JPS5945821B2 - Diesel engine fuel injection system - 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 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 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, 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 determined by the movement of the governor mechanism driven by the rotation of the drive shaft 2.
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 It will be close to pressure, but spring 2
The plunger 21 is pushed back with an elastic force of 6.

Note that FIG. 1 shows a state in which the axis of the plunger 21 has been rotated by 90 degrees, and actually corresponds to 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
A rotated view is shown in the same figure.

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 (direction of arrow F 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 , 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.

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 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 3B, a cylinder 22 containing a plunger 21 is slidably housed inside a casing 31, and an oil chamber 32 is located at the right end of the cylinder 22, and an oil chamber 33 is also located at the left end of the cylinder 22. 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 normally open solenoid valve 36 as a valve device 36 is connected to the connection part of the passage 35.
A is interposed to close this 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.

Furthermore, in the end face high pressure chamber 23 and oil chamber 32 of the plunger 21,
A passage 40A, which is a second fuel passage, and a passage 40 are installed, respectively, and the two reverse passages 40A and 40 communicate with each other only when the cylinder 22 is shifted near the right end in the figure (Fig. 3B). reference).

That is, one passage 40A is provided through the bottom cloth of the cylinder 22, and the other passage 40 is provided through the bottom cloth of the cylinder 22.
An L-shaped groove is formed in the bottom cloth corner of 1, and only when the cylinder 22 is near the right end, both reverse paths 40A and 4
The high pressure chamber 23 and the oil chamber 32 communicate with each other through 0.

The solenoid valve 36A 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
By opening and closing A, the advance angle value is optimally feedback-controlled according to the engine operating state.

45 is an engine key, and 46 is a battery.

Note that 44 in FIGS. 3A and 3B is a long hole formed in the casing 31 to allow movement of the driving pin 20.
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 cylinder 22 is moved by the spring 37 to the position 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 F 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 Z 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 is 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. The passage 40 and 4OA are brought into communication, and the hydraulic pressure in the high pressure chamber 23 can be controlled by the solenoid valve 36A.

For example, if the injection timing determined by the control circuit 43 is later than the appropriate value, the solenoid valve 36A is closed and the passage 24'
Since the fuel pressure in the pump chamber 5 is led to the oil chamber 32 via the high pressure chamber 23 and the passages 40A and 40, the pressure in the oil chamber 32 increases and the cylinder 22 moves to the left, which causes the driving Pin 22 moves to the left.

When the communication between the passages 40A and 40 is cut off by the movement of the cylinder 22, the pressure in the high pressure chamber 23 rises to the same value as the pressure in the pump chamber 5, so the plunger 21 moves further to the left and adjusts the injection timing appropriately. to hasten.

Further, when retarding the injection timing, by opening the solenoid valve 36A, the injection timing can be quickly retarded by the opposite effect to that for advancing the injection timing.

Therefore, the injection timing can be maintained at an appropriate value depending on the engine operating state.

The control range is shown in Fig. 5, and the lower limit value C1 is the value of the valve device
The so-called minimum advance angle (2=0) state with 6 fully open [
3B], and C2 is the advance angle characteristic of the conventional plunger 21 plus an advance value of 11 at which the cylinder 22 moves to the left and cuts off communication between the passages 40A and 40 [Fig. 3C], and Driving pin 20 can be obtained at T1 at the time of starting, such as by obtaining a lead angle value [Fig. 3 A] that is advanced by a maximum of 1 compared to the conventional lead angle.
It is possible to have almost the entire range of movement of the robot as a control range.

Note that Lo is during the stroke of the driving pin 20.

As can be seen from the figure, since the solenoid valve 36A controls the oil pressure in a direction that lowers the oil pressure, the spring 26 is made weak and is set in the advance direction as much as possible, so that the control period can be widened.

FIGS. 6A and 6B show other embodiments.

In this embodiment, the second fuel passages 40 and 40A installed in the first embodiment shown in FIGS. aisle 40
' is provided with a one-way valve (one-way valve) 41 that allows flow only from the pump chamber 5 and an orifice 40/A.

Note that 41A is a spring that biases in the valve closing direction; 41B is a spring that biases the valve in the valve closing direction;
is an adjustment screw that adjusts the set load of the spring 41A.

To explain the operation, at the time of starting, the state shown in FIG. 6A, that is, the solenoid valve 36 is closed, so the oil in the oil chamber 32 is in a sealed state, and the advance angle state of l is maintained during cranking and starting.

When the engine is running, the solenoid valve 36A is opened and the fuel in the oil chamber 32 escapes through the passage 35, so the cylinder 22 is pushed all the way to the right side in the figure by the force F from the pump, as shown in Figure 6B. In this state, hydraulic pressure is applied to the high pressure chamber 23 of the plunger through the passage 24' in exactly the same way as in the conventional example, so that the injection timing characteristics are also the same as in the conventional example.

In this case, the fuel flows through passage 40' and orifice 40'A.

Although it continues to flow to the oil chamber 32 and the solenoid valve 36A1 passage 35,
Its flow rate is restricted by orifice 40'A.

On the other hand, for example, if the detected injection timing is later than the value determined by the control circuit 43, the control circuit 43 controls the solenoid valve 36A.
Close.

Then, the pressure in the oil chamber 32 increases due to the inflowing fuel, and this pressure continues to increase until it matches the pressure in the pump chamber 5.

As a result, the cylinder 22 can be moved to the left, so that the injection timing can be controlled within a maximum range of l.

Therefore, it is clear that the spring 26 is preferably selected so as to deviate in the advance direction from the required advance angle.

When the engine is stopped, it is in the state shown in Figure 6B, but since the force F from the pump 3 is gone, the cylinder 22 is pushed to the left in the figure by the force of the spring 37, as shown in Figure 6A. position, that is, the start angle state, and the operation stops.

Note that when the solenoid valve 36 is open, the passage 4 is removed from the pump chamber 5.
The orifice 40'A is installed because the fuel returns in the direction of the pump population 1 through 0' and 35, and this orifice 408 is connected to the inlet (control It may be provided in the passageway 35
It is clear that the fuel passing through may be returned to the fuel tank.

FIG. 7 is a graph showing when the second embodiment is under control, and shows that there are 1 times under control including the time of starting.

In the figure. is during the driving pin stroke (allowable advance angle fluctuation range)
, L is under control, C1 is the control lower limit value, and C2 is the control upper limit value.

In addition, when electronically controlling the injection timing, the injection timing including cranking is feedback-controlled to the optimum value, so l during control does not necessarily have to be the optimum starting advance angle for the idling position, but rather should be larger. It is more advantageous to use a grappling leg to delay the attack.

FIG. 8 shows yet another embodiment.

This one-way valve 41' is attached to the cylinder 22, and this one-way valve 41' consists of an orifice 4σ'A1 valve body 48 penetrating the cylinder 22, a spring 47, and a valve storage body 49. The function is essentially the same as that shown in the characteristic diagram of FIG.

That is, when the solenoid valve 36A closes during engine operation,
The oil chamber 32 communicates only with the high pressure chamber 23 via the one-way valve 41', so that the pressure in the oil chamber 32 increases until it becomes equal to the pressure in the high pressure chamber 23, thereby making it possible to move the cylinder 22 to the left. Therefore, the injection timing can be controlled within a maximum range of l.

However, for example, when the solenoid valve 36A is opened to retard the operating state shown in the figure, the pressure in the high pressure chamber 23 will drop at the same time as the oil chamber 32, and since the passage 24' is usually provided with an orifice 24A, the pressure will drop. Since the lowering speed becomes faster, the sensitivity to the movement of the solenoid valve 36A can be further improved.

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,
3A, B, and C are sectional views of the main parts of the present invention, FIG. 4 is an explanatory diagram showing the control system, FIG. 5 is a graph showing the advance angle characteristics of the present invention, and FIG. 6A, B is a cross-sectional view of the main parts showing other embodiments of the present invention, FIG. 7 is a graph showing the advance angle characteristics thereof, and FIG. 8 is a cross-sectional view of the main parts showing still another embodiment of the present invention. . 1... Pump inlet, 5... Pump chamber,
8...Eccentric disc, 20...
... Driving pin, 21 ... Plunger, 23 ... High pressure chamber, 24 ... Passage, 2
5...Low pressure chamber, 31...Casing,
32...Oil chamber, 33...Oil chamber, 35.
...First fuel passage, 36A... Normally open solenoid valve, 40°40'... Second fuel passage, 4
0A...Aisle, 40'A, 4σ'A...
... Orifice, 41, 41' ... One-way valve, 43 ... Control circuit, 48 ... Valve body.

Claims (1)

[Claims] 1. In a distribution fuel injection pump equipped with a feed pump and a plunger pump that pressurizes the discharged fuel,
A plunger interlocked with means for advancing the fuel injection timing is slidably housed in the cylinder, and the fuel discharged from the feed pump is applied to the other end of the plunger against a first spring interposed at one end of the plunger. A casing is provided to guide the cylinder while freely slidably housing the cylinder, and a second spring for biasing the cylinder in the advancing direction is interposed in one oil chamber formed between the cylinder and the casing. A first fuel passage is formed that communicates this oil chamber with the feed pump inlet side, and a valve device for opening and closing this fuel passage is provided, and the discharge fuel pressure of the feed pump is applied to the oil chamber when the cylinder is at a predetermined position. A diesel engine, comprising a control circuit that opens and closes the valve device to variably control the fuel injection timing according to the operating condition of the engine. Fuel injection device.