JPS6346929A - Constant speed running device - Google Patents

Abstract

PURPOSE:To prevent a car speed from generating its hunting action, by switching a device to a control of fixing a throttle opening when a vehicle is driven running fully closing a throttle on a downhill while the constant speed running device is in operation. CONSTITUTION:A comparator 14a in a compared output means 14 compares an actual car speed, processed in a processing unit 22, with the target car speed to output a difference DELTAV between these speeds. An output determining means 14b, which receives the difference DELTAV to determine a necessary duty for decreas ing this difference to zero, supplies a square wave pulse of said duty to an actuator 16 of a throttle valve. IN this way, a vehicle 18, which adjusts its speed, is driven approaching the target car speed. A discriminating means 24, if it discriminates action of hunting to be generated, generates an output fixing the duty output by the output determining means 14b. In this way, the car speed is prevented from generating its hunting action.

Description

[Detailed Description of the Invention] [Summary] When a car is running with a constant speed running device operating, it enters a downhill slope and cannot run unless the throttle opening is fully closed (if the throttle is opened even slightly, the speed will exceed the set speed). turn into)
In this case, control is switched to fix the throttle opening to prevent vehicle speed hunting.

[Industrial application field]

The present invention relates to a constant-speed traveling device for an automobile, and is intended to provide the constant-speed traveling device with a function of preventing vehicle speed hunting that may occur when the vehicle enters a downhill slope.

(Prior Art) It is known to detect the vehicle speed, find the difference between the vehicle speed and the target vehicle speed, and operate the throttle actuator based on the difference so that the vehicle travels at the target vehicle speed. can be entered by depressing the accelerator to bring the vehicle speed to the desired value, then releasing the accelerator to enter the vehicle, and after entering the constant speed driving condition, depressing the brake will release the constant speed driving condition. Can be done.

When the accelerator is pressed while driving at a constant speed, the vehicle speed increases, but the constant speed driving state is not canceled.The vehicle decelerates without releasing the accelerator and returns to the previous state, and continues driving at a constant speed. Furthermore, when the resume switch is turned on after the brake is released, the car speeds up and returns to the original constant speed driving state.

[Problem that the invention seeks to solve]

While driving with this constant speed traveling device, if the vehicle is traveling downhill where the vehicle cannot travel unless the throttle opening is close to fully closed, vehicle speed hunting occurs due to engine fuel loss when the throttle opening is fully closed. This occurs when the vehicle attempts to travel in an area where constant speed travel is not possible, as shown by the shaded area in FIG.

In this figure, the horizontal axis shows the slope of the downhill slope, and the vertical axis shows the vehicle speed.
The straight line ■ is the vehicle speed-gradient characteristic when the fuel is cut off (throttle opening fully closed, so the engine brake is working <), and the straight line ■ is the vehicle speed-gradient characteristic when the fuel is on (throttle opening fully closed + slight opening). . The shaded area between these straight lines is an area that cannot exist constantly. In other words, for example, in the case of a downhill slope of 5%, the vehicle speed will decrease when the throttle opening is fully closed.
1 For example, it becomes 70 Km/h, and it is Risurotsu I-
Open the door even slightly (■ and the vehicle speed is V2, for example 90 Km/
h, making it impossible to drive steadily at intermediate vehicle speeds such as 80 km/h. As shown in Figure 4, if the throttle opening is fully closed and the engine speed is at a certain value, the engine control device will cut off the fuel and open the engine a little more than fully closed.
When this happens, fuel injection starts (fuel on FO), but this is due to the step-like change in fuel amount between FC and FO. The subsequent change in fuel amount is proportional to the throttle opening.

In the above example, the target speed set for constant speed driving is 80km/h.
If so, the fuel cut ■ indicates that the vehicle speed is lower than the target speed (, and the fuel on ■ indicates that the vehicle speed is higher than the target speed (,
For this reason, the constant speed traveling device repeats ■ and ■, which causes hunting in the vehicle speed.

FIG. 5 fat shows this vehicle speed hunting state. When the throttle opening is fully closed ■, the vehicle speed decreases, and when the throttle opening is fully closed and a small opening ■, the vehicle speed increases, and hunting occurs as shown in the figure. Note that LL indicates a fully closed signal switch.

The region in which constant speed driving is not possible in Figure 3 occurs even when the driver is not careful; when the accelerator is released, the vehicle speed drops below the desired value, and when the accelerator is slightly pressed, the vehicle speed rises above the desired value, and the driver then releases the accelerator or slightly lowers the vehicle speed. The vehicle runs while stepping on the pedals and hunting the vehicle speed. However, the driver does not notice the increase or decrease in vehicle speed as a result of his/her own operations. On the other hand, in the case of automatic driving (driving at a constant speed), the driver does not do anything and is forced to stop frequently, so the shock (hunting) caused by the increase or decrease in vehicle speed is quite noticeable.

The present invention aims to improve these points and enable hunting-free running.

Hunting occurs when the vehicle speed is between the speed at which constant speed travel is desired or when constant speed travel is impossible, and the constant speed travel device opens and closes the throttle in an attempt to keep the vehicle speed constant. Therefore, when driving downhill where you cannot drive unless the throttle opening is close to fully closed, the throttle opening is fixed, sacrificing the accuracy of constant speed driving to some extent to prevent hunting, and the throttle opening is fixed. Area where the degree is far from fully closed (
When the vehicle returns to driving in the vehicle speed range (in which the vehicle can travel), it is sufficient to return to the original throttle opening control. The present invention focuses on this point.

Means for Solving Problem C] As shown in FIG.
A constant speed traveling device 20 consisting of 6 is provided with a throttle opening fully closed traveling region determining means 24, and this means 24 fixes the throttle opening when hunting occurs.

18 is a vehicle, and 22 is a vehicle speed signal processing device. 14a is a comparator, and 14b is an output determining means.

[Effect]

The ratio/calibrator 14a of the comparison output means 14 compares the actual vehicle speed processed by the processing device 22 and the target vehicle speed, and outputs the difference ΔV. The output determining means 14b receives the difference Δ■, determines the duty required to make it zero, and supplies a rectangular wave pulse of that duty to the actuator 16 of the throttle valve. As a result, the vehicle 18 increases or decreases its speed and approaches the target vehicle speed.

The determining means 24 produces an output when it determines that hunting has occurred, and fixes the duty output by the output determining means 14b. This prevents vehicle speed hunting.

FIG. 5 (bl is a diagram explaining the details of this invention. When the vehicle speed increases as it enters a downhill slope, the throttle opening is reduced.
At this point, the engine is at full throttle and the vehicle speed begins to decrease. When the throttle opening is fully opened, the switch LL closes. Therefore, if the duty is fixed to the value at that time as soon as the switch LL is closed, the vehicle speed will decrease as shown by the dotted line, and if the duty is fixed to the value at that time immediately when the switch/7ch LL opens as the vehicle speed decreases. Although the vehicle speed increases as shown by the solid line, it remains within the predetermined value shown in Figure 3, and hunting does not occur.

In either case, the vehicle speed decreases when the downhill slope ends and the vehicle emerges on a flat road. When this decrease is detected, the duty is released from fixation, and the output of the comparator 14a is responded to, the vehicle returns to a constant speed running state.

〔Example〕

FIG. 2 shows an embodiment of the present invention. The throttle/7-torque opening fully closed driving range determining means 24 includes a vehicle speed differentiator 24a, a reference value setter 24b, a comparator 24c, a circuit 24d for detecting when the switch LL is turned from on to off, and a flip-flop circuit. Consists of 24e.

Further, a circuit that keeps the duty output by the output determining means 14b constant includes the memory 14 (i and the switches 81 to S3).
Consisting of

The duty during constant speed driving is the basic duty setting device 14c.
It is determined by adding a correction duty according to the differential speed output from the comparator 14a to the basic duty output by the adder 14e. Always switch 31. S2 off, S
3 off, the output of adder 14e is applied to the actuator and also stored in memory 14d. When the throttle valve fully closed signal switch 24d is turned on and then turned off (
In FIG. 5 (in state bl a), the flip-flop 248 is turned on and the Q output becomes H level. This Q
The output opens switch St, S2 and closes S3, so the duty supplied to actuator 16 is memory 1.
The adder 14e just before opening/closing the switch stored in the adder 14d.
The actuator 16 receives this constant-duty rectangular wave, and in this example puts the throttle valve in a slightly closed state rather than fully closed.

When the switch LL is turned on and the flip-flop 24e is turned on, the duty is fixed to that when the throttle opening is fully closed. Fully opening the throttle while driving at a constant speed can be considered a downhill slope. There are other times when I hit the brakes,
At this time, the constant speed running state is canceled. Further, when accelerating by stepping on the accelerator, then releasing the accelerator and pressing the set switch, the engine can be fully opened, but in this case, control is inhibited by the Sera 1 temporary timer (for example, for 24 seconds). In addition, full closure may occur during override, that is, when you step on the accelerator while driving at a constant speed, then release the accelerator to return to constant speed driving, but in this case as well, control is prohibited (for example, within a range of 7 km or more from the target speed). It has become. Therefore, if a fully closed state is detected while traveling at a constant speed, it is generally assumed that the vehicle has entered a speed range in which constant speed travel is not possible, and hunting can be prevented by fixing the duty at the fully closed state.

As the vehicle speed decreases when it reaches a flat road after going downhill, this is detected by the differentiator 24a, and when it exceeds the reference value, the comparator 2
4c, which causes flip-flop 2
4e, the switch S1. S2 is on, S
3 is turned off and returns to the original constant speed driving.

The determining means 24 can be configured by software. For example, if the status of switch LL is taken in and it is turned off, which was previously on, switches SI to S3 are opened and closed.
"Produces an output, and also sets the reference value 24b, for example, deceleration 2.
．． 5 Km/h/s is used as a window, and when the deceleration determined from the vehicle speed exceeds the reference value by, for example, 3.0 Km/h/s, the above-mentioned "1" output may be changed to "0" output.

〔Effect of the invention〕

As explained above, according to the present invention, vehicle speed hunting that occurs on a downhill slope can be avoided by simple means, and is extremely effective.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic form of the present invention, Fig. 2 is a block diagram showing an embodiment of the invention, Fig. 3 is an explanatory diagram of the region where constant speed driving is impossible, and Fig. 4 is a diagram showing the fuel cut/on state. The explanatory diagram, FIG. 5, is an explanatory diagram of the running state. 1 and 2, 10 is an actual vehicle speed detector, 12 is a target vehicle speed setter, 14a is a comparator, 14 is a comparison output means, 16 is an actuator, 24 is a throttle opening fully closed driving range determining means, 14d is a memory, and 31 to S3 are switches. Applicant Fujitsu Ten Co., Ltd. Representative Patent Attorney Minoru Aoyagi Figure 1 Figure 2

Claims (3)

[Claims] (1) Comparison output means (14) that generates an output having a duty to make the difference zero according to the difference between the actual vehicle speed and the target vehicle speed; In a constant speed running device for a vehicle having an actuator that opens and closes, a means (24) for determining a fully closed throttle opening range is provided,
Further, when the discrimination means (24) produces an output, means (14d, S_1 to S_3) are provided for fixing the duty output by the comparison output means to the value at the time when the output is produced. Speed running device. (2) The constant speed throttle opening fully closed driving range determining means generates an output when the throttle opening changes from fully closed to open in a constant speed driving state. Traveling device. (3) The constant speed traveling device according to claim 1, wherein the throttle opening fully closed traveling region determining means produces an output when the throttle opening is fully closed in a constant speed traveling state. .