JPS5854250B2 - Diesel engine fuel injection timing control device - Google Patents

Description

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

In diesel engines, the fuel injection timing is variably controlled according to the engine speed, and the injection timing is advanced by a predetermined value even at startup to improve engine stability at startup.

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.

The supply pressure of the fuel discharged from the feed pump 3 is controlled by a pressure regulating valve 4, and then the fuel 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 7 is fixed to an eccentric disk 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 7 reciprocates while rotating, and as a result of this reciprocating movement, the fuel sucked from the suction port 12 is transferred from the distribution port 13 to the delivery valve 1.
4 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, 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 disk 8 rides on the roller 11, for example, in the opposite direction to the rotation direction of the disk 8 (when the roller ring 10 is rotated, the time when the face cam 9 rides on the roller 11 is injected). As the fuel injection timing 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 is connected to the suction side of the feed pump 3 (which communicates with the high pressure chamber 23). Although the pressure is almost negative, the elastic force of the spring 26 pushes back the plunger 21.

Note that FIG. 1 shows a state in which the axis of the plunger 21 is rotated by 90 degrees, and in reality, it coincides with the tangential direction of rotation of the roller ring 10 as shown in FIG.

Similarly, for convenience of explanation, the axis of the feed pump 3 is also 90
'The illustration shows the rotated version.

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 in FIG. The roller ring 10 is rotated in the opposite direction (in the direction of the arrow in the figure) 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, and the plunger 21 has an inclined end face.
A lever 29 that connects a cam 27 in contact with a rotating shaft 28
By turning O, the plunger 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 the operator often forgets to do the operation (this sometimes prevents the engine from starting smoothly).

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

In order to solve these problems, the present invention has a structure that allows the advance angle to be operated without being subjected to the load of the return spring of the plunger during startup, and the injection timing is advanced automatically using a small-capacity actuator. It provides equipment.

The present invention will be explained below based on some examples.

In the embodiment shown in FIGS. 3A and 3H, a cylinder 22 containing a plunger 21 is slidably housed inside a casing 31, with an oil chamber 32 at the right end of the cylinder 22 and an oil chamber 33 at the left end. form a section.

The oil chamber 32 communicates with the other oil chamber 33 and the suction side of the feed pump 3 through a passage 35, and a solenoid valve 36A is interposed as a valve device 36 at the connection part of the passage 35.
This passage 35 is closed for a predetermined period after startup to seal the oil chamber 32.

A spring 37 is interposed in the oil chamber 32 to move the cylinder 22 to the left, while an oil chamber 33 on the opposite side communicates with the low pressure chamber 25 of the cylinder 22 through a passage 38.

In addition, 39 is a seal ring, and 40 is a driving pin 2.
It is a long hole that allows movement of 0.

The casing 31 containing these is fixed to the pump housing so that a relationship similar to that shown in FIG. 2 is established.

The rest of the configuration is the same as that in FIG. 1, so illustration is omitted, and its operation will be explained next.

When the engine is stopped, the driving pin 20 is in a neutral state and no external force acts on it, and the fuel pressure drops equally, so the plunger 21 is moved by the spring 2 with respect to the cylinder 22.
6 and the casing 31 is moved by the spring 37 into the position shown in FIG. 3A, respectively.

When the engine is started in this state, the electromagnetic valve 36A is kept closed until the engine warms up as described later, so the hydraulic oil remains sealed in the oil chamber 32.

The driving pin 20 receives a reaction force to the right due to the rotation of the eccentric disc 8, but since the cylinder 22 cannot move to the right, an advanced angle corresponding to the distance l is obtained. The injection timing can be advanced appropriately.

Upon completion of warm-up (when the solenoid valve 36A opens, the cylinder 22
The left and right oil chambers 32 and 33 are connected to each other through a passage 35, and the pressure becomes the same, and at the same time, fuel can freely flow back and forth.

On the other hand, the cylinder 22 receives, via the plunger 21, the driving reaction force to the right in the figure that the driving pin 20 receives.
This was supported by the fuel sealed in the oil chamber 32, but when the electromagnetic valve 36A opens, the fuel can flow out, and the support is lost and it moves to the right in the figure.

In this case, the force of the spring 37 is applied to the driving pin 2.
Since the spring 37 is set to be small with respect to the rightward force of 0, the spring 37 is unilaterally bent, and the cylinder 22 is
It moves until it comes into contact with the stopper 41 of No. 1.

After this, the plunger 21 is displaced in proportion to the increase in fuel pressure in the hydraulic chamber 23 as the engine rotation increases, and the optimum injection advance angle can be obtained in accordance with the rotation speed, as in the conventional case.

Note that since the advance angle amount itself at the time of starting does not require a special driving force of the driving pin 20, it can be set larger than in the past, and an optimal advance angle state can be obtained.

FIG. 4 shows an example of a circuit for driving the solenoid valve 36A.

43 is an engine key switch, 44 is a starter switch, 45 is a self-holding relay, 46 is an oil pressure switch that detects the engine oil pressure and turns off when it exceeds a predetermined value (above a predetermined rotation), and 47 is a switch that turns off the engine after it has been warmed up. This is a water temperature switch that turns off when the cooling water temperature exceeds a predetermined value.

Therefore, since both switches 46 and 47 are on when starting the engine, by turning on the key switch 43 and the starter switch 44, the solenoid valve 36A is turned on.
is energized and closes.

Note that even if the starter switch 44 is turned off, the solenoid valve 36A is kept energized by the action of the self-holding relay 45.

This solenoid valve 36A includes an oil pressure switch 46 and a water temperature switch 4.
The valves are kept closed until both of the valves 7 and 7 are turned off.

Therefore, if the engine is started before it is sufficiently warmed up, the amount of advance of the injection timing will be in a state in which the amount of advance of the starting angle is added as shown in FIG. 5A.

Since the plunger 21 moves according to the fuel pressure while the oil chamber 32 is locked, the advance angle becomes relatively steep, and when the engine is running without sufficient warm-up (this is when the optimum injection advance angle can be obtained). .

In this regard, in the conventional example (FIG. 5B), only the initial value is the starting advance angle amount, and after that, the advance angle characteristics are normal.

FIG. 6 shows another embodiment of the drive circuit for the solenoid valve 36A, in which a microcomputer 50 is used to open and close the solenoid valve 36A in small increments in an on/off manner based on the duty. (controls the average opening degree), the injection timing is advanced by a predetermined value at startup, and is gradually returned to match the warm-up condition.
Further improves combustion stability.

The microcomputer 50 has atmospheric temperature, fuel temperature,
Input engine oil temperature, engine water temperature, engine rotation, exhaust temperature, time after startup, etc., and check the settings for optimal control.

Next, in the embodiment shown in FIG. 7, a thermostat valve 36B is provided in place of the solenoid valve 36A, and includes a thermostat 53 that expands upon sensing a rise in fuel temperature, and a poppet valve 54 that is pushed up and opened when this expansion occurs. It consists of

When the temperature is low, the poppet valve 54 is closed by a spring 55, and the oil chamber 32 is opened after warming up.

FIG. 8 shows a bimetal valve 36C in which a bimetal 56 is attached in place of the thermostat 53, producing similar effects.

As explained above, according to the present invention, the amount of injection advance required at the time of starting can be obtained with a relatively simple structure and a small actuator, and in particular, it is easy to advance the starting angle automatically. .

The amount of advance can be set arbitrarily large according to the request, and when driving during warm-up, the relative Q can be adjusted according to the request.
This injection timing can be advanced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional device, Fig. 2 is a partial sectional explanatory view showing the relationship between the roller ring and plunger in Fig. 1, and Fig. 3 is a sectional view of a conventional device.
Figures A and B are cross-sectional views showing the operating state of the first embodiment of the present invention, Figure 4 is a solenoid valve drive circuit diagram, Figures 5 A and B are advance angle characteristics diagrams of the present invention and the conventional one, and Figures FIG. 6 is a block diagram of the other side of the electromagnetic valve drive circuit, and FIGS. 7 and 8 are schematic configuration diagrams showing respective embodiments of the present invention. 8...Eccentric disc, 10...
... Roller ring, 20 ... Driving pin, 21 ... Plunger, 22 ... Shiffrinder, 23 ... High pressure chamber, 25 ...・
Low pressure chamber, 26... Spring, 31...
・Casing, 32, 33...Oil chamber, 35...
...Passage, 36...Valve device, 36A...
...Solenoid valve, 36B...Thermostatic valve, 36C...Bimetal valve, 37...
···spring.

Claims (1)

[Scope of Claims] 1. A plunger interlocked with a means for advancing fuel injection timing, a cylinder housing this plunger that responds to fuel pressure that is approximately proportional to engine speed, and a cylinder that accommodates this plunger in the axial direction of the plunger. It consists of a casing that is freely slidable, a valve device that opens and closes an oil chamber of the casing that is partitioned on the end face of the cylinder, and a spring means that biases the cylinder in the advance direction (Q). A fuel injection timing control device for a diesel engine, comprising means for relatively moving the fuel injection timing. 2. The fuel injection timing control device for a diesel engine according to claim 1, wherein the valve device is a solenoid valve that is kept closed during warm-up. 3. The fuel injection timing control device for a diesel engine according to claim 1, wherein the valve device is a thermostatic valve that closes when the engine temperature is low. 4. The fuel injection timing control device for a diesel engine according to claim 1, wherein the valve device is a bimetallic valve that closes when the engine temperature is low.