JP2013036352A - Evaporative fuel processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaporative fuel processing device configured to efficiently improve desorption performance by positively heating the center part of an adsorption chamber while reducing energy loss.SOLUTION: The device includes a canister case 10 containing an adsorption chamber 21 filled with adsorbent 18, a tank port 13 communicating with a fuel tank, a purge port 14 discharging evaporative fuel therethrough, and an atmosphere port 15 communicating with the atmosphere. A heater unit 22 generating heat through energization is arranged in the center part of the adsorption chamber 21 so as not to come into contact with the canister case 10. The heater unit 22 is partitioned by a plurality of heat transfer elements 23 in parallel with a gas flow direction in the adsorption chamber 21, and formed in a honeycomb shape having a cross-sectional shape with a plurality of cells 24. The heater unit 22 occupies a range of 10-50% with respect to a cross sectional area in a direction orthogonal to the gas flow direction in the adsorption chamber 21. The cells 24 are filled with the adsorbent 18.

Description

  The present invention relates to an evaporated fuel processing apparatus filled with an adsorbent that selectively adsorbs and desorbs evaporated fuel.

  Conventionally, in a vehicle that uses highly volatile fuel such as gasoline or light oil as fuel, the evaporative fuel is selectively adsorbed and desorbed to prevent the fuel tank from being damaged by the evaporative fuel generated in the fuel tank. A canister is mounted as an evaporative fuel processing apparatus filled with an adsorbent made of a porous material. In this type of adsorbent, the lower the temperature, the higher the adsorption performance (adsorption amount), and the higher the temperature, the lower the adsorption performance, in other words, the higher the desorption performance (the remaining amount of evaporated fuel decreases). It is generally known that it has the following characteristics. However, when evaporative fuel is desorbed, the adsorbent is cooled by the heat of vaporization, which causes a problem that desorption performance is deteriorated.

  Thus, as a canister for solving such a problem, for example, there is Patent Document 1 below. The canister of Patent Document 1 includes a canister case having an adsorption chamber filled with an adsorbent therein, a tank port communicating with the fuel tank, a purge port from which evaporated fuel desorbed from the adsorbent is discharged, An atmospheric port in communication with the atmosphere. A heating unit composed of a heater plate that generates heat when energized is arranged in parallel with the gas flow direction in the adsorption chamber, and the adsorbent is filled so that the entire region thereof is within 25 mm from the heating unit. Specifically, the heating means has a lattice shape having a plurality of cells by the partition walls, and each cell is filled with an adsorbent. Note that the outer peripheral surface of the heating means is in contact with the peripheral wall of the canister case.

JP 2001-182632 A

  However, in Patent Document 1, since the heating means is in contact with the peripheral wall of the canister case, the heating temperature is easily radiated to the outside of the canister, resulting in a large energy loss. Moreover, since the adsorbent has a low thermal conductivity and tends to generate heat of vaporization at the central portion of the adsorption chamber, it is desirable to heat the central portion of the adsorption chamber more actively. It is only heated as a whole, and does not particularly correspond to the above tendency in the adsorption chamber.

  Accordingly, the present invention provides an evaporative fuel processing apparatus that solves the above-described problems and can efficiently improve desorption performance by actively heating the central portion of the adsorption chamber while reducing energy loss. For the purpose.

  As a means for that, the present invention includes a case having an adsorption chamber filled with an adsorbent made of a porous material that selectively adsorbs and desorbs evaporated fuel, a tank port communicated with a fuel tank, An evaporative fuel processing apparatus comprising a purge port for discharging evaporative fuel desorbed from an adsorbent and an atmospheric port communicating with the atmosphere, wherein a heating portion that generates heat by energization is provided in a central portion of the adsorption chamber Means are arranged so as not to contact the case. The heating means is partitioned by a plurality of partition walls parallel to the gas flow direction in the adsorption chamber, and the cross-sectional shape in a direction perpendicular to the gas flow direction has a lattice shape having a plurality of cells. And the said heating means occupies the range of 10 to 50% with respect to the cross-sectional area of the direction orthogonal to the gas flow direction of the said adsorption | suction chamber, It is characterized by the above-mentioned. Each adsorbent is filled in each cell.

  According to this, the evaporation part by the evaporative fuel processing device is heated by positively heating the central part of the adsorption chamber where the heat of vaporization is likely to be generated and the desorption performance is likely to be lower than the peripheral part (evaporation fuel is liable to remain). Fuel processing capacity is improved. At this time, since the heating means is arranged so as not to come into contact with the case, the heating temperature is unlikely to be dissipated outside the fuel vapor processing apparatus. Thereby, desorption performance can be improved while reducing energy loss. Also, if the power is constant, if the heating range is wide, the energy is dispersed and the calorific value per unit area is reduced, but if the heating range is narrow, the energy is concentrated and the calorific value per unit area is large. Become. Therefore, if the heating means occupies a range of 10 to 50% with respect to the cross-sectional area of the adsorption chamber, the desorption capability at the central portion of the adsorption chamber can be effectively improved. In addition, if each cell in the heating means is also filled with an adsorbent, the adsorbent capacity (the amount of adsorbed evaporative fuel) increases, thereby increasing the absolute processing capacity of the evaporative fuel by the evaporative fuel processing device. Can be improved. At this time, since each cell is parallel to the gas flow direction in the adsorption chamber, the gas fluidity is not hindered by the partition wall of the heating means, and a decrease in the processing efficiency of the evaporated fuel can be avoided.

  The heating means is preferably arranged concentrically with the adsorption chamber (having the same central axis), and the outer shape of the heating means and the inner shape of the adsorption chamber are preferably similar. According to this, since the distance from the case to the heating means is constant over the entire circumference, the central portion of the adsorption chamber is heated uniformly, so that the desorption performance can be improved more effectively and the energy loss is also effective. Can be reduced.

  The heating means can be constituted by a plate-like heat transfer body having a higher thermal conductivity than the adsorbent and forming the partition wall, and a heating element arranged along the heat transfer body. In this case, it is preferable that the heating element is arranged at a position where the central portion of the heating means is most heated. According to this, it is energy-saving compared with the case where the heating means is heated as a whole, and the heating range is more concentrated, so that the desorption performance can be improved more effectively. Note that the heat from the heating element travels through the heat transfer body having a good thermal conductivity and reaches the entire heating means.

  The heating means may be provided with a plurality of layers inside and outside through an adsorbent layer, and the heating timing of each heating means can be controlled independently. For example, the initial stage of desorbing the evaporated fuel from the adsorbent can be controlled such that heating is performed only by the innermost layer heating means, and then heating by the heating means is sequentially started from the inner layer side to the outer layer side. According to this, since the inside of the adsorption chamber can be accurately heated according to the remaining state of the evaporated fuel, the desorption performance can be improved efficiently.

  In addition, an atmospheric temperature sensor that detects the atmospheric temperature and an adsorbent temperature sensor that detects the temperature of the adsorbent that is in contact with the inner peripheral surface of the case, and the temperature detected by the adsorbent temperature sensor is the atmospheric temperature. It is also preferable to reduce the energization amount to the heating means when the temperature is higher than the temperature detected by the sensor. When the adsorbent is heated above the atmospheric temperature by the heating means, the adsorbent is cooled by the atmosphere (the heating temperature is radiated to the outside), so that energy loss occurs. Therefore, if the energization amount is reduced when the temperature of the outermost layer in the adsorption chamber, that is, the adsorbent in contact with the case becomes equal to or higher than the atmospheric temperature, the energy loss can be accurately reduced. Note that if the energization amount is reduced, the heat generation amount of the heating means is also reduced, so that the temperature of the adsorbent in the outermost layer region is constant or lowered.

  According to the present invention, desorption performance can be improved efficiently by positively heating the central portion of the adsorption chamber while reducing energy loss.

1 is a longitudinal sectional view of a canister according to Embodiment 1. FIG. It is the II-II sectional view taken on the line of FIG. 6 is a longitudinal sectional view of a canister according to Embodiment 2. FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is a graph which shows the relationship between the range which a heater unit occupies, and detachment | desorption performance. It is a graph which shows the relationship between the range which a heater unit occupies, and detachment | desorption performance. It is a graph which shows the relationship between the range which a heater unit occupies, and detachment | desorption performance. It is a graph which shows the relationship between the range which a heater unit occupies, and detachment | desorption performance. It is a graph which shows the relationship between the range which a heater unit occupies, and detachment | desorption performance. It is a graph which shows the relationship between the range which a heater unit occupies, and energy loss. It is a graph which shows the relationship between the range which a heater unit occupies, and heating efficiency. 6 is a cross-sectional view of a canister according to Embodiment 3. FIG. It is a related figure which shows the electricity supply timing of each heater unit. It is a cross-sectional view of Modification 1 of the heater unit. It is a cross-sectional view of Modification 2 of the heater unit. It is a cross-sectional view of Modification 3 of the heater unit. It is a cross-sectional view of Modification 4 of the heater unit.

  Hereinafter, typical embodiments of the present invention will be described. The evaporative fuel processing apparatus of the present invention is an apparatus that processes evaporative fuel generated from a fuel tank of a vehicle that uses highly volatile fuel such as gasoline and light oil as fuel, and is generally called a canister. In the following description, for convenience of explanation, the vertical and horizontal directions of the canister are appropriately defined, but these directions also change according to the installation direction of the canister.

(Embodiment 1)
As shown in FIG. 1, the canister 1 includes a hollow canister case 10 made of a synthetic resin and having a hollow rectangular tube shape, and a cover 11 made of a synthetic resin that closes the bottom opening of the canister case 10. The canister case 10 and the cover 11 are formed of the same material such as nylon, and are joined by, for example, vibration welding or adhesion in a state where the flanges 10a and 11a are abutted. The canister case 10 and the cover 11 correspond to the case of the present invention. On the top surface of the canister case 10 (the left surface in FIG. 1), there are a cylindrical tank port 13 that serves as an evaporative fuel introduction section and a cylindrical purge port 14 that discharges the desorbed evaporative fuel. These are integrally formed so as to penetrate inside and outside. On the other hand, on the cover 11 opposite to the tank port 13 and the like, a cylindrical atmospheric port 15 that communicates with the atmosphere and serves as an inlet / outlet of the atmosphere (air) is integrally formed so as to penetrate inside and outside. Thereby, the canister 1 has one adsorption chamber 21 in which a substantially straight gas flow path extending between the tank port 13 and the purge port 14 and the atmospheric port 15 is formed. Although not shown, the tank port 13 communicates with the upper part of the fuel tank, and the purge port 14 communicates with the intake pipe of the engine (internal combustion engine) or is driven and controlled independently of the engine drive. The fuel tank communicates with the suction pump.

  Near the tank port 13 (purge port 14) and the atmosphere port 15 in the canister case 10, air-permeable filters 17 and 17 are arranged, respectively, and the space between the filters 17 and 17 is an adsorption chamber. 21. The adsorbing chamber 18 is filled with the adsorbent 18 capable of selectively adsorbing / desorbing the evaporated fuel, and the heating chamber generates heat by energization in the central portion of the adsorbing chamber 21. As shown, a heater unit 22 is arranged. The heater unit 22 corresponds to the heating means of the present invention.

  A breathable plate 19 is disposed on the outer surface of the filter 17 on the atmosphere port 15 side, and a coil spring 20 is disposed between the plate 19 and the cover 11. As a result, the filter 17 and the plate 19 on the atmosphere port 15 side are always urged toward the tank port 13 by the coil spring 20, so that the adsorbent 18 is accommodated and held without variation. As the filter 17, a synthetic resin non-woven fabric or urethane foam is used. As the adsorbent 18, a porous body having a large number of pores capable of adsorbing and holding evaporated fuel molecules is used, and typically activated carbon is used. For the plate 19, a punching metal or a metal mesh having a large number of pores is used.

  As shown in FIG. 2, the heater unit 22 is partitioned by a plurality of partition walls parallel to the gas flow direction in the adsorption chamber 21, and a lattice having a plurality of cells 24 in a cross-sectional shape perpendicular to the gas flow direction. The plate-like heat transfer body 23 has a shape and has a higher thermal conductivity than the adsorbent 18 and forms a partition wall, and a flexible sheet-like heat generation body 25 arranged along the heat transfer body 23. In the first embodiment, the heater unit 22 has a honeycomb shape, and the adsorbent 18 is densely filled in each cell 24. The heat transfer body 23 is not particularly limited as long as it has a higher thermal conductivity than that of the adsorbent 18. For example, the heat transfer body 23 is made of a metal having a good thermal conductivity such as aluminum, copper, iron, or an alloy thereof. Any material having a higher thermal conductivity than the adsorbent 18 may be used. As the heating element 25, a known heating element that generates heat when energized can be used without particular limitation. For example, a sheet in which a metal foil such as a nickel alloy or a heating wire such as a nichrome wire is placed on an insulating film made of polyimide or the like, or a thermosetting made of a conductive resin containing carbon or silver on the insulating film. A sheet in which a heating element ink layer of a mold is laminated can be used. Although not shown, an energization cable is connected to the heating element 25.

  The heater unit 22 is arranged concentrically with the canister case 10 (adsorption chamber 21), and is not in contact with the canister case 10. Specifically, the gas flow direction in the adsorption chamber occupies substantially the entire adsorption chamber 21 (see FIG. 1), but with respect to the cross-sectional area in the direction perpendicular to the gas flow direction in the adsorption chamber 21 (cross section). Thus, the heater unit 22 is set to a size that occupies a range of 10 to 50%. Note that “the heater unit 22 occupies a range of 10 to 50%” means an existing range of the heater unit 22, that is, a range surrounded by the heater unit 22. At this time, the presence of the adsorbent 18 in each cell 24 is irrelevant. That is, it is a numerical value defined irrespective of whether or not the adsorbent 18 is filled in each cell. If the size of the heater unit 22 is less than 10% of the cross-sectional area of the adsorption chamber 21, the adsorption chamber 21 cannot be heated accurately. On the other hand, if the size of the heater unit 22 exceeds 50% with respect to the cross-sectional area of the adsorption chamber 21, the possibility of energy loss increases, and the energy is dispersed and heating efficiency is reduced with the same power. If the amount of purge air is a relatively small vehicle such as a small car or a hybrid car, the heater unit 22 is preferably as small as possible (for example, about 10 to 20% with respect to the cross-sectional area of the adsorption chamber 21). On the other hand, if the vehicle generates a large amount of evaporated fuel, such as a large vehicle, the heater unit 22 is preferably large (for example, about 40 to 50% of the cross-sectional area of the adsorption chamber 21). .

  Further, the outer shape of the heater unit 22 and the inner shape of the canister case 10 are similar, and the heating element 25 is arranged at a position where the central portion of the heater unit 22 is most heated. For example, although the heating element 25 can be arranged simply on the partition wall located at the true center of the heater unit 22, in the first embodiment, to the partition wall located on both sides of the true center partition wall of the heater unit 22, Arranged so as to sandwich the central partition wall. As a result, the central portion of the heater unit 22 is heated most by the two heating elements 25, and the heat transfer is favorably conducted to the periphery of the heater unit 22.

  Next, the operation of the canister 1 will be described. The evaporated fuel generated in the fuel tank is introduced into the canister 1 from the tank port 13 and flows in the adsorption chamber 21 linearly toward the atmospheric port 15 and is accommodated in the adsorption chamber 21 during that time. It is adsorbed by the adsorbent 18.

  On the other hand, when the inside of the canister 1 becomes negative pressure due to an intake pipe negative pressure, a suction pump, or the like, the atmosphere (outside air) is sucked from the atmosphere port 15 and the evaporated fuel adsorbed on the adsorbent 18 is desorbed (purged). The fluid flows in the opposite direction to the above and is discharged from the purge port 14. At this time, since the heater unit 22 is arranged in parallel with the gas flow direction, the gas fluidity is not hindered.

  The evaporated fuel is vaporized when it is desorbed from the adsorbent 18. Then, the temperature of the adsorbent 18 decreases due to the heat of vaporization of the evaporated fuel, and the desorption capability decreases as it is, and the evaporated fuel remains in the adsorbent 18. In particular, in the central portion of the adsorption chamber 21, the heat of vaporization is not radiated smoothly to the peripheral portion, so that the remaining amount of evaporated fuel tends to increase. Therefore, when evaporating fuel is desorbed, the heating element 25 is energized and the central portion of the adsorption chamber 21 is positively heated by the heater unit 22, thereby suppressing a decrease in the processing capacity of the evaporating fuel. Further, the heater unit 22 occupies 10 to 50% with respect to the cross-sectional area of the adsorption chamber 21 and is not in contact with the canister case 10, so that energy loss is reduced.

(Embodiment 2)
FIG. 3 is a longitudinal sectional view of the canister 3 according to the second embodiment of the present invention, and FIG. 4 is a sectional view taken along line IV-IV in FIG. 3 (transverse sectional view of the canister 3). The canister 3 according to the second embodiment has a plurality of suction chambers therein, and a U-shaped flow path is formed. Specifically, as shown in FIG. 3, a canister case 30 made of a synthetic resin and having a hollow rectangular tube shape and a cover 31 made of a synthetic resin that closes the bottom opening of the canister case 30 are provided. The canister case 30 and the cover 31 correspond to the case of the present invention. The canister case 30 and the cover 31 are formed of the same material such as nylon, and are joined by, for example, vibration welding or adhesion in a state where the flanges 30a and 31a are abutted. On the upper surface of the canister case 30, a tank port 33, a purge port 34, and an atmospheric port 35 are integrally formed in this order. A long partition wall 37 extending vertically from the upper surface of the canister case 30 to the vicinity of the cover 31 is integrally formed between the purge port 34 and the atmospheric port 35. By the partition wall 37, the inside of the canister 3 is partitioned into a first adsorption chamber 38 on the tank port 33 and purge port 34 side and an adsorption chamber on the atmospheric port 35 side. As a result, a U-shaped flow path in which the tank port 33, the purge port 34 and the atmospheric port 35 communicate with each other via the lower side of the partition wall 37 is formed in the canister 3. Further, the adsorption chamber on the atmosphere port 35 side is divided into a second adsorption chamber 39 and a third adsorption chamber 40 by a filter 42. In each of the adsorption chambers 38, 39, and 40, the adsorbent 18 is densely filled throughout.

  Air-permeable plates 41 are also disposed below the first and second adsorption chambers 38 and 39, respectively, and air-permeable filters 42 are disposed on the inside thereof. The plate 41 and the filter 42 are always urged toward the tank port 33 by a coil spring 43 disposed between the plate 41 and the cover 31. Thereby, the adsorbent 18 is accommodated and held without variation. Further, a filter 42 is also arranged on the upper part of the first and third adsorption chambers 38 and 40. As the plate 41 and the filter 42, the same thing as the plate 19 and the filter 17 of Embodiment 1 can be used.

  In addition, the heater unit 22 is arranged concentrically with each of the adsorption chambers 38 and 39 at the center of the first adsorption chamber 38 and the second adsorption chamber 39. As shown in FIG. 4, the heater unit 22 of the second embodiment also has the same configuration as the heater unit 22 of the first embodiment, and has a plurality of partition walls parallel to the gas flow direction in the adsorption chambers 38 and 39. And a flexible sheet-like heating element 25 arranged along the heat transfer body 23. In addition, the cross-sectional shape in the direction orthogonal to the gas flow direction is a honeycomb shape having a lattice shape having a plurality of hexagonal cells 24, and the adsorbent 18 is also closely packed in each cell 24. Further, the heater unit 22 is not in contact with the canister case 30, and the outer shape of the heater unit 22 is similar to the inner shape of the suction chambers 38 and 39. Further, the heater unit 22 occupies a range of 10 to 50% with respect to the cross-sectional area of each suction chamber 38 and 39.

  In the second embodiment, the basic operation is the same as in the first embodiment except that the evaporated fuel and air flow in a U-shape in the canister 3 and are sequentially processed in the adsorption chambers 38 to 39. Detailed description is omitted.

(Test 1)
The relationship between the range (size) occupied by the heater unit and the detachment performance was evaluated using a model canister in which a linear flow path is formed as in Embodiment 1. The model canister was filled with BAX-1500, an activated carbon manufactured by Mead West Beco, for an activated carbon capacity of 2.1 L. 100% gas of n-butane was used as a simulated evaporative fuel, at the time of adsorption: 2 g breakthrough, purge flow rate: 30 L / min, and heating power: 70 W. In addition, various purge amounts [B. V], the desorption performance in the state where the evaporated fuel was desorbed was measured. The results are shown in FIGS. The purge amount [B. V] is a value obtained by dividing the amount of desorption air introduced into the canister by the activated carbon capacity. For example, when 210 L of desorption air is introduced for an activated carbon capacity of 2.1 L, the purge amount [B. V] is 100 [B. V].

  As is apparent from the results of FIGS. 5 to 9, the smaller the purge amount, the higher the desorption efficiency when the heating range at the center of the adsorption chamber, that is, the range occupied by the heater unit with respect to the cross-sectional area of the adsorption chamber is higher. It was found that the unit is preferably 50% or less with respect to the cross-sectional area of the adsorption chamber even if it is large.

(Test 2)
Next, using the same model canister as in Test 1, the temperature of the case surface and the temperature at the center of the adsorption chamber when adsorbed and desorbed under the same conditions were measured. The temperature result of the case surface is shown in FIG. 10, and the temperature result at the center of the adsorption chamber is shown in FIG. From the results shown in FIG. 10, there is no energy loss if the heating range in the central portion of the adsorption chamber is 50% or less. However, when the heating range is 60%, the temperature of the case surface is higher than the atmospheric temperature, and energy loss due to heat dissipation is reduced. It has been confirmed that this occurs. On the other hand, from the result of FIG. 11, it was confirmed that when the heating power is constant, the heating efficiency in the central portion of the adsorption chamber is higher when the heating range is smaller.

  From the above results, it was found that the range occupied by the heating means should be 10 to 50% with respect to the cross-sectional area in the direction orthogonal to the gas flow direction of the adsorption chamber.

(Embodiment 3)
FIG. 12 shows a canister 1 according to the third embodiment. Since the basic configuration of the canister 1 of the third embodiment is the same as that of the canister 1 of the first embodiment, the same reference numerals are given to the same members and the description thereof is omitted, but the arrangement position of the heater unit 22 is different, and the adsorption A plurality of layers are arranged inside and outside through the material layer 18s. Specifically, as shown in FIG. 12, a central heater unit 22a disposed in the central portion of the adsorption chamber 21, an intermediate heater unit 22b disposed so as to surround the central heater unit 22b, and an outer side of the intermediate heater unit 22b are surrounded. An outermost heater unit 22c is disposed, and an adsorbent layer 18s filled with only the adsorbent 18 is interposed between the heater units 22a, 22b, and 22c. Each heater unit 22a, 22b, 22c is provided with a heating element 25 on the center side. That is, in the central heater unit 22a, the heating element 25 is disposed on the central wall, and in the intermediate heater unit 22b and the outermost heater unit 22c, the heating element 25 is disposed on the inner surface side.

  The heating timings of the heater units 22a, 22b, and 22c can be independently controlled by an ECU (engine control unit) (not shown). Specifically, as shown in FIG. 13, at the beginning of the desorption of the evaporated fuel, the inside of the adsorption chamber 21 is heated only by the central heater unit 22a, and then the inner layer is transferred from the intermediate heater unit 22b to the outermost heater unit 22c. The energization heating is started sequentially from the side to the outer layer side.

  In this way, by controlling the energization timing to the heater units 22a, 22b, and 22c, the desorption performance can be accurately improved while avoiding energy loss at the initial stage of desorption with a large amount of evaporated fuel. On the other hand, in the latter stage of desorption when the amount of evaporated fuel is reduced, the adsorption chamber 21 is heated as a whole, so that it is possible to reliably avoid the remaining evaporative fuel in the periphery. At this time, there is a concern about energy loss, but since it is only for a short time in the late stage of desorption, even if energy loss occurs, it can be suppressed to a very small amount.

  The energization timing control to each of the heater units 22a, 22b, and 22c is performed based on the elapsed time from the start of desorption of the evaporated fuel, or the evaporated fuel concentration by the evaporated fuel concentration sensor provided near the purge port 14. On the basis of the decrease in the air flow rate, or on the basis of the cumulative purge air amount by the gas flow meter provided in the vicinity of the atmospheric port 15. Alternatively, control can be performed by identifying the evaporated fuel concentration from the purge air amount or the like based on a calculation formula stored in advance in the ECU.

(Embodiment 4)
In the first to third embodiments, the canister is further provided with an atmospheric temperature sensor that detects the atmospheric temperature and an adsorbent temperature sensor that detects the temperature of the adsorbent that is in contact with the inner peripheral surface of the canister case. It is also preferable to perform control so that the amount of current supplied to the heater unit is reduced when the temperature detected by the temperature becomes equal to or higher than the temperature detected by the atmospheric temperature sensor. Thereby, energy loss can be reduced reliably. In the case of the third embodiment, the energization amount to all the heater units 22a, 22b, and 22c can be reduced uniformly, but the energization can also be stopped preferentially from the heater unit side on the outer layer side.

  The detection signals from the atmospheric temperature sensor and the adsorbent temperature sensor are transmitted to the ECU, and the ECU controls the energization amount to the heater unit based on the detection signals. The installation position of the atmospheric temperature sensor is not particularly limited as long as it can detect the atmospheric temperature, and the adsorbent temperature sensor may be provided on the inner surface of the canister case.

(Other variations)
As mentioned above, although the typical embodiment of this invention was described, it is not limited to this, A various deformation | transformation is possible in the range which does not deviate from the summary of this invention. The heater unit 22 is not limited to a honeycomb shape, but is defined by a heat transfer body 23 having a plurality of partition walls parallel to the gas flow direction in the adsorption chamber, and a cross-sectional shape in a direction orthogonal to the gas flow direction is a plurality of cells 24. As long as it exhibits a lattice shape having, for example, as shown in FIGS. Specifically, each cell 24 is partitioned so as to be rectangular as in Modification 1 shown in FIG. 14, or each cell 24 is partitioned so as to be triangular as in Modification 2 shown in FIG. 16, a plurality of heat transfer bodies 23 can be arranged side by side in only one direction as in Modification 3 shown in FIG. 16, or unevenness can be provided in each heat transfer body 23 as in Modification 4 shown in FIG. 17. . In addition, in each modification shown in FIGS. 14-17, the outer frame surrounding an outer periphery does not necessarily represent the heat transfer body 23, but shows the range which a heater unit occupies.

  In the case of having a plurality of adsorption chambers as in the second and third embodiments, the heater unit may be arranged only in one of the adsorption chambers, or the heater units may be arranged in all the adsorption chambers. it can. When arranging the heater units in some adsorption chambers, it is preferable to arrange them preferentially from the tank port side which is the most upstream side in the gas flow direction when adsorbing evaporated fuel.

  In the third embodiment, the heater unit is provided with three layers inside and outside, but two layers may be provided, or four or more layers may be provided.

1.3 Canister 10/30 Canister case 11/31 Cover 13/33 Tank port 14/34 Purge port 15/35 Atmospheric port 18 Adsorbent 17/42 Filter 19/41 Plate 20/43 Coil spring 21/38/39 / 40 Adsorption chamber 22 Heater unit 23 Heat transfer element 24 Cell 25 Heating element

Claims (6)

A case provided with an adsorption chamber filled with an adsorbent made of a porous material that selectively adsorbs and desorbs evaporated fuel, a tank port communicating with the fuel tank, and evaporated fuel desorbed from the adsorbent An evaporative fuel processing apparatus comprising: a purge port from which gas is discharged; and an atmospheric port in communication with the atmosphere,
In the central part of the adsorption chamber, a heating means that generates heat by energization is arranged so as not to contact the case,
The heating means is partitioned by a plurality of partition walls parallel to the gas flow direction in the adsorption chamber, and the cross-sectional shape in a direction perpendicular to the gas flow direction has a lattice shape having a plurality of cells,
The heating means occupies a range of 10 to 50% with respect to a cross-sectional area in a direction orthogonal to the gas flow direction of the adsorption chamber,
The evaporative fuel processing apparatus, wherein the adsorbent is filled in each cell. The heating means is arranged concentrically with the adsorption chamber,
The evaporated fuel processing apparatus according to claim 1, wherein an outer shape of the heating means is similar to an inner shape of the adsorption chamber. The heating means includes a plate-like heat transfer body having a higher thermal conductivity than the adsorbent and forms the partition wall, and a heating element arranged along the heat transfer body,
The evaporative fuel processing apparatus according to claim 1, wherein the heating element is disposed at a position where a central portion of the heating unit is most heated. The heating means is arranged in multiple layers inside and outside through an adsorbent layer,
The evaporative fuel processing apparatus according to any one of claims 1 to 3, wherein the heating timing of each heating means is independently controlled.   5. The evaporated fuel processing apparatus according to claim 4, wherein the initial stage of desorbing the evaporated fuel from the adsorbent is heated only by the heating means of the innermost layer, and then heating by the heating means is sequentially started from the inner layer side to the outer layer side. . An atmospheric temperature sensor for detecting the atmospheric temperature, and an adsorbent temperature sensor for detecting the temperature of the adsorbent in contact with the inner peripheral surface of the case,
The evaporated fuel processing apparatus according to any one of claims 1 to 5, wherein when the temperature detected by the adsorbent temperature sensor is equal to or higher than the temperature detected by the atmospheric temperature sensor, the energization amount to the heating means is reduced.

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