CN207830020U - Fuel injector for engine and corresponding engine - Google Patents

Abstract

The utility model relates to a fuel injector (1) for an engine, comprising: a housing (2); a control oil chamber located in the housing (2); an oil return passage located in the housing (2); and A control valve located between the control oil chamber and the oil return passage, the control valve controls the fuel injection of the injector (1) by controlling the flow characteristics between the control oil chamber and the oil return passage; A local decompression area (75) suitable for reducing the amount of air bubbles in the fuel reaching the sealing area is configured at a position spaced from the sealing area of the control valve on the fuel flow path. It also relates to an engine comprising such an injector. According to the utility model, the "cavitation" of air bubbles on the sealing area can be reduced, the service life of the fuel injector is prolonged, and its reliability is improved.

Description

Injectors for engines and corresponding engines

technical field

The utility model relates to a fuel injector for an engine and an engine comprising the fuel injector.

Background technique

The common rail fuel supply system used by diesel engines mainly includes a high-pressure oil pump, a fuel injector, and a high-pressure common rail that connects the high-pressure fuel pump to the fuel injector. The fuel injector injects high-pressure fuel from the common rail into the combustion chamber of the diesel engine.

Existing fuel injectors generally include an elongated housing within which is mounted a control valve, usually a ball valve. A ball valve includes a seat and a ball core. The ball core is adjacent to the solenoid valve of the injector. The fuel injector has a fuel supply port formed in the housing. High-pressure fuel from the supply ports connected to the high-pressure common rail is distributed to the two fuel circuits of the injectors. An oil passage leads to the fuel injection cavity until the fuel injection port of the injector. Another oil passage leads to the control oil chamber, wherein the control oil chamber adjoins the valve seat of the ball valve. In the downstream direction of the ball valve, an oil return channel is provided in the housing.

The fuel injector also has a valve stem, one part of which is located in the control oil chamber, and the other part is located in the oil injection chamber. When the electromagnetic valve is not activated, the ball core seals the through hole of the valve seat, so that the oil return passage is isolated from the control oil chamber. In this case, the pressure of the control oil chamber acting on the valve stem is greater than the pressure acting on the valve stem of the oil injection chamber, so that the state of the valve stem tending to block the fuel injection port of the injector is maintained.

When the solenoid valve is activated, the high-pressure fuel from the oil supply port can lift the ball core, so that the high-pressure fuel enters the oil return passage from the control oil chamber, and finally flows back into the fuel tank, which will make the control oil The pressure in the cavity drops. In this way, the pressure in the fuel injection chamber will be greater than the pressure in the control oil chamber, so that the valve stem moves away from the fuel injection port, so that high-pressure fuel can be injected into the combustion chamber of the diesel engine in a controlled manner.

Usually, a throttling hole is provided in the through hole of the valve seat, a roughly cylindrical diffusion hole is provided downstream of the throttle hole, and a conical receiving section for receiving the ball core is provided downstream of the diffusion hole. A portion of the segment is intended to be in contact with a corresponding portion of the core to effect a seal. In operation, when the fuel flows through the orifice, a large number of air bubbles are generated, which cause so-called "cavitation" to the diffuser hole, the receiving section and the ball core-the high pressure will cause the bubble to burst, and the rupture will cause unevenness. The pressure will further impact the diffuser hole, the receiving section and the ball core, causing them to be damaged quickly, so that the control valve cannot achieve reliable sealing and affect the service life of the injector.

In order to reduce the impact of "cavitation" on the life of the injector, it is urgent to improve the control valve of the injector.

Utility model content

The purpose of this utility model is to provide an improved fuel injector to at least reduce the negative impact of "cavitation" phenomenon on the fuel injector.

According to one aspect of the present invention, a fuel injector for an engine is provided, comprising: a housing; a control oil chamber located in the housing; an oil return passage located in the housing; The control valve between the oil passages, the control valve controls the fuel injection of the injector by controlling the flow characteristics between the control oil chamber and the oil return passage; wherein, the seal between the fuel flow path and the control valve Localized pressure relief regions adapted to reduce the amount of air bubbles in the fuel reaching the sealing regions are configured at spaced apart locations.

According to an optional embodiment, the control valve includes a valve seat and a valve core adapted to cooperate with the valve seat; and/or the local decompression area is located downstream of the sealing area.

According to an optional embodiment, the valve seat includes a receiving section for receiving a valve core, the local decompression area is formed on the receiving section; and/or the valve core is spherical.

According to an optional embodiment, the local decompression area is configured as a groove, preferably an annular groove, and the annular groove is preferably arranged concentrically with the sealing area.

According to an optional embodiment, the cross section of the groove is triangular or arc-shaped.

According to an optional embodiment, the cross section of the groove is a right triangle, the valve seat has a through hole leading to the sealing area, and one right angle side of the right triangle is perpendicular to the axis of the through hole , the other right-angled side is parallel to the axis of the through hole.

According to another aspect of the present invention, an engine is provided, and the engine has the fuel injector.

According to the utility model, the "cavitation" caused by air bubbles to the sealing area can be reduced, the service life of the fuel injector is prolonged, and its reliability is improved.

Description of drawings

Below, by referring to the accompanying drawings to describe the utility model in more detail, the principle, characteristics and advantages of the utility model can be better understood. The attached drawings include:

Fig. 1 shows a fuel injector according to an exemplary embodiment of the present invention.

FIG. 2 shows a partially enlarged view of the fuel injector shown in FIG. 1 , wherein the control valve of the fuel injector is in an open state.

Fig. 3 shows the state when the control valve of the fuel injector shown in Fig. 2 is closed.

Detailed ways

In order to make the technical problems, technical solutions and beneficial technical effects to be solved by the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and several exemplary embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, rather than to limit the protection scope of the utility model.

Fig. 1 shows a fuel injector 1 according to an exemplary embodiment of the present invention. The fuel injector 1 comprises a generally elongated housing 2 . The housing 2 is provided with an oil supply port 3, which can be connected to a high-pressure common rail (not shown) via a joint 4 to receive high-pressure fuel from the high-pressure common rail. Two oil chambers are provided in the housing 2 . One is the control oil chamber and the other is the injection chamber.

A control valve, a solenoid valve 5 and a movable valve stem 6 are installed in the housing 2 . As shown in FIG. 1 , the control valve includes a valve seat 7 and a valve core 8 . One end of the valve stem 6 is adjacent to the valve seat 7 of the control valve in the control oil chamber, and the other end of the valve stem 6 controls the opening and closing of the oil injection port 9 via a needle valve. In the housing 2 , a supporting structure is provided at a place away from the valve seat 7 for supporting the valve stem 6 , so that the valve stem 6 can move longitudinally in the housing 2 smoothly. The valve stem 6 can drive the action of the needle valve, so that the valve stem 6 and the needle valve form a valve stem assembly, and the selective fuel injection of the injector 1 can be realized through the action of the valve stem assembly.

When the fuel injector 1 is assembled in place, the fuel injection port 9 leads to the combustion chamber of the diesel engine. The valve seat 7 of the control valve is adjacent to the control oil chamber, while the fuel injection chamber is adjacent to the fuel injection port 9 .

Usually, two oil passages are formed in the housing 2 . High-pressure fuel is supplied to the two oil passages via the fuel supply port 3, respectively. One oil passage is directly communicated with the control oil chamber, and the other oil passage is directly communicated with the injection chamber. That is to say, the high-pressure fuel from the fuel supply port 3 will always be supplied to the control oil chamber and the fuel injection chamber.

The spool 8 acts between the solenoid valve 5 and the valve seat 7 . An oil return channel is also provided in the housing 2, and the oil return channel is connected to the control oil chamber through a control valve, so that the control valve can selectively control the connection between the oil return channel and the control oil chamber. That is to say, the control valve is located between the oil return passage and the control oil chamber in the housing 2 .

As shown in FIG. 1 , the spool 8 is acted upon by springs 10 and 11 and associated actuating members 12 and 13 , wherein the actuating members are controlled by a solenoid valve 5 . The solenoid valve 5 is controlled, for example, by the electronic control unit of the diesel engine. When the solenoid valve 5 is in the unactivated state, under the action of the springs 10 and 11 and the related actuating parts 12 and 13, the valve core 8 abuts against the valve seat 7, so that the oil supplied to the control oil chamber from the oil supply port 3 The high-pressure fuel cannot flow through the control valve, so that the oil return channel and the control oil chamber are in an isolated state. In this case, the pressure of the control oil chamber on the valve stem 6 is greater than the pressure of the oil injection chamber on the valve stem 6, so that the valve stem 6 controls the needle valve to tightly seal the fuel injection port 9, and the fuel injector 1 Unable to inject fuel.

When the solenoid valve 5 is activated under the control of the electronic control unit, the force of the springs 10 and 11 acting on the valve core 8 via the actuating parts 12 and 13 decreases, and the high-pressure fuel in the control oil chamber can pass through the through hole of the valve seat 7. Pushing the spool 8 to move away from the valve seat 7 creates a gap between the spool 8 and the valve seat 7 . At this time, the high-pressure fuel will flow from the control oil chamber to the oil return passage, and then flow back into the fuel tank. In this way, the pressure in the control oil chamber will decrease, making the force on the valve stem 6 out of balance, that is, the pressure of the control oil chamber acting on the valve stem 6 becomes smaller than the pressure of the oil injection chamber acting on the valve stem 6, The valve stem 6 controls the needle valve to leave the fuel injection port 9, so that the high-pressure fuel can be smoothly injected into the combustion chamber of the diesel engine.

The electronic control unit can control the injection quantity of the injector according to the need by controlling the activation time and frequency of the solenoid valve 5 . According to the above description, it can also be considered that the solenoid valve 5, the springs 10 and 11 and the actuating members 12 and 13 constitute a solenoid valve assembly that controls the control valve. Obviously, this solenoid valve assembly is only exemplary, and other types of driving mechanisms can also be used.

FIG. 2 further shows a partial enlarged view of the fuel injector shown in FIG. 1 . As shown in FIG. 2 , according to an exemplary embodiment of the present invention, the control valve adopts a ball valve with line contact seal, that is, the spool 8 of the control valve is spherical. It can also be seen from FIG. 2 that the through hole of the valve seat 7 generally includes an orifice 71, a diffusion hole 72 located downstream of the orifice 71, and a receiving section 73 located downstream of the diffusion hole 72, wherein the diffusion hole 72 The diameter is larger than the diameter of the orifice 71 , and the receiving section 73 is conically open and suitable for receiving the spool 8 .

When the control valve is closed, a part of the spool 8 is in sealing contact with a corresponding part of the receiving section 73 , this part of the spool 8 is called the spool sealing area, and the corresponding part of the receiving section 73 is called the valve seat sealing area 74 . For the ball valve, the valve core 8 may rotate during operation, so the sealing area of the valve core may change at any time, while the position of the sealing area 74 of the valve seat remains unchanged. The area where the valve core and the valve seat are sealed during work is called the sealing area of the control valve.

When the control valve is open (the state shown in Figure 2), high-pressure fuel flows from the orifice 71 to the diffuser hole 72 and a large number of air bubbles will be generated, and these air bubbles will impact and corrode the surface of the valve core 8 and the receiving section 73, resulting in Unfavorable “cavitation” affects the sealing performance between the corresponding part of the valve core 8 and the valve seat sealing area 74 of the receiving section 73 .

After a lot of research, it is found that the impact force of the above-mentioned large number of air bubbles is mainly due to the sudden drop in fuel pressure caused by the conical receiving section 73, and this sudden drop in fuel pressure causes the air bubbles to quickly flow through the surface of the valve core 8 and/or Or receiving section 73, especially valve seat sealing area 74 to cause "cavitation".

When the control valve is closed, due to the low pressure generated by the instantaneous closure, the fuel downstream of the control valve may generate new bubbles or still entrain the previously produced unbroken bubbles, and will quickly move towards the valve core 8 and/or Or the valve seat seal area 74 backflow, these bubbles will also produce unfavorable "cavitation".

In other words, during the working process of the fuel injector, there will be various possibilities to cause air bubbles to "cavitate" the sealing area of the control valve, as shown in Figure 2, where the air bubbles are represented by small circles.

According to an exemplary embodiment of the present invention, a localized relief zone 75 is configured downstream of the valve seat sealing zone 74 . When the fuel containing air bubbles flows back toward the valve core 8 and/or the valve seat sealing area 74, due to the local low pressure generated by the local decompression area 75, the fuel containing air bubbles will not directly reach the valve core 8 and/or the valve seat sealing area 74 , but will first enter the partial decompression region 75 before reaching the valve core 8 and/or the valve seat sealing region 74 , as shown in FIG. 3 . Most of the air bubbles will shrink or burst in the local decompression area 75 , and the local decompression area 75 is away from the valve core 8 and/or the valve seat sealing area 74 . Thus, "cavitation" of the valve core 8 and/or the valve seat sealing area 74 by air bubbles is reduced.

According to a preferred exemplary embodiment of the present invention, as shown in FIG. 3 , the local decompression area 75 is formed by a groove opened in the receiving section 73 downstream of the valve seat sealing area 74 . Preferably, the groove 75 is annular, and more preferably, it is arranged concentrically with the diffusion hole 72 and also with the sealing area, as shown in FIG. 3 .

According to a further exemplary embodiment of the present invention, the groove 75 has a triangular cross section, preferably a right triangle shape. More preferably, one right-angled side of the right-angled triangle is perpendicular to the axis of the diffusion hole 72 , and the other right-angled side is parallel to the axis of the diffusion hole 72 . This construction is easy to process.

It is obvious to those skilled in the art that the shape of the groove is not limited thereto, but can be any suitable shape, such as an arc.

The formation of the local decompression region 75 by forming a recess on the receiving section 73 allows a direct implementation on existing injectors, which is simple and feasible.

In addition, the local decompression area is not limited to be set on the receiving section 73. For example, if the valve core 8 is fixed and cannot rotate during operation, a corresponding structure such as a concave hole can also be set on the valve core 8. Grooves are used to form localized relief areas, especially if the spool 8 is configured as non-spherical.

For those skilled in the art, the local decompression area can be set at any position and on any structure downstream of the sealing area of the control valve, as long as the amount of backflow air bubbles reaching the sealing area can be reduced.

Based on similar technical ideas, a local decompression area can also be constructed upstream of the valve seat sealing area 74 to reduce the amount of air bubbles generated in the fuel traveling to the valve core 8 and/or the valve seat sealing area 74 when the control valve is opened. For example, grooves can be formed in the walls of the diffusion holes 72 .

According to an exemplary embodiment of the present invention, the diffusion hole 72 has a length such that air bubbles in the diffusion hole 72 are broken before reaching the valve core 8 and/or the valve seat sealing area 74 . In this case, the amount of air bubbles reaching the valve plug 8 and/or the seat sealing area 74 is reduced, so that "cavitation" is also reduced.

The basic idea of the present invention is that by constructing a local decompression area at a position away from the sealing area of the control valve, especially at a position downstream of the sealing area, it is possible to reduce the pressure reaching the valve core 8 and/or the valve seat sealing area 74 The amount of air bubbles can be reduced, which can reduce the adverse "cavitation" of the critical parts of the control valve. Although the fuel injector has been described above as an example, the technical idea of the present utility model can also be applied to other applications with similar working conditions and requirements.

Moreover, other advantages and alternative embodiments of the present invention will be apparent to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative structures, and exemplary embodiments shown and described. On the contrary, those skilled in the art may make various modifications and/or substitutions without departing from the basic spirit and scope of the present invention.

Claims (10)

1. a kind of fuel injector (1) for engine, including：

Shell (2)；

Control oil pocket in shell (2)；

Drainback passage in shell (2)；And

Control valve between the control oil pocket and drainback passage, the control valve is by controlling the control oil pocket and returning The oil spout of flow behavior control fuel injector (1) between oily channel；

It is suitable for it is characterized in that, being configured at the position being spaced apart with the sealing area of the control valve in fuel flow path Reduce the localised area of reduced pressure (75) that the bubble in fuel oil reaches the amount of the sealing area.

2. fuel injector (1) as described in claim 1, which is characterized in that

The control valve includes valve seat (7) and the spool (8) suitable for coordinating with valve seat (7)；And/or

The localised area of reduced pressure (75) is located at the downstream of the sealing area.

3. fuel injector (1) as claimed in claim 2, which is characterized in that

The valve seat (7) includes for receiving the reception section of spool (8) (73), and the localised area of reduced pressure (75) is formed in institute It states in reception section (73)；And/or

The spool (8) is spherical shape.

4. fuel injector (1) as claimed in claim 3, which is characterized in that

The localised area of reduced pressure (75) is configured to groove.

5. fuel injector (1) as claimed in claim 4, which is characterized in that

The groove is configured to the annular groove around the sealing area.

6. fuel injector (1) as claimed in claim 5, which is characterized in that

The annular groove is disposed concentrically upon with the sealing area.

7. the fuel injector (1) as described in any in claim 4-6, which is characterized in that

The cross section of the groove is triangle or arc.

8. the fuel injector (1) as described in any in claim 4-6, which is characterized in that

The cross section of the groove is right angled triangle, and the valve seat (7) has the through-hole for leading to the sealing area, described straight One right-angle side of angle triangle is vertical with the axis of the through-hole, another right-angle side is parallel with the axis of the through-hole.

9. fuel injector (1) as claimed in claim 8, which is characterized in that

The through-hole has throttle orifice (71) and the diffusion hole (72) positioned at the throttle orifice (71) downstream, the diffusion hole (72) It is configured to so that the length that the bubble in diffusion hole (72) ruptures before reaching the sealing area.

10. a kind of engine, which is characterized in that the engine has any fuel injector (1) in claim 1-9.