WO2020098179A1

WO2020098179A1 - Plunger fuel injector and internal combustion engine

Info

Publication number: WO2020098179A1
Application number: PCT/CN2019/076980
Authority: WO
Inventors: 孙海东; 郭永青; 向桂蓉
Original assignee: 上海华羿汽车系统集成有限公司
Priority date: 2018-11-14
Filing date: 2019-03-05
Publication date: 2020-05-22
Also published as: CN109209710A; CN109209710B

Abstract

A plunger fuel injector, comprising: a body (1), wherein the body (1) is provided with a plunger hole, an inlet (5) of a fluid to be injected, an injection opening (6), and a lubricating oil inlet (7); a lower plunger (2) slidably fitted in the plunger hole, wherein the lower end of the lower plunger (2) is configured to open or close the injection opening (6); an injection chamber (8) formed between the lower end of the lower plunger (2) and the inner wall of the plunger hole, wherein said inlet (5) and the injection opening (6) are both configured to be in communication with the injection chamber (8); an upper plunger (3) slidably fitted in the plunger hole; a lubricating oil chamber (9) formed between the lower end of the upper plunger (3), the upper end of the lower plunger (2), and the inner wall of the plunger hole; a first one-way valve (10), wherein the lubricating oil inlet (7) is configured to be in communication with the lubricating oil chamber (9) by means of the first one-way valve (10); and a first resetting device (4) configured to provide a force to the upper plunger (3) for moving downwards. Also provided is an internal combustion engine comprising the plunger fuel injector. The plunger fuel injector and the internal combustion engine can reduce the problem of leakage while increasing injection pressure.

Description

Plunger injector and internal combustion engine

This application requires the priority of a Chinese patent application with an application date of November 14, 2018 and an application number of 201811351642.0. The entire contents of this application are incorporated by reference in this application.

Technical field

The present disclosure relates to the technical field of internal combustion engines, for example, to a plunger injector and an internal combustion engine.

Background technique

In recent years, on the one hand, in order to cope with the increasingly stringent emission requirements, the injection pressure of diesel engines is getting higher and higher, and ultra-high pressure injection brings better fuel atomization effect, but also brings about leakage and wear problems of injectors . On the other hand, alternative fuels such as methanol, ethanol, and dimethyl ether have also received certain research and application in internal combustion engines, and there is a trend of rapid expansion. However, these alternative fuels and these low-viscosity fluids including gasoline, when using high-pressure injection of related art fuel injectors, because of low viscosity, large leakage, and poor self-lubricating performance, the injection pressure is increasing. Difficult, the wear of the plunger and plunger hole is much more severe than when using diesel, which affects the reliability and durability of the injector.

Summary of the invention

The present disclosure proposes a plunger injector and an internal combustion engine, which can reduce the leakage problem while increasing the injection pressure.

An embodiment provides a plunger injector, including: a body provided with a plunger hole, a fluid inlet to be sprayed, an injection port, and a lubricating oil inlet; a lower plunger, which is slidingly fitted to the plunger In the hole, the lower end of the lower plunger is set to open or close the spray port; the spray chamber formed between the lower end of the lower plunger and the inner wall of the plunger hole, the fluid inlet to be sprayed and The injection ports are all set to communicate with the injection chamber; an upper plunger slidingly fits in the plunger hole; a lower end of the upper plunger, an upper end of the lower plunger and the plunger hole A lubricating oil cavity formed between the inner walls of the; a one-way valve, the lubricating oil inlet is arranged to communicate with the lubricating oil cavity through the first one-way valve; and a first reset device is arranged to The upper plunger provides downward force.

BRIEF DESCRIPTION

FIG. 1 is a schematic structural diagram of a plunger injector provided in an embodiment.

Reference mark:

1. Body; 2. Lower plunger; 3. Upper plunger; 4. First reset device; 5. Fluid inlet to be sprayed; 6. Injection port; 7. Lubricant inlet; 8. Injection chamber, 9. Lubricant Cavity; 10, first check valve; 11, second elastic member; 12, limit protrusion, 13, limit surface; 14, oil return chamber; 15, oil return outlet.

detailed description

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying the referred device Or the element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application.

This specific embodiment provides a plunger injector that is configured to inject fuel, methanol, ethanol, and dimethyl ether into the body of the internal combustion engine. In this specific implementation, the fluid to be injected is fuel Examples.

As shown in FIG. 1, the plunger injector provided in this embodiment includes a body 1, a lower plunger 2, an upper plunger 3, and a first reset device 4. The body 1 is provided with a plunger hole and a fluid inlet to be injected 5. Injection port 6 and lubricating oil inlet 7. Both the lower plunger 2 and the upper plunger 3 are precisely slidingly fitted into the plunger hole along the axial direction of the plunger hole, and the precision sliding fit means that the outer diameters of the lower plunger 2 and the upper plunger 3 are equal to or slightly smaller than the plunger respectively The inner diameter of the hole, as long as the lower plunger 2 and the upper plunger 3 slide along the plunger hole, the gap between the lower plunger 2 and the upper plunger 3 and the plunger hole is as small as possible. In one embodiment, the axis of the lower plunger 2 and the axis of the upper plunger 3 are collinear. The lower plunger 2 is located below the upper plunger 3, a spray chamber 8 is formed between the lower end of the lower plunger 2 and the inner wall of the plunger hole, and the fluid inlet 5 and the spray port 6 to be sprayed are in communication with the spray chamber 8, the lower plunger The lower end of 2 is set to open or close the injection port 6. For easy control, the fluid inlet 5 to be sprayed is preferably communicated with the spray chamber 8 through a check valve or a solenoid valve. There may not be any valve at the inlet 5 of the fluid to be sprayed, but the injection is controlled by the pressure of the fluid to be sprayed. In an embodiment, the lower end of the lower plunger 2 is tapered, the inner contour of the injection port 6 matches the outer contour of the lower end of the lower plunger 2, and a needle is formed between the lower end of the lower plunger 2 and the injection port 6 valve. A lubricating oil chamber 9 is formed between the lower end of the upper plunger 3, the upper end of the lower plunger 2 and the inner wall of the plunger hole. The lubricating oil inlet 7 communicates with the lubricating oil chamber 9 through the first check valve 10. The lubricating oil is set to provide a downward movement force to the lower plunger 2 when the plunger injector is injecting. The gap between the lower plunger 2 and the upper plunger 3 and the plunger hole is as small as possible to avoid mutual leakage between the lubricating oil and the fuel. The first reset device 4 is configured to provide a downward force to the upper plunger 3, wherein the downward motion is to move downward along the plunger hole, that is, the first reset device 4 is configured to provide the upper plunger 3 with a force closer to the lower plunger 2 Directional force.

The plunger injector provided in this embodiment has two plungers, and a lubricating oil chamber 9 communicating with the lubricating oil inlet through the first check valve 10 is defined between the two plungers and the inner wall of the plunger hole, lubricating The pressure of the lubricating oil in the oil chamber 9 can be changed with the change of the pressure of the fluid to be injected, so that the pressures received by the two end faces of the lower plunger 2 are approximately equal, and because the lower plunger 2 and the plunger hole are precisely matched, As a result, there is only a very small annular gap between the lower plunger 2 and the plunger hole. Theoretically, the pressure of the fuel in the injection chamber 8 and the lubricating oil in the lubricating oil chamber 9 can be balanced, and leakage and mixing will not occur. The problem of leakage can be avoided while increasing the fuel injection pressure; at the same time, the lubricating oil remaining on the inner wall of the lubricating oil chamber 9 during the up and down movement of the plunger can ensure effective lubrication between the plunger and the inner wall of the plunger hole.

In this specific embodiment, the first reset device 4 is a first elastic member. In an embodiment, the first elastic member is a spring. When the first elastic member is a spring, the axis of the first elastic member is collinear with the axis of the upper plunger 3. When the first elastic member is a spring, the first end of the first elastic member contacts the upper end surface of the upper plunger 3, and the second end of the first elastic member contacts the inner wall surface of the plunger hole. In order to facilitate the effective closing of the needle valve and the absorption of lubricating oil, the plunger injector also includes a second elastic member 11, which is arranged to provide a downward force to the lower plunger 2, that is, the second elastic member 11 is provided The lower plunger 2 is provided with a force to move away from the upper plunger 3. In an embodiment, the second elastic member 11 is a spring, and the axis of the second elastic member 11 is collinear with the axis of the lower plunger 2. The first end of the second elastic member 11 abuts the upper end surface of the lower plunger 2, and the second end of the second elastic member 11 abuts the inner wall of the plunger hole. The preload force of the first elastic member is greater than the preload force of the second elastic member 11. The pretension of the first elastic member and the second elastic member 11 refers to the elastic forces provided by the first elastic member and the second elastic member 11 respectively when the fuel injector is in an inoperative state. The downward force of the lower plunger 2 is provided by the lubricating oil pressure in the second elastic member 11 and the lubricating oil chamber 9, the preload force of the second elastic member 11 is usually small, the lubricating oil pressure in the lubricating oil chamber 9 and the injection chamber The fuel pressure in 8 can still be kept substantially equal.

The plunger injector also includes a limit device, which is set to define the lowest point of the downward movement of the upper plunger 3. The structure of the limit device is not limited. In order to simplify the structure, the limit device in this specific embodiment includes a limit protrusion 12 provided on the inner wall of the plunger hole or the upper plunger 3 and a limit protrusion 12 provided on the upper plunger 3 or column The inner wall of the plug hole is provided, and is provided as a limiting surface 13 which is in contact with the limiting protrusion 12. In this specific embodiment, the limit protrusion 12 is a limit stop ring provided on the inner wall of the plunger hole, and the lower end surface of the upper plunger 3 is the limit surface 13; or the middle or lower portion of the upper plunger 3 may also be used A step surface is formed, and this step surface serves as a limit surface 13. The limit stop ring is detachably installed in the groove on the inner wall of the plunger hole, and the limit stop ring may also be integrated with the inner wall of the plunger hole. In other embodiments, the limiting protrusion 12 may be provided on the upper end surface of the upper plunger 3, and the limiting surface 13 is a stepped surface provided on the inner wall of the plunger hole.

The limit device makes the upper plunger 3 continue to descend after descending to the lowest point of the downward movement, and the lower plunger 2 still continues to travel a small distance before reaching the lowest point of the downward movement of the lower plunger 2, so the lubricating oil chamber 9 The volume increases slightly, the pressure decreases, and the first check valve 10 opens to replenish the lubricating oil chamber 9 with the lubricating oil that leaked during the pumping process. The limit device can also effectively avoid the situation where the part where the upper plunger 3 and the plunger hole are precisely matched communicates with the lubricating oil inlet 7.

As shown in FIG. 1, an oil return chamber 14 is formed between the upper end of the upper plunger 3 and the inner wall of the plunger hole. The oil return chamber 14 is provided with a lubricating oil outlet, and a small annular gap from the upper plunger 3 and the plunger hole The trace amount of lubricating oil that oozes out can flow from the lubricating oil outlet back to the engine lubricating system.

The specific embodiment also provides an internal combustion engine, including the plunger injector.

The following briefly describes the working principle of the plunger injector provided in this specific embodiment in conjunction with FIG. 1:

When the high-pressure fuel enters the injection chamber 8 from the fluid inlet 5 to be injected, it will generate an upward thrust on the lower plunger 2. When the pressure exceeds the injection pressure of the injector, the lower plunger 2 overcomes the pre-preparation of the second elastic member 11 The tight force lifts upwards. At this time, the needle valve opens and the fuel is sprayed from the injection port 6 to atomize and start pre-injection. At the same time, because the lower plunger 2 is lifted upward, the pressure of the lubricating oil in the lubricating oil chamber 9 rises, and the lubricating oil in the lubricating oil chamber 9 pushes the upper plunger 3 to overcome the pretension of the first elastic member, and the needle The valve opening stroke is further increased, the fuel injection speed is accelerated, and the main injection stage is entered. Since the preload of the first elastic member is much greater than that of the second elastic member 11, the lubricating oil pressure in the lubricating oil chamber 9 and the fuel pressure in the injection chamber 8 are still substantially equal. When the pressure at both ends of the lower plunger 2 is equalized, and because the lower plunger 2 and the plunger hole are precisely matched, there is only a very small annular gap between the lower plunger 2 and the plunger hole, which can theoretically be guaranteed in the spray chamber 8 The pressure of the lubricating oil in the fuel and lubricating oil chamber 9 is balanced, leakage and mixing of lubricating oil and fuel will not occur, and the problem of leakage can be avoided while increasing the fuel injection pressure; at the same time, the lower plunger 2 is up and down During the movement, the lubricating oil remaining in the tiny annular gap between the lower plunger 2 and the inner wall of the plunger hole can ensure effective lubrication between the lower plunger 2 and the inner wall of the plunger hole.

At the end of the injection, the fuel pressure in the injection chamber 8 drops sharply. The first elastic member pushes the upper plunger 3 downward. The lubricating oil pressure in the lubricating oil chamber 9 and the elastic force of the second elastic member 11 jointly push the lower plunger 2 downward. Before the plunger 2 reaches the lowest point so that the needle valve closes, the limit stop ring abuts and prevents the upper plunger 3 from continuing to move downward, at this time, because the lower plunger 2 continues to move downward under the elastic force of the second elastic member 11 Run a small stroke to close the needle valve, the volume of the lubricating oil chamber 9 increases, the lubricating oil pressure decreases, and the low-pressure lubricating oil generated by the engine lubrication system can push the first check valve 10 from the lubricating oil inlet 7 into the lubricating oil chamber 9 , To replenish a small amount of lubricating oil lost due to trace leakage during fuel injection. A small amount of lubricating oil oozing from the tiny annular gap between the upper plunger 3 and the inner wall of the plunger hole can flow back to the engine lubrication system from the lubricating oil outlet.

Claims

A plunger injector includes:

A body (1), the body (1) is provided with a plunger hole, a fluid inlet (5) to be injected, an injection port (6), and a lubricating oil inlet (7);

A lower plunger (2) slidingly fitted in the plunger hole, the lower end of the lower plunger (2) is set to open or close the injection port (6);

A spray chamber (8) formed between the lower end of the lower plunger (2) and the inner wall of the plunger hole, the fluid inlet (5) to be sprayed and the spray port (6) are both provided as The spray chamber (8) is in communication;

The upper plunger (3) slidingly fits in the plunger hole;

A lubricating oil chamber (9) formed between the lower end of the upper plunger (3), the upper end of the lower plunger (2) and the inner wall of the plunger hole;

A first check valve (10), the lubricating oil inlet (7) is provided to communicate with the lubricating oil chamber (9) through the first check valve (10); and

The first reset device (4) is configured to provide a downward force to the upper plunger (3).
The plunger injector according to claim 1, further comprising a limiter device, the limiter device being arranged to define a lowest point of the downward movement of the upper plunger (3).
The plunger injector according to claim 2, wherein the limiting device includes a limiting protrusion (12) provided on the inner wall of the plunger hole or the upper plunger (3), and It is arranged on the inner wall of the upper plunger (3) or the plunger hole, and is arranged as a limiting surface (13) which is in contact with the limiting protrusion (12).
The plunger injector according to claim 3, wherein

The limit protrusion (12) is a limit stop ring provided on the inner wall of the plunger hole, and the limit surface (13) is the lower end surface of the upper plunger (3) or the limit position The surface (13) is a stepped surface provided in the middle or lower part of the upper plunger (3).
The plunger injector according to any one of claims 1 to 4, wherein the first resetting device (4) is located between the top end of the upper plunger (3) and the inner wall of the plunger hole The first elastic piece.
The plunger injector according to claim 5, further comprising a second elastic member (11) arranged to provide a downward force to the lower plunger (2).
The plunger injector according to claim 6, wherein the preload force of the first elastic member is greater than the preload force of the second elastic member (11).
The plunger injector according to any one of claims 1 to 4, further comprising an oil return chamber (14) formed between the upper end of the upper plunger (3) and the inner wall of the plunger hole, A lubricating oil outlet is provided on the oil return chamber (14).
The plunger injector according to any one of claims 1 to 4, further comprising a solenoid valve or a second one-way valve, and the fluid inlet (5) to be injected passes through the solenoid valve or the second one-way valve The valve communicates with the injection chamber (8).
An internal combustion engine including a plunger injector according to any one of claims 1 to 9.