JPH043333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a constant speed traveling device for automobiles, commonly called autodrive or speed control.

A constant-speed vehicle is a device that automatically controls the vehicle speed and maintains it at a constant speed without having to press the accelerator pedal when the desired vehicle speed is set during driving. Alternatively, the control valve coil of the negative pressure actuator that drives the accelerator link using vacuum pump negative pressure, etc. as a power source is set to A device is known that is driven by a pulse signal with a corresponding duty ratio.

[Conventional technology]

Conventionally, the calculation of the duty ratio DU (%) according to the difference between the detected vehicle speed and the target vehicle speed described above is calculated using the following formula, where the detected vehicle speed is XN, the target vehicle speed is XA, the set duty ratio is SD, and the control speed width is VB. was required by.

DU=[(XA-XN)/VB]+SD...(1) However, 0≦DU≦100 Here, the set duty ratio SD is set at the design stage as a duty ratio that allows constant speed driving at a certain vehicle speed, for example, 80 km/h. etc., and the control speed width VB is the width of the vehicle speed difference in which the output duty ratio changes.

FIG. 6 is a diagram showing an example of the vehicle speed difference vs. output duty ratio characteristic defined by the above equation (1), and the control speed width VB and set duty ratio SD are expressed as shown.

[Problem that the invention seeks to solve]

Incidentally, the set duty ratio SD is determined at the design stage as described above, but due to the characteristics of the actuator, variations in the driving force of the vehicle, etc., it is not possible for each vehicle to always obtain the desired actual vehicle speed with the set duty ratio SD. There is no guarantee that it will be possible. The same applies when the running resistance varies due to changes in the road surface. In such a case, the vehicle is driven at a speed where the vehicle speed difference and the output duty ratio DU are balanced. That is, for example, if the set duty ratio SD is too small, the vehicle will run at a constant speed with a deviation of ΔXN as shown at point P in FIG.

As a method to reduce such steady-state deviation, the control speed width is changed to VB as shown by the dotted line in Figure 6.
It is conceivable to make the so-called control gain larger by reducing it to VB'. In this way, the steady-state deviation becomes small to ΔXN', as shown in the figure. However, in this case, since the control gain becomes large, there is a drawback that stability is likely to be impaired by disturbances and the like.

The present invention has been made in view of the above circumstances, and its purpose is to reduce the steady-state deviation caused by an inappropriate set duty ratio while ensuring control stability.

[Means for solving problems]

In order to achieve the above object, the present invention calculates an output control amount according to the difference between a detected running vehicle speed and a preset set vehicle speed based on a control gain for calculating the output control amount and a set control amount. In a constant speed traveling device for an automobile, comprising an output control amount calculation means for calculating an output control amount, and a drive means for driving a throttle valve driving actuator based on the output control amount, the output control amount calculated by the output control amount calculation means is A set control amount correcting means is provided which continuously corrects a preset set control amount based on the constant speed cruise control and uses it as a set control amount for calculating the output control amount of the output control amount calculation means. Further, the set control amount correction means corrects the set control amount in accordance with the average value of the output control amounts.

[Effect]

If the preset control amount is inappropriate, the actual vehicle speed will have a steady deviation from the target vehicle speed, but in this case, there will be a difference between the output control amount and the set control amount depending on the steady deviation. The set control amount correction means corrects the set control amount applied to the output control amount calculation means in a direction that reduces the steady state deviation, and the steady state deviation is controlled to be small.

〔Example〕

FIG. 1 is a configuration diagram showing an embodiment of the present invention, and an output duty ratio calculating means 1 calculates an output duty ratio according to a difference between a detected traveling vehicle speed and a preset vehicle speed. Calculate based on the control vehicle speed range and set duty ratio for calculation. The driving means 3 generates a pulse signal having a duty ratio corresponding to the output duty ratio calculated by the output duty ratio calculating means 1, and generates a pulse signal for use in a control valve in a throttle valve driving actuator 2 using engine negative pressure as a power source. Drive the coil 2a. The average value calculation means 4 calculates the average value of the output duty ratios calculated by the output duty ratio calculation means 1. The set duty ratio correcting means 5 corrects the set duty ratio (fixed value) set in advance according to the average value of the output duty ratios calculated by the average value calculating means 4, and adjusts the output duty ratio of the output duty ratio calculating means 1. Set duty ratio for calculation.

FIG. 2 is a block diagram of essential parts of an embodiment of the present invention.

In the figure, 10 is a reed switch for detecting the speed of an automobile, and 11 is a permanent magnet rotated 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 DC voltage having a level proportional to the vehicle speed in a frequency-voltage conversion circuit (F/V conversion circuit) 12. F/V conversion circuit 1
The output voltage of 2 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 converted into a digital quantity by the A/D converter 16 and then input to the input port of the microcomputer 17. The microcomputer 17 generates a pulse signal having an output duty ratio according to the difference signal, and when the AND circuit 26 is open, the pulse signal passes through the AND circuit 26 and controls the actuator 19 via the amplifier 20. It is added to the valve coil 19i.

The actuator 19 includes a control valve 19a and a release valve 19b, and the control valve 19a is connected to the amplifier 2.
Opening/closing is controlled by a control valve coil 19i that is excited with an output of 0. When the control valve coil 19i is energized, the atmospheric pressure from the port 19c is cut off and the intake pipe negative pressure from the port 19d is introduced into the chamber 19e, and when the energization is cut off, the negative pressure from the port 19b is introduced. is shut off and atmospheric pressure is supplied to chamber 19e from port 19c.
to be introduced. The release valve 19d is controlled to open and close by a release valve coil 19j driven by the output of the self-holding circuit 22 via the amplifier 21. When energized, the release valve 19d shuts off the atmospheric pressure from the port 19f, and when the energization is cut off, this valve shuts off. Atmospheric pressure is introduced into chamber 19e. By controlling the pressure in the chamber 19e as described above, the diaphragm 19g moves, which causes the rod 19 connected to the accelerator link (not shown) to move.
h is moved in its axial direction, and as a result, the opening degree of the throttle valve is controlled.

Further, an AND circuit 25 is provided which receives the output of the set switch 23 and the output of the high-speed limiter circuit 24, and the output of the AND circuit 25 closes the analog switch 13 and presets the self-holding circuit 22. When the self-holding circuit 22 is preset, the AND circuit 26 is opened and the release valve coil 19b is energized through the amplifier 21, so that traveling control becomes possible. The high-speed limiter circuit 24 closes the AND circuit 25 when it receives a chime signal indicating that the vehicle has reached a high speed of, for example, 100 km or more, thereby preventing the set vehicle speed from being memorized. Further, the cancel switch 28 is
This is a switch that resets the self-holding circuit 22, and when reset, the self-holding circuit 22 stops energizing through the amplifier 21. Residence switch 27
is used to restart the constant speed driving control that was interrupted by the cancel switch 28. When this button is pressed, the constant speed driving control is performed using the originally set vehicle speed as the target value. In addition, the constant speed limiter circuit 29
is for forcibly resetting the self-holding circuit 22 when the vehicle speed drops to 30 km or less, for example.

FIG. 3 is a flowchart showing an example of output duty ratio calculation/output processing executed by the microcomputer 17, and FIG. 4 is a flowchart showing an example of output duty ratio averaging processing executed by the microcomputer 17. Explain.

The microcomputer 17 executes steps S2 to S4 for calculating the duty ratio shown in FIG. 3 at predetermined intervals, for example, every 50 msec (S1). This process begins with the output of the A/D converter 16, that is, the detected vehicle speed XN, and the target vehicle speed XA stored in the storage circuit 14.
(vehicle speed difference) (S2), and then calculates the current output duty ratio DU using the following formula (S3).

DU = [(XA - Now, this SD' is variable.

After calculating the current output duty ratio DU in step S3, the microcomputer 17 sends a pulse signal having a duty ratio equal to the calculated duty ratio from the output port to the AND circuit 26 (S4).

In addition, the microcomputer 17 executes the process shown in FIG. 4, for example, every 50 msec.
The set duty ratio SD' used to calculate the output duty ratio is constantly corrected. In other words, each time a correction period arrives, the output duty ratio DU at that time
From the average value DUmean of the previous output duty ratio, the new average value of the output duty ratio is calculated by the following formula:
Calculate DUmean (S10).

DUmean=(M×DUmean+DU)/(M+1)
...(3) Here, M is an averaging coefficient (smoothing coefficient), for example, 7.

After calculating the average value DUmean of the output duty ratios, the microcomputer 17 then calculates a set duty ratio SD' for calculating a new output duty ratio using the following equation (S11).

SD′=SDbace+(DUmean−SDbace)/K
(4) Here, SDbace is a value determined at the design stage, etc., corresponding to the conventional set duty ratio, and is a fixed value stored in advance in the ROM, etc. of the microcomputer 17. Further, K is a constant that substantially determines the variable range of the set duty ratio SD' for calculating the output duty ratio, and is set to about 2, for example.

In this embodiment, as described above, the set duty ratio SD' for calculating the output duty ratio is corrected based on the average value DUmean of the output duty ratio at each predetermined period. If a speed deviation ΔXN occurs under control using the set duty ratio SDbace, then the average value DUmean of the output duty ratio at that time and SDbace
The output duty ratio SD′ is DUmean according to the difference between
The vehicle speed difference versus output duty ratio characteristic curve is changed, for example, from the solid line to the dotted line in the figure, and the steady-state deviation is reduced by ΔXN'.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various other additions and changes are possible. For example, in a system in which a plurality of pre-fixed set duty ratios are provided for each target vehicle speed, each of them may be modified.

〔Effect of the invention〕

As explained above, according to the present invention, even if the preset set control amount is inappropriate, the set control amount correction means continuously adjusts the steady state deviation in the direction of decreasing the steady state deviation during constant speed driving control. Since the set control amount for calculating the output control amount in the output control amount calculation means is corrected, the steady-state deviation can always be made small during constant speed driving control, and there is no need to change the control gain, so stability is improved. It won't be damaged.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of main parts of an embodiment of the present invention, and FIG. 3 is a flowchart showing an example of output duty ratio calculation/output processing executed by the microcomputer 17. , FIG. 4 is a flowchart showing an example of the output duty ratio averaging process executed by the microcomputer 17, FIG. 5 is an explanatory diagram of the effects of the present invention, and FIG. 6 is an explanatory diagram of conventional problems. In the figure, 1 is an output duty ratio calculation means;
2 is an actuator, 2a is a control valve coil, 3 is a driving means, 4 is an average value calculation means,
5 is a set duty ratio correction means, 10 is a reed switch, 11 is a permanent magnet, 12 is a frequency-voltage conversion circuit, 13 is an analog switch, 14 is a memory circuit, 15 is a differential amplifier, 16 is an A/D converter,
17 is a microcomputer, 19 is an actuator, 19a is a control valve, and 19i is a control valve coil.

Claims (1)

[Claims] 1. Output control amount calculation that calculates an output control amount according to the difference between the detected traveling vehicle speed and a preset set vehicle speed based on a control gain for output control amount calculation and a set control amount. and a driving means for driving an actuator for driving a throttle valve based on the output control amount, the constant speed driving device comprising: a drive means for driving an actuator for driving a throttle valve based on the output control amount calculation means; Constant-speed driving for an automobile, characterized in that it is equipped with a set control amount correction means that continuously corrects the set control amount during constant speed driving control to use the set control amount for calculating the output control amount of the output control amount calculation means. Device. 2. The constant speed traveling system for an automobile according to claim 1, wherein the set control amount correcting means corrects the set control amount according to an average value of the output control amount.