JPH08295150A - Autocruise control method - Google Patents

Abstract

PURPOSE: To reduce a set car speed surely regardless of any specific condition, by using the operating control of an auxiliary brake concurrently, when the set car speed is reduced at a specific ratio, in an autocruise running condition accompanying the operation control of the auxiliary brake. CONSTITUTION: When a set switch 3 is operated in the running condition of a vehicle, the autocruise control is started by making the car speed at that time as a set car speed. In a control unit 1, it is inferred that an operation to reduce the present car speed is carried out in order to reduce the set car speed when the set switch 3 is ON, the set car speed is reduced at a specific ratio, and the speed of the vehicle is reduced by an engine brake. It is decided whether the fuel feeding to an engine is zero or not, and when it is decided zero, an auxiliary brake 11 is operated. That is, an exhaust brake 12, a compression release type engine brake auxiliary device 13, and a retarder 14, to compose the auxiliary brake 11 are operated by combining them adequately, and the car speed is reduced by stages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle auto-cruise control method involving auxiliary brake operation control.

[0002]

2. Description of the Related Art Generally, a constant speed traveling device (auto cruise device) for traveling a vehicle at a constant speed adjusts an output of an engine based on a vehicle speed deviation which is a deviation between an actual vehicle speed of the vehicle and a set vehicle speed, It keeps the vehicle running at a constant speed. On the other hand, as disclosed in Japanese Utility Model Laid-Open No. 4-65624, there is known an auto-cruise device accompanied by operation control of an auxiliary brake. This is to use the control of the fuel supply amount and the braking control of the exhaust brake and the retarder when the vehicle is traveling at a constant speed. By using the auto-cruise device with the operation control of the auxiliary brake, it is difficult to drive the vehicle at a constant speed by controlling the fuel supply amount.For example, the vehicle is driven at a constant speed by controlling the operation of the auxiliary brake even on a downhill. Can be made.

When the set vehicle speed is decreased while the vehicle is traveling at a constant speed by the conventional auto cruise device, the vehicle is decelerated by operating the deceleration switch or the like, and the vehicle speed at the time when the vehicle speed reaches the desired vehicle speed is newly set. It is designed to run at a constant speed. That is, as shown in FIG. 5, while the deceleration switch is ON, the set vehicle speed is reduced at a constant rate, the vehicle is decelerated by putting the engine in the brake state, and when the deceleration switch changes from ON to OFF. The set vehicle speed is changed to the actual vehicle speed.

[0004]

In the conventional auto-cruise device, when the set vehicle speed is reduced, the vehicle speed is reduced by putting the vehicle in an engine brake state to decelerate and change the actual vehicle speed to a new set vehicle speed. Therefore, when trying to reduce the set vehicle speed while the vehicle is traveling downhill, the vehicle will decelerate even if the engine brake becomes maximum (in the case of a diesel engine, the fuel injection amount becomes 0). There was a risk of accelerating without doing so. As a result, there are cases in which the set vehicle speed cannot be reduced, and the driver may feel uncomfortable.

The present invention has been made in view of the above circumstances, and provides an automatic cruise control method capable of reliably reducing the set vehicle speed in any case when the set vehicle speed is reduced during the automatic cruise control. The purpose is to provide.

[0006]

An automatic cruise control method of the present invention for achieving the above object is to provide an automatic cruise control method of an auxiliary brake during vehicle automatic cruise travel.
When the set vehicle speed is reduced at a fixed ratio, the operation control of the auxiliary brake is also used.

The operation control of the auxiliary brake is as follows.
It is characterized in that it is executed when the engine braking of the vehicle becomes maximum. Further, the auxiliary brake has a braking force of a plurality of levels of strength. Further, the auxiliary brake is operated by gradually increasing the braking force according to the deviation between the set vehicle speed and the actual vehicle speed. Further, the auxiliary brake is released by gradually weakening a braking force according to a deviation between the set vehicle speed and an actual vehicle speed.

[0008]

When the set vehicle speed is reduced at a constant rate, the auxiliary brake operation control is also used to surely decelerate the vehicle and reduce the set vehicle speed. Then, an auxiliary brake having a braking force of multiple levels is used when the engine brake is at its maximum, and the braking force of the auxiliary brake is gradually increased according to the vehicle speed deviation, thereby making it possible to reduce the slope downhill. Even when traveling, the vehicle is surely decelerated without any discomfort. Further, when the operation of the auxiliary brake is released, the braking force is gradually reduced according to the rate of change of the inter-vehicle distance, so that the braking force is released without any discomfort.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram of an auto-cruise device for carrying out an auto-cruise control method according to an embodiment of the present invention, and FIG. 2 is a flow chart of an auto-cruise control method according to an embodiment of the present invention. 3 shows the operation sequence of the auxiliary brake, and FIG. 4 shows the processing explanation of the auxiliary brake.

As shown in FIG. 1, a main switch 2 for auto cruise is connected to a control unit 1 of a vehicle such as a truck, and an operation signal for auto cruise control is sent to the control unit 1 by operating the main switch 2. Is entered. A set switch 3 is connected to the control unit 1, and the set switch 3 is used to set an auto cruise vehicle speed (set vehicle speed) and reduce the set vehicle speed. That is, when the set switch 3 is operated after the main switch 2 is operated, the vehicle speed at that time becomes the set vehicle speed, and when the set switch 3 is operated during the auto cruise traveling, the set switch 3 acts as a deceleration switch and The deceleration state of the vehicle is maintained during the operation. Further, a resume switch 4 is connected to the control unit 1, and the resume switch 4 is used for returning from the temporary cancellation of the automatic cruise and increasing the set vehicle speed.

The control unit 1 is also connected to an automatic cruise release switch 5 and an accelerator switch 6. The auto-cruise release switch 5 is closed by a clutch actuation signal or a transmission neutral signal. A signal from the stop lamp switch 7 and a vehicle speed signal from the vehicle speed sensor 8 are also input to the control unit 1, and the set vehicle speed and the current vehicle speed are compared.

The control unit 1 keeps the current vehicle speed at the set vehicle speed by turning on the cruise lamp 9 during the automatic cruise control while sending a signal to the actuator 10 of the engine (not shown) to increase or decrease the output of the engine. To control. Further, the control unit 1 controls the operation of the auxiliary brake 11 during the operation of the engine brake so as to maintain the current vehicle speed at the set vehicle speed.

The auxiliary brake 11 comprises an exhaust brake 12, a compression pressure release type engine brake auxiliary device 13 and a retarder 14. The exhaust brake 12 obtains a braking force by the exhaust flow resistance according to the throttle of the exhaust pipe, and the compression pressure release type engine brake auxiliary device 13 is, for example, a third engine provided in an appropriate engine cylinder. The braking force is obtained by weakening the downward force of the piston that opens the valve from the compression stroke to the expansion stroke. The retarder 14 obtains a braking force by changing the blade angle of the stator in the fluid retarder to adjust the flow rate of the retarder and increasing the rotational resistance of the propeller shaft. The retarder 14 is not limited to the fluid type because the electrical resistance type or the like may be used in addition to the fluid type.

When the vehicle reaches a desired speed after the main switch 2 is closed while the vehicle is traveling, the vehicle speed at this time is set to the set vehicle speed by operating the set switch 3, and the automatic cruise control is started. It When the auto cruise control is started, the output of the engine is adjusted by the control of the actuator 10 by the control unit 1, and the current vehicle speed is maintained at the set vehicle speed. By operating the set switch 3 during execution of the auto cruise control, the vehicle is brought into an engine brake state and decelerated, and by operating the set switch 3 again, the vehicle speed at this time is set as a new set vehicle speed.

The control for reducing the set vehicle speed during execution of the auto cruise control will be described with reference to FIG.

As shown in FIG. 2, it is determined in step S1 whether or not the set switch 3 is ON. If it is determined that the set switch 3 is not ON, that is, the set switch 3 is OFF, Set switch 3 in step S2
It is determined whether has changed from ON to OFF. When it is determined in step S2 that the set switch 3 remains off, the auto cruise is executed at the current set vehicle speed. In step S2, the set switch 3 turns on
When it is determined that the set vehicle speed has changed to OFF, it is estimated that the deceleration operation for reducing the set vehicle speed is completed, the set vehicle speed is changed to the current actual vehicle speed in step S3, and the auto cruise is executed at the changed set vehicle speed.

On the other hand, in step S1, the set switch 3
If it is determined to be ON, it is estimated that the current vehicle speed is reduced in order to reduce the set vehicle speed, the set vehicle speed is reduced at a constant ratio in step S4, the engine output is reduced in step S5, and engine braking is performed. (Engine control)
To slow down the vehicle. In step S6, it is determined whether or not the fuel supply amount to the engine is 0, and when the fuel supply amount is not 0, that is, when the engine is in the deceleration state, the vehicle is decelerated as it is. When it is determined that the fuel supply amount to the engine is 0 in step S6, it is estimated that the vehicle is not decelerated (downhill traveling) by the engine control, and the auxiliary brake control is executed in step S7.

The auxiliary brake control in step S7 will be described with reference to FIGS. As shown in FIG.
The auxiliary brake 11 is set to operate in seven stages,
As shown in FIG. 5, the braking force is gradually increased each time the condition 1 is satisfied in the order from, and the braking force is gradually decreased each time the condition 2 is satisfied in the order from. To go. That is, the auxiliary brake 11 is operated stepwise so that the reduction rate of the vehicle speed falls within a predetermined range. still,
The order of the steps shown in FIG. 4 is an example, and may be variously changed depending on the vehicle speed and the gear stage during running.

When the auxiliary brake 11 operates stepwise,
Conditions 1 and 2 will be described. Let Vd be the rate of change in vehicle speed
In addition, the predetermined vehicle speed change rate by operating the set switch 3
Vd _max, Vd_minAnd the determination time is T,
Cases 1 and 2 are set by the following equation. Condition 1: d / dt (Vd) <(Vd_max-Vd_min) / T Condition 2: d / dt (Vd)> (Vd_max-Vd_min) / T

Therefore, when the set vehicle speed is decreased, the set vehicle speed is decreased at a constant rate, and the vehicle cannot be decelerated by the engine control, that is, when the engine brake is maximized, the vehicle is not decelerated. ,
Since the set vehicle speed is reduced by executing the auxiliary brake control to decelerate the vehicle, it is possible to reliably reduce the set vehicle speed even when the vehicle is traveling on a downhill. In addition, since the auxiliary brake control changes the braking force in a stepwise manner, the braking force of the auxiliary brake 11 does not suddenly change, and the vehicle can smoothly travel during deceleration. Become.

[0021]

According to the automatic cruise control method of the present invention, the auxiliary brake control is also used when the set vehicle speed is reduced at a constant rate. Therefore, the vehicle is reliably decelerated and the set vehicle speed is reduced. As a result, the set vehicle speed can be surely reduced in any case. In addition, the auxiliary brake, which has multiple levels of braking force, is used when the engine brake is at its maximum, and the braking force of the auxiliary brake is increased stepwise, so it is possible to drive downhill. Even if it is, the vehicle is surely decelerated without any discomfort. Further, when the operation of the auxiliary brake is released, the braking force is gradually weakened according to the change rate of the inter-vehicle distance, so that the braking force is released without any discomfort. As a result, in any case, the set vehicle speed can be surely reduced without any discomfort.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an auto cruise device for implementing an auto cruise control method according to an embodiment of the present invention.

FIG. 2 is a flowchart of an automatic cruise control method according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an operation sequence of an auxiliary brake.

FIG. 4 is a process explanatory diagram of an auxiliary brake.

FIG. 5 is a flowchart of a conventional auto cruise control method.

[Explanation of symbols]

 1 Control Unit 2 Main Switch for Auto Cruise 3 Set Switch 4 Resume Switch 5 Auto Cruise Release Switch 6 Accelerator Switch 7 Stop Lamp Switch 8 Vehicle Speed Sensor 9 Cruise Lamp 10 Actuator 11 Auxiliary Brake 12 Exhaust Brake 13 Compressed Pressure Releasing Engine Brake Auxiliary Device 14 retarder

Claims (5)

[Claims] 1. An automatic cruise control method, wherein during the automatic cruise traveling of a vehicle accompanied by an auxiliary brake operation control, the auxiliary brake operation control is also used when the set vehicle speed is reduced at a constant ratio. 2. The automatic cruise control method according to claim 1, wherein the operation control of the auxiliary brake is executed when the engine brake of the vehicle becomes maximum. 3. The automatic cruise control method according to claim 1, wherein the auxiliary brake has a braking force of a plurality of levels of strength. 4. The automatic cruise control method according to claim 3, wherein the auxiliary brake is operated by gradually increasing a braking force according to a deviation between the set vehicle speed and an actual vehicle speed. . 5. The automatic cruise control method according to claim 3, wherein the auxiliary brake is released by gradually weakening a braking force according to a deviation between the set vehicle speed and an actual vehicle speed. .