JPH01244158A - Distributor type fuel-injection pump - Google Patents

Abstract

PURPOSE:To secure a stable, accurate compensation value as well as to prevent a noise from occurring by forming an incline moving a roller holder in the double-acting direction of a cam plate when this roller holder is rotatively displaced with a pressure buildup in fuel in a fuel chamber. CONSTITUTION:When a roller holder 31 is rotatively displaced with the increase of engine speed, a projection 31c comes into contact with an incline 27a, and the roller holder 31 is moved in direction of separating from a control sleeve 17 as far as a portion conformed to the rotational displacement of the roller holder 31. Following this movement, a cam plate 19 and a plunger 15 are moved in the same direction by energizing force of a spring. In consequence, a cutoff port 15c of the plunger 15 is delayed at its timing to be exposed out of the control sleeve 17, whereby an injection quantity is compensated for increment as much a portion for that. Here pressure of fuel in a fuel chamber is constant unless the engine speed is not varied, and the roller holder 31 also maintains its constant position. Consequently, the fuel injection quantity can be accurately compensated in a stable manner and, what is more, a noise is in no case emitted there.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a distribution type fuel injection pump that automatically increases the amount of fuel injected in response to an increase in engine speed. .

[Conventional technology 1 Generally, in a direct injection specification distribution type fuel injection pump,
When the position of the control sleeve is held constant, there is a tendency for the amount of fuel injection to decrease as the engine rotates at higher speeds. If this tendency is left as it is, the problem will be that the engine output will be insufficient in the high speed rotation range.

Therefore, in the distribution type fuel injection pump with direct injection specifications,
The fuel injection amount is corrected to increase in a high speed rotation range, and a distribution type fuel injection pump having such a correction mechanism is described in, for example, Japanese Utility Model Application Publication No. 140170/1983.

As shown in FIG. 6, the distribution type fuel injection pump described in this publication includes a plunger 2 whose one end is slidably provided in a pump housing 1, and a plunger which protrudes from the pump housing 1 into a fuel chamber 3. When the plunger 2 moves forward in the direction of arrow A, the fuel in the fuel pressurizing chamber 1a is pressurized and the vertical hole is Fuel is fed under pressure to a fuel injection nozzle (not shown) through the horizontal hole 2a, the horizontal hole 2b, and the supply hole 1b. Then, when the off-board 2C of the plunger 2 is exposed from the control sleeve 4, fuel injection ends. Conversely, when the plunger 2 moves backward in the direction of arrow B, the fuel in the fuel chamber 3 is sucked into the fuel pressurizing chamber la through the suction hole 1c and the vertical groove 2d.

In addition, in order to correct the fuel injection amount in the high speed rotation range, in this fuel injection pump, the control sleeve 4 moves the sleeve body 4a, slider 4b, stopper 4c, and slider 4b in the direction of backward motion of the plunger 2. The quantity ratio of the sleeve body 4a and the slider 4b is such that the fuel introduction chamber 4e, which is communicated with the fuel pressurizing chamber 1a through the through hole 2d and the vertical hole 2a, It is formed.

In the above configuration, when the plunger 2 moves forward, the fuel pressurized in the fuel pressurizing chamber la is introduced into the fuel introduction chamber 4e, and the pressing force of this fuel causes the slider 4b to resist the urging force of the bone 4d. This causes the plunger 2 to move in the forward movement direction. Then, the pressing force of the fuel and the spring 4
It stops at the position where the urging force of d is balanced. As a result, the cutoff bow is the amount that slider 4b has moved)
2c is exposed from the slider 4b, and the fuel injection amount is corrected to increase accordingly. Here, the pressure of the fuel in the fuel pressurizing chamber 1a increases as the moving speed of the plunger 2 becomes faster and as the engine speed increases, so as the engine speed increases, the pressure of the fuel in the slider 4b increases. The amount of movement also increases. Therefore, the fuel injection amount is corrected in accordance with the engine speed.

Note that the maximum correction amount is regulated by the slider 4b hitting the stopper 4c.

[Problem to be solved by No. 4] In the above conventional distribution type fuel injection pump, the cutoff port 2c is connected to the control sleeve 4 (slider 4b).
), the pressure inside the fuel introduction chamber 4e decreases, and the slider 4b is returned to its original position by the biasing force of the bone 4d! Then, when the plunger 2 moves forward again and the fuel in the fuel pressurizing chamber la is pressurized, the plunger
The jar 2 is moved in the forward movement direction. In other words, the slider moves back and forth. As described above, since the slider 4b constantly repeats reciprocating motion, the amount of correction is not constant even when the engine speed is constant, which causes problems such as instability and inaccuracy. Also, the slider 4b
Since the sleeve body 4a repeatedly collides with the stopper 4C, there is a problem in that noise is generated.

This invention was made in order to solve the above problem, and it is possible to obtain a stable and accurate correction amount, while also producing noise and 2.
The purpose of the present invention is to provide a distribution type fuel injection pump that does not cause problems.

[Means for Solving the Problems 1] The present invention has been made by focusing on the point that the roller holder of the timer mechanism is rotationally displaced so as to advance the fuel injection timing as the engine speed increases, and is based on the above-mentioned problem. In order to achieve this purpose, the roller holder is provided so as to be movable in the reciprocating direction of the cam plate, and a protrusion is formed on one of the mutual contact surfaces of the roller holder and the pressure receiving member, and a protrusion is formed on the other side of the contact surface in the fuel chamber. The cam plate has an inclined surface that is inclined so that the protrusion comes into contact with the cam plate when the cam plate is rotated, and moves the roller holder in the direction of backward movement of the cam plate as the roller holder rotates as the fuel pressure increases. be.

[Effect 1] As the engine speed increases, the pressure of the fuel in the fuel chamber increases, and this causes the roller holder to rotate, causing the protrusion to come into contact with the inclined surface, and the roller holder to respond to the amount of rotation. The cam plate moves in the direction of the backward motion by the distance. As the roller holder moves, the cam plate and plunger move in the same direction. The timing at which the cutoff port of the plunger is exposed from the control sleeve is delayed by the distance traveled, and the fuel injection amount is increased by that amount.

Here, the pressure of the fuel in the fuel chamber does not change suddenly as the plunger moves, unlike the fuel in the fuel pressurizing chamber, and as long as the engine speed is constant, the pressure of the fuel changes very little. Therefore, although the roller holder rotates slowly as the engine speed changes, if the engine speed is constant, it stops at a fixed position. Therefore, a stable and accurate amount of correction can be obtained. Further, since the roller holder does not rapidly reciprocate, no noise is generated.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

In FIG. 4, reference numeral 11 denotes a pump housing in which a fuel chamber 12 is formed. This pump housing 1
A barrel 13 is disposed on one side wall of the barrel 1 . One end of a plunger 15 for pressurizing the fuel in the fuel pressurizing chamber 14 is slidably inserted into the barrel 13 . A mount roll sleeve 17 whose position is controlled by a tensile lever 16 is slidably fitted onto the outer periphery of the other end of the plunger 15 located within the fuel chamber 12 .

On the other hand, a drive shaft 18 rotatably driven by an engine (not shown) is rotatably inserted through the other side wall of the pump housing 11 with its axis aligned with the axis of the plunger 15. The fuel chamber 12 of this drive shaft 16
At the end located inside, the cam plate 19 is relatively unrotatable.
And they are connected so as to be relatively movable in the axial direction. A plunger 15 is fixed to this cam plate 19, and
A cam portion 19a is formed on the end face facing the drive shaft 16 side. This cam portion 19a is pressed into contact with a roller 30 of a roller holder 31 (described later) by the biasing force of a spring (elastic member) 20, and as a result, the cam plate 19 reciprocates at the same time as the rotation, and the plunger is moved together with the cam plate 19. 1
5 rotates and reciprocates.

In the above configuration, when the plunger 15 moves forward in the direction of arrow C, the fuel in the fuel pressurizing chamber 14 is pressurized,
The fuel is forcefully fed to a fuel injection nozzle (not shown) through the vertical hole 15a and horizontal hole 15b1 of the plunger 15, the supply hole 21, and the pre/pull nozzle 22. When the cut-off port (15c) of the plunger 15 is exposed from the control sleeve 17, fuel injection ends. Conversely, when the plunger 15 moves back in the direction of the arrow, the fuel in the fuel chamber 12 rises to the suction hole 23 and the plunger 1.
The fuel is drawn into the pressurizing chamber 14 through the vertical groove 15d of No. 5.

In addition, the inside of the fuel chamber 12 of the pump housing 11,
A feed pump 24 and a timer mechanism 28 are arranged. The feed pump 24 includes a casing 25 which is arranged and fixed on the inner wall surface of the pump housing 11 and whose center portion is penetrated by the drive shaft 18, and a rotor 26 which is arranged inside the casing 25 and rotationally driven by the drive shaft 18.
and a side plate (pressure receiving member) 27 that is fixed to the surface of the casing 25 facing the cam plate 19 and covers the gap between the casing 25 and the rotor 26, and when the rotor 26 rotates, the fuel tank (see Fig. (not shown) into fuel chamber 1.
It is designed to be sent into 2.

Therefore, the faster the rotor 26 rotates, the more the fuel chamber 12
The pressure of the fuel inside the tank will increase. In addition, fuel chamber 1
The maximum pressure of No. 2 is regulated by a pressure regulating valve (not shown).

On the other hand, the timer mechanism 28 is disposed between the feed pump 24 and the cam plate 19, and is configured as follows. That is, as shown in FIG. 5, the pump housing 11 is formed with a storage section 29 that communicates with the fuel chamber 12, and this storage section 29 has a roller holder 31 that rotatably supports the roller 30. It is housed so as to be rotatable and movable in the ring line direction of the plunger 15. However, the cam plate 19 is brought into pressure contact with the roller 30 by the biasing force of the spring 20, and thereby the roller holder 31 is brought into pressure contact with the side plate 27 of the feed pump 24.

Further, the pump housing 11 is formed with a cylinder portion 32 that communicates with the storage portion 29.
A piston 33 is slidably disposed on 2. This piston 33 is biased in one direction by a bone 34 disposed at one end of the cylinder portion 32, while the piston 33
3 is pressed in the other direction by fuel introduced into the other end of the cylinder portion 32 through an introduction hole 33a formed inside the cylinder portion 32. In addition, a rod 3 is provided at the center of the piston 33.
5 is locked at one end. The other end of this rod 35 is connected to engagement holes 31a and 31 formed in the roller holder 31.
It's getting into b. The dimensions of each of the engagement holes 31a, 31b in the sliding direction of the piston 33 are approximately the same as the dimensions of the a-rad 35.

Therefore, when the piston 33 moves, the roller holder 31 rotates by an amount corresponding to the moving distance. On the other hand, the dimensions of the engagement holes 31a and 31b in the ring direction (reciprocating direction) of the plunger 15 are larger than the dimensions of the rod 35. Therefore, the roller holder 31 is movable relative to the rod 35 and the piston 33 in the ring line direction of the plunger 15.

In the timer mechanism configured as described above, when the pressure of the fuel in the fuel chamber 12 increases as the engine speed increases and the pressing force of the fuel acting on the piston 33 becomes greater than the urging force of the piston 34, the piston 33 moves against the urging force of the spring 34 and stops when the pressing force of the fuel and the urging force of the spring 34 are balanced. The roller holder 31 is rotationally displaced in the direction opposite to the rotational direction of the drive shaft 18 by the distance traveled until it stops. As a result, the fuel injection timing is advanced and a so-called advance angle can be obtained.

Further, in this distribution type fuel injection pump, the following structure is adopted in order to increase the fuel injection amount in the high speed rotation range. That is, as shown in FIGS. 1 to 3, three protrusions (projections) 31c are formed at equal intervals in the circumferential direction on the end surface of the roller holder 31 that contacts the side plate 27. Therefore, the roller holder 31
comes into contact with the side plate 27 via the protrusion 31c. - On the side plate 27, three inclined surfaces 27m extending along the circumferential direction are formed. This inclined surface 27a is separated from the protrusion 31c in the low speed rotation range, but in the high speed rotation range, when the roller holder 31 is rotationally displaced in the direction of increasing the advance angle (in the direction of arrow E in FIG. 1), the protrusion 31c
1c are arranged so as to be in contact with each other. Furthermore, the inclined surface 27e is inclined away from the roller holder 31 in the direction of arrow E).

Therefore, in the above distribution type fuel injection pump,
When the roller holder 31 is rotationally displaced in the direction opposite to the rotational direction of the drive shaft 18 as the engine speed increases,
The protrusion 31c comes into contact with the inclined surface 27c, and the roller holder 31 is moved away from the control sleeve 17 by an amount corresponding to the amount of rotational displacement of the roller holder 31 (
1) in the direction of arrow F in Fig. 1. Following this, the cam plate 19 and the plunger 15 are moved in the same direction by the biasing force of the spring 20. As a result, the timing at which the cutoff port 15c of the plunger 15 is exposed from the control sleeve 17 is delayed. The injection amount is corrected to increase by the amount of the delay.

Here, since the pressure of the fuel in the fuel chamber 12 remains constant unless the engine speed changes, the roller holder 31 also maintains a constant position. Therefore, it is possible to stably and accurately correct the fuel injection amount. Further, no noise is generated.

In the above embodiment, the protrusion 31c is formed on the roller holder 31 and the inclined surface 27a is formed on the side plate 27.
A protrusion may be formed on the surface.

In that case, the direction of inclination of the inclined surface is opposite to that of the inclined surface 27a. In other words, it is tilted away from the side plate 27 in the direction of rotation of the drive shaft 18 .

In any case, when the roller holder 31 is rotationally displaced to increase the advance angle, the roller holder 31 is moved to the cam plate 1.
9 and the plunger 15 in the backward movement direction. Furthermore, the degree of inclination of the inclined surface 27a may not be constant, but may be made to gradually increase in the direction of arrow E in FIG. 1, or conversely to become gradually smaller.

Further, although the protrusion 31c is formed integrally with the roller holder 31, a ball or a roller may be provided on the roller holder 31 so as to be rotatable. In this way, the frictional resistance when opening the roller holder 31 and the side plate 27 can be reduced, and the roller holder 31 can be rotated smoothly.

Furthermore, although the roller holder 31 is brought into contact with the side plate 27 of the feed pump 24, it may be brought into contact with another member.

[Effects of the Invention] As explained above, according to the distribution type fuel injection pump of the present invention, the roller holder is provided so as to be movable in the reciprocating direction of the cam plate, and the mutual contact surfaces of the roller holder and the pressure receiving member are A protrusion is formed on one side of the roller holder, and the protrusion comes into contact with the other when the roller holder rotates as the fuel pressure increases in the fuel chamber, and the roller holder rotates as the fuel pressure increases. Since the roller holder is formed with an inclined surface that is inclined so as to move the roller holder in the backward movement direction of the cam plate according to the direction of Effects such as being able to prevent this can be obtained.

[Brief explanation of the drawing]

1 to 5 show one embodiment of the present invention, in which FIG. 1 is a side view of the main parts, FIG. 2 is a view taken along arrows - ■ in FIG. 4 is a partially omitted sectional view, FIG. 5 is a sectional view taken along V--■ in FIG. FIG. 11... Pump housing, 12... Fuel chamber, 14
...Fuel pressurization chamber, 15...Plunger, 15c...
・Cut-off port, 17... Control sleeve, 18... Drive shaft, 19... Cam plate, 20... Spring (elastic member), 27... Side plate (pressure receiving member), 27a
... Inclined surface, 28 ... Timer mechanism, 31 ... Roller holder, 31c ... Protrusion (protrusion).

Claims (1)

[Claims] A pump housing having a fuel chamber formed therein, a timer mechanism rotatably installed in the fuel chamber of the pump housing and having a roller holder that rotationally displaces according to the pressure of the fuel in the fuel chamber, and a timer mechanism having a fuel chamber at one end. A plunger that pressurizes the fuel in the pressure chamber is provided, and a cam plate whose other end is pressed into contact with the roller holder by the urging force of an elastic member and rotates and reciprocates together with the plunger; a pressure receiving member provided on the pump housing to receive the biasing force of the elastic member acting on the roller holder; and a control sleeve slidably provided on the outer periphery of the plunger; In the distribution type fuel injection pump, the fuel injection is terminated when the opening cut-off port is exposed from the control sleeve, and the roller holder is provided to be movable in the reciprocating direction of the cam plate, and the roller holder is movable in the reciprocating direction of the cam plate. A protrusion is formed on one of the mutual contact surfaces of the holder and the pressure receiving member, and the protrusion comes into contact with the other when the roller holder is rotationally displaced as the pressure of the fuel in the fuel chamber increases; A distribution type fuel injection pump, further comprising an inclined surface that is inclined so as to move the roller holder in the direction of backward movement of the cam plate as the roller holder moves in the direction of rotation as the pressure of the fuel increases. .