JPS60135334A - Constant speed running device for automobile - Google Patents

Abstract

PURPOSE:To improve the feeling to drive without giving a driver any uncomfortableness by constituting the captioned device such that stop and restart of fuel supply are repeated in an as long cycle as possible when running on a long downward slope. CONSTITUTION:A set switch 23 is pushed to cause an output of an F/V converter 12 to be stored in a memory circuit 14 so that an automobile runs at a constant speed. On a flat road, an electronic control fuel injection system EF1 does not stop the fuel supply. The F/C signal is ''0'' and a changeover switch 16 is set on the side of a first pulse generator circuit 17. On a long downward slope, the fuel supply is stopeed by the EF1. A timing circuit 30 is started by the F/C signal and the changeover switch 16 is set on the side of a second pulse generator circuit 18. In such a manner, the number of repeats of stopping and restarting of fuel supply per unit time can be decreased than a conventional one, whereby the frequency of shocks given to the driver can be also decreased to make the feeling to drive more comfortable.

Description

[Detailed description of the invention] Technical field of invention The present invention relates to a constant speed traveling device for automobiles.

Conventional Filling Techniques and Problems Conventionally, in a system that combines a constant speed driving device for automobiles and an electronically controlled fuel injection device (hereinafter referred to as EFI) that stops fuel injection when the throttle opening is approximately zero, When driving down a long downhill slope during constant speed driving control, fuel injection is stopped and restarted repeatedly at short intervals, resulting in intermittent shocks that make the ride less comfortable.

FIG. 1 is a diagram for explaining this problem, and shows the traveling vehicle speed relative to the set vehicle speed a of constant speed traveling control.

This figure shows an example of a temporal change in a throttle opening degree and a fuel cut signal (hereinafter referred to as an F/C signal) that indicates a period in which fuel injection output from the EFI is stopped as a logic "1". On a long downhill slope, in order to maintain the set vehicle speed a, the throttle opening must be fully closed. When the throttle opening is fully closed, the EFI detects this with the throttle opening sensor and injects fuel. cant only during the fully closed period. Therefore, the speed of the car decreases quickly.

When the traveling vehicle speed reaches a certain value below the set speed, the throttle opening becomes large again, and if the throttle opening becomes almost zero (then the EFI resumes fuel injection).

When this injection is restarted, a shock occurs because a large acceleration is temporarily generated. When injection is restarted and the throttle opening gradually increases, and the traveling vehicle speed reaches a certain value above the set speed, the throttle opening decreases again, and if the target speed cannot be maintained, the throttle opening becomes full. It is closed and fuel injection is also canted. In the conventional constant speed driving system for automobiles, the cycle of fuel cut and restart is very short, for example, about 10 seconds. For this reason, as mentioned above, intermittent shocks are repeated in short cycles, making the ride very uncomfortable.

Purpose of the Invention The present invention improves these conventional drawbacks, and
The purpose of this is to make the cycle of fuel cut and restart as long as possible on long downhill slopes, thereby making the driver feel comfortable and not feeling uncomfortable.

Embodiment of the Invention FIG. 2 is a block diagram of essential parts of an embodiment of the constant speed traveling device for automobiles of the present invention.

In the figure, numeral 10 is a reed switch for detecting the speed of an automobile, and numeral 11 is a permanent magnet driven to rotate by a speedometer cable. The reed switch 10 turns on and off as the permanent magnet 11 rotates, and generates a pulse signal having a frequency proportional to the vehicle speed. This pulse signal is converted into a frequency-voltage conversion circuit (F
/V conversion circuit) 12, it is converted into a DC voltage having a level proportional to the vehicle speed. The output voltage of the F/V conversion circuit 12 is held in the memory circuit 14 when the analog switch 13 is on. The set voltage held in the memory circuit 14 is input to the differential amplifier 15, where the difference between it and the output voltage of the F/V conversion circuit 12, that is, the running vehicle speed is determined. This difference signal is input to either the first pulse generation circuit 17 or the second pulse generation circuit 1 through the changeover switch I6. The changeover switch / switch 16 is a time limit circuit 30
When the output is "o", it is set to the upper side, that is, the first pulse generation circuit 17 side, and when it is 1'', it is set to the lower side, that is, the second six pulse generation circuit 18 side. , when it receives an F/C signal from an EFI (not shown), its output is set to "1" for a certain period of time.

1st. In both of the second pulse generation circuits 17 and 18, when the vehicle speed corresponding voltage is higher than the set voltage, the energization time to the control valve 19 and a of the actuator 19 is shortened, and in the opposite case, the energization time is lengthened. It generates a pulse-like output of "1" and "0" whose duty ratio is controlled so that
The change gains of the duty ratio with respect to the difference between the traveling vehicle speed and the set vehicle speed (referred to as vehicle speed difference) are different from each other. In other words, the first
For example, as shown in FIG. 3, the pulse generating circuit 17 of
When the vehicle speed difference is 2 (lKm, duty ratio θ%, +20K
When m, the duty ratio is 100%, and the duty ratio changes almost linearly during that time.
For example, as shown in FIG. 4, the second pulse generating circuit has a duty ratio of 0% when the vehicle speed difference is 140 km.

When the vehicle speed difference is +40 km, the duty ratio is 100%, and during that time, the duty ratio changes almost linearly.

The actuator 19 includes a control valve 19a and a release valve 19.
b. The opening and closing of the control valve 19a is controlled by the output of the amplifier mark. Then, when energized, boat 19
The atmospheric pressure from the boat 19d is cut off and the negative pressure from the port 19d is introduced into the chamber 19e, and when the electricity is cut off, the negative pressure from the boat 19d is cut off and the atmospheric pressure is introduced from the port 19C into the chamber 19e. to be introduced. The release valve 19b is controlled to open and close by the output of the self-holding circuit 22 via the amplifier 21, and when it is energized, it cuts off the atmospheric pressure from the chamber 19f, and when the energization is cut off, it introduces this atmospheric pressure into the chamber 19e. . As described above, by controlling the pressure in the chamber 19e, the diaphragm 19g moves, thereby moving the load 19h connected to the accelerator link (not shown) in its axial direction, and as a result, the throttle valve opens. The degree is controlled by m.

In addition, the output of the cent switch command and the high-speed limiter circuit 24
An AND circuit 25 is provided which receives the output of the AND circuit 25, and the output of the AND circuit closes the analog switch 13 and pre-centers the self-holding circuit 22. When the self-holding circuit 22 is pre-sent, the AND circuit 26 is opened and the release valve 19b is energized through the amplifier 21, so that travel control becomes possible. High speed limiter circuit 24
For example, when a chime signal indicating that the vehicle speed has reached 100 km or more is received, the AND circuit 5 is closed to prevent the set vehicle speed from being memorized. Further, the cancel switch 弗 is a switch that resets the self-holding circuit 22, and when reset, the self-holding circuit 22 is switched to the amplifier 2I.
Stops energizing through. The resume switch 27 is used to restart the constant speed running control that was interrupted by the cancel switch 27. When this switch is pressed, constant speed control is performed with the originally set vehicle speed as the target value. Note that the low speed limiter circuit 29 is for forcibly resetting the self-holding circuit 22 when the vehicle speed decreases to 30 km or less, for example.

In the above configuration, by pressing the cent switch %, the output of the F/V conversion circuit 12 is stored in the memory circuit 14 via the analog switch 13, and constant speed driving control is performed at this set speed. When driving on a flat road, EFI does not cut fuel, so F/
The C signal is 0'', and the changeover switch 16 is set to the first pulse generation circuit 17 side.Therefore, the so-called gain of constant speed running control is large, and speed control with good responsiveness is executed.On the other hand, When a fuel cant is performed in EF1 due to a long downhill slope, the timer circuit 30 is activated by the F/C signal, and the changeover switch 16 is set to the second pulse generation circuit 18 side.

FIG. 5 shows an example of temporal changes in the traveling vehicle speed, throttle opening, F/C signal, and output of the time limit circuit 30 with respect to the set vehicle speed a when the second pulse generating circuit 8 is selected. be. As shown in the figure, in constant speed control on a long downhill slope, when the traveling vehicle speed becomes a certain value larger than the set vehicle speed a and the throttle opening is controlled to zero, E
Due to fuel being cut by FI, the vehicle speed quickly decreases. This state is similar to the conventional one shown in FIG. However, since the time limit circuit 3O is activated and the second pulse generation circuit 18 is selected at the rising edge of the F/C signal, the gain of the constant speed running control thereafter becomes smaller, and the traveling vehicle speed changes more slowly than before. Also, the time limit circuit 30 is activated every time the F/C signal sent out during this fuel cut changes (0→l).
is retriggered.

Therefore, if the output pulse width of the time limit circuit 3O is set to be slightly larger than the period of the F/C signal, for example, about 60 seconds, the second pulse generating circuit 1B is always activated during long downhill travel.
is selected, the number of repetitions per unit time of restarting the fuel cut can be reduced compared to the conventional one, and the number of shocks is also reduced accordingly, making it possible to improve riding comfort.

Further, the time for selecting the second pulse generating circuit 18 is determined by F/
It is clear that the same effect can be obtained by using a predetermined time determined by the time limit circuit 30 while the C signal is "1" and thereafter. In this case, the timer circuit 30 indicates that the F/C signal is "O"-"
It is sufficient to provide a function that is triggered at 1'' and stops the counter operation during 1''.

As described in detail, according to the present invention, the throttle/nottle valve is controlled by the pulse generating means that generates a pulse signal whose duty ratio is controlled according to the difference between the detected running vehicle speed and the preset set vehicle speed. In the constant speed traveling device for an automobile, the pulse generating means includes a first pulse generating means having a small duty ratio change and a first pulse generating means having a large duty ratio change with respect to a unit change in the difference between the set vehicle speed and the traveling vehicle speed. In addition to providing two pulse generating means with a second pulse generating means, when a signal indicating that fuel injection has been stopped from the electronically controlled fuel injection device is received, the signal is sent for a predetermined period of time, or a signal indicating that fuel injection has been stopped. Since a time limit means is provided for selecting the second pulse generating means for a predetermined period of time during and after the fuel cut, the second pulse generating means is selected on a long downhill slope where a fuel cut is performed.
Since the gain of so-called constant speed running control becomes smaller, the cycle of fuel cut and restart can be shortened, and the number of shocks is reduced, making it possible to improve ride comfort.

In addition, since fuel cut is not normally performed when driving on a flat road, the first pulse generation means is selected, and constant speed driving control with good responsiveness is executed as before. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining conventional problems, FIG. 2 is a block diagram of main parts of an embodiment of the constant speed traveling device for automobiles of the present invention, and FIG. 3 is a characteristic diagram of the pulse generation circuit 17. FIG. 4 is a characteristic diagram of the pulse generation circuit 18, and FIG. 5 shows the traveling vehicle speed relative to the set vehicle speed a when the second pulse generation circuit I8 is selected.
FIG. 3 is a diagram showing an example of temporal changes in the throttle opening, the F/C signal, and the output of the time limit circuit 30. FIG. 10 is a reed switch, 12 is an F/V conversion circuit, 13 is an analog switch, 14 is a memory circuit, I5 is a differential amplifier, 16 is a changeover switch, 17.18 is a pulse generation circuit,
19 is an actuator, and 3O is a time circuit. Patent applicant Fujitsu Ten Co., Ltd. Representative patent attorney Tamamushi Gobu and one other person

Claims (1)

[Claims] In a constant speed traveling system for an automobile, the opening of a throttle valve is controlled by a pulse generating means that generates a pulse signal whose duty ratio is controlled according to the difference between a detected traveling vehicle speed and a preset set vehicle speed. As a means, two pulse generating means are provided, a first pulse generating means having a small duty ratio change of the output pulse with respect to a unit change in the difference between the set vehicle speed and the running vehicle speed, and a second pulse generating means having a large duty ratio change, and The second pulse is generated only for a predetermined time when receiving a signal indicating that fuel injection has been stopped from the electronically controlled fuel injection device, or for a predetermined time after receiving a signal indicating that fuel injection has been stopped. A constant speed traveling device for an automobile, characterized in that it is provided with a time limit means for selecting a means.