JPH02248647A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To improve injection quantity accuracy by connecting a connecting lever connected to a plunger or a relatively rotatable control ring to a control rod in such a manner as to be adjustable, and adjusting the rotating quantity of a rotating member to regulate only the fuel injection quantity characteristic in a specified area. CONSTITUTION:A pump chamber is formed in the cylinder of a fuel injection pump, and a fuel introducing hole and a discharge valve are provided. One end of a plunger 10 is inserted into the cylinder to pressurize fuel. A fuel release passage is formed in the inside of the plunger 10 and communicated to a control channel formed with a gradient to the plunger shaft. A sleeve 21 is fitted on the outer circumference of the plunger 10 in such a manner as to be integrally rotatable to fix a connecting ring 22, and a connecting lever 25 is connected to a control rod 28 in such a manner that protruding quantity l can be adjusted by an adjusting screw 24. Even if the stroke of the control rod is constant, the injection quantity can be regulated by changing the rotating quantity to improve the injection quantity accuracy.

Description

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

[Conventional technology]

For example, a size fuel injection pump that supplies fuel to a diesel engine is designed to control the fuel injection amount and fuel injection timing depending on the operating conditions of the engine.

That is, in the conventional size fuel injection pump described in Japanese Utility Model Publication No. 33-16507, a cylinder is fitted into a housing, a pump chamber is formed inside the cylinder, and the pump chamber is connected to the cylinder through a discharge valve. The plunger is connected to the fuel injection valve, and one end of the plunger is slidably inserted into the pump chamber of the bracket.

The other end of the plunger is in rolling contact with a cam driven in synchronization with the rotation of the engine via a cam roller, and is reciprocated by the operation of this cam. A control groove inclined with respect to the axis of the plunger is opened in the outer peripheral surface of the plunger, and this control groove communicates with the pump chamber through a communication passage formed inside the plunger.

This control groove opens and closes a fuel introduction hole opened in the side wall of the cylinder.

A sleeve is fitted around the outer periphery of the plunger so as to rotate together with the plunger, and this sleeve is connected to the control rod via a connecting lever.

The control rod is disposed outside the plunger in a direction perpendicular to the plunger, and is moved linearly by the control governor depending on the operating conditions of the engine.

In such a fuel injection pump, when the plunger is reciprocated by the operation of the cam, one end of the plunger pressurizes the fuel in the pump chamber introduced from the fuel introduction hole,
The discharge valve is pushed open to send fuel to the fuel injection valve, through which it is supplied to the combustion chamber of the engine.

At this time, when the control rod is linearly moved by the control governor according to the engine operating conditions, the plunger is rotated around its axis via the connecting lever and sleeve, and the inclined control groove formed in the plunger is displaced. Therefore, the timing of closing the fuel inlet hole is changed by the flow groove, and the fuel pressurization stroke is accordingly changed, so that the fuel injection amount is adjusted to:A.

[Problem to be solved by the invention]

By the way, recently with this type of fuel injection pump,
There is a tendency that there is an increasingly strong demand for improvement in injection amount accuracy.

However, in general, in fuel injection pumps, it is inevitable that the accuracy of the injection amount will be slightly reduced due to processing and assembly errors. Therefore, it is desirable to correct the decrease in injection amount accuracy due to such errors and variations at the end of product assembly.

However, with the above-mentioned conventional fuel injection pump, when the injection amount in the idle region is adjusted with high precision, the injection amount in the rated output region also changes relatively accordingly. There is a problem that the accuracy of the injection amount in the area decreases.

In other words, if adjustments are made to obtain highly accurate injection characteristics in a certain injection amount area, other injection amount areas will also be adjusted, and the characteristics will actually worsen in other injection amount areas that do not require adjustment. There is a problem.

The present invention has been developed based on the above circumstances, and it is possible to adjust only the injection amount area that requires adjustment so as to obtain highly accurate injection characteristics, and in this case, other injection amount areas are not affected. The object of the present invention is to provide a fuel injection pump that avoids this problem.

[Means to solve the problem]

In order to achieve the above object, the present invention forms a pump chamber inside a cylinder provided in a pump housing, and a plunger whose one end is slidably inserted into the pump chamber is driven by an engine. The plunger is brought into contact with a cam and reciprocated by the operation of the cam, and a control groove is provided on the side surface of the plunger that is connected to the pump chamber via a fuel relief passage and is opened at an angle with respect to the plunger axis. A rotatable member of the plunger, the cylinder, or a control ring provided to be rotatable relative to the plunger is connected to a control rod, and the control rod is linearly moved by a governor to cause the rotation. In a fuel injection pump that controls the fuel injection amount by the inclined control groove by rotating a member, a connecting lever is connected to the rotating member, and a protruding end of the connecting lever is connected to the control rod. The amount of protrusion of the connecting lever from the rotating member can be adjusted, and the connecting position of the connecting lever and the control rod can be moved in a direction perpendicular to the direction of movement of the control rod. Features.

[Effect]

According to the configuration of the present invention, even if the operating stroke of the control rod by the governor is the same, the amount of rotation of the rotating member of the plunger, cylinder, or control sleeve is adjusted by adjusting the amount of protrusion of the connecting lever from the plunger. can be changed. Therefore, the timing at which the control groove releases fuel from the pump chamber, that is, the fuel pumping stroke, can be changed, and the fuel injection amount can therefore be adjusted. In this case, although the operating stroke of the control rod remains the same, the amount of rotation of the rotating member that controls the fuel injection amount changes, so only the fuel injection amount characteristics in a specific region can be changed.

〔Example〕

The present invention will be described below based on an embodiment shown in the drawings.

FIG. 3 is a sectional view showing the entire row type fuel injection pump, and 1 is a pump housing.

A cylinder 2 is fitted into the pump housing 1, and a pump chamber 3 is formed in the cylinder 2.

A discharge port body 4 is attached to the upper end of the pump housing 1, and the discharge port body 4 is connected to a fuel injection valve of an engine via a vibrator (not shown).

A discharge valve 5 is accommodated in the discharge port body 4, and this discharge valve 5 faces the pump chamber 3. When the fuel pressure in the pump chamber 3 exceeds the valve opening pressure set by the pressing force of the discharge valve spring 6, the valve body 7 is lifted, and the high pressure fuel pressurized in the pump chamber 3 is thereby transferred to the discharge port body 4. However, the fuel is sent under pressure to the engine's fuel injection valve.

A fuel introduction hole 8 is opened in the side wall of the cylinder 2.
This fuel introduction hole 8 communicates with a fuel chamber 9 formed around the cylinder 2 in the pump housing l.

Therefore, fuel in the fuel chamber 9 is introduced into the pump chamber 3 through the fuel introduction hole 8 . Note that fuel is supplied to this fuel chamber 9 from a fuel supply pump (not shown).

One end of a plunger 10 is slidably inserted into the cylinder 2.

This plunger 10 also serves as a rotating member of the present invention,
One end faces the pump chamber 3 and pressurizes the fuel in the pump chamber 3.

As shown in FIG. 2, inside the plunger 10, a fuel relief passage 11 is formed, one end of which opens at the upper end of the plunger 10 and communicates with the pump chamber 3. The other end communicates with a control groove 12 opened on the side surface of the plunger 10. This control groove 12 is formed on the side surface of the plunger 10 so as to be inclined with respect to the direction of the plunger axis. This control groove 12 communicates with the fuel introduction hole 8 when the plunger 10 is raised, and at this time, the fuel in the pump chamber 3 is transferred from the fuel relief passage 11 to the fuel chamber 9 through the control groove 12 and the fuel introduction hole 8. It is set to return to .

The other end of the plunger 10 is guided to the lower part of the pump housing 1, and a spring seat 13 is connected to this lower end.

The lower end of a return spring 14 is in contact with this spring seat 13 . The upper end of the return spring 14 is in contact with another spring seat 15 provided on the housing 1, so that the plunger 10 is constantly pushed downward by the urging force of the return spring 14.

A spring seat 13 connected to the lower end of the plunger 10 is in contact with a tappet 16, and this tappet 16 rotatably supports a cam roller 17.

Cam roller 17 is in contact with cam 18.

That is, a cam chamber 19 is formed at the lower end of the housing 1, and a cam shaft 2o rotated by the crankshaft of the engine is introduced into this cam chamber 19, and the cam 18 is mounted on this cam shaft 20. It is formed.

Therefore, the camshaft 20 rotates in synchronization with the rotation of the engine.1. As a result, the cam 18 rotates together, and the plunger 10 is pushed up via the cam roller 17. Then, when the plunger 10 passes the top dead center, the plunger 10 is pushed down by the urging force of the return spring 14, so that the plunger 10 is reciprocated.

A sleeve 21 is fitted onto the outer periphery of the plunger 10 so as to rotate together with the plunger 10 by means such as engagement of the width across flats (not shown). A connecting ring 22 is fixed to this sleeve 21.

As shown in FIG. 1, the connecting ring 22 is separated at a part in the circumferential direction, and these separated ends are connected by a tightening screw 23, and by tightening this tightening screw 23, the diameter of the connecting ring 22 is reduced. The coupling ring 22 is thereby secured to the outer periphery of the sleeve 21.

An adjusting screw 24 is screwed into the center of the tightening screw 23, and the adjusting screw 24 can move forward and backward relative to the tightening screw 23. A connecting lever 25 is slidably protruded from one separated end of the connecting ring 22, and a flange 26 is formed on the connecting lever 25 so as to face the adjusting screw 24. A return spring 27 is provided between this flange 26 and one separated end of the connecting ring 22, so that the flange 26 of the connecting lever 25 is pressed against the adjusting screw 24.

Therefore, when the adjusting screw 24 is screwed back and forth, the connecting lever 2
5 protrusion ff1j) is adapted to be changed.

A control rod 2 is provided on the side of the connection ring 22.
8 is provided. The control rod 28 is slidably attached to the pump housing 1 so as to be orthogonal to the plunger 10, and is connected to a fuel injection amount control governor (not shown) attached to the outside of the pump housing 1.

The fuel injection amount control governor is designed to linearly reciprocate the control rod 28 in the longitudinal direction, that is, in the direction of arrow A in FIG. The linear movement of the control rod 28 causes the coupling ring 22 and sleeve 21 to rotate via the coupling lever 25, so that the plunger 10 is rotated around the axis.

Note that the operating stroke L of the control rod 28 is automatically adjusted by a fuel injection amount control governor according to the operating conditions of the engine.

A bent portion 29 is formed at the tip of the connecting lever 25, and this bent portion 29 is slidably engaged with a sliding engagement groove 30 formed in the control rod 28. The sliding engagement groove 30 extends in a direction perpendicular to the longitudinal direction of the control rod 28, and when the protrusion amount g of the connecting lever 25 is changed, the bent end portion 29 moves into the sliding engagement groove 30.
It can be displaced along.

The operation of an embodiment of such a configuration will be explained.

When the plunger 10 descends following the cam surface of the cam 18 rotated by the engine, the upper end surface of the plunger 10 falls below the fuel introduction hole 8 of the cylinder 2, and the fuel in the fuel chamber 9 flows into the pump chamber 3. be introduced.

When the fuel introduction hole 8 begins to be closed by the upper end surface of the plunger 10 while the plunger 10 is raised by the action of the cam 18, the fuel in the pump chamber 3 begins to be pressurized by the plunger 10, and this fuel introduction hole 8 is plunger 10
When the upper end surface is completely blocked, the fuel in the pump chamber 3 has no place to escape, and when the fuel pressure in the pump chamber 3 exceeds the opening pressure of the discharge valve 5, the valve is lifted, and the pump chamber 3 The high-pressure fuel is pumped from the discharge port body 4 to the fuel injection valve of the engine.

The plunger 10 continues to rise, and this plunger 10
When the control groove 12 opened on the side surface is connected to the fuel introduction hole 8, the fuel in the pump chamber 3 is released from the fuel relief passage 11 to the fuel chamber 9 through the control groove 12 and the fuel introduction hole 8. Since the fuel pressure in the fuel tank 3 decreases, the discharge valve 5 closes and stops supplying fuel.

The plunger 10 rises to the top dead center, and after passing the top dead center, it descends following the cam surface of the cam 18, and descends to the bottom dead center.

During this time, when the control groove 12 falls below the lower edge of the fuel introduction hole 8 and the upper end surface of the plunger 10 falls below the fuel introduction hole 8, the fuel in the fuel chamber 9 is introduced into the pump chamber 3.

Thereafter, the above operation is repeated.

In order to control the fuel injection amount, a fuel injection amount control governor is operated according to the operating condition of the engine, thereby moving the control rod 28 in the direction of arrow A in FIG. Then, the connecting lever 25 engaged with the sliding engagement groove 30 formed in the control rod 28
The connecting ring 22 and the sleeve 21 are rotated as shown in phantom lines in FIG.

Therefore, the plunger 10 is rotated around the axis, and the diagonal control groove 12 formed in the plunger 10 is also rotationally displaced.

Therefore, during the fuel pressurization process of the plunger 10, the timing at which the lead surface of the control groove 12 communicates with the fuel introduction hole 8 changes, that is, the stroke for pressurizing the fuel in the pump chamber 3 by the plunger 10 changes, so the fuel injection amount can be increased or decreased.

For example, if the position of the control groove 12 is al as shown in FIG. 2 during idling, then the stroke of the plunger 10 until the control groove 12 communicates with the fuel introduction hole 8 is SL, Therefore, the plunger 10 injects fuel corresponding to the stroke S1.

On the other hand, at the rated output, the control rod 28 is moved by the stroke L in the direction of the arrow in FIG. Move.

In this case, the stroke of the plunger 10 until the control groove 12 communicates with the fuel introduction hole 8 is S2, and therefore the plunger 10 injects fuel corresponding to the stroke S2.

By the way, if the injection amount accuracy in a certain region is low due to variations in processing errors or assembly errors of the pump, it can be corrected as follows.

For example, if you want to adjust the injection amount in the rated output area,
The protruding length g of the connecting lever 25 is adjusted to rt by operating the adjusting screw 24 shown in FIG.

In this case, the bent end portion 29 of the connecting lever 25 is slidably engaged along the sliding engagement groove 30 extending in a direction perpendicular to the longitudinal direction of the control rod 28, so that the initial position of the control rod 28 is does not change.

That is, since the position al of the control groove 12 does not change during idling, the stroke St of the plunger 10 does not change, and the fuel injection amount corresponds to a stroke of 81 minutes.

On the other hand, at the rated output, when the control rod 28 is moved by the stroke L due to the action of the governor, the protruding length of the connecting lever 25 increases (N-1
1), the rotation angle of the plunger 10 is θ1 (a
lkuθ). That is, even if the stroke L of the control rod 28 by the governor does not change, the plunger 1o
The rotation angle θl is: A node. This moves the position of the control groove 12 to 82°.

In this case, the stroke of the plunger 10 until the control groove 12 communicates with the fuel introduction hole 8 is S2',
Therefore, the plunger 1o injects fuel corresponding to the stroke S2°, and in this example, the injection amount in the rated output region can be reduced.

Therefore, when the protruding length of the connecting lever 25 is extended as described above, the fuel injection amount in the rated output region can be adjusted without changing the fuel injection amount in the idle region, and the injection amount in both regions can be adjusted. Accuracy can be increased.

Note that when the protruding length of the connecting lever 25 is shortened, the fuel injection amount in the rated output region can be increased without changing the fuel injection amount in the idling region.

In the case of this embodiment, such an adjustable range depends on the amount of adjustment of the protrusion length of the connecting lever 25, but theoretically it is the width dimension of the control rod 28, that is, the length of the sliding engagement groove 30. is adjustable, and the 2 shown in Figures 5 and 6
Corresponds to Δθ minutes.

Therefore, for example, if a machining error occurs in the lead angle ρ of the control groove 12, this error will be
This error can be corrected within the range of Δρ corresponding to Δθ.

Note that the present invention is not limited to the above embodiments.

That is, in the above embodiment, in order to control the fuel injection amount, the control rod 28 is operated by the governor.
In the above, the plunger 10 is rotated, but instead of the plunger 10, the cylinder 2 may be rotated relative to the plunger 10.

Furthermore, in the case of in-line fuel injection pumps,
As seen in Japanese Patent No. 118936, etc., a control sleeve is inserted into the plunger separately from the cylinder so as to be rotatable in the axial direction and around the axis, and the control sleeve and the plunger are relatively operated by a governor. A type of fuel injection valve in which the amount of fuel injection is controlled by rotating a control rod is also known, and the present invention can be practiced even with a type of fuel injection valve equipped with such a special control sleeve.

In this case as well, the plunger may be rotated or the control sleeve may be rotated.

〔Effect of the invention〕

As explained above, according to the present invention, by adjusting the amount of protrusion of the connecting lever from the plunger, even if the operating stroke of the control rod is the same, the rotating member of the plunger, cylinder, or control sleeve can be rotated. By changing the amount of movement, the fuel pumping stroke can thus be changed and thus the fuel injection amount can be adjusted. In this case, although the operating stroke of the control rod remains the same, the amount of rotation of the rotating member that controls the fuel injection amount changes, so it is possible to change only the fuel injection amount characteristics in a specific region, i.e., Fl in a certain region. It is possible to adjust only the fuel injection amount characteristics in a desired range without changing the fuel injection amount characteristics, and it is possible to improve the injection amount accuracy over the entire area.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a cross-sectional view of the connection between the control rod and the plunger, FIG. 2 is a perspective view of the cylinder and plunger, FIG. 3 is a cross-sectional view of the entire fuel injection pump, and FIG. 4 to 6 are diagrams each explaining the operation. DESCRIPTION OF SYMBOLS 1...Housing, 2...Cylinder, 3...Pump chamber, 8...Fuel introduction hole, 10...Plunger, 1
1... Fuel relief passage, 12... Control groove, 1
8...Cam, 22...Connection ring, 23...Tightening screw, 24...Adjustment screw, 25...Connection lever
28... Control rod, 30... Sliding engagement groove. Figure 1 Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure Figure Figure Figure

Claims (1)

[Claims] A pump chamber is formed inside a cylinder provided in the pump housing, and one end of the plunger is slidably inserted into the pump chamber.The other end of the plunger is brought into contact with a cam driven by the engine to operate the cam. In addition, a control groove is provided on the side surface of this plunger that is connected to the pump chamber via a fuel relief passage and is opened at an angle with respect to the plunger axis. The tilted control is achieved by connecting one of the rotatable members of the control rings provided so as to be relatively rotatable to a control rod, and moving the control rod linearly by a governor to rotate the rotatable member. In a fuel injection pump that controls the fuel injection amount using a groove, a connecting lever is connected to the rotating member, a protruding end of the connecting lever is connected to the control rod, and the connecting lever is connected to the rotating member. A fuel injection pump characterized in that the amount of protrusion of the connecting lever can be adjusted, and the connecting position of the connecting lever and the control rod can be moved in a direction perpendicular to the direction of movement of the control rod.