JPH02294528A - Distribution type fuel injection pump - Google Patents

Abstract

PURPOSE:To protect an engine securely when a supercharger fails by providing an actuator for opening a relief port by the drive signal of a supercharging pressure detector means to lower the fuel pressure in a pump chamber. CONSTITUTION:A timer 6 varies the injection period of fuel according to the fuel pressure in a pump chamber 5. When the supercharging pressure of sucked air exceeds a preset pressure, a boost compensator 7 reduces the amount of fuel to be injected. A supercharging pressure sensor 8 is provided to output a drive signal when the supercharging pressure exceeds the preset pressure. An electromagnetic valve core is provided as an actuator for opening a relief valve 9 by the drive signal to reduce the fuel pressure in the pump chamber 5. Thus, an engine can be protected securely when the waist gate valve, etc., of a supercharger fails.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distribution type fuel injection pump that can be suitably employed in a diesel engine equipped with a supercharger.

[Prior Art] A distribution type fuel injection pump sucks up fuel from a fuel tank using a feed pump built into the pump housing, adjusts the pressure of the fuel according to the engine speed using a regulating valve, and then pumps the fuel into the pump housing. The pump is configured to be pumped into the pump chamber of the pump. In addition, the pump chamber is equipped with a timer that operates according to the fuel pressure.
This timer adjusts the fuel injection timing according to the engine rotation speed.

On the other hand, in engines equipped with a supercharger, when the supercharging pressure exceeds the set pressure, the wastegate valve of the supercharger opens to bypass exhaust gas, but if the wastegate valve etc. malfunctions, It is necessary to reliably protect the engine even if boost pressure increases abnormally. Therefore, the distributed fuel injection pump used in this type of engine is
As prior art of the present invention, for example, JP-A-60-201
As shown in Publication No. 029, when the supercharging pressure of intake air exceeds the set pressure, the relative position between the pump plunger and the spill ring is changed by the boost compensator,
Many vehicles employ a structure (OLP: overload protector) that reduces the amount of fuel injected.

[Problems to be Solved by the Invention] However, as schematically shown in FIG. (OLP operation), the cylinder pressure decreases only slowly and remains high for a while. In addition, if boost conventor abnormalities occur together, there is a risk that the fuel injection amount will not be fully reduced, which is insufficient to reliably protect the engine in the event of a failure of the supercharger's wastegate valve, etc. It is.

The present invention aims to solve such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a timer that changes the fuel injection timing according to the fuel pressure in the pump chamber, and a timer that changes the fuel injection timing according to the fuel pressure in the pump chamber, and In the distribution type fuel injection pump, which is equipped with a boost compensator that changes the relative position of the pump plunger and the spill ring to reduce the fuel injection amount when the boost pressure of intake air is -1- below the set pressure. The pump is characterized in that it includes a supercharging pressure detection means that outputs a drive signal when the pump rotates, and an actuator that opens a relief port based on the drive signal and lowers the fuel pressure in the pump chamber.

According to Yokinari, when the supercharging pressure of intake air exceeds the set pressure, the boost compensator changes the relative position of the pump plunger and spill ring in the direction of decreasing fuel, causing fuel to flow into the combustion chamber. The fuel injection amount is reduced.

Further, when the supercharging pressure of the intake air exceeds the set pressure, a drive signal is manually applied to the actuator from the supercharging pressure detection means. When a drive signal is input to the actuator, this actuator opens a relief port and relieves the fuel in the pump chamber, so that the fuel pressure in the pump chamber decreases. Then, when the fuel pressure in the pump chamber decreases, the timer operates to the retard side in accordance with the decrease in fuel pressure, and the fuel injection timing is delayed from the predetermined set timing.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 4.

The distribution type fuel injection pump schematically shown in FIG. 1 is installed in a diesel engine equipped with a supercharger (not shown), and includes a feed pump 2 built into a pump housing 1,
A spill ring 4 that is slidably attached to the pump plunger 3, a timer 6 that changes the fuel injection timing according to the fuel pressure in the pump chamber 5, and a timer 6 that changes the fuel injection timing according to the fuel pressure in the pump chamber 5, and A boost compensator 7 that reduces the fuel injection amount, a boost pressure sensor 8 that is a boost pressure detection means that outputs a drive signal a when the boost pressure exceeds a set pressure, and a relief port that detects the drive signal a based on the drive signal a. 9 is opened and is provided with a solenoid valve 10 serving as an actuator for lowering the fuel pressure in the pump chamber 5.

As schematically shown in FIG. 2, the feed pump 2 is configured such that a rotor 2b provided with a plurality of blades 2a is driven by a drive shaft 11, and the fuel pumped up from the fuel tank is pumped through a regulating valve l2. It is configured such that the liquid is fed under pressure to the pump chamber 5 via the pump chamber 5.

The regulating valve 12 includes a piston 12b and a valve spring 12c that biases the piston 12b toward the closing side in a cylinder 12a, and is interposed in the discharge passage 2C of the feed pump 2. . Then, the feed pump 2
By adjusting the amount of fuel released into the suction passage 2d, the pressure of the fuel pumped from the feed pump 2 to the pump chamber 5 is adjusted.

As schematically shown in FIG. 2, the timer 6 includes a timer piston 6a slidably housed in a timer housing;
The timer spring 6b is provided in elastic contact with one end of the timer piston 6a, and the fuel pressure on the suction side of the feed pump 2 is introduced into one end of the timer piston 6a, and the fuel pressure in the pump chamber 5 is introduced into the other end. pressure is introduced. The timer piston 6a is connected to a roller ring 13 disposed on the outer peripheral side of the drive shaft 11 via a slide pin 6c. The roller ring 13 is held in the pump housing 1 in a state where it can rotate within a certain range in the direction around the axis.
It has the same number of rollers 13a as the number of cylinders. Then, when the cam plate 14 having the same number of face cams as the rollers 13a rotates in the same direction as the drive shaft 11 while being attached to the rollers 13a, the pump plunger 3 reciprocates while rotating. The fuel in the pump chamber 5 is sucked into the pressure chamber 5a, and the fuel is distributed and pressure-fed to each randomly disposed fuel injection valve 15 through the respective distribution passage 16.

When the fuel pressure in the pump chamber 5 acting on the timer 6 increases, the timer piston 6 responds to the increase in fuel pressure.
As a is displaced, the roller ring 13 is rotated by the slide bin 6c in a direction opposite to the drive shafts 1 and 11, that is, to the advance side F within a predetermined range. When the roller ring 13 rotates to the advance side F, the holding position of each roller 13a changes, so that the fuel injection timing is advanced.

On the other hand, when the fuel pressure in the pump chamber 5 decreases, the timer piston 6a is pushed back by the timer spring 6b in response to the decrease in fuel pressure, and the roller ring 13 is moved in the same direction as the drive shaft 11 via the slide pin 6c, that is, It is designed to be rotated to the retard side L within a predetermined range. When the roller ring 13 rotates to the retard side L, the holding position of each roller 13a changes, and the fuel injection timing is delayed.

The boost compensator 7 has a push rod 7a connected to a diaphragm (not shown) or the like, and communicates a pressure chamber with an intake passage on the downstream side of the supercharger. The tip of the push rod 7a has a reverse tapered portion 7b that expands toward the proximal end.
, and its inversely tapered portion 7b is connected to the pump chamber 5.
The connecting pin 17 is engaged with the connecting bin 17 in the desired direction. The connecting pin 17 is fixed to one end of a control arm 19 that rotates within a certain range around a shaft 18 fixed to the pump housing 1, and the other end of this control arm 19 is connected to a tension lever. It is engaged with one end of 20. The tension lever 20 is rotatable within a certain range around a common shaft 23 fixed on a guide lever 22 along with a control lever 21, and the tip of the control lever 21 is joined to the spill ring 4. There is.

The boost pressure sensor 8 closes the power supply circuit 24 when the boost pressure of intake air exceeds a set pressure (for example, 600a+mHg).
It is configured to open the power supply circuit 24 when the pressure falls below a set pressure, and is attached to an intake manifold (not shown) on the downstream side of the supercharger.

The electromagnetic valve 10 is connected to a power source 25 via the boost pressure sensor 8, and includes a valve body 10a, an electromagnetic coil 10b, and the like. When the drive signal a is not applied to the electromagnetic coil 10b, the relief port 9 is closed by the valve body 10a, and when the drive signal a is applied to the electromagnetic coil 10b, the valve body 10a is excited and the relief port 9 is closed. It is designed to be developed. The relief port 9 opens into the pump housing 1 near the throttle 26 and has a larger diameter than the throttle 26, and communicates with the throttle 26 through an overflow pipe 27 to a fuel tank (not shown).

According to such a configuration, when the supercharging pressure of the intake air goes around the set pressure by -[-, the push rod 7a of the boost compensator is displaced in the direction of fuel reduction (arrow A), so that the connecting part that engages with the reverse tapered part 7b The control arm 19 is rotated counterclockwise (in the direction of arrow B) about the shaft 18 by the pin 17. When the control arm 19 rotates counterclockwise, the tension lever 20 and the control lever 21 rotate clockwise (in the direction of arrow C) about the shaft 23, so that the pump plunger 3 moves in the fuel decreasing direction (in the direction of arrow D). ). Therefore, the effective stroke from the start to the end of fuel pumping by the pump plunger 3 becomes smaller, the fuel injection amount is reduced, and the combustion pressure is lowered.

Furthermore, when the supercharging pressure of the intake air exceeds the set pressure, the supercharging pressure sensor 8 causes the power supply circuit 2 to
4 is closed and the drive signal a is applied to the electromagnetic valve 10, so that the valve body 10a is excited and the relief port 9 is opened. When the relief port 9 is opened, the fuel in the pump chamber 5 is relieved into the fuel tank via the overflow vibe 27, so that the fuel pressure in the pump chamber 5 decreases.

When the fuel pressure in the pump chamber 5 decreases, the timer 6
operates to the retard side L in response to a decrease in fuel pressure, and the roller ring 13 is rotated in the same direction as the drive shaft 11, so the holding position of each roller 13a changes, and the fuel injection timing is delayed, resulting in combustion. The pressure will drop.

Therefore, according to such a configuration, when the supercharging pressure of the intake air exceeds the set pressure, the boost compensator reduces the fuel injection amount (OLP operation), and at the same time the supercharging pressure sensor 8 and The solenoid valve 10, timer 6, etc. change the fuel injection timing from an injection timing commensurate with the engine speed to a retarded side, effectively reducing the combustion pressure of the fuel and quickly lowering the in-cylinder pressure to a safe state. can be done. As a result, the engine can be reliably protected from an abnormal supercharging pressure state when the waste gate valve or the like of the supercharger breaks down.

Moreover, with such a device, even if the boost compensator 7 is not operating normally, the boost pressure sensor 8, solenoid valve 10, timer 6, etc. can effectively lower the combustion pressure and reduce the in-cylinder pressure. Therefore, it is possible to protect the engine by effectively dealing with failures of waste gate valves, etc.

Although one embodiment of the present invention has been described below, it goes without saying that the present invention is not limited to the above embodiment.

For example, the boost pressure detection means inputs a pressure sensor to continuously detect boost pressure and a signal from this pressure sensor, and outputs a drive signal when the boost pressure exceeds the set pressure.・It may be constructed from a microcomputer unit, etc. Alternatively, the movement of the push rod of the boost convenor can be used as an ON/OFF switch, and when the boost pressure exceeds the set pressure, the push rod can be used to apply a drive signal to the actuator. good. Further, the actuator for opening and closing the relief port may be one that is operated by supercharging pressure, for example, one that includes a diaphragm or a valve body that opens and closes the relief port.

[Effects of the Invention] According to the present invention configured as described above, when the supercharging pressure of intake air exceeds the set pressure, the fuel injection amount is reduced and the fuel injection timing is adjusted to match the engine rotation. Since the timing is changed to the retarded side at a time appropriate for the speed, in the event of a failure of the supercharger's wastegate valve, etc., the cylinder pressure can be effectively and rapidly reduced to a safe state to reliably protect the engine. We can provide a distribution type fuel injection pump with excellent reliability.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is a vertical sectional view schematically showing a distribution type fuel injection pump, FIG. 2 is a schematic diagram of a feed pump and a timer, and FIG. 3 is a schematic diagram of a feed pump and a timer. 4 is a diagram illustrating the operation of main parts, and FIG. 4 is a timing chart diagram showing control setting conditions. FIG. 5 is a timing chart corresponding to FIG. 4 showing a conventional example. 2...Feed pump 3...Pump plunger 4...Spill ring 5...Pump chamber 6...Timer 7...Boost compensator 8...Supercharging pressure detection means (supercharging pressure sensor )9... Relief port 10... Actuator (solenoid valve)

Claims (1)

[Claims] A timer changes the fuel injection timing according to the fuel pressure in the pump chamber, and when the supercharging pressure of intake air exceeds the set pressure, the relative position of the pump plunger and spill ring is changed to reduce the fuel injection amount. The distribution type fuel injection pump is equipped with a boost compensator that causes the boost pressure to increase, and includes a boost pressure detection means that outputs a drive signal when the boost pressure of intake air exceeds a set pressure, and a boost pressure detection means that opens a relief port based on the drive signal. and an actuator for lowering the fuel pressure in the pump chamber.