JPS5945822B2 - Injection timing control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection timing control device for a fuel injection pump such as a diesel engine.

In diesel engines, the fuel injection timing is variably controlled according to the engine speed, but the injection timing is also advanced by a predetermined value at startup to improve startability and engine stability during startup. I have to.

For this reason, a conventional fuel injection pump is constructed as shown in FIG.

Fuel is sucked from an inlet 1 of the pump body by a feed pump 3 driven by a drive shaft 2.

The fuel discharged from the feed pump 3 is supplied to a pump chamber 5 inside the pump housing after its supply pressure is controlled by an output regulating valve 4.

The fuel in the pump chamber 5 lubricates the operating parts and is simultaneously sent to the high pressure plunger pump 6.

The plunger γ is fixed to the eccentric disc 8 and is driven by the drive shaft 2 via the joint 2A.

The eccentric disk 8 has the same number of face cams 9 as the number of engine cylinders, and reciprocates by a predetermined cam lift while rotating over rollers 11 disposed on a roller ring 10.

Therefore, the plunger 7 reciprocates while rotating, and as a result of this reciprocating movement, the fuel sucked from the suction port 12 is forced to be sent from the distribution port 13 through the delivery valve 14 to an injection nozzle (not shown).

The amount of fuel injected is determined by the spill port 1 formed in the plunger 7.
The spill port 15 is determined by the position of the spill ring 16 that covers the spill port 5.
When the pump opens, the high pressure fuel is released into the inside of the pump housing 5 and the pumping is completed.

The position of the spill ring 16 is controlled via the link lever 19 by the movement of the governor mechanism 18 driven by the rotation of the drive shaft 2, and the amount of fuel injection is increased or decreased in accordance with the engine speed.

The fuel injection timing is controlled by rotating the roller ring 10.

Since fuel is injected when the face cam 9 of the eccentric disc 8 rides on the roller 11, for example, if the roller ring 10 is rotated in the opposite direction to the rotational direction of the disc 8, the time when the face cam 9 rides on the roller 11 is determined. Since this becomes earlier, the fuel injection timing relative to the engine crank angle becomes earlier.

For this purpose, the roller ring 10 is connected to the driving pin 20.
It is connected to the plunger 21 via.

The fuel pressure of the pump chamber 5 is introduced to the end face high pressure chamber 23 of the plunger 21 sliding in the cylinder 22 through a passage 24, and the low pressure chamber 25 on the opposite side communicates with the suction side of the feed pump 3 and is negative. Although the state is close to pressure, the elasticity of the spring 26 pushes back the plunger 21.

Note that FIG. 1 shows a state in which the axis of the plunger 21 has been rotated by 900 degrees, which actually corresponds to the tangential direction of rotation of the roller ring 10.

Similarly, for convenience of explanation, the axis of the feed pump 3 is also 90
A rotated view is shown in the same drawing.

Since the fuel pressure in the pump chamber 5 increases in proportion to the rotation speed of the feed pump 3, the plunger 21 is pushed to the left as the engine rotation speed increases, thereby causing the plunger 21 to move in the opposite direction to the rotation of the eccentric disc 8. The roller ring 10 is rotated to gradually advance the injection timing.

The spring 26 urges the plunger 21 within a cylinder 22, which is slidably housed within a casing 27, and is urged by a spring 28 to the left in the drawing, that is, in the advance angle direction.

An orifice 32 is provided in a first fuel passage 31 that communicates the right high pressure side oil chamber (A chamber) 29 formed between the cylinder 22 and the casing 21 and the left injection pump inlet side 30,
A normally open first solenoid valve 33 for starting that opens and closes the orifice 32 is attached to the casing 2γ.

Further, a port 35 is provided which communicates the first fuel passage 31 downstream of the orifice 32 and the end face high pressure chamber (C chamber) 23 via the slit 34 of the cylinder 22.
A second solenoid valve 36 for normal operation advance that opens and closes is attached to the casing 27.

At the time of startup, as shown in FIG. 2A, the spring 28 in the A chamber 29 causes the casing 27 and plunger 21 to
is biased in the advance angle direction (to the left in the drawing), and since the first electromagnetic valve 33 extends across the orifice 32, it is maintained at a predetermined advance angle position l at the time of starting.

After starting, as shown in FIG. 2B, the first solenoid valve 33 opens the orifice 32, and the force F applied to the driving pin 20 causes the casing 27 and plunger 21 to move to the retard position (normal operating position).

During subsequent operation, the injection timing is advanced by opening and closing the second solenoid valve 36.

The opening and closing of the second solenoid valve 36 and the first solenoid valve 33 are controlled by a control circuit (microcomputer) 3γ as shown in FIG.

The control circuit 37 includes injection timing, atmospheric temperature, engine water temperature,
Detection signals S to S7 such as engine speed are input,
Based on these signals, the solenoid valves 33 and 36 are opened and closed to optimally feedback control the advance angle value according to the engine state.

For example, the control circuit 37 determines the injection timing, and if it is later than the appropriate value, closes the second solenoid valve 36, so the pressure in the end high pressure chamber (C chamber) 23 rises through the passage 24, and the plunger 21 moves in the advance direction ( move to the left of the drawing).

Further, when retarding the injection timing, by opening the electromagnetic valve 36, the injection timing can be quickly retarded by the opposite effect to that in the case of advance.

In this way, the pressure within the injection pump, which is generated in proportion to the engine rotation, is adjusted to a predetermined pressure depending on the engine operating state, thereby controlling the injection timing to an optimum value.

Note that 38 in FIG. 3 is an engine key switch, and 39 is a battery.

However, in such a conventional injection timing advance device, injection timing control during startup and injection timing control during normal operation are performed by separate solenoid valves 33 and 36, so that the solenoid valves Two pieces are required, resulting in high cost.

Another problem was that the configuration became complicated.

This invention was made by focusing on such conventional problems, and a second fuel passage is provided that communicates the A chamber between the casing and the cylinder with the pump chamber, and a single solenoid valve is used to control startup and normal operation. By controlling both injection timing,
The purpose is to solve the above problems.

The present invention will be explained below based on the drawings.

FIGS. 4A and 4B are diagrams showing an embodiment of the present invention.

First, to explain the configuration, the slit 34, the port 35 and the second solenoid valve 36 are removed from the conventional injection timing advance device described in FIGS. A second fuel passage 40 is provided which communicates the inside of the pump chamber 5 with the A chamber (right side oil chamber) 29 between the pump chambers.

This passage 40 is formed between the inner periphery of the casing 27 and the outer periphery of the cylinder 22, and is an elongated orifice-shaped groove with a sufficiently small passage area.

The orifice 32A, which is opened and closed by the solenoid valve 33A, is for draining fuel from the A chamber 29, but at the same time
It is provided in the upper part of the A chamber 29 in order to improve air escape from the chamber 29.

FIG. 5 shows a control circuit 37A of the solenoid valve 33A, and shows the conventional control circuit diagram shown in FIG. 3 with the second solenoid valve 36 removed.
A controls the injection timing both at startup and during normal operation.

Note that the fuel pressure in the pump chamber 5 is constantly applied to the A chamber 29 through the second fuel passage 40 .

Next, the effect will be explained.

When the engine is stopped, the solenoid valve 33A is open, the driving pin 20 is in a neutral state, and the reaction force F of the driving force of the plunger 7 does not act, and the fuel pressure equally decreases to zero, so that the cylinder 22, the plunger 21 is moved to the far right by the spring 26 on the left side of the figure, and the cylinder 22 is moved to the far left by the spring 28 on the right side of the figure, as shown in FIG. 4A.
It is moved as shown in .

When the engine is started in this state, the solenoid valve 33A is held open by a signal from the control circuit 37A until warm-up progresses as described later, so the hydraulic oil is almost sealed in the A chamber 29. It will remain as it is.

Driving pin 20 is eccentric disc 78
However, the second fuel passage 40 receives a reaction force F to the right due to the rotation of
Since the effective cross-sectional area of the cylinder 22 is sufficiently small that the cylinder 22 cannot move to the right, an advanced state corresponding to the turning distance l is obtained, and in this way, the injection timing at startup can be appropriately advanced.

When the warm-up state progresses and reaches a certain stage, the solenoid valve 33A opens its opening in small increments in response to a signal from the control circuit 37A, and the injection timing, which was advanced by a predetermined value at startup, is returned little by little to match the warm-up state. , finally the solenoid valve 33A is open (
(no power).

This state is shown in FIG. 4B, where the cylinder 22 is moved to the right in the figure by the force acting on the driving pin 20 (via the pressure of the oil chamber 23) against the spring 28, and the A chamber 29 is moved to the right in the figure.
A normal operating state is established in which the hydraulic pressure in the A chamber 29 can be controlled by the solenoid valve 33A.

At this time, since the fuel pressure in the pump chamber 5 is constantly acting on the high pressure side oil chamber (C chamber) 23 through the passage 24, the plunger 2
1 moves to the left in the figure against the spring 26 to adjust the position of the driving pin 20.

During normal operation, the control circuit (computer) 37A inputs detection signals such as engine speed, load, injection timing, etc., and opens and closes the solenoid valve 33A- in small steps to achieve the optimal injection timing stored in advance. Control.

For example, the control circuit 37A determines the injection timing, and if it is later than the appropriate value, the solenoid valve 37A is closed, so that the pressure in the A chamber 29 rises through the second fuel passage 40 and the cylinder 22
moves to the left in the figure, that is, in the advance angle direction, and as a result, the plunger 21 moves in the advance angle direction.

Further, when retarding the injection timing, by opening the solenoid valve 33A, the injection timing can be quickly retarded by the opposite effect to that in the case of advance.

That is, when the solenoid valve 33A is opened, the fuel in the A chamber 2'9 passes through the first fuel passage 31 and is discharged from the cylinder 22.
moves to the right in the figure, that is, in the retard direction, and the plunger 21
moves in the retard direction together with the cylinder 22.

By opening and closing the solenoid valve 33A in this way by the control circuit 37A, the injection timing can be automatically maintained at any appropriate value depending on the engine operating state.

Although the second fuel passage 40 is formed in a groove shape on the inner periphery of the casing 27 in the embodiment, it has been experimentally shown that this can be replaced by making the gap between the inner periphery of the casing 27 and the outer periphery of the cylinder 22 somewhat larger. It has been confirmed.

As explained above, according to the present invention, a fuel passage with a small cross-sectional area is provided between the casing and the cylinder to constantly communicate the pump chamber and the A chamber, and a single solenoid valve is used for starting and normal operation. Since both injection timings are controlled, the number of solenoid valves can be reduced from two to one, which not only simplifies the structure but also reduces costs.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the conventional device, Fig. 2 A and B are cross-sectional views of its main parts, Fig. 3 is a circuit diagram showing its control system, and Fig. 4 A and B are cross-sectional views of the main parts of each of the present invention. 5 are circuit diagrams showing the control system of the present invention. 20...Driving pin, 21...
Plunger, 22...Cylinder, 23...
...Hyperpressure chamber, 24...Aisle, 25...
Low pressure chamber, 26... Spring, 27... Casing, 28... Spring, 29... A chamber (oil chamber), 31...・First fuel passage, 32A...
... Orifice, 33A ... Solenoid valve, 37
A...Control circuit, 40...Second fuel passage.

Claims (1)

[Claims] 1. A plunger that responds to fuel pressure in conjunction with means for advancing the fuel injection timing, a cylinder that slidably houses the plunger, a casing that slidably houses the cylinder, and a cylinder that slideably houses the plunger. A spring that biases the plunger toward the retard side and a spring that biases the cylinder toward the advance side within the casing are provided, and the pressure side oil chamber between the cylinder and the casing and the injection pump inlet side are provided. A first fuel passage that communicates with the fuel passage, a valve device that opens and closes the fuel passage, and a second fuel passage that constantly communicates the oil chamber and the pump chamber are provided, and the valve device opens and closes according to the operating state of the engine. An injection timing control device characterized in that the fuel injection timing is variably controlled.