JPS6240534B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel control device for an internal combustion engine, and more particularly to a correction function for increasing, decreasing, and shutting off fuel.

Some automobile engines are equipped with a device that shuts off fuel during deceleration in order to improve exhaust purification performance and fuel efficiency during deceleration.

In conventional devices, a throttle opening switch or an accelerator pedal switch is used as a device for detecting a deceleration state, and detecting that the throttle valve is at an idling opening is used as a reference for determining a deceleration state. However, in the conventional method, the above-mentioned deceleration detection switches are required, which makes them expensive, and the opening/closing point of these switches is set when the accelerator pedal is pressed slightly (for example, the throttle valve opening is 1° to 2°). Since the switch must be set to open or close when the switch is depressed, adjustments must be made after it has been installed in the vehicle, which increases man-hours.Furthermore, these switches suffer from wear and tear on the moving parts. During use, the opening/closing point may shift, which may cause malfunction, and to avoid this, regular inspections and adjustments must be made, so maintenance is time-consuming.

In addition, since the deceleration state is determined by a switch that operates on and off, it is difficult to make corrections that accurately match the engine operating state. There is a problem in that it is not possible to make corrections such as reducing the amount of fuel or increasing the amount of fuel at high loads.

The present invention has been made in order to eliminate the drawbacks of the prior art as described above, and is a fuel control device that is capable of making corrections that are suitable for the operating conditions of the engine without using special additional parts such as an accelerator pedal switch. The purpose is to provide

In order to achieve the above object, in the present invention,
The system is configured to perform corrections such as increasing, decreasing, or cutting off the amount of fuel by using two inputs, that is, a basic fuel supply amount signal or a load signal and a rotation signal, and a correction signal that has a predetermined functional relationship. Note that the basic fuel supply amount signal, load signal, and rotation signal described above are signals used in a normal fuel control device (for example, an electronically controlled fuel injection device), so the present invention does not require the addition of special sensors or the like. It can be done by arithmetic processing.

The present invention will be explained in detail below based on the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. In FIG. 1, 1 is a rotation sensor which outputs a rotation signal _S1 corresponding to the engine rotation speed.
As the rotation sensor 1, for example, a crank angle sensor that outputs a pulse for each unit of crank angle is used, and a signal proportional or inversely proportional to the rotation speed is obtained from the frequency or period of the pulse signal.

Next, 2 is a load sensor, which outputs a load signal S ₂ that continuously corresponds to the engine load condition. As this load sensor 2, for example, an air flow meter that detects the amount of intake air can be used, but it can also be used to detect intake negative pressure, throttle valve opening, engine torque, etc. (not necessarily proportional, but inversely proportional). or other functional relationships) may be used.

Next, the calculation circuit 3 generates a basic fuel supply amount signal (hereinafter referred to as basic signal) from the rotation signal S ₁ and the load signal S ₂ .
Output S ₃ . This basic signal S ₃ is, for example, S ₃ =K
Q/N. However, N is the rotation speed, Q is the intake air amount, and K is a constant.

Next, the correction circuit 4 adds corrections corresponding to various engine operating parameters given from the water temperature sensor 5 and the like to the basic signal _S3 to calculate the fuel supply amount signal _S4 .

The actuator 6 (fuel injection valve, etc.) is controlled by this fuel supply amount signal _S4 to supply the necessary fuel.

The configurations 1 to 6 above are similar to conventional fuel control devices, such as electronically controlled fuel injection devices.

Next, the fuel correction function of the present invention will be explained.

Reference numeral 7 denotes a two-input correction signal calculating means, which outputs a correction signal _S5 having a predetermined functional relationship (details will be described later) with respect to the two inputs of the rotation signal _S1 and the load signal _S2 .

The correction circuit 4 performs correction to increase, decrease, or cut off the fuel supply amount in accordance with the above correction signal _S5 .

In addition to the correction circuit 4 that performs correction based on the water temperature signal, etc., a correction circuit dedicated to the correction signal _S5 may be provided separately (for example, the correction circuit 4 and the actuator 6
).

Next, the correction signal calculation means 7 will be explained in detail.

FIG. 2 is a diagram showing the relationship between engine speed N and intake air amount Q.

A solid line _L1 in FIG. 2 is a line showing the relationship between N and Q when driving on a flat road. In the solid line _L1 , when the rotation is low, Q and N are in a nearly proportional relationship, but when the rotation is high, that is, when the vehicle is running at high speed, the loss becomes large, so the increase in Q becomes large.
The area above this solid line _L1 is a high load area where the engine load is relatively heavy. In other words, the vehicle is accelerating or going up an uphill slope. Conversely, the region below this solid line is a light load region where the engine load is relatively light. In other words, the vehicle is decelerating or going downhill. A broken line _L2 set below this solid line indicates a state where the engine shaft output torque is zero. This dashed line
Below L ₂ , the shaft output torque is negative, that is, the engine is driven from the axle side in a decelerating state. Therefore, in the case of an operating state below the dashed-dotted line _L3 , which is set slightly below the broken line _L2, there is no need to supply fuel to the engine, so a fuel cutoff is performed. That is,
The area below the dashed-dotted line _L3 is the fuel cutoff area.

Furthermore, in the high load region above the solid line _L1 , drivability can be improved by increasing the amount of fuel.

Furthermore, by reducing the amount of fuel in the deceleration region between the broken line _L2 and the dashed-dotted line, it is possible to reduce the shock caused by torque fluctuations at the time of fuel cutoff, and to improve fuel efficiency. For example, during sudden deceleration from a high load condition, if the fuel is cut off immediately, a large shock will occur and the passengers will feel uncomfortable. A method of shutting off the engine has been considered, but if a reduced amount of fuel is supplied during the above period, the torque will decrease smoothly, reducing the shock and improving fuel efficiency by the amount of reduced fuel. I can do it.

Therefore, the correction signal calculation means 7 calculates N(signal
If the intersection of S ₁ ) and Q (signal S ₂ ) is in the high load region of solid line L ₁ or higher in Figure 2, the correction coefficient C will be 1<C.
(increase correction), C=1 when in the light load region between the solid line L ₁ and the broken line L ₂ (quantity, that is, no correction),
A correction signal of 0<C<1 (reduction correction) when the deceleration region is between the dashed line _L2 and the dashed-dotted line _L3 , and C=0 (cutoff) when the fuel cut-off region is below the dashed-dotted line _L3 . By outputting _S5 and having the correction circuit 4 perform multiplicative correction, it is possible to perform the above-mentioned corrections for increase, decrease, and cutoff.

That is, depending on the value of the correction coefficient C determined according to N and Q, the fuel supply amount can be controlled to be increased, fixed, decreased, or cut off.

Furthermore, by continuously changing the above-mentioned correction coefficient, the torque fluctuation during correction (particularly when shutting off) becomes small, so there is no possibility of causing discomfort to the occupant.

Note that not only multiplicative correction but also addition/subtraction/division correction can be performed in the same manner.

In addition, if the intersection of N and Q enters the region of dashed-dotted line L ₃ or higher, the fuel cutoff will be canceled and fuel supply will be restarted, but if the cutoff and release are repeated near the limit, torque fluctuations will occur. To avoid discomfort, the release line should be higher than L ₃ . This can be realized by providing the correction signal calculation means 7 with a hysteresis characteristic, or another function generation means may be used to set another level for determining cancellation.

An example of the specific characteristics of the correction signal calculation means 7 is shown in the third example.
As shown in the figure.

In Figure 3, C is a correction coefficient, N and Q
is set to have a predetermined functional relationship with the two inputs.

Alternatively, a region where fuel is cut off (C=0), a region where fuel is reduced (0<C<1), a region where no correction is made (C=1), and a region where fuel is increased (1<C).

The two-input (two-variable) correction signal calculation circuit shown in Fig. 3 can be constructed using an analog circuit, for example, using the same method as the circuit shown in Fig. 6 of Japanese Patent Publication No. 47-40225, but it can also be constructed using a digital circuit. -Easy to implement using a computer. It is a method called table lookup method.
This is a method in which data corresponding to a correction coefficient is stored for each point corresponding to each combination of two input signals, and the data is read out in accordance with each input combination and used as a correction coefficient. In this case, in order to save the number of data, set data at appropriate intervals (not necessarily equal intervals) for each input, and if each input comes between, the combination of that input A method is often used in which a correction coefficient is calculated by interpolating data around the data (four data in the case of two inputs) using interpolation calculation. In this case, other calculation means may also be realized by a digital computer program.

Changes in the judgment level used in the conventional fuel cut judgment method based on other conditions, such as changes according to engine cooling water temperature, changes according to vehicle speed and exhaust temperature, and when changing gears, starting, and extremely low rotation speeds. , prohibition of fuel cut at low vehicle speeds, etc. can be easily combined by changing the characteristics of the function generation means, comparison means, etc. according to each status signal, and by prohibiting correction signals. be able to.

The table look-up method described above can be applied not only to two inputs, but also to one input, three or more inputs, and can be easily changed according to other conditions, so it uses a digital computer. suitable for the system.

Next, FIG. 4 shows another embodiment of the present invention.

In the circuit of FIG. 4, the load signal S ₂ of FIG.
The basic signal S ₃ is used instead of , and the rotation signal S ₁ and the basic signal S ₃ are used as two inputs to the correction signal calculation means 7.

As mentioned above, the basic signal S ₃ has a value proportional to Q/N, so as can be seen from Figure 2, if S ₃ is used, L ₁ to _{L 3} will each become approximately constant values, so correction is required. The signal calculation means 7 becomes simple. Furthermore, since the engine suction negative pressure is also approximately proportional to Q/N, substantially the same effect can be obtained even if a signal corresponding to the suction negative pressure is used.

Further, since there is a relationship between the vehicle speed and the engine load that is almost the same as that for the rotational speed, a signal corresponding to the vehicle speed may be used as the rotational signal.

Note that the basic signal _S3 is not necessarily determined based on the engine speed and engine load as described above. In systems that inject fuel once per revolution, a value proportional to Q/N is used, but 1
When injecting fuel once every fixed time t, Q/
t, that is, the amount of intake air Q serving as a load signal, and therefore a value proportional only to the load signal serves as a basic signal.
This also applies to continuous injection systems.

Additionally, an exhaust sensor (e.g. oxygen sensor) installed in the exhaust system detects the component concentration of the exhaust gas,
In the case of a system that performs feedback control in which the basic signal is corrected by feeding back the signal, the signal after this correction becomes the accurate basic signal, so it can be used to make even more accurate signals. Can make decisions. In addition, in a system that performs this feedback control, it is necessary to stop the feedback control when making corrections such as increasing, decreasing, or shutting off fuel, but in that case, the correction signal of the present invention has a correction coefficient of 1.0 (multiplicative If the feedback control is performed only when the correction amount is 0 (in the case of correction) or 0 (in the case of additive correction) (of course, a slight tolerance may be provided), and the feedback control is stopped when the correction coefficient is other than 1.0. , there is no need for any other special determination means. In this case, in order to prevent feedback control from being stopped due to short-term sudden changes in operating conditions such as gear changes, the correction coefficient should be set to 1.0.
(or a value with a slight margin) After a predetermined period of time, the feedback control is stopped, or the correction signal itself is averaged to make the response slower. You may. The same applies when restarting feed back control. Note that correction to the reference signal mentioned above (correction using correction signal _S5 ) may be smoother and more convenient if the response is not too rapid, so it may be applied with a delay in time or applied in an averaged manner. Good too. These specific methods will be omitted because they can be easily constructed using known circuits.

Note that the arithmetic circuit 3, correction circuit 4, and correction signal calculation means 7 can also be constructed using a microcomputer.

As explained above, the present invention has the following effects.

(1) Throttle switch, accelerator pedal,
Since there is no need for deceleration detection means such as switches, it is possible to avoid increases in price, troublesome adjustments and maintenance, and decreases in reliability caused by using these devices.

(2) More accurate decisions can be made because it is possible to increase, decrease, or cut off the power depending on the engine load condition, that is, the engine torque.

(3) It can be applied to any engine load detection means such as intake air amount, intake negative pressure, throttle opening, engine torque, etc., providing a high degree of system flexibility.

(4) Continuously reduce fuel and cut off fuel,
Since the fuel can be increased continuously and the fuel cutoff can be canceled, there are fewer shocks when the fuel is cut off or canceled.

(5) In addition to fuel cutoff and fuel reduction, it is also possible to increase fuel according to the engine load, so it is possible to supply optimal fuel throughout the engine's operating range.

(6) It is also possible to easily determine whether to stop the feed back control of the feed back control device using the exhaust sensor.

(7) Applicable to both control devices using digital computers and analog control devices.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing one embodiment of the present invention, Fig. 2 is a relation diagram between intake air amount Q and rotational speed N, Fig. 3 is a characteristic diagram of the correction signal calculation means, and Fig. 4 is a diagram of another embodiment of the present invention. It is an example figure. Explanation of symbols 1... Rotation sensor, 2... Load sensor, 3... Arithmetic circuit, 4... Correction circuit, 5... Water temperature sensor, 6... Actuator, 7... Correction signal calculation means.

Claims (1)

[Claims] 1. A basic fuel supply amount signal is calculated based only on a load signal that continuously corresponds to the engine load state, or on the basis of the load signal and a rotation signal that corresponds to the engine rotation signal. In a fuel control device that determines the fuel supply amount by correcting the fuel supply amount signal in accordance with engine temperature, etc., the fuel supply amount signal is indicated by two inputs of the basic fuel supply amount signal or the load signal and the rotation signal. It is determined whether the operating state at that time is in a preset high load area, light load area, deceleration area, or fuel cutoff area in response to the above two inputs continuously, and a correction signal calculating means for outputting a correction signal for increasing the amount of fuel in the case of a light load region, making no correction in the case of a light load region, decreasing the amount of fuel in the case of a deceleration region, and cutting off the fuel in the case of a fuel cutoff region; Correction that increases, quantifies, reduces, or cuts off the fuel supply amount by adding, subtracting, multiplying, or dividing the above correction signal to the fuel supply amount obtained by correcting the basic fuel supply amount signal in accordance with engine temperature, etc. A fuel control device comprising a correction means for performing. 2. When the current operating state indicated by the two inputs is in the high load region or deceleration region, the correction signal calculation means calculates the position of the current operating state and the boundary line between each region. 2. The fuel control device according to claim 1, wherein the value of the correction signal is continuously changed depending on the difference between the two. 3. The fuel control device according to claim 1, wherein the correction means corrects the fuel supply amount according to a signal obtained by averaging or delaying the correction signal. 4. The fuel control device according to claim 1, wherein the rotation signal is a signal proportional or inversely proportional to the engine rotation speed or a signal corresponding to the vehicle speed. 5. Claim 1, characterized in that, as the load signal, any one of an intake air amount, an intake negative pressure, an intake air amount per unit rotation, and an intake air amount per unit time is used. Fuel control device as described in section. 6 Calculate a basic fuel supply amount signal based only on a load signal that continuously corresponds to the engine load state, or based on the load signal and a rotation signal that corresponds to the engine rotation signal, and add the basic fuel supply amount signal to the engine rotation signal. In a fuel control device that determines a fuel supply amount by making corrections corresponding to temperature, etc. and corrections by feedback control corresponding to exhaust gas component concentration, the basic fuel supply amount signal or the load signal and the rotation signal are used. The current operating state indicated by the two inputs is in any of the high load range, light load range, deceleration range, and fuel cutoff range, which are preset in response to the above two inputs. If the load is in the high load area, the amount of fuel is increased, if the load is in the light load area, no correction is made, if it is in the deceleration area, the fuel is decreased, and if it is in the fuel cutoff area, a correction signal is output that cuts off the fuel. and a correction signal calculation means for calculating the fuel supply amount by adding, subtracting, multiplying and dividing the above correction signal to the fuel supply amount obtained by correcting the basic fuel supply amount signal according to the engine temperature, etc. A correction means for performing correction to increase, quantify, reduce, or cut off, and a means for causing the feedback control to be performed only when the correction signal is a correction coefficient of 1 or a correction amount of 0, and stopping the feedback control in other cases. fuel control device.