JPH088277Y2 - Electronically controlled fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a fuel injection device for an internal combustion engine in which a fuel injection amount is electronically controlled.

(Prior Art) In a fuel injection pump, a fuel pressurizing chamber is configured to be able to communicate with a low-pressure fuel portion via a solenoid valve, and control of fuel injection can be electronically performed by opening / closing control of this solenoid valve. A fuel injection device is known (Japanese Patent Laid-Open No. 56-154134).

In this type of conventional device, the target fuel injection amount is controlled by the pump plunger once during the valve closing period of the solenoid valve for obtaining the required fuel injection amount calculated based on the operating parameters of the internal combustion engine. Fuel volume per stroke (mm
⁽³ / stroke), the target injection amount data and the engine speed at that time are determined by map calculation, for example, and the solenoid valve opening / closing control is executed according to this determination.

(Problems to be solved by the invention) However, even if the fuel injection device is configured so that the prestroke amount can be adjusted in order to adjust the fuel injection rate and thereby the oil transfer rate can be changed, Even if the injection period is fixed to a fixed value, the fuel injection amount cannot be accurately controlled due to the change in the oil feed rate.

Here, the oil feed rate is defined with respect to the fuel pressure-fed from the fuel injection pump main body. If the diameter of the pump plunger is d and the cam speed of the cam for reciprocating the pump plunger is Vc, then πd Shown in ² Vc / 24 (mm ³ / deg). Therefore, if the prestroke amount is adjusted, the cam speed Vc changes and the oil feed rate can be adjusted.

On the other hand, the fuel injection rate is defined for the fuel injected from the fuel injection nozzle, and is a value (unit: unit of fuel injection amount injected from the fuel injection nozzle over the injection period).
mm ³ / deg), which is the same unit as the oil transfer rate. But,
Even if the oil feed rate is the same, the fuel injection rate is influenced by the injection hole diameter of the injection nozzle, the valve opening pressure, the inner diameter and the length of the injection pipe, etc. Does not necessarily have a value of. Further, in a fuel injection device configured to perform fuel injection control by controlling the opening / closing of a solenoid valve, the fuel injection start timing is determined by the solenoid valve closing timing, so the fuel injection start timing is directly adjusted by adjusting the prestroke amount. Is not affected.

An object of the present invention is to provide an improved electronically controlled fuel injection pump that can solve the above-mentioned problems in the prior art.

(Means for Solving the Problem) A feature of the present invention for solving the above-mentioned problems is that a plunger reciprocated according to a cam profile of a cam member and a high pressure chamber for pressurizing fuel according to the reciprocating motion of the plunger. And a solenoid valve disposed between the high-pressure chamber and the low-pressure fuel section, and an adjusting section for adjusting the fuel feed rate of the fuel pressurizing and pressure-feeding mechanism. And an electromagnetic valve control unit for controlling the opening and closing of the electromagnetic valve for adjusting the pumping start timing and the pumping period of the fuel pressurized by the fuel pressurizing and pumping mechanism. In the injection device, the solenoid valve control unit includes a speed sensor that detects an engine speed for the internal combustion engine, an accelerator sensor that detects an operation amount of an accelerator member, and at least the speed sensor and an accelerator sensor. A target amount output unit for outputting a target amount signal indicating a target amount of fuel to be injected in response to a xcel sensor; and a first indicating a closing period of the solenoid valve corresponding to the target amount in response to the target amount signal. A signal generator that outputs a signal, an output unit that outputs an adjustment amount signal indicating an adjustment amount by the adjustment unit, the speed sensor and a valve closing period corresponding to the prestroke value at that time in response to the adjustment amount signal. A correction signal generation unit that outputs a correction signal indicating a correction amount, and a correction unit that outputs a second signal that is responsive to the first signal and the correction signal and that corrects the first signal based on the correction amount. Means for outputting a target timing signal indicating an injection start timing of fuel to be injected in response to at least the speed sensor and the accelerator sensor; and a means for responding to the second signal and the target timing signal, An output unit that outputs a signal for controlling the opening and closing of the solenoid valve so as to shut off the high pressure chamber from the low pressure fuel portion for the valve closing period indicated by the second signal from the injection start timing indicated by the target timing signal. It is equipped with and.

(Operation) The target amount output unit outputs a target amount signal indicating the target injection amount according to the operating state. The signal generator outputs a first signal indicating a valve closing period of the solenoid valve corresponding to a given target injection amount.

From the correction signal generation unit, the valve closing period correction amount according to the adjustment amount at that time of the adjustment unit, that is, the valve closing amount to be increased or decreased when the fuel is pressurized and pumped at the oil feed rate based on the adjustment amount at that time A correction signal indicating the period value is output.

The first signal is corrected by the correction unit by the increase / decrease value according to the correction signal, and the second signal indicating the corrected valve closing period is output.

A signal for performing opening / closing control of the solenoid valve is provided from the output unit so as to shut off the high pressure chamber from the fuel low pressure portion for the corrected closing period indicated by the second signal from the injection start timing indicated by the target timing signal. Is output.

As a result, the closing period of the solenoid valve that regulates the fuel injection amount is corrected in consideration of the oil feed rate at that time, so no matter how the oil feed rate is set by the adjustment unit, the fuel is set according to this setting state. The control accuracy of the injection amount does not decrease.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a distributed fuel injection device. This fuel injection device 1
Is used in combination with an internal combustion engine (not shown), is electronically controlled as described later, supplies fuel to each cylinder of the internal combustion engine, and includes an injection pump 2.

The injection pump 2 has a vane pump 4 and a roller holder 5 which are connected to a drive shaft 3 which is rotationally driven at a rotation speed related to the rotation speed of the internal combustion engine. The vane pump 4 pressurizes the fuel supplied from a fuel tank (not shown) through the passage 6, and sends the pressurized fuel to the passage in the housing 7. One end of the drive shaft 3 extends into the housing chamber 9, and the cam disk 11 is a dry bin disk 10.
Is connected to one end of the drive shaft 3 via. The plunger 12 has a plunger spring on one side of the cam disk 11.
It is pressed by 13 and the plunger 12 is in the housing 7.
It is fitted in the cylinder portion 14 formed in the. As a result, according to the rotation of the drive shaft 3, the plunger 12 rotates and simultaneously reciprocates.

At the mating end of the plunger 12, intake slits 15 are formed in a number corresponding to the number of cylinders of the internal combustion engine.
Only one of the four intake cuts is shown in the figure. In the descending stroke of the plunger 12, when the intake port 16 formed at the end of the passage 8 and one of the intake slits overlap each other, the passage 8
The pressurized fuel sent by is sucked into the high pressure chamber 17 formed by the cylinder portion 14 and the plunger 12. The fuel sucked into the high-pressure chamber 17 begins to be pressurized by the cam lift operation after the intake port 16 is closed by the rotary lift operation of the plunger 12.

The passage 18 formed in the plunger 12 communicates with the distributor slit 19.When the distributor slit 19 overlaps with the outlet passage 20 as the plunger 12 continues the rotary lift, the pressurized high pressure fuel is delivered to the delivery valve 21. To the pipe 22 connected to an injection nozzle (not shown).

This injection pump 2 is arranged between the high pressure chamber 17 and the low pressure part of the fuel in the fuel injection device in order to start and end the fuel injection at a desired timing regardless of the position of the plunger 12. A solenoid valve 24 is provided. In the illustrated embodiment, one port of the solenoid valve 24 communicates with the high pressure chamber 23 through the passage 23, and the other port communicates with the fuel tank (not shown) through the passage 28.

The solenoid valve 24 includes a valve body 26 that is movably housed in a cylinder chamber 27 and is constantly pushed upward by an explosion spring 29. The valve body 26 is positioned so that the passages 23 and 25 are in communication when the exciting coil 30 is deenergized, and the solenoid valve 24 is opened. On the other hand, the exciting coil 30
Is biased, the valve body 26 moves against the force of the spring 29,
The opening end of the passage 23 on the cylinder chamber side is closed by the side wall of the valve body 26, and the electromagnetic valve 24 is closed. As can be seen from the above description, the high pressure chamber 17 can be operated only when the solenoid valve 24 is closed.
It is possible to pressurize the fuel inside.

Reference numeral 40 is a pre-stroke adjusting mechanism configured similarly to the conventional hydraulic timer device, in order to set the pre-stroke value to a desired value by adjusting the lift start timing of the plunger 12. It is provided. The prestroke adjusting mechanism 40 includes a piston 42 that is urged by a spring 41 so that the pressure in the passage 8 is applied to the piston 42 through a throttle 43. An electromagnetic pressure control valve 44 is provided for the purpose of adjusting the fluid pressure acting on the piston 42 and positioning the position of the piston 42 at a desired position, and the opening degree of the pressure control valve 44 is adjusted. As a result, the pressure in the cylinder chamber 45 can be set to a desired value.

The piston 42 is articulated to the other end of a rod 46, one end of which is connected to the roller holder 5,
According to the position of 42, the angular position of the roller holder 5 is changed so that the prestroke amount is adjusted.

When the prestroke value is adjusted as described above, the usage area of the cam surface of the cam disk 11 for reciprocating the plunger 12 changes. Therefore, even if the fuel injection start timing adjusted by the solenoid valve 24 independently of the adjustment of the prestroke value is fixed to a constant value,
When the pre-stroke value is adjusted, the oil feed rate changes, which allows the fuel injection rate to be adjusted. That is, in this embodiment, this prestroke adjusting mechanism is used as an oil feeding rate adjusting mechanism, and cooperates with a prestroke control unit 55 described later to control the oil feeding rate according to the operating state of the engine. Done. Note that the relationship between the oil feed rate and the fuel injection rate is as described above.

In order to electronically control the fuel injection pump 2 configured as described above, the fuel injection device 1 includes an electronic control unit 50.

The electronic control unit 50 includes an accelerator sensor 52 that outputs an accelerator signal A that indicates the amount of operation of the accelerator pedal 51, and a speed sensor 5 that outputs a speed signal N that indicates the engine rotation speed of the internal combustion engine.
3, and a position sensor 54 that outputs a position signal P indicating the position of the piston 42 as a signal indicating the adjustment amount of the prestroke adjusting mechanism 40.

Reference numeral 55 indicates a prestroke control for controlling the opening degree of the pressure regulating valve 44 in response to the accelerator signal A and the speed signal N so as to give a prestroke amount corresponding to the operating state of the internal combustion engine at that time. It is a unit. From the pre-stroke control unit 55, a pulse signal having a duty ratio necessary for setting the opening degree of the pressure adjusting valve 44 to a required value is output as a pre-stroke control signal Sa, and the pre-stroke control signal Sa is the pressure control valve. 44 excitation coils 44
Applied to a, the opening degree of the pressure adjusting valve 44 is adjusted according to the duty ratio of the prestroke control signal Sa.

The accelerator signal A and the speed signal N are also input to the target value calculation unit 56, where the target value of the fuel injection amount that matches the operating conditions of the internal combustion engine at that time is calculated, and the fuel injection obtained as the result of this calculation is calculated. A signal indicating the amount is output as the target signal T, and is input to the solenoid valve control unit 60 to which the accelerator signal A, the speed signal N and the position signal P are separately input.

The solenoid valve control unit 60 is for controlling the opening and closing of the solenoid valve 24 for the purpose of controlling the injection timing and the injection amount of the fuel injected by the fuel injection pump 2, and the solenoid valve control unit 60 responds to each input signal. A drive control signal C for controlling the opening / closing of 24 is output.

Next, the solenoid valve control unit 60 will be described with reference to FIG.

The effective injection angle calculation unit 61 responds to the target signal T and the speed signal N, and is an effective injection angle that is the rotation angle of the cam required to obtain the target injection amount indicated by the target signal T based on predetermined map data. EA is calculated and the result is output as the first signal S1 indicated by the cam angle. Even if the solenoid valve 24 is closed only during the effective injection angle period indicated by the first signal S1, the solenoid valve control unit 60 considers that the amount of fuel actually injected increases or decreases depending on the engine speed and the prestroke value. Is provided with a correction signal generator 62 for calculating the correction amount of the effective injection angle for making the increase / decrease amount zero. The correction signal generator 62 is responsive to the speed signal N and the position signal P, and the map calculation is based on map data indicating a known relationship between these signals and the fuel increase / decrease amount. Executed in. Then, the correction signal H indicating the angle value for correcting the effective injection angle according to the increase / decrease amount obtained by this map calculation is output.

The correction unit 63 corrects the first signal S1 based on the correction signal H so as not to actually cause the increase / decrease amount calculated by the correction signal generation unit 62 in response to the first signal S1 and the correction signal H. Then, the second signal S2 is output. Therefore, the injection angle indicated by the second signal S2, that is, the solenoid valve
The valve closing period of 24 is a control value of the solenoid valve 24 that actually gives the injection amount indicated by the target signal T at the engine speed and the prestroke amount at that time.

Reference numeral 64 indicates a speed signal and an accelerator signal A.
Is a fuel injection timing calculation unit for calculating the fuel injection timing suitable for the operating condition indicated by, and the target injection timing signal TI indicating the fuel injection timing calculated here is a pulse to which the second signal S2 is input. It is input to the generation circuit 65.

The rotation pulse P1 is input to the pulse generation circuit 65 from the rotation pulse generator 66 every time a crankshaft (not shown) of the internal combustion engine rotates by a predetermined angle, and the crankshaft reaches a predetermined rotation position. Then, the reference pulse P2 is input from the reference pulse generator 67. The reference pulse generator 67 can be configured such that the reference pulse P2 is output, for example, at the timing when the piston of a predetermined cylinder of the internal combustion engine reaches its compression top dead center.

The pulse generation circuit 65 controls the opening / closing of the solenoid valve 24 based on the timing information indicated by the rotation pulse P1 and the reference pulse P2 and according to the target information regarding the fuel injection amount and the injection timing indicated by the second signal S2 and the target injection timing signal TI. The drive control signal C, which is a pulse signal for, is output. That is, the electromagnetic valve 24 is closed at the timing indicated by the target injection timing signal TI to shut off the high pressure chamber 17 from the low pressure portion to start the fuel injection, and the second signal S2
The drive control signal C for controlling the opening and closing of the solenoid valve 24 so as to maintain the closed state of the solenoid valve 24 only during the period corresponding to the injection angle indicated by It is controlled to open and close.

According to such a configuration, in the case where the prestroke amount is adjusted in the fuel injection pump 2 by the prestroke adjusting mechanism 40, even if the oil feeding rate changes due to the adjustment, the correction signal generating unit 62. The first signal S1 is corrected by the correction signal H that is output at, and the second signal indicating the injection angle at which the target injection amount indicated by the target signal T is obtained in the prestroke amount at that time is input to the pulse generation circuit 65. To be done. As a result, the opening / closing control of the solenoid valve 24 is executed so that the target injection amount determined by the target value calculation unit 56 is obtained irrespective of the prestroke adjustment amount, so that the fuel injection amount can be controlled extremely accurately. can do.

In the above embodiment, the speed sensor 53 shown in FIG. 1 can be configured to detect the engine speed using the rotation pulse P1 from the rotation pulse generator 66 shown in FIG. Of course.

(Effects of the Invention) According to the present invention, as described above, even if the oil feed rate is adjusted by the adjusting unit to adjust the fuel injection rate, the closing period of the solenoid valve that regulates the fuel injection amount is set at that time. Since the correction is made in consideration of the oil rate, it is possible to effectively prevent the control accuracy of the fuel injection amount from decreasing due to this setting state, regardless of how the oil transfer rate is set by the adjustment unit. The control accuracy of the fuel injection amount in the injection device can be significantly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
It is a detailed block diagram of the solenoid valve control unit shown in the figure. 1 ... Fuel injection device, 2 ... Fuel injection pump, 12 ... Plunger, 17 ... High pressure chamber, 24 ... Solenoid valve, 40 ... Pre-stroke adjustment mechanism, 56 ... Target value calculation unit, 60 ... Solenoid valve control unit, 61 ... Effective injection angle calculation unit, 62 ... Correction signal generation unit, 63 ... Correction unit, 65 ... Pulse generation circuit, T ...
… Target signal, S1 …… First signal, S2 …… Second signal, C ……
Drive control signal.

Claims (1)

[Scope of utility model registration request] 1. A fuel pressurizing and feeding mechanism comprising a plunger reciprocally moved according to a cam profile of a cam member and a high pressure chamber for pressurizing fuel according to the reciprocating movement of the plunger, the high pressure chamber and the fuel. An electromagnetic valve disposed between the low pressure portion, an adjusting portion for adjusting the fuel feeding rate of the fuel pressurizing and pressure feeding mechanism, and a pressure feeding start of the fuel pressurized by the fuel pressurizing and pressure feeding mechanism. An electronically controlled fuel injection device for an internal combustion engine, comprising: an electromagnetic valve control unit that controls the opening and closing of the electromagnetic valve to adjust timing and a pumping period, wherein the electromagnetic valve control unit is an engine for the internal combustion engine. A speed sensor for detecting a speed, an accelerator sensor for detecting an operation amount of an accelerator member, and an eye indicating a target amount of fuel to be injected in response to at least the speed sensor and the accelerator sensor. A target amount output unit that outputs a reference amount signal, a signal generator that responds to the target amount signal, and outputs a first signal indicating a valve closing period of the electromagnetic valve corresponding to the target amount, and an adjustment amount by the adjustment unit. An output unit that outputs an adjustment amount signal indicating, a correction signal generation unit that outputs a correction signal indicating a correction amount of the valve closing period in response to the speed sensor and the adjustment amount signal according to the prestroke value at that time, A correction unit that outputs a second signal that is responsive to the first signal and the correction signal and that is obtained by correcting the first signal based on the correction amount, and injects in response to at least the speed sensor and the accelerator sensor. For outputting a target timing signal indicating the injection start timing of the fuel to be injected, and an injection start timing indicated by the target timing signal in response to the second signal and the target timing signal. To an output unit for outputting a signal for controlling the opening and closing of the electromagnetic valve so as to shut off the high pressure chamber from the low pressure fuel unit for the valve closing period indicated by the second signal. Electronically controlled fuel injection device.