JPH0614465U - Fuel injection pump - Google Patents

Abstract

(57) [Summary] [Purpose] By simply changing the existing plunger 7, the residual pressure at high speed rotation and high idling, such as high speed rotation and low load, can be maintained at a high level, and fuel injection timing can be advanced. To provide a fuel injection pump capable of stabilizing injection. [Structure] Focusing on partially forming a step on the inclined lead 18 formed on the peripheral surface of the plunger 7,
The spill side of the inclined lead 18 is characterized in that a partial step (stepped lead 19) is provided on the depth thereof, for example, on the low load side.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a fuel injection pump, and more particularly to a fuel injection pump in which the residual pressure in an injection pipe that pumps fuel is increased to advance the injection timing and at the same time stabilize the injection.

[0002]

[Prior art]

 In general, as a characteristic of the fuel injection pump, it is desirable to advance (advance) the fuel injection timing when the engine is rotating at high speed, and a timer (automatic advance device) for adjusting such injection timing is separately used. Instead, there is one that has a timing adjustment mechanism depending on the structure of the fuel injection pump itself. For example, there is Japanese Patent Publication No. 57-212364.

Further, in order to stably maintain the residual pressure in the injection pipe at the time of high speed rotation, a damping valve (not shown) is provided, or an Angreich cut (not shown) is provided, or the like. It is considered to be a delivery valve with a pressure valve (not shown).

As a configuration using a damping valve, a damping valve is provided on top of the delivery valve in addition to the delivery valve spring to make the fuel discharge slow.

However, the effect of such a damping valve is exerted in the entire engine rotation range, and there is a problem that the fuel discharge is deteriorated in both high load and low load in a particularly effective high speed rotation range.

Particularly, at high speed rotation and high load, there is a problem that the fuel injection period becomes long and smoke becomes worse.

Further, in the delivery valve with the Angreich cut, the residual pressure increases largely at low speed rotation and low load, and as shown in the timing map of FIG. 11, the rotation speed is lower than that at high speed and low load.・ There is a problem that the low load is more advanced.

Further, the equal pressure valve has a problem that the structure is complicated and the cost is high.

[0009]

[Problems to be solved by the device]

 The present invention has been made in consideration of the above problems, and by simply changing the existing plunger, the residual pressure during high speed rotation and low load such as high speed rotation and high idling can be maintained at a high level, and the fuel consumption can be kept high. An object of the present invention is to provide a fuel injection pump capable of advancing the injection timing and stabilizing the injection.

[0010]

[Means for Solving the Problems]

 That is, the present invention focuses on forming a stepped portion partially on the inclined lead formed on the peripheral surface of the plunger, and it is attached to the pump housing and the pump housing, and sucks and discharges the fuel communicating with the fuel storage chamber. It has a plunger barrel having a hole, and a plunger having a slanted lead formed at a position capable of reciprocatingly slidingly and rotatably inserted into the plunger barrel and communicating with the suction / discharge hole. A fuel injection pump for forming a fuel pressure chamber between the fuel injection chamber and the plunger barrel, and sucking fuel into the fuel pressure chamber from the fuel reservoir chamber by reciprocating sliding movement of the plunger. The spill side of the fuel injection po It is a flop.

[0011]

[Action]

 In the fuel injection pump according to the present invention, since the spill side of the inclined lead is provided with a partial step in the depth, the fuel is pumped as the plunger rises, and the inclined lead has a fuel inlet / outlet hole of the plunger barrel. When is engaged, the fuel spill does not suddenly occur, and the residual pressure can be maintained high and stable, so that the timing of fuel injection in the next cycle due to the rise of the plunger can be advanced. .

Therefore, for example, the fuel injection period can be extended in the low load region, and noise and nitrogen oxide reduction can be expected.

That is,

[0014]

【Example】

 Next, a fuel injection pump 1 according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a vertical cross-sectional view of the fuel injection pump 1, and FIG. 2 is a vertical cross-sectional view of a main part. The fuel injection pump 1 includes a pump housing 2 and a cam shaft 3 connected to an engine (not shown). It has a cam 4 attached to the above, an injection amount control rack 5, a plunger barrel 6, a plunger 7, a delivery valve 8, and a delivery valve holder 9.

The cam 4 is driven by the engine via the cam shaft 3, and reciprocates the plunger 7 in the vertical direction via the tappet roller 10.

The control rack 5 moves in a direction perpendicular to the paper surface to rotate the plunger 7 through a control sleeve 11 for the injection amount by a predetermined angle with its axis as a rotation axis.

The plunger barrel 6 is fixed in the fuel injection pump 1 and attached thereto, and the plunger 7 is housed therein so as to be reciprocally movable and rotatable. A fuel pressure chamber 13 is formed between the chamber 12 and the delivery valve 8.

A fuel intake / exhaust hole 14 is formed in the plunger barrel 6.

The plunger 7 reciprocates in the plunger barrel 6 to suck the fuel from the fuel storage chamber 12, compress the fuel in the fuel pressure chamber 13, open the delivery valve 8, and through the injection pipe 15 (FIG. 1). Fuel is pumped to a fuel injection nozzle (not shown).

A longitudinal fuel passage 16 communicating with the fuel pressure chamber 13 and a partial two-stage inclined lead 17 communicating with the vertical fuel passage 16 are formed on the peripheral surface of the head of the plunger 7. .

FIG. 3 is a sectional view taken along the line III-III in FIG. 2. As shown in the drawing, the depth of the partial two-step inclined lead 17 is not uniform, and a partial step is formed in a part thereof. This is the case.

That is, the partial two-step tilted lead 17 includes a tilted lead 18 having a uniform depth in the past and a spill side (upper end in the figure) on the low load side (left side in the figure) of the tilted lead 18. Only the edge side) is formed in the shallower step lead 19.

The depth D2 of the step lead 19, its range or length L, and width W are selected according to the depth D1 of the inclined lead 18, the desired residual pressure or the amount of advance angle. It shall be.

In the fuel injection pump 1 having such a configuration, the fuel in the fuel storage chamber 12 is sucked into the fuel pressure chamber 13 through the suction / discharge hole 14 as the plunger 7 descends.

As the plunger 7 rises, the upper end edge 7 A of the plunger 7 starts the compression of fuel from the time when the intake / exhaust hole 14 is closed, and the intake / exhaust hole 14 engages with the partial two-step inclined lead 17. To finish the fuel pumping.

That is, the stroke from the bottom dead center of the plunger 7 to the start of pressure feeding of the fuel is the prestroke, and the stroke from the closing and opening of the intake / exhaust hole 14 is the effective stroke.

Especially at the time of high speed rotation / low load, as the plunger 7 rises, the intake / exhaust hole 14 first communicates with the relatively shallow step lead 19, so that the spill speed of fuel from the injection pipe 15 side is small, and suddenly increases. It is possible to stabilize the residual pressure without lowering it, and it is possible to obtain a larger advance angle at high-speed rotation and low load and to stabilize the injection.

The residual pressure can be controlled by selecting the load area by selecting the formation area (length L) of the step lead 19 or the like.

Therefore, it is possible to delay the idling timing, reduce the idling sound and the nitrogen oxides, prevent the misfire and the blue and white smoke during the cold and high idling, and further extend the injection period in the low load range to reduce the noise. Effective in reducing nitrogen oxides.

FIG. 4 is a side elevational view of the essential part of the second embodiment of the present invention, and FIG. 5 is a sectional view taken along the line VV of FIG. This is composed of a triangular step lead 21.

According to this partial two-step inclined lead 20, the width of the step lead changes according to the change of the load range, so that the residual pressure can be controlled according to the load range.

FIG. 6 is a side elevational view of a main part of a third embodiment of the present invention, and FIG. 7 is a sectional view taken along the line VII-VI I of FIG. This is composed of a triangular and tapered step lead 31.

According to the partial two-stage inclined lead 30, the spill of fuel is gradually started by the engagement with the intake / exhaust hole 14, and the change in the residual pressure can be moderated.

FIG. 8 is a side elevational view of the essential portion of the fourth embodiment of the present invention, FIG. 9 is a sectional view taken along line IX-IX of FIG. 8, and FIG. 10 is a sectional view taken along line XX of FIG. The partial three-step tilted lead 40 includes two steps of a first step lead 41 and a second step lead 42 which are continuous in the circumferential direction of the plunger 7, and the first step lead 41 and the second step. This is constituted by a third stepped lead 43 which extends over the partial lead 42 and is formed deeper below them.

According to the partial three-stage inclined lead 40, the residual pressure can be controlled not only on the low load side but also on the high load side (the right side in the drawing).

[0037]

[Effect of device]

 As described above, according to the present invention, a partial step portion is formed on the conventional inclined lead, so that the residual pressure is stably maintained, and the injection timing is advanced, especially on the high speed / low load side. Stable injection characteristics can be obtained.

[0038]

[Brief description of drawings]

FIG. 1 is a fuel injection pump 1 according to a first embodiment of the present invention.
FIG.

FIG. 2 is a side elevational view showing a peripheral surface of a plunger 7 in which a partial two-stage inclined lead 17 is formed.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a side development view of the essential parts of a second embodiment of the present invention.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a side development view of the essential parts of a third embodiment of the present invention.

7 is a sectional view taken along line VII-VII in FIG.

FIG. 8 is a side elevational view of the essential parts of the fourth embodiment of the present invention.

9 is a sectional view taken along line IX-IX in FIG.

10 is a cross-sectional view taken along line XX of FIG.

FIG. 11 is a timing map shown in an NQ characteristic diagram of a conventional delivery valve with an Angleich cut.

[Explanation of symbols]

 1 Fuel Injection Pump 2 Pump Housing 3 Cam Shaft 4 Cam 5 Injection Volume Control Rack 6 Plunger Barrel 7 Plunger 7A Top Edge of Plunger 7 Delivery Valve 9 Delivery Valve Holder 10 Tappet Roller 11 Injection Volume Control Sleeve 12 Fuel Pool 13 Fuel pressure chamber 14 Fuel intake / exhaust hole 15 Injection pipe 16 Longitudinal fuel passage 17 Partial two-step inclined lead 18 Inclination lead 19 Shallow step lead 20 Part two-step inclined lead 21 Triangular step lead 30 Part two-step inclined lead 31 Triangular and Tapered Stepped Lead 40 Partial Three-Step Inclined Lead 41 First Stepped Lead 42 Second Stepped Lead 43 Third Stepped Lead D1 Depth of Inclined Lead 18 D2 Stepped Lead 19 Depth L Range of lead 19 (length) W Step Width of over de 19

Claims (1)

[Scope of utility model registration request] 1. A pump housing, a plunger barrel attached to the pump housing and having a fuel intake / exhaust hole communicating with the fuel storage chamber, and reciprocally slidably and rotatably inserted into the plunger barrel. A fuel pressure chamber is formed between the plunger and the plunger barrel, and a reciprocating sliding movement of the plunger causes the fuel pool to move. A fuel injection pump for sucking fuel into the fuel pressure chamber from the chamber and sending the fuel under pressure, wherein a partial step is provided in the depth on the spill side of the inclined lead.