JPS6218331A - Constant speed running device for vehicle - Google Patents

Abstract

PURPOSE:To change a vehicle speed smoothly with the provision of improved feeling by setting a set vehicle speed to be lower than a present vehicle speed by the specified amount when a coasting (slow down) switch is turned on in a device which controls the set vehicle speed automatically. CONSTITUTION:A device as referred to the title includes a frequency voltage covnerter (FVC) 1 in which a frequency which is proportional to a vehicle speed, allows change in vehicle speed to be converted into analogue voltage (present vehicle speed), a memory 2 which stores a set vehicle speed M, a duty generating circuit 3 which converts a difference between the set vehicle speed M and a present vehicle speed V into a control duty D, and a throttle control actuator which is driven by electric current in a pulse form having a control duty D. A writing switch 7 is turned on upon turning-on of a coast switch 5, the set vehicle speed M in the memory 2 is changed. In this case, a constant value DELTAV is subtracted by a subtracter allowing a value (V-DELTAV) to be written into the memory 2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a constant speed traveling device for automobiles that automatically controls a set vehicle speed, and is particularly intended to eliminate undershoot during coasting (deceleration) operation. .

[Conventional technology]

Autodrive, which automatically controls the throttle opening to drive the car at a set speed (memory speed), has a function that reduces the set speed without pressing the brake pedal. This is activated by turning on a manual switch called a coast switch, and during this period, the vehicle speed is gradually decreased regardless of the previously set vehicle speed, and at the same time, the set vehicle speed in the memory is updated with the current vehicle speed obtained sequentially. It is. Therefore, the relationship between coast inch and vehicle speed is as shown in FIG.

In the figure, the coast switch is turned on (ON) while the vehicle is traveling at a steady speed or in a hesitation manner at a vehicle speed v1, and the switch is turned off (OFF) when the vehicle speed reaches V2.

As a result, the set vehicle speed in the memory is updated from vl to ■2, and from now on, constant speed driving control is performed with v2 as the target value.

[Problem that the invention seeks to solve]

However, in reality, due to the inertia of the mechanical system, even when the coast switch is turned off, the vehicle speed does not immediately stop changing, but once drops to V3, then increases to ■2, and shifts to constant speed running. Undersea 2.1 at such vehicle speed
- (shaded area) has the disadvantage of giving the passenger a sense of discomfort. The present invention attempts to improve this point.

[Means for solving problems]

The present invention compares the current vehicle speed obtained at each point in time with the set vehicle speed in the memory, and controls the throttle control actuator on a duty basis so that the current vehicle speed matches the set vehicle speed, and at the same time operates a coast switch. In a constant speed driving system for an automobile, which performs duty control to forcibly reduce the current vehicle speed gradually during the period of time, and sequentially updates the set vehicle speed in the memory based on the current vehicle speed at each point in time, when the coast switch operation is performed. The present invention is characterized in that the set vehicle speed written in the memory is set to a value that is a certain value lower than the current vehicle speed.

[Effect]

By setting the set vehicle speed written in the memory when operating the coast switch to a value that is a certain value lower than the current vehicle speed, there will be no undershoot when transitioning to constant speed driving at the new set vehicle speed from the end of the switch operation. , the feeling improves. This will be explained in detail below with reference to illustrated embodiments.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention, and 1 is a frequency-voltage converter (1) that converts a vehicle speed signal whose frequency changes in proportion to the vehicle speed into an analog voltage (hereinafter referred to as the current vehicle speed). FVC), 2 is a memory that stores the set vehicle speed M, 3 is a duty generation circuit that converts the difference between the set vehicle speed M and the current vehicle speed V into a control duty D, and 4 is the duty D.
This is a throttle control actuator that is driven by a pulsed current. 5 is a manual coast switch, and when this is turned on, the output of gate 6 becomes duty O.
%, and the speed is decelerated regardless of the set vehicle speed M. At the same time, the write switch 7 from the FVCI to the memory 2 is also turned on, and as described in 1. Seven speeds 1-vehicle speed M in α device 2 are updated.

At this time, conventionally, the decreasing current vehicle speed V is directly written into the memory 2, but in this example, a constant value Δ■ is subtracted by the subtractor 8, and -ΔV is written into the memory 2.

This constant value .DELTA.V is ideally the overshoot l-min explained in FIG. If ΔV is too small, the effect of overshoot remains. On the other hand, if Δ■ is made too large, the overshoot will be eliminated, but this is inconvenient because the subsequent set vehicle speed will be much lower than the driver's desired vehicle speed (when the switch 5 is turned off). For this reason, a practically appropriate value for ΔV would be about 2 to 4 Km/h.

FIG. 2 is an explanatory diagram of the operation of the present invention, where ■2-Δ■ becomes the next set vehicle speed M. This is the maximum value v of speed change due to inertia
If it is less than or equal to 3, the undershoot is set to all (
The preset vehicle speed M=V due to smooth vehicle speed changes that do not occur
+ can be shifted to the next set vehicle speed M=V2-ΔV. Furthermore, if the inertia of the mechanical system is used inversely and the switch 5 is turned on for a short period of time, the current vehicle speed V will hardly increase, so M
It is possible to slightly decelerate from ="v'+ to M=V+-ΔV. Also, by repeating this 0 times, M=V1-n・ΔV
It can also be done.

〔Effect of the invention〕

As described above, according to the present invention, there is an advantage that the vehicle speed can be smoothly changed during the course (deceleration) control that lowers the set vehicle speed during constant speed driving, and the feeling can be improved. It is also possible to perform slight deceleration of 2 to 4 km/h.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of its operation, and FIG. 3 is an explanatory diagram of the operation of the conventional system. In the figure, 2 is a set vehicle speed memory, 3 is a duty generating circuit, 4 is an actuator, 5 is a coast switch, 7 is a write switch, and 8 is a constant value subtracter.

Claims (1)

[Claims] The current vehicle speed obtained at each point in time is compared with the set vehicle speed in the memory, and the duty of the throttle control actuator is controlled so that the current vehicle speed matches the set vehicle speed. In a constant speed driving system for an automobile, which performs duty control to gradually reduce the current vehicle speed and sequentially updates the set vehicle speed in the memory based on the current vehicle speed at each point in time, the information is written in the memory when the coast switch is operated. A constant speed traveling device for an automobile, characterized in that the set vehicle speed is set to a value lower than the current vehicle speed by a certain value.