Fuel filter of an internal combustion engine

Abstract

Fuel filter of an internal combustion engine, comprising a filter housing (1) with a housing base body (2) made of cast metal and with at least one cover (3, 4), cover screws (5) for fastening the cover (3, 4) to the housing base body (2), and a cover gasket (6, 7) for sealing the cover (3, 4) against the housing base body (2), wherein the housing base body (2) has screw receptacles (8) for the cover screws (5) and a sealing seat (9, 10) for the cover gasket (6, 7), wherein the cover screws (5) are self-tapping screws, and the screw receptacles (8) and the sealing seat (9, 10) are manufactured by casting without machining, characterized in that the cover gasket (6, 7) is a radial gasket, wherein the sealing seat (9, 10) tapers with respect to an axial insertion direction (11, 12) of the cover gasket (6, 7).

Description

Technical area

[0001] The invention relates to a fuel filter of an internal combustion engine having the features according to the preamble of claim 1. State of the art

[0002] Fuel filters for internal combustion engines, particularly in automotive engineering, comprise a filter housing with a housing base and at least one cover. The housing base is often made of cast metal, particularly die-cast aluminum or the like. The cover, which is subject to less mechanical stress, can be made of plastic and is screwed to the housing base using cover screws. A cover seal is arranged between the cover and the housing base to keep the assembled filter housing fuel-tight during operation.

[0003] According to the known state of the art, the metal casting blank of the housing base is machined at least in the area of ​​the screw receptacles for the cover screws and at the sealing seat for the cover gasket. Threads are cut into the screw receptacles. The sealing seat is turned to size, which requires a material allowance of approximately 1 mm for the cast blank. Machining the cast blank requires cost-intensive work steps. The material allowance in the area of ​​the surfaces to be machined increases material costs. The finished fuel filter must meet particularly high requirements with regard to cleanliness as protection against foreign matter in the fuel path. After machining, an intensive flushing process is therefore required to free the machined housing base, which represents a considerable undesirable cost factor.

[0004] US 2 023 423 A relates to strainers, in particular strainers intended for use in the fuel supply lines of oil burners. One of the objects is the provision of an improved strainer unit in which the straining area is significantly increased and which can be disassembled into its elements so that the strainer element can be brushed or cleaned both internally and externally.

[0005] US 7 192 518 B2 relates to a liquid circuit for filtering a liquid, comprising a liquid reservoir, a liquid pump, a consumer, a filter element and a control unit, wherein a heated liquid can be supplied at least partially to the filter element.

[0006] DE 694 05 761 T2 provides a fluid spin-on filter cartridge with a replaceable filter element, comprising a housing, an internally threaded annular collar, a replaceable filter element and an externally threaded mounting head assembly.

[0007] From US 5 985 143 A an outer housing of a water filter with an improved sleeve and a top cover is known, wherein the top cover and the sleeve are formed with inner and outer conical surfaces, wherein the lower half of the conical surface of the outer housing has an external thread.

[0008] DE 102 01 455 A1 relates to a filter container comprising, on the one hand, a filter holder and a lid, each provided with an annular wall which is suitable for interacting by means of a bayonet connection.

[0009] DE 100 23 427 A1 proposes a liquid filter with a pot-shaped housing manufactured using primary forming technology. A threaded bore is provided for attaching the cover to the housing, which can be manufactured without undercuts.

[0010] US 1 584 743 A shows a pot-shaped housing of a fuel filter with a screwed-on cover and a drain plug at the bottom of the housing.

[0011] The invention is based on the object of developing a generic fuel filter in such a way that the requirements for component cleanliness can be met with simple means and with high process reliability.

[0012] This object is achieved by a fuel filter having the features of claim 1. Disclosure of the invention

[0013] A fuel filter is proposed in which the cover screws are self-tapping screws and in which the screw receptacles and the sealing seat are manufactured by casting without any machining.

[0014] Eliminating the need for post-machining reduces manufacturing costs. The absence of additional material at the sealing seat and / or screw receptacles reduces material costs. In particular, no chips are generated during production that pose a contamination risk. Washing the cast metal housing base body is not necessary. With reduced manufacturing costs, the relevant requirements regarding residual manufacturing contamination can be met.

[0015] According to the invention, the cover seal is a radial seal. The sealing seat tapers relative to the axial insertion direction of the cover seal. This takes into account the fact that a cast and not further machined sealing seat has larger manufacturing tolerances than a machined sealing seat. Nevertheless, the conical shape in the insertion direction, in conjunction with the radial seal, results in a reliable sealing effect, as it creates a circumferential, radial contact force between the radial seal and the sealing seat when the seal is inserted axially. At the same time, this also creates a draft angle that facilitates demolding of the cast blank from the mold.

[0016] In an advantageous embodiment, the housing base has a contact surface for the cover, wherein the screw receptacle comprises a one-piece molded spacer sleeve that engages a screw opening in the cover. Preferably, the spacer sleeve extends completely through the screw opening. Without the need for an additional, separate insertion sleeve, the cover is accurately centered by means of the molded spacer sleeve. When the spacer sleeve is fully formed, it acts as an axial stop for the screwed-in cover screw. Overstressing of the cover material is avoided, allowing the cover to be manufactured from a comparatively soft material such as plastic or the like.

[0017] It may be advisable to omit machining in isolated areas, such as the screw receptacles and / or the sealing seat. Preferably, the housing base body is entirely cast without any subsequent machining. Flushing can be omitted if the requirements regarding residual production contamination are met. Short description of the drawings

[0018] An embodiment of the invention is described in more detail below with reference to the drawings. They show: Fig. 1 shows a perspective exploded view of a fuel filter designed according to the invention with a housing base made of die-cast aluminum, with two covers and screw receptacles and sealing seats that are not mechanically reworked; Fig. 2 a longitudinal section of the assembled fuel filter according to Fig. 2 with details of the interaction of the sealing seats with the radial seals of the two covers; Fig. 3 an enlarged schematic detailed representation of a screw connection of the cover to the housing base body according to the invention. Embodiment(s) of the invention

[0019] Fig. Figure 1 shows a perspective exploded view of a fuel filter for an internal combustion engine for a motor vehicle, designed according to the invention. However, other applications of the fuel filter, for example, for stationary engines or the like, can also be envisaged. The fuel filter comprises a filter housing 1, which is formed by a housing base body 2 made of cast metal and two covers 3, 4. Die-cast aluminum is provided for the housing base body 2 here. However, other metal types or casting techniques may also be expedient. The two covers 3, 4 are made of injection-molded plastic.

[0020] The housing base body 2 encloses an interior space in which a filter element 19 is inserted in an axial insertion direction 11. The interior space accommodating the filter element 19 is closed by the cover 3. The cover 3 is provided with a fuel inlet 20 and a fuel outlet 21. The internal combustion engine (not shown) draws in fuel through the fuel outlet 21, through the filter element 19, and the fuel inlet 20, whereby the flowing fuel is cleaned in the filter element 19.

[0021] The further cover 4 is part of a drainage device for draining water and fuel from the interior of the filter housing 1. For this purpose, the cover 4 is provided with a drainage valve 22 and a drainage hose 23.

[0022] Both covers 3, 4 each have a collar with a circumferential radial groove 17, 18 on their side facing the housing base 2. When assembled, a cover seal 6 in the form of an O-ring is inserted into the radial groove 17 of cover 3, while another cover seal 7, also designed as an O-ring, is inserted into the radial groove 18 of cover 4. Different seal designs may also be appropriate.

[0023] In the connection area of ​​the two covers 3, 4, the housing base body 2 is provided with a sealing seat 9, 10 each for receiving the cover seals 6, 7. The sealing seats 9, 10 are circular in cross-section and narrow conically with respect to the respective insertion direction 11, 12. When the covers 3, 4 are assembled, the sealing seats 9, 10 enclose the respective cover seal 6, 7 radially on the outside under radial contact pressure. The covers 3, 4, with their cover seals 6, 7 inserted into the sealing seats 9, 10, are held on the housing base body 2 by cover screws 3, 5, for which purpose the housing base body 2 is provided with one-piece molded-on screw receptacles 8. In addition, the housing base body 2 has further screw receptacles 24 for fastening the filter housing 1 at the installation site.

[0024] The housing base body 2 is manufactured entirely by casting without any subsequent machining. This particularly applies to the sealing seats 9, 10 and the screw receptacles 8, 24. The cast blank of the housing base body 2 is simply removed from the mold after casting, deburred, and rinsed. No further mechanical processing, particularly machining, takes place. Further details on the design of the sealing seats 9, 10 and the screw receptacles 8 are described in connection with the Fig. 2 and Fig. 3 described in more detail.

[0025] Fig. 2 shows a longitudinal section of the assembled filter housing 1 according to Fig. 1. It can be seen that the cover 3 with the molded fuel outlet 21 and the centrally attached filter element 19 is inserted in the insertion direction 11 into the housing base body 2 so far that a circumferential flange 25 of the cover 3 rests flat against a contact surface 13 surrounding the sealing seat 9. The circumferential sealing seat 9, which tapers slightly conically in the insertion direction 11, encloses the cover seal 6 held in the circumferential radial groove 17. The same applies analogously to the cover 4, which is inserted in the insertion direction 12 and rests with its flange 29 against a contact surface 14 of the housing base body 2, the cover seal 7 of which is held in the circumferential radial groove and is enclosed radially on the outside by the sealing seat 10, which tapers slightly conically with respect to the insertion direction 12.The conical design of the sealing seats 9, 10 in conjunction with the axial insertion direction 11, 12 leads to an increasing radial pressure between the sealing seat 9, 10 and the cover seal 6, 7, whereby manufacturing tolerances in the casting-formed sealing seat 9, 10 are compensated.

[0026] Fig. 3 shows, in a schematic detailed representation, an example of a screw connection between the cover 3 and the housing base body 2. The same applies to the screw connection between the cover 4 (not shown here) with the flange 29 and the housing base body 2 with the contact surface 14 ( Fig.2). The cover 3 is provided with a circumferential flange 25, which rests flat against the contact surface 13 of the housing base body 2. The screw receptacle 8, which is molded in one piece onto the housing base body 2, comprises a spacer sleeve 15, which is also molded in one piece and completely extends through a screw opening 16 of the cover 3 in the axial direction. In the area of ​​the screw opening 16, a circumferential collar 26 is optionally provided, which rises above the flange 25 in the axial direction. The free end faces of the collar 26 and the spacer sleeve 15 are flush with one another in the assembled state. The screw receptacle 8 is provided with a blind hole 27, which is open towards the cover screw 5 and has a reduced inner diameter compared to the outer thread diameter of the cover screw 5. In the raw state, the blind hole 27 is smooth on its inner walls, without a thread.The entire screw receptacle 8, including the unthreaded blind hole 27, is cast without any subsequent machining. The cover screw 5 is a self-tapping screw and is screwed into the blind hole 27. The external thread of the cover screw 5 self-tappingly rotates into the undersized blind hole 27. When the cover screw 5 is tightened, its head 28 rests flat against the end faces of the collar 26 and the spacer sleeve 15. This presses the flange 25 of the cover 3 against the contact surface 13. At the same time, the spacer sleeve 15 prevents excessive compression of the cover 3, which is injection-molded from comparatively soft plastic, in the area of ​​the collar 26 or the screw opening 16.

Claims

[1] Fuel filter of an internal combustion engine, comprising a filter housing (1) with a housing base body (2) made of cast metal and with at least one cover 3, 4), cover screws (5) for fastening the cover (3, 4) to the housing base body (2) and a cover seal (6, 7) for sealing the cover (3, 4) relative to the housing base body (2), wherein the housing base body (2) has screw receptacles (8) for the cover screws (5) and a sealing seat (9, 10) for the cover seal (6, 7), wherein the cover screws (5) are self-tapping screws, and the screw receptacles (8) and the sealing seat (9, 10) are manufactured by casting without subsequent machining, characterized by that the cover seal (6, 7) is a radial seal, wherein the sealing seat (9, 10) tapers with respect to an axial insertion direction (11, 12) of the cover seal (6, 7). [2] Fuel filter according to claim 1, characterized bythat the housing base body (2) has a contact surface (13, 14) for the cover (3, 4), and that the screw receptacle (8) comprises a one-piece molded spacer sleeve (15) which engages in a screw opening (16) of the cover (3, 4). [3] Fuel filter according to claim 2, characterized by that the spacer sleeve (15) is completely passed through the screw opening (16). [4] Fuel filter according to one of claims 1 to 3, characterized by that the housing base body (2) is manufactured entirely by casting without any subsequent machining.

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