JPS6299221A - Constant speed running device for automobile - Google Patents

Abstract

PURPOSE:To prevent a vehicle from hunting, by providing such an arrangement that the vehicle is shifted up after a first set time elapses when the vehicle speed exceeds a set vehicle speed by a predetermined value during the vehicle running on a slope, and the vehicle is shifted up after a second set time elapses when the vehicle speed comes to be below a predetermined value. CONSTITUTION:When an actual vehicle speed VA exceeds a set vehicle speed VS which is set by turning on a set switch 16, by a predetermined value DELTAV, a control device 11 delivers a signal to an automatic speed change gear 21 after a time DELTAt1 elapsed so that a vehicle is shifted down to the third speed stage. Further, when the vehicle speed VA is less than VS+DELTAV due to the shift- down, the vehicle is shifted up from the third speed stage to the fourth speed stage. In this case, the control device 11 computes a vehicles speed variation rate dVA/dt just before the shift-down or the shift-up, and therefore, the first set time DELTAt1 is shortened in accordance with the thus computed variation rate while the second set time DELTAt2 is set to be long. With this arrangement, it is possible to prevent the vehicle from hunting during the shift-up or the shift- down.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a constant speed traveling device for an automobile, and more particularly, to a method for shifting an automatic transmission to maintain constant speed traveling in a desired state on a downhill slope. The present invention relates to a constant speed traveling device for an automobile that can suitably perform down/upshift control.

(Prior art) In a conventional automatic transmission vehicle equipped with a constant speed traveling device that controls the speed so that the vehicle travels at a constant speed at a set speed, while driving at a constant speed in the overdrive range, it is difficult to Engine braking may not be as effective on hills, and the vehicle speed may increase significantly above the set vehicle speed. Therefore, in the constant speed traveling device for vehicles disclosed in Japanese Patent Application Laid-Open No. 59-126142, when a vehicle equipped with an automatic transmission with overdrive is running at a constant speed in the overdrive range, the engine If the brakes are not effective and the vehicle speed increases by more than a predetermined value than the set vehicle speed value, it will shift down from the overdrive range, so even if you are driving at a constant speed and approach a steep downhill slope, the system will automatically shift down. This allows the engine to downshift to improve the effectiveness of engine braking and suppress vehicle speed increases.

(Problems to be Solved by the Invention) However, in the constant speed traveling device configured as described above, when the vehicle speed is near a predetermined value greater than or equal to the set vehicle speed value, or when the downhill slope is long, , there is a problem in that downshifts and upshifts occur successively, resulting in hunting.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a constant speed driving device for an automobile that can prevent hunting during downshifting and upshifting of an automatic transmission even when the automobile is traveling at a constant speed downhill. It is something to do.

(Means for Solving the Problem) As shown in FIG. 1, the constant speed traveling device for a motor vehicle of the present invention includes a shift switching means for shifting up and downshifting the gear stage of an automatic transmission a of a motor vehicle. A fuel supply control means d that controls the amount of fuel supplied to the engine C, a vehicle speed detection means e that detects the vehicle speed, and controls the fuel supply control means to maintain the vehicle speed at a set vehicle speed f, and also controls the fuel supply control means to maintain the vehicle speed at a set vehicle speed f. When the vehicle speed detected by the vehicle speed detecting means increases by a predetermined value or more than the set vehicle speed, the shift switching means is operated to downshift after a first set time, and the vehicle speed is changed to the set vehicle speed. control means g that operates the shift switching means to shift up after a second set time when the vehicle speed returns to a predetermined value or less; and a control means g that operates the shift switching means to shift up after a second set time; vehicle speed change rate calculation means for calculating the vehicle speed change rate immediately before the vehicle speed returns to a speed equal to or lower than the predetermined value added to the set vehicle speed; The present invention is characterized by comprising a time setting means i for setting the first and second set times. It is preferable that the time setting means sets the first set time short and the second set time long, depending on the magnitude of the vehicle speed change rate.

(Operations and Effects of the Invention) In the constant speed traveling device for a motor vehicle of the present invention configured as described above, when the vehicle speed becomes a predetermined speed or more than the set vehicle speed on a downhill slope while traveling at a constant speed, the first setting When the speed is shifted down after a certain period of time and the speed returns to the predetermined speed, the automatic transmission is shifted up after the second set time.
can prevent pinching. Further, in the present invention, when the rate of change in vehicle speed is large, that is, when the vehicle is traveling on a steep slope, the first set time is shortened and the second set time is lengthened, so that the vehicle speed is controlled. The amount of overshoot can be kept small.

(Example) Hereinafter, a constant speed traveling device for an automobile according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

(Example) A constant speed traveling device for an automobile according to a preferred embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, the constant speed traveling device includes a control device 11 connected via a main switch 14 to a power supply circuit 13 led from a power source 10 via an ignition switch 12. This control device 11 is composed of a microcomputer, and includes a central processing unit (CPU) that performs various calculations, a fixed storage unit (ROM) that contains control programs shown in the flowcharts described later, and a random storage unit that temporarily stores various data. Access memo IJ (RA
M). This control device 11 receives signals from a set switch 16, coast switch 17, and resume switch 18 as vehicle speed setting means, and a signal from a vehicle speed sensor 19 that detects vehicle speed.
Further, the control device 11 outputs a signal to a fuel supply device 20 and an automatic transmission 21 that control the supply of fuel to the engine.

The set switch 16, the coast switch 17, and the resume switch 18 are connected between the control device 11 and the ground. Among these switches, the set switch 16 is connected when the vehicle speed indicated by the signal from the vehicle speed sensor 7 is, for example, When the vehicle speed is within the range of 40~1001<m/h, turn it on when the desired vehicle speed is reached.
The vehicle speed at that time is set as the set vehicle speed for constant speed driving. Further, the coast switch 17 is used to decelerate the vehicle while traveling at a constant speed, and the vehicle speed decreases when it is turned on. Furthermore, when the constant speed running control is canceled due to a reason other than the OFF operation of the main switch 14, turning the resume switch 18 ON returns the vehicle to the set vehicle speed before the cancellation. and,
Based on the operation of these switches 16, 17, and 18 and the signal from the vehicle speed sensor 19, the control device 11 sends solenoids 23a, 2, 3b, and 23c of the actuator 23 of the engine fuel supply control device 22 to maintain the vehicle speed. , a signal is output to decelerate or restore the speed. Further, when traveling at a constant speed and on a downhill slope, if the vehicle speed increases by a predetermined value or more from the output of the vehicle speed sensor 7, a shift down signal Sd is output to the automatic transmission 21 as described later.

Next, the structure of the actuator 23 will be explained. As shown in FIG. 3, the actuator 23 is a negative pressure diaphragm type actuator, and the inside of the casing 26 is made airtight from the outside by a rubber diaphragm 27. The negative pressure chamber 28 is divided into a negative pressure chamber 28 and an atmospheric chamber 30 communicated with the outside through a through hole 29, and the diaphragm 27 is biased toward the atmospheric chamber 30 by a spring 31 disposed within the negative pressure chamber 28. At the same time, a negative pressure introduction solenoid valve 51 for controlling the introduction of negative pressure into the negative pressure chamber 28 and first and second atmosphere introduction solenoid valves 52 and 53 (second atmosphere introduction solenoid valves) are provided on the end face of the casing 26. The configuration includes a valve 53 (not shown). A rod 32 connected to the diaphragm 27 is slidably held by a bearing 33 provided on the casing 26 and protrudes outward through the atmospheric chamber 30. The throttle valve 35 is connected to a throttle valve 35 provided in an intake passage of the engine, and the throttle valve 35 is operated in the opening direction when the diaphragm 27 moves in the A direction (towards the negative pressure chamber 28).

Further, the negative pressure introduction solenoid valve 51 opens a passage 51b, which has one end connected to the negative pressure introduction pipe 36 led from the negative pressure source and the other end communicated with the negative pressure chamber 28, with the valve body 51c. The valve body 51c is pressed and biased by a spring 51d to shut off the passage 51b, and also opens the passage 51b against the spring 51d when the solenoid 23a is energized. will be moved to Similarly, the first atmosphere introduction solenoid valve 52 (the same applies to the second atmosphere introduction solenoid valve 53) has one end opened to the atmosphere and the other end connected to the passage 52b communicating with the inside of the negative pressure chamber 28. The valve body 52c is configured to open and close the passage by a spring 52d.
The solenoid 23b is tension-biased to open the passage 52b, and blocks the passage 52b against the spring 52d when the solenoid 23b is energized. The solenoids 23a, 23b, and 23C in these solenoid valves 51, 52, and 53 are energized and controlled by signals from the control device 11 shown in FIG. is controlled, and the opening degree of the throttle valve 35 is controlled by displacing the diaphragm 27 in accordance with this negative pressure.

Next, the specific operation of the above embodiment will be explained.

During normal driving, the vehicle speed is, for example, 40 to 1100 km/h.
When the set switch 16 connected to the control device 11 of the constant speed traveling device is turned on when the vehicle speed is within the range of h, the vehicle speed at that time indicated by the signal from the vehicle speed sensor 19 becomes the set vehicle speed.
5 is set in the RAM of the control device 11, and thereafter, while comparing this set vehicle speed and the actual vehicle speed indicated by the signal from the vehicle speed sensor 19, the actual vehicle speed is set to the set vehicle speed. A signal is output from the control device 11 to the actuator 23 to make them match.

In other words, the actual vehicle speed ■. When the vehicle speed is lower than the set vehicle speed■5,
A solenoid valve 51 for introducing negative pressure from the control device 11 to the actuator 23 and a solenoid valve 5 for introducing the first atmosphere
An energization signal is output to the second solenoids 23a and 23b, the negative pressure introduction solenoid valve 51 opens, and the first atmosphere introduction solenoid valve 52 closes. Therefore, negative pressure is introduced into the negative pressure chamber 28 of the actuator 23 and the diaphragm 27
is displaced in the A direction, and along with this, the rod 32
The throttle valve 35 is operated in the opening direction via the wire 34. As a result, the actual vehicle speed increases and becomes equal to the set vehicle speed. On the other hand, when the actual vehicle speed ■^ is higher than the set vehicle speed ■s, the solenoids 23a and 23b are not energized, so that the negative pressure introduction solenoid valve 51 is closed and the first atmosphere introduction solenoid valve 52 is closed.
opens, so that the negative pressure in the negative pressure chamber 28 is reduced. Therefore, the diaphragm 27 is displaced in the direction opposite to A, and the throttle valve 35 is operated in the closing direction, thereby reducing the actual vehicle speed to match the set vehicle speed. In addition, during such constant speed traveling control, the solenoid 23C of the second atmosphere introduction solenoid valve 53 is always energized.
The valve 53 is kept closed. Furthermore, when the clutch switch 24 or the brake switch 25, which serves as a means for canceling the constant speed running control, is turned on, the energization to the solenoids 23a, 23b, and 23C is all stopped, and the negative pressure introduction solenoid valve 51 is closed. , and the first and second atmosphere introduction solenoid valves 52 and 53 are opened to open the negative pressure chamber 28 to the atmosphere, so that the operation of the actuator 23 is completely stopped, and the throttle valve 35 of the engine is opened when the accelerator pedal is pressed. It will be activated by operation.

Here, when the vehicle is traveling at a constant speed, it may not be possible to maintain the constant speed traveling state only by adjusting the opening degree of the throttle valve 35 as described above. For example, when traveling down a long downhill slope, the actual vehicle speed VA will significantly exceed the set vehicle speed (2) if the vehicle remains in fourth gear, which is the gear during constant speed travel.

Therefore, in the present invention, as shown in FIG. 4, when the actual vehicle speed ■ exceeds the set vehicle speed ■5 by more than a predetermined value △■, the control device W11 operates to shift the speed from 4th gear after △t1 hours. When the actual vehicle speed ■4 becomes smaller than Vs + △■ due to the downshift, the driver shifts from the 3rd gear to the 4th gear after Δt2 hours to maintain constant speed driving. is maintained, and due to the effects of △ti and △t2 mentioned above, the 4th and 3rd speed
This prevents hunting between the speed and the speed. Furthermore, in the present invention, in the control circuit 11, ■, ■5 fixed time Δt is set short, and second set time Δt2 is set long, so that about 5 seconds of control It is desirable to set it to .

Next, details of the vehicle speed control will be explained with reference to the flowchart shown in FIG. In addition, in this control, Vs +△■ is again changed to ■.

Let's proceed with the story as follows. In addition, in the following explanation, “SF
” indicates a shift flag; when 5F=1, it indicates third speed, and when 5F=O, it indicates overdrive (fourth speed).

When constant speed driving is started, shift flag SF is first set to 0, and constant speed driving control is performed.

After this, is there any speed deviation, i.e. ■E -■?

It is determined whether ≧0 or not, and if this determination is No, it is determined whether the current speed is 4th speed. When this judgment is YES,
Returning to the step of constant speed running control described above.

If the above ■Eh-■, ≧0 judgment is YES, 5F
If the determination is YES, the process returns to the constant speed running control step.

If the above judgment of V A V s ≧0 is YES, 5
When the determination of F=1 is NO, it means that you are driving in 4th gear and have exceeded ■, or ■ for the first time.In this case, first calculate the vehicle speed change rate, and then calculate the vehicle speed change rate based on this change rate. Based on the set Δt1, the timer is started and the set Δ1. After seconds have elapsed, the gear is shifted down from the fourth gear to the third gear, the SF is set to "1", and the process returns to the constant speed running control step.

On the other hand, if the above determination of V −V s ≧0 is No, 5F
When the determination of whether = 0 is NO, you are driving in 4th gear and ■ becomes larger than Vs, so you shift down to 3rd gear, and only after that downshift do ■ become smaller. At this time, calculate the vehicle speed change rate, then set △t2 based on this change rate, start the timer operation, and shift from 3rd to 4th speed after △t2 seconds have passed. Then, the SF is set to 0, and the process returns to the constant speed running control step.

As explained above, according to the present invention, when downshifting or upshifting while driving at a constant speed, these shift changes are performed after a preset time based on the vehicle speed change rate after predetermined setting conditions are satisfied. Therefore, it is possible to prevent gear change hunting on long downhill slopes, etc., and to suppress control overshoot l to a small value.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a constant speed traveling device according to the present invention, FIG. 2 is a block diagram showing main parts of a constant speed traveling device according to an embodiment of the present invention, and FIG. 3 is a diagram showing the main parts of a constant speed traveling device according to an embodiment of the present invention. FIG. 4 is a sectional view showing the configuration of the actuator; FIG. 4 is a time chart illustrating an example of the constant speed cruise control of the present invention; FIG. 5 is a flowchart illustrating an example of the constant speed cruise control of the present invention. a...Automatic transmission, b...Shift switching means, C...Engine, d...Fuel supply control means, e... Vehicle speed detection means, g...
...control child actor, h...vehicle speed change rate calculation means, 1
...Time setting means. Party 4 diagram lIAL2 Party 2 diagram

Claims (2)

[Claims] (1) Shift switching means for shifting up and downshifting the gear stage of the automatic transmission of the automobile, fuel supply control means for controlling the amount of fuel supplied to the engine, vehicle speed detection means for detecting the vehicle speed, and setting the vehicle speed. The fuel supply control means is controlled to maintain the vehicle speed, and when traveling downhill,
When the vehicle speed detected by the vehicle speed detection means increases by a predetermined value or more than the set vehicle speed, after a first set time,
When the shift switching means is operated to downshift and the vehicle speed returns to a vehicle speed equal to or less than the set vehicle speed plus the predetermined value, the shift switching means is operated to shift up after a second set time. means, and vehicle speed change rate calculation means for calculating the vehicle speed change rate immediately before the time when the vehicle speed increases by a predetermined value or more from the set vehicle speed and the time when the vehicle speed returns to a vehicle speed equal to or less than the set vehicle speed plus the predetermined value, respectively; A constant speed traveling device for a motor vehicle, comprising: time setting means for setting the first and second set times according to the vehicle speed change rate calculated by the vehicle speed change rate calculation means. (2) The time setting means is configured to set the first set time short and set the second set time long depending on the magnitude of the vehicle speed change rate. A constant speed running device for an automobile as described in 2.