JP2009117127A - Tube heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipe heating device capable of heating a pipe to be heated excellently with a structure with little constraint. <P>SOLUTION: The pipe heating device 10 is provided with a tube 14 which is installed along a longitudinal direction of the pipe to be heated 12 and covers the pipe to be heated 12 so as to form a heating air passage 20 between the pipe to be heated 12, a jet pump 18 which generates an air stream in the heating air passage 20 along the longitudinal direction of the pipe to be heated 12, and a heater 16 which heats the air flowing in the heating air passage 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tube heating apparatus for heating a tube.

As a countermeasure against freezing of a urea water supply pipe that guides urea water as a reducing agent, a technique is known in which an electric heater is arranged along the outer periphery of the pipe body, and the electric heater is covered with a plain weave mesh. (For example, refer to Patent Document 1).
JP 2005-325691 A JP 2006-125480 A

  However, in the conventional technology as described above, it is necessary to provide an electric heater over the entire length of the pipe, and there are many restrictions on adding a heating structure.

  In view of the above facts, an object of the present invention is to obtain a tube heating apparatus that can heat a tube to be heated satisfactorily with a configuration with few restrictions.

  A tube heating apparatus according to the invention of claim 1 is provided along the longitudinal direction of the tube to be heated, and a covering that covers the tube to be heated so that a gap is formed between the tube and the tube to be heated. An air flow generating means for generating an air flow along a longitudinal direction of the heated tube in a gap between the heated tube and the covering, and a gap between the heated tube and the covering. Heating means for heating the flowing air.

  In the tube heating apparatus according to the first aspect, when the heating unit and the air flow generation unit are operated, the air heated by the heating unit flows through the gap between the covering and the heated tube. As a result, the heated tube is heated by heat exchange with the heating air. For this reason, it is sufficient to provide the heating means partially (one or more) in the longitudinal direction of the tube to be heated. That is, in the main tube heating apparatus, the heated tube can be satisfactorily heated without providing a means for heating the heated tube over the entire length. For this reason, in the main pipe heating device, for example, it is possible to cope with different lengths of the heated pipe only by changing the length of the covering, or to eliminate the trouble countermeasures required for the long heating means. Yes, there are few restrictions.

  Thus, in the tube heating apparatus according to the first aspect, the heated tube can be satisfactorily heated with a configuration with few restrictions.

  A tube heating device according to a second aspect of the present invention is the tube heating device according to the first aspect, wherein the heating means is provided at least at a longitudinal end portion of the covering.

  In the tube heating apparatus according to claim 2, since the heating means is arranged at the longitudinal end of the covering, the air flow generating means generates an air flow in one direction, so that the pre-installation range of the covering is set. Heating air can be circulated.

  According to a third aspect of the present invention, there is provided the tube heating apparatus according to the first or second aspect, wherein the air flow generating means includes a jet pump provided at a longitudinal end portion of the covering body. It consists of

  In the tube heating device according to claim 3, since the air flow generating means includes a jet pump, in an application capable of supplying the driving fluid, air is not provided in the gap between the covering and the heated tube without using any separate power. A flow can be generated. Further, the heating means and the air flow generating means can be arranged apart from each other in the longitudinal direction of the heated tube.

  The tube heating device according to a fourth aspect of the present invention is the tube heating device according to any one of the first to third aspects, wherein the covering is a gap over the entire circumference between the tube to be heated. Is provided.

  In the tube heating apparatus according to the fourth aspect, the heated tube is efficiently heated by performing heat exchange with the heating air over the entire circumference.

  As described above, the tube heating device according to the present invention has an excellent effect that the heated tube can be heated satisfactorily with a configuration with few restrictions.

  A tube heating apparatus 10 according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 shows a schematic overall configuration of the tube heating device 10 in a cross-sectional view. As shown in this figure, the tube heating apparatus 10 includes a tube 14 as a covering that covers the heated tube 12. The tube 14 has an inner diameter larger than the outer diameter of the heated tube 12, and covers the heated tube 12 from the outer peripheral side by inserting the heated tube 12 into the tube 14. The heated tube 12 is arranged coaxially with the heated tube 12 via a heater 16 and a jet pump 18 (and a support body (not shown) that supports them with respect to the heated tube 12) described later.

  Therefore, in the tube heating device 10, a gap over the entire circumference is formed between the outer peripheral surface 12 </ b> A of the tube 12 to be heated and the inner peripheral surface 14 </ b> A of the tube 14, and this gap is used as the heating air flow path 20. ing. In the heating air flow path 20, both ends in the longitudinal direction of the tube 14 are open ends 20 </ b> A and 20 </ b> B.

  Further, the tube heating device 10 generates an air flow in the heating air flow path 20 along the longitudinal direction of the tube to be heated 12, specifically, an air flow for generating an air flow from the opening end 20A toward the opening end 20B. A jet pump 18 is provided as generation means. The jet pump 18 discharges air from the driving fluid inlet portion 22 through which the driving fluid flows in, the air suction portion 24 to which the opening end 20B of the heating air passage 20 is connected, and the driving fluid and the heating air passage 20. The discharge unit 26 is configured as a main part.

  In the jet pump 18, the driving fluid inlet portion 22, the air suction portion 24, and the discharge portion 26 each have a coaxial cylindrical shape, and are arranged so that the heated pipe 12 is inserted through the axial center portion thereof. Yes. In this posture, an air outlet gap 28 communicating with the heating air flow path 20 is formed over the entire circumference between the outer peripheral surface 12A of the heated pipe 12 and the inner surface (minimum diameter portion) of the jet pump 18. . In this posture, the jet pump 18 is supported via a support body (not shown) so that the relative position with respect to the heated tube 12 does not change.

  The jet pump 18 sucks out the air in the heating air flow path 20 through the air sucking portion 24 by applying a flow of the driving fluid flowing in from the driving fluid inlet portion 22 and flowing out from the discharge portion 26. Has been. Therefore, in the tube heating apparatus 10, the air flow Fh (from the opening end 20 </ b> A toward the opening end 20 </ b> B in the heating air flow path 20 is provided in the heating air flow path 20 by applying the flow Fd (see FIG. 1) of the driving fluid to the jet pump 18. 1) is generated.

  Furthermore, the tube heating device 10 includes a heater 16 as a heating means. In this embodiment, the heater 16 is an electric heater (for example, a PTC heater or an NTC heater) that generates heat when supplied with power (supplied) from a power source 32. The heater 16 is formed in a substantially cylindrical shape, and is arranged so that the heated tube 12 is inserted through the axial center portion thereof. In this posture, an air inlet gap 30 communicating with the heating air flow path 20 is formed over the entire circumference between the outer peripheral surface 12A of the heated tube 12 and the inner surface (minimum diameter portion) of the heater 16.

  In this posture, the heater 16 is supported via a support (not shown) so that the relative position with respect to the heated tube 12 does not change. In addition, an opening end 20 </ b> A is connected to the heater 16 in the heating air flow path 20. Therefore, the heater 16 is configured to heat the air flow Fh flowing through the heating air flow path 20 at the inflow portion into the heating air flow path 20 when energized.

  In this embodiment, the heated tube 12 and the tube 14 are both made of a flexible resin (having flexibility) structure. For this reason, when the heated tube 12 has a bent portion, the axial centers of the heated tube 12 and the tube 14 are shifted at the bent portion, or the outer peripheral surface 12A of the heated tube 12 and the inner peripheral surface 14A of the tube 14. May contact in a part of the circumferential direction, but the effect on the heating efficiency by these is small. Further, in order to make the gap between the heated tube 12 and the tube 14 substantially constant even at the bent portion or the like, a spacer that allows the air flow Fh may be provided between the heated tube 12 and the tube 14.

  Next, the operation of this embodiment will be described.

  In the pipe heating device 10 having the above-described configuration, when the flow Fd of the driving fluid is applied to the jet pump 18, the air inlet gap 30 () is provided in the heating air flow path 20 formed between the heated pipe 12 and the tube 14. An air flow Fh is generated from the opening end 20A) toward the air outlet gap 28 (opening end 20B). At this time, if the heater 16 is energized, the air passing through the air inlet gap 30 is heated by the heat generated by the heater. That is, the air flow Fh becomes a flow of heating air heated by the heater 16.

  Thereby, in the tube heating device 10, the heated tube 12 is heated by heat exchange with the heating air.

  Here, in the tube heating apparatus 10, the heated tube 12 is heated by generating the air flow Fh of the heated air in the heated air flow path 20, and thus the heated tube 12 is directly connected over the entire length. The heated tube 12 can be heated without using an electrically heated heater or the like. That is, by providing the heater 16 partially in the longitudinal direction of the heated tube 12, it is possible to realize a configuration in which the heated tube 12 is overheated over the entire length (required length). In this embodiment, the structure which can heat the to-be-heated tube 12 over required length (length of the tube 14) with one heater 16 was implement | achieved.

  For this reason, in the tube heating apparatus 10, only the tube 14 (the length thereof) is changed (the number of the heaters 16 may be changed as necessary), so that the tube to be heated 12 having a different length can be easily handled. can do. For example, when the electric heater is provided over the entire length of the heated tube 12, there is a concern about disconnection in the middle (particularly in the case of the flexible heated tube 12) due to the long wire length of the heater, and the length of the heated tube 12. A special length of electric wire (electric heater) is required for each length, and connection with the longitudinal ends of the tube to be heated 12 or return wiring of the electric wire is required. Occurs.

  On the other hand, in the tube heating apparatus 10, the structure which heats the to-be-heated tube 12 of different length by the change of the length (installation position of the heater 16 and the jet pump 18) of the tube 14 is easily realizable. Further, in the tube heating device 10, there is little risk of disconnection (failure) of the heater 16, and it is possible to eliminate special measures for failure.

  Further, in the tube heating device 10, since the heater 16 is provided at the longitudinal end of the tube 14, the air flow Fh directed in one direction from the heater 16 (air inlet gap 30) is generated. The heating tube 12 can be heated satisfactorily.

  Further, in the tube heating apparatus 10, the air flow Fh is generated by the jet pump 18, and therefore, when applied to an application in which the flow Fd of the driving fluid that can be supplied to the jet pump 18 is obtained, the air is used without using power separately. A flow Fh can be generated. Further, the jet pump 18 that generates the air flow Fh by sucking air from the heating air flow path 20 can be provided on the side opposite to the heater 16 side in the tube 14 (heating air flow path 20). For this reason, for example, in the configuration in which the heated pipe 12 is heated over the entire length, the heating means and the air flow generating means can be arranged within the range of the length of the heated pipe 12. The heater 16 and the jet pump 18 can also be used as a support member that supports the longitudinal direction of the tube 14.

  Furthermore, in the tube heating apparatus 10, since the heating air flow path 20 is formed over the entire circumference of the tube 12 to be heated, the tube 12 to be heated is efficiently heated over the entire periphery.

  Next, an application example in which the tube heating device 10 is applied to a urea SCR (Selective Catalytic Reduction) system 40 as an exhaust gas purification device for purifying exhaust gas of an internal combustion engine that is a drive source of a vehicle is based on FIG. I will explain.

  As shown in FIG. 2, the urea SCR system 40 includes a selective reduction NOx catalyst 46 as an exhaust gas purification catalyst provided downstream of an oxidation catalyst (not shown) in an exhaust pipe 44 of a diesel engine 42, and urea water as a reducing agent. Are provided in the urea water tank 48, the urea water supply pipe 50 that leads the urea water in the urea water tank 48 between the oxidation catalyst and the selective reduction NOx catalyst 46 in the exhaust pipe 44, and the urea water supply pipe 50. The urea water pump 52 and the urea water injection valve 54 provided at the connecting portion between the urea water supply pipe 50 and the exhaust pipe 44 are mainly configured.

  The urea SCR system 40 supplies urea water to the exhaust pipe 44 by operation of the urea water pump 52. The reducing gas (ammonia gas) obtained by reducing the supplied urea flows into the selective reduction NOx catalyst 46 together with the exhaust gas, and the selective reduction NOx catalyst 46 selectively reduces or decomposes NOx in the exhaust gas. It has become. Thereby, the urea SCR system 40 is configured to purify the exhaust gas of the diesel engine 42.

  In the urea SCR system 40, the tube heating device 10 is provided to prevent the urea water supply pipe 50 from freezing or to melt the urea water in the urea water supply pipe 50. That is, the tube heating apparatus 10 in this application example is configured to heat the outer portion of the urea water tank 48 in the urea water supply pipe 50 as the heated tube 12 over substantially the entire length.

  In this application example, as the flow Fd of the driving fluid supplied from the jet pump 18, the traveling wind of the vehicle on which the urea SCR system 40 is mounted or the air flow from the cooling fan of the radiator is used. Thereby, in the pipe | tube heating apparatus 10 in this application example, the jet pump 18 can be functioned and the air flow Fh can be produced | generated, without using independent (exclusive) motive power.

  In a vehicle equipped with the urea SCR system 40, an air flow Fh is generated in the heating air flow path 20 as the vehicle travels. When freezing of urea water is predicted, such as when the outside air temperature drops while the vehicle is running, an ECU as a control device (not shown) energizes the heater 16. Then, an air flow Fh of the heating air heated by the heater 16 is generated in the heating air flow path 20, the urea water supply pipe 50 is heated, and the urea water in the urea water supply pipe 50 is frozen. Is prevented.

  When the urea water freezes while the vehicle is parked or the like, the ECU energizes the heater 16 at the start of traveling. Then, an air flow Fh of the heating air heated by the heater 16 is generated in the heating air flow path 20, the urea water supply pipe 50 is heated, and the frozen urea water is melted. When urea water is melted and urea water is supplied to the exhaust pipe 44, the NOx concentration in the exhaust gas decreases. The ECU stops energization of the heater 16 when it is determined that the NOx concentration has reached the set position based on the output of the NOx sensor.

  In the urea SCR system 40, by applying the tube heating device 10, the urea water can be prevented from freezing and the frozen urea water can be melted without providing an electric heater over the entire length of the urea water supply pipe 50. Since the urea water supply pipe 50 vibrates as the vehicle travels, in the configuration in which the electric heater is provided over the entire length, there is a concern about disconnection of the electric heater, but in the pipe heating apparatus 10, the urea water supply pipe 50 Since it suffices to arrange the heater 16 on a part of the urea water tank 48 (urea water pump 52) side, there is little risk of disconnection and high reliability.

  In addition, the use of the tube heating device 10 according to the embodiment of the present invention is not limited to the use applied to the urea SCR system 40 which is the above-described application example, and the tube heating is used for various uses for heating the tube. The device 10 can be applied.

  In the above-described embodiment, an example in which the jet pump 18 is used as the air flow generation unit has been described. However, the present invention is not limited to this, and for example, an air flow that generates the air flow Fh by power of an electric fan or the like You may use a production | generation means.

It is sectional drawing which shows the schematic whole structure of the tube heating apparatus which concerns on embodiment of this invention. It is a system configuration figure showing an example in which a tube heating device concerning an embodiment of the present invention was applied to a urea SCR system.

Explanation of symbols

10 Tube Heating Device 12 Heated Tube 14 Tube (Coating)
16 Heater (heating means)
18 Jet pump (air flow generation means)
20 Heating air flow path (gap)
Fh air flow

Claims (4)

A covering that is provided along the longitudinal direction of the tube to be heated and covers the tube to be heated so that a gap is formed between the tube and the tube to be heated;
An air flow generating means for generating an air flow along a longitudinal direction of the heated tube in a gap between the heated tube and the covering;
Heating means for heating the air flowing through the gap between the heated tube and the covering;
A tube heating device.   The tube heating device according to claim 1, wherein the heating means is provided at least at a longitudinal end portion of the covering.   The tube heating device according to claim 1 or 2, wherein the air flow generation means includes a jet pump provided at an end portion in a longitudinal direction of the covering body.   The tube heating apparatus according to any one of claims 1 to 3, wherein the covering body is provided so that a gap is formed around the entire circumference between the covering body and the heated tube.

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