JPH0573617B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] During the transition period from turning on the set switch to starting constant speed cruise control, a preliminary initial duty is output to reduce the play of the actuator to reduce the vehicle speed immediately after the start of control. Reduce.

[Industrial application field]

The present invention relates to a duty control type constant speed cruise control device.

[Conventional technology]

A duty control type constant speed cruise control device automatically controls the throttle opening degree by reflecting the difference between the stored vehicle speed and the actual vehicle speed in the duty of the control signal.

Figure 4 shows an example of this type of system, where ECU is an electronic control unit for constant speed driving control, CPU is the central microcomputer, ACT is a negative pressure actuator, and VP is a vacuum pump. The actuator ACT has a control valve CV and a release valve RV, and when the release valve RV is opened, atmospheric air is introduced, and the diaphragm loses its ability to pull the throttle valve.
Therefore, the release valve RV is kept closed while the vehicle is running at a constant speed. The control valve CV then alternately introduces atmospheric pressure and negative pressure to adjust the internal pressure. Duty control by the CPU is performed by changing the ratio of negative pressure introduction time within a predetermined cycle. Therefore, the relationship of duty→actuator internal pressure→throttle opening holds true.

The negative pressure supplied to the actuator ACT is mainly the negative pressure obtained from the intake manifold, with supplementary pressure generated by the vacuum pump VP. An example of the conditions for turning on the vacuum pump VP is that the vacuum switch VSW is turned on and the traveling vehicle speed has decreased by a certain value (for example, 3 km/h) or more from the stored vehicle speed.

[Problem that the invention seeks to solve]

Constant speed driving control is started by storing the vehicle speed when the set SW (switch) is turned from on to off. Therefore, immediately after the start of control, a temporary decrease in vehicle speed (undershoot) occurs due to a delay in the operation of the actuator. Therefore, conventionally, "increase control" is sometimes performed by temporarily outputting an excessive duty immediately after the start of control to compensate for the decrease in vehicle speed. However, even with this method, it is not possible to sufficiently compensate for the time delay.

The present invention attempts to improve this point by preliminarily outputting a duty that reduces the delay (play) in the actuator operation before starting constant speed cruise control.

[Means for solving problems]

The present invention provides a duty control type constant speed cruise control device that stores the vehicle speed at that time as a memorized vehicle speed and starts constant speed cruise control when a set switch is turned from on to off. The present invention is characterized by outputting a duty value when a stroke starts to appear in the duty stroke characteristic of an actuator for opening degree control.

[Effect]

FIG. 1 is a diagram explaining the principle of the present invention. Constant speed control, which stores the target vehicle speed and calculates the output duty, is started at the timing when the set switch is turned from ON to OFF. Therefore, until then, in the conventional system, the duty for controlling the actuator is set to 0%. As described above, as a result, the vehicle speed decreases significantly immediately after the start of the control.

Therefore, in the present invention, a predetermined initial duty is outputted before the start of the control, thereby reducing the delay in the operation of the actuator at the start of the control. This initial duty is determined from the characteristics of the actuator ACT, as shown in FIG. The figure shows the relationship between the stroke of the actuator and the generated force. This characteristic has hysteresis, but the duty is set to 0.
Even if you increase the ACT generation power by increasing it from %,
The stroke remains zero until a certain duty (eg 39%). This is the play that causes a delay in actuator operation. Therefore, even if a duty of less than this is output before starting control, there is no need to worry about increasing the throttle opening, and moreover, it is useful for reducing play. The decision to limit this to the ON period of the set switch was a safety decision. The maximum duty (90%) immediately after the start of control is for the above-mentioned "inflation".

[Embodiment] FIG. 3 is a flowchart showing an embodiment of the present invention. Step S1 is to determine the presence or absence of switch inputs (cancel signals) for the clutch, parking, brake, etc. shown in FIG. 4. If any of these signals is present, the cancel mode is set in step S2. The cancel mode is a normal mode in which constant speed driving control is canceled. If there is no cancel signal, determine the set switch (step S3),
If it is on, check the current mode (step S4), and if it is cancel mode, go to step
Move to set mode with S5. This set mode is the constant speed running control mode. If it is not the cancel mode, in other words, if it is the set mode, the process moves to the coast mode in step S6. This mode uses the same set SW for deceleration control. On the other hand, if the set SW is off in step S3, the mode is determined in step S7, and if it is coast mode, the mode shifts to set mode in step S8. This is set when decelerating in coast mode.
This means that the vehicle speed when the SW changes from on to off is newly memorized and constant speed control is resumed. The above is the distribution of modes.

Next, the mode is determined in step S9, and if it is not set mode (cancel mode or coast mode), the duty is set to 0% in step S11. On the other hand, if the mode is set, the state of the set SW is checked in step S10. If it is on, an initial duty is set in step S12, and if it is off, an output duty is calculated in step S13. Since the actual duty output is performed in the subsequent processing, the maximum duty is output instead of the calculated output duty during the incubation time after the set switch is turned off.

〔Effect of the invention〕

As described above, according to the present invention, since the amount of play in the actuator can be set to zero at the start of constant speed cruise control, it is possible to reduce a decrease in vehicle speed due to a delay in the operation of the actuator immediately after the start of constant speed cruise control. There are advantages.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a characteristic diagram of an actuator, Fig. 3 is a flowchart showing an embodiment of the invention, and Fig. 4 is a configuration diagram of a duty control type constant speed cruise control device. be.

Claims (1)

[Claims] 1 In a duty control type constant speed cruise control device that stores the vehicle speed at that time as a memory vehicle speed and starts constant speed cruise control when the set switch is turned from on to off, throttle opening control is performed during the on period of the set switch. A duty control type constant speed traveling control device, characterized in that a duty value is output when a stroke starts to appear in the duty stroke characteristics of an actuator for use in a vehicle.