JPS60192840A - Fuel injection timing controller for distribution fuel injection pump - Google Patents

Abstract

PURPOSE:To improve the accuracy of injection timing control by communicating the pressure chamber not communicatable with the fuel pressure feed chamber partitioned through a plunger in a timing chamber communicating with the fuel pressure feed chamber to the low pressure chamber through a solenoid valve. CONSTITUTION:A timing plunger 19 is provided slidably in a timing chamber 18 communicated with a fuel pressure feed chamber 31. The pressure chamber 20 at the side not communicatable with the fuel pressure feed chamber 31 partitioned through said plunger 19 is communicated through a solenoid valve 6 and a supply port 11 to the low pressure chamber 8. The amount of fuel in the pressure chamber 20 is controlled by the solenoid valve 6 to vary the stroke of plunger 19 thus to control the fuel injection timing. Consequently, the injection timing can be controlled highly accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a distribution type fuel injection pump, and particularly to a fuel injection timing control device that enables electrical control and has a simplified structure.

[Technical background of the invention]

Generally, a fuel injection pump is used in a diesel engine because it is necessary to supply fuel at high pressure to its combustion chamber. There are two types of fuel injection pumps of this type: morning type and distribution type, but distribution type pumps are often used in small high-speed diesel engines because they are small, lightweight, and have fewer parts.

Among conventional distribution type fuel injection pumps, the so-called Lusus type has a rotor inserted into the hydraulic head, and a cam ring with a pair of pressure-feeding plungers attached to the outer circumference of the rotor. By reciprocating the rotor, a pumping action is performed, and the fuel supplied to the fuel pumping chamber in the center of the rotor is pumped to the cylinder side. In this case, the rotor is provided with distribution ports in the radial direction, and correspondingly, the same number of discharge boats as the number of engine cylinders are formed at intervals in the circumferential direction on the inner peripheral surface of the head, and as the rotor rotates, the injection ports are formed. Fuel is distributed to each cylinder of the engine according to the order.

Incidentally, in this type of fuel injection pump, it is necessary to accurately control the fuel injection amount and injection timing, and in recent years there has been a tendency to electronically control these, and various proposals have been made. In the case where the injection amount is controlled, a solenoid valve fills fuel into a fuel feeding chamber in which fuel is pressurized to high pressure by a pressure feeding plunger, and the injection amount per injection is controlled by the opening time of the solenoid valve. It was to be decided. On the other hand, in the case where the injection timing is controlled, the injection timing is controlled by operating the piston using the hydraulic pressure adjusted by the solenoid valve and the balance between the springs, adjusting the rotation amount of the cam ring, and adjusting the operation timing of the plunger. It was supposed to be under control.

[Problems with background technology]

Since the above-described injection timing control m+ mechanism uses a hydraulic servo mechanism, this hydraulic servo mechanism is complicated, and there are problems in that the operation timing and injection timing of the hydraulic servo mechanism are likely to deviate during the period of use.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and has a simplified structure by enabling electrical control of fuel injection timing.
It is an object of the present invention to provide a fuel injection timing control device for a distribution type fuel injection pump that can provide highly accurate operation.

[Summary of the invention]

In order to achieve the above object, the distribution type fuel injection pump according to the present invention communicates with the timing chamber a fuel pumping chamber that receives compression as the pumping plunger moves forward, or a high pressure chamber that has the same pressure as the fuel pumping chamber. Then, this timing chamber is divided into two by a slidable timing plunger, and among the two divided chambers by this timing plunger, the pressure chamber on the side that does not communicate with the above-mentioned fuel pumping chamber or high pressure chamber is connected via a solenoid valve. The timing plunger is moved by opening the pressure chamber with a relief valve when the pressure-feeding plunger compresses the fuel, and the injection timing is adjusted by making the amount of movement invalid for fuel injection. In other words, the opening time of the electromagnetic valve is controlled to adjust the movement amount of the timing plunger to control the actual fuel pumping start timing.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4.

As shown, the distribution injection pump has a casing 1
a sleeve 2 mounted within the sleeve 2;
It has a hydraulic head 3 mounted inside.

The hydraulic head 3 has a rotor 4 inserted therein which is rotated by an engine (not shown).

The sleeve 2 has a mounting hole through which the outer surface of the hydraulic head 3 faces. In this installation, a pair of holes are provided along the axial direction of the rotor 4, and a first solenoid valve 5 and a second solenoid valve 6 are respectively installed in these holes.

Due to the mounting of the electromagnetic valves 5, 6, the mounting defined by the outer surface of the head 3 forms valve chambers 7, 8 in the holes. Further, the head 3 is provided with a fuel supply path 9, which is fed from a feed pump (not shown), at a central position between the two valve chambers 7 and 8, and this supply path 9 is connected to the two valve chambers 7,8. It is opened. Therefore, the fuel passes through the supply path 9,
1st. It is introduced into the second valve chambers 7 and 8. The valve chambers 7 and 8 have a first valve formed in the hydraulic head 3. The second supply boat 10.11 is opened and each boat 10.11
The openings can be opened and closed by valve bodies 12 and 13 of electromagnetic valves 7 and 8. 1st. The second solenoid valves 7, 8 are normally closed valves, and the valve bodies 12, 13 are solenoid coils 14.1.
By energizing the valve 5, the springs 16 and 17 are actuated to communicate the valve chambers 7 and 8 with the supply boats 10 and 11, thereby introducing fuel into the supply boats 10 and 11.

The first supply boat 10 is oriented toward the central axis of the rotor 4 and opens at the inner wall surface of the head 2 through which the rotor 4 is inserted.

The second supply boat 11 communicates with a timing chamber 18 provided in the head 3. A timing plunger 19 is fitted into the timing chamber 18 so as to be slidable in the axial direction.
8 is divided into two into a pressure chamber 20 and a pressure chamber 21. The second supply boat 11 is in communication with the pressure chamber 20. One end of this pressure chamber 20 further communicates with a drain hole 48 via a drain passage 23 via a relief valve 22 . Further, the pressure chamber 21 divided by the timing plunger 19 communicates with an annular groove 24 formed in the inner wall surface of the head 2 through which the rotor 4 is inserted.

A first inlet boat 25 corresponding to the first supply boat 10 is formed in the rotor 4 . As shown in FIG. 3, this inlet boat 25 has a plurality of channels radially bored at equal intervals in the circumferential direction of the outer circumferential surface of the rotor 4, and the number of channels is equal to the number of engine cylinders (in the example embodiment). It is compatible with 6 cylinders). Therefore, as the rotor 4 rotates, the supply boat 10 of the head 3 and the inlet boat 25 of the rotor 4 are intermittently brought into communication. Further, a second inlet boat 26 is formed in the rotor 4 so as to face the annular groove 24 connected to the pressure chamber 21 . The second inlet boat 26 is always in communication with the annular groove 24, that is, the pressure chamber 21, no matter what position the rotor 4 is rotated to. A free piston 30 is provided on the rotation center axis of the rotor 4 so as to be slidable in the axial direction, and the interior of the rotor 4 is divided into two into a fuel pumping chamber 31 and a high pressure chamber 32 by the free piston 30. There is. The end opening of the fuel pumping chamber 31 is sealed by a sealing screw 33. Further, the high pressure chamber 32 is communicated with a pressure increase chamber 34 through a pressure increase passage 34a.

On the other hand, the rotor 4 is inserted into the hydraulic head 3 as described above, but the end portion on the side forming the pressure increasing passage 34a protrudes from the side surface of the head 3.
The outer surface of the protrusion is covered by a cam ring 35. This cam ring 35 is attached to the casing 1 adjacent to the sleeve 2, and has cam ridges 36 formed in a wave shape on its inner peripheral surface as shown in FIG. The cam ridges 36 are formed in a number equal to the number of engine cylinders at equal intervals along the circumferential direction. Also, the rotor 4 facing the cam ring 35
A pair of pressure-feeding plungers 37 are housed in through holes bored in the diametrical direction of the rotor. A cam roller 3 is connected to the tip of the pressure-feeding plunger 37 via a roller shoe 38.
9 is attached so that the cam row 539 can slide into contact with the cam ridge 36 of the cam ring 35. The pressure plunger 37 is pushed into the rotor 4 at the same time as the cam roller 39 comes into contact with the cam crest 36 as the roller 4 rotates. The pressure boosting chamber 34 in the rotor 4 defined by the pressure feeding plunger 37 is connected to the pressure boosting passage 3.
4a, and the pumping action of a pressure-feeding plunger 37 operates within the pressure-increasing passage 34a. Boost passage 3
Pressure based on the reciprocating movement of the pressure-feeding plunger 37 acts on the above-mentioned high pressure chamber 32 communicating with the piston 3, and the free piston 30 reciprocates due to this pressure. Therefore, the pumping action of the free piston 30 acts on the fuel pumping chamber 31.

Further, a distribution boat 40 communicating with the fuel pumping chamber 31 is bored in the radial direction at the other end of the rotor 4 . As shown in FIG. 4, the distribution boat 40 has an opening on the inner peripheral surface of the hydraulic head 3, and corresponding to this opening, there is a hole on the inner peripheral surface of the head 3 that can communicate with the distribution boat 40. The discharge boat 41 is opened. The discharge boats 41 are formed by radially perforating the head 3, and are formed at equal angles in the same number as the number of engine cylinders.

Each discharge boat 41 and distribution boat 40 communicate with each other when the first supply boat 10 and the first inlet boat 25 are in a disconnected state. They are formed at positions shifted by 1/2 of the circular angle. The discharge boat 41 is communicated with each combustion chamber of the engine (not shown) via a discharge hole 42 and a delivery valve, respectively.

Furthermore, the rotor 4 has a first. 2nd inlet boat 25
．． A radial spill boat 45 is formed between 26 and 26.

This spill boat 45 is placed in a phased relationship with the inlet boats 25, 26 by an angle of 1/2 of the angle between the boats. Each boat of this spill boat 45 is open to the inner circumferential surface of the hydraulic head 3, and can be connected to a communication path 46 formed in the hydraulic head 3. This communication passage 46 opens into the high pressure chamber 32 when the free piston 30 is moved to the right in FIG. 1, and is further connected to a low pressure passage 47 formed in the sleeve 2. The low pressure passage 47 communicates with a drain hole 48 opened in the casing 1 .

50 is a control circuit such as a microcomputer, which provides a valve opening signal and a valve closing signal to the first and second electromagnetic valves 7.8. This IJil1 circuit 50 receives detection signals from each sensor Na-Nh that detects the operating status of the diesel engine. For example, each sensor
, engine speed Nb, engine oil! Nc, engine cooling water mNd.

Acceleration distance Ne, atmospheric temperature Nf, fuel temperature NQ.

When signals are given to the control circuit 50 from these sensors Na-Nh, the control circuit 50 calculates the fuel injection amount and injection timing, and controls each electromagnetic valve 7, 8. Gives valve open and close signals.

The distributed fuel injection pump configured as described above operates as follows.

When the rotor 4 rotates and the first inlet boat 25 is connected to the first supply boat 10, the other distribution boats 40 and Yasbill boat 45 are cut off. At this time, when a valve opening signal is given to the first solenoid valve 5 from the control circuit 50, the fuel that has been sent to the valve chamber 7 through the supply path 9 passes through the first supply boat 10 and the first inlet boat 25. The free piston 30 is supplied to the fuel pumping chamber 31, so that the free piston 30 moves in a direction that reduces the volume of the high pressure chamber 32 due to the pressure. The high pressure chamber 32 and each flow path connected thereto are filled with fuel in advance, so the fuel pushed out from the high pressure chamber 32 pushes open the pressure-feeding plunger 37 through the pressure increase passage 34a.

Further, at this time, when a valve opening signal is applied to the second electromagnetic valve 6 from the burial circuit 50, the fuel that has been fed into the valve chamber 8 from the supply path 9 flows into the pressure feeding chamber 20 from the second supply boat 11.

This fuel operates the timing plunger 19 and increases the pressure in the high pressure chamber 32, thereby pushing the pressure feeding plunger 37 further open.

Next, the first. When a valve closing signal is applied to the second solenoid valve 5.6,
The valve bodies 12 and 13 are the first. The second supply boats io and 1i are opened and the supply of fuel to the fuel pumping chamber 31 and the pressure chamber 20 is completed.

Then, when the rotor 4 rotates, the fuel pumping chamber 31 is moved to the first
It is cut off from the supply boat 10. At this time, distribution boat 4
0 and the discharge boat 41 are brought into electrical continuity.

When such boat switching is performed, the cam roller 3 is attached to the cam ridge 36 of the cam ring 35 at the end of the rotor 4.
9 rides on the pump and presses the pressure-feeding plunger 37 inward, so that the fuel pressure in the booster 34 increases and the fuel in the flow path from the booster passage 34a to the high-pressure chamber 32 becomes high pressure. This fuel pressure is transmitted from the annular groove 24 to the pressure guiding chamber 21 and pushes the timing plunger 19 to the left in the figure. For this reason, the pressure chamber 20
When the pressure becomes higher than the biasing force of the spring of the relief valve 22, the relief valve 22 is pushed open, and the fuel in the pressure chamber 20 is released through the drain passage 23. The fuel in the pressure chamber 20 is released from the relief valve 22.
Timing plunger 19 until all are released through
moves to the left, and at this time the fuel pressure in the high pressure chamber 32 does not increase.

When the timing plunger 19 stops moving, the high pressure chamber 3
2 fuel pressure begins to rise.

When the fuel pressure in the high pressure chamber 32 increases, the free piston 30
to press the fuel in the fuel pumping chamber 31. Therefore, the fuel in the fuel pumping chamber 31 flows out from the discharge boat 41 via the distribution boat 40 and is injected into the combustion chamber of the engine via a delivery valve (not shown) or the like.

Then, when the free piston 30 is moved by the high pressure fuel in the high pressure chamber 32 and the spill boat 45 is opened at the end face of the free piston 30, the high pressure chamber 32 is communicated with the communication path 46 via the spill boat 45.

Therefore, the high pressure fuel in the high pressure chamber 32 is transferred to the spill boat 4.
5 and escapes to the low pressure side. Therefore, the pressure of the fuel from the fuel pumping chamber 31 to the distribution boat 40 becomes low, and the injection ends.

By repeating the above operations, the fuel feeding chamber 31 sucks in the fuel supplied from the first electromagnetic valve 5, compresses and discharges it, and distributes and injects the fuel.

Here, since the injection amount injected into the engine combustion chamber is determined by the amount of fuel supplied from the first electromagnetic valve 5 to the fuel pumping chamber 31, it can be controlled by the opening time of the first electromagnetic valve 5.

Further, the injection time is adjusted from the second solenoid valve 6 to the pressure chamber 20.
Timing plunger 19 due to m of fuel supplied to
is determined by the amount by which the timing plunger 19 moves backward, that is, by the amount by which it is moved to the left. Therefore, it is determined by the opening time of the second solenoid valve 6. Can be controlled by valve opening time.

Therefore, according to this embodiment, the injection timing can be controlled by a solenoid valve, and there is no need for a complicated mechanism such as the conventional one in which the cam ring is rotated by hydraulic pressure to adjust the injection timing, so the structure is simple and compact. can. moreover,
Since the injection amount and injection timing can be controlled for each injection, accurate control can be performed even when operating at a very high speed.

Another embodiment of the present invention will be described based on FIG.

In FIG. 5, fuel is sucked from the inlet 1°.1 of the pump body through a feed pump 103 driven by a drive shaft 102 in synchronization with the engine. The fuel discharged from the feed pump 103 is supplied to a pump chamber 105 inside the pump housing after the supply pressure is controlled by a pressure regulating valve 104. The fuel in the pump chamber 105 lubricates the operating parts and at the same time supplies the suction boat 10.
6 and is sent to the high pressure plunger pump 107.

A pressure-feeding plunger 108 of this pump 107 is fixed to an eccentric disk 109, and a joint 110
It is driven by the drive shaft 102 via the drive shaft 102. The eccentric disk 109 has the same number of seven-eighth cams 111 as the number of engine cylinders (not shown), and reciprocates by a predetermined cam lift while rotating over the same number of rollers 113 as the face cams 111 disposed on the roller ring 112.

Therefore, the pressure-feeding plunger 108 reciprocates while rotating, and along with this reciprocating movement, the suction boat 10
The fuel sucked from the distribution boat 115 is forced to be sent to an injection nozzle (not shown) through a delivery valve (not shown). The amount of fuel to be injected is determined by the position of the spill ring 117 with respect to the IFI of the spill boat 116 formed on the pressure-feeding plunger 108. For example, if the spill ring 117 moves to the left and the pressure-feeding plunger 108 moves to the right, the spill boat 116 communicates with the low-pressure pump chamber 105 earlier, the high-pressure fuel is released earlier (the injection end time is earlier), and the fuel injection The amount decreases. The position of the spill ring 117 is controlled via a link lever 119 by the movement of a governor mechanism 118 driven by the rotation of the drive shaft 102, and the amount of fuel injection is increased or decreased in accordance with the engine speed.

Note that FIG. 5 shows the axis of the pressure-feeding plunger 108 rotated by 90 degrees, and for convenience of explanation, the axis of the feed pump 103 is also shown rotated by 90 degrees.

One end of the timing plunger 121 installed in the piston head 120 faces a pressure chamber 123 communicated with the fuel pumping chamber 122 and also faces a pressure chamber 124 . Pressure chamber 124 is connected to pump chamber 105 via relief valve 125. Further, the pressure chamber 124 is communicated with the pump chamber 105 via an introduction hole 126 and a communication hole 127. The introduction hole 126 and the communication hole 127 are connected to the solenoid valve 128.
communication is cut off. injection timing,
The operating state is detected by various sensors Na-Nh that detect the engine rotation speed and engine oil temperature, and based on the detected values, the control circuit 129 calculates the fuel injection timing,
This causes the solenoid valve 128 to open and close. Solenoid valve 12
8 is a solenoid coil 13 in response to the supplied control signal.
0 is excited, the valve body 131 is activated, thereby communicating and blocking the introduction hole 126 and the communication hole 127.

Next, the operation of this embodiment will be explained.

The control signal is processed by the control circuit 129 according to the operating state of the engine, and the supplied control signal is sent to the pressure-feeding plunger 108.
During the suction stroke, the solenoid valve 128 is opened for a certain period of time. The pressure chamber 124 is connected to the communication hole 12 from the pump chamber 105.
7 and the fuel that has flowed in through the introduction hole 126, the timing plunger 121 moves by a predetermined amount to the right in the figure.

When the pressure-feeding plunger 108 enters the pressure-feeding stroke, the solenoid valve 128 closes at this time. When the fuel in the fuel pumping chamber 132 is pressurized, the timing plunger 121 discharges the fuel in the pressure chamber 124 to the pump chamber 105 via the relief valve 125. Therefore, the timing plunger 121 moves to the left, so that the fuel in the fuel pumping chamber 132 is discharged into the pressure guiding chamber 123. The plunger 108 has a pre-stroke by the amount of movement of the timing plunger 121, and the pressure feeding is delayed, that is, the injection timing is delayed.

By the way, there are various variations in the injection timing control device,
If the actual fuel injection timing deviates from the optimal injection timing due to sudden fluctuation factors, the sensor Na detects the injection timing, so the solenoid valve 128 is controlled via the control circuit 129.
The injection timing is corrected by increasing or decreasing the valve opening time, and feedback control is performed to always maintain the optimum injection timing.

Even in such an embodiment, appropriate injection timing can be obtained with a small and simple structure.

〔Effect of the invention〕

As described above, according to the present invention, the timing chamber is communicated with the fuel pumping chamber or the high pressure chamber having the same pressure, and the timing plunger is slidably provided in the timing chamber.
The amount of movement of the timing plunger is controlled by a solenoid valve, and since injection of fuel from the fuel pumping chamber is started after the timing plunger finishes its movement, the timing of fuel injection is controlled by the solenoid valve. I can do it. This provides the advantage that the fuel injection timing can be controlled with high precision and the structure is simple.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, FIG. 1 is a sectional view, and FIGS. 2 to 4 are II in FIG. 1, respectively.
-I line, ■-■ line, 15 J: Hi IV -IV i!
17) Cross-sectional view FIG. 5 is a cross-sectional view showing another embodiment of the present invention. 35.36.38.39,111.113...Cam mechanism, 37,108...Forcing plunger, 31°132
...Fuel pumping chamber, 10.106...Suction port, 4
1.115...Discharge boat, 18...Timing chamber, 19.121...Timing plunger, 20,1
24...Pressure chamber, 6.128...Solenoid valve, 22.1
2-5...Relief valve. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] The rotational motion transmitted from the drive source is converted into a reciprocating motion of the pressure-feeding plunger by a cam mechanism, and when the pressure-feeding plunger retreats, fuel is introduced from the suction boat into the fuel pressure-feeding chamber, and when the pressure-feeding plunger moves forward, fuel is introduced into the fuel pressure-feeding chamber. In a distribution type fuel injection pump that pressurizes fuel and distributes it from a discharge port, a timing chamber is communicated with the fuel feeding chamber or a high pressure chamber having the same pressure as the fuel feeding chamber, and a timing plunger is slidably provided in the timing chamber. , the pressure chamber on the side not communicating with the fuel pressure chamber or the high pressure chamber divided by the timing plunger is il
The pressure chamber is connected to a low pressure chamber through a valve, and this pressure chamber is provided with a relief valve that opens when the pressure reaches a predetermined level, and the stroke of the timing plunger is controlled by controlling the fuel amount in the pressure chamber with the solenoid valve. A fuel injection timing control device for a distribution type fuel injection pump, characterized in that the fuel injection timing is controlled by changing the fuel injection timing.