JPS6018603Y2 - Fuel injection pump with hydraulic timer - Google Patents

Description

[Detailed description of the invention] The present invention enables fuel to be pumped by reciprocating a plunger within a barrel, and at the same time, an annular valve is fitted on the outside of the plunger and the expression valve and the plunger are rotated relative to each other. The fuel injection timing is controlled by displacing the annular valve relative to the plunger in the axial direction by a piston that is displaced in accordance with the feed pressure of a feed pump that rotates synchronously with the engine. The present invention relates to a fuel injection pump that can be used as a fuel injection pump.

In order to improve various performances of a diesel engine, such as its operating noise and exhaust gas emissions, it is necessary to adapt the advance angle characteristics of the fuel injection pump to each rotational speed of the engine.

However, conventional fuel injection pumps with hydraulic timers
The piston, which is displaced in response to the feed pressure of the feed pump, is directly connected to the annular valve that controls the timing of fuel injection, and the annular valve is linearly displaced in accordance with the displacement of the piston. The advance angle characteristics of pumps are standardized, making it impossible to adapt the advance angle characteristics to each rotation speed of the engine, and as a result, problems such as engine operating noise and exhaust gas emissions deteriorate. there were.

In view of the above-mentioned problems with conventional fuel injection pumps with hydraulic timers, the present invention improves various aspects such as engine operating noise and exhaust gas emissions by adapting the advance angle characteristics to each engine speed. The purpose of this invention is to provide a fuel injection pump with a hydraulic timer that can be further improved. The present invention is characterized by the provision of an appropriate transmission mechanism that acts to non-linearly transmit the displacement of the piston to the annular valve via a cam.

Below, the fuel injection pump with hydraulic timer of the present invention will be described as the first example.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the embodiment shown in FIGS. 1 to 5, FIGS. 1 to 3 show a fuel injection pump Z with a hydraulic timer according to an embodiment of the present invention.

This fuel injection pump Z includes a pump device X for pumping fuel, a camshaft 4 for driving the pump device X, and a feed pump 6 for supplying fuel to the pump device X. ing.

The pump device X has a barrel 1 as shown in FIGS. 3 and 4.
While the fuel can be pumped by reciprocating the plunger 12 within the plunger, an annular valve 1 is installed on the outside of the plunger.
3 is slidably and rotatably inserted and the annular valve 13 is rotated relative to the plunger 12, thereby forming an oil passage hole 15 communicating with the top surface 12a of the plunger 12 and a spill hole formed in the annular valve 13. 18 to control the fuel injection amount by adjusting the fuel release timing,
Furthermore, four pump single-cylinder units 9, which control the fuel injection timing by displacing the annular valve 13 in the axial direction of the plunger 12, are installed in the pump mounting holes 8, 8, . . . formed in the pump casing 1. It is installed and configured.

Each annular valve 13 of each pump single cylinder unit 9, 9...
13... are simultaneously rotated by an adjustment operating rod 24 that is moved forward and backward in the axial direction according to the displacement of a governor device 5 attached to one end of a camshaft 4 that rotates in synchronization with the engine, and is engaged with the circumferential groove 19. Eccentric head 26 inserted
The timer pins 25, 25, .

One end of this metering operation rod 24 and one end 40 of the advance angle operation rod 40
a penetrates one side wall 1a of the pump casing 1, and projects into a governor chamber 36 formed by covering the side wall 1a with a governor cover 2.

In FIG. 3, reference numeral 11 is a fuel chamber formed on the outside of the annular valve 13, and the fuel chamber 11 accommodates the camshaft 4 through communication holes 21, 21, etc. provided in the tappet 14. It is communicated with the cam chamber 35.

Further, 16 is a reed, 17 is a fuel suction hole, 20 is a fuel pressurizing chamber, 22 is a delivery valve, 23 is a plunger spring, and 27 is a converter that converts the forward and backward displacement of the advance angle operation rod 40 into rotational displacement of the timer piston 25. The fan-shaped gear 28 acting as a force is an average rate adjustment pin for adjusting the unevenness of the fuel injection amount between each pump single cylinder unit, unit 9, 9, etc., and the average rate adjustment pin 28 is used to adjust the eccentricity of A spring receiver whose head 28-a is fixed to the plunger 12 is engaged with a member 29.

The camshaft 4 is provided to pass through the pump casing 1, and fuel cams 31, 31, etc. formed in the middle part of the camshaft 4 are accommodated in a cam chamber 35 communicating with each of the pump mounting holes 8, 8, etc. On the other hand, one end 4a on the cam gear device side is made to protrude outside, and the other end 4b is made to protrude into the governor chamber 36, respectively.

A governor device 5 for driving the metering operation rod 24 and a feed pump 6 for supplying fuel to the pump device X are attached to one end 4b of the camshaft 4 that projects into the governor chamber 36. It is being

The feed pump 6 sucks fuel from a fuel port 37 formed in the pump casing 1 as the camshaft 4 rotates, and feeds it to the cam chamber 35 at an appropriate supply pressure.

The discharge pressure of this feed pump 6, that is, the feed pressure is:
It changes approximately in proportion to the rotational speed of the camshaft 4, that is, the engine rotational speed.

Further, the cam chamber 35 and the governor chamber 36 are communicated with each other through communication holes 38, 38, etc. formed in the side wall 1a of the pump casing, and the fuel sent from the field pump 6 to the cam chamber 35 side is communicated with each other. A part of the fuel is pumped to the cylinder side by the pump device X, but the other surplus fuel that is not pumped to the cylinder side flows into the governor chamber 36 and is sent to the fuel tank from the fuel outlet 39 attached to the governor case 2. The water is forced to flow back to the side.

Therefore, the fuel pressure in the governor chamber 36 changes depending on the rotation speed of the camshaft 4.

A hydraulic timer mechanism (2) for controlling the advance angle operating rod 40 is installed in the governor chamber 36 in which the internal pressure (fuel pressure) changes in response to changes in the rotational speed of the camshaft 4.

The hydraulic timer mechanism (2) detects changes in engine speed as changes in fuel pressure in the governor chamber 36, and moves the advance control rod 40 forward or backward as appropriate based on the change, as shown in Fig. 1. , as shown in FIGS. 2 and 4, a piston 55 that is moved forward and backward in the axial direction according to the fuel pressure in the governor chamber 36, and a piston 55 that is interposed between the piston 55 and the advance control rod 40. a transmission mechanism Y that acts to transmit the displacement of
It has a timer spring 43 that acts to always bias the timing in the retard direction.

The piston 55 is a straight cylindrical body having an engagement protrusion 56 of a transmission mechanism Y, which will be described later, protruding from its top outer circumferential surface 55b. It is attached so that it can move forward and backward in a direction perpendicular to the axial direction of the governor chamber 36, and is always urged by a piston spring 57 so as to protrude toward the governor chamber 36 side.

Further, the back pressure side of the piston 55 is connected to the fuel tank 7 via an oil relief passage 59, and the piston 55 is driven by the relationship between the fuel pressure acting on its top surface 55a and the spring force of the piston spring 57. It can be driven forward and backward in the axial direction as appropriate.

At this time, the piston 55 is rotated while the engagement protrusion 56 remains directed in the direction of withdrawal of the advance angle operation rod 40 (in the direction of arrow C) by the anti-rotation pin 61 disposed on the side thereof. At the same time, the maximum amount of protrusion is regulated by a stopper 53 disposed opposite to the top surface 55a.

As shown in FIG. 4, the transmission mechanism Y has a straight bar-shaped engagement protrusion 56 attached to the piston 55 side, and an appropriate cam shape that is removably fastened to one end 40a of the advance angle operating rod 40. It is composed of a cam 48, and an engagement protrusion 56 is engaged with the cam 48 to act to move the advance angle operating rod 40 back and forth in the axial direction as the piston 55 moves back and forth.

The cam shape of the cam 48 is such that when the piston 55 is displaced in the direction of arrow A, in other words, when the engine speed increases, the advance angle operating rod 40 is displaced in the advance direction (arrow C direction). The slope is such that it is possible to

If the cam surface 49 is formed into a planar shape, the advance angle changes linearly with respect to the change in engine speed, as shown by the solid line in FIG. 5, but if the cam surface 49 is formed into an appropriate curved surface By forming this, the advance angle can be made into a curved shape having an arbitrary curve according to the change in the engine speed, as shown by the broken line 1JL2 and the chain line 3 shown in the figure.

That is, by changing the cam shape of the cam 48, arbitrary advance angle characteristics can be obtained.

Further, this cam 48 is connected to a timer spring 4 interposed between one end 40a of the advance angle operating rod 40 and the adjustment screw 42.
3, it is always urged toward the engaging protrusion 56 side.

Next, the operation of the fuel injection pump Z of the illustrated embodiment will be explained. When the engine is started and the feed pump 6 is rotated together with the camshaft 4, the fuel in the fuel tank is pumped into the cam chamber 35 at an appropriate pressure by the feed pump 6. pumped into the
Further, from the cam chamber 35, each pump single cylinder unit 9, 9.
・Communication holes 21, 21 provided in tappet 14, 14...
... into each fuel chamber 11,11....

Of the fuel that has flowed into each fuel chamber 11, 11..., a part of it flows from the fuel suction hole 17 of the plunger 12 through the oil passage hole 15 as the plunger 12 reciprocates into the fuel pressurizing chamber. 20 and is pressurized and delivered to the delivery valve 2.
2 to each cylinder (not shown), and other surplus fuel flows into the governor chamber 36 through communication holes 3B, 38, etc. provided in the side wall 1a of the pump casing, and then flows through the fuel outlet 39. The fuel is then returned to the fuel tank 7 side.

The amount of fuel injected by the pump device This is done by changing the communication timing between the 12 oil passage holes 15 and the spill hole 18 of the annular valve 13.

On the other hand, the fuel injection timing is determined by appropriately moving the piston 55 forward and backward depending on the fuel pressure in the governor chamber 36 (that is, the feed pressure of the feed pump 6), which changes approximately in proportion to the engine speed.

That is, the engine speed increases and the top surface 55a of the piston 55
When the fuel pressure acting on the piston 55 increases, the piston 55
moves in the direction of arrow A against the spring force of the piston spring 57, and displaces the forward/backward operating rod 40 by an appropriate amount in the direction of arrow C via the transmission mechanism Y.
25... to move the annular valve 13 of each pump single-cylinder unit 9, 9... down to advance the injection timing.

On the other hand, when the engine speed decreases and the fuel pressure in the governor chamber 36 decreases, the top surface 55a of the piston 55
As the fuel pressure acting on the engine gradually decreases, the piston 55 is gradually displaced in the direction of arrow B by the spring force of the piston spring 57, and the advance angle operating rod 40 is moved in the direction of the arrow B by the spring force of the timer spring 43. Each timer pin 25, 25... and the annular valve 13.1
3. Moves upward to delay the injection timing.

Next, to explain the effects of the present invention, the fuel injection pump with a hydraulic timer of the present invention is fitted onto the outside of a plunger, and is displaced relative to the plunger in the axial direction, thereby controlling the fuel injection timing. Between the annular valve that acts to act as if the engine were to move and the piston that is displaced in response to the feed pressure of the feed pump that rotates synchronously with the engine, there is an appropriate mechanism that acts to non-linearly transmit the displacement of the piston to the annular valve via a cam. By changing the transmission characteristics of this transmission mechanism, the advance angle characteristics of the fuel injection pump can be adapted to each rotation speed of the engine, and as a result, the engine operating noise, This has the effect of further improving various aspects such as exhaust gas emissions.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view of a fuel injection device with a hydraulic timer according to an embodiment of the present invention, FIG. 2 is a partially sectional view taken along the line nn (partially sectional) of FIG. 1, and FIG. 3 is a view of FIG. Figure 4 is an exploded perspective view of the main parts of the fuel injection pump in Figure 1, Figure 5 is a vertical sectional view of
The figure is a lead angle characteristic curve diagram. 6... Feed pump, 10... Barrel, 12... Plunger, 13... Annular valve, 48... Cam, 55... ...Zeston, Y...Transmission mechanism.

Claims (1)

[Scope of utility model registration request] Fuel can be pumped by reciprocating the plunger 12 within the barrel 10, while an annular valve 13 is fitted on the outside of the plunger 12 and the annular valve 13 and the plunger 12 are relatively rotated to transfer the fuel. The fuel injection timing is controlled by controlling the injection amount and displacing the annular valve 13 relative to the plunger 12 in the axial direction by a piston 55 that is displaced according to the feed pressure of the feed pump 6 that rotates synchronously with the engine. A fuel injection pump with a hydraulic timer, wherein the piston 5
5 and the annular valve 13, an appropriate transmission mechanism Y is interposed between the annular valve 13 and the annular valve 13. with fuel injection pump.