JPS633415Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention enables fuel to be pumped by reciprocating the plunger within the plunger insertion hole formed in the pump body, and also enables fuel to be pumped into the fuel chamber formed at the middle position of the plunger insertion hole. The fuel injection valve is fitted on the outside of the plunger and rotated relative to the plunger to control the amount of fuel injected by changing the opening/closing timing of an oil hole communicating with the top of the plunger. The present invention relates to a fuel injection pump that houses an annular valve that controls fuel injection timing by being displaced in the axial direction of a plunger.

Conventional general fuel injection pumps have a hard steel barrel fitted into a pump body made of a relatively soft material such as cast iron, and pump fuel by reciprocating a plunger within the barrel. I have to.

However, in this conventional fuel injection pump, at the end of fuel injection, the high-pressure fuel pressurized by the plunger passes through the oil escape hole formed in the barrel side wall and becomes a shock wave in the fuel chamber formed inside the pump body. When the fuel injection pump is used for a long period of time, the shock waves of the spilled fuel cause cavitation corrosion on the wall surface of the fuel chamber, which is made of a relatively soft material. Therefore, in this type of fuel injection pump, a protector made of a hard material must be disposed inside the fuel chamber at a position where spilled fuel is injected at the end of fuel injection.
There was a problem that the number of parts increased and the mounting structure of the protector became complicated.

In view of the problems of conventional fuel injection pumps as described above, the present invention has a simple structure that does not require the installation of a protector on the inner side of the fuel chamber, and yet it protects the inner surface of the fuel chamber by spilled fuel at the end of fuel injection. The purpose of this invention is to provide a fuel injection pump that can prevent cavitation corrosion, and in order to achieve this purpose, a plunger insertion hole is formed directly in the pump body made of hard steel. Furthermore, a fuel chamber is formed at a middle position of the plunger insertion hole, and fuel can be pumped by reciprocating the plunger within the plunger insertion hole. By being rotated relative to the plunger, the opening/closing timing of an oil hole communicating with the top of the plunger is changed, thereby controlling the amount of fuel to be injected, and the plunger is also displaced in the axial direction. The fuel injection pump houses an annular valve which acts to control the injection timing of fuel by means of a fuel injection pump, and the fuel chamber is formed into a recessed hole extending inward from the outer circumferential surface of the pump body. the annular valve has a spill hole that communicates with the oil passage hole and spills the pressurized fuel in the plunger insertion hole in order to terminate fuel injection;
The fuel chamber is characterized in that the fuel chamber has an opening toward a position appropriately offset from the deepest part of the inner wall surface of the fuel chamber in the recess direction.

Hereinafter, the fuel injection pump of the present invention will be explained based on the illustrated embodiment.The fuel injection pump of the present invention shown in FIGS. A plunger insertion hole 2 is formed directly in the shaft center, and the plunger insertion hole 2 is
A plunger 3 is inserted therein so as to be vertically movable.

The pump body 1 is made of case-hardened steel (for example, SCM21) that undergoes heat treatment such as hardening after processing each part.
It is made of hard steel such as.

A fuel chamber 4 is formed at the axial interruption of the plunger insertion hole 2 . This fuel chamber 4 is formed into a concave hole shape by drilling so as to cross the plunger insertion hole 2 from the side surface of the pump body 1, and the fuel chamber 4 has an appropriate height in the axial direction and a concave hole shape in the radial direction. It has a peripheral wall surface 4a forming a rectangular cross-sectional space having a considerably larger diameter than the plunger insertion hole 2, and a back wall surface 4b formed into a conical inclined surface by the cutting edge of the drilling tool. ing. The opening of the fuel chamber 4 on the side surface of the pump body 1 is closed by a boss 60 for attaching a timer pin 6, which will be described later.

A fuel supply pipe 1 is connected to the fuel chamber 4 through a communication hole 14 formed diagonally upward in the pump body 1.
3 is connected.

In the upper part of the plunger 3, an oil passage hole 31 is bored in the center thereof, reaching an appropriate depth from the top 3a, and a suction hole 32 is provided at the lower end of the oil passage hole 31.
However, oblique groove-shaped leads 33 are formed slightly above the suction holes 32, respectively.

A control sleeve 7 is disposed at the bottom of the pump body 1, and the control sleeve 7
A collar 3 provided at the lower part of the plunger 3 in the groove 7a of the
6 is inserted. A lever 37 connected to a governor (not shown) is fixed to the control sleeve 7, and the plunger 3 can be rotated via the control sleeve 7 by the action of the governor in response to an increase or decrease in engine speed. It's becoming like that.

A fuel pressurizing chamber 10 is formed in the upper part of the plunger 3, and a discharge valve holder 11 housing a discharge valve 12 is provided above the fuel pressurizing chamber 10.

This plunger 3 is a plunger spring 3
5 toward the fuel cam 8 side.

An annular valve 5 is housed in the fuel chamber 4 so as to be fitted onto the outside of the plunger 3. This annular valve 5 has the function of changing the injection amount and timing of fuel by being rotated or moved up and down relative to the plunger 3, and has a polygonal base body with an appropriate height. 50. A plunger insertion hole 51 is formed through the center of the annular valve base 50 . A circular recess 52 for fitting an eccentric head 62 (described later) of the timer pin 6 is formed in one outer side 5a of the annular valve base 50. Moreover, the annular valve base 5
A small hole 53 that reaches the plunger insertion hole 51 is formed in the outer surface 5b opposite to the outer surface 5a on the forming side of the recess 52. This small hole 53 serves as a spill hole for fuel, and will hereinafter be referred to as spill hole 53. This spill hole 53 is opened toward the side wall of the fuel chamber 4.

This annular valve 5 is accommodated in the fuel chamber 4 before the plunger 3 is inserted into the plunger insertion hole 2,
Thereafter, the plunger 3 is inserted into the outside of the plunger 3 by passing it through the plunger insertion hole 2 from below the pump body 1 and through the plunger insertion hole 51 of the annular valve 5. Furthermore, when the annular valve 5 is fitted into the fuel chamber 4, the spill hole 53 is located above the deepest part of the inner wall surface 4b of the fuel chamber 4 (i.e., the center of the conical inner wall surface). It is opened toward the deviated position.

This annular valve 5 can be rotated and moved up and down relative to the plunger 3 by a timer pin 6.

The timer pin 6 has its pivot 61 which is the center of rotation.
A head 62 eccentric to the axis of the base shaft 61 is provided at the tip of the base shaft 61 . This timer pin 6
is attached to the side wall 1a of the pump body 1 by a timer pin attachment boss 60 with its eccentric head 62 fitted into a recess 52 formed on the outer surface 5a of the annular valve. The eccentric head 62 has an outer diameter D that is approximately the same as the inner diameter D' (FIG. 3) of the recess 52 on the outer surface 5a of the annular valve, and the eccentric head 62 can be fitted into the recess 52. This makes it possible to restrict rotation and vertical movement of the annular valve 5 with respect to the plunger 3. The timer pin 6 is rotatable within its mounting boss 60, and when the timer pin 6 is rotated, its eccentric head 62 is rotatable within the recess 52 of the annular valve outer surface 5a. It's summery.

A lever 63 for rotating the timer pin 6 is attached to the outer end of the timer pin 6. This timer pin rotation lever 63 is adapted to pivot in response to fluctuations in engine speed.

Further, in the fuel injection pump of the illustrated embodiment, when the engine is stopped, the timer pin rotation lever 63 faces directly laterally, and the timer pin eccentric head 6
2 is fitted into the recess 52 of the annular valve 5 at a lateral position on the opposite side of the timer pin rotation lever 63 with respect to the timer pin base shaft 61. When the engine speed increases, the timer pin rotation lever 63 is driven in the direction of arrow A. When the engine speed increases, the timer pin 6 is rotated by the lever 63, and its eccentric head is rotated by the lever 63. 62 is in the diagonal downward direction (arrow
A′ direction), and the annular valve 5 is displaced in the advance direction (downward) with respect to the plunger 3 as shown by arrow A″, and is also rotated in the direction to decrease the fuel injection amount. It's summery.

In addition, the reference numeral 9 in the figure indicates the fuel cam 8 and the plunger 3.
18 is a tappet roller, and 19 is a pump mounting flange formed on the outer side of the pump body 1.

Next, to explain the function and operation of the illustrated fuel injection pump, the fuel chamber 4 of this fuel injection pump
Fuel is pumped into the tank from a fuel supply device (not shown) such as a head tank or a feed pump.
The fuel introduced into the fuel chamber 4 flows through the suction hole 32 of the plunger 3 as the plunger 3 reciprocates.
The fuel is sucked into the pressurizing chamber 10 through the oil passage hole 31, is further pressurized by the plunger 3, and is then pressure-fed from the discharge valve 12 to the engine side. The amount of fuel injected under pressure to the engine side is determined by rotating the lever 37 and control sleeve 7 attached to the lower part of the pump body 1 by means of a governor that is displaced according to changes in the engine load. A lead 33 is rotated relative to the annular valve 5 and communicates with the plunger top 3a through the oil hole 31.
It is controlled by changing the interlocking timing between the fuel and the spill hole 53 of the annular valve 5, and thereby changing the release timing of the pressurized fuel.

On the other hand, the fuel injection timing is adjusted by appropriately rotating the timer pin 6 with a lever 63 that is changed according to fluctuations in engine speed, and the eccentric head 62 of the timer pin 6 is fitted. By appropriately displacing the annular valve 5 in the axial direction of the plunger 3,
The suction hole 3 communicates with the oil passage hole 31 of the plunger 3.
This is done by adjusting the timing to open and close the leads 2 and 33. In other words, when the engine rotates at high speed,
The timer pin rotation lever 63 is driven in the direction of arrow A to displace the annular valve 5 downward relative to the plunger 3, thereby acting to advance the fuel injection timing.

When the engine is rotating at high speed, the timer pin 6 is rotated in the advance direction, and the timer pin eccentric head 62 is slightly displaced in the direction of arrow A', causing the annular valve 5 to slightly inject fuel to the plunger 3. It is relatively rotated in the direction of decreasing amount. This means that when the engine rotates at high speed, one of the plungers 3
This is to correct the characteristic that the amount of fuel injection per stroke increases (dynamic fuel injection characteristic).

When the engine speed decreases, the timer pin rotation lever 63 is driven in the direction of arrow B, contrary to when the engine is rotating at high speed, and accordingly, the timer pin eccentric head 62 is moved in the direction of arrow B' (upward diagonal direction). Also, annular valve 5
is in the direction of arrow B″ (retard angle and fuel injection amount reduction direction)
driven by

Note that at the end of fuel injection, that is, plunger 3
When the reed 33 of the annular valve 5 and the spill 53 of the annular valve 5 communicate with each other, the fuel pressurized by the plunger 3 suddenly jets out from the spill hole 53 into the fuel chamber 4. As mentioned above, if the spilled fuel ejected into the fuel chamber 4 becomes a shock wave and collides with the wall surface of the fuel chamber, the wall surface may be eroded. It was common to provide a protector on the inner surface of the 4. However, providing a protector in this way increases the number of parts and complicates the structure, which is not a good idea.For this reason, in this embodiment, the selection of the material and shape of the fuel chamber 4 itself, as well as the selection of the fuel Chamber 4 and annular valve 5
By appropriately setting the relative relationship between the fuel chamber 4 and the spill hole 53, erosion of the inner wall surface of the fuel chamber 4 caused by the impact force of spilled fuel can be effectively prevented without providing a protector. That is, first,
The pump main body 1 in which the fuel chamber 4 is directly formed is made of hard steel with excellent corrosion resistance, and the inner wall surface of the fuel chamber 4 (i.e., the peripheral wall surface 4a and the inner wall surface 4b) is made of a corrosion-resistant wall surface to improve its corrosion resistance. It is planned.

In addition, when the annular valve 5 is fitted into the fuel chamber 4 of the pump body 1, the spill hole 53 of the annular valve 5
The relative positional relationship between the annular valve 5 and the pump body 1 is set such that the annular valve 5 is opened toward the inner wall surface 4b of the fuel chamber 4. Therefore, the impact force caused by the spilled fuel spouted from the spill hole 53 at the end of fuel injection is applied in a direction perpendicular to the rear wall surface 4b by colliding with the rear wall surface 4b which is an inclined surface. It is dispersed in two directions parallel to , and the erosion effect on the inner wall surface 4b is reduced to that extent.

Further, the spill hole 53 of the annular valve 5 is opened toward the back wall surface 4b of the fuel chamber 4 as described above.
The position facing the rear wall surface 4b is deviated upward from the center of the rear wall surface, which is the deepest part of the rear wall surface 4b. Therefore, after the spilled fuel ejected from the spill hole 53 collides with the back wall surface 4b, it flows in a direction away from the spill hole 53 along the back wall surface 4b, and the impact force of the ejected fuel is attenuated accordingly. , the influence of the impact force on the erosion of the back wall surface 4b is reduced.

These three means make it possible to prevent the inner wall surface of the fuel chamber 4 from being eroded as much as possible due to the impact force of spilled fuel without providing a protector.

As is clear from the above description, the fuel injection pump of the present invention is characterized by the selection of the material of the pump body in which the fuel chamber is recessed, the shape of the fuel chamber, and the annular valve housed in the fuel chamber and the fuel chamber. By appropriately setting the relative positions of the fuel chamber and the spill hole, the inner wall surface of the fuel chamber can be easily eroded by the spilled fuel spouted from the spill hole, even though the structure is simple and does not require a protector inside the fuel chamber. This has the practical effect of preventing such occurrences as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a fuel injection pump according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of FIG.
3 is an exploded perspective view of the plunger, annular valve, and timer pin portions of the fuel injection pump of FIG. 1. FIG. 1...Pump body, 2...Plunger insertion hole,
3...Plunger, 3a...Plunger top, 4
... Fuel chamber, 5 ... Annular valve, 6 ... Timer pin, 31 ... Oil passage hole, 53 ... Spill hole.

Claims (1)

[Scope of utility model registration request] A plunger insertion hole 2 is formed directly in the pump body made of hard steel, a fuel chamber 4 is formed at an interrupted position of the plunger insertion hole 2, and the plunger 3 is reciprocated within the plunger insertion hole 2 to supply fuel. An oil passage hole is fitted in the fuel chamber 4 on the outside of the plunger 3 and communicated with the top portion 3a of the plunger 3 by being rotated relative to the plunger 3. 31 to control the amount of fuel to be injected by changing the opening/closing timing of the plunger 3, and to control the injection timing of the fuel by being displaced in the axial direction of the plunger 3. In the injection pump, the fuel chamber 4 is formed in the shape of a concave hole extending inward from the outer peripheral surface of the pump body 1, and the inner wall surface 4b thereof is an inclined surface,
The annular valve 5 has a spill hole 53 that communicates with the oil passage hole 31 and spills the pressurized fuel in the plunger insertion hole 2 in order to terminate fuel injection.
The fuel injection pump is characterized in that it opens towards a position suitably offset from the deepest part of the inner wall surface 4b of the fuel chamber 4 in the recess direction.