JPH0326868A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To stabilize the feul injection quantity by installing a driving means for moving a plunger in reciprocation and a coil spring wound in the reverse direction in the inclination direction of an inclined groove for urging the plunger towards the driving means. CONSTITUTION:A plunger 4 having an inclined groove 44 inclined to one edge side and a coil spring 6 which is wound in the reverse direction in the inclination direction of the inclined groove 44 are assembled. Therefore, the fuel pressure in a cylinder 3 lowers, and the force due to the pressure waves and the reaction force of the coil spring 6 are offset each other when a hole 23 is opened and closed when the coil spring 6 returns to an extension position from a contraction position, and the plunger 4 is pressed only in the direction for increasing the injection quantity of fuel. Therefore, the dispersion of the injection quantity of fuel due to the revolution or non-revolution of the plunger 4 in the direction for reducing the injection quantity of the fuel is suppressed, and the fuel injection quantity can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection pump. [Prior Art] U.S. Pat. No. 4,793,316 discloses a runner having a right-sloping groove on its upper end. An in-line fuel injection pump is disclosed that includes a cylinder with holes at the ends for supplying and discharging fuel, and a right-handed coil spring that biases the plunger against a camshaft. In addition, in general, in-line fuel injection bombs change the positional relationship between the inclined groove and the hole, so that the hole is closed and opened from the time when the side surface of the upper end of the plunger closes the hole until it faces the inclined clear hole. is changing. Simply put, this changes the fuel delivery period during which the fuel supplied into the cylinder is pumped to the nozzle, or in other words, the amount of fuel injected. To change the relationship between the inclined groove and the hole, the force from the speed governor is transmitted to the driving face of the 7 plunger via the control rack, pinion, and control sleeve to rotate the plunger. This is done by Also, since the inclined groove is upwardly oriented to the right, the amount of fuel injected decreases when the plunger is rotated to the right, and increases when it is rotated to the left. [Problem to be Solved by the Invention 1] In general, in a row-type fuel injection bomb, when transitioning from the end of pumping to suction (opening and closing of holes), that is, when the plunger moves from top dead center to bottom dead center, As the pressure inside the cylinder decreases, the coil spring returns from the contracted position to the extended position. Therefore, in the rotation system of the plunger as described above, there is play due to factors such as manufacturing errors, so the force from the pressure wave and the reaction force of the coil spring combine to cause the plunger to rotate by a small amount. there's a possibility that.

However, since the above-mentioned conventional row-type fuel injection pump is constructed by combining a plunger with an upwardly sloping groove and a right-handed coil spring, the above-mentioned backlash causes one plunger to rotate clockwise by a small amount of rotation. There were cases where it rotated in the direction. That is, in the conventional in-line fuel injection pump described above, there is a possibility that the plunger rotates in a direction that reduces the amount of fuel injected by a minute amount. As a result, the amount of fuel injected becomes extremely unstable, and there is a problem in that the variation in the amount of injection between each cylinder is amplified. An object of the present invention is to provide a fuel injection pump that can stabilize the amount of fuel injected. [Means for Solving the Problems] A fuel injection pump of the present invention includes a cylinder having a hole on one end thereof for supplying and discharging fuel therein, and a cylinder disposed slidably within the cylinder. , a plunger having an inclined groove discharging the fuel supplied in the cylinder when aligned with the hole due to displacement; a drive means for reciprocating the plunger; and a plunger that moves the plunger in the direction of the drive means. and a coil spring wound in the opposite direction to the direction of inclination of the inclined groove. [Operation] The present invention combines a plunger having an inclined groove on one end thereof, and a coil spring wound in the opposite direction with respect to the direction of inclination of the inclined groove. Therefore, when the pressure of the fuel in the cylinder decreases and the coil spring returns from the contracted position to the extended position when the hole is opened or closed, the force caused by the pressure wave and the reaction force of the coil spring cancel each other out, resulting in the amount of fuel injected. Push the plunger in the direction that increases the value.
[Effects of the invention] By pressing the plunger only in the direction that increases the amount of fuel injected, variations in the amount of fuel injected due to the plunger rotating in the direction that decreases the amount of fuel injected or not rotating can be prevented. can. Therefore, it is possible to provide a fuel injection pump that can stabilize the amount of fuel injected.

[Example] The fuel injection pump of the present invention will be explained based on an example (not shown). Figure 1 shows an in-line fuel injection bomb employing the present invention. The in-line fuel injection pump 1 pumps the fuel supplied inside to a high-pressure pipe connected to the in-line fuel injection pump 1 and to a nozzle attached to each combustion chamber of the internal combustion engine. This in-line fuel injection pump 1 includes a bomb housing 2, a cylinder 3, a plunger 4, a driving means 5, a coil spring 6, a control sleeve 7, and a control rack 8. The pump housing 2 holds each part and protects the inside. The cylinder 3 has a tubular shape, and has a fuel discharge port 31 formed at its upper end. It has a hole 32 formed on the side of the tt end and a shaft hole 33 formed inside. In addition, the discharge port 3
1 is provided with a delivery valve 34 that opens only when fuel is being pumped. The hole 32 functions as a supply port for supplying fuel from the fuel chamber 35 into the cylinder 3 during suction, and also as a discharge port for discharging the fuel in the cylinder 3 to the fuel chamber 35 at the end of pumping. The plunger 4 has a tubular shape, is disposed within the shaft hole 33 of the cylinder 3, and is reciprocated in the vertical direction by the driving means 5. This plunger 4 has an opening 41 formed at its upper end.
．． A driving face 42 provided at the lower end, a shaft hole 43 formed inside, and a slanted groove 4 rounded at one end.
It has 4. The opening 41 communicates with the shaft hole 33 of the cylinder 3. The driving face 42 has a width in two directions so that when the control sleeve 7 rotates, the plunger 4 also rotates integrally with the plunger 4, and the plunger 4 can move relative to the control sleeve 7 in the reciprocating direction. The shaft hole 43 is connected to the shaft hole 33 of the cylinder 3 at the end of pressure feeding.
The interior of the fuel chamber 35 is communicated with the fuel chamber 35 via the inclined groove 44 and the hole 32. The inclined groove 44 is
It is inclined at a predetermined angle so that the right end is closer to the upper end of the plunger 4 than the left end, that is, to the upper right. The shaft hole 43 and the inclined groove 44 are connected to the hole 32 and the inclined groove 4.
4 coincides (completion of pressure feeding), the shaft hole 33 of cylinder 3
It acts as a discharge passage for discharging the fuel inside to the fuel chamber 35. Furthermore, since the inclined groove 44 of the 1 runger 4 rises to the right, the amount of injection decreases when rotated to the right, and increases when rotated to the left. Hereinafter, in this embodiment, plunger 4
The clockwise rotation of the plunger 4 is called the decreasing direction, and the counterclockwise rotation of the plunger 4 is called the increasing direction. The drive means 5 has a camshaft 51 and a tabet 52. The camshaft 51 is rotationally driven by an internal combustion engine, and by rotating the cam 53, the plunger 4 is reciprocated via the tabet 52. The coil spring 6 is wound in the opposite direction with respect to the direction of inclination of the inclined groove 44, that is, counterclockwise. The first runger 4 is urged in the direction of the tabet 52 so that the first runger 4 always follows the reciprocating movement of the tabet 52. Further, the coil spring 6 has an upper end fixed to an annular retainer 61 disposed around the outer periphery of the control sleeve 7, and a lower end fixed to an annular retainer 62 disposed around the outer periphery of the lower end of the plunger 4. ．． The control sleeve 7 has a tubular shape, is rotatably disposed around the outer periphery of the cylinder 3, has a pinion 71 at its upper end that engages with the control rack 8, and has a plunger 4 at its lower end.
It has a connecting portion 72 that connects to the driving face 42 of the vehicle. The control rack 8 is a governor (adjuster) not shown.
and pinion 71, and control sleeve 7
1 runger 4 is rotated through the hole 32 and the slope 71.
By changing the positional relationship with 1I44, the injection timing and injection amount are changed. The operation of the fuel injection pump of this embodiment is explained in the second Uf! This will be explained based on Figures U to 5. ■． Suction stroke As shown in FIG. 2, when the first plunger 4 descends and is located at the bottom dead center, the E end of the first plunger 4 opens the hole 32 formed in the cylinder 3, so that the hole is removed from the fuel chamber 35. 32, fuel is supplied into the shaft hole 33 of the cylinder 3. [At the start of 4th feed, the camshaft 51 rotates, the plunger 4 rises,
As shown in FIG. 3, when the upper end surface of the plunger 4 coincides with the upper end of the hole 3z, pressure feeding of fuel is started. At this time, a force is applied to the plunger 4 in the decreasing direction due to the load [S] of the coil spring 6. However, since the frictional force If caused by sliding between the inner circumference of the cylinder 3 and the outer circumference of the plunger 4 is greater than the load Is of the coil spring 6, the plunger 4 does not rotate. ■, Pressure feeding stroke, and the rotation of the camshaft 51 causes the plunger 4 to
When the plunger 4 rises, the side surface of the upper end of the plunger 4 closes the hole 32. At this time, the pressure of the fuel supplied into the shaft hole 33 of the cylinder 3 is increased by the rise of the plunger 4, which presses the delivery valve 34 and is forced into the high pressure pipe and nozzle.

Further, the load Is of the coil spring 6 applies a force to the first plunger 4 in the decreasing direction. However, since the frictional force 1f between the inner circumference of the cylinder 3 and the outer circumference of the first plunger 4 is greater than the load [S] of the coil spring 6, the first plunger 4 does not rotate. ■． When the pressure feeding is finished, the plunger 4 is further rotated by the rotation of the camshaft 51.
4, as shown in FIG.
4 is coming. At this time, the high-pressure fuel above the first plunger 4 in the shaft hole 33 of the cylinder 3 is pushed back from the hole 32 to the fuel chamber 35 through the shaft hole 43 of the first plunger 4 and the inclined fuel 44. The pressure inside the hole 33 decreases and the pumping of fuel ends. Also, the force I due to pressure waves
A force is applied to the plunger 4 in the increasing direction due to p, and a force is applied to the plunger 4 in the decreasing direction due to the reaction force Is of the coil spring 6. At this time, the force 1p due to the pressure wave caused by the pressure drop etc. becomes larger than the reaction force Is of the coil spring 6, and the 1 plunger 4 rotates by a minute rotation in the increasing direction.

■． When the hole 32 is opened/closed As shown in FIG. 5, when transitioning from the end of pressure feeding to the suction stroke, the pressure inside the shaft hole 33 of the cylinder 3 decreases and the coil spring 6 contracts due to the reaction force. The plunger 4 returns from the position to the extended position, and the plunger 4 is displaced from the top dead center to the bottom dead center. At this time, since the row type fuel injection pump 1 of this embodiment is configured by combining the 1 runger 4 having the upwardly sloping groove 44 and the left-handed coil spring 6, the 7 runger 4 is at the top dead center. When the plunger is displaced from to the bottom dead center, a force 1p due to the pressure wave applies a force in the decreasing direction to the plunger 4, and a reaction force Is of the coil spring 6 applies a force to the plunger 4 in the increasing direction. At this time, since the force 1p due to the pressure wave is smaller than the reaction force Is of the coil spring 6, the first plunger 4 descends while rotating in the increasing direction by a minute amount. That is, the plunger 4 always descends while rotating by a minute rotation in the increasing direction and is pressed against the tabet 52. Therefore, the in-line fuel injection pump 1 that occurs when the plunger rotates or does not rotate in the downward direction.
It is possible to prevent variations in the amount of injection.

Therefore, since each plunger 4 of the in-line fuel injection bomb 1 all rotates by a minute rotation in the increasing direction, the amount of injection into each cylinder of the internal combustion engine is stabilized, and variations in the amount of injection between each cylinder are reliably suppressed. be able to.

[Other Examples] In this example, a plunger with an upwardly sloping groove and a left-handed coil spring was combined, but a plunger with an upwardly sloping groove and a right-handed coil spring was combined. Also good. In this embodiment, the driving means is composed of a camshaft and a tappet, but the driving means may also be composed of only a camshaft.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a row-type fuel injection pump adopted in an embodiment of the present invention, and FIGS. 2 to 5 are explanatory diagrams showing the stroke of a plunger incorporated in the row-type fuel injection pump. ．． In the diagram

Claims (1)

[Scope of Claims] 1) (a) A cylinder having a hole along one end thereof for supplying and discharging fuel; (b) A cylinder disposed slidably within the cylinder;
a plunger having, on one end thereof, an inclined groove for discharging the fuel supplied in the cylinder when the plunger is aligned with the hole due to displacement; (c) driving means for reciprocating the plunger; (d) the driving means; A fuel injection pump comprising: a coil spring wound in the opposite direction to the direction of inclination of the inclined groove for biasing the plunger in the direction of the device.