CN108005826A - A kind of variable-frequency fuel-injection mouth - Google Patents

Abstract

The invention discloses a frequency conversion fuel injector, which belongs to the technical field of automotive engine fuel injectors, and comprises a fuel injector housing, a fuel injector head and a needle valve. The gap between the fuel injector housing and the needle valve forms a fuel injection nozzle cavity, the nozzle head is arc-shaped, the nozzle head is located at one end of the nozzle housing, the needle valve is tapered at the end where the nozzle head is located, and the tapered end of the needle valve is closely attached to the nozzle The connection between the nozzle housing and the fuel injection head, the fuel injection head is provided with a plurality of fuel injection holes; the inner surface of the fuel injection holes is alternately arranged with convex ribs extending along the axial direction of the fuel injection holes along its circumference and an inner groove, both of the ribs and the inner groove spirally extend along the axial direction of the oil injection hole; the inner groove is alternately arranged with protrusions and grooves along the extending direction of the inner groove. By optimizing the structure of the fuel injection nozzle, the present invention ensures that the oil is fully subjected to effective force, promotes turbulent flow, and has a good atomization effect of the oil; and the structure is simple and convenient for application.

Description

A variable frequency fuel injector

technical field

The invention relates to the technical field of automobile engine fuel injectors, in particular to a variable frequency fuel injector.

Background technique

With economic development, energy shortage and environmental pollution have become worldwide problems. How to further improve the efficiency of internal combustion engines, save fuel, and reduce emissions has become one of the important directions for the development of internal combustion engine technology. Today's automotive internal combustion engine technology mostly uses the characteristics of gasoline with low viscosity and fast evaporation, and mixes it with air to form a combustible mixture and spray it into the cylinder to make it easier to burn.

Nowadays, the fuel injection holes of vehicle fuel injectors mostly adopt the form of constant inner diameter and uniform inner surface friction coefficient. When the liquid flows on a uniform solid surface, for gasoline with a certain viscosity, laminar flow is likely to occur when the flow velocity is small, and turbulent flow occurs when the flow velocity is large; under the condition that other conditions remain unchanged, it is easy to occur when the diameter of the pipeline is small Laminar flow, large diameter is prone to turbulent flow. In the laminar flow state, the liquid in the tube is divided into an adsorption layer and a free layer, and the direction of the velocity flow field at different positions is along the axial direction, and the velocity has no radial component. In the adsorption layer, from the inner wall to the adsorption layer, when the gasoline droplets flow along the pores, the flow velocity gradually increases and changes in a gradient; in the free layer, the droplet flow velocity is the same. In turbulent flow, the velocity has a radial component. This process can be measured by the Reynolds number. Under the same flow rate, density, and pore size, the Reynolds number depends entirely on the viscosity of the fluid, that is, the ratio of inertial force to viscous force. When the Reynolds number increases to a certain extent, the droplet motion will change from laminar flow to turbulent flow, which can also be called turbulent flow. The larger the Reynolds number, the more irregular the internal movement, the easier it is to collide, and the more conducive to oil atomization. In fuel injection atomization, it is hoped to produce more intense turbulent flow movement, but increasing the diameter can promote turbulent flow, but at the same time it will cause the droplet to increase and reduce the atomization effect. Therefore, the automotive fuel injection system relies on high pressure to increase the flow rate. turbulence. Therefore, it is necessary to provide a simple fuel injector structure to improve the atomization effect of gasoline, reduce the high-pressure demand during gasoline atomization, and thereby reduce energy consumption.

The patent authorization announcement number is CN 105275698 B, which discloses a variable frequency fuel injector for an engine, which sets the inner surface of the fuel injection hole at the front end of the fuel injector into a uniform wave shape, so that the inner diameter of the fuel injection hole is cyclical along the axial direction. change; the inner surface of the oil injection hole is alternately set as a large friction coefficient area and a small friction coefficient area along the axial direction, so that the friction coefficient of the inner surface of the oil injection hole changes periodically along the axial direction. The Reynolds number of the oil is increased by changing the size of the inner diameter and the friction coefficient of the inner wall surface, so that the internal movement of the oil is violent, and the probability of molecular collision is increased to improve the effect of fuel atomization. But it still has disadvantages: because the inner surface of the oil injection hole is a uniform wavy structure, during the application process, the oil at the center flows directly from the inlet end of the oil injection hole to the outlet end in a straight line, and the oil around it flows along the The flow on the surface of the hole with periodic ups and downs in the inner diameter alternately gathers in the middle and diffuses to the periphery. However, at a certain moment, all the peripheral oils perform the same operation synchronously. The impact of the oil cancels each other out, so the impact on the center oil is small. This results in insufficient atomization of the oil in the middle. Moreover, when the oil flows in the oil injection hole of the above structure, there will be oil residue in the inner recess on the surface of the inner hole, and the injection of the oil is continuous during the injection time. Once there is more oil in the inner recess, Then the effect on the peripheral part of the flowing oil is weakened, and the team of the central oil is enlarged, that is, the insufficient atomized oil increases, further reducing the function of the injector.

Contents of the invention

1. Technical problems to be solved

The technical problem to be solved by the present invention is to provide a variable frequency fuel injector, which ensures that the oil is subjected to effective force in a relatively comprehensive way by optimizing the structure of the fuel injector, promotes turbulent flow, and has a good atomization effect of the oil; and the structure is simple , for easy application.

2. Technical solution

In order to solve the above problems, the present invention takes the following technical solutions:

A variable frequency fuel injector, comprising a fuel injector housing, a fuel injector head and a needle valve, the gap between the fuel injector housing and the needle valve forms a fuel injection cavity, the fuel injector head is arc-shaped, and the The fuel injection head is located at one end of the fuel injection nozzle housing, and the needle valve at the end where the fuel injection head is located is tapered, and the tapered end of the needle valve is closely attached to the connection between the fuel injection nozzle housing and the fuel injection head. The fuel injection head is provided with a plurality of injection holes; the inner surface of the injection hole is alternately arranged with ribs and inner grooves extending axially along the injection hole, and the ribs and The inner grooves extend spirally along the axial direction of the oil injection hole; the inner grooves are alternately arranged with bumps and grooves along the extending direction of the inner grooves.

As an improvement to the above solution, the cross-section of the rib is gradually narrowed from the side connecting the inner wall of the oil injection hole to the opposite side, and the side wall of the inner groove is located in the same plane as the side of the corresponding rib. The angle between the plane and the bottom of the inner groove is an obtuse angle. The inner grooves and convex ribs are arranged alternately and tightly, making full use of the inner surface of the oil injection hole, setting as many structures as possible to promote the internal movement of the oil, and more comprehensively acting on the oil flowing through the oil injection hole; the inner concave The width of the groove gradually widens from the bottom of the groove to the mouth of the groove, which facilitates the entry of oil, can act on more oil, and promotes turbulent flow.

As an improvement to the above solution, the included angle formed by the line between two adjacent transition points of the transition point of the spiral formed by the convex rib and the inner groove on the inner surface of the oil injection hole and the transition point is an obtuse angle. This design expands the pitch of the helical structure, and the radian of the convex ribs and the inner groove helix is small, which facilitates the oil to flow through the oil injection hole, reduces the oil residue, and reduces the overall impact on the oil during the flow process. Resistance, thereby reducing loss, avoiding a significant decrease in flow velocity, and ensuring turbulent flow.

As an improvement to the above solution, the protruding ribs are alternately arranged with protrusions 2 and grooves 2 along the extending direction of the protruding ribs. The oil flowing through the ribs is subjected to undulating force in the radial direction, which promotes turbulent flow.

As an improvement to the above solution, the outer surface of the part of the tapered end of the needle valve located in the fuel injection head is provided with threads. When the needle valve is opened, the oil enters the injector head at a high speed, and the oil around the outer surface of the needle valve flows along the thread, which initially creates the possibility of turbulent flow; at the same time, the center of the oil generates a driving force toward the periphery , to promote oil into the injection hole.

Further, the oil injection hole is located at the part where the oil injection head surrounds the periphery of the needle valve. Because if a fuel injection hole is set on the fuel injection head directly in front of the needle valve, more oil may be sprayed from the fuel injection hole, which is not conducive to the uniformity of fuel injection; When the thread works, the center of the oil can generate a driving force toward the periphery, and the oil injection hole is located at the part where the oil injection head surrounds the needle valve, which meets the oil flow direction requirements.

3. Beneficial effect

(1) In the present invention, the inner surface of the fuel injection hole is alternately arranged with ribs and inner grooves extending along the axial direction of the fuel injection hole along its circumference. extend. After the oil enters the injection hole, at any time, a part of the surrounding oil moves to the center under the action of the convex ribs, squeezing the center oil, while the other part moves to the periphery under the action of the inner groove, and the center The oil supplements the moving oil in this part to realize the alternating movement of the peripheral oil and the central oil; the spirally extending ribs and inner grooves promote the peripheral oil to flow in a spiral along the spiral structure, and the spiral peripheral oil Drive the oil in the center to undergo a spiral motion, and make the oil move in a radial direction all the time, so that the oil will have a turbulent flow, and the internal molecular movement will be violent, which increases the collision probability of molecules and promotes the fuel atomization effect.

(2) In the present invention, protrusions and grooves are alternately arranged on the inner groove along the extending direction of the inner groove. When the peripheral oil flows along the helical structure of the inner groove, it is subjected to fluctuating radial force, which promotes the radial fluctuation of the peripheral oil, thereby enhancing the interaction between the peripheral oil and the central oil, and further promoting the occurrence of turbulence. Flow, promote fuel atomization effect.

(3) The present invention only performs structural optimization on the inner surface of the oil injection hole and the outer surface of the tapered end of the needle valve, and has a simple structure and is convenient for application.

To sum up, the present invention optimizes the structure of the fuel injection nozzle to ensure that the oil is fully subjected to effective forces, promotes turbulent flow, and has a good atomization effect of the oil; and the structure is simple and easy to apply.

Description of drawings

Fig. 1 is a structural schematic diagram of a fuel injector;

Fig. 2 is a schematic view of the structure of the fuel injection hole 6 viewed from the port;

Fig. 3 is a schematic diagram of the structure after the section of the fuel injection hole 6 is expanded;

FIG. 4 is a schematic diagram of the spiral structure formed by the ribs 11 and the inner grooves 12 on the inner surface of the oil injection hole 6 .

Reference signs: 1-injection nozzle housing, 2-injection head, 3-needle valve, 4-injection cavity, 5-thread, 6-injection hole, 11-convex rib, 12-inner groove , 13-bump, 14-groove, 15-bump two, 16-groove two.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Example

As shown in Figure 1, a variable frequency fuel injector includes a fuel injector housing 1, a fuel injector head 2 and a needle valve 3, and the gap between the fuel injector housing 1 and the needle valve 3 forms a fuel injection chamber 4 , the fuel injection head 2 is arc-shaped, the fuel injection head 2 is located at one end of the fuel injection nozzle housing 1, the needle valve 3 is tapered at the end where the fuel injection head 2 is located, and the cone of the needle valve 3 is The end is closely attached to the junction of the fuel injector housing 1 and the fuel injector 2, and the fuel injector 2 is provided with a plurality of fuel injection holes 6; as shown in Figure 2 and Figure 3, the fuel injection holes The inner surface of 6 is alternately arranged with ribs 11 and inner grooves 12 extending axially along the injection hole 6 along its circumference, and the ribs 11 and inner grooves 12 are spirally arranged Extending; the inner groove 12 is alternately arranged with protrusions 13 and grooves 14 along the extending direction of the inner groove 12 .

In this embodiment, the cross section of the ribs 11 is gradually narrowed from the side connecting the inner wall of the oil injection hole 6 to the opposite side, and the side walls of the inner groove 12 are located on the same plane as the sides of the corresponding ribs 11 Inside, the angle between the plane and the bottom of the inner groove 12 is an obtuse angle. The inner grooves 12 and ribs 11 are arranged alternately and closely, the inner surface of the oil injection hole 6 is fully utilized, and as many structures as possible are set up to promote the internal movement of the oil, and the oil flowing through the oil injection hole 6 is more comprehensively affected. Liquid; the width of the inner groove 12 gradually widens from the bottom of the groove to the notch opening, which is convenient for the oil to enter, and can act on more oil to promote turbulent flow.

In this embodiment, as shown in FIG. 4 , the two adjacent transition points A and B of the spiral transition point C formed by the rib 11 and the inner groove 12 on the inner surface of the oil injection hole 6 are connected to the transition point C. The angle D _ACB formed by the line connecting C is an obtuse angle. Such a design expands the pitch of the helical structure, and the radian of the helix of the convex rib 11 and the inner groove 12 is small, which facilitates the flow of the oil through the oil injection hole 6, reduces the residual oil, and can reduce the friction during the oil flow process. The overall resistance is reduced, thereby reducing loss, avoiding a significant decrease in flow velocity, and ensuring turbulent flow.

In this embodiment, the convex ribs 11 are alternately arranged with protrusions 2 15 and grooves 2 16 along the extending direction of the ribs 11 . The oil flowing through the ribs 11 is subjected to undulating force in the radial direction, which promotes turbulent flow.

In this embodiment, threads 5 are arranged on the outer surface of the part where the tapered end of the needle valve 3 is located in the fuel injection head 2 . When the needle valve 3 is opened, the oil enters the injector head 2 at a relatively high speed, and the oil around the outer surface of the needle valve 3 flows along the thread 5, initially creating the possibility of turbulent flow; The surrounding driving force promotes the oil liquid to enter the oil injection hole 6.

In this embodiment, the oil injection hole 6 is located at the part where the oil injection head 2 surrounds the periphery of the needle valve 3 . Because if a fuel injection hole is set on the fuel injection head 2 directly in front of the needle valve 3, more oil may be sprayed from the fuel injection hole 6, which is not conducive to the uniformity of fuel injection; and as mentioned above, the needle valve 3 cone The screw thread 5 provided at the shaped end can generate a driving force from the center of the oil to the periphery when it acts, and the oil injection hole 6 is set at the position where the oil injection head 2 surrounds the needle valve 3, which meets the oil flow direction requirements.

The application process of the above variable frequency fuel injector is:

The needle valve 3 retreats, and the oil enters the interior of the injection head 2 from the oil injection chamber 4, and the oil around the outer surface of the needle valve 3 flows along the thread 5, initially creating the possibility of turbulent flow, and at the same time, the center of the oil flows to the periphery. The driving force promotes the oil to enter the oil injection hole 6; after the oil enters the oil injection hole 6, at any time, a part of the surrounding oil will move to the center under the action of the ribs 11, squeezing the center oil, and at the same time The other part moves to the periphery under the action of the inner groove 12, and the central oil replenishes the oil moved by this part to realize the alternating movement of the peripheral oil and the central oil; the spirally extending ribs 11 and the inner groove 12 Promote the spiral flow of peripheral oil along the spiral structure, and the peripheral oil of the spiral drives the central oil to undergo a spiral motion, which makes the oil always move radially more comprehensively, thereby causing turbulent flow of the oil; the peripheral oil flows through When the bump 13 and the groove 14 (or the second bump 15 and the second groove 16), they are subjected to fluctuating radial force, which promotes the radial fluctuation of the peripheral oil, thereby enhancing the interaction between the peripheral oil and the central oil. The effect of movement further promotes the occurrence of turbulent flow. Molecular movement inside the oil is violent, which increases the probability of molecular collision, so that the fuel is atomized more comprehensively and better, and then the atomized oil is sprayed out from the fuel injection hole 6 .

The detailed principle that the oil can be atomized through the oil injection hole 6 is as follows:

When oil with a certain viscosity flows on a uniform solid surface, laminar flow is likely to occur when the flow velocity is small, and turbulent flow occurs when the flow velocity is large; prone to turbulence. The fuel atomization effect can be measured by the Reynolds coefficient, that is, _Re = ρvd/μ, where ρ, v, and m are the density, flow velocity, and viscosity coefficient of the fluid, respectively, and d is the equivalent diameter of the injection hole. The larger the Reynolds number, the more irregular the internal movement, the easier it is to collide, and the more conducive to atomization. Under the same flow rate, density, and pore size, the Reynolds number depends entirely on the viscosity of the fluid, which is the ratio of inertial force to viscous force. Ribs and inner grooves are arranged on the inner surface of the fuel injection hole, and different regions have different adsorption capabilities for the fuel liquid column, so adhesion layers or adsorption layers of different thicknesses are formed on the inner wall of the fuel injection hole. When the oil flows along the injection hole, due to the change of the radial fluctuation of the adsorption layer, the radial motion in the droplet velocity flow field is increased, and the Reynolds number is increased; while the ribs and the inner groove are equipped with The bump and groove structure produces radial undulations, further increasing the Reynolds number. Molecular movement inside the droplet is more intense, increasing the frequency of molecular movement, so that it is easier to form turbulent flow movement, so under the same conditions, the atomization effect of fuel can be improved and the fuel atomization is easier.

As can be seen from the above, the present invention uses the Reynolds number to change the oil flow rate and internal pressure in the oil injection hole by using the spiral structure on the inner surface of the oil injection hole and the structure of bumps and grooves, so as to ensure that the oil is fully received. The effective force promotes turbulent flow and makes the internal molecular movement of the oil in the injection hole more intense, so as to increase the frequency of molecular movement, increase the probability of collision, and achieve better atomization effect. Compared with the traditional fuel injector, under the condition of achieving the same atomization effect, the frequency conversion fuel injector provided by the present invention can reduce the required atomization pressure, thereby saving energy consumption.

Those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present invention, rather than as a limitation to the present invention, as long as within the scope of the spirit of the present invention, the above-described embodiments Changes and modifications will fall within the scope of the claims of the present invention.

Claims (6)

1. a kind of variable-frequency fuel-injection mouth, including nozzle body (1), nozzle tip (2) and needle-valve (3), the nozzle body (1) with Gap forms fuel injection chamber (4) between needle-valve (3), and the nozzle tip (2) is arc, and the nozzle tip (2) is located at nozzle body (1) one end, one end where the needle-valve (3) is located at nozzle tip (2) is taper, and the tapering point of needle-valve (3) fit closely in The joining place of nozzle body (1) and nozzle tip (2), the nozzle tip (2) are equipped with multiple nozzle openings (6)；It is characterized in that, Nozzle opening (6) inner surface is alternately furnished with along nozzle opening (6) axially extending convex ribs bar (11) and inner groovy along its border (12), the convex ribs bar (11) and inner groovy (12) are along the rotating extension of nozzle opening (6) axial screw；Edge on the inner groovy (12) Inner groovy (12) extending direction is alternately furnished with convex block (13) and groove (14).

2. a kind of variable-frequency fuel-injection mouth according to claim 1, it is characterised in that the cross section of the convex ribs bar (11) is by even Connect that nozzle opening (6) inner wall one is tapered towards opposite face, the side wall of the inner groovy (12) and the side position of corresponding convex ribs bar (11) In in same plane, the angle between the plane and inner groovy (12) bottom is obtuse angle.

3. a kind of variable-frequency fuel-injection mouth according to claim 1, it is characterised in that the convex ribs bar (11) and inner groovy (12) The angle that line is formed between adjacent two transfer points and the transfer point for the spiral transfer point that nozzle opening (6) inner surface is formed For obtuse angle.

4. a kind of variable-frequency fuel-injection mouth according to claim 1, it is characterised in that along convex ribs bar on the convex ribs bar (11) (11) extending direction is alternately furnished with convex block two (15) and groove two (16).

5. a kind of variable-frequency fuel-injection mouth according to claim 1, it is characterised in that needle-valve (3) tapering point is located at oil spout The outer surface of part in head (2) is furnished with screw thread (5).

6. a kind of variable-frequency fuel-injection mouth according to claim 5, it is characterised in that the nozzle opening (6) is arranged on nozzle tip (2) It is looped around the position on needle-valve (3) periphery.