JPS63223351A - Control method for fuel injection pump of internal combustion engine - Google Patents

Abstract

PURPOSE:To eliminate biting-in of foreign matters easily by sensing the pressure in a pressure chamber, furnishing an opening/closing valve which is to adjust the fuel press feed amount through control of the relief amount of the chamber when the sensed pressure does not attain a specific value within a certain timing, and by increasing the relief amount from this opening/closing valve. CONSTITUTION:A distribution pump 1 pressurizes the fuel inhaled in a pressure chamber 4 with reciprocative and rotary motions of a plunger 5 and supplies it to an injection valve 16 through a discharge passage 11 and a distribution passage 13. Fuel press feed amount is controlled by open/close controlling a spill valve 2 (opening/closing valve) arranged on a path which leads the chamber 4 to the low pressure side. Here the output signal from a gap sensor 60 to sense the position of plunger 5 is fed to a control circuit together with the generated voltage at a piezo actuator 52 of an injection ratio actuator 3 to make it practicable to sense any abnormality in case the seat of the spill valve 2 bites in foreign matters. At the time abnormality being sensed, the degree of opening of the spill valve 2 is increased to allow exhaustion of the foreign matters.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling a fuel injection pump of an internal combustion engine.
In particular, the present invention relates to a method of controlling a fuel injection pump with an improved fuel pumping mechanism.

[Conventional technology]

Conventionally, in a fuel injection pump, the amount of fuel pumped to an injection valve is adjusted by the amount of relief from an on-off valve that communicates with a pressure chamber (for example, a spill valve that operates a hydraulic main valve by a solenoid sub-valve). If a foreign object gets caught in the on-off valve (for example, the above-mentioned main valve) especially during the maximum injection amount such as during cranking, the on-off valve will not lift sufficiently at the maximum injection amount, resulting in the on-off valve lift. Sometimes, it is not possible to secure enough fuel meteor to flush out the foreign matter, resulting in problems such as an inability to start the engine.

[Problem that the invention seeks to solve]

The present invention has been made to solve this problem, and the injection pump is provided with a means (for example, a piezo actuator) for detecting the pressure in the pressure chamber, and the detected pressure reaches a predetermined pressure at a predetermined phase. If not, it is determined that a foreign object is trapped, and the on-off valve is opened early to lift the on-off valve and allow the foreign object to flow out.

[Means for solving problems]

In order to solve the above problems, the present invention provides a fuel injection pump that adjusts the amount of fuel pumped to the injection valve based on the amount of relief from the on-off valve that communicates with the pressure chamber. Provided is a method for controlling a fuel injection pump for an internal combustion engine, comprising: a means for detecting a pressure; and when the detected pressure does not reach a predetermined value at a predetermined time, an amount of relief from the on-off valve is increased. .

[For production]

According to the above configuration, when the detected pressure does not reach a predetermined value at a predetermined time, the amount of fuel relief from the on-off valve is increased, thereby ensuring a sufficient fuel flow rate to drain the foreign matter. Ru.

〔Example〕

FIGS. 1(A) and 1(B) show the main parts of a distribution pump 1 as an example of an injection pump to which the present invention is applied, and the pump 1 includes, as a device unique to the present invention, A solenoid spill valve 2 and a piezo injection rate actuator 3 are installed.

First, the basic structure of the distribution pump 1 will be explained. The pressure chamber 4 performs a stroke of suction and pressure feeding of fuel by the reciprocating movement of the plunger 5.

Fuel is sucked into the pressure chamber 4 through the pump chamber 6, the suction passage 7, the suction port 9 provided in the cylinder 8, and the suction group 10 provided in the plunger 5, and then flows through the discharge passage 11 provided in the plunger 5, and the suction group 10 provided in the plunger 5. It reaches the injection valve 16 through the distribution port 12 which is an opening, the distribution passage 13, the delivery valve 14, and the injection steel pipe 15. The plunger 5 has a reciprocating motion as well as a rotational motion in synchronization with the engine's camshaft.If the engine is a 4-cylinder engine, the plunger 5
makes four reciprocating movements during one rotation. 16a is a cam plate for this purpose, and 17 is a roller. There are four suction groups 1o at equal intervals, and when the plunger 5 moves to the left, one of the suction groups 10 is connected to the suction port 9.
2111, when the plunger 5 moves to the right, none of the suction groups 1o is electrically connected to the suction port 9. There is only one distribution boat 12, but the distribution passage 1
3 are arranged at equal intervals, and when the plunger 5 moves to the right, one of the distribution passages 13 is brought into conduction with the distribution port 12. The inside of the pump chamber 6 has a sufficiently large volume, and a feed pump (not shown) pumps 4 to 10 kg into the pump chamber 6.
g/cut of fuel or full. The feed pump is also incorporated into the injection pump 1 and is driven by a drive shaft for rotating the plunger 5. Next, the spill valve 2 will be explained.

The spill valve 2 includes a main valve mechanism 18 and a pilot valve mechanism 19.
It consists of two mechanisms. The main valve mechanism 18 moves the main valve 21 up and down using the hydraulic pressure in the control hydraulic chamber 20, and connects and disconnects the spill port 22 and the suction passage 7. The spill port 22 is always in communication with the pressure chamber 4 regardless of the position of the plunger 5 due to an axial groove 23 provided inside the cylinder 8 . Main valve 21
is a bullet-shaped lower end having a conical shape, and the conical lower end fits into the spill port 22 to block the spill port 22 and the spill passage 24.

The spill passage 24 includes an enlarged diameter portion 26 at the lower end of the cylinder 25 in which the main valve 21 slides, an obliquely upward passage 27, an annular passage 28 provided at the lower end of the pilot valve mechanism 19, and a spill valve. 2 into the injection pump 1, its tip hits the gasket 29, creating an annular space 31 in the JH portion of the casing 30, an obliquely downward passage 32 that connects the annular passage 28 and the annular space 31, and an annular space 31. It is composed of an obliquely downward passage 33 that connects the suction passage 7 with the suction passage 7. An O-ring 34 is used in the annular space 31 for liquid sealing. The main valve 21 is urged downward by a coil spring 35 so as to shut off the spill port 22 and the spill passage 24 . The upper end of the coil spring 35 is supported by the lower end surface of the pilot valve mechanism 19. Inside the cylinder 25, above the main valve 21 is a control hydraulic chamber 20.
This control hydraulic chamber 20 is always in communication with the pressure chamber 4 through a thin through hole 36 provided at the axis of the main valve 210. The upper end of the cylinder 25 is a pilot valve mechanism 19
The pilot valve mechanism 19 confines the hydraulic pressure in the control hydraulic pressure chamber 20 or releases it to the atmospheric pressure side, for example, the fuel tank 37. The pilot valve mechanism 19 includes a valve needle 38, a valve body 39, and a solenoid 40, which are housed in the casing 30 together with the main valve mechanism 18. The lower end surface of the pilot valve mechanism 19 described above corresponds to the lower end surface of the valve body 39. At the axis of the valve body 39, from the top to the middle,
There is a through hole 41 with a diameter varying from large to small, and a valve needle 38 slides up and down inside the medium hole 42. When the valve needle 38 is at the lower end, the small diameter hole 43 is closed by the lower end of the valve needle 38, and the large diameter hole 44 and the small diameter hole 43 are closed.
is blocked. The small diameter hole 43 opens at the lower end surface of the valve body 39 and communicates with the control hydraulic chamber 2o. An armature 45 is formed at the upper end of the valve needle 38, and the armature 45 is urged downward by a coil spring 46, and the valve needle 38 can only be moved upward when the solenoid 40 is energized. A chamber 47 above the armature 45 that accommodates the coil spring 46 is communicated with the fuel tank 37 through a nipple 48 provided at the upper end of the casing 3o. Although the valve needle 38 and the armatinia 45 are cylindrical, both have flat portions in the axial direction, and the large diameter hole 44 and the chamber 47 are always in communication with each other. Therefore, when the solenoid 4o is energized, the valve needle 38 moves upward, and the control hydraulic chamber 20 is brought into communication with the fuel tank 37 via the small diameter hole 43, the large diameter hole 44, and the chamber 47. The small diameter hole 43 has a larger diameter than the through hole 36 and a smaller diameter than the spill port 22. For example, the diameters are a spill port of 21 m, a through hole of 0.4 mm, and a small diameter hole of 0.8 mii. The diameter of the main valve 21 is 81 cm. Also, the biasing force of the coil spring 35 is 2 kg. Now, assume that the plunger 5 is moving to the right, the pressure chamber 4 is in the pressure stroke, and the solenoid 40 is not energized. At this time, the pressure in the pump chamber 6 is set to 5 kg/ctl, and the pressure chamber 4 is
The pressure is 180 kg/cut.

Since the pressure in the pressure chamber 4 is transmitted to the control hydraulic chamber 20 through the through hole 36, the pressure in the control hydraulic chamber 20 is also 180 kg/ctA. Since the pressure in the pump chamber 6 is transmitted to the enlarged diameter portion 26 via the spill passage 24,
The pressure in the enlarged diameter section 2G is also 5 kg/cl. Therefore, the force Fu acting upward on the main valve 21 is Fu = IROkg/cnfX-(Q, 2)2cn(
+ 5 kg/cn (x The force Fd acting downward on the main valve 21 is Fd = 2 kg + 180 kg
/cfflX (0,8)"cni=92kgFd is 84kg larger than Fu, and this 84kg force pushes the main valve 21 downward and blocks the spill port 22 and spill passage 24.The pressure chamber 4 is necessary for injection. When the desired amount of fuel has been pumped, the valve needle 38
In order to move the
When power is applied to O, the pressure in the control hydraulic chamber 20 is released to the atmosphere, and at this instant, the main valve 21 is pushed upwards by a force of 6 kg, and as a result, the spill port 22 and spill passage 24
The pressure in the pressure chamber 4 is connected to the pump chamber 6.
The pump is opened inside and the pumping process is completed. After this, the plunger 5 continues to move to the right until it reaches a predetermined position, but the pressure chamber 4 only returns fuel to the pump chamber 6 and does not perform a pressure stroke. In order to supply an appropriate amount of fuel to the injection valve 16 according to the operating conditions (engine speed, accelerator opening, etc.), the solenoid 40 is energized at a timing preset for each operating condition. A gap sensor 60 is used to detect this period, which will be described later. Next, the piezo injection rate actuator 3 will be explained. The cylindrical casing 50 is coaxially opposed to the cylinder 8 and is screwed into the injection pump 1. The inner diameter of the casing 50 is one size larger than the inner diameter of the cylinder 8.
1. A piezo actuator 52 is housed. The right end surface of the cylinder 8 and the left end surface of the gauging 50 are in close contact to form a liquid seal, but just to be sure, the outer diameter of the casing 50 is made larger than the outer diameter of the cylinder 8, and an O-ring 53 is used. There is. The piston 51 is slidable in the axial direction within the casing 50 and receives a force in the right direction by the disc spring 54 and the hydraulic pressure in the pressure chamber 4, and a force in the left direction by the piezo actuator 52. The disc spring 54 is supported at the right end of the cylinder 8. The piezo actuator 52 is made into a columnar shape by laminating 80 disk-shaped piezo elements each having a diameter of 15 mm and a thickness of 0.5 m. Copper foil or conductive paint as electrodes is interposed between the piezo elements, so that the piezo elements are electrically parallel to each other, and the two terminals 55 and 56, which are opposite poles, protrude from the casing 50. ing.

The piezo element receives pressure in the thickness direction and generates a voltage in the thickness direction. For example, when the pressure inside the pressure chamber 4 is 200
kg/cl (5 between both terminals 55 and 56 at D)
A voltage of 00 V is generated. Furthermore, if both electrodes of a piezo element that is generating a voltage of 500 V in the thickness direction are short-circuited to release the charge, the thickness of the piezo element becomes 0.5 It m smaller than before the short-circuit. In other words, the total length of the piezo actuator 52 as a whole is reduced by 40 I1 m. When the opening pressure of the injection valve 16 is 160 kg/cJ, the voltage between both terminals 55 and 56 of the piezo actuator 52 is 40 kg/cJ.
If both terminals 55 and 56 are short-circuited immediately after the voltage exceeds 0 V, the pressure inside the pressure chamber 4 will decrease to 1.
60 kg/cn! As the piezo actuator 52 contracts, the pressure inside the pressure chamber 4 drops to about 100 kg/cra.

This causes a temporary pause period in the injection from the injection valve 16, and an injection rate pattern called pilot injection, split injection, or two-stage injection that can reduce combustion noise can be realized. The short-circuited state of both terminals 55 and 56 continues until the plunger 5 is located at the leftmost position (ie, at the end of the suction stroke), at which point the terminals 55 and 56 are brought into an open state.

Note that for the control described later and the control of the spill valve 2 described above, it is necessary to detect the current position of the plunger 5, and the gap sensor 60 is used for this purpose. Gap sensor 60 is attached to the casing of injection pump 1 so that its axis is perpendicular to plunger 5 . A taper 61 is provided in a portion of the plunger 5 perpendicular to the axis of the gap sensor 60, so that the amount of gap detected by the gap sensor 60 varies sharply depending on the position of the plunger 5.

FIG. 2 is a timing diagram illustrating the operation of the injection pump shown in FIG.
Indicates an output of 0. The baseline indicates the case where the plunger 5 is at the left end, and the peak indicates the case where the plunger 5 is at the right end. Time passes toward the right of the diagram. B) shows the voltage applied to the solenoid 40. The baseline is the voltage Ov, that is, the state of non-current, and the upper line is the battery voltage, for example 1
．． It is in a state of 2 V. C) shows the pressure state of the pressure chamber 4. The baseline is the pressure in the pump chamber 6, which varies depending on the engine speed, but is 4 to 10 kg/c
d, and the peak value is around 200 kg/ctJ. D) shows the voltage of the vinyl actuator 52. The baseline is Ov, and the peak voltage 2 is 400.

Figure 2 shows three consecutive cycles (IL (2L (3)
The operation of the injection pump 1 and a computer (not shown) are shown, and (1) and (3) are normal, and (2) is abnormal. First, in the cycle (1), the plunger 5 starts moving to the right at the time θ1.

Along with this, the pressure in C) and the voltage in D) increase.

At θ2 when the output of A) reaches L+, the computer compares the voltage of D) with the reference voltage ■, and if the voltage at θ2 is greater than Vl, this is normal and there is no difference at θ2. Neither. When the voltage of D) rises to ■2, the computer detects it at that time θ, and sets the vinyl actuator 1.
The terminals 55 and 56 of the ether 52 are short-circuited. Therefore, D
) becomes 0 at θ3. Piezo actuator 52
When the voltage drops from V2 (-400V) to O, the voltage is reduced by about 30 μm, and the volume of the pressure chamber 4 is instantaneously expanded, resulting in a pressure drop as shown in C). Therefore, it is possible to realize a pilot injection mode in which the injection valve 16 closes immediately after opening. After that, the combiator energizes the solenoid 40 at time 04 when the output of the gap sensor 60 increases to 1 and 2. After a time delay of θ, the pilot valve mechanism 19 opens, followed by the main valve mechanism 18, and part of the fuel in the pressure chamber 4 is transferred to the pilot valve mechanism 1.
9 to the fuel tank 37, mostly through the main valve mechanism 1.
8 to the pump chamber 6, and the pressure in the pressure chamber 4 is reduced to the same pressure as the pump chamber 6. The output 2 of the gap sensor 60 for determining the timing θ4 for energizing the solenoid 40 is based on the engine operating conditions (speed,
(accelerator opening, etc.) and is stored in the computer. Therefore, the value of I7□ varies depending on the operating conditions at that time. Thereafter, the output of A) passes the peak and drops, and at time θ5 when it reaches L, the energization to the solenoid 40 is stopped F. After a short time delay from θ5, the pyro throat valve mechanism 19 closes, followed by the main valve mechanism 18. The above is the normal operation, but next, the abnormal operation will be explained using (2). When an abnormality occurs, a small foreign object is detected in the main valve 21 of the spill valve 2.
In this case, the pre-nosier chamber 4 remains in communication with the pump chamber 6 via the spill port 1-22, and the plunger 5 Even if it moves to the right, the pressure in the pressure chamber 4 does not increase. In this case, the computer generates a voltage D) of the piezo actuator 52 at θ2.
An abnormality is detected when ① is smaller than 1, and the solenoid 40 is immediately energized at θ2. When the pilot valve mechanism 19 opens as a result, the force Fu acting upward on the main valve 21 is reduced to at least the feed pressure (5
kg/col) x Main valve pressure receiving area (-(0,8)2
), which is about 2.5 kg, but the force Fd acting downward on the main valve 21 is the force of the coil spring 350.
2 kg, the main valve 21 is raised by a force of 0.5 kg, and the foreign matter is flushed into the pump chamber 6 by the action of fuel discharge from the pressure chamber 4. Therefore, in the next cycle (3), normal operation resumes. Here, the foreign matter cannot be washed away unless the pilot valve mechanism 19 is opened because the biting force is applied by the 2 kg force of the coil spring 35, and if you wait until θ4, the solenoid 40 is energized. The reason why the current is applied at θ2 even though it is removed is to increase the fuel flow rate to wash away foreign matter. Foreign objects are likely to get caught at low speeds such as when the engine is cranking, and at such times θ4 is the plunger 5.
is almost at the right end, and it is not possible to secure enough fuel flow to wash away the foreign matter.

A flowchart of the above operation is shown in FIG. here"
"I, interrupt" means that a trigger is generated every time the amount of change in the output of the gap sensor 60 reaches a certain set amount, and an interrupt is performed based on this trigger. Generally known techniques may be used for how to put out these 1-Riga.

FIG. 4 shows another example of an injection pump to which the present invention is applied. Although an angle sensor and a reference sensor can be used to detect the position of the plunger 71, the above-mentioned gap sensor can also be used to detect the position of the plunger 71. The operation timing in that case is shown in FIG. (1) and (3) are normal, and (2) is abnormal. A) shows the output of the gap sensor.

A'), the annular groove 78 of the plunger 71 and the cylinder 72
The opening area of the port through which the opening lower 7 communicates is shown. What was in communication at the time θ1 when the plunger 71 starts its rightward movement from the left end is θ1 at the beginning of the rightward stroke of the plunger 71.
Communication is cut off at 6.

Further, B') shows the trigger voltage for turning on the thyristor 88 (see the piezo actuator 740 control circuit shown in FIG. 5). In other words, 1 at the time of θ3 and θ4
A trigger pulse of about 00 μsec is generated. Also, B″) shows the timing when the transistor 85 turns on.During this time, the current from the battery 81 flows through the primary winding 83 of the transformer 820, and at θ7, the current in the primary winding 83 is cut off. A high voltage of 500 cm is generated in the secondary winding 84, and this voltage is applied to the piezo actuator 7 via the diode 86.
4 and extends it.

C) shows the pressure in the pressure chamber 73. At a time θ3 when the pressure in the pressure chamber 73 slightly exceeds the opening pressure of the injection valve, the thyristor 88 is turned on, short-circuiting the piezo actuator unit 4 through the coil 87 and contracting it, and as a result, the pressure The pressure in the pressure chamber 79 decreases and the valve needle 75 lifts to bring the pressure chamber 73 into communication with the low-pressure pump chamber 69, so the pressure in the pressure chamber 73 suddenly decreases and falls below the closing pressure of the injection valve, causing injection. will be temporarily suspended. Immediately thereafter, at θ7, the piezo actuator 74 extends again and the valve needle 75 is seated on the valve seat 76 again, so that the pressure in the pressure chamber 73 rises again and the injection is restarted. Therefore, a form of pilot injection is established. At θ4, the vinyl actuator 'Unitough 4 contracts again, and the pressure chamber 7
The pressure at No. 3 decreases and the injection ends.

D) shows the voltage of the piezo actuator 74.

As the plunger 71 rises, the pressure chamber 73
The pressure increases, and since the control pressure chamber 80 and the pressure chamber 73 from θ1 to θ6 are electrically connected, the piezo actuator 74 generates a voltage proportional to the pressure in the pressure chamber 73. This voltage is compared with the reference voltage V1 at the time of θ2, which is slightly earlier than θ6, and if the voltage is higher than 1, it is normal and no control is performed at θ2. This is (1) in Figure 6. In (1), the piezo actuator 74 is turned on by turning on the thyristor 88 at θ1 immediately after the time θ6 when the opening area of the port (FIG. 6 A') becomes O (FIG. 6 B'). It is contracted by releasing the charge and bringing the potential to O. Thereafter, at θ, the transistor 85 is turned off (FIG. 6B"), and a high voltage is applied to the piezo actuator 74 to cause it to expand. At θ4, the thyrisk 88 is turned ON again (FIG. 6B"), and the piezo actuator 74 is expanded. The charge on actuator 74 is discharged, causing it to contract. Next, an abnormal case will be explained with reference to FIG. 6 (2). This is the case when the voltage of the piezo actuator 74 is smaller than the reference voltage ■1 at θ2, and at this time, the transistor 85 is turned off at θ2.
FF (Fig. 6B") and apply a high voltage to the piezo actuator 74 to make it expand. Then, at θ3, turn on the thyristor 88 as in the normal case (Fig. 6B").
') to contract the piezo actuator 74. What is important here is to apply a high voltage to the piezo actuator 74 at θ2, so if the Cyrisk 88 is turned on at θ1, the charge is released and the piezo actuator 74 is contracted. It can be done. In the case of normal (1) above, no high voltage is applied at θ2.

Also, since an electric charge proportional to the pressure (C) of the pressure chamber 73 is generated, by short-circuiting at θ3, this electric charge can be released and the piezo actuator 74 can be contracted. However, in the abnormal case (2) above, a foreign object is caught between the valve seat 76 and the valve needle 75 and the pressure in the pre-nocha chamber 73 does not increase, so a charge is generated in the piezo actuator 74 due to the pressure. ,
-1! However, it cannot be contracted simply by short-circuiting at θ3.

FIG. 7 shows a flowchart for the above operation.

〔Effect of the invention〕

According to the present invention, it is possible to reliably flush out foreign matter stuck in the on-off valve (for example, the main valve) that communicates with the pressure chamber in each operating cycle, and to prevent foreign matter from becoming impossible to start, especially during cranking. You can eliminate the problem.

[Brief explanation of the drawing]

FIG. 1(A) and FIG. 1(B) are cross-sectional views showing one example of a fuel injection pump to which the present invention is applied, and FIG.
3 is a flowchart illustrating the control operation of the fuel injection pump shown in FIG. 1, and FIG. 4 is a timing diagram illustrating the operation of the fuel injection pump shown in FIG. 5 is a circuit diagram showing an example of a control circuit used in the fuel injection pump shown in FIG. 4; FIG. 6 is a sectional view showing another example of the fuel injection pump shown in FIG. 7 is a flowchart showing the control operation of the fuel injection pump shown in FIG. 4. FIG. (Explanation of symbols) 2... Solenoid spill valve, 4... Pressure chamber, 5... Plunger, 6... Low pressure pump chamber, 1
6... Injection valve, 18... Main valve mechanism, 1
9... Pilot valve mechanism, 40... Solenoid, 52... Piezo actuator, 60... Gap sensor, 69... Low pressure pump chamber, 71... Plunger, 73
...Pressure chamber, 74...Piezo actuator, 75...Valve needle, 79...Pressure chamber.

Claims (4)

[Claims] 1. A fuel injection pump configured to measure the amount of fuel pumped to an injection valve based on the amount of relief from an on-off valve communicating with a pressure chamber is provided with means for detecting the pressure of the pressure chamber, and the detected pressure is detected at a predetermined time. 1. A method for controlling a fuel injection pump for an internal combustion engine, characterized in that when the amount of relief from the on-off valve is increased when the amount of relief from the on-off valve is increased. 2. 2. The method of controlling a fuel injection pump according to claim 1, wherein a piezo actuator is used as the pressure detection means. 3. When a solenoid type on-off valve is used as the on-off valve and the detected pressure does not reach a predetermined value at a predetermined time,
The method of controlling a fuel injection pump according to claim 1, wherein the solenoid-type on-off valve is immediately opened. 4. If the detected pressure does not reach a predetermined value at a predetermined time, a high voltage is immediately applied to the piezo actuator to expand it, and then the piezo actuator is short-circuited to contract it. range 2nd
A method of controlling a fuel injection pump described in Section 1.