JPS6023470Y2 - Diesel engine fuel injection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for a diesel engine, and particularly to one in which the fuel injection timing and injection amount are corrected at high altitudes.

-In R9t, in diesel engines, when the atmospheric pressure decreases at high altitudes, the amount of intake air decreases and the amount of fuel increases relatively, causing the air-fuel ratio to become over-rich, which can lead to the generation of smoke, so this is prevented. In order to do this, for example, as disclosed in Japanese Patent Application Laid-Open No. 55-3757, the movement of the governor lever is regulated by a pressure detection member such as a bellows that displaces in response to fluctuations in atmospheric pressure in the fuel injection device. An injection amount control device is provided to control the maximum injection amount of fuel, and the operation of the injection amount control device causes the fuel injection amount to be reduced when atmospheric pressure decreases.

On the other hand, when the atmospheric pressure decreases, the ignitability is impaired due to the decrease in the air filling amount due to the decrease in air density, resulting in a delay in ignition.As a result, the combustion state becomes unstable due to half-misfire, resulting in a decrease in output, etc. Therefore, it is also necessary to advance the fuel injection timing when atmospheric pressure decreases.

Incidentally, a fuel injection device for a diesel engine is usually equipped with an injection timing control device that controls the fuel injection timing based on the fuel pressure in the fuel chamber, which changes depending on the engine speed. In order to achieve this, when the engine is under low load, the fuel in the fuel chamber is discharged through the return passage to lower the fuel pressure in the fuel chamber, thereby correcting the fuel injection timing by the injection timing control device to the delayed side. It is common practice to provide an injection timing correction device that does this.

In a fuel injection device equipped with such an injection timing correction device, there is a problem that when atmospheric pressure decreases, the fuel injection timing tends to be delayed too much, making it impossible to ensure engine output performance.

For this reason, in order to ensure the output performance of the engine even if it sacrifices the emission performance etc. to some extent, the practical application
As No. 156545, a pressure detection member separate from the pressure detection member equipped in the injection amount control device is provided, and the pressure detection member is connected to a solenoid valve that controls opening and closing of the return passage. We have proposed a system in which the return passage is closed using a solenoid valve to reduce the amount of delay in fuel injection timing.

However, this proposal requires separate pressure detection members and electromagnetic valves, resulting in increased cost, complicated structure, and lack of reliability.

In view of this, the present invention utilizes the pressure detection member of the injection amount control device that corrects the fuel injection amount at high altitudes, and directly determines the injection timing by using a member that is connected to the pressure detection member and is directly driven by the pressure detection member. In order to suppress the operation of the correction device, in other words, in the return passage of the injection timing correction device,
By providing a valve mechanism that is mechanically driven by the pressure detection member of the injection timing control device to control the fuel flow rate in the return passage, and reducing the amount of delay in the fuel injection timing when atmospheric pressure decreases, It is an object of the present invention to provide a fuel injection device for a diesel engine in which the fuel injection timing can be corrected for high altitude using a single pressure detection member.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows a first embodiment of the present invention, in which 1 is a pump housing of a fuel injection pump A, 2 is a fuel chamber formed in the housing 1, and 3 is a drive shaft (FIG. 1) rotating in synchronization with the engine. 4 is a regulating valve that adjusts the pressure generated by the feed pump 3 to be proportional to the engine speed, and the feed pump 3 and the regulating valve 4 are attached to the feed pump (not shown) and generate fuel pressure. 4, the fuel chamber 2 is configured to generate a fuel pressure that varies depending on the engine speed.

Although not shown, the fuel injection pump A is equipped with an injection timing control device including a timer piston, which operates the timer piston by applying the fuel pressure in the fuel chamber 2 to the timer piston. Through the operation of the piston, reciprocating motion for sucking and pumping fuel and rotation for distributing fuel are performed based on the drive of the drive shaft.By changing the rotation angle of the plunger relative to the drive shaft, the fuel injection timing can be adjusted. is configured to control.

Reference numeral 5 denotes a centrifugal cuff flyweight mechanism, and the flyweight mechanism 5 is rotatably supported by a governor shaft 5a fixed to the housing 1, and includes a flyweight holder 5c that is rotationally driven by the drive shaft via a governor gear 5b. , governor weights 5d, 5d, ... incorporated in the flyweight holder 5c, and a governor sleeve 5e slidably attached to the governor shaft 5a, and the governor weights 5d, 5d are generated by centrifugal force. The governor sleeve 5e is slid by the expansion operation of , . The fuel injection amount is adjusted according to the engine speed.

Reference numeral 7 denotes an injection timing correction device, which is connected to the suction side of the fuel chamber 2 and the feed pump 3 through a hole 8 formed in the governor sleeve 5e of the centrifugal cuff flyweight mechanism 5. A fuel return passage 7 that communicates with
a, and when the engine is under low load, the return passage 7a is opened by opening the hole 8 by moving the governor sleeve 5e to the right in the figure, and the fuel in the fuel chamber 2 is drained through the return passage 7a. By discharging the fuel and lowering the fuel pressure within the fuel chamber 2, the fuel injection timing is delayed.

Air holes 9a, 9a are provided on the outer surface of the earthen wall of the housing 1.
An atmospheric chamber 10 is formed, which is covered with a cover 9 having a structure, and a pressure detection member 11 made of a bellows that expands and contracts in response to fluctuations in atmospheric pressure is suspended from the lower surface of the cover 9 and disposed within the atmospheric chamber 10. The upper end of an adjusting pin 12 that passes through the housing 1 and moves up and down is attached to the lower end of the pressure detection member 11. ) is formed with a tapered surface 13 constituting a cam surface, and the upper end of a U-shaped correction lever 14 that is pivotally supported on the housing 1 is in sliding contact with the tapered surface 13. The lower end of the governor lever 17 includes a collector lever 15 pivotally supported by the housing 1 and a tension lever 16 coaxially supported by the collector lever 15 with the start lever 6.
6, and the adjusting pin 12 and the correction lever 14 are in contact with the adjusting pin 12 and the correction lever 14 due to the expansion and contraction displacement of the pressure detection member 11.
An injection amount control device 18 is configured to regulate the movement of the governor lever 17 via the starter lever 6, and to control the maximum injection amount of fuel via the start lever 6.

Furthermore, the fuel return passage 7 of the injection timing correction device 7
A valve number storage chamber 19 is formed in a portion of the injection amount control device 18 near the correction lever 14 in the middle of point a, and an outlet port 19b thereof is opened and closed with a tapered tip in the valve storage chamber 19. A valve body 20 to be adjusted is biased in the valve opening direction by a spring 21 and housed, and the rear end of the valve body 20 is attached to the housing 1.
The correction lever 14 is pivoted through the upper end of the correction lever 14, and is therefore connected to the pressure detection member 11 of the injection amount control device 18 and is directly driven by the pressure detection member 11 to control the return of the injection timing correction device 7. A valve mechanism 22 is configured to control the fuel flow rate in the passage 7a.

When the atmospheric pressure decreases, the valve mechanism 22 is closed to prevent the fuel pressure within the fuel chamber 2 from decreasing, suppressing the operation of the injection timing correction device 7, and reducing the amount of delay in fuel injection timing. It is configured as follows.

Note that 23 is a pressure relief hole for smooth vertical movement of the adjuster pin 12.

Next, the operation of the above embodiment will be explained. When the pressure is normal on a flat ground, the pressure detection member 11 of the injection amount control device 18 contracts, the adjuster pin 12 rises, and the correction lever 14 moves. Since the governor lever 17 rotates clockwise in the figure, the rotatable range of the governor lever 17 is large, so that the fuel injection amount is normally controlled according to the engine load.

On the other hand, a valve mechanism 22 connected to the correction lever 14
The valve body 20 is opened by the biasing force of the spring 21, and the return passage 7a of the injection timing correction device 7 is kept open. Therefore, when the engine is under low load, the injection timing control device 7 operates as usual to perform fuel injection. The timing is corrected to the delayed side, and emission performance etc. are improved.

On the other hand, if you move to a higher altitude and the atmospheric pressure decreases,
The pressure detecting member 11 of the injection amount control device 18 expands and the adjusting pin 12 descends, and is pushed by the tapered surface 13 of the adjusting pin 12 to move the correction lever 1.
4 rotates counterclockwise in the figure, and this correction lever 14
The rotation of the governor lever 17 restricts the movement of the governor lever 17, and the fuel injection amount is corrected to decrease.

At the same time, due to the rotation of the correction lever 14, the valve body 20 of the valve mechanism 22 is pushed in the valve closing direction against the biasing force of the spring 21, and the tapered tip of the valve body 20 opens the return passage. The passage area of a (outlet 19b of the valve storage chamber 19) decreases or becomes zero (blocked state), and as a result, even if the engine is in a low load state, the return passage 7
The fuel flow rate of a, that is, the amount of fuel discharged from the fuel chamber 2 through the return passage 7a is reduced, the drop in fuel pressure within the fuel chamber 2 is suppressed, and the amount of delay in fuel injection timing is reduced. , the fuel condition is stabilized and the output performance of the engine is ensured favorably.

Therefore, in the above embodiment, the injection amount control device 1
The control structure is simple because the pressure detection member 11 of No. 8 is used and the valve mechanism 22 is controlled to open and close by mechanically driving the pressure detection member 11 to suppress delays in fuel injection timing when atmospheric pressure decreases. Therefore, reliability can be improved.

Further, since only one pressure detection member 11 is required and a conventional solenoid valve is not required, costs can be reduced.

Figures 2 to 4 are the second to fourth figures of the present invention, respectively.
In the second embodiment shown in FIG. 2, the valve is shown in FIG. Connect the rear end of the valve body 20 of the mechanism 22' to the adjusting pin 1.
The valve body 20 is brought into contact with the tapered surface 13 of No. 2 so that the taper surface 13 directly pushes the valve body 20, and the inlet port 19a of the valve number storage chamber 19 is closed by the tapered tip of the valve body 20. Therefore, the same effects as those of the first embodiment can be achieved.

Further, in the third embodiment shown in FIG. 3, the valve mechanism 22"
The valve body 20' is fixedly suspended from the lower end surface of the adjusting pin 12 to be integrated with the adjusting pin 12,
The movement of the valve body 20' is made the same as the movement of the adjusting pin 12.

Therefore, in this embodiment, in addition to achieving the same effects as in the first embodiment, a separate valve body is not required, and the structure can be further simplified. This has the advantage that the durability of the valve body 20' can be improved.

Furthermore, in the fourth embodiment shown in FIG.
The midway portion of a is opened into a pin hole 24 into which the adjusting pin 12' is inserted, making the pin hole 24 a part of the return passage 7a, and the adjusting pin 1
A valve portion 25 is formed by cutting out the outer circumferential portion of the adjusting pin 2' over a predetermined axial length so that the diameter is smaller than that of the other portion.
5, by making the openings of the pin holes 24 of the return passage 7a communicate with each other or by blocking the communication,
Valve mechanism 22 that controls the fuel flow rate in the return passage 7a
' is being organized.

In FIG. 4, reference numeral 26 indicates a hole 27 formed at the periphery of the discharge side opening of the pin hole 24 opening of the return passage 7a, and which is gradually opened and closed by the valve portion 25.
is an O-ring that seals the adjusting pin 12'.

Therefore, in this embodiment, the adjusting pin 12
' itself has a valve function, it is possible to accurately control the fuel flow rate in the return passage 7a, and compared to the above-mentioned first to third embodiments, the high altitude correction and structure of the fuel injection timing can be achieved with higher accuracy. This has the advantage that it can also simplify the process.

As explained above, according to the present invention, there is provided an injection timing control device that controls the fuel injection timing based on the fuel pressure in the fuel chamber that changes depending on the engine speed, and a The movement of the governor lever is regulated by an injection timing correction device that discharges the fuel in the fuel chamber and corrects the fuel injection timing by the injection timing control device to the delayed side, and a pressure detection member that is displaced in response to fluctuations in atmospheric pressure. In a diesel engine fuel injection device comprising an injection amount control device that controls a maximum injection amount of fuel, the above-mentioned By using a valve mechanism that controls the fuel flow rate in the return passage of the injection timing correction device and reducing the amount of delay in fuel injection timing when atmospheric pressure drops, there is no need for a conventional solenoid valve. Since high altitude correction of fuel injection timing can be performed with a single pressure detection member, it is possible to provide a fuel injection device for a diesel engine with a high altitude correction function that has a simple structure, high reliability, and low cost. It is possible.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention; FIG. 1 is a vertical sectional view of a main part showing the first embodiment, and FIGS. 2 to 4 are longitudinal sectional views of main parts showing the second to fourth embodiments, respectively. It is a front view. 2...Fuel chamber, 7...Injection timing correction device, 7a...Fuel return passage, 11...
...Pressure detection member, 12.12'...Adjusting pin, 14...Correction lever, 17...
... Governor lever 18 ... Injection amount control device, 19 ... Valve storage chamber, 19a ... Inflow port, 19b ... Outflow port, 20 ,20'...
... Valve body, 21 ... Spring, 22.22
', 22". 22 "'... Valve mechanism, 25...
Benbe.

Claims (1)

[Scope of utility model registration request] An injection timing control device that controls fuel injection timing using fuel pressure in a fuel chamber that changes according to engine speed, and controls the injection timing by discharging fuel in the fuel chamber through a return passage when the engine is under low load. An injection timing correction device that corrects the fuel injection timing by the device to the delayed side, and an injection amount control device that controls the maximum injection amount of fuel by regulating the movement of a governor lever using a pressure detection member that is displaced according to fluctuations in atmospheric pressure. In the fuel injection device for a diesel engine, the fuel flow rate in the return passage of the injection timing correction device is controlled by a member connected to and directly driven by the pressure detection member of the injection amount control device. A fuel injection device for a diesel engine, characterized in that it uses a valve mechanism to reduce the amount of delay in fuel injection timing when atmospheric pressure decreases.