JPS60233321A - Fuel injection pump for internal-combustion engine - Google Patents

Abstract

PURPOSE:To resolve the deviation in injection amount due to the dimensional deviation of machined parts by making the stroke of timing plunger adjustable that is disposed in the delivery side cylinder of a plunger pump. CONSTITUTION:A timing plunger 38 is slidably disposed in the delivery side cylinder of a plunger pump 8, and the communication is made to a pump chamber 13 via an orifice 39, annular groove 40 and orifice 41. A return spring 42 is attached to the other end of the timing plunger 38, and, by changing the position of a stopper 44 that limits the movement of the timing plunger 38, the stroke of the timing plunger 38 can be adjusted. In this manner, the deviation in injection amount due to the deviation in the dimension of machined parts or in assembly dimension can be resolved.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Industrial Application Field 1 The present invention relates to an electromagnetic spill type fuel injection pump that supplies fuel to diesel engines and the like.

(-Prior art) Overflow type fuel Flj in electromagnetic spill type fuel injection pump
As R means, Japanese Patent Publication No. 51-34939 is known. This system controls the injection amount by causing high-pressure fuel pressurized by a plunger to overflow to the low-pressure side using a solenoid valve, but an electronic control device such as a microcomputer is used to operate the solenoid valve. are doing. The electronic control device uses a pulse generator disposed opposite the drive shaft to generate a pulse at a certain time before the bottom dead center of the plunger, and sends this pulse to the electronic control device, This electronic control device outputs an output signal (current) after an appropriate delay time to operate the electric I/λ door P. Specifically, (A) is explained based on No. 4 [1]. Shows the signal characteristics generated by a pulse generator at a constant phase such as plunger bottom dead center (1, (B
) indicates the lift characteristics of the plunger. (C) shows the operating timing characteristics of the solenoid valve. After a certain rotation angle (θ) has elapsed from the signal from (A) (actually, it is processed in time in the electronic control unit), create a solenoid valve in the machine of (C). When the needle valve is opened, the high-pressure fuel overflows and an injection mq corresponding to the rotation angle (θ) described in 1. is obtained.

[Problem that the invention seeks to solve]

However, due to variations in component processing dimensions or assembly dimensions, as shown in Figure 4, the plunger software timing (B) with respect to the signal phase (A) from the pulse generator differs from the solid line showing the design value. If there is a deviation as shown by the broken line, the predetermined rotation angle θ(
If the solenoid valve is operated after a certain period of time has elapsed, the injection amount will change from q to q'.

The present invention was made based on the above circumstances, and its purpose is to provide an electromagnetic system that provides a mechanism for adjusting the timing of the start of fuel pumping and eliminates variations in injection amount due to variations in component processing dimensions or assembly dimensions. The present invention provides a spill type fuel injection pump.

[Means and operations for solving the problem] The present invention provides a cylinder section into which high-pressure fuel flows into communication with the discharge port side of the plunger pump, and a timing plunger in the cylinder that is operated by a return spring to absorb the fuel flowing into the cylinder. The timing plunger is biased in the direction of pushing out, and the movement and collapse of the timing plunger is restricted by a stopper. Furthermore, the position of the stopper is adjustable.

Therefore, even when the plunger pump starts pumping fuel, the fuel flows into the cylinder without being injected from the nozzle immediately. The timing plunger hits the stopper and no more fuel can flow into the cylinder (
Only then will fuel injection from the nozzle begin. In other words, the fuel injection timing is delayed by the amount of time the fuel flows into the cylinder. This delay time is determined by the effective capacity of the cylinder, and the effective capacity can be adjusted with the stop/par. Therefore, even if there are variations in the lift characteristics of the cams, the fuel injection start timing can be adjusted to be the same by adjusting the position of the stopper.

[Embodiment J] An embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a sectional view of a fuel injection pump according to the present invention, FIG. 2 is an enlarged view of the part indicated by the arrow A in FIG. 1, that is, the cylinder portion having the timing plunger, and FIG.
FIG.

A drive shaft 1 linked to the crankshaft of an engine (not shown) rotates a vane type feed pump 2, which introduces fuel through an intake port 3, pressurizes it, and pumps this fuel through a fuel pressure regulating valve 4 to a predetermined level. After the pressure is regulated, it is supplied to a fuel chamber 6 formed within the pump housing 5. The drive shaft 1 drives a pumping plunger 8 via a coupling 7. The compression ring 7 rotates the pressure-feeding plunger 8 integrally in the rotational direction, but allows the pressure-feeding plunger 8 to freely reciprocate by 1° in the axial direction.
The face cam 9 is integrated into the camera. The face cam 9 is pushed by the front link 10 and the cam roller 1
It is pressed to 1. Cam roller 11 and face cam 9
Due to these sliding contacts, the cam crest of the face cam 9 is placed on the cam ``1-ra 11'' and the plunger 8 is
is reciprocated the number of times corresponding to the number of cylinders during one rotation. 1
The feed flange 8 is fitted into a head 12 fixed to the housing 5 to form a pump chamber 3.

A suction groove 14 is formed in the pressure-feeding plunger 8,
When one of the suction grooves communicates with the suction boat 15 during the suction stroke of the pressure-feeding plunger 8, the fuel chamber 6 is connected to the pump chamber 1.
3. Introduce fuel.

When the fuel in the pump chamber 13 is compressed during the compression stroke of the pressure-feeding plunger 8, the fuel is sent from the distribution boat 16 through the pressure-feeding valve 17 to the fuel injection valve (not shown) of each cylinder, and then injected into the combustion chamber of the engine. A fuel metering mechanism 20 is connected to the chamber 13 . This fuel metering mechanism 20 operates when a current is passed through the coil 22 of the solenoid valve 21 to cause the needle valve 23 to
is lifted, and the fuel in the high-pressure pump chamber 13 flows into the overflow channel 2.
4.25 to be returned to the fuel chamber 6. Therefore, when the electromagnetic valve 21 is operated during the compression stroke of the pressure-feeding plunger l--8, fuel injection ends.

Here, the IJ period for starting energization of the solenoid valve 21 is controlled by an electronic control device 26 such as a microcomputer. The electronic control device 26 performs a logical function based on input signals of engine operating conditions detected by various sensors of the engine, such as an engine rotation sensor, an accelerator pedal sensor, and a temperature sensor, as well as input signals from a timing detector to be described later. The output signal is calculated by and sent to the coil 22 of the electromagnetic valve 21. Therefore, the solenoid valve 21 opens and closes in response to the output signal of the electronic production device 26.

Cam roller No. 11, which serves as the conversion member, is held by a roller ring 27. This Rollaring 2Z has a fuel injection timing adjustment mechanism 30 (timer)! This is how it is activated. 1.4 adjustment mechanism No. 30 is equipped with a timer piston 31 for adjusting the fuel injection timing. One end surface of this timer piston 31 receives the fuel pressure force L i'i )IJ of the fuel chamber 6, and the other end surface receives the pressure of the spring 32. The timer cylinder No. 31 moves to the left and right +ru in FIG. 3 due to the fuel pressure in the fuel chamber 6. Soimer piston 310 o i1! fJ 1 Yamaban Mabishi; 3:
The roller ring 271 is transmitted through the roller 3 and the roller ring 27 is rotated. For this reason, force 1. ．． The l-51 contact with the face cam 9 such as Ul-ra 11 (1 because it rubs); the adjusting mechanism 30 of the pressure-feeding plunger 8 with respect to the drive shaft 1 is actually arranged so that the axial direction of the timer piston 31 is perpendicular to the plane of the paper. Although it is set up, it is shown as shown in the drawing.

A timing detector 35 such as an electromagnetic pickup type is integrally attached to the roller ring 27, and a pulser 36 as a signal generating means is attached to the drive shaft 1. Formed in balsa 36 by rotation of drive shaft 1 = 2: W35efflt7J6&'
:4 :'>lk*”B2::Sends two signals, and this message,
The electronic control device v! 26 (send.Electronic control unit 2
6, upon receiving the output signal from the timing detector 35, outputs an operation command signal to the solenoid valve 21 after a predetermined period of time. The radial phase of each of the protrusions 37a to 37d is set to coincide with each F dead center of the pumping plunger 8. The phase setting accuracy is the processing accuracy of the protrusions 378 to 37d,
It will be affected by the accuracy of attachment to the drive shaft 1, the processing accuracy of the face cam 9, the processing accuracy of the coupling 7, etc.

A timing plunger 38 is installed in the head 12 in an oil-tight and slidable manner, and one end is connected to a communication hole 39 provided in the head 12, an annular groove 40. The fuel pressure in the pump chamber 13 is constantly received through a communication hole 41 provided in the pressure-feeding plunger 8 .

A return spring 4 is attached to the other end of the timing plunger 38.
A spring chamber 43 accommodating a spring 42 is communicated with the fuel chamber 6 . When the fuel pressure in the pump chamber 13 increases due to the compression stroke of the pressure-feeding plunger 8, the timing plunger 38 moves against the reaction force of the return spring 42.

The mounting load of the return spring 42 is set lower than the valve opening pressure of a fuel injection valve (not shown). timing plunger 3
The amount of movement of the timing plunger 8 is determined by the position where it hits a stopper 44 coaxially arranged on the head 12, and by changing the position of the stopper 44, the amount of movement of the timing plunger 38 can be adjusted. The stopper 44 is screwed into the head 12, its position adjusted by screwing 1, and fixed by a lock nut 45. An O-ring 46 is attached to the stopper 44 to prevent fuel from leaking out of the head 12. The operation of this embodiment will be described below.

Figure 5 shows the characteristics of this example, and (
A) is the reference signal characteristic from the pulse generator, (B) is the lift characteristic of the pressure-feeding plunger, (C) is the actuation timing characteristic of the solenoid valve, (D) is the lift characteristic of the timing plunger, (E) is the fuel injection This figure shows the characteristics of the fuel injected from the valve.

As shown in characteristic (B), when the actual product is manufactured as shown by the broken line with respect to the design value shown by the solid line, the pump chamber 13
The fuel pressurization start timing is b. Since the mounting load of the return spring 42 of the timing plunger 38 is set lower than the valve opening pressure of the fuel injection valve, before the fuel is pumped, the timing plunger 38 is set as shown in characteristic (D).
is activated. When the timing flancher 38 hits the stopper 44 and the operation ends, fuel feeding starts as shown in characteristic (E).

In other words, by adjusting the amount of movement of the timing plunger 38, even if there are variations in the pressure-feeding plunger tire lift characteristics, it is possible to make the fuel pressure-feeding start timing the same, and it is possible to make the fuel pressure-feeding start timing the same with respect to the reference signal of characteristic (A). Predetermined rotation angle θ
(for a certain period of time) later, the same fuel injection M
can be obtained. After the solenoid valve is activated, the fuel in the pump chamber 13 is returned to the fuel chamber 6 through the overflow passage 24, 25 and the fuel pressure is reduced, so the timing plunger 38 is pushed by the return spring 42 and returns to its original position. Waiting for the next fuel pumping.

In this embodiment, the movement amount of the timing plunger 38 is adjusted by a screw-in type stopper 44, but the invention is not limited to this, and for example, a drive-in type stopper may also be used. ] As explained above, according to the present invention, it is possible to eliminate variations in the injection amount caused by errors in component processing dimensions or assembly dimensions by adjusting the fuel injection start timing, and to obtain the same fuel injection amount. There is an effect that can be done.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of one embodiment of the present invention, Fig. 2 is a cross-sectional view of arrow A in Fig.
Figure 4 shows the conventional device 1'? Figure 5 is a chart showing the operation of the device according to the present invention.
tl) A. ]...PJ14 moving shaft, 2 vane pump, 3 ・Suction 1
1.6 ・Fuel gear, 8 Pressure feeding plunger, 9 Face cam, 10 ・Spring, 11・-Cam roller, 1
3・Pump chamber, 14 Suction groove, 15・Suction port,
16 Distribution boat, 17... Pressure feeding valve, 21... Solenoid valve, 23 - Needle valve, 24. 25 - Overflow path, 26...
Electronic control unit, 30 Fuel injection timing adjustment mechanism, 31 =
-Timer piston, 35...timing detector, 38
・・Timink Franscher, 39-1 communication hole, 40・-
Annular groove, 41... communication hole, 42, return spring, 4
3.Spring chamber, 44.Stopper, 45. Mouth, socknant, 46.0 ring. Representative Patent Attorney Yusaku Go Iji Figure 1 Figure 2 Figure 3 (A) Figure 4 Figure 5

Claims (1)

[Claims] High-pressure fuel pressurized by a plunger pump driven by a drive shaft interlocked with a crankshaft is injected from a nozzle, and the discharge port side of the plunger pump and the suction OpJ By opening the solenoid valve at a predetermined timing, high-pressure fuel overflows and is injected, and a high-pressure fuel amount is delivered to the discharge port side of the plunger pump.・The electromagnetic spill type fuel injection pump to be controlled is equipped with a ring section through which fuel flows, and the timing plunger inside the cylinder is biased by a return spring in the direction of pushing out the fuel inside the cylinder. A fuel injection pump for an internal combustion engine, characterized in that a stopper that limits the amount of movement of a timing plunger is attached to the position of the stopper at any position. 2. The spring pressure of the return spring is set such that the timing plunger starts moving against the spring pressure at a cylinder pressure lower than the opening pressure of the fuel injection valve. A fuel injection pump for an internal combustion engine according to claim 1.