JP6409068B2 - Fuel injection nozzle - Google Patents

Description

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

  EP 0 844 383 and EP 2568157 disclose high pressure fuel injectors for internal combustion engines. The fuel injector has an injection nozzle that forms a hole. This hole provides a flow path for high pressure fuel between the fuel inlet and the plurality of outlets. Fuel is received from the high pressure fuel supply path. The fuel injector includes a needle that can slide in the hole. A needle seat is formed at the lower end of the hole, and the needle can be engaged with the seat. The outlet is provided downstream of the seat so that fuel is prevented from being injected when the needle is engaged with the seat. When the needle is lifted from the seat, fuel can flow past the seat, through the outlet, and into the associated combustion chamber of the engine.

  The needle has at least one downstream-facing thrust surface. High pressure fuel in the hole acts on this thrust surface, and lift force is provided 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 high pressure fuel from the supply path. The control chamber can also be connected to a low pressure drain via a valve. Thus, the valve controls the pressure of the fuel in the control chamber and therefore determines the downward closing force acting on the upper end of the needle. In this way, the direction of the net hydraulic pressure acting on the needle (hence the opening and closing movement of the valve needle) can be controlled.

  A restriction (in the form of a small radial clearance between the valve needle and a portion of the hole) is provided to restrict the flow of fuel through the hole between the fuel inlet and outlet. The limiting portion is upstream of the thrust surface facing downstream. Thus, when the needle is opened to allow injection and then the communication between the control chamber and the drain is closed and the needle closed state is initiated, the downstream thrust due to the fuel pressure in the bore It is ensured that the upward force acting on the surface is less than the downward force acting on the upper end of the needle due to the fuel pressure in the control chamber. The differential pressure produced by the restriction allows a substantially net closing fluid pressure to act on the needle and allow rapid needle closure to be achieved.

  In at least some embodiments, the present invention aims to overcome or at least remedy the drawbacks associated with known fuel injection nozzles. In particular, in at least some embodiments, the present invention aims to provide a fuel injection nozzle that has a quick needle closing action and a controlled needle speed during the opening phase.

  Aspects of the present invention relate to a fuel injection nozzle, and more particularly to a fuel injection nozzle for injecting fuel into a cylinder of an internal combustion engine.

  According to a further aspect of the invention, a fuel injection nozzle is provided for injecting fuel into a combustion chamber of an internal combustion engine. The fuel injection nozzle includes a nozzle body having a hole for receiving fuel from a supply line for pressurized fuel; and at least one injection opening for supplying fuel from the hole to the combustion chamber, having a total cross-sectional area Atot A closed position in which the flow of fuel into the combustion chamber through the at least one injection opening is blocked; and the flow of fuel into the combustion chamber through the at least one injection opening. And a needle that can be displaced in the longitudinal direction within the hole.

  The fuel injection nozzle includes a restricting portion for restricting the flow of fuel through the hole. This restriction has a dimension as a function of the total cross-sectional area Atot of the at least one injection opening. The term total cross-sectional area Atot refers to the cumulative cross-sectional area of at least one injection opening. It will be appreciated that in at least some embodiments, the cross-sectional area of each of the injection openings or injection openings may vary along its length. The cross-sectional area of at least one injection opening as described herein is the cross-sectional area measured at the outlet of at least one injection opening, which is the combustion chamber of at least one injection opening. At the end of the opening.

  The limiting portion may have a hydraulic diameter that is a function of 1 / Atot. Here, Atot is the total cross-sectional area of at least one injection opening. This function may be a linear function. The inverse of the hydraulic diameter of the limiting portion may be a linear function of the total cross-sectional area. The slope of the linear function may be -a / L. Here, a is a constant, and L is the length in the longitudinal direction of the limiting portion.

  The relationship between hydraulic diameter and total cross-sectional area can be defined by affine transformation. An affine transformation may include a translation. The transformation can be a function of the inverse of the longitudinal length L of the restriction. The transformation can be a function of b / L. Here, b is a constant, and L is the length in the longitudinal direction of the limiting portion. The hydraulic diameter of the restriction can be according to the following formula:

  Where Dhyd is the hydraulic diameter, L is the length of the restriction in the longitudinal direction, Atot is the total cross-sectional area of at least one injection opening, and a and b are constants. The constant a can be set in the range of 11.5 to 22, for example. The constant b can be in the range of 2 to 4.5, for example.

  The fuel injection nozzle may include 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. The limiting unit may be disposed in the upstream region. In a variant, the restricting part may be arranged in the downstream region.

  The restricting portion may be formed between the nozzle body and the flange. The restricting portion may be formed by a flange. The flange may be disposed on the needle. In a variant, the flange may be arranged on the nozzle body.

  The upper surface of the flange may have a cross-sectional area perpendicular to the central longitudinal axis of the needle that is 200 to 800 times the total cross-sectional area Atot 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 Atot of the at least one injection opening. The cross-sectional area of the flange may be about 500 times the total cross-sectional area Atot of the at least one injection opening.

  The fuel injection nozzle may include a spring for biasing the needle toward the closed position. The needle may include an annular collar that forms a spring seat for the spring.

  Further, the annular collar may form a limiting portion. The limiting portion may be formed between the annular collar and the hole. In use, fuel flow between the annular collar and the nozzle body can be restricted.

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

  Alternatively or additionally, the annular collar may include one or more holes to form a restriction for restricting fuel flow. For example, the one or more holes may pass through the flange. Each of the holes may be in the form of a through hole that passes through the flange. The flange slidably cooperates with the hole in the nozzle body to at least substantially form a seal. In this configuration, the annular collar forms a piston within the hole. The flow of fuel from the supply line to the injection opening passes through one or more holes formed in the flange.

  The annular collar may be formed integrally with the needle. Alternatively, the annular collar may be formed separately and attached to the needle. For example, the annular collar may be press fit into the needle.

  According to a further aspect of the invention, a fuel injection nozzle is provided for injecting fuel into a combustion chamber of an internal combustion engine. The fuel injection nozzle includes a nozzle body having a hole for receiving fuel from a supply line for pressurized fuel; at least one injection opening for supplying fuel from the hole to the combustion chamber; and at least one injection opening. Displaceable longitudinally in the bore between a closed position where the flow of fuel through the combustion chamber is blocked and an injection position where fuel flow through the at least one injection opening is allowed into the combustion chamber And a spring for biasing the needle toward the closed position. The needle includes an annular collar forming a spring seat and a restriction for restricting fuel flow through the hole. The restriction may optionally have a dimension as a function of the total cross-sectional area Atot of the at least one injection opening.

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

  The annular collar may be formed integrally with the needle. Alternatively, the annular collar may be formed separately and attached to the needle. The annular collar may be press-fitted into the needle, for example.

  Alternatively or additionally, the flange may be provided with one or more holes to form a restriction. One or more holes may pass through the flange. Each of the holes may be in the form of a through hole that passes through the flange. The flange may slidably cooperate with the hole in the nozzle body. In this configuration, the annular collar forms a piston within the hole.

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

  Within the scope of the present application, the various aspects, embodiments, examples and alternatives described in the preceding paragraphs, the claims and / or the following description and drawings, in particular the individual features thereof, are independent. It is clearly conceivable that it can be implemented in any combination. Features described in connection with one embodiment are applicable to all embodiments as long as such features do not conflict.

  One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings.

1 shows a longitudinal section of a fuel injection nozzle according to a first embodiment of the present invention. FIG. 2 shows a detailed view of the lower end of the injection nozzle shown in FIG. 1 shows a cross section of a fuel injection nozzle according to an embodiment of the present invention. 3 shows a graphical representation of the relationship between hydraulic diameter Dhyd and total cross-sectional area Atot for various injection nozzles. 4 shows a longitudinal section of a fuel injection nozzle according to a second embodiment of the invention.

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

  A fuel injection nozzle 1 according to one aspect of the present invention is shown in FIG. The illustrated injection nozzle 1 is configured to supply fuel into a combustion chamber (not shown) of an associated internal combustion engine. Although the injection nozzle 1 has particular application in a compression ignition engine (ie, a diesel engine), the present invention may be implemented in an injection nozzle 1 for a spark ignition engine (ie, a gasoline engine).

  The terms “upper” and “lower” are used herein to describe the relative positions of the features of the injection nozzle 1 and do not limit the scope of protection afforded. Reference to the “lower” end of the injection nozzle 1 refers to the end located on the side closer to the combustion chamber (shown on the lower side of FIG. 1). Conversely, reference to the “upper” end of the injection nozzle 1 refers to the end (shown on the upper side of FIG. 1) located on the side far from the combustion chamber. Further, 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 injection nozzle 1 extends along the longitudinal axis XX '. The injection nozzle 1 includes a nozzle body 3 and a hole 5 formed in the nozzle body 3 for receiving fuel from a supply line for pressurized fuel. The injection nozzle 1 is provided with a needle 7. The needle 7 is displaceable along the longitudinal axis XX ′ in the bore 5. The hole 5 includes an enlarged upper region 9 that communicates with the high-pressure supply path 11. High-pressure fuel is supplied through the high-pressure supply path 11. The needle 7 is provided with a truncated cone-shaped thrust surface 10. The thrust surface 10 is exposed to the fuel pressure in the hole 5.

A needle seat 13 is formed at the lower end of the hole 5. The needle seat portion 13 has a truncated cone shape, and the tip 14 of the needle 7 can be engaged with the truncated cone shape. Downstream of the needle seat portion 13, the nozzle body 3 is provided with a plurality of injection openings 15 (only one of them is shown in FIGS. 1 and 2). The injection opening 15 is
It communicates with a sack volume 17 formed at the lowermost tip 19 of the hole 5. The injection opening 15 allows high pressure fuel in the hole 5 to be injected into the combustion chamber (not shown) of the associated internal combustion engine. When the needle 7 is engaged with the seat 13, fuel is prevented from being injected from the injection nozzle 1 into the combustion chamber. 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 seat 13, the tip 14 of the needle 7 is disengaged from the seat 13 and fuel is injected through the injection opening 15 into the combustion chamber. In this state, it can be said that the needle 7 is in the injection position.

  As shown in FIG. 1, the injection nozzle 1 includes a restricting portion 21 for restricting the flow of fuel through the hole 5. The restricting part 21 is formed with a restrictive pressure reducing element in the form of a flange 23 provided on the needle 7. The flange 23 continues to 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 larger cross-sectional area than the average cross-sectional area of the remaining portion of the needle. As will be described in more detail below, when the needle 7 is operatively lifted from the seat 13, the flange 23 causes a pressure drop in the fuel flow path through the hole 5 between the high pressure supply path 11 and the injection opening 15. Cause it to occur.

  The needle 7 is moved by controlling the fuel pressure in the control chamber 27. The needle 7 has an upstream end 29 (only the lower part of these is shown in FIG. 1). A spring (not shown) is provided to press the needle 7 toward the closed position. The upstream end 29 of the needle 7 is received in the control chamber 27, so that 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 actuation system (not shown) well known to those skilled in the art. For example, the actuation system may either allow fuel to flow from the high pressure fuel supply path 11 to the control chamber 27, or prevent fuel flow between the control chamber 27 and the low pressure drain, or allow fuel to flow from the control chamber 27. A three-way valve that can flow to the low-pressure drain and controls whether the flow of fuel from the high-pressure fuel supply path 11 to the control chamber 27 is blocked may be provided. The operation of the three-way valve is controlled by, for example, a solenoid or a piezoelectric actuator. In a variant, the three-way valve of the actuation system may be replaced with a two-way valve.

  The nozzle body 3 has two separate portions, that is, 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. The tip 39 is located in use in the combustion chamber (not shown) of the associated engine.

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

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

  The flange 23 is provided on the needle 7 in the downstream region 43 of the hole 5. As shown in FIG. 3, 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 hole 5. Therefore, the flange 23 together with the adjacent portion 53 of the inner surface 51 of the hole 5 forms a restricting portion 21 for restricting the flow of fuel along the fuel flow path between the fuel inlet 45 and the injection opening 15. The restricting portion 21 is formed around the outer peripheral surface of the flange 23 between the restricting portion 21 and the adjacent portion 53. Accordingly, the restriction 21 takes the form of an annular passage or clearance. As will be explained below, the size of the restriction 21 is such that when the needle 7 is in the injection position and fuel is flowing through the hole 5, a pressure drop across the flange occurs. . In this way, when the needle 7 is in the injection position, a fuel pressure that is reduced compared to the fuel pressure upstream of the flange 21 exists downstream of the flange.

  The dimension of the limiting part 21 is defined as follows. The limiting portion 21 has a hydraulic diameter Dhyd that can be defined by the following equation.

  Here, A is the cross-sectional area of the limiting portion 21, and P is the immersion side length of the cross section of the limiting portion 21. In other words, the immersion side length P is the circumferential length of the cross section of the limiting portion 21 that comes into contact with the fuel during use.

  As shown in FIG. 3, the limiting portion 21 is an annular gap, and has an outer diameter equal to the inner diameter De of the downstream region 43 of the hole 5 and an inner diameter equal to the flange diameter Di. Therefore, the hydraulic diameter is defined by:

The injection opening 15 has a total cross-sectional area Atot. The total cross sectional area Atot of the injection opening 15 is defined herein as the total area available for fuel flow through the injection opening 15. That is, for the injection nozzle 1 having a plurality of injection openings, the total cross-sectional area Atot is the sum of the cross-sectional areas of the respective injection openings. The cross-sectional area of the injection opening described herein is the cross-sectional area measured at the outlet of the injection opening. The outlet of the injection opening is at the lower end of the injection opening and opens into the combustion chamber. In the present embodiment, the restricting portion 21 has a dimension as a function of the total cross-sectional area Atot of the injection opening 15. The total cross-sectional area Atot is fixed for a given injection nozzle 1. However, it will be appreciated that the total cross-sectional area Atot may be different for the various injection nozzles 1. For example, the total cross-sectional area Atot may be in the range of 0.05 to 0.15 mm ² for each of various injection nozzles 1.

  In the present embodiment, the hydraulic diameter Dhyd of the limiting portion 21 is a function of the reciprocal of the total cross-sectional area Atot. Specifically, the hydraulic diameter Dhyd is defined by the following equation.

Here, Dhyd is the hydraulic diameter, and L is the length of the restricting portion 21 in the longitudinal direction. Atot is the total cross-sectional area of the injection opening 15, and a and b are constants. In the present embodiment, a is in the range of 11.5 to 22, and b is in the range of 2 to 4.5. Corresponding regions covered by the above equations having values in the above range for a, b, Atot are shown in FIG. More precisely, FIG. 4 shows the value of L / Dhyd as a function of the total cross-sectional area Atot for several types of injectors each having various total cross-sectional areas Atot ranging from 0.05 to 0.15 mm ² . Is shown. The various values of L / Dhyd for each value of the total cross-sectional area Atot and the various values for each value of the constants a and b are represented by the hatched portions shown in FIG.

  Thus, the flange 23 divides the accumulator volume into two separate pressure control volumes (hereinafter referred to as hole volumes). The upper hole volume 55 is formed between the top end of the hole 5 and the flange 23, and the lower hole volume 57 is formed between the flange 23 and the seat portion 13. When the needle 7 is in the injection position, the fuel pressure in the upper hole volume 55 becomes larger than the fuel pressure in the lower hole volume 57 due to the restriction unit 21.

  According to this embodiment of the invention, the flange 23 is a component of the injection nozzle 1 that is separate from the needle 7. The flange is configured to be press-fitted into the shaft portion of the needle 7, and as a result, the flange 23 cannot move with respect to the needle 7. Therefore, the flange moves with the needle 7 as the needle 7 slides in the hole 5. One advantage of manufacturing the flange separately from the needle 7 is that the size of the bar-like member required to manufacture the needle 7 can be reduced, thereby reducing manufacturing costs and waste material being manufactured. However, it will be appreciated that in alternative embodiments of the present invention, the flange may be integral with the needle.

  The top surface of the flange is configured to have a cross-sectional area perpendicular to the longitudinal axis XX 'that is 200 to 800 times larger (preferably about 500 times larger) than the total cross-sectional area Atot of the injection aperture 15. Providing this area ratio means that the needle 7 moves at approximately the same speed as the fuel near the flange 23 during closure.

  The operation of the injection nozzle 1 according to one embodiment of the present invention will be described with reference to FIGS.

  When the needle 7 is in the closed position, the tip 14 of the needle 7 engages with the seat 13 to block the flow of fuel out of the injection opening 15 in the combustion chamber. In this position, the high pressure fuel fills the upstream region 41 and the downstream region 43 of the hole 5. Since the fuel flow is blocked, the pressure in the upper hole volume 55 and the lower hole volume 57 on either side of the flange 23 is the same. At this stage, the communication between the control chamber 27 and the drain is closed, so that the fuel pressure in the control chamber 27 is high.

  As a result, 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 is the needle 7 Due to the pressure of the fuel acting on the thrust surface 10, the upward force acting on the needle 7, that is, the opening force becomes larger. This provides a net downward force or closing force on the needle 7, which remains in the closed position. Since the fuel pressure in the upper hole volume 55 and the lower hole volume 57 is the same, the upward force and the downward force acting on the flange 23 due to the fuel pressure in each volume are balanced with each other.

  In order to open the needle 7, the 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 and eventually the thrust surface of the needle 7 due to the fuel pressure in the lower bore volume 57. A point is reached where the upward force applied to 10 is 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. In this respect, a net upward force, i.e., an opening force, acts on the needle 7, and the needle 7 is displaced upward from the seat 13 toward the injection position.

  When the needle 7 is lifted from the seat portion 13, the fuel flows out from the opening 15 and starts to flow into the combustion chamber. The high-pressure fuel supply path 11 continues to supply fuel to the hole 5, but the pressure at the lower end of the hole 5 in the lower hole volume 57 decreases due to the fuel being injected into the combustion chamber. This helps to reduce the initial speed at which the needle 7 is lifted. This is because the upward pressure applied to the thrust surface 10 by the fuel decreases.

  Further, since the fuel flows over the flange 23 (and therefore through the restricting portion 21) and into the lower hole volume 57, the fuel pressure in the lower hole volume 57 is lower than the fuel pressure in the upper hole volume 55. As a result, the fuel pressure acting on each side of the flange 23 is no longer balanced, and instead the flange 23 applies a downward force on the needle 7. Thereby, the upper surface region of the flange 23 forms a thrust surface directed upstream. This thrust surface is exposed to the fuel pressure of the upper hole volume 55 and generates a downward force component acting on the needle 7.

  As a result, when the fuel flows through the hole 5, the fuel exerts pressure on the thrust surface facing the upstream of the flange 23. For this reason, it helps to reduce the speed at which the needle 7 moves away from the seat 13 and moves upward. Furthermore, a drag effect is produced by the movement of the flange 23 through the fuel. The speed of the needle 7 also decreases due to the drag effect. Therefore, the flange 23 has an effect of buffering the opening movement of the needle 7 against the fuel flow in the direction opposite to the movement of the needle 7. The downward force component acting on the needle 7 via the flange 23 is not sufficient to overcome the upward force component acting via the thrust surface, so that a net upward force will open the needle 7. Note that it continues to work.

  The needle 7 eventually reaches the maximum lift position and fuel continues to flow from the high pressure fuel path through the hole 5 and through the opening 15 into the combustion chamber.

  When the desired amount of fuel is supplied to the fuel chamber, the valve is operated to close the connection to the drain and allow high pressure fuel to flow to the control chamber 27. The pressure in the control chamber 27 increases, and as a result, the downward or closing force acting on the needle 7 via the upstream end 29 of the needle 7 increases. Eventually, the combined downward force acting on the needle 7 exceeds the upward force acting on the needle 7, resulting in a net downward force acting on the needle 7, which forces the needle 7 into the closed position. Moved to.

  As can be seen from the above, the limiting portion causes a pressure drop between the front and rear of the flange 23, so that the upper hole volume 55 has a higher pressure than the pressure present in the lower hole volume 57 downstream of the flange 23. The resulting downward force applied to the needle 7 via the flange 23 by the pressure of the fuel acting on the thrust surface facing upstream provides an additional component of the closing force, which component is the closing speed of the needle 7. Increase.

  This closing operation ends when the needle 7 engages the seat 13 and thereby prevents fuel from flowing out of the opening 15 until a further opening operation is performed.

  It will be appreciated that the effect of the restriction 21 on the movement of the needle 7 represents hysteresis. During the opening operation of the injection nozzle 1, the flange 23 cushions the movement of the needle 7 and enables good control of a small injection volume. While the needle 7 is closed, the flange increases the closing speed of the needle 7, which allows a quick stop of the injection.

  The longitudinal length L, that is, the thickness of the flange 23 along the direction parallel to the central axis of the needle 7 is relatively smaller than the diameter Di of the flange 23. A thin flange 23 is preferred to reduce the mass of the flange 23 (and thus the moving mass of the needle 7).

  In other embodiments, a limited point or location restriction may be formed between the inner surface of the nozzle body and the edge of the flange. For example, the flange may be shaped to form a sharp or pointed outer edge.

  FIG. 5 shows a longitudinal section of the fuel injection nozzle 101 according to the second embodiment of the present invention. Similar components are used for similar components, but have been increased by 100 for clarity.

  The injection nozzle 101 includes a nozzle body 103 and a hole 105 formed in the nozzle body 103 for receiving fuel from a supply line for pressurized fuel. The injection nozzle 101 is provided with a needle 107 that is movable along the longitudinal axis XX ′. The high pressure supply path 111 supplies high pressure fuel to the hole 105 for injection through the plurality of injection openings 115. The needle seat portion 113 is formed at the lower end of the hole 105 in order to close the injection opening 115 in cooperation with the tip 139 of the needle 107. When the needle 107 engages with the seat 113, fuel is prevented from being injected from the injection nozzle 101. When the needle 107 is lifted from the seat 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 toward the closed position. The spring 159 is a coil spring disposed around the needle 107. An annular collar 161 is fixedly attached to the needle 107. The annular collar 161 forms a spring seat 162 to support the lower end of the spring 159. An annular flange 123 is formed by an annular collar 161 to restrict fuel flow through the hole 105. The diameter Di of the flange 123 is substantially equal to the inner diameter De of the hole 105. The flange 123 slidably engages the side wall of the hole 105 and forms at least a substantially sealed portion. A plurality of holes 163 are formed in the flange 123. The holes 163 in the present embodiment are in the form of a plurality of holes that extend substantially parallel to the longitudinal axis XX ′ of the injection nozzle 101 through the flange 123. The hole 163 is operable to establish fluid communication beyond the annular collar 131.

  In use, when the needle 107 is operatively lifted from the seat 113, a pressure drop occurs below the flange 123. The hole portion 163 collectively forms a hydraulic cross-sectional area equivalent to that formed by the limiting portion 121 in the first embodiment described in this specification. The hole 163 of the flange 123 may be configured such that the effective hydraulic cross-sectional area is a function of the total cross-sectional area Atot of the injection opening 115. The relationship of the hydraulic cross-sectional area to the total cross-sectional area Atot may be equivalent to the relationship related to the hydraulic diameter Dhyd to the total cross-sectional area Atot according to the first embodiment of the present invention as defined herein.

  It will be appreciated that the annular collar 161 forms a buffer piston within the injection nozzle 101. By restricting the flow of fuel beyond the annular collar 161, the hole 163 can reduce the lift (rise) speed of the needle 107. The speed of the opening operation of the needle 107 can be reduced by a hydraulic buffer when the annular collar 161 moves through the hole 105 through the fuel, and a pressure drop across the annular collar 161. The pressure drop occurs due to the reduced pressure below the annular collar 161 that creates a net force in the direction toward the needle tip 139. The annular collar 161 can provide two functions: a function of forming a spring seat 163 for the spring 159 and a function of forming a hole 163 to control the flow of fuel in the hole 105. It will be understood.

  In the modification of the second embodiment of the injection nozzle 101, the restricting portion 121 is an annular gap formed between the hole 105 and the flange 123. The limiting part 121 has an outer diameter equal to the inner diameter De of the hole 105 and an inner diameter equal to the diameter Di of the flange 123. The ejection opening 115 has a total cross-sectional area Atot. The limiting part 121 has a dimension as a function of the total cross-sectional area Atot of the injection opening 115. The hydraulic diameter Dhyd of the limiting part 121 is a function of the reciprocal of the total cross-sectional area Atot. The relationship between the hydraulic diameter Dhyd and the total cross-sectional area Atot is not different from the relationship defined in this specification for the first embodiment. In this configuration, the annular collar 161 has two functions: a function of forming a spring seat 163 for the spring 159 and a function of forming a restriction 121 for controlling the flow of fuel in the hole 105. provide.

  It will be appreciated that various changes and modifications may be made to the first and second embodiments of the injection nozzle 1; 101 described herein. For example, any other suitable restriction may be provided and at least partially formed by a flange or any other suitable restriction element.

  In a variant, the injection nozzle may comprise a flange 23 having a recess. This recess has a flat portion on its outer surface that together with the hole forms a limiting portion. In order to avoid an unbalanced load acting on the flange and the needle, a plurality of flat portions may be provided. In this variation, the annular edge of the flange slidably contacts the inner surface of the hole so that the needle can move freely within the hole. In this case, the fuel can only flow between the flat and the hole, not around the entire circumference of the flange. In order to provide multiple limiting portions, multiple flat portions may be provided at a plurality of angularly spaced locations on the flange. This flat may be configured such that the total cross-sectional area provided by the multiple restrictors provides the desired total pressure drop across the flange. Instead of or in addition to the flat portion, any other shaped recess or structure (eg, one or more channels or grooves) may be used.

  In other variations, the restriction may be provided by a flange orifice in the form of one or more holes extending from the top surface of the flange to the bottom surface of the flange. In this configuration, the outer periphery of the flange may be configured to provide a sliding fit with the inner surface of the hole so that the needle can slidably move within the hole. In this case, the fuel can only flow through the restriction and cannot flow around the outer surface of the flange. Multiple orifices may be provided to form a plurality of restrictions through the flange. These orifices can be provided in any shape or form suitable to achieve the desired function.

  In other configurations, a plurality of recesses may be provided in the nozzle body. This recess forms, together with the outer surface of the flange, a restricting portion of the fuel flow path that exceeds the flange. Again, the outer surface of the flange is configured to provide a sliding fit with the inner surface of the nozzle body, and the needle can slide within the bore region. Thus, fuel can only flow through the restriction and cannot flow beyond the remainder of the outer surface of the flange. In other embodiments, an annular flow path may be provided around the outer surface of the flange. It will be appreciated that any suitable number of recesses may be provided. The recess may be manufactured by processing the nozzle body to form the recess, or by incorporating the recess shape into a casting process for forming the nozzle body.

  Any other suitable means for providing a pressure drop across the restriction element may be utilized, which may be a combination of different types of restriction. Again, the restriction is configured such that the total cross-sectional area provided by the restriction provides the desired total pressure drop. Multiple restrictions may be arranged in series 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 may form a plurality of protruding annular portions that extend circumferentially around the flange.

  It will be understood that various changes and modifications can be made to the present invention without departing from the scope of the application.

DESCRIPTION OF SYMBOLS 1,101 ... Fuel injection nozzle 3,103 ... Nozzle main body 5,105 ... Hole 7, 107 ... Needle 9 ... Enlarged upper area 10 ... Thrust surface 11, 111 ... High-pressure fuel supply path 13, 113 ... Needle seat 14 ... Tip DESCRIPTION OF SYMBOLS 15,115 ... Injection opening 17 ... Suck volume 19 ... Lowermost tip 21, 121 ... Restriction part 23 ... Flange 25 ... Cylindrical shaft part 27 ... Control chamber 29 ... Upstream end 31 ... Upstream large diameter part 35 ... Downstream small diameter part 39 , 139 ... tip 41 ... upstream area 43 ... downstream area 45 ... fuel inlet 51 ... inner surface 53 ... adjacent part 55 ... upper hole volume 57 ... lower hole volume 123 ... annular flange 131 ... annular collar 159 ... spring 161 ... annular collar 162 ... Spring seat 163 ... hole

Claims (13)

A fuel injection nozzle for injecting fuel into a combustion chamber of an internal combustion engine,
A nozzle body having a hole for receiving fuel from a supply line for pressurized fuel;
At least one injection opening for supplying fuel from the hole to the combustion chamber and having a total cross-sectional area (Atot);
A closed position in which a flow of fuel entering the combustion chamber through the at least one injection opening is blocked and a flow of fuel entering the combustion chamber through the at least one injection opening A needle that is displaceable in the longitudinal direction of the needle in the hole between the injection position and
The fuel injection nozzle, by generating a pressure drop in the fuel flow path through the hole, provided with a restriction portion for restricting the flow of fuel through said hole,
The restriction has a dimension as a function of the total cross-sectional area (Atot) of the at least one injection aperture;
The limiting portion has a hydraulic diameter (Dhyd) that is a function of 1 / Atot,
Atot is the total cross-sectional area of the at least one injection aperture;
The hydraulic diameter (Dhyd) is according to the following formula:

Dhyd is a hydraulic diameter, L is the length of the restriction in the longitudinal direction, Atot is the total cross-sectional area of the at least one injection opening, and a and b are constant fuel injection nozzles. The fuel injection nozzle according to claim 1,
The constant a is in the range of 11.5 or more and 22 or less,
The constant b is in the range of 2 or more and 4.5 or less. Fuel injection nozzle. The fuel injection nozzle according to claim 1 or 2,
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,
The restriction part is disposed in the upstream region. The fuel injection nozzle according to claim 1 or 2,
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,
The restriction part is disposed in the downstream region. Fuel injection nozzle. A fuel injection nozzle according to any one of claims 1 to 4,
The restricting portion is formed by a flange disposed in the hole, and as a result, the restricting portion is formed between the nozzle body and the flange. The fuel injection nozzle according to claim 5,
The flange is disposed on the needle. Fuel injection nozzle. The fuel injection nozzle according to claim 5,
The said flange is arrange | positioned at the said nozzle body Fuel injection nozzle. A fuel injection nozzle according to any one of claims 1 to 4,
The fuel injection nozzle includes a spring for biasing the needle toward the closed position;
The needle includes an annular collar that forms a spring seat and defines the restriction. Fuel injection nozzle. The fuel injection nozzle according to claim 8,
The annular collar includes a flange;
The restriction part is formed between the nozzle body and the flange. Fuel injection nozzle. The fuel injection nozzle according to claim 8,
The annular collar includes one or more holes for forming the restricting portion. Fuel injection nozzle. The fuel injection nozzle according to claim 10,
The annular collar includes a flange;
The one or more holes penetrate the flange. A fuel injection nozzle. The fuel injection nozzle according to any one of claims 8 to 11,
The annular collar is formed integrally with the needle or attached to the needle.   A fuel injector comprising the fuel injection nozzle according to any one of claims 1 to 12.

Images