JPS61275542A - Fuel injection quantity control device - Google Patents

Abstract

PURPOSE:To achieve the reduction in burning noise by controlling the valve closing timing of a solenoid valve for overflowing fuel at the pressurizing stroke of the plunger of a fuel injection pump at the time of idle or low load operation so as to reduce the fuel injection rate. CONSTITUTION:In the subject device, a solenoid valve M6 is interposed in a fuel releasing passage M5 which communicates a fuel pressurization chamber M4 in a plunger pump M3 having a plunger M2 freely capable of reciprocally moving in the axial direction of a fuel injection pump M1 to the low-pressure side, and the fuel injection quantity is controlled by controlling the fuel overflow ing quantity by the open/shut operation of this solenoid valve M6. IN the above, the control circuit M7 of the solenoid valve M6 is so constituted that, in the period of time in which an operating condition discriminating means S1 descriminates the operation to be in a specific operating condition such as an idle condition or low-load operating condition, the valve closing timing of the solenoid valve M6 during forward movement of the plunger M2 is deter mined, and in the other discriminating period of operating condition the valve opening timing of the solenoid valve M6 during the forward movement of the same is determined by a setting means S2.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is applied to a diesel engine.
In a fuel injection amount i control device equipped with an RA valve spiel metering type fuel injection pump, combustion noise is reduced by setting the closing timing of the electromagnetic valve during forward movement of the plunger during engine idling or low load operation. This relates to the fuel injection amount side W device.

[Prior Art] Conventionally, as a measure to reduce combustion noise during idling operation of a diesel engine, for example, Japanese Patent Laid-Open No. 57-5
6631@, as disclosed in Japanese Unexamined Patent Publication No. 57-97024, the pressurizing operation of the plunger of the plunger pump inside the fuel injection pump, that is, the rate of change in the axial movement amount in one forward movement is large in the first half and small in the second half. Focusing on this, a proposal has been made to inject fuel by half the forward movement of the plunger during idle, or in other words, to set the fuel injection rate smaller than during other engine operations. In this proposal, in order to switch the fuel injection rate, an electromagnetic actuator is specially provided to adjust the fuel injection start timing.

By the way, as a means of controlling the fuel injection amount ill ml, a plunger similar to the above is used, and a fuel relief passage is provided, one end of which communicates with the fuel pressurizing chamber of the plunger pump, and the other end of which communicates with the low pressure side (fuel reservoir). The fuel injection pump is equipped with a so-called solenoid valve spill metering system, which is equipped with a solenoid valve that opens and closes this passage, and the valve opening timing of the solenoid valve in the pressurizing stroke of the plunger, that is, the fuel injection pump. It has been proposed to control the fuel injection amount each time by adjusting the injection end timing.

This type of proposal is, for example, JP-A-58-187537, JP-A-5G-200045, JP-A-59-2214.
This is shown in Publication No. 32, etc.

[Problems to be Solved by the Invention] The present invention is a fuel injection amount control device equipped with a fuel injection pump of an electromagnetic valve spill metering type, and in which an electromagnetic actuator for switching the fuel injection rate as described above is specially provided. The aim is to reduce combustion noise during idle or low load operation.

Means for Solving Problem E] To achieve the above object, the present invention provides a fuel injection pump M1 for injecting pressurized fuel into a diesel engine, as schematically shown in FIG. 1. A plunger pump M3 having a plunger M2 that reciprocates without becoming uniform in the rate of change in the amount of axial movement during work, one end of which communicates with the fuel pressurizing chamber M4 of the plunger pump M3, and the other end of which is on the low pressure side. A fuel injection amount 1lIII device comprising a fuel relief passage M5 communicating with a fuel relief passage M5, a solenoid valve M6 that opens and closes this passage M5, and a control circuit M7 that controls opening and closing of the solenoid valve M6, The control circuit M7 is connected to an operating state determining means S1 for determining whether the operating state of the diesel engine is an idle state or a low load operating state.
During the period during which the determining means S1 determines that the specific operating state is present, the closing timing of the electromagnetic valve M6 during forward movement of the plunger is determined, and other operating states are determined. The present invention is characterized in that it is configured to include a solenoid valve opening/opening timing setting means S2 that determines the opening timing of the solenoid valve M6 during the forward movement during the same period.

[Function] With the above configuration, the valve closing timing of the solenoid valve, that is, the fuel injection start timing is controlled in the pressurizing stroke of the plunger during idling or low load operation.
Fuel injection is performed during a portion of the pressurization stroke in which the rate of change in the axial movement of the plunger is small; in other words, the injection rate is small, and therefore combustion noise can be reduced.

[Implementation row] An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 2 and 3, a drive shaft 1 driven by an engine (not shown) rotates a vane-type feed pump 2, which introduces fuel from an inlet 3 and pressurizes the fuel. The fuel is regulated to a predetermined pressure through a fuel pressure regulating valve 4 and is supplied to a fuel chamber 6 formed in an immersion pump housing 5. The drive shaft 1 drives a pumping plunger 8 via a coupling 7. The coupling 7 rotates the pressure-feeding plunger 8 integrally in the rotational direction, but allows the pressure-feeding plunger 8 to freely reciprocate in the axial direction. A face cam 9 is integrally provided on the pressure feeding plunger 8. The face cam 9 is pressed by a spring 10 and pressed against a cam roller 11. Due to these sliding contacts, the cam crest of the face cam 9 rides on the cam roller 11, and the plunger 8 is reciprocated a number of times in accordance with the number of cylinders during one rotation. The pressure-feeding plunger 8 is connected to the housing 5
A pressurizing chamber 13 is configured by being fitted into a head 12 fixed to the pressurizing chamber 13 . Suction grooves 14, .
Fuel is introduced into the pressurizing chamber 13 from the pressurizing chamber 13. When the fuel in the pressurizing chamber 13 is compressed during the pressurizing stroke of the pressurizing plunger 8, the fuel is sent from the distribution port 16 through the pressurizing valve 17 to an injection nozzle (not shown) of each cylinder, and is injected into the combustion chamber of the engine. . A fuel metering mechanism 20 is connected to the pressurizing chamber 13 . In this fuel metering mechanism 20, when a current is applied to the coil 22 of the closed electromagnetic valve 21, the needle valve 23 is lifted, and the fuel in the pressurized chamber 13 is discharged into the fuel relief passage, that is, I
The structure is such that the fuel is returned to the fuel chamber 6 through i-flow paths 24 and 25. Therefore, when the solenoid valve 21 is operated during the pressurizing stroke of the pressure-feeding plunger 8, fuel injection ends. Furthermore, when the current flowing through the coil 22 of the solenoid valve 21 is cut during the pressurization stroke of the plunger w8, the needle valve 23 returns to its original closed state, and the fuel in the pressurization chamber 13 is pressurized by the plunger 8. It is configured so that the pressure starts. Therefore, when the electromagnetic valve 21, which has been in the operating state until then, is deactivated during the pressurizing stroke of the plunger 8, fuel injection starts.

Here, the start timing and end timing of energization to the solenoid valve 21 are determined by a control circuit such as a microcomputer, that is, an electronic control unit W126.

The electronic Ill II device 26 is based on input signals of engine operating conditions detected by various sensors of the engine, such as an engine rotation sensor, an accelerator pedal sensor, and a temperature sensor, and an input signal from a plunger bottom dead center detector as described later. Then, a logical function deduces an output signal and sends this output signal to the coil 22 of the solenoid valve 21. Therefore, the solenoid valve 21 opens and closes in response to the output signal of the electronic control device 26.

The cam roller 11 is held by a roller ring 27.

This roller ring 27 is operated by a fuel injection timing adjustment mechanism 30 (timer). Fuel injection timing adjustment mechanism 3
0 is equipped with a timer piston 31, the fuel pressure of the fuel chamber 6 acts on one end surface of the timer piston 31, and the pressing force of a spring 32 acts on the other end surface of the timer piston 31. It moves in the left-right direction in FIG. 2 due to the fuel pressure in the chamber 6. timer piston 31
The reciprocating movement of is transmitted to the roller ring 27 via the bin 33, causing the roller ring 27 to rotate. Therefore, the sliding contact timing between the cam roller 11 and the seventh eighth cam 9 is shifted, so that the phase of the reciprocating motion of the pressure-feeding plunger 8 with respect to the drive shaft 1 changes, and the fuel injection timing changes. Although the fuel injection timing adjustment mechanism 30 in FIG. 2 is actually provided in a direction in which the axial direction of the timer piston 31 is perpendicular to the plane of the drawing, it is shown as shown in FIG. 2 for illustration purposes.

For example, an electromagnetic pickup 35 is attached to the roller ring 27.
are integrally attached to the drive shaft 1, and a balsa 36 is attached to the drive shaft 1. When one of the protrusions 378 to 37d formed on the balsa 36 crosses the electromagnetic pickup 35 due to the rotation of the drive shaft 1, the electromagnetic pickup 35
generates a signal and sends this signal to the electronic control unit @26. In the electronic control device 26, upon receiving the output signal from the electromagnetic pickup 35, the electromagnetic valve 2 is activated after a predetermined time.
The operation command signal or operation stop command signal No. 9 is output to No. 1.

The radial phase of each of the protrusions 37a to 37d is set correctly so as to coincide with each bottom dead center of the pumping plunger 8.

When the roller ring 27 is rotated by the operation of the timer 30, the electromagnetic pickup 35 is also rotated in the same phase as the roller ring 27.

The electronic control unit 26 executes processing as shown in the flowchart of FIG.

This processing is executed every time a reference pulse train, that is, a reference signal obtained by subjecting the signal generated by the electromagnetic pickup 35 to appropriate processing such as waveform shaping, is input.

(1) First, import data representing engine operating conditions such as accelerator opening and engine speed (Step 1)
01).

(2) Next, based on the captured data, it is determined whether the engine is idling or operating at low load (step 102).

(3a) If it is determined that the operation is not idling or low load operation, the coil 2 of the solenoid valve 21
In step 103a), the rotation angle θ corresponding to the fuel injection amount is determined based on the data representing the operating state.
In step 104a), it is determined whether the plunger rotation angle with reference to the plunger rotation angle position corresponding to the input time of the reference signal is greater than or equal to the rotation angle 01.Step 105a), when the rotation angle is greater than or equal to 01. If it is determined that this has occurred, energization to the coil 22 of the solenoid valve 21 is started (step 106a).

(3b) On the other hand, if it is determined in step 102 that it is idle or low load operation, start energizing the coil 22 of the solenoid valve 21.Step 103b)
, Calculate the rotation angle θ2 corresponding to the fuel injection amount using the data representing the operating state (Step 104b), when the plunger rotation angle based on the plunger rotation angle position corresponding to the input time of the reference signal is equal to or larger than the rotation angle 82. In step 105b), it is determined whether the rotation angle is 0.
2 or more, the coil 22 of the solenoid valve 21
(step 106b).

In this way, the electronic II all device 26 determines whether the engine is idling or operating under low load, and if it determines that the engine is in this specific operating state, it immediately opens the solenoid valve 21 and After a calculated predetermined period of time has elapsed, the valve is closed again. Therefore, with respect to the reference signal having the correspondence as shown in FIG. The opening and closing operations as shown in the figure are performed, and the fuel injection rate is also as shown in FIG.

In addition, if it is determined that the operating state is other than the specific operating state, contrary to the case where it is determined that the specific operating state is present, the solenoid valve 21 is immediately opened, and the valve is opened after a predetermined period of time has elapsed. Let them do it. Therefore, with respect to the reference signal, plunger axial movement amount, and plunger movement volume having the correspondences as shown in FIG.
The opening and closing operations as shown in the figure are performed, and the fuel injection rate becomes as shown in FIG. 6 as well.

As is clear from a comparison of FIG. 5 and FIG. 6, in the specific operating state, fuel injection
vI! In the other operating states, the operation is performed in the first half of the forward movement of the plunger, that is, in the portion where the rate of change in the axial inner diameter is large. The fuel injection rate in the operating state is reduced, thus making it possible to reduce combustion noise.

[Effects of the Invention] As explained above, according to the present invention, during idling or low load operation, the opening timing of the solenoid valve for fuel overflow is changed to reduce the fuel injection rate. , combustion noise can be reduced without special provision of an electromagnetic actuator for switching the injection rate.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing the features of the present invention, Figures 2 to 6
The drawings show one embodiment of the present invention, Fig. 2 is an overall configuration diagram including a sectional view of the fuel injection pump, and Fig. 3 is an
- An X-ray sectional view, FIG. 4 is a flowchart showing the processing of the electronic control device, that is, a control circuit, and FIGS. 5 and 6 are timing factors for explaining the operation of this embodiment, respectively. 6...Fuel reservoir (fuel chamber) 8...Plunger 13
... Fuel pressurization chamber 21 ... Solenoid valve 24.25
・・・Fuel relief passage

Claims (1)

[Scope of Claims] 1. A fuel injection pump that injects pressurized fuel into a diesel engine, the plunger pump having a plunger that reciprocates without making the rate of change in axial movement amount uniform during one forward movement. , a fuel relief passage having one end communicating with the fuel pressurizing chamber of the plunger pump and the other end communicating with the low pressure side, and a solenoid valve for opening and closing this passage; and a solenoid valve for opening and closing the solenoid valve. A fuel injection amount control device comprising: a control circuit for controlling the control circuit;
The determining means determines the closing timing of the solenoid valve while the plunger is moving forward during a period in which it is determined to be in the specific operating state, and determines the closing timing of the solenoid valve while the plunger is moving forward. 1. A fuel injection amount control device comprising a solenoid valve opening/closing timing setting means for determining the opening timing of the solenoid valve during operation.