JPH0330701B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to an electronic engine control device for an internal combustion engine, and more particularly to a fuel cut device for an electronic engine control device for a continuously variable transmission. [Prior art] As a conventional fuel cut device, there is a
Some of these are disclosed in JP-A No. 74625, Japanese Patent Application Laid-open No. 86929/1983, and the like. These systems cut fuel based on the relationship between the throttle valve condition and engine speed. Specifically, when the idle switch is on (throttle valve closed) and the engine speed is above a certain speed (N _FC1 ),
and the engine speed is another constant speed (N _FC2 )
In the above case, when the idle switch is turned on from off, the fuel cut is activated. As a result, the engine speed becomes low, and when the engine speed becomes lower than the release speed (N _REC ), the fuel cut is released. However, N _FC1 > N _FC2 > N _REC
It is. In another conventional example, a low vehicle speed (for example, 8
Km/h), the above fuel cut function does not operate. FIG. 1 is a characteristic diagram for explaining the operation of a conventional fuel cut device. The figure shows vehicle speed VSP [figure (a)], engine speed N _E [figure (b)], idle switch status [figure (c)], and gear ratio when driving in a certain driving pattern. The relationship between i [Figure (d)] and the presence or absence of fuel cut [Figure (e)] is shown. Note that the gear ratio i is a condition unrelated to fuel cut in the conventional example, but is shown for reference. Also, the fuel cut rotation speed N _FC1 is 1600 rpm, N _FC2 is
1250rpm, fuel cut release rotation speed N _REC is 900rpm
This is shown in the example below. In Figure 1, when the idle switch first changes from off to on (point A in the figure), read the engine speed N _E. At this time, the engine speed N _E is 1400 rpm, which is higher than N _FC2 , so
From this moment on, the fuel is cut off. This state continues until the engine speed N _E becomes equal to or less than N _REC (900 rpm) (point B). This is the part designated by reference number 1 in FIG. 4(e). The part with reference number 2 is also the same as the above description. In addition, the part with reference number 1 shows the state of deceleration from constant speed running, and the part with reference number 2 shows the state of deceleration from the time of acceleration. [Problems to be Solved by the Invention] However, in such a conventional fuel cut method, the fuel cut region is determined by the engine speed and a throttle valve switch (idle switch). Therefore, it is suitable for vehicles with stepped (3 to 5 steps) transmissions where there is a proportional relationship between engine speed and vehicle speed during deceleration, but there is no proportional relationship between engine speed and vehicle speed during deceleration. The following problems occur in vehicles equipped with continuously variable transmissions. In other words, in a vehicle with a continuously variable transmission, when the throttle valve closes during deceleration,
When the gear ratio is switched to a low gear ratio (equivalent to a high speed gear such as Top of a stepped transmission, for example, the gear ratio is around 0.5 to 0.7), the engine speed suddenly decreases and the engine speed is slightly higher than the idle speed. number (e.g.
The engine is controlled so that the engine speed decreases to 700 to 900 rpm until it comes to a stop. Therefore, if fuel cut and its release are controlled based on the engine speed, the engine speed will immediately drop below the release speed, resulting in a very short fuel cut range (time). There was a problem of wasting energy. The present invention was made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a fuel cut device for an electronic engine control device for an automobile, which is suitable for a vehicle with a continuously variable transmission. . [Means for Solving the Problems] In order to achieve the above object, the present invention is configured as described in the claims. That is, in the present invention, a fuel cut judgment condition is used based on the on/off state of the idle switch, the vehicle speed, and the gear ratio, and the fuel cut judgment condition is (a) when the idle switch is turned on from off. If the vehicle speed is at least a first predetermined value, fuel cut is started, and the first predetermined value is a high vehicle speed if the gear ratio at that time is a predetermined reference value or more, and a low vehicle speed if it is less than the reference value. (b) If the vehicle speed falls below a second predetermined value during fuel cut, the fuel cut is canceled, and the second predetermined value is set to a single vehicle speed. It is structured as follows. [Operation] As described above, in the present invention, the conditions for fuel cut are determined according to the "vehicle speed", and the vehicle speed is set to a high value when the gear ratio is high. Further, the fuel cut release condition is also determined according to the "vehicle speed", and the vehicle speed is set to a constant value. As described above, in a vehicle equipped with a continuously variable transmission, during deceleration, the gear ratio is set to a low value, and the engine speed rapidly decreases to a low value. Therefore, if the fuel cut determination condition is determined according to the engine speed as in the conventional method, the area in which fuel is cut becomes extremely short. However, by making the judgment based on the vehicle speed as in the present invention and setting the vehicle speed as the fuel cut release condition to a constant value, the fuel cut region can be made as wide as in a vehicle with a stepped transmission, and it is possible to There is no need to worry about the engine stalling due to fuel cut-off even at extremely low vehicle speeds. In addition, by setting the vehicle speed when fuel is cut to a high speed when accelerating with a large gear ratio,
It is possible to prevent jerky vibrations from occurring due to fuel cut and release due to temporary throttle off during acceleration. [Embodiments of the Invention] The present invention will be described below based on the drawings. FIG. 2 is a block diagram showing one embodiment of the present invention. First, the configuration will be explained. 10 is an engine rotation speed sensor (crank angle sensor), and 11 is an air flow meter that measures the amount of intake air. 30 indicates the entire control unit. The detection signals of the engine speed sensor 10 and air flow meter 11 are input to the basic calculation circuit 31 in the control unit 30, and the basic calculation circuit 31 calculates the basic fuel injection pulse width T _P determined by the rotation speed and intake air amount. do. The correction calculation circuit 32 corrects the basic fuel injection pulse width, so the water temperature sensor 15,
It inputs voltage signals from the start switch 16 and other correction inputs 17, and outputs an output pulse _T1 incorporating various corrections. The output signal of the correction calculation circuit 32 is sent to the cut switch 3 that cuts the fuel.
3, the fuel injector 19 is driven by the amplifier 34, and fuel is supplied. A vehicle speed sensor 13 generates a signal having a pulse density proportional to the vehicle speed by turning on and off a reed relay in synchronization with the rotation of a magnet fixed to the rotating shaft of the speedometer cable. 14 is a deceleration sensor, which is composed of an idle switch. 35 is a target gear ratio calculation circuit, and throttle opening sensor 1
2 and the signal from the vehicle speed sensor 13 are input, and the target shift position that provides the minimum fuel consumption rate is calculated. 35-
Reference numeral 1 denotes a comparator which calculates the difference between the target and actual gear ratios using a signal indicating the actual gear ratio from a gear ratio control lever 21, which will be described later, and a signal from a target gear ratio calculation circuit 35. 36 is a motor drive circuit that drives the motor 2 so that the gear ratio calculated by the target gear ratio calculation circuit 35 is achieved.
Outputs a signal for driving 0. Reference numeral 21 denotes a gear ratio control lever, which is composed of a hydraulic control lever that drives the pulley of the belt-driven transmission to achieve a desired gear ratio, and also outputs a signal (phase signal) indicating the actual gear ratio. . This control lever is driven by a motor 20. Note that instead of the position signal from the gear ratio control lever 21, the vehicle speed sensor 13
It is also possible to calculate the gear ratio i directly from the signal of the engine rotation sensor 10 and perform the gear ratio feedback. Here, the gear ratio i is calculated as i=A・N _E /VSP, where A: constant, N _E : engine speed, and VSP: vehicle speed. The fuel cut condition determination circuit 37 includes a deceleration sensor 1
4, a detection signal from the vehicle speed sensor 13, and a signal from the gear ratio control lever 21 indicating the current gear ratio, and when a fuel cut condition described later is satisfied, a control signal is output to the cut switch 33. is off. The fuel cut condition determination circuit 37 also receives the detection signal from the water temperature sensor 15 as input. This is to avoid cutting off fuel because if the water temperature is below 60°C, the engine is warming up and the engine condition is unstable, making it more likely to stall if the fuel is cut off. Although an idle switch is used here as the deceleration sensor 14, there is also a method of inputting the signal from the throttle opening sensor 12 to the fuel cut condition determining circuit 37 and determining deceleration when the opening is below a certain level. Based on such a configuration, fuel cut is performed based on the determination of fuel cut conditions described below. That is, as shown in Table 1 below, (a) the vehicle speed at which fuel cut is started when the idle switch of the engine is turned on from off is set to a high vehicle speed if the gear ratio at that time is equal to or higher than a reference value; If the vehicle speed is less than the standard value, set the vehicle speed to be low (see the classification and fuel cut vehicle speed in Table 1), and (b) release the fuel cut at a preset single vehicle speed ( (See Table 1 for classification and cut release vehicle speed).

【table】

〔Effect of the invention〕

As explained above, according to the present invention, fuel cut conditions are determined based on three parameters: vehicle speed, gear ratio, and deceleration sensor (idle switch). The fuel cut area can be widened to the same extent as in the case of a vehicle with a transmission, and the effect is that it is possible to eliminate the jerky vibration phenomenon of the vehicle due to repeated fuel cut and release when sudden acceleration and sudden deceleration are repeated. can get.

[Brief explanation of drawings]

Fig. 1 is a characteristic diagram for explaining the operation of a conventional fuel cut device, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a diagram showing vehicle speed and throttle opening in the embodiment shown in Fig. 2. A diagram showing the relationship between speed and gear ratio (gear ratio range is between i = 0.45 and i = 2.24),
FIG. 4 is a characteristic diagram for explaining the fuel cut operation in a certain driving mode in the embodiment shown in FIG. <Explanation of symbols> 12...Throttle opening sensor,
13...Vehicle speed sensor, 14...Deceleration sensor (idle switch), 18...Air regulator operation detection section,
20... Motor, 21... Gear ratio control lever, 35...
Target gear ratio calculation circuit, 35-1... Comparator, 36...
Motor drive circuit, 37...fuel cut condition determination circuit, VSP...vehicle speed, i...gear ratio, N _FC1 , N _FC2 ...predetermined engine speed, N _REC ...release speed, N _E ...
Engine RPM.

Claims (1)

[Scope of Claims] 1. A fuel cut device for controlling the engine of a vehicle equipped with a continuously variable transmission that shifts the gear ratio to a lower gear ratio when an idle switch is turned on from off, comprising: an idle switch that is turned on when the throttle valve of the vehicle is in a closed state and turned off when it is in an open state; a vehicle speed detection means that detects the vehicle speed of the vehicle; and a gearshift device that detects the gear ratio of the continuously variable transmission of the vehicle. By inputting signals from the ratio detecting means, the idle switch, the vehicle speed detecting means, and the gear ratio detecting means, the vehicle is controlled according to predetermined fuel cut judgment conditions based on the on/off of the idle switch, the vehicle speed, and the gear ratio. fuel cut condition determination means for outputting a signal for cutting and releasing the cut of fuel supplied to the engine, and the fuel cut determination condition is (a) when the idle switch is turned on from off. If the vehicle speed is at least a first predetermined value, fuel cut is started, and the first predetermined value is a high vehicle speed if the gear ratio at that time is a predetermined reference value or more, and a low vehicle speed if it is less than the reference value. (b) If the vehicle speed falls below a second predetermined value during fuel cut, the fuel cut is canceled, and the second predetermined value is set to a single vehicle speed. A fuel cut device for an electronic engine control device for an automobile, characterized by the following.