JPS6098130A - Fuel injection device - Google Patents

Abstract

PURPOSE:To aim at safety in case of trouble happening in an overflow regulating solenoid valve, by installing a separate overflowing mechanism in addition to the overflow regulating solenoid valve. CONSTITUTION:An overflow regulating solenoid valve 20 is installed in a passage interconnecting a high pressure chamber 10 of a fuel-injection pump to the low pressure side, while as a separate overflowing mechanism, a spill port 51 and a spill ring 52 are installed in a plunger 8 and driven by an actuator 60. Thus even when trouble happens in the solenoid valve 20, this separate overflowing mechanism is operated whereby an injection quantity is limited to the specified value and any danger such as overrunning or the like is preventable from occurring.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fuel injection device for an internal combustion engine,
In particular, it relates to a safety device for preventing overruns in electromagnetic valve spill metering systems.

[Prior art]

Conventionally, as shown in Japanese Patent Publication No. 51-34936, etc., a solenoid valve is provided in a passage communicating between a high-pressure pump chamber compressed by a plunger of a fuel injection pump and a low-pressure side, and the on-off valve of the solenoid valve is connected to an electromagnetic circuit. A so-called ffi magnetic valve spill metering type fuel injection pump has been proposed, which controls the amount of fuel to be injected.

Before explaining the present invention, first of all, the conventional electromagnetic valve spill metering type fuel injection pump (n11) is compared to the well-known Bosch V
An example of application to a distribution type injection pump based on type B will be explained with reference to FIG.

Drive shaft (2) supported by housing (1)
is rotationally driven by an engine (not shown). A known vane type feed pump (4) is integrally connected to the shaft by a key (3) and rotates coaxially with the shaft. Due to the action of the feed pump, fuel flows from a fuel tank (not shown), through a filter (not shown), etc., to an inlet (5).
) from the regulator valve (16) (7
) The pump housing chamber (6
).

Furthermore, a compression and distribution plunger (8) is connected to the drive shaft (2) via a known face cam type pressure feeding mechanism (7).
) are coupled coaxially and integrally in the rotational direction, and reciprocally movable in the axial direction.

The fuel in the housing chamber described above flows into the suction port (9) when the plunger descends (moves to the left in the figure) by a known cam mechanism.
) into the high-pressure pump chamber (10) formed on the end face of the plunger (8), and during the compression stroke by the same cam mechanism, it is compressed to high pressure and the distribution bow () (
11), a passage (12), and a discharge valve (13) before being injected into the combustion chamber of the engine from a nostle (not shown).

When the plunger (8) reaches a predetermined pressure stroke and current is applied to the first coil (21) of the electromagnetic spill valve (20), the magnetic force generated in the stake (22) impinges on the spring (23). The needle (24) is suctioned and the seat part (25) is opened to allow the compressed fuel in the high pressure pump chamber (10) to flow through the passages (26) and (27) into the housing chamber (6). The injection ends with overflow.

The injection timing is controlled by a known hydraulic timer mechanism (30) by changing the phase of the reciprocating movement relative to the rotation of the plunger (8).

(40) outputs a bob rotation angle signal for determining the opening timing of the electromagnetic spill valve (2o).

For example, it is a rotation sensor consisting of a known electromagnetic pickup and a disc-shaped member having a large number of protrusions.

The electromagnetic valve spill metering system described above has the following serious drawbacks.

In other words, in this type of pump, in the unlikely event that the solenoid valve (20)
If the coil of this fuel injection pump is disconnected or a failure occurs in the solenoid valve drive circuit and the solenoid valve is not energized normally and the valve cannot open correctly, the fuel injection pump The fuel compressed in the high pressure pump chamber (JO) is always injected over the entire pumping stroke of the face cam mechanism since there is no other overflow path.

Therefore, an excessive amount of fuel reaching 1.5 to 2 times the maximum injection amount under normal injection amount control is injected regardless of the driver's will, resulting in abnormal exhaust black. This not only produces smoke, but also causes an extremely serious problem in that it becomes impossible to control the engine output and the engine speed reaches an abnormally high speed, resulting in an overrun.

As a means to avoid such serious problems, conventional injection pumps close the intake throttle valve installed in the engine intake pipe, or install a fuel cutoff valve installed in the fuel intake passage to stop the engine. Methods such as closing the valve have been proposed and have even been put into practical use, but the former restricts the intake air.
(2) Extreme tJ as it supplies more fuel than the maximum injection amount to
There is a problem that it emits dark smoke, and in the case of the method described later, the engine stops immediately in the event of an abnormality, making it impossible to drive beyond ζ. Depending on the situation at the site where the abnormality occurs, ζ may not necessarily be a safety measure The problem is that there is a possibility that it will not be possible.

[Purpose of the invention]

The present invention has been made in view of the above problems.

The purpose of the ml of the present invention is to avoid an abnormal increase in fuel injection amount that may lead to engine overrun even in the event of a failure such as disconnection of the electromagnetic spill valve in an injection pump using an electromagnetic valve spill metering method. The goal is to provide safety equipment that can

Furthermore, in a more preferred embodiment of the present invention, even when the safety device is activated, the injection amount of the injection pump is not reduced to zero, and the injection amount can be maintained at a small amount that is possible during low-speed evasive driving. purpose.

Furthermore, another object of the present invention is to use the safety device mechanism to prevent the generation of black smoke at startup when the solenoid valve operates abnormally due to a drop in the electromagnetic brake drive voltage such as during cryogenic startup. The purpose is to make it possible to do both.

(Structure of the Invention) The present invention provides another overflow mechanism in addition to the overflow regulating solenoid valve, and activates the other overflow mechanism when an abnormality occurs in the overflow regulating solenoid valve. Additionally, the fuel injection amount is limited to a predetermined amount.

〔Effect of the invention〕

According to the present invention, even if an abnormality occurs in the overflow regulating solenoid valve, it is possible not only to prevent the generation of abnormal exhaust black smoke, but also to prevent dangers such as engine overrun, and moreover, avoidance driving at low speed. An excellent effect can be obtained in that it is possible to maintain a small amount of fuel injection.

〔Example〕

Hereinafter, the present invention will be explained according to embodiments shown in the drawings.

First, a first embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a cross-sectional view showing the structure of the main parts of the first embodiment of the present invention, and the structure of other parts is omitted because they are the same as the conventional one shown in FIG.

In addition to the structure of the injection pump of the solenoid valve (SPI) metering method already explained in FIG. pump room (10
) at least one spill boat communicating with (51)
and a spill ring (52) that precisely fits into the plunger 4 (8).

Leno (-(53)) is engaged with the spill ring (52),
The lever (53) is supported on a fulcrum (54) and is configured to be rotatable, and is always urged clockwise in the figure by a spring (55) at the other end of the spill ring (52). and p: stopper (61) of full ff (60)
) is positioned by -(positioning).

In this embodiment, a solenoid actuator is used as the safety device actuator (60), and a core (62) made of a magnetic material is integrally attached to the stopper (61). When the coil (63) is energized, the core (62) is attracted by electromagnetic force and moves to the right in the figure, and when the coil (63) is not energized, the core (62) moves to the right in the figure.
4) is pushed to the left in the figure. (65) is a bellows for sealing the light oil in the housing chamber (6) of the fuel injection pump from flowing out without interfering with the reciprocating movement of the stopper (61).

Next, the operation of the first embodiment will be explained. Electromagnetic spill valve (20
) of the safety device (60) during normal operation, the coil (63
) is not energized, and the ′ζ strapper 61) is stationary on the left side of the figure due to the pressing force of the spring (64), and the spring (
55), the lever (53) is positioned by turning around the pin (54) in the direction δ1 when it is dark in the °CC diagram.

As a result, the spill ring (52) that engages with the lever (53) is stationary at a predetermined position on the right side of the figure.

As can be easily understood from the known VE type spill mechanism,
The spill ring (52) is closer to the right in the figure, since the injection amount is increased, so the stopper (6) of the safety device (60)
The maximum injection amount that can be supplied by the injection pump can be arbitrarily set by appropriately determining the coil non-3ffl m M stroke of 1).

In order to achieve only the purpose of this embodiment as a safety device, the spill ring (52) should be set far enough to the right and sufficiently large so as not to affect the injection amount adjustment by the normal solenoid valve (20). It is sufficient to set the maximum injection amount, but it is more preferable to set the maximum injection amount level to the required maximum injection amount when starting the engine. and said electromagnetic spill valve (20
) cannot open or close normally, the spill ring (5
If 1) enables the mechanical maximum injection amount and avoids the generation of abnormal black smoke at startup, secondary effects can be expected.

Next, when an abnormality is detected in the electromagnetic spill valve (20) or its drive circuit, current is passed through the coil (63) of the safety device (60) by an electronic control circuit (not shown), and the stopper (61) ) and the core (62) are attracted to the right in the figure. As a result, the spill ring (52) moves to the left in the figure via the lever (53) to reduce the amount of fuel.

In this case as well, the stroker of the stopper (61) may be optimally determined, and in the event of an abnormality, all of the fuel in the high-pressure pump chamber (10) may overflow from the spill ring, causing no injection at all and stopping the engine. More preferably, the degree of evasive travel from the site of the abnormality occurrence to the nearest repair shop is desirably short so that the smallest possible injection amount can be supplied.

Next, the electronic control circuit (80
) configuration will be explained.

As a simple method, the engine speed is constantly monitored, and if the engine 11j1 rotation speed exceeds the rated maximum engine speed, the solenoid (63) of the safety device (60) is activated.
).

In an even more preferred method, the temperature is as shown in FIG.
Part of the wiring to the electromagnetic spill valve (20) (for example, part 0)
For example, in the case of FIG. 3, the potential of the spill valve (2) is monitored.
When 0) is turned on, the potential of the 0 section drops from the battery voltage to the ground level. Taking advantage of this fact, the monitoring section (83) consisting of a microcomputer etc. adjusts the potential of the 0 section at a predetermined time interval (for example, 5 ms). ), and if the potential of the 0 part remains at a high level continuously for a predetermined period of time (for example, 0.53), the spill (f' (20) or the spill valve drive stage (81), or It may be configured to determine that there is an abnormality in the power transistor (82) or the like and energize the solenoid (63) of the safety device actuator (60).

Note that since it is normal to use an electronic control circuit using a microcomputer to control the injection amount of the fuel injection pump of the electromagnetic valve spill metering method to which the present invention is applied, the abnormality detection shown in FIG. The configuration may be incorporated into the software of the electronic control circuit and part of the software of bar 1'.

Next, a second embodiment of the present invention will be described with reference to diagram m4. What differs from the first embodiment described in FIG. 2 is the configuration of the safety device actuator (70).

In the embodiment of FIG. 4, a diaphragm (72) is integrally disposed on the stopper (71), and the diaphragm (7
2) On both sides, the left side chamber (73) is always supplied with atmospheric pressure through the breathing hole (74), and the right side chamber (75) is connected to the pipe (76), piping (100), and three-way solenoid valve (101). Atmospheric pressure or, for example, negative pressure created by a brake boosting vacuum pump (2) attached to a generator is selectively communicated through the generator.

The control circuit (90) opens the three-way solenoid valve (101) to the atmosphere when the spill solenoid valve (20) is normal, and at this time both ends of the diaphragm (72) are at atmospheric pressure and the stopper (71) is opened. ) are held in a balanced position only by springs (78) and (79). In this state, as explained in the first embodiment, it is assumed that the spill ring (52) is set to match the maximum injection amount.

More preferably, the maximum injection amount can be finely adjusted using the adjustment mechanism 102).

If an abnormality occurs in the spill solenoid valve (20), the control circuit (
90) connects the three-way solenoid valve (101) to j! J is overwhelmingly developed. As a result, the right chamber (75) of the diaphragm (72)
Negative pressure is communicated to the stopper (71), and the stopper (71) moves to the right in the figure, and the spill ring (52) moves to the reduction side via the lever (53) and operates as a safety device to prevent engine overrun.

In this case as well, evasive driving is possible if settings are made so that a small amount of fuel can be injected even when the safety device is activated.

Furthermore, if the time ratio for opening the three-way solenoid valve (101) under negative pressure is controlled by so-called duty ratio, it can be used as a simple governor for backup in case of an abnormality.

Furthermore, in this embodiment, when the safety device is not activated, the injection amount at startup in the event of voltage drop is determined by the spill ring (52), which is a component of the safety device, but recent supercharging etc. In some high-performance engines that undergo heavy supercharging, the maximum injection amount at medium and high speeds exceeds the injection amount at startup, and in this case, the spill mechanism makes it impossible to inject more than the maximum injection amount at startup. occurs. To counter this,
In Fig. 4, if supercharging pressure is connected to the atmosphere side of the three-way solenoid valve (101) instead of atmospheric pressure, the spill mechanism of the safety device will determine the maximum injection according to the increase in supercharging pressure. The upper limit of the fuel injection amount also increases, so that the spill solenoid valve (20) does not inhibit normal fuel injection amount control over the entire engine operating range during normal operation.

Furthermore, in both the first and second embodiments, the safety device was constructed using a well-known spill ring mechanism in the VE type fuel injection pump, but the point is that the overflow is caused by a predetermined stroke of the plunger. Spill the fuel injection amount upper limit regulated by the overflow means and the overflow means! Any device may be used as long as it has a switching means that selectively switches depending on whether the magnetic valve is normal or abnormal.

Further, the actuator of the safety device is not limited to the solenoid or negative pressure servo mechanism disclosed in the embodiments, and any actuator such as a DC motor or a linear solenoid can be used.

Furthermore, FIG. 5 shows a third embodiment, which is the simplest embodiment of the present invention, in which the relief valve (100) is a simple spool-type solenoid valve, and the solenoid valve is always connected to the high-pressure pump chamber (10).
Facing the fuel passages (105) and (103) that communicate with
When the coil (102) of the relief valve (100) is energized in the event of an abnormality, the spool (101) moves to the right in the figure, causing the passage (
103) and (104) are electrically connected to each other so that no injection or a small amount of injection is made.

Although typical embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications are possible.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing a structure related to an improvement of a conventional fuel injection device for an internal combustion engine, and Fig. 2 shows a structure of main parts of a first embodiment of the present invention. The figure is a circuit diagram of the electronic control circuit that controls the safety device of the first embodiment, Figure 4 is a sectional view of the main parts of the second embodiment, and Figure 5 is the main part of the third embodiment. FIG. 3 is a cross-sectional view of the main part showing the structure of the part. 8. Plunger, 10. High pressure pump chamber, 20.
... Solenoid valve for overflow adjustment, 51.52 ... Spill boat and spill ring without separate overflow mechanism, 53 ... Lever, 54 ... Pin, 60.70 ... Safety device actuator , 100...Relief valve forming another overflow mechanism. Representative Patent Attorney Takashi Okabe fl'i Figure 2 Figure 4 Figure 1

Claims (1)

[Claims] (1) An overflow regulating solenoid valve (20) is provided in a passage communicating between a high-pressure pump chamber (10) where fuel is compressed to high pressure by a plunger (8) and a low-pressure side. and the solenoid valve (20)
In the electromagnetic valve spill type fuel injection device, the solenoid valve spill type fuel injection device opens the valve at a predetermined time to cause the high pressure fuel in the high pressure pump chamber (10) to overflow, thereby ending the fuel injection and controlling the fuel injection amount. In addition to the overflow regulating solenoid valve (20), another overflow mechanism is provided, and when an abnormality occurs in the overflow regulating solenoid valve (20), the other overflow mechanism is activated. A fuel injection device characterized in that the fuel injection amount is limited to a predetermined amount. The fuel injection device according to claim 1, which controls the fuel injection amount to be equal to or slightly larger than the rated maximum fuel injection amount at IJ when starting. (3) For mI overflow adjustment. Feature a' [Claim 1 or 2] for increasing the upper limit of the maximum fuel injection amount limited by the separate overflow mechanism when the solenoid valve (20) is normal; 3. The fuel injection device according to any one of paragraphs.