KR102244948B1 - Fuel injection nozzle - Google Patents

Abstract

According to an aspect of the present invention, a fuel injection nozzle for injecting fuel into a combustion chamber of an internal combustion engine is provided. The nozzle has a nozzle body having a bore to receive fuel from a supply line for pressurized fuel. At least one injection opening is provided for transferring fuel from the bore to the combustion chamber, the at least one injection opening having a total cross-sectional area A _tot . Between a closed position in which the flow of fuel into the combustion chamber is prevented through the at least one injection opening and an injection position in which the flow of fuel into the combustion chamber is possible through the at least one injection opening, a needle is inserted in the bore. It can be displaced in the longitudinal direction. A restraint is provided for constraining fuel flow through the bore. The restraint is dimensioned as a function of the total cross-sectional area A _{tot of the at least one spray opening.}

Description

Fuel injection nozzle {FUEL INJECTION NOZZLE}

The present invention relates to a fuel injection nozzle, in particular a fuel injection nozzle for injecting fuel into a cylinder of an internal combustion engine.

EP 0 844 383 and EP 2 568 157 disclose high-pressure fuel injectors for internal combustion engines. The fuel injector has an injection nozzle forming a bore. The bore provides a flow path for high pressure fuel between the fuel inlet and the plurality of outlets, the fuel being received from the high pressure fuel supply passage. The fuel injector has a needle that is slidable within the bore. A needle seating is formed at the lower end of the bore, and the needle can be combined with the seating. The outlet is provided downstream of the seating, preventing fuel from being injected when the needle engages with the seating. When the needle is lifted from the seating, fuel can flow past the seating through the outlet and into the associated combustion chamber of the engine.

The needle has at least one downstream-facing thrust surface that acts to cause the high pressure fuel in the bore to provide a lifting force to the needle. A control chamber is provided in the injection nozzle at the upper end of the needle so that the upper end of the needle is exposed to the fuel pressure in the control chamber. The control chamber receives fuel at high pressure from the supply canister and is connectable to the low pressure drain by means of a valve. Thus, the valve controls the fuel pressure in the control chamber to determine the downward closing force acting on the upper end of the needle. Accordingly, the direction of the net hydraulic force acting on the needle and the opening and closing motion of the valve needle accordingly can be controlled.

Restriction, in the form of a small radial gap between the valve needle and a portion of the bore, is provided to constrain the fuel flow through the bore between the fuel inlet and outlet. The restraint is upstream of the thrust surface facing downstream. Thus, when the needle is opened to allow injection and communication between the control chamber and the drain and then the drain is closed to initiate the closure of the needle, the upward force acting on the downstream facing thrust surface due to the fuel pressure in the bore. Due to the fuel pressure in this control chamber, the restraint portion ensures that it is lower than the downward force acting on the upper end of the needle. The pressure difference resulting from the restraint portion causes a substantial net closing hydraulic force on the needle, allowing rapid needle closure to be achieved.

In at least certain embodiments, the present invention aims to overcome or at least ameliorate the drawbacks associated with known fuel injection nozzles. In particular, in at least a specific embodiment, the present invention is to provide a fuel injector nozzle with rapid needle closure and a controlled needle speed during the opening phase.

An aspect of the invention relates to a fuel injection nozzle, in particular a fuel injection nozzle for injecting fuel into a cylinder of an internal combustion engine.

According to another aspect of the present invention, as a fuel injection nozzle for injecting fuel into a combustion chamber of an internal combustion engine,

-A nozzle body having a bore to receive fuel from a supply line for pressurized fuel;

At least one injection opening for delivering fuel from the bore to the combustion chamber, the injection opening having a total cross-sectional area A _tot ; And

-In the bore between a closed position in which the flow of fuel into the combustion chamber is prevented through the at least one injection opening and an injection position in which the flow of fuel into the combustion chamber is possible through the at least one injection opening A fuel injection nozzle is provided comprising a needle displaceable in the longitudinal direction.

The fuel injection nozzle includes a constraining portion for constraining fuel flow through the bore. The restraint is dimensioned as a function of the total cross-sectional area A _{tot of the at least one spray opening.} The term “total cross-sectional area A _tot ” refers to the cumulative cross-sectional area of the at least one spray opening. In at least certain embodiments, the cross-sectional area of the injection opening can be varied along its length. The cross-sectional area of the at least one injection opening as described herein refers to the cross-sectional area measured at the outlet of the at least one injection opening, ie at the end of the at least one injection opening that opens into the combustion chamber.

의 함수인 수력 직경(D_hyd)을 갖고, 여기서, A_tot는 상기 적어도 하나의 분사 개구의 총단면적이다. 상기 함수는 선형 함수일 수 있다. 상기 구속부의 수력 직경의 상호 관계는 총 단면적의 선형 함수일 수 있다. 상기 선형 함수의 구배는

일 수 있으며, 여기서 a는 상수이고, L은 구속부의 종방향 길이이다.
The restraint part

_{Has a} hydraulic diameter (D hyd) that is a function of, where A _tot is the total cross-sectional area of the at least one injection opening. The function may be a linear function. The correlation between the hydraulic diameters of the restraints may be a linear function of the total cross-sectional area. The gradient of the linear function is

Where a is a constant and L is the longitudinal length of the constraint.

의 함수일 수 있으며, 여기서 b는 상수이고, L은 구속부의 종방향 길이이다. 상기 구속부의 수력 직경은 하기의 수학식을 따를 수 있다:
The relationship between the hydraulic diameter and the total cross-sectional area can be defined by an affine transformation. The affine transformation may include translation. The translation is

Can be a function of where b is a constant and L is the longitudinal length of the constraint. The hydraulic diameter of the restraint may follow the following equation:

Here, D _hyd is the hydraulic diameter, L is the longitudinal length of the restraint portion, A _tot is the total cross-sectional area of the at least one injection opening, and a and b are constants. The constant a may be in the range of 11.5 to 22, for example. The constant b may be, for example, in the range of 2 to 4.5.

The fuel injection nozzle may include an upstream region having an upstream section and a downstream region having a downstream section, and the upstream section is larger than the downstream section. The restraint portion may be disposed in the upstream region. Alternatively, the constraining portion may be disposed within the downstream region.

The restraint portion may be formed between the nozzle body and the flange. The restraint may be formed by a flange. The flange may be disposed on the needle. Alternatively, the flange may be disposed on the nozzle body.

The upper surface of the flange has a cross-sectional area perpendicular to the longitudinal central axis of the needle, and may be 200 to 800 times _{the total cross-sectional area A tot of the at least one injection opening.} The cross-sectional area of the flange may be 400 to 600 times _{the total cross-sectional area A tot of the at least one spray opening.} The cross-sectional area of the flange may be approximately 500 times _{the total cross-sectional area A tot of the at least one spray opening.}

The fuel injection nozzle may include a spring for pressing the needle toward the closed position. The needle may comprise an annular collar forming a spring seat for the spring. In addition, the annular collar may form the restraint portion. The restraint portion may be formed between the annular collar and the bore. In use, the fuel flow between the annular collar and the nozzle body can be constrained.

The annular collar may comprise a flange. The restraint portion may be formed between the nozzle body and the flange.

Alternatively or additionally, the annular collar may include one or more apertures to form the confinement for constraining the fuel flow. For example, the one or more holes may extend through the flange. Each of the holes may be in the form of a through bore extending through the flange. The flange may at least substantially form a seal by slidingly interlocking with the bore in the nozzle body. In this configuration, the annular collar forms a piston within the bore. Fuel flow from the supply line to the injection opening is through the one or more holes formed in the flange.

The annular collar may be integrally formed with the needle. Alternatively, the annular collar may be formed separately and mounted on the needle. For example, the annular collar may be press-fit on the needle.

According to another aspect of the present invention, as a fuel injection nozzle for injecting fuel into a combustion chamber of an internal combustion engine,

-A nozzle body having a bore to receive fuel from a supply line for pressurized fuel;

-At least one injection opening for delivering fuel from the bore to the combustion chamber;

-In the bore between a closed position in which the flow of fuel into the combustion chamber is prevented through the at least one injection opening and an injection position in which the flow of fuel into the combustion chamber is possible through the at least one injection opening A needle displaceable in the longitudinal direction; And

A spring for urging the needle toward the closed position

Including,

The needle is provided with a fuel injection nozzle comprising an annular collar forming a spring seat and a restraint for restricting fuel flow through the bore. Optionally, the constraining portion may be dimensioned as a function of the total cross-sectional area A _{tot of the at least one spray opening.}

The restraint portion may be formed between the annular collar and the bore. The annular collar may comprise a flange. The restraint portion may be formed between the nozzle body and the flange.

The annular collar may be integrally formed with the needle. Alternatively, the annular collar may be formed separately and mounted on the needle. For example, the annular collar can be press-fitted on the needle.

Alternatively or additionally, the flange may include one or more apertures defining the restraint. The one or more holes may extend through the flange. Each of the holes may be in the form of a through bore extending through the flange. The flange may at least substantially form a seal by slidingly interlocking with the bore in the nozzle body. In this configuration, the annular collar forms a piston within the bore.

According to another aspect of the invention, there is provided a fuel injector comprising a fuel injection nozzle of the type described herein.

Within the scope of this application, the various aspects, embodiments, examples and variations disclosed in the preceding paragraphs, claims and/or the following description and drawings, and in particular their individual features, may be taken independently or in any combination. Features related to one embodiment are applicable to all embodiments unless these features are incompatible.

One or more embodiments of the present invention will be described by way of example only with reference to the accompanying drawings.
1 is a longitudinal sectional view of a fuel injection nozzle according to a first embodiment of the present invention,
2 is a detailed view of the lower tip of the spray nozzle shown in FIG. 1;
3 is a cross-sectional view of a fuel injection nozzle according to an embodiment of the present invention,
Figure 4 is a graph of the relationship between the total cross-sectional area (A _tot ) and hydraulic diameter (D _{hyd) for different spray nozzles,}
5 is a longitudinal sectional view of a fuel injection nozzle according to a second embodiment of the present invention.

A fuel injection nozzle according to a first embodiment of the present invention will be described with reference to the accompanying drawings.

1 shows a fuel injection nozzle 1 according to an aspect of the invention. The illustrated injection nozzle 1 is configured for delivering fuel into a combustion chamber (not shown) of an associated internal combustion engine. The injection nozzle 1 has a specific application in a compression ignition engine (ie diesel engine), but the invention can be practiced in an injection nozzle 1 for a spark ignition engine (ie gasoline engine).

The terms "upper" and "lower" are used herein to describe the position relative to the features of the spray nozzle 1 and do not limit the scope of protection. The "lower" end of the injection nozzle 1 is the end disposed proximal to the combustion chamber (shown on the lower part of Fig. 1). Conversely, the "upper" end of the injection nozzle 1 is the end disposed distal to the combustion chamber (shown on the upper part of Fig. 1). Also, the terms "upstream" and downstream" are used herein with respect to the direction of fuel flow through the injection nozzle 1 and into the combustion chamber in normal use.

The spray nozzle 1 extends along the longitudinal axis XX'. The injection nozzle 1 comprises a nozzle body 3 and a bore 5 formed therein to receive fuel from a supply line for pressurized fuel. The injection nozzle 1 has a needle 7 which is displaceable in the bore 5 along the longitudinal axis XX'. The bore 5 has an enlarged upper region 9 communicating with a high pressure supply passage 11 for supplying fuel at high pressure. The needle 7 has a thrust surface 10 in the form of a truncated cone that is exposed to fuel pressure in the bore 5.

A needle seating 13 is formed at the lower end of the bore 5. The needle seating 13 has a truncated cone shape, and can be combined with the tip 14 of the needle 7. Downstream of the seating 13, the nozzle body 3 has a plurality of spraying openings 15 (of which it communicates with a sac volume 17 formed in the lowermost tip 19 of the bore 5). Only one is provided). The injection opening 15 allows the high-pressure fuel in the bore 5 to be injected into a combustion chamber (not shown) of an associated internal combustion engine. When the needle 7 is engaged with the seating 13, injection of fuel from the injection nozzle 1 into the combustion chamber is prevented. In this case, it can be said that the needle 7 is in the closed position. When the needle 7 is lifted away from the seating 13, the tip 14 of the needle 7 separates from the seating 13 and fuel is injected into the combustion chamber through the injection opening 15. In this condition, the needle 7 can be said to be in the injection position.

As shown in FIG. 1, the injection nozzle 1 includes a restraint 21 for constraining the fuel flow through the bore 5. The restraint 21 is formed with a restrictive pressure reduction element in the form of a flange 23 provided on the needle 7. The flange 23 is supported on the cylindrical shaft portion 25 of the needle 7. The flange 23 is annular and extends radially outward from the needle 7 and has a cross-sectional area larger than the average cross-sectional area of the rest of the needle. As will be described in more detail later, when the needle 7 is operably lifted from the seating 13, the flange 23 is through the bore 5 between the high pressure supply passage 11 and the injection opening 15. It causes a pressure drop in the fuel path.

The movement of the needle 7 is performed by controlling the fuel pressure in the control chamber. The needle 7 has a downstream end 29 (only the lower part of which is shown in Fig. 1). A spring (not shown) is provided to press the needle 7 toward the closed position. As the upstream end 29 of the needle 7 is received in the control chamber 27, the end face of the needle 7 is exposed to the fuel pressure in the control chamber 27.

The fuel pressure in the control chamber 27 is controlled by an operating system (not shown) familiar to a person skilled in the art. For example, the operating system may determine whether fuel flows from the high-pressure fuel supply passage 11 to the control chamber 27, while the fuel flow between the control chamber 27 and the low pressure drain is prevented, or the low pressure from the control chamber 27. It may be provided with a three-way valve that controls whether fuel can flow to the drain and whether fuel flow from the high pressure fuel supply passage 11 to the control chamber 27 is prevented. The operation of the three-way valve is controlled, for example by means of a solenoid or piezoelectric actuator. Alternatively, the three-way valve of the actuation system can be replaced with a two-way valve.

The nozzle body 3 has two separate portions, namely an upstream large diameter portion 31 and a downstream small diameter portion 35. The injection opening 15 is disposed at the end of the small diameter portion 35. More precisely, the injection opening 15 is disposed at the tip 39 of the small diameter portion 35 located in the combustion chamber of the engine (not shown) involved in use.

The bore 5 of the nozzle body 3 is formed into an upstream region 41 and a downstream region 43. The downstream region 43 has an inner diameter De. The needle 7 is formed coaxially through both the upstream and downstream regions 41 and 43 of the bore 5.

Fuel enters the bore 5 from the high-pressure fuel supply passage 11 through a fuel inlet 45 provided at the upper end of the upstream region 41 of the bore 5. The bore 5 forms a flow path from the fuel inlet 45, through the upstream region 41 and into the downstream region 43 and towards the injection opening 15. In use, the fuel fills both the upstream region 41 and the downstream region 43, together forming an accumulator volume for fuel.

A flange 23 is provided on the needle 7 in the region 43 downstream of the bore 5. The flange 23 has an annular shape and has a diameter Di smaller than the inner diameter De of the downstream region 43 of the bore 5 as shown in FIG. 3. Accordingly, the flange 23, together with the abutment 53 of the inner surface of the bore 5, is a restraint for restricting the fuel flow along the fuel flow path between the fuel inlet 45 and the injection opening 15 ( 21). The restraint 21 is formed around the outer peripheral surface of the flange 23 between the flange 21 and the abutment 53. Accordingly, the restraining portion 21 takes the form of an annular passage or gap. As will be described later, the dimensions of the restraint 21 are formed such that the needle 7 causes a pressure drop across the flange when fuel is flowing through the bore 5 in the injection position. Thereby, when the needle 7 is in the injection position, there is a reduced fuel pressure on the downstream side of the flange compared to the upstream side of the flange 21.

The dimensions of the restraining part 21 are formed as follows. The restraining part 21 has a hydraulic diameter D _hyd that can be defined by the following equation.

Here, A is a cross-sectional area of the restraint portion 21, and P is a wetted perimeter of the cross-section of the restraint portion 21. That is, the rim P is the periphery of the cross section of the constraining portion 21 that comes into contact with the fuel during use.

As shown in Fig. 3, the restraining portion 21 is an annular gap having an outer diameter equal to the inner diameter De of the downstream region 43 of the bore 5 and an inner diameter equal to the diameter Di of the flange. Thus, the hydraulic diameter is defined by the following equation:

The injection opening 15 has a total cross-sectional area A _tot . The total cross-sectional area A _tot of the injection opening 15 is defined herein as being the total area useful for fuel flow through the injection opening 15. That is, for a spray nozzle 1 having a plurality of spray openings, the total cross-sectional area A _tot is the sum of the cross-sectional areas of each spray opening. The cross-sectional area of the injection opening described herein refers to the cross-sectional area measured at the outlet of the injection opening, ie at the lower end of the injection opening that opens into the combustion chamber. In this embodiment, the restraint 21 is dimensioned as a function of _{the total cross-sectional area A tot of the injection opening 15.} The total cross-sectional area A _tot is fixed for a given spray nozzle 1. However, the total cross-sectional area A _tot may be different for different spray nozzles 1. For example, the total cross-sectional area A _tot may range from ^{0.05 to 0.15 mm 2} for different spray nozzles 1.

In this embodiment, the hydraulic diameter D _hyd of the restraint 21 is a function of the interrelationship of the total cross-sectional area A _tot. In particular, the hydraulic diameter (D _hyd ) is defined by the following equation.

의 값을 도시한다. 총 단면적(A_tot)의 각 값을 위해 그리고 상수 a 및 b의 각 값을 위해

의 상이한 값들은 도 4에 나타낸 음영 영역(shaded area)으로 나타낸다.
Here, D _hyd is the hydraulic diameter, L is the longitudinal length of the restraint portion, A _tot is the total cross-sectional area of the at least one injection opening, and a and b are constants. In this example, a is in the range of 11.5 to 22, and b is in the range of 2 to 4.5. Corresponding areas covered by the above equations having the above value ranges for a, b and A _{tot are shown in FIG. 4.} More precisely, Figure 4 as a function of the total cross-sectional area (A _tot) for a set of injectors of the type having a total cross-sectional area (A _tot) different from the range of 0.05 to 0.15 mm ² respectively,

Shows the value of For each value of the total cross-sectional area (A _tot ) and for each value of the constants a and b

The different values of are denoted by the shaded area shown in FIG. 4.

Thus, the flange 23 divides the accumulator volume into two separate pressure control volumes (hereinafter referred to as "bore volumes"). An upper bore volume 55 is formed between the upper end of the bore 5 and the flange 23, and a lower bore volume 57 is formed between the flange 23 and the seating 13. When the needle 7 is in the injection position, the fuel pressure in the upper bore volume 55 is greater than the fuel pressure in the lower bore volume 57 due to the restraint 21.

According to this embodiment of the present invention, the flange 23 is a component of the injection nozzle 1 separate from the needle 7. The flange 23 is not movable relative to the needle 7 as the flange is arranged to be press-fitted to the shaft portion of the needle 7. Thus, the flange moves with the needle 7 as the needle 7 slides within the bore 5. One advantage of manufacturing the flange separately from the needle 7 is that the bar size required to manufacture the needle 7 can be reduced, thereby reducing manufacturing costs and waste material during manufacturing. However, in a variant embodiment of the invention, the flange may be an integral feature of the needle.

The upper surface of the flange is arranged to have a cross-sectional area perpendicular to the longitudinal axis XX', and is 200 to 800 times, preferably approximately 500 times or more, of _{the total cross-sectional area A tot of the opening 15.} Providing this area ratio means that the needle 7 moves during closure at approximately the same speed as the fuel in the vicinity of the flange 23.

The operation of the spray nozzle 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

When the needle 7 is in the closed position, the tip 14 of the needle 7 engages with the seating 13 to prevent fuel flow out of the injection opening 15 in the combustion chamber. In this position, the high pressure fuel fills the regions 41 and 43 upstream and downstream of the bore 5. Since the fuel flow is obstructed, the pressure in the upper and lower bore volumes 55 and 57 on both sides of the flange 23 is the same. In this step, the communication between the control chamber 27 and the drain is closed, so that the fuel pressure in the control chamber 27 increases.

Thus, the combined downward or closing force acting on the needle 7 due to the fuel pressure in the control chamber 27 acting on the control piston 29 and the downward force provided by the spring are Due to the fuel pressure acting on the thrust surface 10, it is greater than the upward or opening force acting on the needle 7. This results in a net downward or closing force on the needle 7, so that the needle 7 is held in the closed position. As the fuel pressures in the upper and lower bore volumes 55 and 57 are the same, the upward and downward forces acting on the flange 23 due to the fuel pressure in the corresponding volume are balanced with each other.

To open the needle 7, a three-way valve is operated to open the connection between the control chamber 27 and the low pressure drain, thereby reducing the pressure in the control chamber 27. As the pressure in the control chamber 27 decreases, the resulting downward force acting on the upstream end 29 of the needle 7 decreases, as a result of which the needle ( The upward force applied on the thrust surface 10 of 7) reaches a point greater than the downward force acting on the needle 7 due to the fuel pressure in the control chamber 27 combined with the downward force due to the spring. do. At this point, the net upward or opening force acts on the needle 7 and the needle 7 is displaced upwardly away from the seating 13 toward the injection position.

As the needle 7 lifts off the seating 13, fuel begins to flow out of the opening 15 and into the combustion chamber. While the high-pressure fuel passage 11 continues to supply fuel to the bore 5, the pressure at the lower end of the bore 5 in the lower bore volume 57 decreases as fuel is injected into the combustion chamber. This helps to slow down the initial rate at which the needle 7 is lifted, since the upward pressure exerted by the fuel on the thrust surface 10 is reduced.

Further, since fuel flows through the flange 23 into the lower bore volume 57 and through the restraint 21, the fuel pressure in the lower bore volume 57 is the fuel pressure in the upper bore volume 55 Is reduced compared to.

As a result, the fuel pressure acting on each side of the flange 23 is no longer balanced, but instead the flange 23 applies a downward force on the needle 7. Thereby, the upper surface area of the flange 23 forms a thrust surface facing upstream that is exposed to the fuel pressure in the upper bore volume 55 to create a lower component force on the needle 7.

Thus, as the fuel flows through the bore 5, pressure is applied to the thrust surface facing upstream of the flange 23, whereby the needle 7 moves upwardly away from the seating 13 It helps to reduce the speed. Moreover, the movement of the flange 23 through the fuel causes a drag effect that weakens the speed of the needle 7. Accordingly, the flange 23 has an effect of damping the opening motion of the needle 7 with respect to the fuel in a direction opposite to the motion of the needle 7. Since the force of the lower component acting on the needle 7 through the flange 23 is not sufficient to overcome the force of the upper component acting through the thrust surface, the upward force of the net will continue to act to open the needle 7 do.

As a result, the needle 7 reaches its maximum lift position, and fuel continues to flow through the bore 5 and through the opening 15 from the high-pressure fuel passage into the combustion chamber.

When a predetermined amount of fuel is delivered to the combustion chamber, the valve is actuated to close the connection to allow the high pressure fuel to drain and flow into the control chamber 27. As the pressure in the control chamber 27 increases, the downward or closing force acting on the needle 7 through the upstream end 29 of the needle 7 increases. As a result, the combined downward directional force acting on the needle 7 exceeds the upward directional force acting on the needle 7 so that the net downward directional force causing the needle 7 to move in the closing direction is applied to the needle 7. Occurs in the phase.

As described above, since the restraint provides a pressure drop across the flange 23, there is a higher pressure in the upper bore volume 55 present in the lower bore volume 57 downstream of the flange 23. exist. The resulting downward force applied to the needle 7 through the flange 23 by the pressure of the fuel acting on the thrust surface facing upstream provides an additional closing force component that increases the closing speed of the needle 7 .

The closing action ends when the needle 7 engages the seating 13, preventing further fuel flow out of the opening 15 until another opening action is performed.

The effect of the restraint 21 on the movement of the needle 7 represents hysteresis. During the opening of the injection nozzle 1, the flange 23 damps the movement of the needle 7, allowing good control over a small injection volume. During the closing of the needle 7, the flange boosts the closing speed of the needle 7, allowing quick termination of the injection.

The longitudinal length (L) or thickness of the flange (23) taken in a direction parallel to the central axis of the needle (7) is relatively small compared to the diameter (Di) of the flange (23). A thin flange 23 is preferred in order to reduce the mass of the flange 23 and thus the moving mass of the needle 7.

In another embodiment, a point or localized constraint may be formed between the inner surface of the nozzle body and the edge of the flange. For example, the flange can be profiled to form a sharp or pointed outer edge.

5 shows a longitudinal cross-sectional view of a fuel injection nozzle 101 according to a second embodiment of the present invention. For the sake of clarity, similar reference numerals are used for similar elements, even if they are incremented by 100.

The injection nozzle 101 includes a nozzle body 103 and a bore 105 formed therein to receive fuel from a supply line for pressurized fuel. The injection nozzle 101 has a needle 107 that is movable along the longitudinal axis XX'. The high-pressure supply passage 111 supplies high-pressure fuel to the bore 105 for injection through the plurality of injection openings 115. The needle seating 113 is formed at the lower end of the bore 105 to cooperate with the tip 139 of the needle 107 to close the injection opening 115. When the needle 107 is engaged with the seating 113, injection of fuel from the injection nozzle 101 is prevented. When the needle 107 is lifted from the seating 113, the injection opening 115 is opened and fuel is injected.

The injection nozzle 101 includes a control chamber (not shown) for controlling the needle 107. A spring 159 is provided to urge the needle 107 towards the closed position. The spring 159 is a coil spring disposed around the needle 107. The annular collar 161 is fixedly mounted to the needle 107. The collar 161 forms a spring seat 162 for supporting the lower end of the spring 159. The annular flange 123 is formed by an annular collar 161 to confine fuel flow through the bore 105. The diameter Di of the flange 123 is substantially the same as the inner diameter De of the bore 105. The flange 123 is slidingly engaged with the sidewall of the bore 105 to at least substantially form a seal. A plurality of holes 163 are formed in the flange 123. The hole 163 in this embodiment is in the form of a plurality of bores extending through the flange 123 substantially parallel to the longitudinal axis XX' of the spray nozzle 101. The aperture 163 is operable to establish fluid communication past the annular collar 131.

In use, when the needle 107 is operatively lifted from the seating 113, a pressure drop is established under the flange 123. The holes 163 collectively form a hydraulic cross-sectional area equivalent to that formed by the constraining portion 121 in the first embodiment described herein. The hole 163 in the flange 123 may be configured such that the effective hydraulic cross-sectional area is a function of the total cross-sectional area A _{tot of the spray opening 115.} Between the hydraulic cross section of the total cross-sectional area (A _tot) it may be equal to the relationship of the hydraulic diameter (D _hyd) to the total cross-sectional area (A _tot) according to the first embodiment of the present invention.

The annular collar 161 forms a damping piston within the spray nozzle 101. By constraining the fuel flow past the annular collar 161, the hole 163 can reduce the lift (raise) speed of the needle 107. The opening speed of the needle 107 may be reduced due to hydraulic damping as the annular collar 161 moves through the fuel in the bore 105 and the pressure drop across the annular collar 161. The pressure drop occurs due to the depressurization under the annular collar 161, resulting in a net force in the direction toward the needle tip 139. The annular collar 161 provides a dual function of forming a spring seat 163 for the spring 159 and also forming an aperture 163 to control fuel flow in the bore 105.

In the second embodiment variant of the spray nozzle 101, the constraining portion 121 is an annular gap formed between the bore 105 and the flange 123. The restraining portion 121 has an outer diameter equal to the inner diameter De of the bore 105 and an inner diameter equal to the diameter Di of the flange 123. The injection opening 115 has a total cross-sectional area A _tot . The restraint 121 is dimensioned as a function of the total cross-sectional area A _{tot of the spray opening 115.} The hydraulic diameter (D _hyd ) of the constraining portion 121 is a function of the interrelationship of the total cross-sectional area (A _{tot ).} The relationship between the hydraulic diameter (D _hyd ) and the total cross-sectional area (A _tot ) is not changed from that defined in the first embodiment. In this configuration, the annular collar 161 provides a dual function of forming a spring seat 163 for the spring 159, and also forming a restraint 121 to control the fuel flow in the bore 105. .

Various changes and modifications can be made to the first and second embodiments of the spray nozzles 1 and 101 described herein. For example, any other suitable restraint may be provided, which may be formed at least partially by a flange or any other restraining element.

Alternatively, the spray nozzle may have a flange 23 comprising a recessed portion, the recess comprising a flat portion on its outer surface forming a constraining portion with the bore. A plurality of flat portions may be provided to avoid unbalanced loads on the flange and needle. In this variant, the annular edge of the flange is in sliding contact with the inner surface of the bore to allow free movement of the needle in the bore. In this case, fuel can flow only between the flat portion and the bore, and not around the entire circumference of the flange. In order to provide a number of restraints, a number of flats may be provided on the flange at angularly spaced positions. The flat portions may be arranged such that the total cross-sectional area provided by the plurality of restraints provides a predetermined total pressure drop across the flange. Any otherwise formed recesses or formations, such as one or more channels or grooves, may be used instead of or in addition to the flats.

In another variation, the restraint may be provided by an orifice in the flange in the form of one or more holes extending from the upper surface of the flange to the lower surface of the flange. In this configuration, the outer periphery of the flange can be arranged to provide a sliding fit with the inner surface of the bore to allow sliding movement of the needle in the bore. In this case, the fuel can only flow through the restraints and does not flow around the outer surface of the flange. Multiple orifices may be provided to form a plurality of restraints through the flange. The orifice may be provided in any shape or shape suitable to achieve the required functionality.

In another configuration, the recess may be provided in the nozzle body. The recess passes through the flange with the outer surface of the flange forming the confinement in the fuel flow path. Again, the outer surface of the flange is arranged to provide a sliding fit with the inner surface of the nozzle body, thereby allowing sliding movement of the needle in the bore area. Thereby, the fuel can only flow through the restraints and does not pass the rest of the outer surface of the flange. In yet another embodiment, an annular flow path may be provided around the periphery of the flange. Any suitable number of recesses may be provided. The recess may be manufactured by machining the nozzle body to form the recess, or by including the recess shape in a molding process for forming the nozzle body.

In addition, any other suitable means for providing a pressure drop across the constraining element may be used as a combination of different types of restraints. Again, the restraints are arranged such that the total cross-sectional area provided by the restraints provides a predetermined total pressure drop. A plurality of restraints may be disposed in succession in the fuel flow path through the injection nozzle. The flange may have two or more grooves formed circumferentially around its outer peripheral surface. The two grooves can form a plurality of protruding annular portions, which extend circumferentially around the flange.

Various changes and modifications may be made to the present invention without departing from the scope of the present application.

Claims (15)

In a fuel injection nozzle for injecting fuel into a combustion chamber of an internal combustion engine,
-A nozzle body having a bore to receive fuel from a supply line for pressurized fuel;
At least one injection opening for delivering fuel from the bore to the combustion chamber, the injection opening having a total cross-sectional area A _tot ; And
-In the bore between a closed position in which the flow of fuel into the combustion chamber is prevented through the at least one injection opening and an injection position in which the flow of fuel into the combustion chamber is possible through the at least one injection opening Needle that can be displaced in the longitudinal direction
Including,
The fuel injection nozzle includes a restricting portion for restricting fuel flow through the bore,
The constraining portion is dimensioned as a function of the total cross-sectional area (A _{tot) of the at least one injection opening,}
The restraint part

_{Has a} hydraulic diameter (D hyd) that is a function of,
Here, A _tot is the total cross-sectional area of the at least one injection opening,
The hydraulic diameter (D _hyd ) follows the following equation,

Where D _hyd is the hydraulic diameter, L is the longitudinal length of the restraint portion, A _tot is the total cross-sectional area of the at least one injection opening, and a and b are constants,
Fuel injection nozzle.
delete delete The method of claim 1,
The constant a is in the range of 11.5 to 22, the constant b is in the range of 2 to 4.5,
Fuel injection nozzle.
The method of claim 1,
And an upstream region having an upstream cross-section and a downstream region having a downstream cross-section,
The upstream cross-section is larger than the downstream cross-section, and the restraint portion is disposed in the upstream region,
Fuel injection nozzle.
The method of claim 1,
And an upstream region having an upstream cross-section and a downstream region having a downstream cross-section,
The upstream cross-section is larger than the downstream cross-section, and the restraint portion is disposed within the downstream region,
Fuel injection nozzle.
The method of claim 1,
The restraint portion is formed with a flange disposed in the bore so that the restraint portion is formed between the nozzle body and the flange,
Fuel injection nozzle.
The method of claim 7,
The flange is disposed on the needle,
Fuel injection nozzle.
The method of claim 7,
The flange is disposed on the nozzle body,
Fuel injection nozzle.
The method of claim 1,
The fuel injection nozzle includes a spring for pressing the needle toward the closed position,
The needle forms a spring seat and includes an annular collar forming the restraint portion,
Fuel injection nozzle.
The method of claim 10,
The annular collar includes a flange, and the restraint portion is formed between the nozzle body and the flange,
Fuel injection nozzle.
The method of claim 10,
The annular collar comprises one or more apertures to form the restraint portion,
Fuel injection nozzle.
The method of claim 12,
The annular collar comprises a flange, the one or more apertures extending through the flange,
Fuel injection nozzle.
The method of claim 10,
The annular collar is formed integrally with the needle or the annular collar is mounted on the needle,
Fuel injection nozzle.
A fuel injector comprising a fuel injection nozzle according to any one of claims 1 to 14.

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