Blow-by heater

Abstract

A blow-by heater includes a metal pipe for flowing a blow-by gas therethrough. The metal pipe includes a flat portion on one side along an axis direction and a curved portion on a side opposite to the flat portion and is formed of a metal plate with a joining portion abutting against each other at edges of the metal plate at the curved portion. The blow-by gas heater further includes a resin molded over the metal pipe, and a heating source provided inside resin and directly contacting the flat portion.

Claims

1. A blow-by heater, comprising: a metal pipe for flowing a blow-by gas therethrough in a flow direction, the metal pipe including a flat portion on one side along an axis direction of the metal pipe, and a curved portion on a side opposite to the flat portion and including two curved members extending from two edges of the flat portion opposite to each other, each curved member including an inclined portion inclined toward a downstream side in respect to the flat portion so that a cross-sectional area of the metal pipe decreases toward the downstream side, a joining portion in which the two curved members abut against each other, and abutting portions on outer peripheral faces of the two curved members, respectively, and sandwiching the joining portion; a resin covering the metal pipe; and a heating source provided inside the resin and directly contacting the flat portion, wherein the abutting portions are not covered with the resin and are spaced apart from each other in a direction perpendicular to the axis direction.

2. A blow-by heater according to claim 1, wherein the flat portion includes a convex portion or a concave portion for positioning the heating source.

3. A blow-by heater according to claim 1, wherein each of the curved members further includes an arc-shaped end portion at an upstream end of each inclined portion so that an upstream end portion of the curved portion has a semicircular shape, the flat portion has a length greater than that of the curved portion in the axial direction, a downstream end of the metal pipe is defined by downstream ends of the flat portion and the curved portion and an upstream end of the metal pipe is defined by an upstream end of the flat portion being arranged beyond the upstream end portion of the curved portion, and the two edges of the flat portion between the upstream end of the metal pipe and the upstream end portion of the curved portion extend along the axis direction in parallel to each other.

4. A blow-by heater according to claim 3, wherein the two curved members are arranged symmetrical relative to the flat portion so that the joining portion extends along the axis direction between the two curved members.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic perspective view showing a blow-by gas heater of one embodiment of the present invention.

(2) FIG. 2 is a schematic cross-sectional view of the blow-by gas heater in FIG. 1.

(3) FIG. 3 is a schematic front view of the blow-by gas heater in FIG. 1.

(4) FIGS. 4(a) and 4(b) are schematic views for explaining a die when the blow-by gas heater in FIG. 1 is molded.

(5) FIG. 5 is a schematic perspective view showing an upper face of a metal pipe of the blow-by gas heater in FIG. 1.

(6) FIG. 6 is a schematic perspective view showing a conventional blow-by gas heater.

(7) FIG. 7 is a schematic cross-sectional view showing an example wherein the blow-by gas heater in FIG. 6 is provided in a blow-by-gas circulation passage.

BEST MODES OF CARRYING OUT THE INVENTION

(8) Hereinafter, with reference to the attached drawings, an embodiment of the present invention will be explained in detail.

(9) FIG. 1 is a schematic perspective view showing a blow-by gas heater of one embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of the blow-by gas heater in FIG. 1; and FIG. 3 is a schematic front view of the blow-by gas heater in FIG. 1.

(10) As shown in FIG. 1 to FIG. 3, in a blow-by gas heater 10 of one embodiment of the present invention, a metal pipe 5 which becomes a passage of a blow-by gas includes a flat wall portion or smooth wall portion 5d, and a curved wall portion 5e (see FIG. 1). A cross-sectional opening shape of the metal pipe 5 has an approximately half-moon shape. A whole tip of the flat wall portion or smooth wall portion 5d, and a tip of the curved wall portion 5e form a common opening end face 5a of the metal pipe 5 (see FIG. 2). The flat wall portion or smooth wall portion 5d is disposed in such a way as to directly face a heating source 6 which is, for example, a commercially available electronic ceramic heater. In the heating source 6, there is supplied electric power through a plug member 7. Also, the metal pipe 5 includes a throttled portion 5f formed such that a cross-sectional opening area thereof becomes smaller toward a tip side.

(11) The metal pipe 5 as described above is insert-molded into an outer tube 8 made of resin. Specifically, as shown in FIGS. 4(a) and 4(b), a load is applied to abutting portions 5t on an outer peripheral face of the curved wall portion 5e on both sides sandwiching a joining portion of the metal pipe 5 by a die 20 (from a state shown in FIG. 4(a) to a state shown in FIG. 4(b)), and in a state wherein the joining portion of the metal pipe 5 is firmly attached, resin molding is performed around the metal pipe 5 such that even in a case wherein the joining portion of the metal pipe 5 is provided in the curved wall portion 5e, a large gap does not remain. After such insert molding, the die 20 retracts in an axis direction of the metal pipe 5 to be separated from the abutting portions 5t (from the state shown in FIG. 4(b) to the state shown in FIG. 4(a)). Therefore, after the insert molding, the abutting portions 5t become exposed portions without being coated with resin.

(12) As shown in FIG. 1 to FIG. 3, in the present embodiment, the joining portion of the metal pipe 5 corresponds to a ridge line of a top portion of the curved wall portion 5e facing the flat wall portion or smooth wall portion 5d, and there are formed slope portions (which are curved surfaces) extending in a direction perpendicular to the axis direction of the metal pipe 5 on both sides of the ridge line, and there are provided the abutting portions 5t on outer peripheral faces of the slope portions.

(13) Also, as shown in FIG. 5, in order to easily and reliably carry out the positioning of the heating source 6, there are provided convex portions 5p (may be concave portions) for positioning the heating source 6 in the flat wall portion or smooth wall portion 5d.

(14) Next, an operation of the blow-by gas heater 10 of the present embodiment as described above will be explained. The opening end face 5a of the metal pipe 5 is disposed in such a way as to protrude into a gas-intake passage pipe (not shown in the drawings). The blow-by gas is guided inside the metal pipe 5 to flow. In that process, moisture or oil of the blow-by gas, which happens to be condensed, is dissolved by a heat from the heating source 6.

(15) Nevertheless, a small amount of the moisture or oil of the blow-by gas happened to be attached to the metal pipe 5 is guided up to the opening end face 5a so as to become a water droplet or an oil droplet in the opening end face 5a, and scatter into an air flow flowing inside the gas-intake passage pipe (not shown in the drawings). Here, since a size of a scattered water droplet or oil droplet is sufficiently small, even in a case wherein the scattered water droplet or oil droplet freezes and the like thereafter, an ice block thereof has a small volume so as to suppress damages and the like of, for example, a turbo impeller.

(16) According to the blow-by gas heater 10 of the present embodiment as described above, the joining portion of the metal pipe 5 is positioned in the curved wall portion 5e of the metal pipe 5, so that there is no need to interpose, i.e. an intermediate member for protecting the heating source 6 from the blow-by gas, and the heating source 6 can be directly provided in the flat wall portion or smooth wall portion 5d. Thereby, a heat transfer performance notably improves. Also, since there is no need for the intermediate member, an effect of reducing the number of parts can be obtained as well.

(17) Also, according to the blow-by gas heater 10 of the present embodiment, the convex portions 5p for positioning the heating source are provided in the flat wall portion or smooth wall portion 5d so as to easily and reliably carry out the positioning of the heating source 6.

(18) Incidentally, all contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2014-008111 filed on Jan. 20, 2014 are cited in their entireties herein and are incorporated as a disclosure of the specification of the present invention.