JPH0447143B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection pump used in an engine that uses high viscosity, low quality oil such as C heavy oil as fuel.

(Prior art) Among fuel injection pumps, especially fuel injection pumps used in engines that use high-viscosity, low-quality oil such as C heavy oil, fuel leaks from the top side of the plunger to the bottom side of the plunger during operation. C heavy oil) adheres to the plunger spring and is thrown upward as the plunger reciprocates, causing it to mesh with the rack pinion (i.e., the rack gear of the metering rack), which constitutes the main part of the fuel metering mechanism. It may adhere to the pinion gear (pinion gear) on the plunger side and stick there, resulting in a stalemate.

As described above, when C heavy oil cakes on the rack and pinion portion, its viscous resistance inhibits the operation of the rack and pinion, and as a result, the metering rack no longer follows the displacement of the governor device. Therefore,
For example, when starting an engine, the metering rack is positioned on the fuel increase side, but in this case, even if you try to shift the engine to idling after the engine has completely exploded, the metering rack will be on the fuel decrease side. There is a risk that a situation may occur in which the engine does not move and the engine runs out of control while operating at high speed, and the engine cannot be stopped.

In addition, in order to solve such problems, for example, when the engine is stopped, warm C heavy oil is circulated from the fuel supply passage toward the oil discharge passage to prevent leaked oil from caking. Low viscosity heavy oil A is temporarily used as fuel when starting and stopping the engine, and when the engine is stopped, the above heavy oil A remains on the top side of the plunger to prevent caking in the metering mechanism when starting the engine. However, in these methods, when the amount of circulating oil is low in cold weather, the fuel remaining on the sliding part of the plunger becomes stuck there, and the camshaft of the plunger spring is damaged. There is a problem that the return action to the side is impaired and the pump characteristics deteriorate, so it is not considered to be a very effective means.

(Object of the Invention) The present invention is intended to solve or improve the problems pointed out in the above section of the prior art, and is directed to a fuel injection pump used in an engine that uses high viscosity, low quality oil such as C heavy oil as fuel. By preventing the leakage of the fuel to the lower end of the plunger as much as possible, deterioration of the operating characteristics of the fuel injection pump due to caking of the leaked fuel is prevented, and the operation of the fuel injection pump is thereby prevented. The purpose is to maintain the characteristics at a high level over a long period of time.

(Means for Achieving the Object) As a means for achieving the above object, the present invention reciprocates the plunger within the plunger sliding hole formed in the barrel, thereby pumping the fuel supplied to the fuel chamber. forming a gap facing the outer circumference of the plunger between the lower end of the plunger sliding hole and a first circumferential groove that communicates with the fuel chamber via a return oil passage; A cleaning oil supply means that circulates between the cleaning oil pump and the cleaning oil tank via the gap is provided independently of the fuel system communicating with the fuel chamber.

(Function) In the present invention, by the above-mentioned means, (1) The fuel leaking from the top of the plunger toward the lower end of the plunger and flowing into the gap is absorbed together with the cleaning oil from the cleaning oil supply means flowing through the gap. (2) The cleaning oil that leaks from the gap to the lower end of the plunger lubricates the rack and pinion parts that make up the metering mechanism, ensuring smooth operation. is obtained.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Structure) The drawing shows a fuel injection pump Z according to an embodiment of the present invention, in which reference numeral 1 indicates a pump body, 2
3 is a barrel, and 3 is a plunger fitted into a plunger sliding hole 4 formed in the barrel 2 so as to be slidable and relatively rotatable. This plunger 3 is reciprocated by the spring force of a plunger spring 16 and the cam force of a fuel cam (not shown) transmitted via a plunger guide 17 that interlocks with a tappet (not shown). The fuel in the fuel chamber 7 is sucked into the pressurized chamber 5 formed above through the oil escape port 8 and pressurized, and is then forcefully delivered from the delivery valve 6 to the fuel injection valve (not shown) attached to the engine. It acts as it does.

A plunger rotation ring 13 that engages with the plunger 3 in its rotation direction (circumferential direction) is fitted onto the outside of the lower end portion 2a of the barrel 2 so as to be relatively rotatable. A pinion gear 15 is formed on the outer periphery of the plunger rotating shaft 13 and meshes with a rack gear 14 of a metering rack 12 provided so as to be movable forward and backward in a direction perpendicular to the axial direction of the plunger 3. Therefore, when the metering rack 12 is moved back and forth by a governor device (not shown), the plunger 3 is rotationally displaced via the plunger rotation shaft 13, and the top surface is moved from the outer circumferential surface of the top portion 3b to the top surface. The timing of communication between the oblique groove-shaped lead 9 formed over 3c and the oil escape port 8 changes,
The fuel injection amount is increased or decreased.

On the other hand, on the inner circumferential surface of the plunger sliding hole 4 of the barrel 2, there are three circumferential grooves 1 spaced apart appropriately in the axial direction.
1, 21, and 31 are formed. Among these three circumferential grooves 11 , 21 , 31 , the first circumferential groove 11 located at the uppermost stage is communicated with the fuel chamber 7 via the return oil passage 10 . In this embodiment, the oil escape port 8 and return oil passage 10 constitute a "fuel system" in the claims.

The second circumferential groove 21 located in the middle section corresponds to a "gap" in the claims, and one end thereof is connected to the cleaning oil pump 3 via the cleaning supply oil path 35.
7, and the other end is connected to a cleaning oil tank 36 via a leakage oil discharge oil path 34, respectively. Therefore, the cleaning oil discharged from the cleaning oil pump 37 (A heavy oil is used in this embodiment, but this cleaning oil may be any oil that impairs lubricity and is mixable with C heavy oil). (for example, light oil or lubricating oil may be used instead of heavy oil A) is sequentially circulated from the cleaning oil supply oil passage 35 through the second circumferential groove 21 to the leaked oil discharge oil passage 34 side. In this embodiment, the leaked oil discharge passage 34, the cleaning oil supply passage 35, the cleaning oil tank 36, and the cleaning oil pump 37 constitute the "cleaning oil supply means" in the claims. .

The third circumferential groove 31 acts as a temporary reservoir for the cleaning oil, as will be described later, and is in the form of a sealed space when the plunger 3 is inserted.
Further, the formation position of the third circumferential groove 31 in the vertical direction is set according to the stroke of the plunger 3 and the formation position of the second circumferential groove 21, as described below. That is, an annular groove 24 is formed in the middle portion of the plunger 3 so as to overlap and communicate with the gap 21 (shown by chain lines, 24') at its top dead center position (3'). When the plunger 3 is positioned at the bottom dead center position (the position shown by the solid line), the annular groove 24 is aligned with the third circumferential groove 3.
The formation position of the third circumferential groove 31 is set so as to overlap and communicate with the third circumferential groove 31.

(Operation and its effects) Next, the operation and its effects will be briefly explained using an example in which this fuel injection pump Z is used in an engine that uses C heavy oil as fuel.As mentioned above, the fuel is pumped by a plunger. The fuel injection amount is controlled by the relative rotation of the plunger 3 and the barrel 2.

When pressurizing and feeding fuel, the pressure inside the pressurizing chamber 5 becomes extremely high at about 1000 kg/cm ² , so the fitting gap 39 between the plunger 3 and the plunger sliding hole 4 should be set to about 5 to 10 microns. (5 to 7 microns for small engines, 5 to 10 microns for large engines) Even if the dimensions are set to be as small as 5 to 7 microns for small engines, fuel C heavy oil passes from the pressurizing chamber 5 side through the fitting gap 39. is plunger 3
It will leak towards the lower end side.

When this fuel C heavy oil leaks to the lower end side of the plunger and flows down to the plunger spring 16 side, as explained in the prior art section, the C heavy oil with high viscosity leaks to the meshing part between the metering rack 12 and the plunger rotating wheel 13, etc. This results in a stalemate due to caking, which impedes a smooth metering mechanism.

However, in this fuel injection pump Z,
By applying the present invention, a second circumferential groove 21 is formed between the facing surfaces of the outer circumferential surface 3a of the plunger 3 and the inner surface of the plunger sliding hole 4, and a cleaning oil supply oil passage 35 is formed through the second circumferential groove 21. Since the and leakage discharge oil passage 34 are communicated with each other, leakage of fuel to the plunger spring 16 side is prevented, as will be described later.
As a result, the metering function caused by the stagnation of fuel leakage as described above is inhibited, and smooth sliding of the plunger 3 is realized. That is, as the fuel is pressurized and pumped, the high-pressure fuel oil that leaks from the pressurizing chamber 5 side through the fitting gap 39 toward the lower end side of the plunger 3 first flows through the first circumferential groove. 11 and is collected, and most of it is returned to the fuel chamber 7 side via the return oil passage 10. Therefore, the pressure of the fuel leaking oil in the first circumferential groove 11 is reduced to near the fuel feed pressure, and the fuel leaking oil further leaks from the first circumferential groove 11 toward the lower end of the plunger. is suppressed.

Even if the pressure of the fuel leaking oil is reduced in the first circumferential groove 11, a part of it further leaks from the first circumferential groove 11 toward the lower end of the plunger, and from this first circumferential groove 11 further downwards. The low-pressure fuel leaking out flows into the second circumferential groove 21, and the cleaning oil flows from the cleaning oil supply oil passage 35 side to the leaked oil discharge oil passage 34 side via the first circumferential groove 11. and is discharged to the outside (to the side of the cleaning oil tank 36) together with the cleaning oil. At this time, since the pressure of the fuel leaking oil itself is low and the cleaning oil is in a fluid state, the fuel leaking oil is
The cleaning oil is completely discharged to the outside together with the cleaning oil without further leaking from the circumferential groove 21 to the lower end side of the plunger. Therefore, malfunction of the metering mechanism due to sticking of fuel leakage is prevented.

On the other hand, the cleaning oil flowing in the second circumferential groove 21 further leaks from the second circumferential groove 21 toward the lower end of the plunger in place of the fuel leakage oil. Since high-quality oil with low viscosity such as heavy oil or light oil is used, smoother operation can be obtained by actively utilizing the cleaning oil as a lubricating oil for moving parts such as the plunger 3. In the above, the second circumferential groove 21, the third circumferential groove 31, and the annular groove 2 formed in the plunger 3.
4 to achieve this. That is, as the plunger 3 reciprocates, the annular groove 24 of the plunger 3 alternately communicates with the second circumferential groove 21 and the third circumferential groove 31, and the cleaning oil in the second circumferential groove 21 is sequentially circulated three times. Carry it to the groove 31 side. Therefore, the lubrication performance between the outer circumferential surface 3a of the plunger 3 and the plunger sliding hole 4 at the lower end 2a of the barrel 2 is improved when the third circumferential groove 31 and the annular groove 24 are not provided (in other words, when the third circumferential groove 31 and the annular groove 24 are not provided). 3), the lubrication effect of the cleaning oil is further improved, and the plunger 3 is moved more smoothly. This ensures proper operation.

Also, from the bottom end of the barrel 2 to the plunger guide 1
As the plunger 3 reciprocates, the cleaning oil that has flowed down to the 7 side attaches to the plunger spring 16 and is splashed upward, and the cleaning oil flows upward to the meshing part (rack/pinion part) between the metering rack 12 and the plunger rotating ring 13.
It acts to lubricate the meshing part by entering the shaft, or into the fitting gap 40 between the barrel 2 and the plunger rotating shaft 13 to lubricate the space between them. Therefore, the operation of the metering mechanism section is made light and smooth, and metering control that accurately follows the displacement of the governor device is realized.

Even in the fuel injection pump Z configured as described above, there is a risk that the viscosity of the cleaning oil increases and the operating characteristics of the metering mechanism decreases slightly when starting, especially in extremely cold regions. When used in extremely cold regions, steam pipes 51, 51... are wrapped around the outside of the metering mechanism as shown in the chain line diagram, and the metering is performed using steam or high-temperature water flowing through the steam pipes 51, 51... It is effective to heat and keep the mechanical parts warm to prevent the cleaning oil from becoming highly viscous. In addition, the reference numeral 52 in the figure indicates the steam pipe 5.
1 and a cushioning material disposed between the pump body 1 and the pump body 1;
is a covering material with heat insulating properties.

In addition, in the drawing, the steam pipe 51
is wound around the outside of the pump body 1, but in addition to such a structure, for example, a steam gear rally may be formed directly within the pump body 1, and steam or high-temperature water, etc. may be passed through this steam gear rally. You can also do it like this.

(Effects of the Invention) The fuel injection pump of the present invention enables fuel to be pumped by reciprocating the plunger within the plunger sliding hole formed in the barrel, and also allows the plunger to slide between the outer periphery of the plunger and the plunger. A leakage oil discharge passage for discharging fuel leaking from the top side of the plunger toward the gap side is communicated with the gap formed between the opposing surfaces between the inner circumferential surface of the hole and the inner peripheral surface of the hole. The injection pump is characterized in that a cleaning oil supply oil passage for supplying fuel cleaning oil that can be mixed with the fuel is communicated with the leakage oil discharge oil passage through the gap. It is.

Therefore, according to the fuel injection pump of the present invention, (1) Since the fuel leaking from the top of the plunger toward the bottom end of the plunger is discharged to the outside together with the cleaning oil during the leakage, the fuel leakage is prevented. (2) The lower end of the plunger is prevented from leaking to the lower end of the plunger and adhering to the metering mechanism, etc., causing a stalemate and impeding the smooth operation of the metering mechanism. The cleaning oil that leaks toward the side promotes the lubricity of the sliding parts of the metering mechanism, etc., ensuring their smooth operation. Even when using the fuel injection pump, there is an effect that the operating characteristics of the fuel injection pump are maintained at a high level over a long period of time.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of a fuel injection pump according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Pump body, 2... Barrel, 3... Plunger, 4... Plunger sliding hole, 21... Gap, 34... Leak oil discharge oil path, 35... Cleaning oil supply oil path.

Claims (1)

[Claims] 1 By reciprocating the plunger 3 within the plunger sliding hole 4 formed in the barrel 2, the fuel supplied to the fuel chamber 7 can be pumped, and the lower end of the plunger sliding hole 4 and the A first pipe communicating with the fuel chamber 7 via a return oil passage 10.
Between the circumferential groove 11 and the outer circumferential portion 3 of the plunger 3
a fuel system that communicates cleaning oil supply means 34, 35, 36, 37 that circulates between a cleaning oil pump 37 and a cleaning oil tank 36 with the fuel chamber 7 through the gap 21; A fuel injection pump characterized in that the fuel injection pump is provided independently for the fuel injection pumps 8 and 10.