JPH054255B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a duty control type constant speed cruise control device, and in particular, a device that corrects a set duty corresponding to a target vehicle speed using an integral speed according to a vehicle speed deviation (difference between a target vehicle speed and a running vehicle speed). This is intended to converge the vehicle speed deviation and to prevent over-correction when the road surface suddenly changes by limiting the range of integral correction. [Prior Art] A duty control type constant speed cruise control device sets a duty value necessary for constant speed traveling at a target vehicle speed as a 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 varies depending on the characteristics and variations of the actuator, throttle drive system, and engine, road slope, the presence or absence of engine loads such as air conditioners, and changes in vehicle loads such as transmission gears. A vehicle speed deviation occurs depending on the difference with the duty amount. Figure 2 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 this is 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 resume 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 3. 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). The skip vehicle speed s obtained by adding .
This is to 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) V _B : Control speed width [Problem to be solved by the invention] By the way, in the conventional system, the speed is constant. Since the reference value of the duty amount required for driving is fixed as a set duty, vehicle speed deviations occur due to variations in the actuator system and vehicle load fluctuations. For example, as shown in Fig. 4, the memorized vehicle speed V _M (e.g. 80 Km/
The set duty SD corresponding to h) is 40%,
Assuming that the required duty amount D is 55%, the control center initially located at point A converges to point B as the vehicle speed decreases due to insufficient duty. Since the required duty amount at point B is approximately 55% (in detail, as shown by the dashed line, the required duty amount is 0.1%/
It has a vehicle speed coefficient of about Km/h, but it can be almost ignored in this example), and the control speed width V _B is set to 20 Km/h, for example.
h, a deviation of 20×40-55/100=-3 Km/h will occur, and the control will be at 77 Km/h at point B. Such vehicle speed deviation can be reduced to 0 by correcting the control center from point A to point C in Figure 4, but if the correction speed is slow, it will take time for the deviation to converge, and conversely, if the correction speed is fast, the correction will be difficult. Stability may be compromised by overshooting. Therefore, the present invention effectively overcomes the drawbacks of the conventional system by reducing the vehicle speed deviation while changing the correction speed depending on the size of the difference between the output duty and the set duty (which can also be said to be the size of the vehicle speed deviation in principle). This is what we are trying to resolve. [Means for solving the problem] The present invention turns on and off a control valve of an actuator that adjusts the throttle opening using an output duty D obtained from a control line with a predetermined slope that indicates the conversion characteristics between vehicle speed and duty. In a duty control type constant speed cruise control device that brings the actual traveling vehicle speed closer to a stored target vehicle speed, the difference ΔD between the set duty SD and the output duty D corresponding to the target vehicle speed is determined, and the magnitude of the ΔD is determined. The control line is moved in parallel within a predetermined range at an integral speed corresponding to the set duty cycle.
The present invention is characterized in that it includes a controller that integrally corrects SD in a direction closer to output duty D. [Operation] If the set duty SD is not set to a fixed value, but it is corrected, the vehicle speed deviation can theoretically be reduced to 0, and the vehicle can be driven at a constant speed at the target vehicle speed. At this time,
By changing the correction speed depending on the magnitude of the difference ΔD between the output duty D and the set duty SD, the vehicle speed deviation can be converged as quickly as possible without impairing stability. However, in order to always keep the vehicle speed deviation to a minimum, it is necessary to correct the set duty without limit. However, for example, after gradually increasing the set duty on a steep hill,
If you suddenly go downhill (such as when you cross a mountain pass)
On the other hand, the set duty decreases, but at this time a large vehicle speed overshoot occurs due to the delay in the ECU and the delay in the actuator system. On the other hand, when going from downhill to uphill, the relationship is reversed, but a large vehicle speed undershoot occurs due to the same principle. Therefore, in order to prevent this, the range of integral correction is limited. [Example] Fig. 1 is a flowchart showing an embodiment of the present invention, in which "vehicle speed calculation" is the process of calculating the running vehicle speed Vn shown in Fig. 3, and the following "skip vehicle speed calculation" is the process of calculating the skip vehicle speed of equation (1). This is the process of finding Vs. In this example, Vs is used instead of Vn, so the difference between V _M and Vs becomes the vehicle speed deviation ΔV. "Output duty calculation" uses the control speed width V _B to calculate the duty deviation ΔD=ΔV/
Convert to V _B and add set duty SD
This is a process for finding the output duty D of equation (2). Calculate ΔD from the D and SD obtained at this time, and correct SD according to the size of ΔD (initial value is
SD ₀ ). The correction formula is SD=SD+γ, and γ is calculated from the table below.

〔Effect of the invention〕

As described above, according to the present invention, in a duty control type constant speed cruise control device, since the basic duty value is integrally corrected by changing the speed according to the difference from the output duty, there is no possibility of loss of stability. Therefore, the vehicle speed deviation can be converged at a speed sufficient for practical use. Furthermore, since the range of integral correction is limited, there is an advantage that overshoot and undershoot of the vehicle speed can be reduced when the road surface suddenly changes.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing an embodiment of the present invention, Fig. 2 is a system configuration diagram of a duty-controlled constant speed cruise control device, Fig. 3 is a block diagram of its microcomputer processing, and Fig. 4 shows vehicle speed and duty. It is a control diagram showing the relationship between the following. In the diagram, ECU is the constant speed driving controller, ACT is the actuator, and SL is the 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. In a constant speed cruise control device of duty control type, the difference ΔD between the set duty SD and the output duty D corresponding to the target vehicle speed is determined, and the control line is moved at a predetermined integral speed according to the magnitude of the ΔD. 1. A duty control type constant speed travel control device, comprising a controller that integrally corrects the set date SD in a direction approaching an output duty D by moving the set date SD in parallel within a range.