JPH0639073Y2 - Fuel supply device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Use) The present invention relates to a fuel supply device for an internal combustion engine.

(Prior Art) As a fuel supply device for an internal combustion engine, a fuel injection type is known, but in such a fuel injection type, based on the intake air amount Q and the rotational speed N of the engine, etc. The following formula (1),
By (2), the fuel injection amount (injection pulse width) T ₁ is calculated, an injection pulse signal is output to the fuel injection valve, and the fuel injection amount from the fuel injection valve is controlled.

T _P = K ・ Q / N… 1 T _i ＝ T _P・ COEF ・ α + T _S … 2, where T _P is the basic fuel injection amount, K is a constant, COEF is the sum of the respective correction factors due to cooling water temperature, etc. α is a feedback correction coefficient by the air-fuel ratio sensor, and T _S is an ineffective pulse width due to the voltage correction (see JP-A-58-28568, etc.).

(Problems to be solved by the invention) However, even if the fuel injection amount is controlled in this way, for example, if there are variations in the flow rate characteristics of the fuel injection valve,
The desired injection amount control cannot be obtained.

That is, if there is variation in the flow rate characteristic, an error will occur in the fuel injection amount when the feedback control by the air-fuel ratio sensor is not performed, and in the feedback control region, the variation correction of the flow rate characteristic will be delayed. I will end up. Therefore, there is a problem that the output performance and exhaust performance of the engine are deteriorated.

In addition, there is a control method for learning the fuel injection amount, but if there are variations in the flow rate characteristics, it takes a long time from the start of learning to the completion of learning, and the above problems may occur during this period. Is inevitable.

Note that FIG. 8 shows the variation in the flow rate characteristics of the fuel injection valve, but the injection valve with the flow rate adjustment mechanism requires time and effort for adjustment,
The cost will increase.

The present invention aims to solve such a problem.

(Means for Solving the Problem) As shown in FIG. 1, the present invention calculates a fuel injection amount based on an operating state of an engine, and outputs an injection pulse signal to a fuel injection valve 1 based on the fuel injection amount. In a fuel supply system for an internal combustion engine, which is equipped with a control means 2 for outputting the fuel injection valve 1, the fuel injection valve 1 selected from any one of the groups of fuel injection valves divided into a plurality of groups according to the magnitude of the flow rate characteristic is attached to the engine. At the same time, a resistor 3 having a resistance value corresponding to the flow rate characteristic group is provided, the flow rate characteristic is identified based on the resistance value of the resistor 3, and the pulse of the injection pulse signal is corrected by a correction value according to the flow rate characteristic. Four correction means for correcting the width are provided, and the correction means 4 is set so that when the resistance value is infinite, the fuel injection valve 1 is regarded as a group of intermediate flow rate characteristics.

(Operation) Therefore, the flow rate characteristic of the fuel injection valve 1 is managed in group units by the resistance value of the resistor 3 according to the flow rate characteristic of the fuel injection valve, and the pulse width of the injection pulse signal is corrected according to the flow rate characteristic. Therefore, the required injection amount can be obtained for all cylinders against variations in flow rate characteristics.

Further, when the resistance value is infinite, the fuel injection valve 1 is regarded as a group of intermediate flow rate characteristics, and therefore, in an engine equipped with the fuel injection valve 1 having a larger or smaller flow rate characteristic, the resistor 3 should be installed. Even if the mounting is forgotten or the resistor 3 is dropped due to vibration or the like, for example, for a fuel injection valve of the maximum flow rate group, this is mistakenly recognized as the minimum flow rate, and an extreme error occurs. The situation that occurs is avoided.

(Embodiment) FIG. 2 shows an embodiment of the present invention, in which 11 to 14 are fuel injection valves, 15 is a resistor, and 16 is a control circuit.

The fuel injection valves 11 to 14 are selected from one of the groups by dividing a large number of fuel injection valves whose flow rate characteristics have been measured into groups having almost the same flow rate characteristics. In this case, according to the flow rate characteristics, for example, as shown in FIG. 3, the flow rate is divided into three groups, a large flow rate group, a standard group, and a small flow rate group.

The resistor 15 has a predetermined electric resistance corresponding to the flow rate characteristics of the fuel injection valves 11-14.
Is selected as a group having a large flow rate of 1 KΩ, a standard group having ∞ (infinity), and a small group having an electrical resistance of 0 are selected.

The control circuit 16 is composed of a microcomputer including a CPU, a memory, an I / O, etc., and detects the intake air amount of the engine, the number of revolutions, the cooling water temperature, the air-fuel ratio, etc. from each operating state detection means (not shown). The fuel injection amount (injection pulse width) is calculated based on the value, the injection pulse width is corrected according to the electric resistance value of the resistor 15, and an injection pulse signal is output to the fuel injection valves 11 to 14, Control the injection amount.

In this case, the electric resistance value of the resistor 15 is converted into a voltage value by the detection unit 17 provided in the control circuit 16, and the electric resistance value is
A voltage value within 1 to 4 V when 1 KΩ, 4 V or more when ∞, and 1 V or less when 0 is input to the control circuit 16. Also,
18 to 21 are power transistors, and 22 is a connector.

The fuel injection valves 11 to 14 are installed in the intake branch 24 of the engine 23 as shown in FIG. 4, but the resistor 15 is installed near the control circuit 16 (not shown in FIG. 4). Is also good.

Next, the control contents executed by the control circuit 16 will be described with reference to the flowcharts of FIGS.

FIG. 5 is a main routine for calculating the injection pulse width Ti,
The injection pulse width Ti is the sum COEF of the basic injection amount T _P calculated from the intake air amount and the number of revolutions, and each correction coefficient by the cooling water temperature etc.
And the feedback correction coefficient α of the air-fuel ratio and the invalid pulse width T _S are calculated from the above equation (2) (S101 to S10).
Five).

FIG. 6 is a routine for calculating the invalid pulse width T _{S, in} which the voltage correction coefficient DTS from the battery voltage V _{B is changed} from the voltage value V _{I NJID} (corresponding to the electric resistance value of the resistance value 15) of the detection unit 17 to the seventh value. The pulse correction coefficient KV _{I NJ} set as shown in the figure is calculated (S201 to S204). Then, the basic invalid pulse width KTS (ineffective component due to the valve opening characteristic of the fuel injection valve at the reference voltage, etc.) and the invalid pulse width for the voltage correction calculated from the correction coefficient DTS of the battery voltage V _B (KTS-DTS x V _B ), the pulse correction factor KV
_{It is} corrected by _{I NJ} to calculate the invalid pulse width T _S (S20
5, S206). That is, the invalid pulse width T _S is corrected according to the electric resistance value of the resistor 15, that is, the flow rate characteristics of the fuel injection valves 11 to 14.

Then, an injection pulse signal corresponding to the injection pulse width Ti calculated in FIG. 5 is output to the fuel injection valves 11-14.

With such a configuration, when the fuel injection valves 11 to 14 have a large flow rate characteristic, the invalid pulse width T _S is reduced and corrected according to the electrical resistance value of the resistor 15 selected corresponding to the flow rate characteristic. Then, the injection pulse width Ti output to the fuel injection valves 11 to 14 is reduced and corrected. Further, when the fuel injection valves 11 to 14 have a characteristic of small flow rate, the invalid pulse width is determined according to the electric resistance value of the resistor 15 selected corresponding to the flow rate characteristic.
T _S is increased corrected injection pulse width Ti is outputted to the fuel injection valve 11 to 14 is increased corrected.

Therefore, even if the flow characteristics of the fuel injection valves 11 to 14 deviate from the standard, it is possible to always obtain the fuel injection amount required by the engine from the fuel injection valves 11 to 14, and to maintain the operating condition of the engine. It is possible to ensure the optimum fuel injection amount control according to the above. Therefore, for example, it is possible to prevent a delay in air-fuel ratio correction during feedback control of the air-fuel ratio, or a problem during learning due to an error in the injection amount when performing learning control.

On the other hand, when the resistance value of the resistor 15 is infinite, it is determined that the flow characteristics of the fuel injection valves 11 to 14 belong to the intermediate standard group. Even if 15 is dropped due to vibration etc., the fuel injection valve
11 to 14 are determined to belong to the intermediate flow rate group. Therefore, even if the actually installed injection valve has the maximum flow rate or the minimum flow rate, the control error of the fuel injection amount becomes extremely large. Never. Further, since the fuel injection valves 11 to 14 having the same flow rate characteristics are mounted on the engine in group units, even if the resistor 15 is dropped out as described above, all of the injection valves 11
It is possible to reliably control the injection amount of up to 14 within a predetermined error.

In addition, in this embodiment, even an injection valve having a large variation in flow rate characteristics can be used, so that an injection valve with a flow rate adjusting mechanism is not necessary and the total cost can be significantly reduced.

(Effects of the Invention) As described above, according to the present invention, the fuel injection amount is calculated based on the operating state of the engine, and the control means for outputting the injection pulse signal to the fuel injection valve based on the fuel injection amount is provided. In a fuel supply device for an internal combustion engine, a fuel injection valve selected from any one of a plurality of groups of fuel injection valves that are preliminarily divided into groups according to the magnitude of the flow rate characteristic is attached to the engine, and the group of the flow rate characteristic is supported. A resistor having a resistance value, the flow rate characteristic is identified based on the resistance value of the resistor, and correction means for correcting the pulse width of the injection pulse signal with a correction value according to the flow rate characteristic is provided. The correction means is set so that when the resistance value is infinite, the fuel injection valve is regarded as a group of intermediate flow rate characteristics, so that there is a large variation in the flow rate characteristics of the fuel injection valve. Even in such a case, the fuel injection amount can be controlled as required by using such a fuel injection valve, that is, the optimal control of the fuel injection amount according to the operating state of the engine can be performed.

Further, in the present invention, when the resistor is forgotten to be attached or dropped, the fuel injection amount control is performed assuming that the fuel injection valve has an intermediate flow rate characteristic, so that the error of the fuel injection amount becomes extremely large. The effect that it can be avoided is also obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 3 is a flow rate characteristic diagram of a fuel injection valve, and FIG.
FIG. 7 is a layout diagram of fuel injection valves, FIGS. 5 and 6 are flow charts showing control contents, FIG. 7 is a graph showing pulse correction coefficients, and FIG. 8 is a flow rate characteristic diagram of each fuel injection valve. 11 to 14 …… Fuel injection valve, 15 …… Resistor, 16 …… Control circuit

Claims (1)

[Scope of utility model registration request] 1. A fuel supply system for an internal combustion engine, comprising: a control means for calculating a fuel injection amount based on an operating state of the engine and outputting an injection pulse signal to a fuel injection valve based on the fuel injection amount. A fuel injection valve selected from any group of fuel injection valves divided into a plurality of groups according to the magnitude of the flow rate characteristic is attached to the engine, and a resistor having a resistance value corresponding to the group of the flow rate characteristic is provided, Correction means is provided for identifying the flow rate characteristic based on the resistance value of the resistor and correcting the pulse width of the injection pulse signal with a correction value according to the flow rate characteristic, and the correction means has an infinite resistance value. The fuel supply device for the internal combustion engine is characterized in that the fuel injection valve is set to be considered to be a group having an intermediate flow rate characteristic.