JP6064944B2 - Electric heating device and exhaust purification system for internal combustion engine - Google Patents

Description

  The present invention relates to an electric heating device and an exhaust purification system for an internal combustion engine.

  An exhaust purification device such as a particulate filter that collects particulate matter in the exhaust gas is disposed in the engine exhaust passage, an electric heating device is disposed in the exhaust passage upstream of the exhaust purification device, and exhaust from the internal combustion engine There is known an exhaust purification system in which gas is heated by an electric heating device and the exhaust purification device is heated by the heated exhaust gas.

  Further, a honeycomb-shaped support is fixed in a casing through which exhaust gas flows, and a honeycomb-shaped electric heating element is disposed upstream of the exhaust gas flow of the support, and the heating element is supported by the support via a support. An electric heating device is known (see Patent Document 1).

JP-A-11-500205

  It is desired to shorten the time required to raise the temperature of the exhaust purification device to the target temperature. This time reduction is achieved by enhancing the heating action of the electric heating device, and in order to enhance this heating action, for example, it is achieved by increasing the number of heating elements.

  However, in the electric heating device of Patent Document 1, it is necessary to increase not only the number of heating elements but also the number of supports that support the heating elements. As a result, a large space is required to arrange the electric heating device. Considering that there is a limit in the space in which the electric heating device can be placed, there is a limit in enhancing the heating action.

  According to one aspect of the present invention, a support is fixed in a casing, a first electric heating element is disposed on one side of the support in the longitudinal axis direction of the casing, and a second is formed on the other side of the support. An electric heating element is arranged, each heating element is provided with an outer cylinder and a belt-like heating element, and each outer cylinder is arranged in the casing such that its central axis is parallel to the longitudinal axis of the casing. Has both end portions fixed to the inner peripheral surface of the corresponding outer cylinder, and intermediate portions extending between the both end portions without being fixed to the corresponding outer cylinder, and each intermediate portion corresponds to A support tool that is wound around a winding axis parallel to the central axis of the outer cylinder and that extends from the first heating element to the second heating element. Fixed to the middle part of the first heating element and the middle part of the second heating element, respectively, The first heating element and the second heating element are supported by the support via the support, and the fluid can pass through the support and the first heating element and the second heating element in the longitudinal axis direction of the casing. An electric heating apparatus is provided in which a fluid flowing in the casing is heated by the first heating element and the second heating element.

  According to another aspect of the present invention, an exhaust purification device is disposed in the engine exhaust passage, the above-described electric heating device is disposed in the exhaust passage upstream of the exhaust purification device, and the exhaust gas from the internal combustion engine is electrically heated. An exhaust gas purification system for an internal combustion engine is provided in which the exhaust gas purification device is heated by the heated exhaust gas and the exhaust gas purification device is heated by the heated exhaust gas.

  The electric heating device can be reduced in size while enhancing the heating action.

It is sectional drawing of an electric heating apparatus. It is a front view of a heat generating body. It is the elements on larger scale of a heat generating body. It is a figure which shows the heating element rewound. It is a figure which shows the layout of a 1st heat generating body and a 2nd heat generating body. It is a figure which shows another Example of the layout of a 1st heat generating body and a 2nd heat generating body. It is sectional drawing of the electric heating apparatus which shows another Example by this invention. It is sectional drawing of the electric heating apparatus which shows another Example by this invention. It is sectional drawing of the electric heating apparatus which shows another Example by this invention. 1 is an overall view of an internal combustion engine.

  Referring to FIG. 1, the electric heating device A includes a cylindrical casing 10, and a columnar support 20 is fixed in the casing 10. In the embodiment shown in FIG. 1, an annular small diameter portion 11 is formed in the casing 10, and the support 20 is fixed to the casing 10 by pressing the small diameter portion 11 against the support 20. The support 20 has a honeycomb structure formed of, for example, ceramic or metal. Therefore, the fluid flowing in the casing 10 can pass through the support 20 in the direction of the longitudinal axis LC of the casing 10.

  A first electric heating element 30a is arranged on one side of the support 20 with respect to the longitudinal axis LC direction of the casing 10 or on the upstream side of the fluid flow, and the other side or fluid of the support 20 with respect to the longitudinal axis LC direction of the casing 10. A second electric heating element 30b is disposed on the downstream side of the flow. These heating elements 30 a and 30 b are supported by the support 20 through the support 40. In this case, the first heating element 30 a and the second heating element 30 b are separated from the casing 10, that is, supported by the support body 20 without being supported by the casing 10. In addition, a slight gap is provided between the first heating element 30 a and the support 20 and between the second heating element 30 b and the support 20.

Next, the first heating element 30a will be described with reference to FIGS. Since the second heating element 30b is similar to the first heating element 30a, the description thereof is omitted.
Referring to FIG. 2, the first heating element 30 a includes a cylindrical outer cylinder 31, and a belt-shaped heating element 32 is accommodated in the outer cylinder 31 in a state of being wound around the winding axis LW. In the embodiment shown in FIG. 2, the winding axis LW coincides with the central axis LHC of the outer cylinder 31. In another embodiment (not shown), the winding axis LW does not coincide with the central axis LHC of the outer cylinder 31, however, it extends in parallel with the central axis LHC of the outer cylinder 31.

  As shown in FIG. 3, the heating element 32 has a honeycomb structure formed by alternately laminating flat plates 33 and corrugated plates 34, and fluid can flow between the flat plates 33 and the corrugated plates 34. A smooth flow path 35 is formed. The outer cylinder 31, the flat plate 33, and the corrugated plate 34 are made of a conductive material, for example, a metal plate.

  FIG. 4 shows a state in which the heat generating element 32 shown in FIG. 2 is rewound and flattened. Referring to FIG. 4, the heat generating element 32 has both end portions 32e and 32e in the length direction LH and an intermediate portion 32i extending between the both end portions 32e and 32e. As shown in FIG. 2, the heat generating element 32 is fixed to and electrically connected to the outer cylinder 31 at both end portions 32e and 32e. In this case, the intermediate portion 32 i is not fixed to the outer cylinder 31.

  2 and 3, the heat generating element 32 is wound so that a gap 36 is formed between a part of the intermediate part 32i and another part of the intermediate part 32i. This gap 36 acts as an electrical insulator.

  The first heating element 30 a further includes an electrode 37 that is electrically connected to the heating element 32. As can be seen from FIGS. 2 and 4, the electrode 37 penetrates the outer cylinder 31 while being electrically insulated from the outer cylinder 31, and is electrically connected to the intermediate portion 32 i of the heat generating element 32. As shown in FIG. 1, the electrode 37 extends through the casing 10 to the outside of the casing 10. The outer cylinder 31 is grounded.

  In the embodiment shown in FIG. 1, the first heating element 30a and the second heating element 30b are arranged so that the central axes LHC of the outer cylinders 31 of the first heating element 30a and the second heating element 30b coincide with each other. Is disposed in the casing 10. In another embodiment (not shown), the central axes LHC of the outer cylinders 31 of the first heating element 30a and the second heating element 30b do not coincide with each other, but extend parallel to each other. Further, in the embodiment shown in FIG. 1, the first heating element is set so that the central axis LHC of the outer cylinder 31 of the first heating element 30 a and the second heating element 30 b coincides with the longitudinal axis LC of the casing 10. 30 a and the second heating element 30 b are arranged in the casing 10. In this case, the flow path 35 of the heat generating element 32 described above extends in parallel to the longitudinal axis LC of the casing 10. In another embodiment (not shown), the central axis LHC of the outer cylinder 31 of the first heating element 30a and the second heating element 30b does not coincide with the longitudinal axis LC of the casing 10, but is parallel to the longitudinal axis LC of the casing 10. Extend to.

  Referring to FIG. 1 again, the support 40 described above extends from the first heating element 30a through the support 20 to the second heating element 30b. In the embodiment shown in FIG. 1, one end of the support 40 is fixed to the first heating element 30 a, the other end of the support 40 is fixed to the second heating element 30 b, and the support 40 is fixed to the support 20. The middle part is fixed. In this case, as shown in FIG. 2, the support 40 is fixed to the intermediate portion 32 i of the heat generating element 32.

  As described above, the heating element 32 of the first heating element 30a and the heating element 32 of the second heating element 30b are accommodated in the outer cylinder 31 in a state of being wound around the corresponding winding axis LW. In this case, due to the elasticity of the heat generating element 32, a force in a rewinding direction acts on the heat generating element 32. The support 40 described above also has an action of maintaining the position of the heat generating element 32 against such a rewinding force. As a result, the gap 36 is reliably maintained and the occurrence of a short circuit is prevented.

  FIG. 5 shows a layout of the first heating element 30a and the second heating element 30b in the electric heating device A shown in FIG. In the embodiment shown in FIG. 5, the winding direction of the heating element 32 of the first heating element 30a and the winding direction of the heating element 32 of the second heating element 30b are opposite to each other. If it does in this way, the direction of the force which rewinds the heat generating element 32 of the 1st heat generating body 30a and the direction of the force which rewinds the heat generating element 32 of the 2nd heat generating body 30b will be mutually opposite. As a result, the force to rewind the heating element 32 of the first heating element 30a and the force to unwind the heating element 32 of the second heating element 30b are canceled out via the support tool 40. Therefore, the position of the heat generating element 32 is reliably maintained.

  Now, when the first heating element 30a and the second heating element 30b are to be operated, the electrode 37 is electrically connected to a power source (not shown). As a result, a current flows through the heat generating element 32 and the heat generating element 32 generates heat, whereby the fluid passing through the heat generating element 32 is heated. In this case, since the fluid is heated by both the first heating element 30a and the second heating element 30b, the fluid can be quickly heated. That is, the heating action of the electric heating device A is enhanced. Moreover, since the two heating elements 30a and 30b are supported by the single support 20, the electric heating device A can be reduced in size. Furthermore, since the heating elements 30a and 30b are fixed to both ends of the support 20, the heating elements 30a and 30b are stably supported.

  By the way, when the heat generating element 32 is formed by winding a laminate of the flat plate 33 and the corrugated plate 34, imperfect regions 38, 38 are formed around both end portions 32e, 32e as shown in FIG. A complete region 39 is formed between the incomplete regions 38 and 38. That is, if the heating element 32 is formed by laminating a predetermined number of flat plates 33 and corrugated plates 34, the number of the flat plates 33 and corrugated plates 34 constituting the complete region 39 is equal to the predetermined number, but incomplete. The number of flat plates 33 and corrugated plates 34 constituting the regions 38, 38 is smaller than the predetermined number. This is because the flat plate 33 and the corrugated plate 34 are shifted from each other in the length direction LH in the imperfect regions 38 and 38. In addition, the electrode 37 described above is electrically connected to one end 39a in the length direction LH on one side surface of the complete region 39. As a result, current flows from the electrode 37 in the complete region 39, and then reaches the outer cylinder 31 via the other side 39b in the length direction LH on the other side of the complete region 39. Here, if the current flows almost uniformly in the complete region 39, almost no current flows in the incomplete regions 38, 38, and therefore the incomplete regions 38, 38 generate little heat. Therefore, the incomplete regions 38 and 38 are referred to as weak heat generation regions. The fluid that has passed through the weak heat generating regions 38, 38 is hardly heated.

  In this regard, in the embodiment shown in FIG. 5, when viewed along the longitudinal axis LC of the casing 10, the weak heat generation region 38 of the first heat generating body 30 a and the weak heat generation region 38 of the second heat generating body 30 b are formed. The first heating element 30a and the second heating element 30b are supported by the support 20 so as not to overlap each other. In other words, the first heating element 30a around the longitudinal axis LC of the casing 10 and the weak heating area 38 of the first heating element 30a and the weak heating area 38 of the second heating element 30b do not substantially overlap each other. The angular position of the second heating element 30b is set. As a result, the fluid that has hardly passed through the weak heating region 38 of the first heating element 30a is prevented from passing through the weak heating region 38 of the second heating element 30b, that is, heat is generated well. Go through the area. Therefore, the temperature variation of the fluid in the radial direction or the circumferential direction of the casing 10 is reduced.

  FIG. 6 shows another embodiment of the layout of the first heating element 30a and the second heating element 30b. In the embodiment shown in FIG. 6, the winding direction of the heating element 32 of the first heating element 30a and the winding direction of the heating element 32 of the second heating element 30b are the same. Further, when viewed along the longitudinal axis LC of the casing 10, the weak heating region 38 of the first heating element 30a and the weak heating region 38 of the second heating element 30b do not substantially overlap each other. The angular positions of the first heating element 30a and the second heating element 30b around the longitudinal axis LC are set. As a result, the temperature variation of the fluid in the radial direction or the circumferential direction of the casing 10 is reduced.

  FIG. 7 shows another embodiment according to the present invention. In the example shown in FIG. 7, the thickness of the support 20 is made smaller than in the embodiment shown in FIG. That is, since the plurality of heating elements 30a and 30b are stably held via the support 40, the support 20 can be made small. Therefore, the electric heating device A is further downsized.

  FIG. 8 shows a further embodiment according to the present invention. In the embodiment shown in FIG. 8, a fixture 41 that fixes at least a part of the support 40 to the inner wall surface of the casing 10 is provided. That is, the support tool 40 adjacent to the casing 10 extends through the first heating element 30a and the second heating element 30b, and the fixing tool 41 extends radially outward at both ends of the support tool 40. Are concatenated. As a result, the support tool 40 is fixed to the inner wall surface of the casing 10 via the fixing tool 41. As a result, the first heating element 30a and the second heating element 30b are supported more stably. In another embodiment (not shown), the fixture 41 is connected to only one of the upstream end and the downstream end of the support 40. In yet another embodiment (not shown), all of the support tool 40 is fixed to the inner wall surface of the casing 10 by the fixing tool 41.

  FIG. 9 shows a further embodiment according to the present invention. In the embodiment shown in FIG. 9, the first support 20a and the second support 20b are arranged in the casing 10 so as to be spaced apart in the longitudinal direction LC, and the first small diameter portion 11a and the second small diameter portion 11b. In FIG. A first heating element 30a is disposed upstream of the first support 20a, a second heating element 30b is disposed between the first support 20a and the second support 20b, and a second A third heating element 30c is disposed downstream of the support 20b. The heating elements 30a, 30b, and 30c are supported by a support member 20a via a support 40 that extends from the first heating element 30a through the first support member 20a and the second support member 20b to the third heating element 30c. , 20b.

  FIG. 10 shows a case where the above-described electric heating device A is applied to an exhaust gas purification system for an internal combustion engine. Referring to FIG. 10, the internal combustion engine main body B is connected to the electric heating device A via the exhaust pipe C1, and the electric heating device A is connected to the exhaust purification device D via the exhaust pipe C2. The exhaust purification device D is formed from a particulate filter that collects particulate matter contained in the exhaust gas, or an exhaust purification catalyst that oxidizes or reduces components in the exhaust gas. When the temperature of the exhaust purification device D is to be raised, the electric heating device A is activated. As a result, the exhaust gas is heated by the electric heating device A, and the exhaust purification device D is heated by the heated exhaust gas. In another embodiment not shown, the casing 10 of the electric heating device A is formed from the exhaust pipe of an internal combustion engine.

A electric heating device 10 casing 20 support 30a first heating element 30b second heating element 31 outer cylinder 32 heating element 32e both end portions 32i intermediate portion 40 support

Claims (5)

  A support is fixed in the casing, a first electric heating element is disposed on one side of the support with respect to the longitudinal axis direction of the casing, and a second electric heating element is disposed on the other side of the support, The heating element includes an outer cylinder and a belt-like heating element, and each outer cylinder is disposed in the casing so that its central axis is parallel to the longitudinal axis of the casing, and each heating element is arranged on the inner circumference of the corresponding outer cylinder. Both end portions fixed to the surface and intermediate portions extending between both end portions without being fixed to the corresponding outer cylinder, each intermediate portion being parallel to the central axis of the corresponding outer cylinder A support member that is wound around the winding axis and that extends from the first heating element to the second heating element through the support member; Each of which is fixed to the middle part of the two heating elements, thereby allowing the first The body and the second heating element are supported by the support, and the fluid can pass through the support and the first heating element and the second heating element in the longitudinal axis direction of the casing. An electric heating device that is heated by a first heating element and a second heating element.   The first heating element and the second heating element are in a state where the winding direction of the intermediate part of the first heating element and the winding direction of the intermediate part of the second heating element are opposite to each other. The electric heating device according to claim 1, wherein the electric heating device is supported by the support.   Each of the first heating element and the second heating element has a weak heating area, and when viewed along the longitudinal axis of the casing, the weak heating area and the first heating element of the first heating element. 3. The electric heating device according to claim 1, wherein the first heating element and the second heating element are supported by the support so that the weak heating area of the two heating elements does not substantially overlap each other. .   Furthermore, the electric heating apparatus as described in any one of Claim 1 to 3 provided with the fixing tool which fixes at least one part of the said support tool to the inner wall face of the said casing.   An exhaust purification device is disposed in the engine exhaust passage, the electric heating device according to any one of claims 1 to 4 is disposed in the exhaust passage upstream of the exhaust purification device, and exhaust gas from an internal combustion engine is supplied to the exhaust passage. An exhaust gas purification system for an internal combustion engine, wherein the exhaust gas purification device is heated by an electric heating device and the exhaust gas purification device is heated by the heated exhaust gas.

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