Device for heating blow-by gases

Abstract

Device for heating blow-by gases of an internal combustion engine, with a tube (1) for guiding the blow-by gases, a heating element (3), a cover (6) which encloses the heating element (3) between itself and the pipe (1), and a sealing zone arranged between the cover (6) and the pipe (1) such that the cover (6) and the pipe (1) are tightly joined above it, wherein the tube (1) is a metal tube surrounded by a plastic sheath (2) which has a recess which is covered by the cover (6), wherein the sealing zone is formed by a seal (7) and is arranged such that an imaginary line, which runs perpendicular to the longitudinal direction of the tube (1) and through the heating element (3), is surrounded by the sealing zone.

Description

[0001] The invention relates to a device for heating blow-by gases.

[0002] From EP 1 460 242 A2 a device for heating blow-by gases of an internal combustion engine, comprising a tube for guiding the blow-by gases, a heating element, and a cover which encloses the heating element between itself and the tube in a gas-tight manner.

[0003] A device for heating blow-by gases is also known from DE 103 25 965 B4. This heating device has a PTC heating element that sits in a recess in a plastic sheath on a metal tube. An electrical contact element of a connector rests springily on the PTC heating element, while a second contact element of the connector presses against the metal tube in a second recess in the plastic sheath. The two recesses are closed by a cover that forms the connector housing. The contact pins of the connector are electrically connected to each of the two contact elements. During assembly, the connector housing is welded to the plastic sheath, thus sealing the connector area from the outside.

[0004] Another device for heating blow-by gases is also known from DE 102 37 762 A1. This device has a tube for guiding the blow-by gases, a heating wire winding surrounding the tube, and a plastic casing that seals around the tube and the heating wire winding.

[0005] From JP H10-231 543 A a heating device is known in which a cylindrical heating element protrudes through a bore into a pipe.

[0006] WO 99 / 47805 A1 also shows a device for heating blow-by gases. Here, the heating device is also designed as a heating ring surrounding the pipe at the inlet point to the intake line, in various configurations.

[0007] Blow-by gases are gases that escape from the combustion chamber between the cylinder wall and piston during fuel combustion. These blow-by gases contain fuel and aggressive contaminants and must therefore not be released into the environment. Typically, blow-by gases are recirculated from the crankcase back into the intake manifold via a blow-by line. At low temperatures, moisture contained in the blow-by gases can freeze and, in extreme cases, clog the line. To prevent this, a device for heating the blow-by gases is installed in the line.

[0008] The object of the present invention is to demonstrate a way in which a device for heating blow-by gases can be created that enables a more reliable seal of the heating element as well as a good thermal connection of the heating element to the pipe.

[0009] This problem is solved by an electric heating device with the features specified in claim 1. Advantageous embodiments of the invention are the subject of dependent claims.

[0010] In a device according to the invention, the cover is tightly joined to the tube around the heating element by means of a sealing zone, namely a gasket, preferably an elastomeric gasket, arranged between the tube and the cover. According to the invention, the sealing zone, i.e., the gasket, is arranged such that every geometric straight line passing through the heating element perpendicular to the longitudinal direction of the tube, i.e., in the radial direction of the tube, is surrounded by the sealing zone, i.e., the gasket. The tube is therefore not completely surrounded by the sealing zone or the gasket and does not cover its entire circumference, but only a portion thereof, and also extends in the longitudinal direction of the tube. Preferably, the gasket surrounds the heating element or a base supporting the heating element.

[0011] In this way, the volume containing the heating element, namely the space surrounded by the cover and the metal tube, is sealed more reliably and protected from the fluid to be heated than would be possible with the welding of the plug housing to a plastic sheath of the metal tube known from DE 103 25 965 B4. With the known device, gases can seep between the tube and the sheath and damage the heating element.

[0012] Preferably, the seal is a sealing ring that seals a joint between the cover and the pipe. It is further preferred that the cover is a connector housing.

[0013] A major advantage of this design is that the cover, along with the heating element (preferably a PTC heating element) and the sealing ring, can be pre-assembled as a single unit. This unit then simply needs to be attached to the pipe (preferably made of metal) and secured, for example, by snapping, embossing, gluing, welding, or crimping. Preferably, the cover has a groove in which the sealing ring is held. Alternatively or additionally, the sealing ring can be glued or injection-molded onto the cover. The sealing ring can also be attached to the pipe; for example, the pipe can have a groove or a shoulder for this purpose. Alternatively, the sealing ring can be glued or injection-molded onto the pipe.

[0014] The heating element can be attached to a connector housing formed by the cover by means of a contact pin of the connector that protrudes through a base of the connector housing and is, for example, designed as a bent section of a contact plate. The heating element can be soldered to this contact plate. Preferably, however, the heating element is held between two contact plates, each of which has a bent section that protrudes through the base of the connector housing as a contact pin. In the case of overhead mounting, the components can also be positioned loosely within the connector housing.

[0015] The sealing ring of a device according to the invention can, for example, be an O-ring, a molded seal, or a bead of elastomeric material. The sealing ring can, for example, rest on a flattened support surface of the tube that carries the heating element. It is also possible for the sealing ring to surround a base formed by the tube that carries the heating element. Such a base can advantageously form a flattened support surface on which the heating element rests.

[0016] According to the invention, the tube is made of metal and surrounded by a plastic sheath, which has a recess covered by the cover and in which the sealing ring is arranged. The sealing ring ensures a reliable seal of the volume covered by the cover, even without complex welding of the cover to the plastic sheath, thus protecting the heating element arranged therein together with two contact elements, for example contact plates, from moisture and dirt. If, in a device according to the invention, the cover and plastic sheath are not welded together, they can advantageously be made of different plastics.

[0017] An advantageous further development provides that the plastic sleeve forms fastening elements that engage with the cover. This facilitates the correct positioning of the cover. The fastening elements can, for example, be designed as pins. The fastening elements can create a force-fit connection between the cover and the plastic sleeve, for example by crimping. Preferably, the cover and plastic sleeve are positively connected by the fastening elements, for example by snapping or by embossing the fastening elements, in particular by hot embossing, after they have been inserted through openings in the cover, for example holes in a flange.

[0018] A further advantageous embodiment of the invention provides that the tube forms a base which supports the heating element. The seal can surround the base or rest on it. Preferably, the base forms a flattened support surface for the heating element. A flattened support surface facilitates good thermal coupling of the heating element to the tube, but can also be achieved, for example, without a base by simply flattening a portion of the tube's outer surface.

[0019] Another aspect of the invention relates to a device for heating blow-by gases of an internal combustion engine, comprising a tube for guiding the blow-by gases, a heating element, and a cover which encloses the heating element between itself and the tube, wherein the cover and the tube are tightly joined via a sealing zone which is arranged such that an imaginary line, perpendicular to the longitudinal direction of the tube and passing through the heating element, is surrounded by the sealing zone.

[0020] The sealing zone can be formed or sealed by a gasket as described above. In this context, it should be noted that a plastic sheath surrounding the pipe is considered part of the heating device, but not part of the pipe itself.

[0021] Further details and advantages of the invention are explained using exemplary embodiments with reference to the accompanying drawing. Identical and corresponding components are designated by corresponding reference numerals. The drawing shows: Fig. 1. A partially cutaway view of a device for heating blow-by gases, Fig. 2 the in Fig. 1 Device shown without connector housing; Fig. 3 a detailed view of another embodiment of a device for heating blow-by gases, Fig. 4 Another embodiment of a device for heating blow-by gases in a sectional view.

[0022] The in the Fig. 1 and Fig. The device shown in Figure 2 is used to heat blow-by gases and is intended to be installed in a blow-by line. The heating device shown has a metal tube 1 surrounded by a plastic jacket 2. The plastic jacket 2 is preferably injection-molded around the metal tube 1, which can be made of aluminum, for example, and can be longer than the metal tube 1, thus extending the metal tube 1.

[0023] The plastic casing 2 has a recess, which is particularly useful in Fig. Figure 2 shows that in this recess, the metal tube 1 forms a, preferably flat, support surface that carries a ceramic PTC heating element 3. A contact plate 4 can be arranged between the metal tube 1 and the PTC heating element 3. However, it is also possible that the metal tube 1 itself is used for electrical contact with the PTC heating element 3. A contact plate 5 rests on the PTC heating element 3. In the illustrated embodiment, the PTC heating element 3 is thus arranged between two contact plates 4 and 5.

[0024] Preferably, an intermediate layer, not shown in the figures, is placed between the contact plate 4 and the metal tube 1. This intermediate layer improves heat transfer to the metal tube 1 by smoothing out minor irregularities and thus increasing the heat-conducting surface area. The intermediate layer is preferably a film, but can also be applied to the metal tube as a lacquer or other coating. Alternatively or additionally, the intermediate layer can also provide electrical insulation. This ensures that the metal tube is potential-free, which is particularly advantageous when heated with higher electrical voltages. The intermediate layer can be made of a film, for example, from plastic or a ceramic material.

[0025] The contact plates 4, 5 each have a bent section 4a, 5a that forms a contact pin of a connector. The contact pins protrude through the base of a connector housing 6, which covers the recess of the plastic sheath 2. The PTC heating element 3 is thus enclosed in an interior space between the metal tube 1 and the connector housing 6. This interior space is sealed by a sealing ring 7, which rests on the metal tube 1 and surrounds the PTC heating element 3. The sealing ring 7 preferably sits in a groove of the connector housing 6 and is pressed between the connector housing 6 and the metal tube 1, in particular between the connector housing 6 and the support surface of the metal tube 1.

[0026] In the illustrated embodiment, the plastic sheath 2 has fastening elements 2a that engage in the connector housing 6, for example, in holes of a flange formed by the connector housing 6. Alternatively, the connector housing may also have fastening elements that engage in the plastic sheath. The fastening elements 2a, which may be designed as pins, for example, facilitate positioning the connector housing 6 on the recess of the plastic sheath 2. After the connector housing 6 is placed on the sheath, the fastening elements 2a can be hot-stamped, thus creating a positive-locking or even material-locking connection between the connector housing 6 and the plastic sheath 2. Welding, bonding, or snapping of the plastic sheath 2 and the connector housing 6 is also possible.

[0027] The contact plate 5 between the base of the connector housing 6 and the PTC heating element 3 can form a spring tab 5b that presses against the connector housing 6. Such spring tabs 5b can be cut from a base surface of the contact plate 5b and then positioned. One or more spring tabs 5b improve the thermal coupling of the PTC heating element 3 to the metal tube 1 and compensate for tolerances. Specifically, the spring tabs 5b press the PTC heating element 3 downwards against the metal tube 1 or against the contact plate 4 located between the metal tube 1 and the PTC heating element. As an alternative to such spring tabs, separate spring elements can also be used, which are positioned between the contact plate and the connector housing.

[0028] The illustrated device for heating blow-by gases can be manufactured by first pre-assembling the plug housing 6 with the sealing ring 7, the PTC heating element 3 and the contact plates 4, 5 into a plug assembly, which is then placed onto the recess in the plastic sheath 2 of the metal tube 1.

[0029] To pre-assemble the connector assembly, the sealing ring 7 is inserted into the groove of the connector housing 6. When the connector assembly is placed onto the recess of the plastic sheath 2, the sealing ring 7 then contacts the metal tube 1 and is pressed into place.

[0030] Furthermore, for pre-assembly of the connector assembly, bent sections 4a, 5a of the two contact plates 4, 5, between which the PTC heating element 3 is arranged, are inserted through openings in the base of the connector housing 6. The PTC heating element 3 is then held between the two contact plates 4, 5, which in turn are attached to the connector housing 6.

[0031] The heating device is assembled by placing the connector housing 6, or more precisely the connector assembly, onto the recess in the plastic sheath 2. The fastening elements 2a of the plastic sheath 2 engage in designated openings in the connector housing 6. These openings are preferably provided in a flange of the connector housing 6. The fastening elements 2a can create a snap-fit ​​connection. Particularly if the fastening elements are simpler in design, for example as pins, they can be connected to the connector housing 6 by crimping or riveting.

[0032] Fig. Figure 3 shows a detailed view of another embodiment of a device for heating blow-by gases. In this embodiment, the sealing ring 7 is not seated in a groove of the connector housing 6, but instead in a groove formed between the plastic sheath 2 and a base formed by the metal tube 1. As in the embodiment of Fig. 1 and Fig. 2 carries a flattened support surface of the metal tube 1 and the PTC heating element 3. This flattened support surface is formed by a base 1a, which is surrounded by the sealing ring 7. The sealing ring 7 therefore rests against the plastic sheath 2, the metal tube 1, and the connector housing 6, and is compressed between these three components. Advantageously, this allows a seal to be achieved not only between the metal tube 1 and the connector housing 6, but also between the metal tube 1 and the plastic sheath 2, thus also providing an external seal. Alternatively, two sealing rings can be used.

[0033] In Fig. Figure 4 shows a further embodiment of a device for heating blow-by gases in a sectional view. In this embodiment as well, the metal tube 1 forms a base 1a, which is surrounded by the sealing ring 7.

[0034] The sealing ring 7 is held in a groove of the connector housing 6. A plastic sleeve 2 is provided for the metal tube 1, and the connector housing 6 is attached to this plastic sleeve 2.

[0035] In this embodiment as well, the base 1a of the metal tube 1 forms a flattened support surface for the PTC heating element, which is located in Fig. Figure 4 is not shown for the sake of simplicity. The support surface can be designed as the inner surface of a pipe channel 8. A package consisting of the PTC heating element, one or two contact plates, and one or two insulating layers can be inserted into such a pipe channel 8. The package is then compressed by applying pressure to the upper cover wall of the pipe channel. This eliminates the need for a spring element. Reference figures 1 pipe 1a Base 2 plastic sheath 2a Fasteners 3 PTC heating elements 4 contact plates Section 4a 5 contact plate Section 5a 5b Spring tab 6 Cover 7 Sealing ring 8 Pipe channel

Claims

[1] Device for heating blowby gases of an internal combustion engine, with a pipe (1) for conducting the blowby gases, a heating element (3), a cover (6) which encloses the heating element (3) between itself and the tube (1), and a sealing zone arranged between the cover (6) and the pipe (1) such that the cover (6) and the pipe (1) are tightly joined thereover, wherein the tube (1) is a metal tube surrounded by a plastic sheath (2) having a recess covered by the cover (6), wherein the sealing zone is formed by a seal (7) and arranged such that an imaginary line running perpendicular to the longitudinal direction of the pipe (1) and through the heating element (3) is surrounded by the sealing zone. [2] Device according to claim 1, characterized by that the seal (7) surrounds the heating element (3) or a base (1a) supporting the heating element (3). [3] Device according to claim 1 or 2, characterized by that the seal (7) is a sealing ring. [4] Device according to claim 3, characterized by that the cover (6) has a groove in which the sealing ring (7) sits. [5] Device according to one of the preceding claims, characterized by that the cover (6) is a connector housing. [6] Device according to claim 5, characterized by that between a base of the plug housing (6) and the heating element (3) there is a contact plate (5) which has a bent section (5a) which forms a contact pin of a plug. [7] Device according to claim 6, characterized by that the contact plate (5) forms a spring tab (5b) which presses against the plug housing (6). [8] Device according to one of claims 5 to 7, characterized bythat between the heating element (3) and the tube (1) there is a contact plate (4) which has a bent section (4a) which forms a contact pin. [9] Device according to claim 8, characterized by that an intermediate layer, preferably a film, is arranged between the contact plate (4) and the tube (1). [10] Device according to one of the preceding claims, characterized by that the heating element (3) is a ceramic PTC heating element. [11] Device according to one of the preceding claims, characterized by that the plastic casing (2) forms fastening elements (2a) which engage in the cover (6). [12] Device according to one of the preceding claims, characterized by that the plastic casing (2) is positively connected to the cover (6), preferably locked.

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