Series of electromagnetic fuel injection device for internal combustion engines

Abstract

 Each device in the series is formed by connecting together a first (1) and second (24) assembly. The first assembly (1) substantially comprises a body (2) defining a chamber (3) housing an annular electromagnet (4) and a tubular core (5) coaxial with the electromagnet. The second assembly (24) comprises a nozzle (25) in which is formed at least one fuel injection hole (26), a plunger (27) for controlling fuel passage through the injection hole, and a tubular anchor (28) secured to the plunger.

Description

[0001] The present invention relates to a series of electromagnetic fuel injection devices for internal combustion engines, having different fuel injection and supply characteristics.

[0002] Known fuel injection devices substantially comprise a body defining a chamber housing an annular electromagnet and a tubular core coaxial with the electromagnet; a nozzle in which is formed at least one fuel injection hole; a plunger for controlling fuel passage through the injection hole; and a a tubular anchor secured to the plunger.

[0003] Notwithstanding the fact that they substantially comprise the same elements and members as listed above, known fuel injection devices differ as regards numerous design characteristics determining the manner in which the fuel is metered and atomized and supplied to the injector.

[0004] On some devices, the nozzle is cup-shaped and presents a bottom wall, in which the injection hole is formed, and a side wall, while the plunger presents a conical active surface designed to rest on a seat formed in the bottom wall, so as to control fuel passage through the injection hole.

[0005] On others, the nozzle is substantially bell-shaped and presents a top wall, in which the injection hole is formed, and a side wall, while the plunger presents a flat active surface designed to rest on a seat formed in the top wall, again for controlling fuel passage through the injection hole.

[0006] Moreover, for supplying fuel to the injection hole, provision may be made for a substantially axial fuel duct formed inside the core or other parts of the device, or for a substantially radial duct comprising a series of holes formed in the side wall of the body. Currently used devices present widely differing designs, depending substantially on the manner in which the fuel is supplied to the injection hole, the number of injection holes, and the shape and size of the plunger. To meet normal market demand requiring various types of devices for different applications, manufacturers are therefore called upon to produce and store numerous different types, to produce numerous components of different shapes and sizes, and provide for specific assembly lines for each type of device produced.

[0007] The aim of the present invention is to provide a series of electromagnetic fuel injection devices for internal combustion engines, which, despite differences in design in terms of fuel injection and supply, provide for straightforward production involving a limited number of component parts and substantially one production line. A further aim of the present invention is to provide a wide range of devices involving the production and storage of a limited number of component parts and mechanical assemblies.

[0008] Yet a further aim of the present invention is to provide a number of devices of differing performance, which may be inserted inside the same housing on the engine. With these aims in view, according to the present invention, there is provided a series of electromagnetic fuel injection devices for internal combustion engines, said devices presenting different fuel injection and supply characteristics, and each substantially comprising a body defining a chamber housing an annular electromagnet and a tubular core coaxial with said electromagnet; a nozzle in which is formed at least one fuel injection hole; a plunger for controlling fuel passage through said injection hole; and a tubular anchor secured to said plunger; said nozzle presenting a collar for locking said nozzle on to said body, and a spacer washer inserted between said nozzle and the shoulder of a cavity formed in said body and housing said collar and said washer; said cavity in said body communicating with said chamber via a hole coaxial with said cavity and said chamber; characterised by the fact that:
each device in the series is produced by connecting together a first and second assembly;
said first assembly comprising said body, said core and said electromagnet, and said second assembly comprising said nozzle, said plunger, said anchor and said spacer washer;
the diameter of said hole being the same on the bodies of all said first assemblies, the diameter of said cavity being the same on the bodies of all said first assemblies, the diameter of said anchor being the same on all said second assemblies and substantially equal to said diameter of said hole;
the diameter of said collar on said nozzle being the same on all said second assemblies and substantially equal to the diameter of said cavity;
the distance between said shoulder on said body and the end surface of said core being the same on all said first assemblies, and the distance between the top surface of said spacer washer and the top surface of said anchor being the same on all said second assemblies and substantially equal to said distance between said shoulder on said body and said end surface of said core. The present invention will be described by way of example with reference to the accompanying drawings, in which:

Fig.s 1 and 2 show sections of two first assemblies forming part of the devices in the series according to the present invention;

Fig.s 3 to 5 show sections of three second assemblies forming part of the devices in the series according to the present invention;

Fig.s 6 and 7 show devices produced by combining the Fig.1 assembly with those of Fig.s 3 and 4 respectively;

Fig.s 8 and 9 show devices produced by combining the Fig.2 assembly with those of Fig.s 3 and 4 respectively.

[0009] Each device in the series substantially comprises a first assembly 1 designed as shown in Fig.1 or 2.

[0010] Both the assemblies in Fig.s 1 and 2 present substantially the same elements, i.e. a body 2 in which is formed a chamber 3; an annular electromagnet 4 housed inside chamber 3; and a tubular core 5 secured to body 2 in any appropriate manner, e.g. by connecting a flange 6 on core 5 to said body 2. Said first assembly 1 also comprises a cover 7, usually made of plastic and secured to flange 6 of core 5 or to body 2. On the Fig.1 assembly, a rod 9 is forced inside an axial hole 8 formed in core 5, said rod 9 presenting an end shoulder 10 and a sealing ring 11 housed inside an annular groove on the rod itself. On the Fig.2 assembly, a tube 12 is forced inside axial hole 8 in core 5.

[0011] On both the Fig.1 and 2 assemblies, electromagnet 4 is provided with electrical connecting elements 16, and cover 7 is so formed as to insulate the same. Bodies 2 present a side wall 18 and a bottom wall 19. On the Fig.2 assembly, side wall 18 is continuous, whereas that of the Fig.1 assembly presents perforations 20 enabling fuel input to chamber 3.

[0012] On both assemblies, body 2 presents a cavity 21 and a hole 22 enabling communication between cavity 21 and chamber 3.

[0013] The devices in the series also comprise a second assembly 24, three of which are shown in Fig.s 3, 4 and 5. Each said second assembly substantially comprises a nozzle 25 with a fuel injection hole 26; a plunger 27 for controlling fuel passage through hole 26; and an anchor 28 secured to plunger 27. Each second assembly also comprises a spacer washer 29, the bottom surface 30 of which rests on the top surface of nozzle 25, and a helical spring 31.

[0014] Nozzle 25 also presents a collar 32 designed in such a manner as to define, with washer 29, an annular housing 33 for a sealing member 34.

[0015] A second sealing member 37 is fitted about nozzle 25 and located between a pair of annular projections 38 and 39, the former consisting of a washer and the latter of the edge of a bush 40.

[0016] On the Fig.3 assembly, nozzle 25 is cup-shaped with an injection hole 26 formed in the bottom wall; and plunger 27 presents a conical active surface 44 cooperating with a respective surface of injection hole 26, and a pair of annular projections 43 for guiding it inside nozzle 25. On the Fig.4 and 5 assemblies, nozzle 25 is bell-shaped with a top wall in which injection hole 26 may be formed; and plunger 27 presents a flat active surface 44 designed to rest on a flat seat 45 formed in top wall 46 of nozzle 25, in which fuel injection hole 26 is also formed.

[0017] The Fig.5 assembly is the same as in Fig.4, except that it presents a pair of injection holes 48 which may be formed in wall 46 or in a plate secured to nozzle 25. According to the present invention, respective diameters d₁ and d₂ of hole 22 and cavity 21 (Fig.s 1 and 2) are the same on all first assemblies 1. Diameter d_1′ of anchor 28 is the same on all second assemblies 24 and substantially equal to diameter d₁ of hole 22 (Fig.s 1 and 2).

[0018] Diameter d₂′ of collar 32 of nozzle 25 (Fig.s 3 to 5) is the same on all second assemblies 24 and substantially equal to diameter d₂ of cavity 21 (Fig.s 1 and 2).

[0019] Moreover, distance h (Fig.s 1 and 2) between shoulder 51, defined by the bottom surface of cavity 21, and end surface 52 of core 5 is the same on all first assemblies 1; and distance h′ (Fig.s 3, 4 and 5) between top surface 53 of washer 29 and top surface 54 of anchor 28 is the same on all second assemblies 24 and substantially equal to distance h between shoulder 51 and end surface 52 of core 5.

[0020] The axial length h₁ of hole 22 is also conveniently the same on all bodies 2 of first assemblies 1.

[0021] Axial length h₂ of cavity 21 is the same on all bodies 2 of first assemblies 1, and distance h₂′ between top surface 53 of washer 29 and bottom surface 54 of collar 32 of nozzle 25 is the same on all second assemblies 24 and substantially equal to axial length h₂ of cavity 21. The devices in the series may be produced easily by assembling one of second assemblies 24 in Fig.s 3, 4 and 5 on to one of first assemblies l in Fig.s 1 and 2, to produce six different devices. This may be done easily by simply inserting anchor 28 on one of second assemblies 24 inside hole 22 on body 2 of one of assemblies 1, until spacer washer 29 and collar 32 fit inside cavity 21. At this point, second assembly 24 is secured to first assembly 1 by turning end edge 56 of body 2 down over collar 32.

[0022] Any one of second assemblies 24 may be fitted on to any one of first assemblies 1, by virtue of dimensions d₁, d₂, h and h₂ being respectively equal to d₁′, d₂′, h′ and h₂′. Fig.s 6 and 7 show two devices produced by respectively fitting assemblies 24 of Fig.s 3 and 4 on to assembly 1 of Fig.1. Fig.s 8 and 9 show two devices produced by respectively fitting assemblies 24 of Fig.s 3 and 4 on to assembly 1 of Fig.2. The Fig. 6 and 7 devices may be housed inside a cavity 57 into which fuel is supplied, whereas those of Fig.s 8 and 9 may be assembled with nozzle 25 inserted inside a cavity 58 and the top end inside a cavity 59 supplied with fuel.

[0023] The Fig.8 and 9 configurations therefore provide for two devices wherein fuel flows axially and substantially inside tube 12 and the passages formed between the various device components downstream from the same. The plunger on the first device presents a conical active surface 42, whereas that of the second presents a flat active surface 42. On the Fig.6 and 7 devices, on the other hand, fuel is supplied substantially radially, through perforations 20 in body 2 and the passages formed between the device components downstream from the same, and the plunger presents a conical active surface 42 in Fig.6, and a flat active surface 42 in Fig.7. The present invention therefore provides for producing a series of widely differing devices using only two types of assembly, each consisting of a small number of parts of extremely simple design. Manufacture of the devices is therefore limited to producing a small number of components and assemblies, which assemblies may be stored for catering to predetermined market demand. By appropriately combining two different types of assembly, it is therefore possible to produce a device having predetermined characteristics.

[0024] Though only two first and three second assemblies are described and illustrated herein by way of example, any number of assemblies may be provided and combined for forming additional devices.

[0025] To those skilled in the art it will be clear that changes may be made to the design and arrangement of the component parts of the assemblies described and illustrated herein without, however, departing from the scope of the present invention.

Claims

1) - A series of electromagnetic fuel injection devices for internal combustion engines, said devices presenting different fuel injection and supply characteristics, and each substantially comprising a body (2) defining a chamber (3) housing an annular electromagnet (4) and a tubular core (5) coaxial with said electromagnet (4); a nozzle (25) in which is formed at least one fuel injection hole (26); a plunger (27) for controlling fuel passage through said injection hole (26); and a tubular anchor (28) secured to said plunger (27); said nozzle (25) presenting a collar (32) for locking said nozzle (25) on to said body (2), and a spacer washer (29) inserted between said nozzle (25) and the shoulder (51) of a cavity (21) formed in said body (2) and housing said collar (32) and said washer (29); said cavity (21) in said body (2) communicating with said chamber (3) via a hole (22) coaxial with said cavity (21) and said chamber (3); characterised by the fact that:
each device in the series is produced by connecting together a first (1) and second (24) assembly;
said first assembly (1) comprising said body (2), said core (5) and said electromagnet (4), and said second assembly (24) comprising said nozzle (25), said plunger (27), said anchor (28) and said spacer washer (29);
the diameter (d₁) of said hole (22) being the same on the bodies (2) of all said first assemblies (1), the diameter (d₂) of said cavity (21) being the same on the bodies (2) of all said first assemblies (1), the diameter (d₁′) of said anchor (28) being the same on all said second assemblies (24) and substantially equal to said diameter (d₁) of said hole (22);
the diameter (d₂′) of said collar (32) on said nozzle (25) being the same on all said second assemblies (24) and substantially equal to the diameter (d₂) of said cavity (21);
the distance (h) between said shoulder (51) on said body (2) and the end surface (52) of said core (5) being the same on all said first assemblies (1), and the distance (h′) between the top surface (53) of said spacer washer (29) and the top surface (54) of said anchor (28) being the same on all said second assemblies (24) and substantially equal to said distance (h) between said shoulder (51) on said body (2) and said end surface (52) of said core (5).

2) - A series of devices as claimed in Claim 1, characterised by the fact that the axial length (h₁) of said hole (22) in said body (2) is the same on all the bodies of said first assemblies (1) in the series.

3) - A series of devices as claimed in Claim 1 or 2, characterised by the fact that the axial length (h₂) of said cavity (21) is the same on all the bodies of said first assemblies (1) in the series, and the distance (h₂′) between the top surface (53) of said spacer washer (29) and the bottom surface (55) of said collar (32) of said nozzle (25) is the same on all said second assemblies (24) in the series; said axial length (h₂) of said cavity (21) being substantially equal to the distance (h₂′) between said top surface (53) and said bottom surface (55).

4) - A series of devices as claimed in one of the foregoing Claims, characterised by the fact that it comprises first assemblies (1) wherein the lateral wall (18) of said body (2) defining said chamber (3) for said electromagnet (4) is continuous, and by the fact that it comprises first assemblies (1) wherein the lateral wall (18) of said body (2) presents holes (20) for supplying fuel into said chamber (3).

5) - A series of devices as claimed in one of the foregoing Claims, characterised by the fact that it comprises first assemblies (1) wherein said tubular core (5) is closed in fluidtight manner by a rod (9), and by the fact that it comprises first assemblies (1) wherein said core (5) presents an axial hole for supplying fuel into said chamber (3).

6) - A series of devices as claimed in one of the foregoing Claims, characterised by the fact that it comprises second assemblies (24) wherein said nozzle (25) is bell-shaped and presents a top wall (46) and a lateral wall, and wherein said plunger (25) presents a flat active surface (42) designed to rest on a seat (45) formed in said top wall (46) so as to close said fuel injection hole (26) formed in the same; and by the fact that it comprises second assemblies (24) wherein said nozzle (25) is cup-shaped and presents a bottom wall and a lateral wall, and wherein said plunger (25) presents a conical active surface (42) designed to rest on a seat formed in said bottom wall, so as to close said fuel injection hole (26) formed in the same.

7) A series of devices as claimed in one of the foregoing Claims, characterised by the fact that it comprises second assemblies (24) wherein said nozzle (25) presents two or more injection holes formed in a wall or in a plate secured to said nozzle (25).

8) A series of devices as claimed in one of the foregoing Claims, characterised by the fact that the outside diameters of said spacer washer (29) and said collar (32) of said nozzle (25) are the same on all said second assemblies (24) in the series.

Drawing