JPS5936672Y2 - Timer of fuel injection pump for internal combustion engine - Google Patents

Description

[Detailed description of the invention] The advance characteristic of the timer of the conventional distributed fuel injection pump for internal combustion engines is one that advances linearly according to the fuel pressure, or linearly as shown in Japanese Utility Model Application No. 54-61127. The lead angle was changed only in the middle part of the lead angle characteristics.

Therefore, it was not possible to control the advance angle characteristic in a polygonal manner in order to match the requirements of the engine.

In order to eliminate the above-mentioned disadvantages, this invention makes it possible to arbitrarily control the advance angle characteristic by controlling the fuel pressure in the chamber in which the timer spring is arranged.

Next, the present invention will be explained according to the drawings.

As shown in FIG. 1, the conventional injection timing adjustment device for an injection pump is driven in relation to the engine rotation speed, and the pumping pressure is pressurized by a feed pump (not shown) that changes depending on the engine rotation speed, and the fuel injection timing is increased. The fuel oil supplied into the pump chamber 1 is used as the timer operation source, and the fuel oil pressure and the spring 2 are
The timer piston 3 is displaced by the balance, and the roller holder 5 connected to the piston 3 via a pin 4 is rotated.

As shown in FIG. 3, the timer piston 3 is formed with an orifice 7 that connects the low-pressure side chamber 6 in which the spring 2 is disposed and the fuel injection pump chamber 1. Two outlet ports 8 and 9 having different areas are formed.

A cylinder portion 10 housing the timer piston 3 is provided with an outlet 11 for low-pressure fuel oil, and the connection state between the outlet 11 and the outlets 8 and 9 is controlled in accordance with the displacement of the timer piston 3.

For example, at low engine speeds when the fuel pressure in the fuel injection pump chamber 1 is low, the advance angle is delayed the most. When the fuel pressure in the fuel injection pump chamber 1 increases, the timer piston 3 moves and advances, and the outlet port 9 is opened.

In the above configuration, the pressure in the chamber 6 on the low pressure side can be adjusted by arbitrarily selecting the areas of the orifice 7 and the outlet 8°9, so that the advance angle characteristic can be arbitrarily controlled.

In other words, if the cross-sectional area of the outlet 8 is smaller than the cross-sectional area of the orifice 7 and the cross-sectional area of the outlet 9 is made larger, the pressure on the low pressure side of the timer piston 3 will remain constant while the outlet 8 is in communication. The timer advances later than when it normally operates.
When the timer advances until the outlet 9 is communicated, the pressure on the low pressure side becomes lower than before and the advance characteristic becomes better (see broken line A in FIG. 2).

On the other hand, if the cross-sectional area of the outlet 8 is made larger and the cross-sectional area of the outlet 9 is made smaller, the advance angle/rotational speed characteristics will be such that the advance angle tends to start at low revolutions and then lag midway (broken line B in Figure 2). reference)
.

By setting the number of outflow ports to two or more, the control characteristics can be set arbitrarily.

According to this invention, since the timer performance can be set to any desired characteristic, it becomes easy to meet engine requirements, and an injection pump that is advantageous in exhaust gas countermeasures can be obtained, which is practically effective.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing a state in which the timer and roller holder are connected. FIG. 2 is an advance angle/rotation speed diagram. FIG. 3 is a longitudinal sectional view of the main parts of the timer according to this invention. 1: fuel injection pump chamber, 3: timer piston, 6: chamber,
7: Orifice, 8, 9: Outlet, 10 Niji cylinder part,
11: Outlet.

Claims (1)

[Scope of utility model registration request] Fuel oil is pressurized and distributed to each cylinder of a multi-cylinder internal combustion engine using a rotating and reciprocating plunger, and the timer piston is moved against a spring using the fuel oil that is pressurized by a feed pump and supplied into the fuel injection pump chamber. In a type of fuel injection pump for internal combustion engines that adjusts the injection timing by displacing the piston and rotating a roller holder connected to the piston via a pin, the fuel injection pump chamber and the low pressure side are connected to the timer piston. A fuel injection system for an internal combustion engine in which an orifice is provided, a plurality of outlets with different cross-sectional areas are provided on the side wall of the timer piston, and an outlet is provided in the cylinder portion that accommodates the timer piston that communicates with the outlet of the timer piston by displacement of the timer piston. Pump timer.