JPS59695B2 - Injection timing adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection timing adjustment 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 at startup. ing.

For this reason, conventional fuel injection pumps are constructed as shown in FIGS. 1 and 2.

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

After the supply pressure of the fuel discharged from the feed pump 3 is controlled by a pressure regulating valve 4, it is supplied to a pump chamber 5 inside the pump housing.

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

The plunger l is fixed to an eccentric disc 8 and is driven by the drive shaft 2 via a 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 γ reciprocates while rotating, and as a result of this reciprocating movement, the fuel also sucked into the suction port 12 is forced into 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 1.
The spill port 15 is determined by the position of the spill ring 16 that covers the spill port 5.
When it 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 a link lever 19 by the movement of a 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 timer piston 21 via.

The fuel pressure of the pump chamber 5 is introduced to the end face high pressure chamber 23 of the timer piston 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. Although the pressure is close to negative, the timer piston 21 is pushed back by the elastic force of the timer spring 26.

In addition, in Fig. 1, the axis of the timer piston 21 is 9115)
It is shown in a rotated state, and actually corresponds to the tangential direction of rotation of the roller ring 100 as shown in FIG.

Similarly, for convenience of explanation, the axis of the feed pump 3 is also 98.
A rotated version 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 timer piston 21 is pushed to the left in FIG. The roller ring 10 is rotated in the opposite direction to the rotation (in the direction of the arrow in the figure), and acts to gradually advance the injection timing.

On the other hand, in order to improve the combustion characteristics at the time of starting, there is a manual advance device, in which the cam 2T, which is in contact with the timer piston 21 whose end face is slanted, is rotated by turning a lever 29 connected to a rotating shaft 28. However, the timer piston 21 is forcibly moved to the left to advance the injection timing by a predetermined crank angle.

However, in the conventional device, the lever 29 is manually operated like this.
Since the engine is configured to drive the engine, the required starting operation is complicated, and smooth engine starting is sometimes hindered due to forgetting to operate the engine.

In particular, a spring 26 that counteracts and balances the fuel pressure during normal operation is constantly acting on the timer piston 21, and the spring force is quite strong. There is a problem that the force is small and a large actuator or the like is required.

Further, since the advance angle device during operation is of the fuel hydraulic piston type, there are also problems such as the balance between the hydraulic pressure and the spring 26 being unstable, resulting in large variations in the advance angle.

The present invention was made by focusing on these conventional problems, and has a structure that allows advance angle operation without being subjected to the load of the return spring of the timer piston, as well as reading the advance angle value to ensure that the advance angle is always appropriate. The objective is to solve the above problems by adding an electronic control device that performs feedback control on the angle value.

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

Figures 3 to 5 show an embodiment of the invention.

In FIG. 3, a timer piston 21a is attached to the tip of a driving pin 20 that is integrated with a roller ring (not shown).
are connected to each other, and this timer piston 21a is connected to a cylinder 22.
It is slidably housed in a.

Inside the cylinder 22a, there is a B on both sides of the timer piston 21a.
A pressure chamber 31 and an A pressure chamber 30 are formed, and both pressure chambers 30
, 31, the timer piston 21a is displaced left and right.

A timer piston 2 is provided in these A and B pressure chambers 30 and 31.
The pump chamber 5 passes through the oil passages 37 and 38 provided in 1a.
of pressure oil (fuel) is introduced.

The pressure oil introduced into both pressure chambers 3L30 can escape to the outside of the cylinder 32a through the B relief hole 32 and the A relief hole 33, which are provided with orifices 32a and 33a, respectively.

Further, a spring 34 is installed inside the A pressure chamber 30,
The spring 34 is set to have its natural length when the timer piston 21a is separated from the right wall surface of the cylinder 22a by a starting advance angle value t under no load.

On the other hand, the guide hole 3 provided at the bottom of the timer piston 21a
9 is provided with a racked plunger 40 that slides in the piston movement direction independently of the timer piston 21a.

This plunger 40 is connected to the timer piston 21a.
By displacing left and right relative to the oil passage 3
The effective opening area of the B outlet 35 of the oil passage 38 and the A outlet 36 of the oil passage 38 are increased and decreased reciprocally, thus forming a kind of hydraulic servo valve.

Further, a needle valve 41 is provided at the right end of the plunger 40, so that it closes the A relief hole 33 when the plunger 40 moves to the rightmost end.

Incidentally, the sliding movement of the plunger 40 is realized by a rack 42 provided below the center and a pinion 43 meshing with the rack 42.

That is, as is clear from the I-I cross-sectional view in FIG.
A pinion 43 is provided on a motor shaft 45 of a drive motor 44 attached to the outside of the cylinder 22a, and the plunger 40 is slid back and forth by forward and reverse rotation.

Note that the guide hole 39 of the timer piston 21a has a notched window 42a at the rank 420 portion, and the pinion 43 is disposed in this notched window 42a.

By communicating the cutout window 42a with the pump port 1 through the escape hole 48, leakage of pressure oil is prevented.

In addition, 46 is an oil seal, and the motor flange 41
is pressed to an appropriate pressure.

As shown in FIG. 5, a control device 50 that rotates the motor 44 in forward and reverse directions calculates and processes various detection signals such as injection timing, atmospheric temperature, and engine speed, and outputs appropriate command values to the motor 44.
4 and performs feedback control.

Note that 51 is a power supply, and 52 is an input switch.

Next, the action will be explained.

A control device 50 calculates the optimum injection timing according to the operating condition based on detection signals such as injection timing and atmospheric temperature from various sensors, and controls the drive motor 44 to obtain this optimum timing.
Give a command signal for forward and reverse rotation.

For example, when advancing the injection timing, the pinion 43
is turned counterclockwise to send a command signal to the motor 44 to move the plunger 40 to the left in FIG.

Then, the plunger 40 reduces the opening area of the B outlet 35 and reduces the amount of pressurized fuel flowing into the B pressure chamber 31.
The outlet 36 is widened to increase the amount of fuel flowing into the A pressure chamber 30.

Therefore, the pressure in the B pressure chamber 31 decreases, and conversely, the pressure in the A pressure chamber 30 increases, causing the timer piston 21a to move to the left to an advanced position of the fuel injection timing.

From 1fflK of the timer piston 21a, the timer piston 21a stops when the opening areas of the A and B outlets 36 and 35 become equal again (at a position where the left and right pressures are balanced).

When retarding the fuel injection timing, by rotating the pinion 43 in the opposite direction (clockwise) to the above, the height of the fuel pressure with respect to both pressure chambers 30, 31 is reversed, and the timer piston 21a is retarded. It moves to.

In addition, in these controls, via the plunger 40,
The reaction force acting on the pinion 43 is caused by the diameter of the plunger 40.
\Because it is small, it is extremely small and therefore has a small capacity motor 4
4 will be enough.

The starting advance angle is performed as follows.

When the engine is stopped, the timer piston 21a spring 34
It is energized by the starting advance angle value t.

The elastic force of the spring 340 may be relatively weak since no pressure drop occurs in the B pressure chamber 31 when the engine is stopped.

When the start switch 52 is turned on, the F/
> rotates the pinion 43 via the motor 44 and slides the plunger 40 to the rightmost end.

Then, the needle valve 41 closes the A relief hole 33, and the
At the same time as stopping the outflow of the fuel, the plunger 40 also closes the person outlet 36 and seals the fuel in the A pressure chamber 30.

Therefore, even if a strong force is applied to the driving pin 20, the timer piston 21a is fixed at a position where a predetermined starting advance angle value is maintained, and the optimum starting advance angle is automatically achieved.

FIG. 6 shows another embodiment in which a plunger 40 is installed above the timer piston 21a.

In this way, when air gets mixed into the A pressure chamber 30, the air can be discharged from the A relief hole 33, and more stable hydraulic control can be expected.

FIG. 1 shows yet another embodiment in which the A pressure chamber 30 is provided with an air vent communication passage 48.

Although the A relief hole 33 is closed by the needle valve 41, gas and air accumulated in the A pressure chamber 30 can be discharged from the communication path 48.

When the plunger 40 is located at the rightmost position, the needle valve 41 closes the A relief hole 33 and the communication passage 48, thereby sealing the A pressure chamber 30.

As described above, in the present invention, oil passages connected to the pressure chambers at both ends of the timer piston are provided inside the piston, and these oil passages are opened and closed via a plunger that moves in the sliding direction of the piston, so that the injection timing is always controlled. Feedback control can be performed accurately and responsively to the optimum advance angle value, and the starting advance angle can also be automated.

At the same time, the structure is simple and compact, and can be produced at low cost.

[Brief explanation of the drawing]

FIG. 1 is an overall sectional view of a conventional distribution type fuel injection pump, and FIG. 2 is a sectional view of a timer piston portion. FIG. 3 is a sectional view of the main part of the present invention, FIG. 4 is a sectional view taken along the line I-I, FIG. 5 is a control circuit diagram of the present invention, and FIGS. 6 and 1 are of other embodiments. It is a sectional view of the main part. 20... Driving pin, 21a... Timer piston, 22a... Cylinder, 30... A pressure chamber, 3
1...B pressure chamber, 32...B relief hole, 33...A
Relief hole, 34... Spring, 35... B exit, 36...
・A outlet, 37° 38...Oil passage, 40...Plunger, 41...Needle valve, 42...Rack, 43...
Pinion, 44...motor, 50...control device.

Claims (1)

[Claims] 1. In an injection timing adjustment device for a distribution type fuel injection pump that advances or retards the injection timing according to the movement of a timer piston,
Two pressure chambers having relief holes are formed at both ends of the timer piston, and the timer piston is provided with two oil passages that communicate with the pump chamber and these two pressure chambers, and a plunger is provided to open and close the oil passages. An injection timing adjustment device characterized in that the plunger is actuated by a signal from a control device depending on the operating state.