JPH0421005Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dual plunger type fuel injection pump, and in particular to forced lubrication between two plungers.

A double plunger type fuel injection pump, that is, a first (main) plunger that sets the amount of fuel to be injected and forces the fuel to the injection valve for injection; In a fuel injection pump equipped with a second (auxiliary) plunger that adjusts the injection start timing, return of leaked fuel and forced lubrication are normally carried out between the inner circumferential surface of the plunger barrel that accommodates the first and second plungers and the outer surface of the plunger barrel. This is done only between the outer peripheral surface of the second plunger and the second plunger. The forced lubrication is performed to prevent leakage fuel from leaking into the cam chamber and to provide adequate lubrication.

However, in the conventional forced lubrication described above, that is, forced lubrication only between the inner circumferential surface of the plunger barrel and the outer circumferential surface of the outer second plunger, high-pressure fuel is used between the inner first plunger and the outer second plunger. leaked. This leaked fuel flows into the cam chamber and dilutes the lubricating oil, or mixes with the lubricating oil and sticks to various parts of the pump.

The present invention has been made in view of the above points, and includes forced lubrication between the outer circumferential surface of the first plunger and the inner circumferential surface of the second plunger, and collects the fuel leaking between these two plungers. The purpose is to prevent the plungers from flowing into the cam chamber and to provide appropriate lubrication between the two plungers. In order to achieve this purpose, the present invention includes a first plunger 3 for setting and pressure-feeding the amount of injected fuel, and a first plunger 3 that is integral with the first plunger 3 in the axial direction. a second plunger 4 which is movably and rotatably fitted in the circumferential direction and adjusts the injection start timing, and an annular leak fuel groove 3f and a first In the double plunger type fuel injection pump, in which a through hole 4c is formed respectively, and an annular leak fuel return groove 2c is formed in the plunger barrel 2 that accommodates the plungers 3 and 4 so as to be aligned with each other, the first plunger 3, an annular fuel/lubricating oil groove 3g is formed below the leak fuel groove 3f, and an annular lubricating oil groove 3h is formed below the fuel/lubricating oil groove 3g,
second and third through holes 4d and 4e are formed in the second plunger 4 at positions aligned with the fuel/lubricating oil groove 3g and the second lubricating oil groove 3h, respectively;
A fuel/lubricating oil return groove 2d and a lubricating oil supply groove 2e are formed on the inner circumferential surface of the plunger barrel 2 so as to be aligned with the fuel/lubricating oil groove 3g and the lubricating oil groove 3h, respectively, at a predetermined lift position. Within the wall of the plunger barrel 2, there is a fuel/lubricating oil return passage 2a communicating with the fuel/lubricating oil return groove 2d, and a lubricating oil supply communicating with the lubricating oil supply groove 2e and connected to the lubricating oil supply system. The present invention provides a double plunger type fuel injection pump characterized in that a passage 2b is formed.

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a longitudinal cross-sectional view of the essential parts of a double plunger type fuel injection pump to which the present invention is applied. A plunger barrel 2 is fitted inside the pump body 1, and a main plunger 3 and a main plunger 3 are fitted inside the plunger barrel 2. A sub-plunger 4 is fitted inside so as to be movable together in the axial direction and rotatable separately in the circumferential direction. The sub plunger 4 is fitted concentrically to the outside of the main plunger 3 and rotatably and movably in the axial direction between a head 3b in which an injection amount setting lead 3a is engraved and a lower step 3c. A timing setting lead 4a for adjusting the injection start timing is cut out at the upper end.

The timing control sleeve 5 is rotatably fitted to the lower part of the plunger barrel 2, and a pinion 5a carved on the outer peripheral surface of the upper end engages with a timing rack 6, and is inserted into a slit 5b provided along the axial direction in the lower part. The flange 4b of the sub-plunger 4 is fitted into the flange 4b.

The injection amount control sleeve 7 is rotatably fitted onto the timing control sleeve 5, a pinion 7a carved on the outer peripheral surface of the upper end engages with the injection amount control rack 8, and a slit provided along the axial direction on the lower part engages with the injection amount control rack 8. Main plunger 3 is inside 7b.
The collar portion 3d is inserted.

A seat 9 is fitted into the lower open end of the pump body 1, and is prevented from coming off by a snap spring 10, and the tip surface 3e of the main plunger 3 is in contact with the inner end surface. A plunger spring 1 is provided between the outer side of the control sleeve 7 and the step between the pinion 7a and the seat 9 via spring seats 11 and 12.
3 are interposed concentrically.

An annular leak fuel groove 3f, a fuel/lubricating oil groove 3g, and a lubricating oil groove 3h are provided at predetermined locations on the outer peripheral surface of the main plunger 3, and the sub plunger 4 is provided with an annular leak fuel groove 3f, a fuel/lubricating oil groove 3g, and a lubricating oil groove 3h, which are aligned with each of these oil grooves 3f, 3g, and 3h. A plurality of first through third through holes 4c, 4d, and 4e, for example, two each, are bored at the positions shown in FIG.

A fuel/lubricating oil return passage 2a and a lubricating oil supply passage 2b are bored in the wall of the plunger barrel 2 along the axial direction and at positions shifted by 180 degrees from each other.
The lower ends of each of these passages 2a, 2b are respectively closed by blind plugs, and the upper ends thereof are opened on the outer circumferential surface of the plunger barrel 2, respectively, and are connected to fuel/lubricant oil return side connection holes 1a drilled in the pump body 1. , are communicated with the lubricating oil supply connection hole 1b.

Grooves 2c, 2d, and 2e along the circumferential direction are provided at predetermined positions on the inner peripheral surface of this plunger barrel 2,
As shown in FIG. 2, the grooves 2d and 2e are provided 180 degrees apart and eccentrically, and the groove 2d is provided in the passage 2a.
The groove 2e communicates with the passage 2d. The groove 2c is formed in the same shape as the groove 2e on the same side,
The plunger barrel 2 is communicated with the fuel reservoir 14 via a leak fuel return passage 2f formed in the plunger barrel 2. The groove 2c is a leak fuel return groove, and the groove 2d is a fuel return groove.
The lubricating oil return groove and groove 2e are lubricating oil supply grooves. When the main plunger 3 is at a predetermined lift position, for example, the bottom dead center position, these grooves 2c, 2d, and 2e are inserted into the respective holes 4 of the sub-plunger 4, as shown in FIG.
The respective positions are set to match with c, 4d, and 4e.

The fuel/lubricating oil return side connection hole 1a is connected to, for example, a drain oil tank (both not shown) via a pipe line,
The lubricating oil supply connection hole 1b is connected to a lubricating oil supply system via a pipe (not shown), and pressurized lubricating oil is supplied thereto.

The operation of the above fuel injection pump will be explained below.

The main plunger 3 is the injection amount control rack 8
is rotated via the control sleeve 7, and the pump chamber 1 is rotated by the injection amount setting lead 3a of the head 3b and the overflow port 2h of the plunger barrel 2.
The amount of fuel to be injected in the pump chamber 15 is set by a cam (not shown) through the seat 9 against the plunger spring 13, and the fuel in the pump chamber 15 is compressed. Not to be pumped to the injection valve. On the other hand, the sub plunger 4 is rotated by the timing rack 6 via the control sleeve 5, and the timing setting lead 4a provided on the head and the timing port 2i of the plunger barrel 2 allow the main plunger 3 to pump the fuel in the pump chamber 15. Adjust the compression start time, that is, the injection start time.

As the main plunger 3 and the sub plunger 4 move up and down, fuel flows between the inner circumferential surface of the plunger barrel 2 and the outer circumferential surface of the sub plunger 4, and between the inner circumferential surface of the sub plunger 4 and the outer circumferential surface of the main plunger 3. leaked,
It flows downward, that is, toward the cam chamber. Main plunger 3
Most of the fuel leaked between the outer peripheral surface of the main plunger 3 and the inner peripheral surface of the sub-plunger 4 accumulates in the leak fuel groove 3f at the top of the main plunger 3, and the remaining small amount flows downward. The fuel accumulated in the leak fuel groove 3f flows out into the leak fuel return groove 2c of the plunger barrel 2 through the hole 4c of the sub-plunger 4.

Inner peripheral surface of plunger barrel 2 and sub-plunger 4
Most of the fuel leaked between the outer circumferential surface and the leak fuel return groove 2c accumulates in the leak fuel return groove 2c, and the remaining amount flows downward. The fuel accumulated in the groove 2c is returned to the fuel reservoir chamber 14 through the return passage 2f. That is, most of the leaked fuel is recovered and returned to the fuel reservoir chamber 14.

On the other hand, the pressurized lubricating oil supplied into the lubricating oil passage 2b of the plunger barrel 2 is supplied to the lubricating oil groove 3h at the lowermost part of the main plunger 3 through the lubricating oil supply groove 2e at the lowermost part and the hole 4e. It is also supplied between the inner peripheral surface of the barrel 2 and the outer peripheral surface of the sub-plunger 4.

Inner peripheral surface of plunger barrel 2 and sub-plunger 4
Most of the pressurized lubricating oil supplied between the outer circumferential surface of the cam flows downward and returns to the cam chamber while lubricating the circumferential surfaces of both, and a portion of the pressurized lubricating oil flows upward while lubricating the circumferential surfaces of both. As described above, the leak fuel flowing downward between these two circumferential surfaces is pushed up and collected in the fuel/lubricant oil return groove 2d of the plunger barrel 2 together with the leak fuel.

Most of the pressurized lubricating oil supplied into the lubricating oil groove 3h of the main plunger 3 flows downward into the cam chamber while lubricating the space between the outer peripheral surface of the main plunger 3 and the inner peripheral surface of the sub-plunger 4. A portion of the fuel returns and flows upward while lubricating the gap between the two, pushing up the leaked fuel flowing downward between the two as described above and collecting in the fuel/lubricating oil groove 3g. The mixed oil of leak fuel and lubricating oil accumulated in the oil groove 3g flows out into the return groove 2d of the plunger barrel 2 through the hole 4d of the sub-plunger 4.

Fuel/lubricating oil return groove 2d of plunger barrel 2
The mixed oil of leak fuel and lubricating oil accumulated inside is led to the above-mentioned drain oil tank through the passage 2a and the connection hole 1a.

In this way, most of the leaked fuel and lubricating oil are recovered, and only a small amount of the leaked fuel and lubricating oil are recovered as waste oil, and the leaked fuel does not flow into the cam chamber, so that the lubricating oil is It will not be diluted by leaked fuel.

As explained above, according to the present invention, the first plunger 3 sets the amount of injected fuel and pumps the fuel.
and a second plunger 4 which is fitted onto the first plunger 3 so as to be integrally movable in the axial direction with respect to the first plunger 3 and rotatable in the circumferential direction, and adjusts the injection start timing. provision, said first and second
An annular leak fuel groove 3f and a first through hole 4c are formed in the plungers 3 and 4, respectively, and an annular leak fuel return groove 2c is formed in the plunger barrel 2 that accommodates the plungers 3 and 4 so as to be aligned with each other. In the double plunger type fuel injection pump, an annular fuel/lubricating oil groove 3g is formed on the outer peripheral surface of the first plunger 3 below the leak fuel groove 3f.
An annular lubricating oil groove 3h is formed below the fuel and lubricating oil groove 3g, and second and third through holes 4d and 4e are formed in the second plunger 4 and the fuel and lubricating oil groove 3g and The fuel is formed at positions aligned with the second lubricating oil groove 3h, respectively, so that the fuel can be aligned with the fuel/lubricating oil groove 3g and the lubricating oil groove 3h, respectively, at a predetermined lift position on the inner circumferential surface of the plunger barrel 2. - A lubricating oil return groove 2d and a lubricating oil supply groove 2e are formed, and a fuel/lubricating oil return passage 2a communicating with the fuel/lubricating oil return groove 2d and the lubricating oil supply groove are formed in the wall of the plunger barrel 2. Connects to 2e,
and a lubricating oil supply passage 2 connected to the lubricating oil supply system.
b, so that sufficient lubrication is achieved between the first plunger 3 and the second plunger 4 and between the second plunger 4 and the plunger barrel 2, and the pressurized lubricating oil supplied to the lubricating oil groove 3h is Push up the fuel leaking between the outer peripheral surface of the first plunger 3 and the inner peripheral surface of the second plunger 4,
Since the leaked fuel flows out of the plunger through the second through hole 4d, etc., the leaked fuel is prevented from flowing into the cam chamber, and the lubricating oil is not diluted by the leaked fuel. Deterioration of the pump is prevented, and since fuel is not mixed into the lubricating oil, the fuel oil does not stick to each lubricating part of the pump, and the pump can always operate normally.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an embodiment of a double plunger type fuel injection pump to which the present invention is applied, and Fig. 2 is a sectional view perpendicular to the axial direction at the position of the groove 2d of the plunger barrel 2 shown in Fig. 1. It is. 1...Pump body, 2...Plunger barrel,
2a... Fuel/lubricating oil return passage, 2b... Lubricating oil supply groove, 2c... Fuel/lubricating oil return groove, 2d...
Fuel/lubricating oil return groove, 2e...lubricating oil supply groove, 3
...First (main) plunger, 3f...Leak fuel groove, 3g...Fuel/lubricating oil groove, 3h...Lubricating oil groove, 4...Second (sub) plunger, 4c, 4d,
4e...first, second, and third through holes.

Claims (1)

[Scope of utility model registration request] A first plunger 3 that sets and pressure-feeds the amount of fuel to be injected; and a first plunger 3 that is externally fitted to the first plunger 3 so as to be integrally movable in the axial direction and rotatable in the circumferential direction with respect to the first plunger 3. and a second plunger 4 for adjusting the injection start timing,
An annular leak fuel groove 3f and a first through hole 4c are formed in the second plungers 3 and 4, respectively, and an annular leak fuel return groove 2c can be aligned with each other in the plunger barrel 2 that accommodates the plungers 3 and 4. In the double plunger type fuel injection pump, the outer circumferential surface of the first plunger 3 includes:
An annular fuel/lubricating oil groove 3g is formed below the leak fuel groove 3f, and an annular lubricating oil groove 3h is formed below the fuel/lubricating oil groove 3g. The through holes 4d and 4e of No. 3 are connected to the fuel/lubricating oil groove 3g and the second lubricating oil groove 3h.
The fuel and fuel are formed on the inner circumferential surface of the plunger barrel 2 at a predetermined lift position.
A fuel/lubricating oil return groove 2d and a lubricating oil supply groove 2 are aligned with the lubricating oil groove 3g and the lubricating oil groove 3h, respectively.
e and within the wall of the plunger barrel 2,
A fuel/lubricating oil return passage 2a communicating with the fuel/lubricating oil return groove 2d and a lubricating oil supply passage 2b communicating with the lubricating oil supply groove 2e and connected to the lubricating oil supply system are formed. Features a double plunger type fuel injection pump.