JPS5945820B2 - 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 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, 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 γ is fixed to the eccentric link disc 8 and is driven by the drive shaft 2 via the joint 2A.

The eccentric link 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 fuel injection fee is supplied through 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 relink 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 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 has a negative Although the state is close to pressure, the spring 26
The plunger 21 is pushed back by the elastic force.

Note that FIG. 1 shows a state in which the axis of the plunger 21 is rotated by 90 degrees, and actually 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 image is shown rotated by °.

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 fuel 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 , 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 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 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.

Furthermore, since the advance angle device during operation is of the fuel-hydraulic piston type, the balance between the hydraulic pressure and the spring 26 is 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 plunger, and also reads the advance angle value to always maintain the appropriate value. The purpose of this invention is to solve the above problems by adding an electronic control device that performs feedback control on the advance angle value.

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 is connected to the other oil chamber 3 by a first fuel passage 35.
3 and the suction side of the feed pump 3, but a first valve device 36c is connected to the connection part of the passage 35! : A normally open solenoid valve 36A is interposed to close the passage 35 and seal the oil chamber 32 for a predetermined period of time after startup.

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.

First fuel passage 35 and end face high pressure chamber 23 of plunger 21
are communicated with each other by a second fuel passage 40, and a normally closed solenoid valve 4 is connected to this passage 40 as a second valve device 41.
1A is inserted, and the passage 40 is opened as necessary to open the high pressure chamber 2.
3 flows out to the suction side of the pump 3 via a passage 35.

The second fuel passage 40 includes a normal passage hole 40A formed in the casing 31 and a slit-shaped passage hole 40B formed in the cylinder 22.

Therefore, the slit-shaped passage hole 40B allows the cylinder 22
Regardless of the positional movement of the solenoid valve 41A, the communication state is always maintained upstream of the solenoid valve 41A.

Further, in the plunger 21, a communication passage 42 is formed diagonally inside the plunger 21 so that the passage 40 and the high pressure chamber 23 (pump chamber 5) communicate with each other even when the plunger 21 is positioned all the way to the right in the figure.

In the figure, 44 is a long hole formed in the casing 31 to allow movement of the driving pin 20.

The slit-shaped passage hole 40B is shown in FIG. 5A.

As shown in B, it is formed on the casing 31 side, and the cylinder 2
The through hole 40A may be formed on the second side, or the communicating path 42 may be formed as an open groove 42' on the circumferential surface of the plunger 21 (or cylinder 22).

and the first and second solenoid valves 36A.

41A is controlled to open and close by a control circuit 43 as shown in FIG.

The control circuit 43 receives signals from an injection timing detection device (not shown) that detects atmospheric temperature, engine water temperature, engine rotation, etc., and injection timing (advance value) from movement of the needle valve of the injection nozzle, fuel pressure in the injection passage, etc. is input, and based on these, the above-mentioned solenoid valve 36
A and 41A are opened and closed to optimally feedback control the advance angle value according to the engine operating state.

Note that 45 is an engine key and 46 is a battery.

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 to the right in the figure, and the cylinder 22 is moved by the spring 3.
7 to the left in the figure to the positions shown in FIG. 3A, respectively.

When the engine is started in this state, the solenoid valve 36A is kept closed by a signal from the control circuit 43 until it warms up as described later, so the hydraulic oil remains sealed in the oil chamber 32. becomes.

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.

When the warm-up state progresses and reaches a certain stage, the solenoid valve 36A opens its opening in small increments in response to a signal from the control circuit 43, and the injection timing, which was advanced by a predetermined value at the time of startup, is returned little by little to match the warm-up state. Finally, the solenoid valve 36A becomes open (no current applied).

This state is shown in FIG. 3B, where the cylinder 22 moves to the right in the figure against the spring 37 due to the force acting on the driving pin 20, comes into contact with the stopper part of the oil chamber 32, and is fixed to the casing 31. It is in a state of being

After this, as the engine speed increases, the plunger 21 is displaced in proportion to the increase in fuel pressure in the high pressure chamber 23, similar to the conventional example described above, and the injection advance is automatically obtained, but the injection timing is The control circuit 43 determines this using the method described above, and if it is ahead of the appropriate value, the solenoid valve 41A is opened, the pressure in the high pressure chamber 23 is lowered, and the plunger 21 is moved to the right, thereby changing the injection timing to engine operation. It can be delayed to an appropriate value depending on the situation.

Therefore, it is clear that the advance angle characteristic when the solenoid valve 41A is in the closed state should be designed in the advance direction rather than the appropriate value as a whole.

FIG. 6 is a flowchart showing the operational sequence of the control action described above.

In other words, if the injection timing calculated based on input of engine water temperature, intake air temperature, engine rotation, injection timing, etc. is later than the pre-stored injection timing reference value, for example, if the water temperature is higher than the specified value. If so, close the second solenoid valve 41, and if it is less than the specified value, close the first solenoid valve 3.
6 is closed until the air warms up to advance the injection timing.

On the other hand, if the water temperature is ahead of the reference value, for example, if the water temperature is below a specified value, the first solenoid valve 36 is opened for t seconds, and if it is above the specified value, the first solenoid valve 36 is opened at this time. If not, open it, and if it opens, the second solenoid valve 41
The injection timing is delayed by, for example, opening the engine for t seconds.

Such operations are continuously repeated from the time the engine starts to the time the engine stops.

Note that if the first fuel passage 35 is formed as an open groove on the outer peripheral surface of the cylinder 22 or the inner peripheral surface of the casing 31, and a solenoid valve 41A for opening and closing this opening groove is provided, processing of the passage 35, etc. is easy. becomes.

As explained above, according to the present invention, it is possible to automatically obtain the injection advance amount required at startup with a simple structure, and
This has the effect that the injection timing during operation can be variably controlled to an appropriate value depending on the engine operating state via the control circuit.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the conventional device, Figure 2 is a sectional view of its main parts,
FIGS. 3A and 3B are sectional views of the main parts of each of the present invention, FIG. 4 is an explanatory diagram showing the control system, and FIGS. 6 are flowcharts showing the injection timing control procedure of the present invention. 20...Driving pin, 21...
Plunger, 22...Cylinder, 31...
...Casing, 1...Pump inlet, 32...
... Oil chamber, 35 ... First fuel passage, 36
...First valve device, 23... High pressure chamber,
40... Second fuel passage, 41... Second valve device, 43... Control circuit.

Claims (1)

[Scope of Claims] 1. A plunger that responds to fuel pressure in conjunction with means for advancing fuel injection timing, a cylinder that slidably houses this plunger, and a casing that slidably houses this cylinder. a first fuel passage that communicates the fuel supply passage upstream of the feed pump with the oil chamber between the cylinder and the casing; a first valve device that opens and closes the fuel passage; and a first valve device that opens and closes the fuel passage; A second fuel passage that communicates with the first fuel passage, a second valve device that opens and closes the fuel passage, and an injection timing detection device that detects the injection timing are provided in the oil chamber between the eleventh cylinder, respectively, A fuel injection timing control device for a diesel engine, characterized in that the first and second valve devices are controlled to open and close according to engine operating conditions to variably control the fuel injection timing. 2. The diesel engine according to claim 1, wherein the first and second valve devices are controlled to open and close based on engine operating conditions such as engine cooling water temperature, intake air temperature, and engine rotation speed via a microcomputer. fuel injection timing control device. □3 The second fuel passage is formed by a slit in either the cylinder or the casing, and a through hole communicating with the slit in the other.
A fuel injection timing control device for a diesel engine according to item 1 or 2.