JPH0425166B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a constant speed traveling device for an automobile.

Conventional technology In general, this type of constant-speed vehicle running system has the following features:
There are two known methods: one that uses a motor actuator that uses a motor as a power source to drive the accelerator link, and the other that uses a negative pressure actuator that uses engine negative pressure (intake manifold negative pressure) as a power source to drive the accelerator link. However, the former is disadvantageous in terms of weight, cost, response, etc.
Modern constant speed driving systems for automobiles exclusively employ the latter method, which does not have such drawbacks.

By the way, in a constant speed vehicle driving system using a negative pressure actuator, the negative pressure inside the actuator is controlled by opening and closing a solenoid valve using a pulse signal having a duty ratio according to the difference between the detected traveling vehicle speed and the stored vehicle speed. At the start of control (when the memorized vehicle speed is set), the pressure inside the actuator is equal to atmospheric pressure. For this reason, when setting, the duty ratio is set to the maximum value (for example, 80 to 90%) for a certain period of time (for example, about 0.5 seconds) immediately after setting, and the vehicle speed is reduced (undershoot) before reaching constant speed driving.
is reduced. Also, when the set switch is turned on during constant speed driving control, the memorized vehicle speed is set to a low value, for example zero, so a so-called coast control that controls the vehicle speed in a direction is executed, and when the set switch is turned off again, when the set switch is turned off. The vehicle speed is set as a new stored vehicle speed and constant speed driving control is started again. If the on time of the set switch during this coast operation exceeds a predetermined time, for example 0.6 seconds, the duty ratio is set to the maximum value for the predetermined time at the start of control, and then normal control is started, and if it is within 0.6 seconds, the duty ratio is set to the maximum value. Normal control is started without setting the value. This is because the negative pressure inside the actuator is not completely released within 0.6 seconds, so if the duty is set to the maximum value for a predetermined period of time, an overshoot phenomenon will occur in which the vehicle speed greatly exceeds the set vehicle speed before the vehicle reaches a constant speed.

However, in the conventional configuration in which the duty ratio is not set to the maximum value unconditionally if the set switch ON time is within a predetermined time (0.6 seconds) when resetting during constant speed driving control, the following occurs. Problems like this arise. That is, as shown in FIG. 4, if a so-called override operation is performed to increase the vehicle speed by operating the accelerator pedal during constant speed driving control at a set vehicle speed, the vehicle speed will become higher than the original memorized vehicle speed. The duty ratio is gradually controlled in a smaller direction, and accordingly, the actuator negative pressure gradually decreases to atmospheric pressure. When the set switch is turned on for a short period of time (within 0.6 seconds) in this state, conventional devices do not increase the duty ratio to its maximum value, but simply perform normal duty ratio control according to the difference between the current vehicle speed and the newly stored vehicle speed. Therefore, it takes a relatively long time Ta for the actuator internal negative pressure to reach a predetermined value (set duty), and a large undershoot occurs in the vehicle speed as shown by Va in the figure.

Problems to be Solved by the Invention The present invention solves these conventional problems, and its purpose is to reduce undershoot at the time of resetting during override.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has provided a negative pressure actuator that uses engine negative pressure as a power source to drive an accelerator link according to the difference between the detected running vehicle speed and the stored vehicle speed. In an automobile constant speed traveling system that is controlled by a pulse signal having a duty ratio, if the memorized vehicle speed is reset in a state where the memorized vehicle speed exceeds a certain vehicle speed width during override, the duty ratio is set to a predetermined value at the start of control. After setting the time to the maximum value, normal duty ratio control is started, and if the memorized vehicle speed is reset in a state where the memorized vehicle speed is less than the certain vehicle speed range, the duty ratio is not increased to the maximum value and normal duty ratio control is started. It is configured to perform ratio control.

Function As shown in Fig. 3a, when the accelerator pedal is depressed while the vehicle is being controlled at a constant speed at a certain memorized vehicle speed, duty ratio, and negative pressure inside the actuator, the vehicle speed gradually increases and the actuator control The pulse duty ratio and the negative pressure inside the actuator gradually decrease. If the set switch is turned on for a short time and then turned off again when the vehicle speed has reached a predetermined vehicle speed width α or more than the original memorized vehicle speed, the duty ratio is set to the maximum value for a predetermined period of time, and then normal duty ratio control is resumed. will be carried out. Therefore, the negative pressure inside the actuator quickly returns to the specified value.
Since the return time Tb is shorter than the conventional return time Ta, the vehicle speed undershoot width Vb can be reduced.

In addition, as shown in Fig. 3b, if the set switch is turned on for a short time and then turned off again while the vehicle speed does not exceed the predetermined width α from the original set vehicle speed, the duty ratio will not be set to the maximum value and will immediately return to normal. duty ratio control is performed. This is because if the vehicle speed does not exceed the predetermined width α, the negative pressure inside the actuator has not been completely released, and the undershoot width will become small even with normal duty ratio control. This is because overshoot will occur. It is desirable that the predetermined width α is set so that it intersects the vehicle speed before the time when the actuator internal negative pressure reaches atmospheric pressure.

Embodiment FIG. 1 is a block diagram showing an example of the hardware configuration of a constant speed traveling device for an automobile according to the present invention.
is a control microcomputer having internal ROM, RAM, etc., 1a, 1b, and 1e are input ports, and 1c and 1d are output ports. The vehicle speed of an automobile is detected by a vehicle speed sensor 2 consisting of a permanent magnet 2a rotated by a speedometer cable and a reed switch 2b placed close to it, and converted into a voltage proportional to the vehicle speed by a frequency-voltage converter 3. This is input to the input port 1a via the A/D converter 9. Further, a set switch 4 is connected to the input port 1b. The set switch 4 is a type of switch that normally maintains the off state, turns on when pressed, and returns to the off state when released. Further, a cancel switch 8 is connected to the input port 1e. This cancel switch 8 is turned on when, for example, the parking brake is activated, the clutch is released, or the brake is stepped on. A pulse with a controlled duty ratio is input from the output port 1c of the microcomputer 1 to the control valve 6a of the negative pressure actuator 6 via the driver 5, and from the output port 1d, the pulse is released via the driver 7. It is input to valve 6b.

When the control valve 6a of the negative pressure actuator 6 is energized, it cuts off the atmospheric pressure from the port 6c and introduces the intake manifold negative pressure from the port 6d into the chamber 6e, and when the energization is cut off, the control valve 6a shuts off the atmospheric pressure from the port 6d. The negative pressure is cut off and atmospheric pressure is introduced into the chamber 6e from the boat 6c. Release valve 6b
is energized during constant speed running control by a signal from the output port 1d via the driver 7, and when energized cuts off the atmospheric pressure from the port 6f, and when the energization is cut off during coasting, this atmospheric pressure is transferred to the chamber 6e. to be introduced. As mentioned above, by controlling the pressure in the chamber 6e,
The diaphragm 6g moves, thereby connecting the rod 6 to an accelerator link (not shown).
h is moved in its axial direction, and as a result, the opening degree of the throttle valve is controlled.

FIG. 2 is a flowchart for explaining the operation of this embodiment, and S1 to S14 indicate each step.
Note that the dotted arrow pointing from step S13 to step S5 indicates the flow of conventional processing, and this embodiment differs in configuration from the conventional processing in that step S14 is added. The operation will be explained below for each case.

[At the start of control]

When constant speed running control is not being performed, the release valve 6b is activated and the negative pressure inside the actuator is equal to atmospheric pressure. At a certain speed, for example 80km/
If you operate set switch 4 while driving at h,
In other words, if you turn set switch 4 on and off,
The microcomputer 1 stores the output of the frequency voltage converter 3 in an internal register A at the timing when the set switch 4 changes from on to off, and stores the vehicle speed Vn-1.
(S3, S9). Since the control flag is "0" at the beginning of the first control, after setting the control flag to "1" (S10, S11), a pulse having the maximum duty ratio is output from the output port 1c for 0.5 seconds ( S12, S6). As a result, the actuator internal negative pressure is rapidly reduced toward the intake manifold negative pressure.

[During normal constant speed driving control]

After outputting the maximum duty ratio pulse for about 0.5 seconds, the microcomputer 1 goes through steps S1 to S4 to step S5, and stores the output of the A/D converter 9 at that time in the internal register B. is taken in as the current vehicle speed, and a duty ratio corresponding to the difference between the contents of register B and register A is calculated. Then, by outputting a pulse having the calculated duty ratio from the output port 1c, control is performed to maintain the vehicle speed at the set vehicle speed of 80 km/h.

[During coast control]

When the set switch 4 is pressed to reduce the vehicle speed by operating the set switch 4, the value stored in the register A is set to zero at the timing when the set switch 4 is turned from off to on. (S1, S2). Therefore, the duty ratio calculated in step S5 becomes a small value, the negative pressure inside the actuator increases in the direction of atmospheric pressure, and the vehicle speed decreases. If you release set switch 4 when the vehicle speed has decreased to a certain extent,
At the timing when the set switch 4 is turned on to off, the output of the A/D converter 9 at that time is set as the new set vehicle speed Vn (S3, S9). Next, since the control flag is "1", it is determined whether or not the ON time of the set switch 4 is 0.6 seconds or more (S13).
If it is above, it is considered that the negative pressure inside the actuator has decreased to near atmospheric pressure, so a pulse with the maximum duty ratio is output from output port 1c for about 0.5 seconds, as at the start of control, and then the normal Executes constant speed control. If the ON time of the set switch 4 does not exceed 0.6 seconds, the process proceeds to step S14. However, in the case of coasting, the original memorized vehicle speed Vn-1 is always greater than the new memorized vehicle speed Vn, so the process proceeds to step S5. Normal constant speed driving control is immediately performed.

[When executing override]

When the accelerator is pressed while the vehicle is under constant speed driving control with 80 km/h stored in register A, the vehicle speed gradually increases as shown in FIG. At this time, since the cruise control device is under control, processing is executed on the path of steps S1 to S8. Since the vehicle speed becomes greater than the memorized vehicle speed, the duty ratio is controlled in a smaller direction, and the negative pressure inside the actuator is also reduced. The pressure gradually approaches atmospheric pressure. When the vehicle speed reaches a certain speed, for example, 100 km/h, if you turn on the set switch 4 for a short time (within 0.6 seconds) and then turn it off, the vehicle speed at that time will be changed to the new memorized vehicle speed when the set switch 4 is turned on and off.
Set in internal register A as Vn (S3,
S9). Since the vehicle is under control and the ON time is within 0.6 seconds, the process moves to step S14, where it is determined whether the new stored vehicle speed Vn is greater than the original stored vehicle speed Vn-1 plus a predetermined vehicle speed α. It is determined. When Vn>Vn-1+α, a pulse with the maximum duty ratio is output from the output port 1c for about 0.5 seconds as explained in Fig. 3a; otherwise, as explained in Fig. 3b. The control then shifts to normal control (S5). It is preferable to set the above α to, for example, about 10 km/h.

[When stopping constant speed control]

When the cancel switch 8 is turned on, the control flag is set to "0" (S7, S8), and the second
Although not shown in the figure, a signal for activating the release valve 6b is output from the output port 1d, making the negative pressure inside the actuator equal to atmospheric pressure and putting the actuator 6 in an inactive state.

Effects of the Invention As explained above, according to the present invention, when the new memorized vehicle speed after override is higher than the original memorized vehicle speed by more than a predetermined vehicle speed width, the negative pressure inside the actuator that has risen to near atmospheric pressure is rapidly reduced. In order to achieve this, the actuator is driven with a pulse having the maximum duty ratio for a predetermined period of time, and then normal constant speed running is started, which has the effect of reducing the undershoot width. Furthermore, when the new stored vehicle speed does not exceed the predetermined vehicle speed range, the negative pressure within the actuator has not yet been sufficiently released, so the maximum duty ratio does not occur, and overshoot can be prevented.

[Brief explanation of drawings]

Fig. 1 is a block diagram of main parts showing an example of the hardware configuration of an embodiment of the present invention, Fig. 2 is a flowchart for explaining its operation, Fig. 3 is an explanatory diagram of the operation of the present invention, and Fig. 4 is a conventional example. FIG. 1 is a microcomputer, 2 is a vehicle speed sensor,
3 is a frequency voltage converter, 4 is a set switch, 6
is a negative pressure actuator.

Claims (1)

[Claims] 1. In an automobile constant-speed traveling system in which a negative pressure actuator that drives an accelerator link using engine negative pressure as a power source is controlled by a pulse signal having a duty ratio according to the difference between the detected traveling vehicle speed and the stored vehicle speed, when overriding If the memorized vehicle speed is reset while exceeding a certain vehicle speed range with respect to the memorized vehicle speed, the duty ratio is set to the maximum value for a predetermined time at the start of control, and then normal duty ratio control is started and the memorized vehicle speed is A constant speed traveling device for an automobile, characterized in that when the stored vehicle speed is reset in a state where the vehicle speed is below the certain vehicle speed range, normal duty ratio control is performed without increasing the duty ratio to the maximum value. .