JPS62163834A - Constant-speed running gear for automobile - Google Patents

Abstract

PURPOSE:To prevent driving comfortableness from dropping, by controlling a control gain of constant-speed control so as to be lowered to some extent at a time when a fuel cut is detected during constant-speed running, while holding down a variation range of car speed to be produced with the fuel cut to be lowish. CONSTITUTION:A constant-speed running gear is provided with a controller which makes a running speed to be detected by a running speed sensor 9 when an accelerator switch (set switch) 6 is turned on, settable as the setting running speed at the time of constant-speed running, and controls solenoids 11a-13a of an actuator 10 whereby it performs maintenance of the speed, acceleration and deleration or resetting. In this case, a fuel cut detecting device 30 is connected to the controller 5, and when a cut of fuel supply to an engine is detected by this device 30, a control gain of constant-speed running control is made so as to be lowered as fa as a portion for the specified time (for example, one minute) since he fuel supply cut has been started. With this constitution, adjustment for a running speed variation with on and off operations of the fuel cut is slowly performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a constant speed traveling device for an automobile that maintains the vehicle speed at a desired set value and causes the vehicle to travel at a constant speed.

(Prior Art) In recent years, constant speed traveling devices that automatically maintain the vehicle speed of an automobile at a desired speed set by a driver have been put into practical use. This constant speed traveling device sets the vehicle speed as a target value for constant speed traveling by a set operation by the driver when the vehicle speed reaches a desired vehicle speed, and thereafter compares this set vehicle speed with the actual vehicle speed. Therefore, when a difference occurs between the two, the throttle valve of the engine is controlled according to the difference, thereby making the actual vehicle speed match the set vehicle speed. An example of such a constant speed traveling device is disclosed in Japanese Utility Model Application No. 57-164228.

If such a constant speed traveling device is used to perform constant speed traveling, it is possible to perform constant speed traveling not only on flat roads but also on uphill and downhill roads. In this case, when driving downhill, the increase in vehicle speed that occurs when driving downhill is suppressed by reducing the opening of the throttle valve to maintain constant speed driving, but the slope of the slope If this increases and the opening of the throttle valve becomes smaller, the fuel supply to the engine is often cut. When this fuel supply is cut, the engine braking effect increases and deceleration occurs, but the deceleration at this time is often quite rapid, and as a result, the vehicle speed may be decelerated beyond the set value. easy to become. When the vehicle speed is decelerated beyond the set value, the throttle opening is increased again and the speed is increased. At this time, if the vehicle is still traveling on the exit road, the vehicle speed increases again beyond the set value. Therefore, the fuel supply will be cut again. In this way, when driving at a constant speed on a descending road, the fuel supply cut is repeatedly turned on and off in order to maintain constant speed driving.
The vehicle runs at a constant speed while periodically fluctuating around the set value. This kind of fuel supply cut 1 to 0N-OFF is as follows:
For example, if a car is running on a 5% downhill slope at 50 to 60 KJ#/H, this happens about once every 5 seconds. If such fluctuations in vehicle speed occur due to 0N-OFF of the fuel cut, this will lead to a decrease in ride comfort, so the vehicle speed fluctuations should be kept as small as possible and the cycle of vehicle speed fluctuations should be made as long as possible to improve ride comfort. It is desirable to improve the

(Objective of the Invention) In view of the above circumstances, the present invention is designed to minimize vehicle speed fluctuations caused by fuel supply cut when driving at a constant speed on a descending road, and to lengthen the cycle of this vehicle speed fluctuation as much as possible. The object of the present invention is to provide a constant-speed traveling device for a motor vehicle.

(Configuration of the Invention) The configuration of the constant speed traveling device for an automobile of the present invention will be explained based on the block diagram of FIG. 3.

This constant speed traveling device compares the actual vehicle speed detected by the first speed detection means B1 with the set vehicle speed in the vehicle speed control means B2, and outputs an operating signal from the vehicle speed control means B2 to the fuel supply means B3 to open/close the throttle valve, etc. The fuel supply amount to the engine is controlled by controlling the amount of fuel supplied to the engine so that the actual vehicle speed approaches the set vehicle speed, and on the other hand, the presence or absence of a cut in the fuel supply to the engine is detected by the fuel cut detection means B4, When the detection means B4 detects that the fuel supply has been cut, the control gain adjustment means B5 operates, and the vehicle speed control means B2 operates until a predetermined time elapses from the time of this detection.
This feature is characterized in that the gain of the constant speed running control is reduced.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the constant speed traveling device has a controller 5 connected via a main switch 4 to a power supply circuit 3 led from a power source 1 via an ignition switch 2. Signals from the accelerator switch 6, coast switch 7, and resume switch 8 as setting means and signals from the vehicle speed sensor 9 are input, and signals are output from the controller 5 to the solenoids 11a, 12a, and 13a of the actuator 10. It has become so. Here, the controller 5 plays a role as a vehicle speed control means, is composed of a microcomputer, and includes various arithmetic processing units (CPU).
, read-only memory (ROM) containing control programs
) e and various data are temporarily stored in the layered memory (
RAM).

The accelerator switch 6, the coast switch 7, and the resume switch 8 are connected between the controller 5 and the ground. Among these switches, the accelerator switch 6 also functions as a set switch, and is connected to the vehicle speed sensor 9. For example, if the vehicle speed indicated by the signal is 40~
A vehicle speed setting function that sets the vehicle speed at that time as the set vehicle speed for constant speed driving by turning ON when the desired vehicle speed is reached when the vehicle speed is within the range of 100/h.
By maintaining the N state, the set vehicle speed is increased during this time, and when the vehicle is turned off, it has an acceleration function that causes the vehicle to travel at a constant speed at this increased vehicle speed. Further, the coast switch 7 is used to decelerate the vehicle while traveling at a constant speed, and when it is turned on, the set vehicle speed decreases. Further, when the constant speed driving control is canceled due to a reason other than the OFF operation of the main switch 4, the resume switch 8 is turned ON to return the vehicle to the set vehicle speed before the cancellation. Then, the solenoid 11a of the actuator 10 is activated from the controller 5 based on the signals from the operation of these switches 6, 7, and 8 and the signal from the heavy speed sensor 9.

Maintain the vehicle speed at 12a and 13a, accelerate, decelerate,
Alternatively, an activation signal is output so as to cause the device to return to its original state.

Further, in this constant speed traveling device, a clutch switch 14 as a constant speed traveling canceling means for canceling constant speed traveling control and a brake switch 15 are arranged in parallel between the power supply circuit 3 and the controller 5. These switches 14 and 15 are turned ON when the clutch is disengaged and when the brake is applied, respectively, to input a release signal to the controller 5 and cause the controller 5 to release the constant speed running control.

The controller 5 also includes fuel cut detection means 3 for detecting that the fuel supply to the engine has been cut.
0 is also connected, and when the fuel supply is cut, this means 30 sends a signal notifying the controller 5 of the fuel cut. Upon receiving a signal that this fuel supply cut has been made,
The controller 5 acts as a control gain adjustment means, and maintains the control gain for a predetermined period of time (for example, 1 minute) after the start of cutting the fuel supply.
The control gain is reduced by

By doing this, the fuel supply cut is 0N-
Vehicle speed fluctuations caused by turning off the vehicle are adjusted slowly, the width of the vehicle speed fluctuations is made small, and the cycle is lengthened, thereby preventing a decrease in ride comfort caused by vehicle speed fluctuations.

Next, to explain the structure of the actuator 10, as shown in FIG. 2, the actuator 10 is a negative pressure diaphragm type actuator, and the inside of the casing 16 is airtight from the outside by a rubber diaphragm 17. The diaphragm 17
a negative pressure introduction solenoid valve 11 that urges the air pressure toward the atmospheric chamber 20 by a spring 21 disposed within the negative pressure v18, and controls the introduction of negative pressure into the negative pressure chamber 18 on the end face of the casing 16; 1st. Second atmosphere introduction solenoid valve 12.13 (Second atmosphere introduction solenoid valve 1
3 (not shown).

A rod 22 connected to the diaphragm 11
is slidably held by a bearing part 23 provided in the casing 16 and projects outward through the atmospheric chamber 20, and is provided in the intake passage of the engine via a wire 24. It is connected to the throttle valve 25 and operates the throttle valve 25 in the opening direction when the diaphragm 17 moves in the A direction (toward the negative pressure chamber 18 side).

Further, the negative pressure introduction solenoid valve 11 opens a passage 11b, which has one end connected to a negative pressure introduction vibe 26 guided from a negative pressure source and the other end communicated with the negative pressure seedling 18, with a valve body 11C. The valve body 11c is biased by a spring 11d to close the passage 11b, and is configured to open the passage 11bf against the spring 11d when the solenoid 11a is energized. will be moved. Similarly, the first atmosphere introduction solenoid valve 12 (the same applies to the second atmosphere introduction solenoid valve 13) has a passage 12b, which has one end open to the atmosphere and the other end communicated with the negative pressure v18, connected to the valve body 12c. The valve body 12c is configured to open and close the passage 1 by means of a spring 12d.
2b is tensilely biased to open,
When the solenoid 12a is energized, the passage 12b is blocked against the spring 12d. and,
The negative pressure in the negative pressure chamber 18 of the actuator 10 is controlled by energizing the solenoids 11a, 12a, and 13a of these solenoid valves 11, 12, and 13 using signals from the controller 5 shown in FIG. At the same time, the diaphragm 17
The opening degree of the throttle valve 25 is controlled by the displacement of the throttle valve 25.

Next, the concrete operation of the above-mentioned actuator will be explained.

During normal driving, the vehicle speed is, for example, 40 to 1001 m/
When the accelerator switch 6 connected to the control device 5 of the constant speed traveling device is turned on while the vehicle is within the range of H, the current vehicle speed indicated by the signal from the vehicle speed sensor 9 is set in the controller 5 as the set vehicle speed. Thereafter, a signal is output from the controller 5 to the actuator 10 to match the actual vehicle speed with the set vehicle speed while comparing the set vehicle speed with the actual vehicle speed indicated by the signal from the vehicle speed sensor 9.

That is, when the actual vehicle speed becomes lower than the set vehicle speed, an energization signal is output from the controller 5 to the solenoid Ha and 12a of the negative pressure introduction solenoid valve 11 and the popular introduction solenoid valve 12 in the actuator 10, and the negative pressure introduction solenoid valve 11 opens, and the first atmosphere introduction solenoid valve 12 closes. Therefore, negative pressure is introduced into the negative pressure chamber 18 of the actuator 10, and the diaphragm 17 is displaced in the backward direction.Accompanyingly, the throttle valve 25 is operated in the opening direction via the rod 22 and the wire 24, and the engine is The amount of fuel supplied will increase. As a result, the actual weight speed increases by 1 and becomes equal to the set vehicle speed. On the other hand, when the actual vehicle speed is higher than the set vehicle speed, the solenoid 11
By not energizing a and 12a, the negative pressure introduction solenoid valve 11 is closed and the first atmosphere introduction solenoid valve 12 is opened, so that the negative pressure in the negative pressure chamber 18 is reduced. Therefore, the diaphragm 17 is displaced in the opposite direction, the throttle valve 25 is operated in the closing direction, and the amount of fuel supplied to the engine is reduced, thereby reducing the actual vehicle speed to match the set vehicle speed. In addition, during such constant speed running control, the solenoid 13a of the second atmosphere introduction solenoid valve 13 is constantly energized, and the valve 13 is maintained in a closed state. Furthermore, when the clutch switch 14 or the brake switch 15, which serves as a means for canceling the constant speed running control, is turned on, each of the solenoids 1 and 15 is turned on.
All power to 1a, 12a, and 13a is stopped,
The negative pressure introducing solenoid valve 11 is closed, and the first solenoid valve 11 is closed. The second atmospheric air introduction solenoid valve 12.13 is activated and the inside of the negative pressure chamber 18 is released to the atmosphere, so that the operation of the actuator 10 is completely stopped, and the throttle valve 25 of the engine
is activated by operating the accelerator pedal.

Note that when the fuel cut detection means detects that the fuel supply to the engine has been cut, the controller 6 is configured to reduce the vehicle speed control gain by a predetermined period of time.
During this time, the opening speed of the solenoid valve is controlled to control the speed at which negative pressure is introduced into the negative pressure chamber, and the displacement speed of the diaphragm 17 is adjusted. The opening degree of the solenoid valves 11 and 12 is controlled by controlling the duty ratio of the energization of the solenoid or by controlling the amount of movement caused by the energization of the solenoid.

The contents of the controller 5 in the constant speed traveling device described above will be explained with reference to the flowchart of FIG.

In the main υ control that starts from step S1, first in step S2, Kl is read as the value of the control gain G, and then the process proceeds to step S3, where 1 is used to perform constant speed driving control. As mentioned above, this constant speed driving control
Compare the set vehicle speed and the actual vehicle speed, and if the actual vehicle speed is lower than the set vehicle speed, increase the throttle valve opening, and conversely, if the actual vehicle speed is higher than the set vehicle speed, decrease the throttle valve opening. The operation of the actuator is controlled so that the actual vehicle speed approximately matches the set vehicle speed.

When performing such constant speed driving control, step S4
In the step S2, the fuel cut detection means detects whether or not the fuel supply to the engine has been cut, and if the fuel supply has not been cut, the process returns to step S2 to continue the constant speed driving control, while the fuel When it is detected that a supply cut has been made, the value of the control gain G is set to Kz lower than 1 for a predetermined period of time (for example, 1 minute) from the time when this detection is made, and this lowered control gain is 2 to perform constant speed driving control.

Figure 5 shows the changes in vehicle speed when constant speed driving control is performed using such a low control gain. , a case where fuel cut is made at time T1 is shown.

When it is detected that a fuel cut has been made at time T1, the control gain is lowered to 2 for a predetermined period of time,
For this reason, as shown in the figure, the cycle of vehicle speed fluctuations when trying to maintain the vehicle speed at the set value becomes longer and the fluctuation range becomes smaller. In this figure, the solid line indicates the case where the gain is 2, and the broken line indicates the case where the gain is 1.

(Effects of the Invention) As described above, according to the present invention, in a constant speed traveling device that controls the amount of fuel supplied to the engine to perform constant speed traveling, the detection means for detecting a cut in the fuel supply to the engine When a fuel cut is detected while driving at a constant speed, the control gain of the constant speed driving control is reduced, so that the range of fluctuations in vehicle speed caused by the fuel cut can be kept small, and the period of fluctuations in vehicle speed can be reduced. can be made longer to prevent ride comfort from deteriorating due to vehicle speed fluctuations.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a constant speed traveling device according to the present invention, Fig. 2 is a sectional view of an actuator in the device, Fig. 3 is a block diagram showing the configuration of the device, and Fig. 4 is a constant speed driving device by the device. Flowchart showing details of travel control. FIG. 5 is a graph showing changes in vehicle speed when control gains used for control by the device are different. 1...Power supply 4...Main switch 5
... Controller 6 ... Accelerator switch 7
...Coast switch 8...Resume switch 10...Actuator 1γ...Diaphragm 26...Throttle valve 30...Fuel cut detection means Fig. 2 In Fig. 3 Fig. 4 Fig. 51''

Claims (1)

[Claims] A vehicle speed detection means for detecting the actual vehicle speed; a fuel supply means for controlling the amount of fuel supplied to the engine; and a comparison between the actual vehicle speed detected by the vehicle speed detection means and a preset vehicle speed. a vehicle speed control means for controlling the operation of the fuel supply means so that the actual vehicle speed approaches the set vehicle speed and the vehicle runs at a constant speed; and a fuel cut detection means for detecting that the supply of fuel by the fuel supply means has been cut. and when the fuel supply cut detection means detects that the fuel supply has been cut, the gain of the constant speed driving control by the vehicle speed control means is reduced until a predetermined period of time has elapsed from the time of the detection. 1. A constant speed traveling device for an automobile, comprising control gain adjusting means.