JPH0530651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a set deviation reduction method for a duty control type speed control device for an automobile.

[Conventional technology]

An automobile speed control device that controls the negative pressure in the actuator and adjusts the throttle opening through duty control is configured as shown in FIG. 3, for example. In the figure, reference numeral 1 denotes a throttle valve, which is provided in a flow path for supplying fuel to an internal combustion engine of an automobile.
An accelerator pedal 3 is connected to the throttle valve 1 via a link mechanism 2, and the degree of opening of the valve 1 changes depending on the amount of pedal depression. A diaphragm 5 of an actuator 4 is also connected to the link mechanism 2 . Solenoid valves 7 and 8 are connected to the working chamber 6 of the actuator 4, and the solenoid valve 7 communicates the working chamber 6 with a negative pressure source such as an intake manifold when the line 9 becomes high level and is excited. On the contrary, line 9
is at a low level, the working chamber 6 is communicated with the outside atmosphere. On the other hand, the solenoid valve 8
When it is at a high level, it is shut off, and when it is at a low level, the working chamber 6 is communicated with the outside atmosphere. As the absolute value of the negative pressure in the working chamber 6 increases, the opening degree of the throttle valve 1 increases. A control signal is applied to line 9 from AND gate 11 via buffer 12 .
Similarly, a release signal is applied to line 10 from AND gate 13 via buffer 14. One input of AND gates 11 and 13 has
The above signal is given from a 1-chip microcomputer 15.

A vehicle speed pulse from a vehicle speed detection means 16 for detecting the actual vehicle speed is inputted to an interrupt input terminal iRQ of the microcomputer 15 via a buffer 17. In the vehicle speed detection means 16, a plurality of magnetic poles N and S are magnetized at intervals in the circumferential direction of a rotary disk 18 that rotates together with the wheels, and the actual vehicle speed is detected from a reed switch 20 that is electrically connected by the magnetic force of the magnetic poles. A pulse having a frequency proportional to is output.

A set switch 21 and a resume switch 22 for constant speed running are connected to the microcomputer 15. When the set switch 21 is operated while the car is running, the vehicle speed represented by the pulse from the vehicle speed detecting means 16 is stored in the memory 19 of the microcomputer 15, and this is used as the set vehicle speed and is thereafter used as a control for changing the duty by the AND gate 11. A signal is given, and the solenoid valve 7 is duty-controlled. At this time, the level of the release signal given from the microcomputer 15 to the AND gate 13 is at a high level, and the electromagnetic valve 8 is in a state of shutting off the atmosphere.

A clutch switch 23, a parking switch 24, and a brake switch 25 are provided to cancel constant speed running. clutch switch 23
is turned on by depressing the clutch pedal, the parking switch 24 is turned on by pulling the handbrake, and the brake switch 25 is turned on by pulling the handbrake.
becomes conductive when the brake pedal is depressed. The outputs from clutch switch 23 and parking switch 24 are routed to line 28 via OR gates 26 and 27. The output from brake switch 25 is led out to line 28 via OR gate 27. The signal from line 28 is applied to AND gates 11,13.

FIG. 4 is a block diagram showing the processing system inside the conventional microcomputer 15.
is a differentiation circuit that differentiates the traveling vehicle speed Vn and compensates for the advance angle,
41 is the set vehicle speed V _M in the memory 19 and the differential output
42 is an adder, 43 is a set duty (SD) setter, and 44 is a duty converter. The duty converter 44 converts the output of the comparator 41 (to simplify the explanation, it will be referred to as V _M -Vn) into a duty. At this time, the set vehicle speed V _M is set as a set duty SD, and the difference from Vn is added to this. The duty is taken into consideration. D is an output duty, which is used for negative pressure control of the actuator 4.

FIG. 5 is a control diagram in this case, and the output duty D is expressed by the following equation.

D=100(V _M −Vn)/V _B +SD (1) Here, VB is the control speed width.

[Problem that the invention seeks to solve]

The set duty SD is output as a value corresponding to the set vehicle speed V _M in the memory 19, and ideally it is stabilized at D=SD by duty control using equation (1). However, this set duty SD is an average value required for constant speed driving, so even if the actuator is operated with this value, depending on the vehicle, the set vehicle speed V _M may not be maintained, and the road slope, transmission gear, air conditioning system, etc. In general, vehicle speed often decreases due to shock absorbers, etc. (the reverse may also be the case). in this case,
The duty is greater than the set duty SD to try to recover the vehicle speed. However, at some point it settles down to balance itself with the vehicle. In the example shown in Figure 5, the vehicle speed settles at V ₁ , which is lower than V _M ,
This shows a state in which the operating point has moved from P ₀ to P ₁ .
At this time, the difference between the set duty SD and the actual stable duty _D1 becomes the set deviation ΔD, which causes the inconvenience that the control target value for constant speed running substantially decreases from V _M to _V1 (the reverse may also be the case).

The present invention attempts to reduce such set deviation.

[Means for solving problems]

The present invention provides a speed controller for an automobile that converts the difference between a set vehicle speed and a traveling vehicle speed into a change in duty to control negative pressure in an actuator and adjusts a throttle opening using a diaphragm of the actuator. In the set deviation reduction method that reduces the difference between the set duty corresponding to the actual stable running vehicle speed and the output duty corresponding to the actual stable running vehicle speed,
The present invention is characterized in that the control speed width of the vehicle speed-duty conversion characteristic near the set vehicle speed is set to be larger than other parts.

[Effect]

Reduce VB (increase gain) using formula (1)
The set deviation decreases in proportion to this, but on the other hand, the influence of disturbances in the vehicle speed sensor signal, etc. increases. Therefore, the control speed width is not made constant as shown in FIG. 5, but the gain is lowered near the set vehicle speed _VM (for example, ±1 km/h), and the gain is raised in other regions. FIG. 1 is an explanatory diagram of the principle of the present invention, showing the conversion characteristics of vehicle speed Vn and duty D. VB1 and VB2 are control speed widths, and have a relationship of VB1>VB2. VB1
is applied to the range of V _M ±1 Km/h, and VB2 is applied to other ranges.

〔Example〕

FIG. 2 is a flowchart showing one embodiment of the present invention. The formula for calculating duty D is as follows.

D=100/VB1(V _M −Vn)+SD ……(2) D=100/VB2(V _M −1−Vn)+100/VB1+SD ……(3) D=100/VB2(V _M +1−Vn) −100/VB1+SD ……(4) Equation (2) is for |V _M −Vn|≦1Km/h,
In this case, use VB1. On the other hand, (3) and
Equation (4) is when |V _M -Vn| > 1 Km/h, Equation (3) is when the vehicle speed is down (-1 is added to V _M ), and Equation (4) is when the vehicle speed is up (+1 is added to V _M) . ). In all of these cases, use VB2.

In this way, the duty change in response to a change in vehicle speed near the set vehicle speed is small, so the set deviation can be reduced.Moreover, when a greater change in vehicle speed occurs, the duty changes greatly, so the set vehicle speed can be quickly reached. Can return.

〔Effect of the invention〕

As described above, according to the present invention, there is an advantage that the set deviation can be reduced while suppressing control disturbances and hunting caused by disturbances in the vehicle speed signal.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a flowchart showing an embodiment of the invention, Fig. 3 is a block diagram of an automobile speed control device, and Fig. 4 is a conventional duty control system. The block diagram, FIG. 5, shows its control characteristics. In the figure, 1 is the throttle, 4 is the actuator,
15 is a microcomputer, 16 is a vehicle speed detection means, 19 is a memory, and 21 is a set switch.

Claims (1)

[Claims] 1 Corresponding to the set vehicle speed of an automobile speed control device that converts the difference between the set vehicle speed and the traveling vehicle speed into a change in duty, controls the negative pressure in the actuator, and adjusts the throttle opening with the diaphragm of the actuator. In the set deviation reduction method for reducing the difference between the set duty and the output duty corresponding to the actual stable running vehicle speed, the control speed width of the vehicle speed-duty conversion characteristic near the set vehicle speed is set to be larger than other parts. Set deviation reduction method for automotive speed control equipment.