JPH1122596A - Start control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a start control device for a Diesel engine capable of obtaining the optimum fuel injection timing at the time of a start and in an operating region. SOLUTION: The plunger 4 of a fuel injection pump 1 is rotated by a control rack 6. A portion protruded higher than the reference height and a portion retracted lower than the reference height are formed in parallel in the peripheral direction of the plunger 4 on the peripheral face of the plunger 4 on the maximum effective stroke side. When the control rack 6 is received by an adjusting bolt 8, the peripheral portion of the plunger 4 acting on a feed hole 13 formed on the cylinder 3 of the fuel injection pump 1 is regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start control device for a diesel engine, and more particularly to a start control device capable of setting fuel injection timing in multiple stages.

[0002]

2. Description of the Related Art In a diesel engine, a plunger of a fuel injection pump is moved up and down in conjunction with an up and down movement of an engine piston, and the plunger opens and closes a feed hole of the fuel injection pump to inject fuel. I have. In this case, the fuel injection is started from a point where the engine piston reaches several degrees before the top dead center, and the cylinder internal pressure is set to be maximum at a position slightly beyond the piston top dead center, Normally, the injection timing is set so as to be an optimum injection timing in a rotation speed region of the operation operation.

[0003]

However, when the rotational speed in the operating region is set as a reference, the rotational speed is low in the region from start to idle rotation, and the so-called ignition delay from fuel injection to fuel ignition is short. In this case, combustion occurs for the first time before the optimum ignition position, and a sufficient output cannot be obtained. Also, since the engine maker sets the injection timing for the engine alone, the fuel injection timing may be such that the engine maker incorporates the engine and the working machine and the working machine acts as a load when the engine starts. However, there has been a problem that the engine speed becomes low and the engine speed becomes unstable.

[0004] It is an object of the present invention to provide a start control device for a diesel engine capable of obtaining an optimum fuel injection timing both at the time of start and in an operating range.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a fuel injection pump, in which a plunger protrudes upward from a reference position on an upper peripheral surface of the plunger on a maximum effective stroke side. And a part that retreats lower than the plunger is formed side by side in the circumferential direction of the plunger, and the peripheral position of the plunger that opens and closes the feed hole formed in the cylinder of the fuel injection pump is regulated by the receiving position of the control rack with the adjustment bolt. It is characterized by having been constituted so that.

[0006]

According to the present invention, the effective stroke constituted by the upper peripheral edge of the plunger of the fuel injection pump connected to the control rack and the upper edge of the control groove formed on the plunger peripheral surface is maximized. Side,
That is, a portion protruding above the reference height for setting the fuel injection timing in the normal operation state on the upper part of the plunger peripheral surface corresponding to the maximum fuel injection position or the fuel start increasing position, and a portion below the reference height. Since the retreating part is formed side by side in the plunger circumferential direction, if the part projecting above the reference height (projection part) acts on the feed hole, the fuel is added earlier than the reference fuel injection timing. When the pressure starts, it becomes a so-called advanced state, and the part that retreats below the reference height (retreat part) acts on the feed hole, the fuel pressurization starts later than the reference fuel injection timing, This is a so-called retarded state.

Since the control rack for controlling the effective stroke by rotating the plunger is received by the adjustment bolt on the fuel increasing side, the optimum fuel injection timing at the time of starting the engine can be easily set. Can be.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustrate embodiments of the present invention,
FIG. 1 is a partially cutaway perspective view of a fuel injection pump, FIG. 2 is a perspective view of a taken-out plunger of the fuel injection pump, and FIG. 3 is a partial developed view of a peripheral surface of the plunger. This fuel injection pump (1)
Is a pump casing (2) and this pump casing
(2) a pump cylinder (3) formed therein, a plunger (4) mounted in the pump cylinder (3) so as to be able to ascend and descend, and a control pinion ( 5) and this control pinion
A control rack (6) that meshes with (5) and a tappet (7) interlockingly connected to the lower end of the plunger (4);
Is provided.

The fuel injection pump (1) has a tappet (7) in contact with a fuel injection cam (not shown). The plunger (4) of the fuel injection pump (1) is raised and lowered by the operation of the fuel injection cam. Fuel is pumped into the engine cylinder of a diesel engine (not shown). Further, the fuel injection cam shaft fixing the fuel injection cam is operatively connected to the crankshaft of the engine via a reduction gear mechanism so that the fuel injection camshaft makes one rotation corresponding to two rotations of the crankshaft. It has become.

Control rack for fuel injection pump (1)
(6) is mounted on the pump casing (2) so as to be movable in and out, and is driven to move in and out by an engine governor mechanism (not shown). An end of the control rack (6) in the direction of movement toward the fuel increasing side (R) can be received by the adjustment bolt (8).

As shown in FIGS. 2 and 3, the plunger 4 of the fuel injection pump 1 has a control groove 9 formed on its peripheral surface in an inclined manner. The effective stroke of the fuel pressurization is formed between the upper peripheral edge of the plunger and the upper peripheral edge of the plunger (4).

The control groove (9) has an operating region (D) in which the fuel injection amount is increased or decreased during the operation of the engine, and a start operation region in which the amount of fuel is increased during the starting operation.
(I) and the starting operation region (I)
Is formed continuously with the maximum effective stroke portion in the operating region (D).

A portion corresponding to the starting operation area (I) at the upper edge on the peripheral surface of the plunger (4) is an operating operation area.
The height at the portion corresponding to (D), that is, the height that determines the fuel injection timing during the operation operation, is defined as the reference height, and the portion (10) having the same height as the reference height and the height above the reference height The projecting part (11) and the part (12) retreating beyond the reference height are formed, and the protruding part (11) and the retreating part (12) are continuously connected by an inclined straight line. ing.

As is well known, a fuel injection pump
In (1), the peripheral surface of the plunger (4) is the pump cylinder (3)
The fuel is pressurized by closing the feed hole (13) formed in the pump cylinder and pressure-fed to the engine cylinder, and the pressure in the pump cylinder is released by the control groove (9) communicating with the feed hole (13). However, if a part of the plunger peripheral surface protrudes from the reference height as described above, the fuel pressure feeding is stopped earlier than when the feed hole (13) is closed at the reference height, that is, the crank is stopped. In terms of the rotation angle, the fuel pumping starts in the advanced state. On the other hand, when a part of the plunger peripheral surface is retracted from the reference height, the timing is later than when the feed hole (13) is closed at the reference height, that is, the crank rotation angle is delayed. Then, the fuel pumping is started.

Then, the control rack (3) is adjusted with the adjusting bolt (8) so that the portion (10) having the same height as the reference height of the starting operation area (I) of the plunger (4) acts on the feed hole (13). In this case, the engine is started without changing the fuel injection timing. Further, the position of receiving the control rack (3) with the adjusting bolt (8) is adjusted to the projecting portion in the starting operation area (I) of the plunger (4).
When (11) is received while acting on the feed hole (13), fuel is injected at a timing earlier than the fuel injection timing in the operating state. On the other hand, the receiving position of the control rack (3) by the adjusting bolt (8) is received in a state where the retreating portion (12) of the plunger (4) in the starting operation area (I) acts on the feed hole (13). When the engine is started, the fuel is injected at a timing later than the fuel injection timing in the operating state. Especially,
When the protruding portion (11) and the retreating portion (12) are continuously inclined, the fuel injection timing at the time of retard can be finely adjusted by the receiving position of the adjusting bolt (8). .

FIGS. 4 and 5 show different embodiments of the plunger, which comprises a projecting part (11) and a retreating part.
The connection shape of (12) is a paragraph shape. As described above, when the projecting portion (11) and the retreating portion (12) are connected in a paragraph shape, the bolt can be easily selected by selecting a bolt from a plurality of adjusting bolts having different lengths set in advance. The fuel injection timing can be adjusted. In this case, if the upper edge of the control groove (9) corresponding to the protruding portion (11) is cut up by the same dimension as the protruding height of the protruding portion (11) as shown by a virtual line, the effective stroke at the protruding portion is increased. The length becomes the same as the effective stroke length in the start operation region immediately before the protrusion, the fuel amount in the start region becomes constant, and the generation of black smoke due to excessive fuel can be suppressed.

The retreating part (12) formed continuously with the protruding part (11) may be formed in a plurality of stages.

Normally, the fuel injection timing in a diesel engine is set on the basis of the number of revolutions used during operation,
The piston front dead center angle (reference angle) to be set is small for those used in a low rotation speed region, and the reference angle is set large for those used in a high rotation speed region.

On the other hand, the rotational speed during the start-up operation increases the rotational speed to almost the same rotational speed range regardless of the setting of the operating rotational speed. Whatever is the case. In addition, even if the engine is set to the same operating speed range, the rotational angular velocity is different between the engine that starts with the load connected to the output shaft and the engine that starts with no load. Therefore, the injection timing must be adjusted.

In this respect, in the present invention, a projecting portion (11) or a retreating portion (12) is formed on the upper part of the peripheral surface corresponding to the starting operation region of the plunger (4) of the fuel injection pump (1). Control rack for fuel injection pump (1) at (8)
By receiving the movement of (3) to the fuel increasing side, since the plunger peripheral surface portion acting on the feed hole (13) is positioned at the time of starting operation, the plunger is advanced or delayed with respect to the reference injection timing. The fuel is injected by squaring.

[0021]

According to the present invention, a portion of the plunger mounted on the fuel injection pump, which protrudes from a reference height for setting fuel injection timing in the operation operation region and retreats at an upper portion of a peripheral surface in a start operation region. And the adjustment rack receives the movement of the control rack that rotates the plunger to the fuel increase side. Regardless of the above, the optimal fuel injection timing for starting can be set.

Further, since three fuel injection timings at the time of starting can be set by one fuel injection pump, an arbitrary starting timing can be selected after the engine is mounted.

When the projecting portion and the retreating portion are connected by a continuous inclined surface, the receiving position of the control rack by the adjusting bolt is adjusted to adjust the inclined surface acting on the port hole of the fuel injection pump. The portion can be finely adjusted, and the fuel injection timing can be finely controlled.

On the other hand, when the projecting portion and the retreating portion are connected in a paragraph shape, the fuel can be easily prepared by selecting and using an appropriate adjusting bolt from a plurality of adjusting bolts having different lengths prepared in advance. The injection timing can be adjusted.

Further, if the upper edge of the control groove formed on the plunger of the fuel injection pump is cut off in accordance with the amount of protrusion and retreat on the upper peripheral surface of the plunger, the effective stroke length of the plunger is constant. , And the fuel injection amount can be kept constant, so that the generation of black smoke, which is likely to occur at the time of starting, can be suppressed.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a fuel injection pump.

FIG. 2 is a perspective view showing the removal of a plunger of the fuel injection pump.

FIG. 3 is a partially developed view of a peripheral surface of a plunger.

FIG. 4 is a perspective view of a plunger taken out according to another embodiment.

FIG. 5 is a partial development view of a plunger peripheral surface in another embodiment.

[Explanation of symbols]

1 ... fuel injection pump, 3 ... cylinder of fuel injection pump,
4 plunger of fuel injection pump, 6 control rack, 8 adjustment bolt, 9 control groove, 11
... projecting part, 12 ... retreat part, 13 ... feed hole, R ...
Fuel increase side.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuzo Umeda 64 Ishizukitamachi, Sakai City, Osaka Prefecture Inside Kubota Sakai Factory (72) Inventor Keita Naito 64 Ishizukitamachi, Sakai City, Osaka Prefecture 64 Inside Kubota Sakai Factory (72) Inventor Hidemasa Tsuji 64 Ishizukitacho, Sakai City, Osaka Prefecture Inside Kubota Sakai Works

Claims (5)

[Claims] A fuel injection pump (1) equipped in a fuel system of a diesel engine is configured to receive a moving amount of a control rack (6) to a fuel increasing side (R) of a fuel increasing side (R) with an adjusting bolt (8) and start. In a start control device for a diesel engine that regulates a fuel injection amount at the time, an upper peripheral surface of a plunger (4) of a fuel injection pump (1) linked to a control rack (6) on a maximum effective stroke side. The part protruding above the reference height that sets the fuel injection timing in the normal operation state (11)
And a portion (12) that retreats below the reference height are formed side by side in the circumferential direction of the plunger (4), and the fuel injection pump (1) is received by receiving the control rack (6) with the adjusting bolt (8). ) Feed hole formed in cylinder (3)
A starting control device for a diesel engine, characterized in that a peripheral portion of the plunger (4) that opens and closes (13) is positioned. 2. A portion (11) protruding continuously into the normal operation area.
And a part that retreats following the protruding part (11).
The start control device for a diesel engine according to claim 1, wherein (12) is formed. 3. The start control device for a diesel engine according to claim 2, wherein the projecting portion (11) and the retreating portion (12) are connected by an inclined surface. 4. The start control device for a diesel engine according to claim 2, wherein the projecting portion (11) and the retreating portion (12) are connected in a stepped manner. 5. The control groove (9) formed on the plunger (4), the upper peripheral surface of which is cut off in accordance with the amount of retraction of the upper peripheral surface of the plunger. A start control device for a diesel engine as described in the above item.