JPH0494451A - Fuel injection pump for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent seizure between a tappet roller and a tappet pin by supporting a tappet body slidably and a cam rotatably, and providing a pump housing having a cam chamber filled with lubricating oil. CONSTITUTION:When lubricating oil is allowed to flow in a cam chamber 15 through an inflow port 16 from an oil pump, air, placed in the cam chamber 15 before an inflow of the lubricating oil, passes through a holding hole 12 and a communication hole 13 of a tappet body 11 or through a clearance between an internal wall surface of a pump housing 6 and an external peripheral surface of the tappet body 11 to escape to a side of a spring chamber 14. Consequently, the cam chamber 15 is filled with lubricating oil. In the lubricating oil with which the inside of the cam chamber 15 is filled, in the case that the tappet body 11, driven in a reciprocating direction through a tappet roller 9 and a tappet pin 10 by rotating a cam 8, is lowered downward, when a pressure is increased to the opening pressure of a valve unit of a pressure regulating valve 17, the lubricating oil is infiltrated into a clearance between the tappet roller 9 and the tappet pin 10 by this pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection pump for an internal combustion engine, such as a diesel engine.

[Prior Art] Recently, as a measure to purify the exhaust gas of diesel engines, the pressure of fuel injection pumps has been rapidly increased.

In conventional size-type fuel injection pumps, with such high pressure, the load applied to the plunger drive unit, tappet, and cam that generates high pressure increases, and the tappet components such as the tappet pin, tappet roller, tappet body, and Peeling and pitting of the cam surface are likely to occur.

As a countermeasure to this problem, a conventional technique (see Japanese Utility Model Publication No. 51-21234 etc.) exist.

[Problems to be Solved by the Invention] However, in the prior art, between the tappet roller and the tappet bin, there is a need for the tappet roller and the tappet bin to move integrally in the reciprocating direction. Since there is only enough clearance to rotate without rattling, the lubricating oil cannot be spread sufficiently even if the lubricating oil level is secured, and there is a possibility that seizing may occur between the tappet roller and the tappet bottle.

An object of the present invention is to provide a fuel injection pump for an internal combustion engine that can prevent seizure between the tappet roller and the tappet bin by supplying sufficient lubricating oil to the gap between the tappet roller and the tappet bin. .

[Means for Solving the Problems] The fuel injection pump for an internal combustion engine of the present invention includes a cam that is rotationally driven by the internal combustion engine, and a cam surface of the cam that is in contact with the cam surface of the cam.
A cylindrical tappet roller that is displaced in the reciprocating direction and the rotational direction, a tappet bin that is loosely fitted into the tappet roller, and a tappet roller that holds the tappet bin and rotatably supports the tappet roller, and is integral with the tappet roller. a tappet body that is movable in the reciprocating direction; a pump element that is connected to the tappet body and that pumps fuel supplied therein to the internal combustion engine; and a pump element that supports the tappet body so as to be slidable in the reciprocating direction; A technical means was adopted which includes a pump housing which rotatably supports the cam and has a cam chamber filled with lubricating oil.

[Operation] When the cam chamber of the pump housing that rotatably supports the cam is filled with lubricating oil, the reciprocating displacement of the tappet body, which is driven in the reciprocating direction via the tappet roller and tappet bin due to the rotation of the cam, causes the oil inside the cam chamber to be filled with lubricating oil. The pressure of the lubricating oil increases. The pressure of this lubricant
- By raising the tappet roller that comes into contact with the cam surface of the cam and the tappet pin that is loosely fitted into this tappet roller, 1! The lubricating oil is sufficiently distributed.

[Effects of the Invention] Since sufficient lubricating oil is distributed in the gap between the tappet roller and the tappet bottle, seizure between the tappet roller and the tappet bottle can be prevented.

[Example] The fuel injection pump for an internal combustion engine of the present invention is shown in FIGS. 1 to 5.
This will be explained based on an example shown in UXJ.

1 and 2 are diagrams showing the main parts of a size-type fuel injection pump used in a diesel engine, which is a first embodiment of the present invention.

The size fuel injection pump 1 includes a pump element 2, a coil spring 3, a camshaft 4, a tappet 5, and a pump housing 6.

The pump element 2 is composed of a tubular cylinder (not shown) and a cylindrical plunger 7, and as the plunger 7 moves upward in the drawing, an inclined groove formed in the plunger 7 is formed in a hole formed in the cylinder (not shown). 1), the fuel supplied into the cylinder is pumped toward the internal combustion engine.

The coil spring 3 biases the plunger 7 in the direction of the tappet 5 so that the plunger 7 always follows the reciprocating movement of the tappet 5.

The camshaft 4 is rotationally driven by an internal combustion engine, and by rotating the cam 8, the plunger 7 is displaced in a reciprocating direction (vertical direction in the drawing) via a tappet 5.

The tappet 5 includes a tappet roller 9, a tappet bin 10, and a tappet body 11.

The tappet roller 9 has a cylindrical shape, and the tappet bin 10
The outer circumferential surface of the cam 8 is in constant contact with the cam surface of the cam 8. This tappet roller 9 rotates in a direction opposite to the rotational direction of the cam 8, and is also displaced in a reciprocating direction (vertical direction in the drawing) due to the rotation of the cam 8.

Both ends of the tappet bin 10 are fitted and fixed to the tappet body 11, and a tappet roller 9 is rotatably disposed around the outer periphery of the central portion. Between the inner circumferential surface of the tappet roller 9 and the outer circumferential surface of the tappet bin 10,
A clearance is formed that allows the tappet roller 9 to rotate around the outer periphery of the tappet bin 10 without rattling.

The tappet body 11 rotatably holds the tappet roller 9 and has a holding hole 12 that opens toward the cam 8 side, and a communication hole 13 that communicates between the holding hole 12 and the side surface of the coil spring 3 is formed. has been done.

Further, the tappet body 11 is slidably displaced in a reciprocating direction (in the vertical direction in the drawing) with respect to the pump housing 6.

The pump housing 6 has an inner wall surface in contact with an outer circumferential surface of the tappet body 11, and supports the tappet body 11 so as to be slidable in a reciprocating direction (up and down directions in the figure).

The pump housing 6 has a spring chamber 14 in which the coil spring 3 is disposed, and a cam chamber 15 in which the cam 8 is disposed, and the spring chamber 14 and the cam chamber 15 are separated by a tappet body 11. .

Further, an inlet 16 is formed in the side wall of the cam chamber 15 of the pump housing 6 to allow lubricating oil to flow into the cam chamber 15 from an oil pump (not shown). A pressure regulating valve 17 is provided for regulating the pressure.

A side wall of the spring chamber 14 of the pump housing 6 is formed with an outlet 18 for returning lubricating oil in the spring chamber 14 to an oil pump or an oil pan (not shown).

The operation of this type fuel injection pump 1 will be explained based on FIGS. 1 and 2.

When lubricating oil flows from the oil pump into the cam chamber 15 through the inlet 16, the air that was in the cam chamber 15 before the lubricating oil flows into the holding hole 1 of the tappet body 11.
The spring escapes into the spring chamber 14@ through the communication hole 13 or the clearance between the inner wall surface of the pump housing 6 and the outer peripheral surface of the tappet body 11. Therefore, the cam chamber 15 is filled with lubricating oil.

Note that the lubricating oil filled in the cam chamber 15 is applied to the valve body of the pressure regulating valve 17 when the tappet body 11, which is driven in the reciprocating direction by the rotation of the cam 8 via the tappet roller 9 and the tappet bin 10, is lowered. When the pressure increases to the valve opening pressure, lubricating oil enters the clearance between the tappet roller 9 and the tappet bin 10 due to this pressure. Furthermore, the holding hole 12 and the communication hole 13 of the tappet body 11
The lubricating oil that has flowed into the spring chamber 14 through the spring chamber 14 lubricates the lubricated points within the spring chamber 14 and then flows out from the outlet 18 .

As a result, it is possible to prevent seizure between the tappet roller 9 and the tappet bin 10 due to insufficient lubrication.

Therefore, seizure between the cam 8 and the tappet roller 9 due to seizure between the tappet roller 9 and the tappet bin 10 can also be prevented.

FIG. 3 is a diagram showing the main parts of a fuel injection pump according to a second embodiment of the present invention.

In this embodiment, a throttle hole 17a is provided in place of the pressure regulating valve 17 of the first embodiment.
The pressure in the cam chamber 15 is increased by the throttle hole effect of a, thereby making it easier for lubricating oil to spread across the clearance between the tappet roller 9 and the tappet bin 10.

Therefore, in this embodiment, by using the throttle hole 17a instead of the pressure regulating valve 17, the cost can be reduced compared to the first embodiment, and the same effects as the first embodiment can be obtained. Note that the pressure inside the cam chamber 15 is controlled by the throttle hole 17.
It can be freely set by changing the diameter of a.

FIG. 4 is a third embodiment of the present invention, which is a diagram showing the main parts of a type fuel injection pump.

In this embodiment, the pressure regulating valve 17 of the first embodiment is abolished, and the communication hole 13 of the tappet roller 9 is replaced with the throttle hole 13a.
The pressure inside the cam chamber 15 is increased by the throttle effect of the throttle hole 13a, and the lubricating oil is easily distributed in the clearance between the tappet roller 9 and the tappet bin 10.

Therefore, in this embodiment, the only outlet for lubricating oil from the pump housing 6 is the outlet (not visible in the figure) 18, which reduces costs compared to the first and second embodiments. The same effects as in the second embodiment can be obtained. Note that the pressure inside the cam chamber 15 can be freely set by changing the diameter of the throttle hole 13a.

FIG. 5 is a fourth embodiment of the present invention, which is a diagram showing the main parts of a size-type fuel injection pump.

If the clearance between the tappet roller 9 and the tappet bin 10 allows the lubricating oil to flow from the cam chamber 15 to the spring chamber 14, the communication hole 13 of the tappet roller 9 may be eliminated as in this embodiment.

(Modification) In the first embodiment, the pressure inside the cam chamber 15 may be arbitrarily changed by the opening pressure of the pressure regulating valve 17.

In addition, in the first to fourth embodiments, if the amount of lubricating oil flowing in is too large and the pressure inside the cam chamber 15 rises too much,
As shown in FIG. 6, a throttle hole 16a may be provided in the inlet 16. Note that the pressure inside the cam chamber 15 can be freely set by changing the diameter of the throttle hole 16a.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention. 1st
The figure is a side sectional view showing the main parts of the size fuel injection pump, and FIG. 2 is another side sectional view showing the main parts of the size fuel injection pump. Fig. 3 is a second embodiment of the present invention, which is a side sectional view showing the main parts of a size-type fuel injection pump, and Fig. 4 is a third embodiment of the invention, showing the main parts of a size-type fuel injection pump. FIG. 5 is a side sectional view showing the main parts of a size-type fuel injection pump according to a fourth embodiment of the present invention. FIG. 6 is a side sectional view showing a modification of the present invention. In the diagram

Claims (1)

[Claims] 1) (a) a cam rotationally driven by an internal combustion engine; (b)
) a cylindrical tappet roller that comes into contact with the cam surface of the cam and is displaced in the reciprocating direction and the rotational direction; (c) a tappet pin that is loosely fitted into the tappet roller; (d) that holds the tappet pin. (e) a tappet body that rotatably supports the tappet roller and is displaced integrally with the tappet roller in a reciprocating direction; (f) a pump housing that slidably supports the tappet body in a reciprocating direction, rotatably supports the cam, and has a cam chamber filled with lubricating oil. Fuel injection pump.