JPH0331610B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a duty control type constant speed cruise control device that integrally corrects a set duty corresponding to a target vehicle speed, and is particularly intended to prevent hunting immediately after the target vehicle speed is set. (Prior art) A duty control type constant speed driving control device sets the duty value required for constant speed driving at a target vehicle speed as the set duty, and adds or sets a duty amount according to the difference between the target vehicle speed and the traveling vehicle speed to the set duty. It performs constant speed driving control while subtracting and outputting. However, the required duty amount changes depending on variations in the characteristics of the actuator, throttle drive system, and engine, the slope of the road surface, the presence or absence of engine load such as the core controller, and changes in vehicle load such as transmission gear. A vehicle speed deviation occurs depending on the difference with the duty amount. Figure 4 is a system configuration diagram showing an example of this type of constant speed cruise control device.The controller ECU is turned on/off by a magnet that rotates in proportion to the rotation of the vehicle drive shaft.
The vehicle speed is detected by the signal from the vehicle speed sensor, which is equipped with a reed switch that turns off. When the set switch is turned on, the ECU memorizes the vehicle speed and
After OFF, the control valve of actuator ACT is duty-controlled. control valve
When ON, negative pressure is introduced, increasing the force generated by the diaphragm linked to the throttle SL. When OFF, atmospheric air is introduced and weakens the diaphragm generating force. During this time, the release valve is turned on to cut off the atmosphere. Cancel signal (clutch switch (neutral start switch for A/T vehicles),
parking switch or brake switch)
When input, both the control valve and release valve are turned OFF, atmospheric air is introduced from both, and the control is immediately stopped. If you turn on the restart switch after canceling, driving control at the previously memorized vehicle speed will be restored. A microcomputer is used for the ECU, and the processing there is divided into blocks as shown in Figure 5. The output duty D for controlling the control valve on and off is determined according to the difference between the target vehicle speed (memorized vehicle speed) V _M and the traveling vehicle speed Vn, but in detail it is not the traveling vehicle speed Vn itself but the vehicle speed change component (differential component). Use the cap vehicle speed Vs which is the sum of . This is to advance and compensate for dead time due to actuator delay, throttle, drive system hysteresis, and play. Therefore, the skip vehicle speed Vs is determined by the following formula. Vs=Vn+K(Vn-Vo _-1 )...(1) Vn: Current vehicle speed Vo _-1 : Previous vehicle speed K: Proportionality constant Further, the output duty D is determined by the following equation. D=SD+V _M -V _S /V _B ...(2) SD: Set duty V _M : Target vehicle speed (memory vehicle speed) VB: Control speed width V _M - V _S in the above equation is the vehicle speed deviation ΔV, and the control speed Since the width V _B is the reciprocal of the control gain (the slope of the control line) G, equation (2) can also be expressed as follows. D=G×ΔV+SD (3) By the way, if the reference value of the duty amount required for constant speed running is fixed as a set duty, vehicle speed deviation will occur due to variations in the actuator system and vehicle load fluctuations. For example, as shown in Fig. 6, the set duty SD corresponding to the memorized vehicle speed V _M (for example, 80 km/h) is 40%, and the required duty amount D is
Assuming that it is 55%, the control center initially at point A converges to point B as the vehicle speed decreases due to insufficient duty. The required duty amount at point B is also approximately 55%.
Therefore, (in detail, the required duty amount has a vehicle speed coefficient of about 0.1%/Kmh as shown by the dashed line, but in this example it can be almost ignored), the control speed width V _B is set to, for example, 20Km/h. For example, a deviation of 20 x 40 - 55/100 = -3 km/h will occur, and the speed will be controlled at 77 km/h at point B. Such vehicle speed deviation can be reduced to zero by correcting the control center from point A to point C in FIG. For this purpose, the control line in the figure may be moved in parallel from the solid line position to the broken line position. One of these methods is to change the correction speed depending on the magnitude of the difference ΔD between the output duty D and the set duty SD. The equation below is a modified equation based on the above method, and the correction term β takes the values shown in Table 1. SD=SD+β……(4)

[Means for solving problems]

In the present invention, a control valve of an actuator that adjusts the throttle opening is controlled on and off using an output duty D obtained from a predetermined gradient control line that indicates the conversion characteristics between vehicle speed and duty, and the actual traveling vehicle speed is memorized. When approaching the target vehicle speed, set duty SD corresponding to the target vehicle speed.
and the output duty D, and the controller calculates a correction term β according to the difference ΔD between the output duty D and the output duty D, and uses the correction term β to correct the set duty SD in a direction closer to the output duty D. The control device is characterized in that, for a certain period of time after the target vehicle speed is set, the complement term β of the set duty SD is fixed at a constant value that varies in the vehicle speed range. [Operation] Immediately after the target vehicle speed is set, the previous state is not known, so if the value of the correction term β is selected from Table 1, it may be too large. Therefore, in the present invention, the value of β is limited to a constant value that provides a slow integration speed for a certain period of time (for example, 14 seconds) after setting. In addition, by varying this value depending on the vehicle speed range, optimization is achieved taking into account differences in vehicle gain. [Embodiment] FIG. 1 is a flowchart showing an embodiment of the present invention. The SD correction method in this example uses two integral elements.
It uses DM and SD1, and is expressed as SD=SD1+(DM-SD1)/n...(5). DM is a high-speed integral element and is expressed as DM=DM+α (6), and if the correction term α is set to, for example, α=(D−DM)/K (7), it becomes the average value of the output duty D. On the other hand, SD1 is a slow integral element and is expressed as SD1=SD1+β...(8). The initial value of DM, SD1, and SD is SD ₀ , and the third
It changes following the duty D as shown in the figure.
SD1 is an element that translates the control line in FIG. 6, while DM is an element that rotates the control line around point A toward point C. Since the method explained in Table 1 is a one-element integration method that does not use this DM, if the two-element method SD1 is used, equation (4) has the same meaning as equation (8). The flowchart in Figure 1 changes the control within and after 12 seconds after setting. That is, first, after calculating the vehicle speed, it is determined whether 12 seconds have elapsed since the setting. If 12 seconds have passed, find the difference between the output duty D and the set duty SD and calculate D-SD according to Table 1.
Determine β according to the size of . However, within 12 seconds after setting, β is determined uniquely from the vehicle speed range and the magnitude relationship of D and SD. In other words, in the next step, it is determined whether the vehicle speed is 60km/h or higher, and
In the low speed range below h, β=±0.04%/sec. + means when D>SD, - means when D≦SD. If this is a high range exceeding 60 km/h, β = ±
It becomes 0.2%/sec. In this way, β is determined within 12 seconds after setting, regardless of the magnitude of D-SD. At this time, β is used to set the integral correction speed to a gentle constant value. Once β is determined as described above, SD1 is calculated using equation (8) in the next step, and in the method using DM, DM is calculated using equation (6), and then SD is calculated using equation (5). If DM is not used, SD is calculated using equation (4)), and then the duty D is calculated using equation (1) in the next step.
Calculate and output. One cycle of this flowchart is, for example, 50 msec. FIG. 2a is an explanatory diagram of the operation of the present invention. By keeping the correction speed of SD1 at a gentle constant speed until a certain period of time T has elapsed after setting, it is possible to suppress the amount of change in other factors due to a change in duty. As a result, the occurrence of hunting as shown in FIG. 2B can be prevented. [Effects of the Invention] As described above, the present invention has the advantage of being able to eliminate vehicle speed deviations that occur on uphill roads, etc., and also being able to prevent hunting immediately after the target vehicle speed is set.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of its operation, Fig. 3 is an explanatory diagram of a two-element integral correction method, and Fig. 4 is a system configuration of a constant speed cruise control device. FIG. 5 is a block diagram of the microcomputer processing, and FIG. 6 is a characteristic diagram of duty control. In the diagram, ECU is a controller, ACT is an actuator,
SL is throttle.

Claims (1)

[Claims] 1 The control valve of the actuator that adjusts the throttle opening is controlled on and off using the output duty D obtained from a control line with a predetermined slope that indicates the conversion characteristics between vehicle speed and duty, and the actual traveling vehicle speed is adjusted to the stored target vehicle speed. When approaching the target vehicle speed, a correction term β is calculated according to the difference ΔD between the set duty SD corresponding to the target vehicle speed and the output duty D, and the set duty SD is corrected in the direction of approaching the output duty D using the correction term β. The duty control type constant speed cruise control device is equipped with a controller that controls the target vehicle speed, and is characterized in that the correction term β of the set duty SD is fixed at a constant value that varies depending on the vehicle speed range for a certain period of time after the target vehicle speed is set. A duty control type constant speed travel control device.