JPS5932633A - Fuel injection controlling apparatus for diesel engine - Google Patents

Abstract

PURPOSE:To enable to control fuel injection of a diesel engine according to the operational conditions of the engine, by providing a fuel return passage connecting a pressure chamber for pressurizing fuel to a fuel tank and a solenoid valve for opening and closing said fuel return passage, and driving a sleeve for opening and closing the fuel return passage by means of an electric actuator. CONSTITUTION:By the movement of a cam disk 33, a plunger 38 is at first moved in the direction shown by an arrow P in the drawing and pressure in a pressure chamber 42 is raised through reduction of its volume. During the while when current is supplied to a coil 58 of a solenoid valve 55, however, a plunger 57 is moved in the direction of an arrow S against the restoring force of a compession coil spring 56, so that a poppet valve 54 is opened. Resultantly, fuel in the pressure chamber 42 is released to a fuel tank via the poppet valve 54, a valve 41 and a fuel return passage 52, so that pressure in the pressure chamber 43 is not raised so much and does not become higher than the set pressure of a delivery valve 40.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control device for controlling fuel injection timing and injection amount in a distributed fuel injection pump for a diesel engine.

A conventional distribution type fuel injection pump for a diesel engine is generally constructed as shown in FIGS. 1 and 2.

Such a fuel injection pump is also described, for example, on pages 193 to 195 of "Automotive Engineering Zensho Vol. 5" published by Sankaido Co., Ltd., but this will be briefly explained.

In FIG. 1, fuel is drawn from an inlet 1 of the pump body by a feed pump 3 driven by a drive shaft 2. In FIG.

The fuel discharged from the feed pump 3 is supplied to a pump chamber 5 inside the pump housing after the supply pressure is controlled by a pressure regulating valve 4.

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 cylinders of the engine, and reciprocates by a predetermined cam lift while rotating over a roller 11 (see also FIG. 2) pivotally supported by a roller ring 10.

Therefore, the plunger 7 does not rotate but reciprocates, and as a result of this reciprocating movement, the fuel sucked from the suction port 12 is pressurized in the pressure chamber 17 and sequentially transferred from the distribution port 13 corresponding to each cylinder. It passes through the delivery valve 14 and is force-fed to the injection nozzle of each cylinder (not shown).

The amount of fuel to be injected is determined by the position of the sleeve 16 formed in the plunger 7 and covering the spill port 15, which is a fuel relief passage.When the spill port 15 opens by moving the plunger 7 to the right, the inside of the pressure chamber 17 is determined. The high-pressure fuel is released into the inside of the pump housing 5, and the pumping is completed.

The position of the sleeve 16 is determined by the movement of the governor mechanism 18 driven by the rotation of the drive shaft 2.
9, and the fuel injection amount 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.

To this end, as clearly shown in Figure 2, Laura Lang 1
0 is swingably connected to a plunger 21 via a driving pin 20.

The fuel pressure in the pump chamber 5 is introduced to the end face height 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. Although the state is close to pressure, the elastic force of the spring 26 pushes the plunger 21 back two degrees.

Therefore, as the rotational speed of the engine 5 increases, the fuel pressure in the pump chamber 5 increases, so the plunger 21 shown in FIG. Since it is rotated in the direction of arrow B), the fuel injection timing relative to the engine crank angle is advanced.

When the engine speed decreases, the fuel pressure in the pump chamber decreases, so the plunger 21 moves to the right due to the force of the spring 26, rotating the roller ring 10 in the same direction as the rotational direction of the eccentric disk 8, contrary to the above. Since the fuel injection timing is moved, the fuel injection timing is delayed.

Note that FIG. 1 shows a state in which the axis of the plunger 21 is rotated by 90 degrees. Similarly, for convenience of explanation, a vertical section of the feed pump 3 and a cross section obtained by rotating its axis by 90 degrees are shown together in FIG.

In this way, the fuel injection timing and injection amount in a conventional general distribution fuel injection pump are controlled by rotating the roller ring by moving the plunger 21 according to the engine rotation speed and by the action of the governor mechanism 18. This is done by moving the position of the sleeve 16 via the link lever 19, which not only makes the mechanism complicated, but also makes it difficult to control the fuel injection timing and injection amount to always be optimal according to the operating conditions of the engine. I couldn't do it.

Therefore, a plunger (
It has also been proposed to install a solenoid valve and its controller to control the hydraulic pressure acting on the piston, and to control the opening and closing of the solenoid valve according to operating conditions such as engine speed and load (for example, Japanese Patent Publication No. 56-53089). reference).

However, this is only an electric method for controlling the conventional plunger hydraulic pressure, and the complicated mechanism of the plunger, roller ring, eccentric disc, etc. remains, and not only is it impossible to reduce costs, but it is also difficult to reduce costs.
It was also insufficient in terms of accuracy and responsiveness.

Additionally, the applicant has previously proposed that the position of the sleeve 16 for controlling the fuel injection amount be controlled by an electric signal using a torque motor and a feed screw mechanism. The amount of fuel injection was also not optimally controlled.

This invention was made by focusing on the problems in the fuel injection timing and injection amount control device in the conventional distribution type injection pump for diesel engines. The purpose of this invention is to enable control of optimal fuel injection timing and injection amount.

Therefore, the fuel injection control device according to the present invention is provided with a fuel return passage that communicates a pressure chamber in which fuel is pressurized by a plunger with a fuel tank, a solenoid valve that opens and closes this passage, and a sleeve that opens and closes a fuel relief passage of the plunger. is driven by an electric sleeve actuator, and the electromagnetic valve and the sleeve actuator are controlled respectively in accordance with the fuel injection timing and fuel injection amount calculated based on the operating conditions of the engine.

Embodiments of the present invention will be described below with reference to FIG. 3 and subsequent figures of the accompanying drawings.

FIG. 3 is a longitudinal cross-sectional view showing an example of a mechanical part of a distribution type fuel injection pump and its fuel injection control device embodying the present invention.

In the figure, a drive shaft 31 is driven by an engine at half the rotation speed of its crankshaft, thereby rotating a foot pump 32 and a cam disc 33.

The feed pump 32 increases the pressure of the fuel flowing in from the fuel inlet 34 and sends it into the pump chamber 30 formed by the case 35 . At this time, the oil feeding pressure is adjusted to a constant level by the regulating valve 36.

The cam disc 33 is rotatably mounted on the drive shaft 31 in a rotational direction and slidable in the axial direction, and has protruding cam surfaces 33a on its circumference, the number of which is the same as the number of cylinders in the engine. is formed and is in contact with a roller 37 rotatably supported inside the case 35, and as the cam surface 33a rotates over the roller 37, it moves in the direction of arrow P.

The plunger 38 includes a fuel inflow passage 39 as in the conventional case.
The same number of suction vertical grooves 38a as the number of cylinders communicate with the cylinders, the discharge lateral grooves 38b communicate with the same number of discharge passages 41 as the number of cylinders that communicate with the injection valves (not shown) via the delivery valves 40, and the fuel relief passage communicates with the pump chamber 30. (spill port) 38c
, and the discharge lateral groove 38b and the fuel relief passage 38c are connected to the pressure chamber 4.
A vertical passage 38d communicating with 2 is formed.

The flange 38 is fixed in the center of the cam disk 33 in the axial direction thereof, and moves in conjunction with the cam disk 33 to perform rotation for fuel distribution and reciprocating motion for sucking and pumping fuel.

A cylindrical sleeve 44 made of a non-magnetic material is slidably fitted into the plunger 38 to open and close the fuel relief passage 38c.

A cylindrical magnet 45 is fitted onto the outer peripheral surface of the sleeve 44, and two driving coils 46 are wound around the outer periphery of the magnet 45 in a cylindrical shape facing each other with a gap therebetween.
, 47 to constitute a sleeve actuator for moving the sleeve 44 in the axial direction of the plunger 38, and a sensor stay 48 is attached to the magnetic pole of the magnet 45 to detect the position of the sleeve 44. Displacement sensor 49 using a magnetic sensor inside the case 35
is installed.

Further, the pressure chamber 4 pressurizes the fuel by the plunger 38.
2 is connected to a fuel tank (not shown) via a fuel return passage 52 in which a check valve 51 is inserted, and is composed of a poppet valve 54 inserted in this fuel return passage 52 and an electromagnetic solenoid 55 for driving the poppet valve 54. Equipped with a solenoid valve.

The electromagnetic solenoid 55 includes a solenoid plunger 57 and a coil 58, which are biased in the direction of arrow R by a compression coil spring 56, and when the coil 58 is energized, the solenoid plunger 57 moves in the direction of arrow S. , the poppet valve 54, which is normally biased from the closed state by the spring 59, is brought into the open state. 60 is a spring that gives the plunger 38 and the cam disc 33 a tendency to return to the left in the figure.

FIG. 4 is a block circuit diagram showing an example of a control section of the fuel injection control device.

In the same figure, an accelerator pedal travel sensor 61, an engine rotation speed sensor 62, a temperature sensor 63, and a crank angle sensor 64 respectively indicate the accelerator pedal travel, engine rotation speed, temperature, and crankshaft reference position as engine operating conditions. The injection timing control circuit 65, which is a well-known sensor that detects and outputs a signal according to the detection result, is a fuel injection timing control means, and is composed of an injection timing calculation circuit 66 and an injection timing determination circuit 67.

The injection timing calculation circuit 66 advances the fuel injection timing based on the accelerator pedal travel a, the engine speed N, and the temperature T detected by the accelerator pedal travel sensor 61, the engine speed sensor 62, and the temperature sensor 63, respectively. θa is calculated and the calculation result is output to the injection timing determining circuit 67.

The injection timing determining circuit 67 determines the engine rotation speed N and the advance angle θa.
, and the reference position θc of the crankshaft detected by the crank angle sensor 64, the injection start timing t
a(ta=f3(θa, N)) is calculated, and the electromagnetic solenoid 55 shown in FIG. 3 is driven and controlled according to the calculation result.

The injection amount control circuit 68 is a fuel injection amount control means and includes an injection amount calculation circuit 69, an injection amount correction circuit 70, and an injection amount determination circuit 71.

The injection amount calculation circuit 69 calculates the fuel injection amount Q based on the accelerator pedal travel α and the engine rotational speed N, and outputs the calculated amount to the injection amount determination circuit 71.

The injection amount correction circuit 70 corrects the injection amount Δ according to the advance angle θa based on the engine rotation speed N and the injection start timing ta.
Q (ΔQ-f4(ta)) is calculated and the calculation result is output to the injection amount determining circuit 71.

The injection amount determining circuit 71 determines the injection amount Q and the correction amount Δ.
The target position S0 (S0-f1
(Q)+f2(JQ)) and outputs the result of the calculation to the servo amplifier 72.

The servo amplifier 72 energizes the coils 46 and 47 forming the sleeve actuator shown in FIG. 3 with an output compensated for the difference between the target position So and the detected position Sd by the displacement sensor 49 shown in FIG.

Note that the injection timing control circuit 65 and the injection control circuit 68 can also be configured by a microcomputer.

Next, the operation of the embodiment configured as described above will be explained. First, the operation of controlling the fuel injection timing of the mechanism block of the fuel injection control device shown in FIG. 3 will be explained.

Due to the rotation and reciprocating motion of the cam disc 33, the plunger 38 first moves in the direction of arrow P, so that the pressure chamber 42
A change in volume (shrinkage) occurs and the pressure increases.

However, while the coil 58 of the electromagnetic solenoid 55 is energized, the solenoid plunger 57 moves in the direction of arrow S against the restoring force of the compression coil spring 56.
The poppet valve 54 is in an open state.

Therefore, the fuel in the pressure chamber 42 is transferred to the bobbet valve 54.
, push open the check valve 51, and open the fuel return passage 5.
2 to a fuel tank (not shown), the output of the pressure chamber 42 does not increase much and does not exceed the set pressure of the delivery valve 40.

Therefore, fuel is not supplied to the injection valve (not shown).

Then, when the power to the coil 58 of the electromagnetic solenoid 55 is cut off while the plunger 38 is moving in the direction of the arrow P,
Since the solenoid plunger 57 moves in the direction of arrow R due to the restoring force of the compression coil spring 56, the pot valve 5
4 is brought into a closed state by the biasing force of the spring 59.

As a result, the fuel in the pressure chamber 42 is pressurized by the plunger 38, and the pressure becomes higher than the set pressure of the delivery valve 40, so that the fuel is supplied to the injection valve (not shown), and the fuel is injected into the corresponding cylinder of the engine. be done.

After the plunger 38 moves a full stroke in the direction of the arrow P, it begins to return in the direction of the arrow Q due to the restoring force of the spring 60, and then the electromagnetic solenoid 55 is energized again to open the poppet valve 54.

By this movement of the plunger 38 in the direction of the arrow Q, fuel is supplied from the fuel inflow passage 39 to the pressure chamber 42, and the operation for one cylinder is completed.

In this way, the poppet valve 54 and the electromagnetic solenoid 5
By driving and controlling the solenoid valve 5, it is possible to control the timing at which pressurization by the plunger 38 starts, that is, the fuel injection timing.

The drive control of this solenoid valve is performed by the injection timing control circuit 6 shown in FIG.
Do it by 5.

That is, as shown in FIGS. 5(a) and 5(b), the injection timing control circuit 65 controls the pressurization by the plunger 38 based on a function of the engine speed N and temperature T (or accelerator pedal travel α). The start time (advance angle θa) is determined, and the electromagnetic solenoid 55 is de-energized at the injection start time ta from the reference position θc of the crankshaft.

Also, based on the reference position θc of the crankshaft and the engine rotation speed N, the timing at which the plunger 38 starts its return movement in the direction of the arrow Q is calculated, and after the plunger 38 starts its stroke in the direction of the arrow Q, it is fully stroked. In the meantime, the electromagnetic solenoid 55 is energized again.

In this way, by starting pressurization by the plunger 38 when the electromagnetic solenoid 55 is de-energized, the influence of the reactance of the coil 58 of the electromagnetic solenoid 55 can be reduced by reducing the effect of the reactance on the coil 58 (not shown). so it can be removed by wheel diode,
Mass of solenoid plunger 57 and compression coil spring 56
By appropriately selecting the setting force, high responsiveness of fuel injection start timing control can be achieved.

In addition, the responsiveness when reenergizing the electromagnetic solenoid 55 does not need to be very high, so the attraction force (force to move it in the direction of arrow S) to the solenoid plunger 57 is only slightly greater than the setting force of the compression coil spring 56. It is possible to achieve miniaturization and power saving.

Next, fuel injection amount control will be described.

When the poppet valve 54 in FIG. 3 is in the closed state and fuel injection is performed by moving the plunger 38 in the direction of arrow P, the fuel relief passage 38 of the plunger 38
c is no longer closed by the sleeve 44, the fuel passes through the vertical passage 38d and from the relief passage 38c to the pump chamber 30.
Therefore, even if the plunger 38 moves further in the direction of the arrow P, the fuel pressure becomes less than the set pressure of the delivery valve 40 and no fuel is injected.

Therefore, by controlling the position of the sleeve 44 by changing the timing at which the relief passage 38c of the plunger 38 opens, that is, the direction and magnitude of the excitation current to the coils 46 and 47, the timing at which the fuel injection ends, that is, the amount of fuel injection can be controlled. can be controlled.

This position control of the sleeve 44 is performed by an injection amount control circuit 68 shown in FIG.

As shown in FIG. 6, it is basically determined by a function of the engine speed N and the accelerator pedal travel α.

Further, the injection amount Q is proportional to the pressurizing stroke of the plunger 38, and when the poppet valve 54 is in the closed state, as shown in FIG. The distance S2 to the right end surface of
The difference from the distance S1 to the right end of the relief passage 38c when the plunger 38 makes a full stroke in the direction of the arrow Q
1).

Therefore, when the poppet valve 54 is in a normally closed state, that is, when the advance angle θa is at its maximum, the injection amount Q is Q-A
(S2-S1) [A: cross-sectional area of the plunger 38], and the injection amount Q can be uniquely changed by changing the distance S2.

On the other hand, when the advance angle θa is smaller than the maximum advance angle, there is a time when the poppet valve 54 opens, so if the stroke amount of the plunger 38 during that time is S3, the injection amount Q is equal to ΔQ-AS83. Because it is insufficient, sleeve 4
There is a spirit that moves the position No. 4 to the right in FIG. 3 by a stroke amount S3.

The injection amount control circuit 68 performs such calculations, and calculates the injection amount Q based on a function of the accelerator pedal travel α and the engine rotational speed N, and converts it into a correction amount S3 for the sleeve 34. , calculates the correction amount ΔQ of the injection amount Q according to the advance angle θa, converts it into S3 for correction of the sleeve 34, and adds the result of S2 and S3 to the target position S of the sleeve 44.
It is output to the servo amplifier 72 as 0.

Thereby, the servo amplifier 72 positions the sleeve 44 by controlling the direction and/or magnitude of the excitation current flowing through the coils 46 and 47 so that the detected position Sd by the displacement sensor 49 coincides with the target position S0.

Note that, although the above-mentioned operation is performed under normal operating conditions, when starting the engine, the position of the sleeve 44 is adjusted so that the injection amount is maximized in order to improve startability.

When the engine is still idling, the set engine speed is used as a target value, and the detected engine speed is fed back so that the engine speed reaches the set value, and the position of the sleeve 44 is adjusted according to the difference.

Furthermore, when the key switch is turned off, the solenoid valve is opened for a certain period of time so that fuel is no longer forced into the injection valve, so the engine can be stopped.

In the above embodiment, an example was described in which the sleeve actuator was configured by a coil and a magnet, but the sleeve position may be controlled by a torque motor or a servo motor.

As explained above, according to the present invention, injection timing control and injection amount control are optimally performed by electric signals using a solenoid valve that controls the fuel pressurization start timing and an electric sleeve actuator that controls the pressurization end timing. As a result, the structure of the mechanism is simplified, and fuel injection can be controlled with high precision and responsiveness, and it is possible to control vibrations unique to diesel engines, purify exhaust gas, and improve fuel efficiency. .

In particular, in the conventional fuel injection pump as shown in FIGS. 1 and 2, a roller ring 10, a driving pin 20 and a plunger for rotating the roller ring 10 are provided to control the fuel injection timing. Since mechanisms such as 21 and the like are not required and only one roller needs to be supported directly on the case, the effect of reducing the number of parts and assembly man-hours is extremely large.

[Brief explanation of drawings]

1 and 2 are a longitudinal cross-sectional view and a cross-sectional view of an injection timing control mechanism portion of an example of a conventional distribution type fuel injection pump for a diesel engine. FIG. 3 is a longitudinal cross-sectional view showing an example of the mechanism of a distributed fuel injection pump and its fuel injection control device for a diesel engine according to the present invention, and FIG. 4 is an example of the control section of the fuel injection control device. 5 and 6 are diagrams for explaining the operations of the injection timing calculation circuit and the injection amount calculation circuit in FIG. 4. FIG. 31...Drive shut 32...Feed pump 33...Cam disc 37
...Roller 38...Plunger 38c...Fuel relief passage 42...Pressure chamber 44...Sleeve 45
...Magnets 46, 47...Electric sleeve actuator drive coil 49...Displacement sensor 52...Fuel return passage 54.
・Electric fuel valve poppet valve 55 ・Electromagnetic solenoid 65 ・Injection timing control circuit 68 ・Injection amount control circuit Fig. 5 ■ Fig. 6

Claims (1)

[Claims] 1 In the distribution type fuel injection pump of diesel engine,
A fuel return passage is provided that communicates the pressure chamber in which the fuel is pressurized by the plunger with the fuel tank, and a solenoid valve that opens and closes this fuel return passage, and an electric sleeve actuator that drives the sleeve that opens and closes the fuel return passage of the forward air plunger. a fuel injection timing control means that calculates a fuel injection timing based on engine operating conditions and controls opening and closing of the solenoid valve according to the calculation result; and a fuel injection timing control means that calculates a fuel injection amount based on the engine operating conditions. , and fuel injection amount control means for controlling the sleeve actuator according to the calculation result and the fuel injection timing.