JPH03233144A - Prestroke control device of fuel injection pump - Google Patents

Abstract

PURPOSE:To make fuel injection timing controllable in accordance with a rotational speed of an engine and request of its operation by using a fly weight to turn-control a timing control rod so that the characteristic of turning of this rod can be selected by a timing cam. CONSTITUTION:A degree of turning of a timing control rod 22 can be controlled by moving a fly weight 43 to a position in accordance with a rotational condition of an engine, turning a prestroke control lever 44 in accordance with movement of this fly weight and changing a relative position between a timing controlling cam surface 47A of a timing cam 47, connected to this lever 44, and the timing control rod 22. Accordingly, a prestroke of a plunger 5, that is, timing of fuel injection can be controlled by turning the rod 22 by a predetermined angle in accordance with the rotational condition of the engine, and also the prestroke characteristic, containing a start advancing timing, can be freely selected by suitably designing the cam surface 47A of the timing cam 47.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pre-stroke control device for a fuel injection pump used in an internal combustion engine such as a diesel engine, and in particular, the present invention relates to a pre-stroke control device for a fuel injection pump used in an internal combustion engine such as a diesel engine. The present invention relates to a prestroke control device for a fuel injection pump that variably controls the prestroke.

[Prior Art] Conventionally, some fuel injection pumps have been equipped with a variable prestroke mechanism to vary the prestroke, and generally this mechanism consists of a control sleeve fitted over a plunger that reciprocates up and down. The prestroke is made variable by adjusting the relative positional relationship between the two.

However, this variable mechanism is electronically controlled (for example, Japanese Patent Application Laid-Open No. 83-105274). Furthermore, since a large number of various parts such as wire harnesses are required, it is difficult to ensure reliability and it is difficult to keep costs low.

A general structure of a fuel injection pump having a variable prestroke mechanism will be explained based on FIG. 9.

FIG. 9 is a longitudinal sectional view of the fuel injection pump 1, in which the pump housing 2 is formed with vertical holes 3 in a number corresponding to the number of cylinders of the engine, and the lower plunger barrel 4 is inserted into the vertical holes 3. It is inserted and fixed into the pump housing 2, and the plunger 5 is inserted into the lower plunger barrel 4 so as to be rotatable and reciprocatable.

The upper end of the plunger 5 is inserted through the lower plunger barrel 4 into an upper plunger barrel 6 fixed to the pump housing 2 . This upper plunger barrel 6
A delivery valve 7 is provided inside, a fuel pressure chamber 8 is formed between the delivery valve 7 and the plunger 5, and a fuel outlet 9 is formed above the delivery valve 7.

Further, the lower end of the plunger 5 is in contact with a cam 11 provided on a camshaft IO via a tappet 12. This camshaft 10 is connected to an engine, is rotationally driven by the engine, and is driven by a spring 1.
The plunger 5 is brought into contact with the cam 11 along the periphery of the cam 11 in cooperation with the cam 3, and the plunger 5 is caused to reciprocate in the vertical direction in the figure.

Furthermore, this plunger 5 has a driving face 1.
4, and this driving face 14 is engaged with an injection amount adjusting sleeve 15. Further, the projection 16 is engaged with the injection amount adjusting sleeve 15, and the projection 16 is engaged with the sleeve 15 for adjusting the injection amount.
Press the injection amount adjustment rod 17 engaged with the accelerator pedal (
The injection amount adjusting sleeve 15 can rotate the plunger 5 by driving in a direction perpendicular to the plane of the paper according to the amount of depression (not shown). That is, the effective stroke of pressure feeding for fuel injection can be adjusted by rotating the plunger 5 using the injection amount adjusting rod 17.

Further, in the upper part of the plunger 5, a control sleeve 18 is provided.
It is slidably fitted on the outside. The control sleeve 18 is formed with a vertical guide groove 19 on the left side in the figure and a horizontal engagement groove 20 on the right side in the figure. A guide pin 21 provided on the lower plunger barrel 4 is engaged with the guide groove 19, and a timing control rod 2 is engaged with the engagement groove 20.
In this case, the second engaging portion 23 is inserted.

The timing control rod 22 is inserted into a horizontal hole 24 formed in the pump housing 2, and is rotatably supported by the pump housing 2 via a bearing (not shown). In the case of electronic control systems,
This timing control rod 22 is connected to a seven actuator (not shown) such as a step motor, and is driven to rotate by this actuator.

Note that the prestroke can be adjusted by moving the control sleeve 18 up and down by such rotation of the timing control rod 22. That is, timing control rod 2
2 in the forward and reverse directions as shown by the arrows in the figure, the retaining portion 23 rotates together with the timing control rod 22, and the rotation of the engaging portion 23 causes the control sleeve 18 to move up and down. The relative positions of the plunger 5 and the control sleeve 18 in the vertical direction change.

Therefore, the pre-stroke of the plunger 5 defined as the dimension between the control sleeve 18 and the position of the fuel intake/discharge hole 26 (described later) at the bottom dead center of the plunger 5 can be adjusted.

In other words, the dimension from the bottom dead center of the plunger 5 to when the fuel intake/discharge hole 26 is closed is the prestroke of the plunger 5, and when the fuel intake/discharge hole 26 is closed, fuel injection begins.

Specifically, when the timing control rod 22 is rotated clockwise to move the control sleeve 18 upward, the prestroke becomes larger and the injection start timing is delayed, so that the engine speed is moved to a low speed range where the engine speed is low. Adapted high injection rate (ratio of fuel injection amount to unit rotation angle of the camshaft lO, that is, rate of change in injection amount over time)
By obtaining this, it is possible to improve the atomization characteristics of fuel into the combustion chamber of the engine when the temperature is relatively low.

Conversely, when the timing control rod 22 is rotated counterclockwise to move the control sleeve 18 downward, the prestroke becomes smaller and the injection timing becomes earlier, resulting in a lower injection rate suitable for the high speed rotation range. Obtainable. However, the absolute amount of injection increases.

Furthermore, the plunger 5 slidably inserted into the lower plunger barrel 4 receives rotational driving force from an engine (not shown) via the camshaft 10 and the cam 11, thereby causing the lower plunger barrel 4 and the upper upper plunger to It reciprocates within the barrel 6, sucks the fuel in the fuel reservoir chamber 25 into the fuel pressure chamber 8, and further pumps the fuel in the fuel pressure chamber 8 from the fuel outlet 9 through an injection pipe (not shown). The liquid is then injected from an injection nozzle (not shown).

That is, this plunger 5 has a radial fuel intake/discharge hole 26 which is a fuel intake port opening into the fuel reservoir chamber 25.
, a communication hole 27 formed in the central axis direction so as to communicate the fuel intake/discharge hole 26 and the fuel pressure chamber 8, a control inclined groove 28 formed on the outer surface of the communication hole 27, and a control inclined groove 28 formed on the outer surface of the communication hole 27.
and a vertical communication groove 2 that communicates the opening of the fuel intake and exhaust hole 26.
9.

Furthermore, the control sleeve 18, which is slidably fitted onto the plunger 5, has a cut-off hole 30 in its radial direction.
It is formed through. The cutoff hole 30 is arranged in a vertical positional relationship such that it can communicate with the control inclined groove 28 according to the movement of the plunger 5 in the vertical direction.

The fuel reservoir chamber 25 communicates with the fuel inlet 31 through the horizontal hole 24 formed in the pump housing 2.

The operation of the fuel injection pump 1 configured as above will be explained.

First, when the plunger 5 initially rises from the bottom dead center, the fuel intake/discharge hole 26 opens into the fuel reservoir chamber 25, and the fuel reservoir chamber 25 and the fuel pressure chamber 8 are connected to the fuel intake/discharge hole 26 and the communication hole 27. , the pressure of the fuel in the fuel pressure chamber 8 does not increase, and the delivery valve 7 remains closed.

When actually delivering fuel, the plunger 5 rises and its fuel intake/discharge hole 26 is closed by the control sleeve 18, thereby increasing the pressure of the fuel in the fuel pressure chamber 8, opening the delivery valve 7, and opening the fuel outlet 9. Fuel is delivered from the engine, and injection (pressure feeding of fuel) is started.

When the plunger 5 further rises and the control inclined groove 28 communicating with the fuel intake/discharge hole 26 communicates with the cutoff hole 30 of the control sleeve 18, the cutoff hole 30, the control inclined groove 28, and the communication longitudinal groove 29 , the cut-off hole 30 and the fuel pressure chamber 8 communicate with each other through the fuel intake/discharge hole 26 and the communication hole 27, so that the fuel in the fuel pressure chamber 8 escapes to the fuel reservoir chamber 25, and the fuel in the fuel pressure chamber 8 The pressure decreases, the delivery valve 7 is closed, and the injection (pressure feeding of fuel) is completed.

Then, when the plunger 5 descends, the fuel reservoir chamber 2
5 into the fuel pressure chamber 8 due to the negative pressure of the fuel.

Furthermore, by rotating the timing control rod 22, the control sleeve 18 can be moved up and down to control the prestroke, that is, the timing of fuel injection. Between electronics'a for rotation control
If this mechanism is adopted, there are problems in terms of reliability and cost.

In order to control the injection timing, there is a Japanese Utility Model Application No. 63-198443 that uses a flyweight that moves according to the engine speed, but in this case, the control sleeve is moved up and down as the flyweight moves. There is a problem that the degree of freedom of control is small.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, the present invention uses a mechanical mechanism to rotate the timing control rod, instead of using an electronic mechanism as in the past, thereby adjusting the rotational state of the engine. This makes it possible to reliably vary the prestroke according to the engine operating conditions, making it possible to realize a fuel injection timing control mechanism at low cost, and increasing the degree of freedom in controlling the injection timing according to the demands of engine operation. An object of the present invention is to provide a prestroke control device for a fuel injection pump that can control the prestroke of a fuel injection pump.

[Means for Solving the Problems] That is, the present invention includes a plunger barrel having a fuel pressure chamber, a camshaft connected to an engine, and a fuel reservoir that moves reciprocally within the plunger barrel according to the rotation of the camshaft. A plunger that sucks fuel from a chamber and pumps the fuel, a control sleeve that is slidably fitted onto the plunger, and a timing control rod that is connected to the control sleeve, and the timing control rod is rotated. A pre-stroke control device for a fuel injection pump, which adjusts a pre-stroke by changing the relative position of the plunger and the control sleeve in the axial direction, the fly weight moving according to the rotation of the camshaft; A prestroke control lever that rotates according to the movement of the flyweight,
In addition to being connected to this prestroke control lever,
The pre-stroke control device for a fuel injection pump is characterized in that it has a timing cam formed with a cam surface for timing control that can be interlocked with the timing control rod.

Note that a conventional mechanical governor may be used as the flyweight, or it may be provided separately.

Further, as the pre-stroke control lever, a tension lever in a conventional mechanical governor can be used, or a pre-stroke lever of any shape such as an L-shape can also be used.

[Operation 1] In the prestroke control device for a fuel injection pump according to the present invention, the flyweight moves to a position corresponding to the rotational state of the engine, and with this movement, the prestroke control lever rotates. The relative position between the timing control cam surface of the timing cam connected to the prestroke control lever and the timing control rod changes, so that the degree of rotation of the timing control rod can be controlled.

Therefore, by rotating the timing control rod by a predetermined angle depending on the rotational state of the engine, it is possible to control the pre-stroke of the plunger, that is, the timing of fuel injection, and by appropriately designing the cam surface of the timing cam. The prestroke characteristics, including the starting advance angle, can be freely selected, and arbitrary timing control can be performed.

[Embodiment] Next, a pre-stroke control device 40 for a fuel injection pump according to a first embodiment of the present invention will be explained based on FIGS. 1 to 4, and also FIGS. 7 and 8. however,
In the following description, the same parts as in FIG. 9 are denoted by the same reference numerals, and detailed description thereof will be omitted. Note that this prestroke control device 40 is configured in combination with a conventional mechanical governor 41.

FIG. 1 is a perspective view of the main parts of the prestroke control device 40, FIG. 2 is a view taken in the direction of arrow ``■'' in FIG. 1, and FIG.
It is a directional view.

As shown in FIG. 1, a guide sleeve 42 and a flyweight 43 connected to the guide sleeve 42 are attached to the camshaft IO. Guide sleeve 42
A lower end portion of a tension lever 44 as a pre-stroke control lever is rotatably connected to the lower end portion of the tension lever 44 .

The tension lever 44 rotates or swings around a rotating fixed shaft 45, and a timing cam 47 is connected to one end thereof via a connecting lever 46.

Note that the torque cam 48 of the mechanical governor 41 is connected to the other tip of the tension lever 44 to constitute a predetermined governor mechanism that automatically adjusts the fuel injection amount according to fluctuations in the load on one engine. A description of this configuration will be omitted.

The timing cam 47 is rotatable around a fixed rotating shaft 49, and has a cam surface 47A for timing control formed on its circumferential surface.

A counterweight 50 is attached to the end of the timing control load 22. A cam surface abutting piece 51 is integrally formed on this counterweight 50 along the axial direction of the timing control rod 22. The cam surface contacting end 51A of the cam surface contacting piece 51 contacts the cam surface 47A for timing control of the timing cam 47 with a predetermined pressing force due to the biasing force of the counterweight spring 52.

Note that an abutting roller may be used instead of the cam surface abutting end 51A.

Since the rotational axis of the cam surface abutting piece 51 and the rotational axis of the timing control rod 22 match, a rotational change of the cam surface abutting piece 51 is immediately recognized as a rotational change of the timing control rod 22. This can be communicated. In addition, by locating the abutting portions of each other near the rotating fixed shaft 49 of the timing cam 47, the governor control of the mechanical governor 41 is not affected.

As shown in FIG. 2, the timing control rod 22 is rotatably supported by the pump housing 2 by a pawl bearing 53 and an oil seal 54.

The operation of the prestroke control device 40 configured as above will be explained.

As shown in FIG. 4, as the engine speed increases, the flyweight 43 is lifted by centrifugal force, and the guide sleeve 42 moves to the right in FIG. 1 along the axial direction of the camshaft IO. Therefore, the tension lever 44 rotates around the rotation fixed shaft 45, and the mechanical lever
The governor 41 performs a predetermined governor function and connects/
The timing cam 47 connects to the rotating fixed shaft 4 via <-46.
Rotate around 9.

As the timing cam 47 rotates, the contact position between the timing control cam surface 47A and the cam surface contact end 51A of the cam surface contact piece 51 changes, and the cam surface contact piece 51
1 or counterweight 50 rotate about the axis of the timing control rod 22 as a rotation axis.

Therefore, the timing control rod 22 also rotates by a predetermined angle, and by moving the control sleeve 18 up and down as described above, the control sleeve 18
By changing the relative positional relationship between the plunger 5 and the plunger 5, it is possible to change the timing of fuel injection, that is, the prestroke.

Thus, by appropriately designing the cam surface 47A for timing control of the timing cam 47, arbitrary timing changes can be realized.

For example, in the example shown in FIG. 2, the end of the cam surface 47A for timing control is made to protrude so that the injection timing can be advanced at the time of starting. In addition, in the low speed rotation range, the cam surface contact piece 51, that is, the counterweight 50 and the timing control rod 22 are
The recess is designed to rotate counterclockwise in the figure. Furthermore, it is formed so that it protrudes again in the high speed range, that is, in the rated rotation range. Therefore, as shown in FIGS. 7 and 8, the prestroke and injection timing can be set arbitrarily in accordance with the engine speed.

Moreover, in this first embodiment, the existing mechanical governor 41 is used as is, and the prestroke control device 40 is added thereto, so that the number of parts can be reduced and the construction can be made at low cost.

Next, a prestroke control device 60 according to a second embodiment of the present invention will be explained based on FIGS. 5 and 6.

The prestroke control device 40 according to the first embodiment described above is an example in which the prestroke control device 40 is incorporated into a known mechanical governor 41, but this prestroke control device 16
0 means that this is provided independently of the mechanical governor 41.

FIG. 5 is a vertical sectional view of the prestroke control device 60, and FIG.
The figure is a view taken in the direction of the ■ arrow in FIG. 5.

As shown in FIG. 5, a rotating shaft 63 is connected to the camshaft 10 via a first gear 61 and a second gear 62.
Concatenate. A sleeve 64 is attached to this rotating shaft 63, and a flyweight 66 is attached to the rotating shaft 65.
Attach.

An L-shaped pre-stroke lever 67 is arranged as a pre-stroke control lever so as to come into contact with the sleeve 64, and is rotatable around a fixed shaft 68 for rotation. Note that this prestroke lever 67 is always urged to rotate clockwise by a lever spring 69.

A timing cam 70 corresponding to the timing cam 47 is integrally formed at the other end of the prestroke lever 67, and a cam surface 70A for timing control is formed on the circumferential surface of the timing cam 70.
form.

On the other hand, a counterweight 50 and a cam surface contact piece 71 corresponding to the cam surface contact piece 51 are attached to the end of the timing control rod 22, and a contact piece spring 7
2, the cam surface contacting end 71A is brought into contact with the cam surface 70A for timing control with a predetermined pressing force.

Similarly to the prestroke control device 40 described above, the prestroke control device 60 having such a configuration can also control the prestroke and adjust the fuel injection timing according to the rotational state of the engine.

That is, when the camshaft lO rotates, the flyweight 66 rotates to spread out according to the rotation speed, and the rotary shaft 63 presses the sleeve 64 to the right in FIG. Fixed shaft for rotation 68
Rotate counterclockwise around the

With this rotation, the contact position between the timing control cam surface 70A of the timing cam 70 and the cam surface contact end 71A of the cam surface contact piece 71 changes, and the cam surface contact piece 71 and the timing control By rotating the rod 22, the relative position of the control sleeve 18 and plunger 5 can be adjusted. Specifically, in FIG. 5, when the cam surface abutting piece 71 rotates counterclockwise, the prestroke increases, and when it rotates clockwise, it decreases.

Thus, as shown in FIGS. 7 and 8, the prestroke and injection timing can be controlled according to the rotational speed.

[Effects of the Invention] As explained above, according to the present invention, a flyweight is used to control the rotation of the timing control rod, and the characteristics of this rotation are controlled by a timing cam having a cam surface for timing control. Since it is selectable,
It is possible to control the fuel injection timing by changing the prestroke according to the engine speed and operating requirements, and since it is a mechanical configuration, it can be configured at a lower cost and more reliably than electronic control. It is.

[Brief explanation of drawings]

FIG. 1 shows a fuel injection pump l according to a first embodiment of the present invention.
FIG. 2 is a perspective view of the main parts of the prestroke control device 40 of FIG. A graph showing the relationship between the rotation speed and the lift of the flyweights 43. FIG. 5 is a longitudinal sectional view of a prestroke control device 60 according to a second embodiment of the present invention. FIG. Figure 7 is a graph showing the relationship between engine speed and prestroke, Figure 8 is a graph showing the relationship between engine speed and injection timing, and Figure 9 is a graph showing the relationship between engine speed and injection timing. FIG. , fuel injection pump, pump body, vertical hole, lower plunger barrel, plunger, upper plunger barrel, delivery valve, fuel pressure chamber 0 1 2 3 4 5 6 7 8 9 0 1 2 3 , fuel outlet, camshaft 0. Cam 9. Tappet 0. Spring, driving face, injection amount adjustment sleeve, protrusion, injection amount adjustment rod, control sleeve 6. Guide groove 0. Engagement groove, guide pin, timing control rod Engagement portion 24 of timing control rod 7 and rod 22. 25. 26. 27. , side hole, fuel reservoir chamber, fuel intake/discharge hole (fuel intake boat), communication hole 8 9 0 1 0 1 2 3 4 45 . 46. 47. 47 A. 48. 49. 50゜51゜51A. 52. , control inclined groove 9. Communication vertical groove, cut-off hole, fuel inlet, pre-stroke control device 0. Mechanical governor, guide sleeve 0. Fly weight 0. Tension lever (pre-stroke control lever), fixed shaft for rotation, connection lever, timing cam9. Cam surface for timing control, torque cam, fixed shaft for rotation9. Counterweight, cam surface contact piece9. Cam surface contact end, counterweight spring 3 4 0 1 2 3 4 5 6 7 0. Pole bearing, oil seal 0. Prestroke control device 0. First gear 0. Second gear 06 rotation shaft, sleeve 00 rotation axis 0. Fly weight 0. L-shaped pre-stroke lever (lever for pre-stroke control) 06 Fixed shaft for rotation 1. Lever spring, timing cam, cam surface for timing control, cam surface contact piece 010. Cam surface contact end 0. Contact piece spring

Claims (1)

[Scope of Claims] A plunger barrel having a fuel pressure chamber; a camshaft connected to an engine; and a camshaft that reciprocates within the plunger barrel according to the rotation of the camshaft to draw fuel from a fuel reservoir chamber and collect the fuel. It has a plunger for pressure feeding, a control sleeve slidably fitted onto the plunger, and a timing control rod connected to the control sleeve, and by rotating the timing control rod, the plunger and the control sleeve are connected. A prestroke control device for a fuel injection pump that adjusts a prestroke by changing a relative position in an axial direction, the device comprising: a flyweight that moves in accordance with the rotation of the camshaft; and a flyweight that moves in accordance with the movement of the flyweight. A rotating pre-stroke control lever, connected to this pre-stroke control lever,
A pre-stroke control device for a fuel injection pump, characterized in that the timing control rod has a timing cam formed with a cam surface for timing control that can be interlocked with each other.