JPH0541246Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for adjusting the injection timing of a bottle-type fuel injection pump installed in a fuel injection system of a diesel engine.

[Prior Art] A bottle-type fuel injection pump installed in the fuel injection system of a diesel engine, for example, as shown in FIG. 7, rotates a plunger d in a plunger barrel c inserted into a hole b in a pump body a. The fuel in the pressurizing chamber i is pressurized by vertically moving the plunger d with a cam g fixed to the camshaft f via the tappet e to open and close the fuel inlet h. The fuel is fed under pressure from the delivery valve j to the fuel supply pipe.

[Problem that the invention attempts to solve]

In such a fuel injection pump, the camshaft f is connected to the engine crankshaft via a timing gear, and the camshaft f always rotates in synchronization with the crankshaft, so the timing at which the plunger d is raised by the cam g is determined by the crankshaft. Since the injection timing is always constant with respect to the rotation of the shaft g, the injection timing is also always constant, which may cause an injection delay or a drop in injection pressure at low speed rotation. The injection timing can be controlled by connecting the cams or by allowing the cam to rotate relative to the camshaft.

However, controlling the injection timing as described above requires a very complicated structure.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an injection timing adjustment device for a fuel injection pump that can control injection timing with a simple structure.

[Means and actions for solving the problem] A bottle-type fuel injection pump that raises the plunger 4 using a cam 7 provided on the camshaft 6 to close the fuel inlet 8 and pressurizes and pumps the fuel in the pressurizing chamber 9. In this case, the plunger 4 is connected to a projection 2 having a flat surface 22.
3, a lower plunger 21 having a blind hole 24 and a notch 25 in which the protrusion 23 is slidably and non-rotatably fitted; It consists of a press-fit pin 26 inserted into the blind hole 24 of the plunger 21 and a spring 30. The press-fit pin 26 is inserted into the blind hole 24, and the spring 30 is provided to force the protrusion 23 to fit into the notch 25, and the upper plunger 20 and the lower plunger 21
A pin 26 is press-fitted into the blind hole 24 of the lower plunger 21 so as to be slidable in the longitudinal direction but not rotatable.
This injection timing adjustment device for a bottle-type fuel injection pump is configured with an oil chamber 31 that pushes up the oil chamber 31, and is configured to supply control pressure to the oil chamber 31.

As a result, when the control pressure is not supplied to the oil chamber 31, the upper plunger 20 is pushed down by the spring 30 and comes into contact with the lower plunger 21, so that the length of the plunger 4 is minimized, and when the control pressure is supplied to the oil chamber 31, the upper plunger 20 20 moves upward with respect to the lower plunger 21, and the length of the plunger 4 becomes longer. Therefore, the injection timing can be adjusted by changing the stroke that closes the fuel inlet, and the pressure of the control pressure supplied to the oil chamber 31 can be adjusted. By making the adjustment, the injection timing can be adjusted, and since the amount of upward movement of the upper plunger 21 can be accurately determined by the control pressure of the oil chamber 31, the injection timing can be adjusted with high precision.

In addition, the plunger 20 and the lower plunger 2
1 does not rotate relative to each other due to the fitting portion between the protrusion 23 and the notch 25, so the upper plunger 20 can be rotated together with the lower plunger 21, so the injection amount can be increased or decreased in the same way as in the past, and the upper plunger 2
0 toward the lower plunger 21 is provided in the blind hole 24 of the lower plunger 21 and does not protrude from the outer peripheral surface of the plunger 4.
The plunger 4 can be smoothly slid up and down without getting in the way when the plunger 4 slides up and down.

〔Example〕

The plunger barrel 3 is inserted into the hole 2 of the pump body 1, and the plunger 4 is inserted into the plunger barrel 3, and the plunger 4 is inserted into the tappet 5.
The cam 7 is fixed to the camshaft 6 through the cam 7, which moves up and down.
The fuel inlet 8 is closed to pressurize the fuel in the pressurizing chamber 9 and forcefully send it to the fuel supply pipe 11 from the delivery valve 10. The control rack 14 is engaged, and the control sleeve 12 is fitted onto the plunger 4 so as to be non-rotatable.

The plunger 4 consists of an upper plunger 20 and a lower plunger 21, and the upper plunger 20
A protrusion 23 having a flat surface 22 is integrally formed on the
The lower plunger 21 is formed with a notch 25 into which the blind hole 24 and the projection 23 fit, and the two are fitted and connected so that they cannot rotate relative to each other, and one end of the press-fit pin 26 is press-fitted into the projection 23 of the upper plunger 20. A press-fit sheet 27 is fixed to the press-fit pin 26.
The upper and lower spring seats 28, 29 and the spring 30 are installed, and the press-fit seat 27 is tightly fitted into the blind hole 24 as shown in FIG.
The press-fit pin 26 is pulled and the upper plunger 20
and the lower plunger 21 are joined to form the press-fit seat 2.
7 is positioned in a predetermined position, and the blind hole 24
The press-fit pin 26 and the lower spring seat 29 constitute an oil chamber 31, which opens outward from the joint and is controlled by a port 32 formed in the plunger barrel 3, as shown in FIG. Pressure oil is supplied.

Therefore, when control pressure oil is supplied to the oil chamber 31 from the port 32, the upper plunger 20 is pushed upward against the spring 30, and the fuel inlet 8 and the upper part 4 of the plunger 4 are moved upwardly against the spring 30, as shown in FIG. Since the distance l (pre-stroke) from the cam 6 changes, the timing at which the fuel inlet 8 is closed when the plunger 4 is pushed up by the cam 6 to pressurize and inject the fuel in the pressurizing chamber 9, that is, the injection timing, is adjusted. can.

In addition, the lower two surface portions 21a of the lower plunger 21
Since the control sleeve 12 is fitted in the control rack 14, the lower plunger 21 is rotated by rotating the control sleeve 12 with the control rack 14, whereby the notch 25 and the protrusion 2 are rotated.
2, the upper plunger 20 rotates to increase or decrease the injection amount.

[Effect of the invention] When the control pressure is not supplied to the oil chamber 31, the upper plunger 20 is pushed down by the spring 30 and comes into contact with the lower plunger 21, so that the length of the plunger 4 is minimized, and when the control pressure is supplied to the oil chamber 31. Since the upper plunger 20 moves upward relative to the lower plunger 21 and the length of the plunger 4 becomes longer, the injection timing can be adjusted by changing the stroke that closes the fuel inlet.

Therefore, the injection timing can be adjusted by adjusting the pressure of the control pressure supplied to the oil chamber 31, and the amount of upward movement of the upper plunger 21 can be accurately determined by the control pressure of the oil chamber 31. Injection timing can be adjusted with high precision.

In addition, the upper plunger 20 and the lower plunger 2
1 does not rotate relative to each other due to the fitting portion between the protrusion 23 and the notch 25, so the upper plunger 20 can be rotated together with the lower plunger 21, so that the injection amount can be increased or decreased in the same manner as in the conventional case.

Also, the upper plunger 20 is replaced with the lower plunger 2.
The spring 30 biasing the lower plunger 21 toward the first side is provided in the blind hole 24 of the lower plunger 21 and does not protrude from the outer circumferential surface of the plunger 4, so it can move the plunger 4 without getting in the way when the plunger 4 slides up and down. Can slide up and down smoothly.

[Brief explanation of the drawing]

Figures 1 to 6 show embodiments of the present invention;
The figure is a sectional view of the plunger, the second figure is an exploded perspective view,
3 and 4 are a front view and a side view, FIG. 5 is a general sectional view, FIG. 6 is an explanatory diagram of the operation, and FIG. 7 is a sectional view of a conventional example. 4 is a plunger, 6 is a camshaft, 7 is a cam, 8 is a fuel inlet, 9 is a pressurizing chamber, 20 is an upper plunger,
21 is the lower plunger, 31 is the oil chamber.

Claims (1)

[Scope of Claim for Utility Model Registration] A bottle-type fuel injection pump in which a cam 7 provided on a camshaft 6 raises a plunger 4 to close a fuel inlet 8 to pressurize and force-feed fuel in a pressurizing chamber 9, comprising: 4, a protrusion 2 having a flat surface 22
3, a lower plunger 21 having a blind hole 24 and a notch 25 in which the protrusion 23 is slidably and non-rotatably fitted; It consists of a press-fit pin 26 inserted into the blind hole 24 of the plunger 21 and a spring 30. The press-fit pin 26 is inserted into the blind hole 24, and the spring 30 is provided to force the protrusion 23 to fit into the notch 25, and the upper plunger 20 and the lower plunger 21
A pin 26 is press-fitted into the blind hole 24 of the lower plunger 21 so as to be slidable in the longitudinal direction but not rotatable.
An injection timing adjustment device for a bottle-type fuel injection pump, characterized in that the oil chamber 31 is configured to push up the oil chamber 31, and control pressure is supplied to the oil chamber 31.