JPS6233983Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Field of application of the invention] This invention is a method for injecting high-pressure fuel into the combustion chamber of an engine.
The present invention relates to a fuel injection pump for a cylinder fuel injection type internal combustion engine that performs combustion.

[Background of the idea]

In a direct fuel injection type internal combustion engine, a fuel injection pump is used to inject fuel at high pressure to overcome an increase in engine compression pressure. For example, in a diesel engine that uses light oil as fuel, the gap between the sliding surface between the cylinder and the plunger that fits into the cylinder is reduced as much as possible, and the viscosity of the fuel itself minimizes the gap between the sliding surfaces. The pressure is set equal to zero, and fuel is injected at high pressure into the combustion chamber of the engine by changing the volume of the fuel due to the movement of the plunger.

However, due to the current fuel situation, attempts are being made to use alcohol, gasoline, etc. in addition to light oil in diesel engines that use light oil as fuel. In other words,
Alcohol, gasoline, etc. are injected at high pressure using a fuel injection pump, but when alcohol, gasoline, etc. are used in conventional injection pumps, due to the difference in fuel characteristics, the fitting and sliding of the cylinder and plunger inside the injection pump becomes difficult. There is a problem in that alcohol, gasoline, etc. leak more from the surface, and the cylinder and plunger seize due to insufficient viscosity of the fuel, making it impossible to actually use alcohol, gasoline, etc.

[Purpose of invention]

The present invention was developed in view of these problems, and it forcibly pumps lubricating oil into the gap between the cylinder and plunger that performs high-pressure pumping of fuel, thereby preventing fuel from leaking from this gap and improving lubrication. It is an object of the present invention to provide a fuel injection pump with a relatively simple structure that can improve performance.

[Summary of the idea]

That is, the configuration of the present invention includes, in addition to the first cavity for pressurizing fuel formed by the cylinder and the plunger, a second cavity for introducing and pressurizing lubricating oil,
Simultaneously with high-pressure fuel delivery by moving the plunger,
This fuel injection pump is designed to balance the fuel pressure in the first cavity and the lubricant pressure in the second cavity by applying high pressure of the lubricating oil in the second cavity to the first fuel cavity.

[Example of idea]

Next, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

As shown in FIG. 1, a fuel injection pump 1 includes a cam 2 connected to an engine output shaft (not shown) and a tappet 3 that abuts on the cam 2. A spring seat 4 disposed above the tappet 3 supports a spring 5, and the spring 5 urges the tappet 3 through the spring seat 4 so that it always comes into contact with the outer peripheral surface of the cam 2.

The plunger 6 connected to the spring seat 4 has a first outer circumferential surface 7 (small diameter) for pressure feeding fuel and a second outer circumferential surface 8 (large diameter) for feeding oil pressure. They are each formed by changing the A first inner circumferential surface 10 and a second inner circumferential surface 11 of the cylinder 9 are formed to fit into the first and second outer circumferential surfaces 7 and 8, respectively. Therefore, since the first outer circumferential surface 7 of the plunger 6 and the first inner circumferential surface 10 of the cylinder 9 are substantially sealed, the upper end 12 of the plunger 6 and the first inner circumferential surface 10 of the cylinder 9 are sealed. Thus, a first cavity 13 is formed. Similarly, since the second outer circumferential surface 8 of the plunger 6 and the second inner circumferential surface 11 of the cylinder 9 are substantially sealed, the first outer circumferential surface 7 of the plunger 6 and the second inner circumferential surface 7 of the cylinder 9, which have different shaft diameters, A second annular space 15 is formed surrounded by the second inner circumferential surface 11 and the stepped portion 14 of the plunger 6.

A feed hole 16 opens in the first cavity 13 to introduce fuel from the fuel chamber 17, and when the plunger 6 rises, the delivery valve spring 1
Delivery valve 19 is pushed open against the urging force of 8, and fuel is discharged at high pressure from jet port 20. still,
A reed 21 is opened in the plunger 6 so as to communicate with the first cavity 13, and when the plunger 6 rises above a certain value, the reed 21 and the feed hole 16 communicate with each other and fuel is supplied from the spout 20. stop.

Furthermore, the plunger 6 is connected to the control sleeve 2.
2, and its rotation is controlled by a control rack 24 via a control pinion 23.

A communication passage 25 communicates with the second cavity 15, and communicates with a communication passage 28 of a union 27 via a check valve 26. In this communication path 28, lubricating oil stored in an oil tank 29 is connected to a pipe 30,
Pump 33 via filter 31 and pipe 32
It is fed under pressure through a pipe 34. Also, pipe 34
Pipes 35 and 36 branch from there, and a regulator 37 controls the pressure of the lubricating oil. Incidentally, pipes 38 and 39 for returning lubricating oil are arranged from the bottom of the regulator 37 and the injection pump 1 toward the oil tank 29.

Next, the operation will be explained with reference to FIGS. 2 and 3.
2 and 3 are enlarged cross-sectional views of the left half of the plunger 6 and cylinder 9 shown in FIG.

FIG. 2 shows a state in which the plunger 6 is lowered, and the first cavity 13 is filled with fuel at low pressure. Further, lubricating oil pressurized at low pressure by the oil pump 33 is also introduced into the second cavity 15 from the communication passage 25 via the check valve 26. At this time, the pressures of the fuel and lubricating oil are equal, and each cavity 13,
Fuel and lubricant spills from 15 - no mixing.

FIG. 3 shows the state when the plunger 6 moves up inside the cylinder 9 as shown by arrow A. When the upper end 12 of the plunger 6 rises and reduces the volume of the first space 13, the first space 13 is reduced. The fuel in the nozzle 13 is pressurized and is forced toward the jet port 20, and is also pressurized and sent to the extremely small gap 40 formed by the contact surface between the plunger 6 and the cylinder 9. However, the lubricating oil in the second cavity 15 is also pressurized by the rise of the stepped portion 14 of the plunger 6, and when the path of the communication passage 25 is cut off by the check valve 26, it flows toward the gaps 40 and 41. It begins to flow out at high pressure.

Therefore, in the gap 40, the fuel from the first cavity 13 and the lubricating oil from the second cavity 15 are applied with high pressure to each other and are in an equilibrium state, thereby preventing leakage of fuel from the gap 40. Furthermore, since the lubricating oil also flows into the gap 41, the lubrication action of the plunger 6 and cylinder 9 is performed simultaneously.

Next, a second embodiment of the present invention will be described with reference to FIG. However, the same parts as in FIG. 1 and FIGS. 2 and 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

A communication passage 52 penetrating through the plunger 50 is formed with respect to the second cavity 51 of the plunger 50 corresponding to the plunger 6 in the first embodiment, and a first passageway 52 is formed to open on the outer circumferential surface of the plunger 50. An opening, that is, a lead 53 is formed.

Furthermore, a second opening, ie, a discharge port 55, is formed to communicate the inner circumferential surface 11 and the outer circumferential surface 54 of the cylinder 9. Note that the upper end 56 of the plunger 50
A hole 57 is formed in the hole 57 .

The lead 53 is formed and arranged in the following proportional relationship with the lead 21 communicating with the first cavity 58 that controls the amount of fuel. That is, the plunger 50
The time when the lead 21 of the first cavity 58 and the feed hole 16 of the cylinder 9 communicate with each other when the lead 53 of the second cavity 51 is raised is the same as the time when the lead 53 of the second cavity 51 and the discharge port 55 opening into the cylinder 9 communicate with each other. configured to be.

Therefore, when the fuel in the first cavity 58 is rotated and metered by the control pinion 23 and the control sleeve 22 via the control rack 24, the lubricating oil in the second cavity 51 is also pumped by the fuel. This is done at the same time as this to prevent excess lubricating oil from entering the fuel side.

[Effect of idea]

As explained above, according to the present invention, in addition to the first cavity where fuel is pressurized and fed, a second cavity where lubricating oil is pressurized and fed is formed in the same plunger and cylinder. Achieves a balance between the pressurized lubricating oil pressure and prevents fuel from leaking from the gap between the plunger and cylinder, and also maintains good lubrication between the plunger and cylinder by forcibly feeding the lubricating oil. There are benefits that can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the first embodiment of the present invention, and Figs. 2 and 3 are enlarged sectional views of the main parts of the same.
In particular, Figure 2 shows the state in which the plunger is lowered, and
The figures show the state in which the plunger is raised,
FIG. 4 is a sectional view of a second embodiment of the present invention. In the figure, 1... Injection pump, 6, 50... Plunger, 9... Cylinder, 12, 56... Upper end part,
13,58...first void, 14...stepped section, 15,
51...Second empty space, 16...Feed hole, 1
7...Fuel chamber, 20...Ejection port, 22...Control sleeve, 25, 28...Communication path, 29...
...Oil tank, 40, 41...Gap, 52...
...Communication path, 53...Lead (first opening), 55
...Exhaust port (second opening).

Claims (1)

[Claims for Utility Model Registration] (1) A cylinder and a plunger coaxially fitted into the cylinder, the fuel is provided in a first cavity formed by the inner peripheral surface of the cylinder and the upper end of the plunger. In this fuel injection pump, the fuel in the cavity is injected at high pressure by the volume change of this cavity due to the movement of the plunger, and the second cavity into which lubricating oil is introduced and pressurized is formed between the cylinder and the plunger. By applying high pressure to the lubricating oil in the second cavity towards the first cavity for fuel pressure feeding at the same time as the fuel is being fed under high pressure, the fuel pressure in the first cavity and the second cavity are reduced. A fuel injection pump characterized in that the pressure of lubricating oil is offset by a gap between the cylinder and the plunger. (2) A first opening communicating with the second cavity for sending lubricant oil pressure is formed in the outer circumferential surface of the plunger, and a second opening communicating between the inner circumferential surface and the outer circumferential surface of the cylinder is formed. However, when the plunger moves beyond a certain value, the first and second openings communicate with each other to stop the pressure feeding of the lubricating oil into the second cavity. fuel injection pump. (3) so that the communication distance between the first and second openings changes as the plunger is adjusted to rotate;
3. The fuel injection pump according to claim 2, wherein the first and second openings are formed.