JPS62288362A - Fuel injection system - Google Patents

Abstract

PURPOSE:To make it possible to independently control the feed rate of oil, by opening and closing a relief passage for a pump chamber with the use of a solenoid valve to control the timing of fuel injection, and by adjusting the rotation of a cam ring to control the feed rate of oil during initiation of pressure feed. CONSTITUTION:Plungers 20,... are reciprocated under action of a cam ring 23 when a rotor 2 is rotated in association with the rotation of an engine so that a plunger chamber 19 and a pump chamber 3 fall in pressurized and vacuum conditions so that fuel is sucked up from a fuel tank into a sucking passage 6 through a check valve in the vacuum condition while a relief passage 8 is closed to initiate fuel injection when a solenoid valve 9 is turned in the pressurizing condition. Further, when the solenoid valve 9 is turned off after a predetermined amount of fuel injected, the relief passage 8 is opened to complete the fuel injection. In this arrangement, if it is desired to delay the timing of fuel injection, when a cam ring 23 is rotated by means of a rotary lever 25, the plungers 20 may pushed by even a low cam rise section during initiation of pressure feed, and therefore, the feed rate of oil may be lowered. Thus, it is possible to obtain a fuel injection characteristic in accordance with the operating condition of the engine.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a device for controlling fuel pumping timing and oil pumping rate in a fuel injection pump.

[Conventional technology]

An inner cam type distribution type (CAV type) fuel injection pump rotatably accommodates a rotor in the pump housing, and rotates the rotor in response to the rotation of the engine.
A plunger is movably attached to each plunger chamber formed in the radial direction of the rotor, and the plunger communicates with the plunger chamber by reciprocating in the radial direction according to the shape of the cam crest formed on the inner surface of the cam ring. Fuel is sucked into the pump chamber, and the fuel in the pump chamber is pressurized and distributed under pressure to respective discharge passages leading to the engine.

In such an inner cam type distribution fuel injection pump, in order to control the fuel injection timing, that is, the pumping timing, it is conventionally known to use a solenoid valve to open and close a relief passage connected to the pump chamber. . This device increases the fuel pressure in the pump chamber by closing the relief passage with a solenoid valve when the fuel injection start timing comes, and supplies the fuel to the injection nozzle of each engine through the discharge passage and injects it. Furthermore, when the solenoid valve is used to open the relief passage, fuel in the pump chamber is released from the relief passage, thereby ending fuel injection.

[Problem that the invention seeks to solve]

In the conventional pumping timing adjustment device, for example, if the pumping timing is delayed, the timing to start pumping in the pump chamber is delayed, so the plunger starts pumping at a high point on the cam ridge formed on the inner surface of the cam ring. The fuel pumping speed increases, and the so-called oil feeding rate (fuel feeding amount/unit time) becomes high.

During idling, etc., there is a demand for delaying the injection timing and lowering the oil feed rate, but the conventional pumping timing adjustment device described above cannot meet such demands.

The present invention aims to provide an inner cam distribution type fuel injection pump that can independently control fuel pumping timing and oil feeding rate.

[Means for solving problems]

The present invention controls the start and end timing of fuel pumping by opening and closing a relief passage connected to a pump chamber using a solenoid valve, and also controls the timing of starting and ending fuel pumping by opening and closing a relief passage connected to a pump chamber. It is characterized in that the oil feeding rate at the start of pressure feeding is controlled.

[Effect]

According to the present invention, the fuel injection timing can be controlled by a solenoid valve as in the past, and the oil feed rate can be controlled by rotating the cam ring to change the timing at which the cam crest pushes the plunger. You will be able to do this.

[Embodiments of the invention]

The present invention will be described below based on an embodiment shown in the drawings.

In the figure, l denotes a pump housing in which the rotor 2 is rotatably and oil-tightly housed.

The rotor 2 is rotated according to the rotation of the engine,
A pump chamber 3 is configured between the tip of the rotor 2 and the pump housing 1. Fuel is introduced into the pump chamber 3 from a fuel tank 4 by a feed pump 5 through a suction passage 6, and this suction passage 6 is provided with a check valve 7.

A relief passage 8 is connected to the pump chamber 3, and a downstream end of the relief passage 8 is open to the fuel tank 4. A solenoid valve 9 is provided in the middle of the relief passage 8.

The solenoid valve 9 is a spool valve lO that opens and closes the relief passage 8.
and a solenoid 11 that operates the spool valve 10 in the axial direction.When the spool valve IO is moved to the left in FIG. The annular groove 12 blocks the relief passage 8.

There are springs 13° and 14 on both sides of the spool valve lO in the axial direction.
are provided, and these springs 13, 14 push against the spool valve 10. And one spring 1
3 is set to be slightly larger than the other spring 14, and when the solenoid 11 is not energized, the spool valve IO is pushed toward the right side in the figure, and the relief passage 8 is opened to the fuel tank 4 side through the annular groove 12. It looks like this.

The chamber 15 housing one of the springs 13 is connected to the pump chamber 3 through a communication passage IB, and a check valve 17 is provided in the communication passage IB. When the fuel pressure in the pump chamber 3 reaches a predetermined pressure or higher, the check valve 1
7 is opened and the fuel in the pump chamber 3 flows from the communication path 1B to the chamber 1.
5, thereby pushing the spool valve lO to the right in the figure and maintaining the relief passage 8 in an open state.

A vertical hole IB is formed on the central axis of the rotor 2, and one end of this vertical hole 18 is connected to the pump chamber 3, and the other end is connected to the plunger chamber 19 provided in the rotor 2.
I am familiar with...

The plunger chambers 19 are provided in a radial direction with respect to the rotor 2, and plungers 20 are fitted into these plunger chambers 19 so as to be slidable in the radial direction.

At the outer end of each plunger 20... there is a roller lash 21...
are in contact with each other, and cam rows 722 are rotatably held in these roller lashes 21.

The cam rollers 22 are configured to come into rolling contact with the inner surface of a cam ring 23 provided on the pump housing 1, and the cam ring 23 has a plurality of cams spaced apart in the circumferential direction on the inner surface, as shown in FIG. It is equipped with mountain 24...

When the rotor 2 rotates, the plungers 20 . . . , the roller units 21 . . . and the cam rollers 22 .
The cam rollers 22 . When the cam rollers 22... ride on the cam ridges 24... of the cam ring 23, the plungers 20... are pushed toward the center of the rotor 2, and the cam rollers 22... ride on the cam ridges 24... When the plungers 20 come into contact with the valleys between them, the plungers 20 move in the outer diameter direction of the rotor 2.

That is, the plungers 20... are reciprocated as the rotor 2 rotates, thereby causing the plunger chambers 19...
Make the interior pressurized and negative pressure.

For this reason, the pump chamber 3 communicating with the plunger chambers 19 through the vertical holes 18 becomes pressurized and under negative pressure, and performs a pumping action.

The cam ring 23 is attached to the pump housing 1 so as to be rotatable in the circumferential direction, and has a rotary lever 2 on its outer surface.
It is equipped with 5.

The rotating lever 25 is configured to be rotated in the circumferential direction by a drive device (not shown), and the cam ring 23 is also rotated in the circumferential direction as a result of this rotation.

A distribution passage 26 is formed in the rotor 2 midway in the axial direction, and this distribution passage 2G communicates with the vertical hole L8, and also has a distribution boat 2 opened on the outer surface of the rotor 2.
7.

Opposed to this distribution boat 27, the pump housing 1 is provided with a plurality of discharge passages 28 spaced apart in the circumferential direction, as shown in FIG. The port 27 is successively connected to and disconnected from one of the discharge passages 28 .

The discharge passages 28 are provided in correspondence with the number of combustion chambers of the engine, and each of these discharge passages 28 is connected to a fuel injection nozzle (not shown) provided in each combustion chamber.

The operation of the embodiment with such a configuration will be explained.

When the rotor 2 is rotated by the rotation of the engine, the plunger 20 is rotated by the action of the cam ring 23, as described above.
... is moved back and forth, which causes the plunger chamber 19...
・The pump chamber 3 is also brought into a pressurized and negative pressure state to perform a pumping action.

When the pump chamber 3 is in a negative pressure state, fuel is introduced from the fuel tank 4 through the suction passage 6. The introduced fuel does not flow back to the suction passage B side due to the action of the check valve 7.

When the pump chamber 3 is pressurized, the fuel in the pump chamber 3 is discharged from the relief passage 8 to the fuel tank 4 side.

However, when the pump chamber 3 is pressurized and the solenoid 11 of the electromagnetic valve 9 is energized, the spool valve 10 is moved to the left in FIG. As the water drips down, the relief passage 8 is blocked. Therefore, the fuel in the pump chamber 3 is pushed out through the vertical hole 18, the distribution passage 261, and the distribution port 27, into the discharge passage 28 communicating with the distribution port 27, and is injected from the fuel injection nozzle connected to this discharge passage 28. Ru.

When a predetermined amount of fuel is injected from each injection nozzle, power to the solenoid 11 is cut off.

Then, the spool valve lO is moved by the spring 13 and the part f.
Pushed by the fuel pressure of f115, it moves to the right in FIG. 1, and the annular groove 12 communicates with the relief passage 8'. As a result, the fuel in the pump chamber 3 is released from the escape passage 8 to the fuel tank 4, and the pressure in the pump chamber 3 is reduced, so that injection from the injection nozzle is terminated.

The fuel in the chamber 15 escapes to the escape passage 8 through the gap between the outer circumferential surface of the spool valve 10 and the inner surface of the valve chamber housing the spool valve IO, and the plungers 20... When the pump chamber 3 reaches the valley and becomes under negative pressure, the suction passage 6 opens again.
Fuel is introduced from the fuel tank 4 through the fuel tank 4.

Thereafter, by repeating such operations, fuel is distributed and supplied to each injection nozzle.

In the case of the above embodiment, the fuel in the pump chamber 3 is started to be pumped toward the injection nozzle by closing the relief passage 8, so the time when the electromagnetic valve 9 is energized is the time to start pumping. The time when the energization to the solenoid valve 9 is stopped is the end time of pressure feeding.

, Eka'v-Cs electromagnetic o9. ．． If it is controlled according to the t6 energization and engine operating conditions, it becomes possible to control the fuel injection timing.

For example, if the timing of energizing the solenoid 11 is delayed during idling, the timing of fuel injection will also be delayed.

By the way, if the fuel injection timing is delayed as described above, the plunger 20 will start pressurizing the fuel in the latter half of the rise of the cam ridges 24 on the cam ring 23, and the plunger 20 will pressurize the fuel. The speed becomes faster. In other words, the oil feed rate becomes high.

In contrast, in this embodiment, the cam ring 23 is attached to the pump housing l so as to be rotatable in the circumferential direction, and a rotary lever 25 is provided, and the rotary lever 25 is rotated in the circumferential direction by a drive device (not shown). Because I made it so that
When the above fuel injection timing is delayed, the cam ring 23
can be rotated so that the plunger 20 is pushed at a low point on the cam crest 24 at the start of pressure feeding. This makes it possible to lower the oil feed rate.

Therefore, by relatively advancing the fuel injection timing and lowering the oil feed rate, it becomes possible to satisfy the fuel injection characteristics required during idling operation.

In addition, in the case of the above embodiment, since the springs 13 and 14 are installed on both sides of the spool valve 10, the spool valve 10 does not swing in the axial direction due to vibration, and the electromagnetic force required for the solenoid 11 is reduced. This reduces the amount of time required and improves responsiveness.

Furthermore, since one chamber 15 housing the spring 13 is electrically connected to the pump chamber 3 via the communication path IB, if the spool valve 10 becomes unable to move smoothly due to getting caught in dust or seizing, etc. In this case, the spool valve 10 is forcibly pushed to the right in the drawing by the pressure of the fuel introduced into the chamber 15, and the relief passage 8 is maintained in an open state, thereby preventing the vehicle from overrunning.

〔Effect of the invention〕

As explained above, according to the present invention, the fuel pressure feeding timing can be controlled by opening and closing the relief passage connected to the pump chamber using a solenoid valve, and the oil feeding rate can be controlled by rotating the cam ring. By doing this, it is possible to control the timing by changing the timing when the cam mountain pushes the plunger, and therefore it is possible to control the fuel pressure feeding timing and the oil feeding rate independently of each other, so that they can be controlled according to the operating conditions of the engine. injection characteristics can be obtained.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a sectional view of an inner cam fuel injection pump, and FIGS. 2 and 3 are sectional views taken along the line ■-■ and the line ■-■ in FIG. 1, respectively. be. l...Pump housing, 2...Rotor, 3...
Pump chamber, 6... Suction passage, 8... Relief passage, 9.
...Solenoid valve, lO...Spool valve, 11...Solenoid, 18...Vertical hole, 19...Plunger chamber, 20
...Plunger, 21...Rorash, 22...
Cam roller, 23...Cam ring, 24...Cam mountain, 25...Rotating lever, 2B...Distribution passage, 27.
...Distribution boat, 28...Discharge passage.

Claims (1)

[Claims] A plurality of plungers are attached to a rotationally driven rotor so as to be freely movable in the radial direction, and these plungers reciprocate in the radial direction according to the shape of the cam ridge formed on the inner surface of the cam ring, thereby sucking fuel into the pump chamber and pumping the fuel into the pump chamber. In an inner cam type distribution type fuel injection pump that pressurizes the sucked fuel, the timing to start and end the pumping of fuel is controlled by opening and closing the relief passage connected to the pump chamber using a solenoid valve, and the cam ring is A fuel injection pump characterized in that the oil feeding rate at the time of starting the pressure feeding is controlled by rotationally adjusting the fuel injection pump in the circumferential direction.