JPS58222969A - Fuel-injection control system for internal-combustion engine - Google Patents

Abstract

PURPOSE:To aim at improving the extent of responsiveness in fuel injection control, by driving a control valve installed in a drain passage connected to a fuel-injection pump room, with a control pump. CONSTITUTION:A fuel-injection control system is provided with a fuel injection cylinder 10a, a fuel injection plunger 14, a fuel injection nozzle 36, a control valve 27 and a control pump 6. Fuel pressure inside a fuel-injection pump room 15 is intensified by the fuel injection plunger 14 while the control valve 27 is operated by the fed pressure of the control pump 6 and a drain passage is shut off and/or interconnected. Thus, the injection timing and quantity of fuel are controlled. Doing like this, such a fuel injection control system as being excellent in strength and responsiveness, besides small in size can be secured without using a high-performance solenoid valve.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for an internal combustion engine, particularly a unit injector system for a diesel engine.

In conventional unit injectors, the injection amount and injection period were controlled by a solenoid valve that directly received the injection pressure, so the solenoid valves used in this system had to meet very strict requirements regarding their response, strength, and electromagnetic force. was required.

The purpose of the present invention is to provide a fuel injection control system that is compact and has excellent strength and responsiveness without using solenoid valves of high performance. The above object is achieved by controlling with a control valve driven by discharge pressure.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Figure 1 shows the entire flow path system in a fuel injection system, where 1 is a fuel injection unit, 2 is an engine head, 5 is a fuel source, and 6 is a control pump. 6, a normal distribution type fuel injection pump is used. Further, the injection unit 1 is inserted into the engine head 2 via an O-ring 3.

The fuel injection unit 1 is shown enlarged in FIG. 2, where 8 is a spacer, 1o is a fuel injection cylinder, and 11 is a spacer.
indicates a control cylinder, and 12 indicates a nozzle holder. These control cylinder member 11 and nozzle holder 12 are integrally attached to the fuel injection cylinder member 1o by a holder nut 13.

Fuel injection cylinder 10a in fuel injection cylinder member 1o
A fuel injection plunger 14 is slidably inserted into the cylinder 10a, and a pump chamber 15 is formed within the cylinder 10a. The fuel injection plunger 14 is engaged with a follower 16, and the follower 16 is pushed downward (not shown) by a cam synchronized with the rotation of the engine, and upward by a follower spring 17 (3). Being pushed up. The fuel injection plunger 14 is equipped with a metering lead 19 that opens and closes the supply hole 18 formed in the cylinder 10a, and a spill lead 21 that opens and closes the relief hole 20.
A vertical hole 23a and a horizontal hole 23b are formed to communicate with each other.

The supply hole 18 and the relief hole 20 are communicated with a drain hole 110 of the control pump 6. Fuel from the feed pump 80 and the supply pump 50 is fed into the fuel chamber 113 of the housing 7 of the control pump 6, and excess fuel exits from the drain hole 110.

The pump chamber 15 is a metering boat 24 inside the spacer 8,
It communicates with the control cylinder lla in the control cylinder member 11 via the metering passage 25. Control cylinder 1
A control valve 27 is slidably mounted inside Oa, and this control valve 27 is always pushed upward by a spring 28.

An annular groove 29 is formed in the control valve 27, and this cD1
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(4) to mutually communicate and cut off the baud) 30. The drain boat 3o communicates with a fuel gear rally 4b in the holder nut 13 and a discharge hole 9, and is connected to a fuel reservoir 52 via a fuel gear rally 4a in the engine head 2 and a discharge passage 51, and further via an orifice 55 and a check valve 56.
It leads to

The metering boat 24 communicates with an injection nozzle 36 via a pressure passage 35 . The injection nozzle 36 is attached to the nozzle holder 12 via a beam tening nut 45, and the injection nozzle 36 is connected to a needle valve 37 (not shown in detail).
The needle valve 37 is press-biased by a nozzle spring 39 housed in a nozzle spring chamber 38. Note that the nozzle spring chamber 38 is communicated with the fuel gear rally 4b via a leak passage 40.31. A hydraulically actuated boat 41 is formed in the spacer 8 and opens to the control cylinder lla, and this hydraulically actuated boat 41 communicates with a control passage 42 . When hydraulic pressure higher than a predetermined pressure is applied to the oil-operated boat 41 through the control passage 42, the control valve 27 is activated by the spring 2.
8), the annular groove 29 is moved downward against the metering passage 2.
5 and the drain boat 30.

Note that 43 and 44 each indicate shims, which are used to adjust the stroke of the control valve 27 and the set pressure of the spring 28.

The control passage 42 is connected to the control pump 6 shown in FIG.
is communicated with. The control pump 6 in this embodiment is a distribution type pump, and 60 is a distribution cylinder;
1 is a distribution plunger, and these distribution cylinder 60 and distribution plunger 61 constitute a distribution pump chamber 62.

The distributor plunger 61 is integrally equipped with a face cam 63, and the distributor plunger 61 and the cam plate 112 with the face cam 63 are rotated by the engine. The face cam 63 has a number of cam surfaces corresponding to the number of cylinders and is in contact with the cam roller 64. cam roller 64
is rotatably attached to a roller poldani 65, and this roller holder 65 can rotate around the plunger 61. A timer lever 66 is connected to the row (6) holder 65, and the timer lever 66 is connected to a timer piston 67. A timer piston 67 is slidably inserted into the housing 7 of the control pump, and the timer piston 67 is biased in one direction by a spring 69. A space surrounded by the timer piston 67 and the housing 7 constitutes a working chamber 70, and this working chamber 70 communicates with the fuel chamber 113 via a timer orifice 71. In addition, in Fig. 1, the timer piston 6
7 is actually rotated 90 degrees from the illustrated state, and the axis of the timer piston 67 is arranged perpendicular to the plane of the paper, but for convenience of drawing, the illustrated posture is It is a picture. Therefore, timer piston 6
When the roller 7 is displaced in the axial direction, the roller holder 65 is rotated via the timer lever 66, so that the roller 64 is advanced.

A foot boat 73 is formed in the distribution plunger 61, and a communication passage 74 and discharge boats (7) 75a, 75b are also formed therein. An introduction boat 76 and an output boat 77 are formed in the distribution sill 60. The outlet boat 77 communicates with the control passage 42 . The introduction boat 76 is connected to a fuel supply pump 80 via a passage 78 and a fuel chamber 113. pump 8
0 is driven by the cam shaft 68 at the same time as the cam plate 112, etc., but a 90° expanded drawing is also shown for explaining the structure. The fuel pressure in the fuel chamber 113 is set to a predetermined pressure by the pressure regulating valve 81, and this pressure is applied to the working chamber 70 through the timer orifice 71 to determine the position of the timer piston 67 in balance with the spring 69.

Further, the discharge boat 75b of the distribution plunger 61 is connected to the spill ring 8 when the distribution plunger 61 is in a predetermined position.
It communicates with the fuel chamber 113 via the ring end surface 86 of No. 5.

Next, the operation will be explained.

The fuel whose maximum pressure has been adjusted is supplied from the fuel supply pump 80 to the cylinder via the fuel chamber 113 and the supply passage 54.
11'(8) is introduced into the fuel injection pump chamber 15 of the engine 10a. When the fuel injection plunger 14 is pushed down from the top dead center position by a cam (not shown), the fuel in the pump chamber 15 is pressurized. When the control valve 27 is pushed by the spring 28 and is at the top dead center, the metering passage 2 is opened through the annular groove 29.
5 and a drain boat 30 are in communication with each other, so that the fuel pressurized in the fuel injection pump chamber 15 is transferred to the fuel gear gallery via the metering boat 24, the metering passage 25, the annular groove 29, and the drain boat 130. 4b escapes.

When the timing lead 19 of the fuel injection plunger 14 closes the supply hole 18, the fuel in the pump chamber 15 is also discharged to the fuel gears 4b and 4a through the above-mentioned path, and flows into the fuel reservoir 52 via the orifice 55 and check valve 56. be returned.

At this time, the fuel supplied from the fuel supply pump 80 is controlled by the pressure regulating valve 81, and the oil pressure in the fuel chamber 113 and further in the working chamber 70 of the timer cylinder is controlled. Then, the timer piston 67 is displaced to a position balanced with the spring 69 (9), and the roller holder 65 is rotated via the timer lever 66, so that the cam roller 64 is advanced (or retarded).

Therefore, the position where the cam surface of the face cam 63 rides on the roller 64 changes, and the distribution plunger 61 is in the state shown in the figure.
That is, the closed position of the introduction boat 76 and the feed boat 73 is angularly displaced from the state where they are in communication. After the introduction boat 76 and the feed boat 73 are closed, the distribution plunger 61 is moved to the right in the figure, and the oil pressure in the distribution pump chamber 62 is increased. This high pressure fuel is supplied to the communication passage 74 and the control passage 4.
2 to the hydraulically operated boat 41. That is, since the pressure in the hydraulic boat 41 increases, the control valve 27 is lowered against the spring 28. Therefore, control valve 2
The annular groove 29 at No. 7 blocks communication between the metering passage 25 and the drain boat 30. When the control valve 27 is further lowered, the in-lead 32 opens the drain passage 26 to prevent the pressure in the operating boat 41 from becoming too high.

When the pressure decreases, high pressure fuel (10
) (The fuel discharge pressure of the supply pump 50 is set to a lower pressure than that of the pump 8o.) The fuel that pushes the check valve 83 open is supplied to the distribution pump chamber 62, and then passes through the communication passage 74 and the control passage 42 to the hydraulic pressure. It is supplied to the operating boat 41 and keeps the internal pressure of the boat 41 constant. When the control valve 27 shuts off the metering passage 25 and the drain boat 30, the fuel injection pump chamber 15
The pressurized fuel inside the engine cylinder can no longer escape, and this high-pressure fuel is sent to the fuel injection nozzle 36 through the pressure passage 35, pushes open the needle valve 37 built into the fuel injection nozzle 36, and enters the combustion chamber V of the engine cylinder. Inject fuel inside.

The fuel injection plunger 14 is subsequently lowered, but at the same time the distribution plunger 61 in the distribution pump 6 is further moved to the right by the face cam 63, so that the end surface 86 of the spill ring 85 communicates with the discharge boat 7jb.
Therefore, the fuel pressure in the distribution pump chamber 62 decreases, and the oil pressure in the hydraulically actuating boat 41 also decreases to the end surface 8 of the spill ring 85 via the control passage 42, the outlet boat 77, and the discharge hole 75a.
He is let go to 6. Therefore, the pressure in the hydraulic boat 41 decreases, and the control valve 27 is pushed up by the spring 28. Therefore, the annular groove 29 communicates the metering passage 25 with the drain boat 30, so that the high-pressure fuel in the pump chamber 15 is released to the fuel reservoir 52.

As a result, the pressure in the pressure feeding passage 35 also decreases, so fuel injection from the injection nozzle 36 is stopped.

Further, when the fuel injection plunger 14 descends, the spill lead 21 opens the relief hole 20, so that the fuel in the pump chamber 15 is also released from the relief hole 20 through the vertical hole 23a, the horizontal hole 23b, and the annular groove 22. Then, the fuel injection plunger 14 reaches the bottom dead center and is stopped. Note that the spill lead 21 is provided at a position where maximum injection can be ensured.

When the cam is rotated and the plunger 14 moves to the upward stroke, and the metering lead 19 opens the supply hole 18, the fuel chamber 113
From there, fuel is sent into the pump chamber 15 in preparation for the next descent of the fuel injection plunger 14. In this way, the next operation is performed again.

Note that the drain passage 26 has a sufficiently small diameter so that the fuel pressure in the operating boat 41 does not drop suddenly.

Therefore, in the above embodiment, the fuel injection timing is determined by the drive timing of the control valve 27, and the fuel injection amount is determined by the time during which the control valve 27 is moved. Since the control valve 27 is driven by the control pump 6, the injection timing and injection time can be determined by controlling the control pump 6. To explain further, in the case of the distribution type pump, the fuel injection start timing is controlled by the timing when the feed boat 73 and the introduction boat 76 close.
Further, the injection amount is determined by the time from when the feed boat 73 and the introduction boat 76 are closed until the discharge boat 75b and the end surface 86 are electrically connected.

The position of the spill ring 85 is determined by an adjustment lever 111 via a link mechanism 114.

Lever 111 is linked to the accelerator. Therefore, the position of the end face 86 of the spill ring 85 is controlled by the accelerator. In the control pump 6, the distribution (13) plunger 61 and face cam 63 rotate and reciprocate in response to the engine speed, so an injection amount can be obtained depending on the engine operating condition, and the pressure regulating valve 81 can be controlled. By doing so, the cam operation of the face cam 63 can be advanced or retarded by displacing the timer plunger 67, so that the injection timing can be controlled.

Moreover, the control valve 27 is housed in the control cylinder lla, and the annular groove 29 opens and closes the fuel flow, so the pressure resistance is high, and the return at the end of injection can be quickly performed, so injection can be cut with high precision.

Next, a second embodiment shown in FIG. 3 will be described.

The difference from the first embodiment is that the fuel supply passage 54 is connected not to the cylinder 10a but to the fuel gears 4a and 4b. According to this configuration, the fuel injection pump chamber 15
Fuel is supplied from the pump 80 through the fuel chamber 113, the supply passage 54, and the fuel passage 9.0 in the engine head 2 to the fuel (14) gears 4a, 4b. The course is supplied from the gear gallery 4b to the pump chamber 15 via the drain boat 30, the annular groove 29, the metering passage 25, and the metering boat 24, the passage 91 in the control cylinder member 11, and the passage 92 in the spacer 8. The pump chamber 15 is supplied from the pump chamber 15 through the supply hole 18 and the relief hole 20.
is supplied with fuel. According to this configuration, only one supply passage 54 is required for the multi-cylinder engine, and the cylinder 10a
It becomes easier to descend.

Note that the control pump 6 is not limited to the above-mentioned distribution type pump, and may also be implemented, for example, as a square type pump. Further, the fuel supply pump 80 can also serve as the supply pump 50. Furthermore, fuel gear 4a, 4
b does not need to be inside the engine head 2, and the same effect can be achieved by attaching something like a pipe to the top of the engine head.

As described in detail above, the present invention provides a control valve in the drain passage connected to the fuel injection pump chamber, and this control valve is driven by the control pump, so that the control pump is controlled according to the operating conditions of the engine. By driving the control valve, it is possible to obtain injection timing and injection amount that match the operating conditions of the engine. Furthermore, since the control valve is driven by the discharge pressure of the control pump 6, the high pressure in the pump chamber 15 does not act directly and does not require large pressure resistance, and the control valve operates in accordance with the pump pressure. Because of this, fuel cut-offs can be performed with high precision. Moreover, since the fuel circulates within the device during the non-injection period, a cooling effect can also be expected.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 show a first embodiment of the present invention.
The figure is an overall flow path system diagram in the fuel injection device according to the first embodiment of the present invention, and FIG. 2 is an enlarged configuration diagram of the fuel injection unit. FIG. 3 is an enlarged configuration diagram of a fuel injection unit according to a second embodiment of the present invention. 10a... Fuel injection cylinder, 14... Fuel injection plunger, 15... Fuel injection pump chamber, 36... Fuel injection nozzle, lla... Control cylinder, 27...
- Control valve, 6... control pump. Representative Patent Attorney Takashi Okabe (17)

Claims (1)

[Scope of Claims] A fuel injection cylinder (10a) connected to a fuel supply source, a fuel injection plunger (14) inserted into the fuel injection cylinder (10a) and driven by an engine, and a fuel injection plunger (14) that is driven by an engine. 14) and the fuel injection cylinder (
a fuel injection nozzle (36) communicating with the fuel injection pump chamber (15) formed by the fuel injection pump chamber (10a); and a control cylinder (36) formed in the middle of a drain passage communicating with the fuel injection pump chamber (15). control valve (
27) and a control pump (
6), the fuel pressure in the fuel injection pump chamber (15) is increased by the fuel injection plunger (14), and the control valve (27) is actuated by the supply pressure of the control pump (6>) to increase the fuel pressure in the fuel injection pump chamber (15). Fuel injection control system for an internal combustion engine (1), characterized in that fuel injection timing and fuel injection amount are controlled by blocking and communicating a drain passage.