Fuel injector mounting structure

Abstract

Fuel injector mounting structure, wherein: a nozzle section (2) on a lower end section of a fuel injector (I), which is provided with a power supply coupling (14) projecting from a side face of the fuel injector (I), is inserted into an injector mounting hole (10) of an engine (E); a fuel supply sleeve (Da) of a fuel distribution tube (D) supported by the engine (E) is seated on a fuel inlet section (4) on the upper end section of the fuel injector (I); a retaining element (S) for biasing the fuel injector (I) to the injector mounting hole (10) is inserted between the fuel injector (I) and the fuel supply sleeve (Da), wherein a first contact surface (5) and a pair of second contact surfaces (6, 6) are formed in an intermediate section of the fuel injector (I), wherein the first contact surface (5) is orthogonal to the central axis (A) of the fuel injector (I) and is opposite the fuel supply sleeve (Da), wherein the paired second contact surfaces (6, 6) are opposite each other with a plane (C) between them, the plane (C) containing the central axis (A) and a center line (B) of the coupling (14), and the mounting element (S) comprises a base plate (15), an elastic piece (16) and a pair of rotation stop pieces (17, 17), wherein the base plate (15) sits on the first contact surface (5), the elastic piece (16) extends from the base plate (15) to come into elastic pressure contact with the fuel supply sleeve (Da) and bias the fuel injector (I) towards the injector mounting hole (10) by means of the reaction force generated by the pressure contact, wherein each rotation stop piece (17, 17) extends from the base plate (15) to come into contact with the second contact surface (6, 6) and limit rotation of the fuel injector (I) about the central axis (A), characterized in that each of the rotary stop pieces (17, 17) includes a vertical section (17a) which extends downwards from the corresponding outer side of the base plate (15), and a horizontal section (17b) which extends laterally from the lower end of the vertical section (17a), and the second contact surfaces (6, 6) are formed on an outer circumferential surface of a section (3) in the fuel injector (I) whose diameter is the largest, and the distance between the second contact surfaces (6, 6) is approximately equal to the largest diameter of the fuel injector (I).

Description

[0001] The invention relates to an improvement in a fuel injection valve support structure according to the preamble of claim 1, as known from JP 2010-168 965 A.

[0002] EP 2 221 469 A1 discloses a fuel injection valve support structure whose contact surfaces are formed on an outer peripheral surface of a portion of the fuel injection valve whose diameter is the largest.

[0003] A fuel injector support structure is known from JP 2004 - 245 168 AA. In this conventional fuel injector support structure, only a U-shaped leaf spring is inserted as a support element between a fuel injector and a fuel supply sleeve. For this reason, the fuel injector tends to rotate more or less around its central axis while the engine is running due to engine vibration. This rotation changes the direction in which the fuel is injected from the nozzle portion of the fuel injector and affects the fuel combustion condition in the engine.

[0004] The object of the invention is therefore to provide a fuel injection valve support structure which is capable of limiting rotation of the fuel injection valve about the central axis in a simple manner.

[0005] To achieve the object, a fuel injection valve support structure according to claim 1 is provided.

[0006] According to a first feature of the fuel injection valve support structure, a nozzle portion at a lower end portion of a fuel injection valve, which is provided with a power supply coupling projecting from a side surface of the fuel injection valve, is inserted into an injector mounting hole of an engine; a fuel supply sleeve of a fuel rail supported by the engine is fitted on a fuel introduction portion at the upper end portion of the fuel injection valve; and a support member for biasing the fuel injection valve toward the injector mounting hole is inserted between the fuel injection valve and the fuel supply sleeve, wherein a first contact surface and a pair of second contact surfaces are formed in an intermediate portion of the fuel injection valve,wherein the first contact surface is orthogonal to the central axis of the fuel injection valve and faces the fuel supply sleeve, wherein the pair of second contact surfaces face each other with a plane therebetween, the plane containing the central axis and a center line of the coupling, and the support member includes a base plate, an elastic piece, and a pair of rotation stop pieces, wherein the base plate sits on the first contact surface, the elastic piece extends from the base plate to come into elastic pressure contact with the fuel supply sleeve and bias the fuel injection valve toward the injector mounting hole by means of the reaction force generated by the pressure contact, wherein each rotation stop piece extends from the base plate to come into contact with the second contact surface and limit rotation of the fuel injection valve about the central axis.

[0007] With the first feature of the invention, when the support member is inserted between the first contact surface of the fuel injection valve and the fuel supply sleeve from an outer side of the fuel injection valve located on the opposite side from the coupling, the base plate sits on the first contact surface; the elastic piece comes into elastic pressure contact with a front end surface of the fuel supply sleeve; and the reaction force generated by the pressure contact presses the base plate against the first contact surface. For these reasons, the fuel injection valve can be elastically supported between and by the engine and the fuel supply sleeve, and therefore the fuel injection valve can be prevented from moving in the axial direction.Since the pair of rotation stoppers of the support member simultaneously contact the pair of second contact surfaces on the two sides of the fuel injection valve while sliding over the pair of second contact surfaces such that the pair of second contact surfaces are held between and by the pair of rotation stoppers, rotation of the fuel injection valve about its central axis can be prevented. Therefore, a direction in which fuel is injected from the nozzle portion can be stabilized.

[0008] According to a preferred second feature of the invention, the pair of rotation stopper pieces are provided with elasticity to cause the pair of rotation stopper pieces to elastically contact the pair of respective second contact surfaces.

[0009] With the second feature of the invention, since the pair of rotation stoppers comes into elastic pressure contact with the pair of second contact surfaces of the fuel injection valve, torsional vibration of the fuel injection valve can be prevented.

[0010] According to a third feature of the invention, the second contact surfaces are formed on an outer peripheral surface of a portion in the fuel injection valve whose diameter is the largest.

[0011] According to the third feature of the invention, since the second contact surfaces are formed on the outer peripheral surface of the portion having the largest diameter in the fuel injection valve, rotation of the fuel injection valve can be prevented by a relatively small contact force applied to the second contact surfaces by the rotation stopper pieces, and accordingly, the direction in which the fuel is injected from the nozzle portion can be better stabilized.

[0012] According to a preferred fourth feature of the invention, the base plate includes a U-shaped cutout that accommodates the fuel injection valve when the support member is attached to the fuel injection valve, a pair of the elastic pieces are arranged side by side with a gap, the fuel injection valve being accommodated by the gap, and an end portion of each of the rotation stopper pieces that is forward in a direction in which the support member is attached to the fuel injection valve is bent outward.

[0013] With the fourth feature of the invention, since the base plate is fitted on the first contact surface with the fuel introduction portion received by the U-shaped cutout in the central portion of the base plate, a larger area for disposing the base plate on the first contact surface can be ensured. Moreover, because the pair of elastic pieces extending from one end of the base plate come into elastic pressure contact with a front end surface of the fuel supply sleeve while the fuel introduction portion is received between the pair of elastic pieces, a reaction force generated by the pressure of the elastic pieces against the fuel supply sleeve can act on the fuel injection valve along the central axis of the fuel injection valve. Accordingly, the fuel injection valve can be stably supported without tilting.Furthermore, when the support member is mounted on the fuel injection valve, the outwardly curved end portion of each rotation stopper acts as a guide for guiding the corresponding second contact surface to a center portion of the rotation stopper. Accordingly, the center portion of each rotation stopper can be smoothly set to a predetermined position on the corresponding second contact surface. Furthermore, the sliding surface of the rotation stopper over which the second contact surface slides is smooth, thus preventing damage to the second contact surface.

[0014] According to a preferred fifth feature of the invention, a third contact surface parallel to the central axis is formed on an outside surface of the fuel supply sleeve, and a positioning piece for limiting a position of the support member around the central axis by contact with the third contact surface extends from the base plate.

[0015] With the fifth feature of the invention, when the positioning piece of the support member comes into contact with the third contact surface of the fuel supply sleeve, each rotation stop piece comes into contact with the corresponding second contact surface, and a position of the fuel injection valve about its central axis with respect to the fuel supply sleeve is limited. Accordingly, the position of the fuel injection valve can be stabilized.

[0016] The above and other objects, features and advantages of the invention will become more apparent from the detailed description of the preferred embodiment given below with reference to the accompanying drawings. Fig. 1 is a partially longitudinal sectional front view showing a fuel injection valve support structure for a multi-cylinder engine; Fig. 2 is an enlarged sectional view taken along line 2-2 in Fig. 1; Fig. 3 is a sectional view taken along line 3-3 in Fig. 2; and Fig. 4 is a perspective view independently showing a support member shown in the other drawings.

[0017] An embodiment of the invention will now be described with reference to the accompanying drawings.

[0018] As in the Fig. 1 and Fig. 2, first, a plurality of fuel injection valves I for injecting fuel to combustion chambers Ec of the plurality of cylinders and a fuel rail D configured to distribute fuel to the fuel injection valves I are mounted on a cylinder head Eh of a multi-cylinder engine E. Furthermore, a support member S is interposed between each fuel injection valve I and the fuel rail D to prevent the fuel injection valve I from being displaced in its axial direction or around a central axis A. A detailed description of this structure will be given below.

[0019] Each fuel injection valve I is formed of a cylindrical nozzle portion 2, an electromagnetic coil portion 3, and a fuel introduction portion 4, which are coaxially arranged from the front end to the rear end of the fuel injection valve I. When current is supplied to the electromagnetic coil element 3, the fuel injection valve I opens a valve within the nozzle portion 2 and injects the fuel introduced through the fuel introduction portion 4 from the fuel rail D into the corresponding combustion chamber Ec.

[0020] In the fuel injection valve 1, the outer diameters of the nozzle portion 2, the fuel introduction portion 4, and the electromagnetic coil portion 3 are larger in this order. Accordingly, the electromagnetic coil portion 3 has the largest outer diameter. A power supply coupling 14 integrally protrudes from a side surface of the electromagnetic coil portion 3. An annular sealing / damping member 8 in close contact with a front end surface of the electromagnetic coil portion is attached to the outer periphery of the nozzle portion 2. An O-ring 9 is attached to a sealing groove 4a in the outer periphery of the fuel introduction portion 4.

[0021] An annular and flat first contact surface 5 facing the fuel introduction portion 4 side is formed in a boundary portion between the electromagnetic coil portion 3 and the fuel introduction portion 4. A pair of flat second contact surfaces 6, 6, which oppose each other with a plane C therebetween, are formed in a cutout shape in an outer peripheral surface of the electromagnetic coil portion 3. In this regard, the plane C includes a center axis A of the fuel injection valve 1 and a center line B of the clutch 14.

[0022] Each cylinder head Eh is provided with: a fuel injection valve mounting hole 10 whose inner end is open to a ceiling surface of the corresponding combustion chamber Ec; and an annular recessed portion 11 surrounding an outer open end of the fuel injection valve mounting hole 10. In this portion, the fuel injection valve 1 is inserted into the fuel injection valve mounting hole 10, and the sealing / damping member 8 is housed in this recessed portion 11.

[0023] Further, the fuel rail D is arranged along the direction in which the plurality of cylinders of the engine E are arranged. Fuel is supplied under pressure from one end of the fuel rail D by means of a pump (not shown). A plurality of fuel supply caps or sleeves Da, which are arranged coaxially with the plurality of fuel injection valves I fitted in the plurality of injection valve mounting holes 10, protrude toward one side surface of the fuel rail D. Each fuel supply sleeve Da is fitted onto the outer periphery of the fuel introduction portion 4 of the corresponding fuel injection valve I. Here, the O-ring 9 is in close contact with an inner peripheral surface of the fuel supply sleeve Da. A flat third contact surface 7, which is parallel to the central axis A of the corresponding fuel injection valve I, is formed on an outer surface of each fuel supply sleeve Da.A bracket Db is fixedly provided at a base portion of each fuel supply sleeve Da. The bracket Db is fixedly attached to a support column 12 with a bolt 13, the support column 12 being provided upright on a top surface of the cylinder head Eh.

[0024] As in the Fig. 2 to 4, the support element S is pressed from sheet steel and includes a base plate 15, elastic pieces 16, rotation stop pieces 17 and a positioning piece 18.

[0025] The base plate 15 is inserted while overlapping the first contact surface 5. A U-shaped cutout 19 for receiving the fuel supply portion 4 of the fuel injection valve I is provided in the central portion of the base plate 15. The pair of elastic pieces 16 configured to elastically press-contact a front end surface of the corresponding fuel supply sleeve Da are formed in one end of the base plate 15 located on the opposite side from the U-shaped cutout 19 so as to be integrally connected. The two elastic pieces 16 are arranged with a gap capable of receiving the fuel introduction portion 4 of the corresponding fuel injection valve I therebetween.

[0026] Each elastic piece 16 is formed of: a first elastic portion 16a extending upward from one end of the base plate 15 and bent like the horizontally lying letter U; and a second elastic portion 16b extending toward the other end of the base plate 15 while being curved upward from the first elastic portion 16a, with its end portion 16ba being brought into pressure contact with an upper surface of the base plate 15. A curvature radius R2 of the second elastic portion 16b is made sufficiently larger than the curvature radius R1 of the first elastic portion 16a (see Fig. 4).

[0027] While each elastic piece 16 is exposed, a distance L1 (see Fig. 4) from the apex of the second elastic section 16b to the underside of the base plate 15 is made larger than a distance L2 (see Fig.2) from the first contact surface 5 to the front end surface of the fuel supply sleeve Da. For this reason, once the base plate 15 and the elastic pieces 16 are interposed between the first contact surface 5 and the fuel supply sleeve Da, each elastic piece 16 can come into elastic pressure contact with the front end surface of the fuel supply sleeve Da while the first and second elastic portions 16a, 16b are bent. While the first and second elastic portions 16a, 16b are bent, the end portion 16ba of the corresponding second elastic portion 16b is slidable over the top of the base plate 15. The end portion 16ba is formed with an upward curve to enable smooth sliding.

[0028] The pair of rotation stoppers 17 are integrally formed with two outer surfaces of the base plate 15. Each rotation stopper 17 is formed in the shape of a downwardly inverted letter T and includes: a vertical portion 17a extending downwardly from the corresponding outer surface of the base plate 15; and a horizontal portion 17b extending from the lower end of the vertical portion 17a along the U-shaped cutout 19. The pair of rotation stoppers 17 is capable of holding the electromagnetic coil portion 3 between and through the pair of rotation stoppers 17 while bringing their horizontal portions 17b into contact with the respective second contact surfaces 6.Roots of the respective vertical portions 17a are elastic to bias the horizontal portions 17b inward, so that the pair of rotation stoppers 17 elastically holds the electromagnetic coil portion 3 therebetween by the pair of rotation stoppers 17. Furthermore, two end portions 17ba of each horizontal portion 17b are curved outward.

[0029] Furthermore, the positioning piece 18, which projects vertically upward from a gap between the pair of elastic pieces 16, is integrally connected to one end of the base plate 15. The positioning piece 18 is contactable with the third contact surface 7 of the fuel supply sleeve Da.

[0030] The functions of the versions are described below.

[0031] When the fuel injection valves I are mounted on the engine E, first, the fuel supply sleeves Da of the fuel rail D are fitted onto the fuel introduction portions 4 of the respective fuel injection valves I. Then, an assembled body including the fuel rail D, the fuel injection valves I, and the support members S is constructed by inserting each support member S between the first contact surface 5 of the corresponding fuel injection valve I and the corresponding fuel supply sleeve Da from the outer side of the fuel injection valve I, which is on the opposite side from the coupling 4, while an opening portion of the U-shaped cutout 19 of the corresponding base plate 15 is forward.

[0032] Next, the nozzle portions 2 of the fuel injection valves I of the assembled body are inserted into the respective injector mounting holes 10 of the cylinder head Eh. The sealing / damping members 8 are received in close contact with the front end surfaces of the electromagnetic coil portions 3 in the respective recessed portions 11. Next, the brackets Db are firmly attached to the support pillars 12 of the cylinder head Dh with the bolts 13, while adding a compression load to the respective support members S.

[0033] In each support member S, the base plate 15 is placed on the first contact surface 5, with the fuel introduction portion 4 of the fuel injection valve I received by the U-shaped cutout 19, and at the same time, the pair of elastic pieces 16 brings the vertices of the second elastic portions 16b into elastic pressure contact with the front end surface of the fuel supply sleeve Da by bending the first and second elastic portions 16a, 16b while receiving the fuel introduction portion 4 between the elastic pieces 16. A reaction force generated by the contact pressure presses the base plate 15 against the first contact surface 5. Thus, the fuel injection valve I is elastically held between and by the cylinder head Eh and the fuel supply sleeve Da, with the support member S and the sealing / damping member 8 interposed between the cylinder head Eh and the fuel supply sleeve Eh.

[0034] Furthermore, because the base plate 15 is fitted on the first contact surface 5 with the fuel introduction portion 4 received by the U-shaped cutout 19 being located in the central portion of the base plate 15, a larger area for disposing the base plate 15 on the first contact surface 5 can be ensured. Furthermore, because the pair of elastic pieces 16 extending from one end of the base plate 15 elastically contact the front end surface of the fuel supply sleeve Da while the fuel introduction portion 4 is sandwiched between the pair of elastic pieces 16, the reaction force generated by the pressure of the elastic pieces 16 against the fuel supply sleeve Da can act on the fuel injection valve I along the central axis A of the fuel injection valve I. Accordingly, the fuel injection valve I can be stably held without tipping.

[0035] The support member S is inserted into the gap between the first contact surface 5 and the fuel supply sleeve Da until the fuel introduction portion 4 comes into contact with an inner end of the U-shaped cutout 19. During insertion, while sliding over the second contact surfaces 6 of the two sides of the electromagnetic coil portion 3, the horizontal portions 17b of the pair of stopper pieces 17 of the support member S are in elastic contact with the second contact surfaces 6 thereof, such that the second contact surfaces 6 are held between and by the horizontal portions 17b. In this regard, since the two end portions 17ba of each rotation stopper piece 17 are each formed in an outwardly curved shape, the outwardly curved surfaces of the two end portions 17ba perform a guiding function for guiding a corresponding second contact surface 6 to a central portion of the horizontal portion 17.For this reason, the center portions of the horizontal portions 17b can be smoothly moved to predetermined positions on the respective second contact surfaces 6. Moreover, the sliding surfaces of the horizontal portions 17b over which the second contact surfaces 6 slide are smooth, and therefore do not cause damage to the second contact surfaces 6. Furthermore, when the support member S is removed from the fuel injection valve I, the two end portions 17ba of each horizontal portion 17b also do not cause damage to the corresponding second contact surfaces 6. Moreover, because the horizontal portions 17b come into pressure contact with the second contact surfaces 6 due to the elasticity of the vertical portion 17a, torsional vibration of the fuel injection valve can be prevented.

[0036] In addition, because the pair of rotation stopper pieces 17 comes into contact with the pair of second contact surfaces 6 formed on the outer periphery of the electromagnetic coil portion 3 whose diameter is largest in the fuel injection valve 1, rotation of the fuel injection valve 1 can be prevented by means of a relatively small contact force, and accordingly, the direction in which the fuel is injected from the nozzle portion 2 can be stabilized.

[0037] When the fuel introduction portion 4 comes into contact with the inner end of the U-shaped cutout 19, the positioning piece 18 of the support member S comes into contact with the third contact surface 7 of the fuel supply sleeve Da at approximately the same time. This contact and the contact of the rotation stop pieces 17 with the respective second contact surfaces 6 limit the position of the fuel injection valve I around the central axis A of the fuel injection valve with respect to the fuel supply sleeve Da. Accordingly, the position of the fuel injection valve I becomes stable.

[0038] Furthermore, each elastic piece 16 is formed of: the first elastic portion 16a, which is connected to one end portion of the base plate 15 and has a smaller radius of curvature R1; and the second elastic portion 16b, which extends from the first elastic portion 16a, forms the end tip portion 16ba, which comes into sliding contact with the upper surface of the other end portion of the base plate 15, and has the larger radius of curvature R2. For this reason, the second elastic portion 16b is supported by the base plate 15 via both the end tip portion 16ba and the first elastic portion 16.Accordingly, although the first elastic portion 16a may deform (generally, a portion curved with a small radius of curvature tends to be easily plastically deformed), the elastic force of the second elastic portion 16b maintains the biasing function of each elastic piece 16 to bias the fuel supply sleeve Da. Moreover, because the radius of curvature R2 of the second elastic portion 16b is made larger than the radius of curvature R1 of the first elastic portion 16a, the height of each elastic piece 16 is minimized as much as possible, and the support member S can be easily installed in the narrow space between the first contact surface 5 and the fuel supply sleeve Da.

[0039] The invention is not limited to the above-described embodiment. Various design changes may be made within the scope that does not deviate from the spirit of the present invention. For example, the invention can be applied to a structure in which the fuel injection valve I is mounted on the air intake system of the engine.

[0040] In a fuel injection valve support structure, in an intermediate portion of a fuel injection valve (I), a first contact surface (5) orthogonal to the central axis (A) of the fuel injection valve (I) and opposed to a fuel supply sleeve (Da) and a pair of second contact surfaces (6, 6) opposed to each other with an intermediate plane (C) containing the central axis (A) and a center line (B) of a clutch (14) are formed.A support member (S) includes: a base plate (15) fitted on the first contact surface (5); an elastic piece (16) extending from the base plate (15) to come into elastic pressure contact with the fuel supply sleeve (Da) and, by its reaction force, to bias the fuel injection valve (I) toward an injection valve mounting hole (10); and a pair of rotation stopper pieces (17, 17) each extending from the base plate (15) to abut against the second contact surfaces (6, 6) and limit rotation of the fuel injection valve (I) about the central axis (A). This makes it easy to limit rotation of the fuel injection valve (I) about its central axis (A).

Claims

[1] A fuel injection valve support structure, wherein: a nozzle portion (2) at a lower end portion of a fuel injection valve (I), which is provided with a power supply coupling (14) projecting from a side surface of the fuel injection valve (I), is inserted into an injector mounting hole (10) of an engine (E); a fuel supply sleeve (Da) of a fuel rail (D) carried by the engine (E) is fitted on a fuel introduction portion (4) at the upper end portion of the fuel injection valve (I); a support member (S) for biasing the fuel injection valve (I) toward the injector mounting hole (10) is interposed between the fuel injection valve (I) and the fuel supply sleeve (Da), wherein a first contact surface (5) and a pair of second contact surfaces (6, 6) are formed in an intermediate portion of the fuel injection valve (I), the first contact surface (5) being orthogonal to the central axis (A) of the fuel injection valve (I) and facing the fuel supply sleeve (Da), the pair of second contact surfaces (6, 6) facing each other with a plane (C) therebetween, the plane (C) containing the central axis (A) and a center line (B) of the coupling (14), and the support member (S) includes a base plate (15), an elastic piece (16), and a pair of rotation stop pieces (17, 17), wherein the base plate (15) sits on the first contact surface (5), the elastic piece (16) extends from the base plate (15) to come into elastic pressure contact with the fuel supply sleeve (Da) and to bias the fuel injection valve (I) toward the injection valve mounting hole (10) by means of the reaction force generated by the pressure contact, wherein each rotation stop piece (17, 17) extends from the base plate (15) to come into contact with the second contact surface (6, 6) and to limit rotation of the fuel injection valve (I) about the central axis (A), characterized bythat each of the rotation stop pieces (17, 17) includes a vertical portion (17a) which extends bent downwards from the corresponding outer side of the base plate (15), and a horizontal portion (17b) which extends laterally from the lower end of the vertical portion (17a), and the second contact surfaces (6, 6) are formed on an outer peripheral surface of a portion (3) in the fuel injection valve (I) whose diameter is the largest, and the distance between the second contact surfaces (6, 6) is approximately equal to the largest diameter of the fuel injection valve (I). [2] The fuel injection valve support structure of claim 1, wherein the pair of rotation stopper pieces (17, 17) are provided with elasticity to cause the pair of rotation stopper pieces (17, 17) to elastically contact the pair of respective second contact surfaces (6, 6). [3] The fuel injection valve support structure according to claim 1 or 2, wherein the base plate (15) includes a U-shaped cutout (19) for receiving the fuel injection valve (I) when the support member (S) is attached to the fuel injection valve (I), a pair of the elastic pieces (16, 16) are provided which are arranged side by side with a gap therebetween, the fuel injection valve (I) being received by the gap, and end portions (17ba) of the horizontal portion (17b) of each of the rotation stopper pieces (17, 17) are bent outward. [4] The fuel injection valve support structure according to any one of claims 1 to 3, wherein a third contact surface (7) parallel to the central axis (A) is formed on an outside surface of the fuel supply sleeve (Da), and a positioning piece (18) for limiting a position of the support member (S) around the central axis (A) by contact with the third contact surface (7) extends from the base plate (15).

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