JPH037548Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a diesel engine with a swirl chamber that communicates with the main combustion chamber through a nozzle hole, and in particular reduces combustion noise and vibration during idling. Regarding measures to reduce

(Prior art) Generally, this type of diesel engine with a swirl chamber has one fuel injection nozzle that injects and supplies fuel into the swirl chamber, and the one fuel injection nozzle injects fuel along the swirl flow inside the swirl chamber. It uses a fuel injection structure that injects fuel in the following directions.
With this structure, the force of the vortex is weak when the engine is idling, especially when the outside temperature is low;
There was a problem in that the ignitability and combustibility of the fuel deteriorated due to the fact that the outer peripheral portion of the vortex was cooled by coming into contact with the low-temperature wall surface of the vortex chamber, and the absolute amount of fuel injection was small.

Therefore, in order to solve this problem, in addition to the usual main nozzle that injects fuel in the direction along the vortex flow inside the vortex chamber, as disclosed in, for example, Japanese Patent Application Laid-Open No. 54-74014, A sub-nozzle is provided that injects fuel toward the center of the swirl chamber rather than the nozzle.
Near the idling speed of the engine, fuel is injected from the sub-nozzle and diffused into the center of the vortex, which is kept at a relatively high temperature without contact with the wall surface, thereby improving ignition and combustibility during idling. A method has been proposed that can improve this.

By the way, in this proposal, the structure is such that the two fuel injection nozzles are simply switched depending on the operating state of the engine, so if fuel is injected from the sub nozzle at the normal injection timing, the injected fuel will be combustible. This results in a premixed state with increased combustion, which causes rapid combustion, resulting in a problem of increased combustion noise and vibration when the engine is idling.

(Purpose of the invention) This invention was made in view of the above points,
The purpose of this is to improve the ignitability and combustion of fuel when a diesel engine with a swirl chamber is idling, by appropriately controlling the injection timing of the fuel injected into the center of the swirl chamber when the engine is idling. The object of the present invention is to reduce combustion noise and vibration while improving performance.

(Structure of the invention) In order to achieve the above object, the structure of the invention includes a main nozzle that injects fuel in a direction along the vortex of the vortex chamber of a diesel engine with a vortex chamber, and a a sub-nozzle that injects fuel in the direction of the engine; and a sub-nozzle that injects fuel from the fuel injection pump to the main nozzle when the engine speed exceeds a predetermined rotation speed.
a nozzle switching device that selectively switches to supply fuel to each of the sub-nozzles at low engine speeds lower than a predetermined engine speed; and a nozzle switching device that selectively switches the fuel injection pump to supply fuel to each of the sub-nozzles when the engine speed is lower than a predetermined engine speed; It is a basic component of a main timing control device that controls the fuel injection timing to advance, and further has a predetermined amount of retardation than the maximum retard value of the main timing control device when fuel is supplied from the sub nozzle. It is equipped with a sub-timing control device that controls the timing to be delayed.

As a result, when the engine is idling, the sub nozzle injects fuel toward the center of the swirl chamber to promote ignition, and the fuel injection timing is delayed from normal timing to accelerate its rapid combustion. It is designed to suppress the

(Effect of the invention) Therefore, according to the invention, when a diesel engine with a swirl chamber is idling, the sub nozzle injects fuel toward the center of the swirl chamber, and the injection timing is changed from the normal timing. Since the speed is also slowed down, it is possible to effectively reduce combustion noise and vibration while improving fuel ignitability and combustibility during idling of a diesel engine with a swirl chamber.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a cylinder head of a diesel engine with a swirl chamber, in which a swirl chamber 3 is formed by an insert member 2, and the swirl chamber 3 is formed in the insert member 2. It communicates with the main combustion chamber (not shown) on the cylinder block side through the nozzle hole 4, and the compressed intake air (air) in the main combustion chamber is passed through the nozzle hole 4 and into the swirl chamber 3 during the compression stroke of the engine. It is designed to generate a swirl of intake air.

The cylinder head 1 also has the swirl chamber 3.
Two main and auxiliary nozzles 5 and 6 for injecting fuel into the interior of the vortex chamber 3 and a glow plug 7 that heats the interior of the vortex chamber 3 when starting the engine, etc. are attached. Consists of a throttle nozzle, etc., which is relatively small and has a large penetrating power.
The fuel is arranged so as to be injected in a direction along the vortex in the vortex chamber 3, that is, in a direction that hits the glow plug 7. On the other hand, the auxiliary nozzle 6 is comprised of a poppet nozzle or the like having a relatively large fuel spray angle and a weak penetrating force, and is arranged so as to inject the fuel toward the center of the swirl chamber 3 rather than the main nozzle 5.

Reference numeral 8 refers to the main and sub-nozzles 5, which correspond to the respective cylinders of the engine and which supply fuel to each cylinder of the engine in response to timing driving force.
6, the fuel injection pump 8 and main and sub nozzles 5,
In the middle of the fuel injection pipe 9 connecting to the fuel injection pipe 9, there is an electromagnetic switching valve 10 that operates to switch so that the fuel from the fuel injection pump 8 is supplied to the main nozzle 5 side when not energized, and to the auxiliary nozzle 6 side when energized. arranged,
The solenoid part of the electromagnetic switching valve 10 is connected to a battery 12 via an idle switch 11 that is turned ON when the engine speed is lower than a predetermined rotational speed (for example, 1000 rpm).
The idle switch 11 selectively switches the fuel pumped from the fuel injection pump 8 so that it is supplied to the main nozzle 5 when the engine speed is above a predetermined rotation speed, and to the sub nozzle 6 when the engine rotation speed is low than the predetermined rotation speed. A nozzle switching device 13 is configured.

Further, FIG. 2 shows the main part of the fuel injection timing control mechanism in the fuel injection pump 8, and 14
is a pump housing forming a pump chamber 15 for storing fuel; a roller holder 17 is supported in the pump chamber 15 of the pump housing 14 so as to be swingable around a drive shaft 16; A number of rollers 18, 18, . . . corresponding to the number of cylinders of the engine are rotatably supported, and the rollers 18, 18, . cam disc integrated into the (both not shown)
The plunger is rotationally driven by the drive shaft 16, and the cam disk rides on the rollers 18, 18, . . . to reciprocate, thereby causing the plunger to distribute fuel. It is designed to perform rotation for this purpose and reciprocation for pumping fuel. Further, the drive shaft 16 is attached to the pump housing 14.
A cylinder 19 is formed that extends in a direction perpendicular to the
A timer piston 22 is slidably fitted into the cylinder 19 to divide the cylinder 19 into a spring chamber 20 and a pressure chamber 21 , and the timer piston 22 is connected to the roller holder 1 via a pin 23 .
7. The above spring chamber 20
A spring 24 that urges the timer piston 22 toward the pressure chamber 21 is compressed, while the pressure chamber 21
communicates with the pump chamber 15 through a communication hole 22a formed in the timer piston 22, and when the engine speed increases during operation of the main nozzle 5, the fuel pressure in the pump chamber 15 and the pressure chamber increase accordingly. The pressure inside 21 increases and the timer piston 2
2 to the left in the figure against the biasing force of the spring 24, and rotate the roller holder 17 connected to the timer piston 22 clockwise in the figure to cause the roller holder 17 to move toward each roller 18. A main timing control device 25 is configured to advance the timing of fuel injection from the main nozzle 5 by advancing the timing at which each cam crest of the cam disk runs up.

Further, a support shaft 26 is rotatably supported on the pump housing 14 and is disposed perpendicularly to the drive shaft 16 so as to pass through the inside and outside of the pump housing 14, and a cam plate 27 is attached to the inner end of the support shaft 26. The cam plate 27 is integrally attached, and a cam top portion (eccentric end portion) of the cam plate 27 is provided with a protruding engaging portion 27a that engages with an engaging notch 17a formed in the roller holder 17. on the other hand,
A fulcrum portion of a retard lever 29 is rotatably attached to the outer end of the support shaft 26 and is rotatably biased by a return spring 28 made of a torsion spring. As shown in FIG. 1, a negative pressure actuator 31 is drivingly connected via a wire 30. The negative pressure chamber of the actuator 31 is communicated with a vacuum pump 33 via a negative pressure introduction passage 32, and a part of the negative pressure introduction passage 32 is opened by energization to supply the actuator 31 with negative pressure from the vacuum pump 33. A solenoid portion of the electromagnetic on-off valve 34 is connected to the idle switch 11. However,
Idle switch 11 turns ON and sub nozzle 6
When the sub nozzle 6 is activated, fuel is supplied from the
The actuator 3 is opened by the opening operation of the electromagnetic on-off valve 34.
1 to rotate the retard lever 29 and the supporting shaft 26 integrated therewith against the biasing force of the return spring 28, and the roller holder 17 is rotated by the cam plate 27 at the inner end of the supporting shaft 26. By rotating and holding the fuel injection timing by a predetermined angle in the counterclockwise direction (direction of retarding the fuel injection timing) in FIG. In other words, the retarded injection timing (for example, the fourth As shown by line B in the figure
A sub-timing control device 35 is configured to maintain the ATDC at 25 degrees.

Next, to explain the operation of the above embodiment,
After the engine is started with the fuel injection timing advanced to the TDC timing as shown in line A in Figure 4, the engine is idling at an idling speed (for example, 750 rpm) lower than the predetermined speed (1000 rpm). When there is, idle switch 11
is turned on and the electromagnetic switching valve 10 is operated, so that the fuel pumped from the fuel injection pump 8 is sent through the sub nozzle 6 to the approximate center of the swirl chamber 3, that is, to the swirl flow generated inside the swirl chamber 3. The fuel is injected toward the high-temperature center of the vortex that is not cooled by the wall surface of the vortex chamber 3, thereby improving the ignitability and combustibility of the fuel. At the same time, the negative pressure actuator 31 is activated by the opening operation of the electromagnetic on-off valve 34 accompanying the ON operation of the idle switch 11, and the retard lever 29 of the fuel injection pump 8, the support shaft 26, and the cam are activated. The plate 27 is rotated against the urging force of the return spring 28, and due to the rotation of the cam plate 27, the roller holder 17 is rotated and held in the retard side against the movement of the timer piston 22. As a result, the injection timing of the fuel injected into the swirl chamber 3 from the sub-nozzle 6 is retarded by a predetermined amount from the maximum retard value of the normal injection timing by the main timing control device 25, as shown by line B in FIG. be done.

In this case, the fuel injected from the sub-nozzle 6 is injected toward the high-temperature center of the swirl chamber 3 as described above, and ignition and combustion are performed extremely well. Even if the injection timing is delayed from the normal timing as in this example, the ignitability and combustibility of the fuel will not deteriorate, and conversely, it is possible to delay the injection timing without impairing the ignitability and combustibility of the fuel. As a result, rapid combustion due to delayed ignition of the fuel can be suppressed, and combustion noise and vibration can be reduced while improving the ignitability and combustibility of the fuel when the engine is idling.

On the other hand, when the engine speed rises above the predetermined speed, the idle switch 11 is activated.
When the electromagnetic switching valve 10 is turned off and the electromagnetic switching valve 10 stops operating, fuel from the fuel injection pump 8 is injected through the main nozzle 5 in a direction along the vortex flow inside the vortex chamber 3 . In addition, the actuator 31 does not operate due to the closing operation of the electromagnetic on-off valve 34, and the retard lever 29,
The support shaft 26 and the cam plate 27 are stopped and held by the biasing force of the return spring 28, and the roller holder 17 follows the movement of the timer piston 22 and rotates, thereby removing the vortex from the main nozzle 5. The injection timing of the fuel injected into the chamber 3 is corrected so that it advances accordingly as the engine speed increases, as shown by line C in Figure 4, improving the ignitability and combustibility of the fuel and increasing the engine output. This is expected to increase.

FIG. 3 shows a modification of the fuel injection timing control device (the same parts as in FIG. 25 is disposed inside the fuel injection pump 8'.

That is, in this modification, the fuel injection pump 8'
An auxiliary cylinder 36 extending in the same direction as the moving direction of the timer piston 22 is formed in the timer piston 22 , and is drivingly connected to the roller holder 17 through a pin 23 passing through the timer piston 22 . The auxiliary timer piston 37 is slidably fitted, and the auxiliary timer piston 37 causes the inside of the auxiliary cylinder 36 to be circularly connected to an auxiliary pressure chamber 38 on the pressure chamber 21 side and an auxiliary spring chamber 39 on the spring chamber 20 side. The image is formed.
An auxiliary spring 40 that urges the auxiliary timer piston 37 toward the auxiliary pressure chamber 38 is compressed into the auxiliary spring chamber 39 with the timer piston 22 as a spring receiving part. is set smaller than. On the other hand, the auxiliary pressure chamber 38 communicates with the pressure chamber 21 through the communication hole 22a of the timer piston 22, and also communicates with the pump chamber 5 in the pump housing 14 through the auxiliary communication hole 37a formed in the auxiliary timer piston 37. It is communicated. When the engine speed is lower than a predetermined speed (1000 rpm) and the engine speed increases within that range, the piston 22 does not move, but only the auxiliary timer piston 37 is affected by the biasing force of the auxiliary spring 40. By moving against the
As shown by line B' in FIG. 4, a sub-timing control device 35' is configured to control the injection timing of fuel injected from the sub-nozzle 6 to advance in proportion to the increase in engine speed. Incidentally, the vacuum pump 33, electromagnetic on-off valve 34, actuator 31, retard lever 29, support shaft 26, cam plate 27, etc. in the above embodiment are omitted.

Therefore, in this modification, the fuel injection pump 8' is equipped with two main and sub fuel injection timing control devices 2.
5 and 35' are provided side by side, which has the advantage that the device configuration can be simplified.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is an overall configuration diagram, FIG. 2 is a cross-sectional view of a main part of a fuel injection pump, and FIG. 3 is a cross-sectional view showing a modification of a fuel injection timing control device. FIG. 4 is a graph showing fuel injection timing characteristics. 1... Cylinder head, 3... Vortex chamber, 4...
Nozzle hole, 5...Main nozzle, 6...Subnozzle, 8,
8'...Fuel injection pump, 10...Solenoid switching valve,
11... Idle switch, 13... Nozzle switching device, 25... Main timing control device, 29...
Retard lever, 31... Actuator, 33...
Vacuum pump, 34...Solenoid on-off valve, 35,
35'... Sub-timing control device.

Claims (1)

[Scope of utility model registration request] In a diesel engine equipped with a swirl chamber that communicates with a main combustion chamber through a nozzle hole, a main nozzle injects fuel in a direction along the swirl of the swirl chamber, and a main nozzle that injects fuel toward the center of the swirl chamber from the main nozzle. and a sub-nozzle that injects the fuel, and selectively switches the fuel pumped from the fuel injection pump so that it is supplied to the main nozzle when the engine speed is above a predetermined rotation speed, and to the sub-nozzle when the engine rotation speed is lower than the predetermined rotation speed. a nozzle switching device; a main timing control device that advances the fuel injection timing of the fuel injection pump according to an increase in engine speed when the main nozzle is activated; 1. A swirl chamber type diesel engine, comprising: an auxiliary timing control device that retards the angle by a predetermined amount further than the angular value.