JPH0544540Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a prestroke control mechanism for a fuel injection device.

(Prior Art) As a conventional pre-stroke control mechanism for a fuel injection device, there is one disclosed in, for example, Japanese Patent Laid-Open No. 62-91645. This prestroke control mechanism includes a timing sleeve (control sleeve) that adjusts the prestroke position, as shown in Fig. 5.
114 is slidably attached to the plunger 108, and the timing sleeve 114 is slidably attached to the plunger 108.
A timing rod (operating shaft) 126 for vertically moving the plunger 108 can be freely rotated.
The tip of a pin (lever) 128, which is attached perpendicularly to the timing rod 126 and fixed to the timing rod 126 with a lock screw 129, is slidably fitted into a groove (notch groove) 114b of the timing sleeve 114.

The timing rod 126 is provided with a screw hole 126a facing the timing sleeve 114. A lock screw 129 is screwed into the screw hole 126a via a washer 130 in order to fix the pin 128 to the timing rod 126. The outer periphery of the lock screw 129 is threaded and has a through hole 129a into which the rear end of the pin 128 is inserted.

(Problems to be Solved by the Invention) However, when considering the moment of each part of the timing adjustment mechanism with respect to the rotation center of the timing rod, the timing sleeve acts as an unbalanced weight with respect to the rotation center. As a result, when vibrations generated, for example, when the engine operates are transmitted to the fuel injection device, the timing sleeve 114 swings in the axial direction of the plunger, causing a problem in that the prestroke position moves.

The present invention was developed in view of the above circumstances, and is a fuel injection device that can absorb the axial vibration of the timing sleeve caused by vibrations from the engine side and prevent fluctuations in the prestroke position. The purpose of this invention is to provide a pre-stroke control mechanism.

(Means for Solving the Problem) In order to achieve the above-mentioned object, the present invention has a timing sleeve for adjusting a pre-stroke position that is slidably attached to a plunger, and the timing sleeve is moved up and down along the plunger. A timing rod is rotatably attached to the plunger in a direction perpendicular to the plunger, and a tip of a pin fixed to the timing rod with a lock screw is slidably fitted into a groove in the timing sleeve. In the pre-stroke control mechanism of a fuel injection device, the lock screw is configured to
The timing rod is characterized in that it is configured to serve as a balance weight that balances the timing sleeve with respect to the center of rotation.

(Function) Since the lock screw acts as a balance weight that balances the timing sleeve with respect to the center of rotation of the timing rod, the timing sleeve is prevented from swinging in the axial direction due to vibrations generated by the engine.

(Example) An example of the present invention will be described below based on the drawings.

FIG. 1 is an enlarged vertical sectional view showing a prestroke control mechanism of a fuel injection device according to an embodiment of the present invention;
FIG. 2 is a longitudinal sectional view showing a fuel injection device equipped with the prestroke control mechanism.

In the figure, 2 is a housing of a row-type fuel injection device of a diesel engine, 4 is one of a plurality of barrels held within the housing, and each barrel 4
are positioned so that their axes are aligned in parallel on one plane inside the housing 2. 6 is a discharge valve holder attached to the upper part of each barrel 4 and connected to each cylinder of the engine, 7a is a discharge valve, 8 is each barrel 4
A plunger is slidably fitted inside, 10 is a spring that urges the plunger downward, 12 is a cam that is linked to the drive shaft of an engine (not shown) and pushes up the plunger 8, and 14 is slidable on the outer periphery of the plunger 8. Timing sleeve fitted into 1
6 is fixed to each barrel 4 and has a timing sleeve 1
A guide pin 18 that engages with the guide groove 17 of the barrel 4 to restrict its rotation is a sleeve that is rotatably supported by the barrel 4 and non-rotatably engaged with the plunger 8. The plunger 8 has an oil passage 8a that communicates between the upper end surface and the circumferential side, a circumferential side opening 8b that communicates with the oil passage 8a and is formed on the circumferential side, and a vertical groove 8c that runs along the plunger axis. The grooves 8c, 8 have inclined grooves 8d.
d and the circumferential side opening 8b (hereinafter referred to as opening) form a control groove. On the other hand, timing sleeve 1
4 is provided with a control hole 14a that defines the end of injection.

Reference numeral 15 indicates a fuel chamber that stores fuel supplied from a feed pump (not shown), and the fuel does not leak into the camshaft chamber 13 because the plunger 8 is fitted into the barrel 4 in an oil-tight state.
Further, 21 is an oil supply port for supplying lubricating oil into the camshaft chamber 13, and 23 is a guide pin protruding from the tappet 25, which is slidably engaged with a guide groove 27 carved in the housing 2. do. 26 is a timing rod 26 for moving the timing sleeve 14 up and down along the plunger 8;
It is rotatably attached to the plunger 8 in a direction perpendicular to it. As shown in FIG. 3, the timing rod 26 is provided with screw holes 26a facing each of the timing sleeves 14, respectively. A lock screw 29 is screwed into the screw hole 26a via a washer 30 in order to fix the pin 28 to the timing rod 26. A thread 29b is cut on the outer periphery of one end of the lock screw 29.
The other end is greatly bulged.

The lock screw 29 has a through hole 29a into which a part of the pin 28 is inserted, and a thread is cut on the outer periphery of one end of the lock screw 29, and the other end is greatly bulged, making it lighter in weight than conventional lock screws. It has increased. The weight position and mass of the lock screw 29 are set so that the lock screw 29 serves as a balance weight that balances the timing sleeve 14 with respect to the center of rotation of the timing rod 26. The tip of the pin 28 fixed to the timing rod 26 by a lock screw 29 is slidably fitted into a groove 14b provided in the timing sleeve 14. Therefore, the pin 28 transmits the rotational movement of the timing rod 26 to the timing sleeve 14, and the timing sleeve 14 moves up and down along the plunger 8. Note that the outer circumferential surface of the tip of the pin 28 has a curvature that constantly contacts the inner circumferential surface of the groove 14b to prevent play.

Furthermore, in the above configuration, the cam 1
2 rotates once, the roller 25a of the tappet 25
Each time the plunger 8 is pressed by the cam 12, the plunger 8 is reciprocated upward by a fixed lift amount, that is, by one stroke up and down.

Here, the process of pumping fuel by the plunger 8 being pressed by the cam 12 will be explained with reference to FIGS. 4a to 4d (timing sleeve 14 is assumed to be in the fixed position). When the position is shown in figure a, that is, when the opening 8b is not completely closed by the timing sleeve 14, the pressurizing chamber 20
Since the fuel chamber 15 and the fuel chamber 15 are in communication with each other, fuel is not pumped. Next, when the opening 8b passes through the state shown in b and is closed by the timing sleeve 14 as shown in FIG. This a~
The stroke of the plunger 8 through the distance c is called a prestroke. c Plunger 8 as shown in the figure.
When the pressure rises, the discharge pressure in the pressurizing chamber 20 overcomes the spring force of the spring 7b of the discharge valve holder 6, opening the discharge valve 7a, and high-pressure fuel is supplied to an injection nozzle (not shown) via the injection pipe 7a. . The fuel is fed under pressure until the inclined groove 8b of the plunger communicates with the control hole 14a as shown in figure d, but when the inclined groove 8d comes to face the control hole 14a as shown in figure d, the pressurizing chamber 20 It communicates with the fuel chamber 15 via the oil passage 8a, the opening 8b, and the groove 8c, and the pressure feeding ends. Further, since the inclined groove 8d extends on the outer periphery of the plunger 8 at an angle with respect to its axis, by rotationally displacing the plunger 8 by the sleeve 18, the inclined groove 8d and the control sleeve 14 can be connected to each other during the stroke of the plunger 8. The timing of correspondence with the opening 14a can be changed, thereby allowing the plunger 8 to
The amount of injection per stroke can be adjusted. Incidentally, the rotational displacement of the sleeve 18 is carried out by displacing the rack 24, which engages with a ball 22 fixed on the sleeve 18, in its longitudinal direction.

When an actuator (not shown) operates and the timing rod 26 rotates counterclockwise, the timing sleeve 14 slides downward (towards the cam 12) along the plunger 8 by the pin 28 fixed to the timing rod 26. As a result, the prestroke position changes to the small side, and the injection timing becomes earlier. On the other hand, when the timing rod 26 rotates clockwise, the timing sleeve 14 slides upward (toward the discharge valve holder 6 side) along the plunger 8, and the prestroke position changes to the large side, causing the injection timing to change. is delayed.

Further, according to the above embodiment, the lock screw 29 serves as a balance weight that balances the timing sleeve 14 with respect to the rotation center of the timing rod 26, so that the timing sleeve 14 is moved in the axial direction of the plunger 8 due to vibrations caused by, for example, the engine. This prevents the camera from swinging. This prevents the timing rod 26 from twisting and the prestroke position from changing.

(Effect of the invention) As explained above, according to the pre-stroke control mechanism of the fuel injection device of the invention, the lock screw acts as a balance weight that balances the timing sleeve with respect to the center of rotation of the timing rod. This prevents the timing sleeve from swinging in the axial direction due to vibration.
Therefore, the timing rod does not twist, the prestroke position does not change, and controllability is not impaired.

Additionally, since the number of parts does not increase and the assembly and adjustment processes do not change, fluctuations in the prestroke position can be prevented without increasing costs, and assembly and adjustment can be performed using conventional and familiar work methods. can.

[Brief explanation of drawings]

FIG. 1 is an enlarged vertical cross-sectional view showing a pre-stroke control mechanism according to an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view showing a fuel injection mechanism equipped with the pre-stroke control mechanism, and FIG. 4A to 4D are diagrams for explaining the relationship between the plunger and the timing sleeve, and FIG. 5 is an enlarged longitudinal sectional view showing the conventional prestroke control mechanism. 8... Plunger, 14... Timing sleeve, 14b... Groove, 26... Timing rod,
28...Pin, 29...Rock Screw.

Claims (1)

[Scope of utility model registration request] A timing sleeve that adjusts the prestroke position is slidably attached to the plunger.
A timing rod for moving the timing sleeve up and down along the plunger is rotatably attached to the plunger in a direction perpendicular to the plunger, and the tip of a pin fixed to the timing rod with a lock screw is attached to the timing rod. In a pre-stroke control mechanism of a fuel injection device that is slidably fitted into a groove of a sleeve, the lock screw is configured to serve as a balance weight that balances the timing sleeve with respect to the center of rotation of the timing rod. A pre-stroke control mechanism for a fuel injection device characterized by: