling on a flat road, the process proceeds to step S5, and the operation release of the auxiliary brake 6 is referred to a flat road control map (an exhaust control map, an engine auxiliary brake control map, a retarder control map).
[0026]
Here, in the downhill road control map, since the ON-OFF hysteresis is increased to reduce the sensitivity of returning to the operation release (OFF), it is possible to collide with the preceding vehicle X by operating the auxiliary brake 6. Even if the performance is eliminated, the auxiliary brake 6 does not immediately return to the release state as shown in the diagram of FIG.
[0027]
That is, as shown by the ON state of each exhaust, the engine auxiliary brake, and the retarder in FIG. 3, the relative speed with respect to the preceding vehicle X becomes close to zero, and even if the auxiliary brake release condition on a flat road is satisfied, the auxiliary is maintained. The operation state of the brake 6 continues, and the auxiliary brake 6 (exhaust brake, engine auxiliary brake, retarder) is not released immediately. Therefore, the behavior in which the release and operation of the auxiliary brake 6 are repeated in a short cycle is eliminated.
[0028]
Therefore, when descending a hill, the own vehicle 1 does not unnecessarily approach the preceding vehicle X while repeatedly operating / releasing in a short cycle, and the headway control for the preceding vehicle X can be performed with a good feeling.
[0029]
In addition, since the sensitivity of the operation / release of the auxiliary brake 6 in the normal state is not changed, the operation / release of the auxiliary brake 6 on a flat road is not changed, and there is no uncomfortable feeling.
[0030]
In one embodiment, the sensitivity for returning from the operating state of the auxiliary brake to the released state is reduced from the normal state by changing the reference relative speed that defines the release of the auxiliary brake. However, the present invention is not limited to this. Both the reference relative speed defining the release of the brake and the inter-vehicle distance deviation may be changed.
[0031]
Further, in one embodiment, an auxiliary brake in which three braking devices (exhaust brake, engine auxiliary brake, and retarder) are combined is taken as an example. The auxiliary brake used may be one using a braking device of another type.
[0032]
【The invention's effect】
As described above, according to the present invention, even when the possibility of a rear-end collision with the preceding vehicle is eliminated by the inter-vehicle distance control by the driving device during a descent, the braking device does not immediately return to the non-operation state. When the vehicle is on a slope, the release and operation of the braking device can be prevented from being repeated in a short cycle.
[0033]
Therefore, the headway control for the preceding vehicle can be performed with a good feeling. In addition, since the operation / release timing of the braking device in the normal state is not changed, there is no sense of incongruity in the inter-vehicle distance control in the normal state.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of an inter-vehicle distance control device according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining operation / release of an auxiliary brake (braking device) of the device.
FIG. 3 is a diagram showing a state of release of an auxiliary brake when descending a slope, together with a situation of a host vehicle and a preceding vehicle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Own vehicle 2 ... Inter-vehicle distance control device 3 ... Controller (Control means, downhill road determination means)
4: Vehicle speed sensor (vehicle speed detecting means)
5. Laser radar (inter-vehicle distance detecting means)
6. Auxiliary brake (braking device)
X: The preceding car.

Claims (2)

Vehicle speed detecting means for detecting a vehicle speed;
An inter-vehicle distance detecting means for detecting an inter-vehicle distance with a preceding vehicle;
A braking device that is provided so as to be able to apply a braking force independently of the driver's will, and includes at least one of an exhaust brake, a compression-pressure-released engine auxiliary brake, and a retarder,
An inter-vehicle distance control device comprising: control means for controlling the operation of the various braking devices so as to prevent a collision with the preceding vehicle based on detection information from the vehicle speed detection means and the inter-vehicle distance detection means.
It has downhill road determination means for detecting that the vehicle is traveling on a downhill road,
The control means defines a flat road control map in which an operation area and a release area of the braking device are set according to a relative speed with respect to a preceding vehicle and an inter-vehicle distance deviation, and defines the release area of the flat road control map. And a control map for a downhill road in which the reference relative speed is shifted to the negative side. In normal times, the operation of the various braking devices is controlled according to the control map for a flat road, and the vehicle is traveling on a downhill road by the downhill road determination means. If it is detected at the sensitivity for returning control to the various braking devices the operation of the various brake device according releasing region of the downhill control map from the operating state to the non-operating state to the normal state An inter-vehicle distance control device that is configured to lower the distance. The braking device has at least two of an exhaust brake, a compression-pressure-released engine auxiliary brake, and a retarder, and the control unit has a function of gradually returning each braking device from an operating state to a non-operating state. The inter-vehicle distance control device according to claim 1, wherein:

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