JP2019132190A - Canister - Google Patents

Abstract

To enhance an effect of suppressing a fluid flow from an upstream side to a downstream side at the time of adsorbing evaporative fuel and enhance an effect of suppressing blowing-through evaporative fuel.SOLUTION: A flow passage 17 having a main passage part 18, an auxiliary passage part 19 and a communication passage part 20 is formed inside a case 12. The passage parts 18, 19 are provided with adsorption chambers 30, 31 in which an adsorbent 33 is filled. The communication passage part 20 is arranged at a lower side in the vertical direction in the installation state of the case 12. The case 12 is provided with a first lateral wall 23 that separates between the main passage part 18 and the communication passage part 20, a second lateral wall 24 that separates between the communication passage part 20 and the auxiliary passage part 19, and a plurality of vertical walls 41 that divide the communication passage part 20 into three or more branch chambers 42. A first orifice passage 44 is provided in the first lateral wall 23, a second orifice passage 45 is provided in the second lateral wall 24, and third orifice passages 46 are provided in the vertical walls 41.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a canister. More specifically, the present invention relates to a canister as an evaporative fuel processing device mounted mainly on a vehicle such as an automobile.

  2. Description of the Related Art Conventionally, for example, a canister that temporarily adsorbs evaporated fuel is used to prevent the evaporated fuel from an automobile fuel tank or the like from being released into the atmosphere. An example of the canister is described in Patent Document 1. The canister of Patent Document 1 includes a case having two chambers filled with an adsorbent that adsorbs evaporated fuel, an air introduction port that opens in one of the two chambers, an evaporative fuel introduction port that opens in the other chamber, A purge port and a communication passage communicating the two chambers. The communication passage is provided with a throttle for reducing the passage area. Note that the “atmospheric introduction port”, “evaporated fuel introduction port”, “purge port”, “two chambers”, and “communication passage” in the cited document 1 are respectively referred to as “atmospheric port”, “tank” in this specification. It corresponds to “port”, “purge port”, “communication passage”, “main passage and sub-passage”.

Japanese Patent Laid-Open No. 5-33734

  According to the canister of Patent Document 1, the flow of fluid from the upstream side to the downstream side during the evaporative fuel adsorption is suppressed by only one throttle provided in the communication path. For this reason, the effect of suppressing the flow of the fluid is low, and the effect of suppressing the evaporated fuel blowing through the canister may be insufficient.

  The problem to be solved by the present invention is to provide a canister capable of enhancing the effect of suppressing the flow of fluid from the upstream side to the downstream side during adsorption of evaporated fuel and improving the effect of suppressing evaporated fuel that blows through. It is in.

  The above-described problems can be solved by the canister of the present invention.

  In the first aspect of the present invention, a main passage portion communicating with the tank port and the purge port, a sub passage portion communicating with the atmospheric port, and a communication passage communicating the main passage portion and the sub passage portion are provided inside the case. A U-shaped flow path is formed, and the main passage portion and the sub-passage portion are provided with adsorption chambers filled with an adsorbent that adsorbs evaporated fuel, and the case In the canister, the communication passage portion is disposed on the lower side in the vertical direction in the installed state, wherein the case includes a first horizontal wall that partitions the main passage portion and the communication passage portion, and the communication passage. And a plurality of vertical walls that divide the communication passage portion into three or more compartments, and the main passage is provided on the first horizontal wall. And the most upstream side of the three or more compartments at the time of evaporative fuel adsorption , And the second lateral wall communicates the sub-passage portion with the most downstream compartment of the three or more compartments when the evaporated fuel is adsorbed. The second throttle passage is provided, and the vertical wall is a canister provided with a third throttle passage communicating the adjacent compartments with each other.

  According to the first invention, the fluid flowing from the main passage portion to the sub-passage portion via the communication passage portion is the first throttle passage of the first horizontal wall, the third throttle passage of the plurality of vertical walls, and the second horizontal wall. It passes through the second throttle passage. Therefore, compared with Patent Document 1, the effect of suppressing the flow of fluid from the upstream side to the downstream side at the time of adsorbing the evaporated fuel can be enhanced, and the effect of suppressing the evaporated fuel blowing through the canister can be improved.

  A second invention is a canister according to the first invention, wherein the first throttle passage is formed in a cylindrical shape extending downward from the first lateral wall.

  According to the second aspect of the invention, compared with the case where the first throttle passage is formed in a hole shape, the evaporated fuel having a large specific gravity is likely to be accumulated in the lower part of the uppermost stream side compartment when adsorbing the evaporated fuel, and evaporates downstream. The outflow of fuel can be suppressed.

  A third invention is a canister according to the first or second invention, wherein the third throttle passage is disposed at an upper end portion of the vertical wall.

  According to the third invention, the outflow of the evaporated fuel to the downstream side at the time of adsorbing the evaporated fuel can be suppressed as compared with the case where the third throttle passage is arranged at the vertical center portion or the lower portion of the vertical wall.

  According to a fourth invention, in any one of the first to third inventions, the volume of the downstream compartment when adsorbing the evaporated fuel in the adjacent compartments of the three or more compartments is greater than the volume of the upstream compartment. It is also a canister.

  According to the fourth aspect of the invention, the flow rate of the evaporated fuel flowing in the downstream compartment is lower than the flow rate of the evaporated fuel flowing in the upstream compartment when adsorbing the evaporated fuel. For this reason, the outflow of the evaporative fuel from the downstream compartment to the downstream side during the evaporative fuel adsorption can be suppressed.

  A fifth invention is a canister according to any one of the first to fourth inventions, wherein a plurality of the second throttle passages are arranged in a distributed manner on the second lateral wall.

  According to the fifth invention, it is possible to suppress the stagnation of the evaporated fuel in the most downstream compartment when adsorbing the evaporated fuel, and to uniformize the flow of fluid from the most downstream compartment to the sub-passage. Thereby, the adsorption efficiency of the evaporated fuel in the adsorption chamber of the sub passage portion can be improved.

  A sixth invention is a canister according to any one of the first to fifth inventions, wherein the lower portion of the main passage portion and the communication passage portion are extended to the side opposite to the sub passage portion side.

  According to the sixth invention, the volume of the lower portion of the main passage portion and the communication passage portion can be increased, and the amount of evaporated fuel stored can be increased.

  In a seventh aspect based on any one of the first to sixth aspects, the third throttle passage has a tapered cross section that gradually increases the passage area from the upstream side toward the downstream side when the evaporated fuel is adsorbed. It has a canister.

  According to the seventh invention, it is possible to reduce the ventilation resistance at the time of purging (at the time of desorption of the evaporated fuel) and improve the desorption performance.

  In an eighth aspect based on the first aspect, the case has a first case member having the first horizontal wall and the second horizontal wall, and a plurality of vertical walls and is assembled to the first case member. A second case member, and the third throttle passage is formed in a horizontally long concave groove opening at an upper end portion of the vertical wall, and the third throttle passage includes the first case. A canister in which a filter sandwiched between a member and the second case member is disposed so as to straddle the plurality of vertical walls.

  According to the eighth invention, when the first case member and the second case member are assembled, the filter sandwiched between the two case members is disposed in the third throttle passage so as to straddle the plurality of vertical walls. Can do. Thereby, the assembly | attachment property of a filter can be improved compared with the case where a filter is assembled | attached for every vertical wall.

  According to the canister of the present invention, the effect of suppressing the flow of fluid from the upstream side to the downstream side when adsorbing evaporated fuel can be enhanced, and the effect of suppressing evaporated fuel that blows through can be improved.

2 is a cross-sectional view showing a canister according to Embodiment 1. FIG. 6 is a cross-sectional view showing a canister according to Embodiment 2. FIG. 6 is a cross-sectional view showing a canister according to Embodiment 3. FIG. 6 is a cross-sectional view showing a canister according to Embodiment 4. FIG. 10 is a cross-sectional view showing a canister according to Embodiment 5. FIG. 10 is a cross-sectional view showing a canister according to Embodiment 6. FIG. FIG. 10 is a cross-sectional view showing a canister according to a seventh embodiment. FIG. 10 is a cross-sectional view showing a canister according to an eighth embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[Embodiment 1]
The canister of the present embodiment is a canister having a U-shaped flow structure mounted on a vehicle such as an automobile. FIG. 1 is a cross-sectional view showing a canister. In FIG. 1, the vertical direction corresponds to a so-called vertical direction in a state where the vehicle is mounted on the vehicle.

(Configuration of canister)
As shown in FIG. 1, the canister 10 has a box-shaped resin case 12. The case 12 includes a rectangular tubular tube wall portion 13 that is elongated in the left-right direction, an upper wall portion 14 that closes an upper end surface of the tube wall portion 13, and a lower wall portion 15 that closes a lower end surface of the tube wall portion 13. Have A U-shaped flow path 17 is formed in the case 12. The flow path 17 includes a right main passage 18, a left sub passage 19, and a communication passage 20 that connects the passages 18 and 19 below the main passage 18 and the sub passage 19. Prepare. A fluid (gas containing evaporated fuel) flows through the flow path 17. The communication passage portion 20 is disposed on the lower side in the vertical direction when the case 12 is installed.

  A partition wall 22 is provided between the main passage portion 18 and the sub passage portion 19 to partition both the passage portions 18 and 19. Between the main passage portion 18 and the communication passage portion 20, a first horizontal wall 23 that partitions both passage portions 18 and 20 is provided. Between the sub-passage part 19 and the communication passage part 20, the 2nd horizontal wall 24 which partitions off both the passage parts 19 and 20 is provided. The upper end portion of the main passage portion 18 corresponds to the upstream end of the flow passage 17 when the evaporated fuel is adsorbed, and the upper end portion of the sub passage portion 19 corresponds to the downstream end of the flow passage 17 when the evaporated fuel is adsorbed. The case 12 is configured by thermally joining a plurality of divided bodies divided in the vertical direction by thermal welding of resin.

  A tank port 26 and a purge port 27 communicating with the main passage portion 18 and an atmospheric port 28 communicating with the sub passage portion 19 are formed on the upper wall portion 14 of the case 12. The tank port 26 communicates with an upper air chamber of a fuel tank (not shown). The purge port 27 communicates with the intake passage of the engine via a purge control valve (VSV) (not shown). The opening degree of the purge control valve is controlled by an electronic control unit (ECU), and purge control is performed based on measured values of an A / F sensor or the like during engine operation. The atmospheric port 28 is in communication with the atmosphere.

  The main passage portion 18 is provided with a first adsorption chamber 30, and the sub passage portion 19 is provided with a second adsorption chamber 31. Both adsorbing chambers 30 and 31 are filled with an adsorbent 33 that adsorbs an evaporated fuel component, so-called evaporated fuel, at a predetermined density. In the present embodiment, granular activated carbon is used as the adsorbent 33. As the activated carbon, granulated coal or crushed coal can be used.

  A baffle plate 35 is provided between the tank port 26 and the purge port 27 to partition the upper end portion of the main passage portion 18 to the left and right. As a result, the fluid flowing from the tank port 26 to the purge port 27 passes through the first adsorption chamber 30.

  On both left and right upper end surfaces of the first adsorption chamber 30 partitioned by the baffle plate 35, a filter 36 made of a nonwoven fabric or the like covering the surface is provided. Further, a filter 37 made of urethane or the like that covers the lower end surface of the first adsorption chamber 30 is provided. The filter 37 is overlaid on the first horizontal wall 23.

  A filter 38 made of a nonwoven fabric or the like covering the surface is provided on the upper end surface of the second adsorption chamber 31. Further, a filter 39 made of urethane or the like that covers the lower end surface of the second adsorption chamber 31 is provided. The filter 39 is overlaid on the second lateral wall 24.

  The communication passage portion 20 is provided with a plurality of (for example, three) vertical walls 41 in the fluid flow direction. The three vertical walls 41 partition the communication passage portion 20 into four compartments 42 in four equal parts. Placed in position. The vertical wall 41 on the downstream side (left side in FIG. 1) at the time of adsorbing the evaporated fuel is formed continuously with the partition wall 22. Of the four compartments 42, the rightmost compartment 42 in FIG. 1 corresponds to the most upstream compartment 42 when the evaporated fuel is adsorbed, and the leftmost compartment 42 corresponds to the most downstream compartment 42 when the evaporated fuel is adsorbed. To do. In addition, each compartment 42 is called the 1st compartment 42, the 2nd compartment 42, the 3rd compartment 42, and the 4th compartment 42 toward the downstream from the most upstream side at the time of fuel vapor adsorption.

  The first lateral wall 23 is formed with a first throttle passage 44 that communicates the main passage portion 18 and the first compartment 42 and reduces the passage area. The first throttle passage 44 is formed of a hole penetrating the first lateral wall 23, and is disposed at a position on the right side of the wall portion of the first lateral wall 23 facing the first compartment 42.

  The second horizontal wall 24 is formed with a second throttle passage 45 that communicates the sub passage portion 19 and the fourth compartment 42 and reduces the passage area. The second throttle passage 45 includes a hole penetrating the second lateral wall 24 and is disposed at the center of the second lateral wall 24.

  The vertical wall 41 is formed with a third throttle passage 46 communicating with the adjacent compartments 42. The third throttle passage 46 is formed of a hole penetrating the vertical wall 41 and is disposed at the center of the vertical wall 41.

(Operation of canister 10)
In the above-described canister 10, the evaporated fuel that has flowed into the canister 10 from the tank port 26 is adsorbed by the adsorbent 33 in both adsorption chambers 30 and 31 and then released from the atmospheric port 28 to the atmosphere. At that time, the fluid in the first adsorption chamber 30 flows into the first compartment 42 through the first throttle passage 44 of the first lateral wall 23. The fluid in the first compartment 42 flows to the second compartment 42 through the third throttle passage 46 of the right vertical wall 41. The fluid in the second compartment 42 flows into the third compartment 42 through the third throttle passage 46 of the central vertical wall 41. The fluid in the third compartment 42 flows to the fourth compartment 42 through the third throttle passage 46 of the left vertical wall 41. The fluid in the fourth compartment 42 flows into the second adsorption chamber 31 through the second throttle passage 45 of the second lateral wall 24.

  During purge control during engine operation, a purge control valve is opened by an electronic control unit (ECU). Then, the air sucked into the canister 10 from the atmospheric port 28 due to the negative pressure in the intake passage flows in the direction opposite to that during the adsorption, and then is led out from the purge port 27 to the intake passage of the engine. At that time, the evaporated fuel is desorbed from the adsorbent 33 in each of the adsorption chambers 30 and 31.

(Advantages of canister 10)
According to the canister 10 described above, the fluid flowing from the main passage portion 18 to the sub-passage portion 19 through the communication passage portion 20 flows into the first throttle passage 44 of the first horizontal wall 23 and the third throttle passages 46 of the plurality of vertical walls 41. And through the second throttle passage 45 of the second lateral wall 24. Therefore, compared with Patent Document 1, the effect of suppressing the flow of fluid from the upstream side to the downstream side at the time of adsorbing the evaporated fuel can be enhanced, and the effect of suppressing the evaporated fuel blowing through the canister 10 can be improved. As a result, it is possible to improve the DBL (diurnal breathing loss) performance of the US regulation of the evaporated fuel released from the left vehicle to the atmosphere.

[Embodiment 2]
Since this embodiment adds a change to Embodiment 1 (refer FIG. 1), the changed part is demonstrated and the overlapping description is abbreviate | omitted. FIG. 2 is a cross-sectional view showing the canister. As shown in FIG. 2, the first throttle passage (reference numeral 144) of the first horizontal wall 23 is formed in a cylindrical shape that extends downward from the first horizontal wall 23.

  According to the present embodiment, the evaporated fuel having a large specific gravity is formed in the lower portion of the first compartment 42 as compared with the case where the first throttle passage is formed in a hole shape (the first throttle passage 44 of the first embodiment (see FIG. 1)). Is easy to accumulate, and the outflow of the evaporated fuel to the downstream side when the evaporated fuel is adsorbed can be suppressed.

[Embodiment 3]
Since this embodiment adds a change to Embodiment 1 (refer FIG. 1), the changed part is demonstrated and the overlapping description is abbreviate | omitted. FIG. 3 is a cross-sectional view showing the canister. As shown in FIG. 3, the third throttle passage 46 is disposed at the upper end of the vertical wall 41.

  According to the present embodiment, compared to the case where the third throttle passage 46 is disposed at the vertical center or lower portion of the vertical wall 41, the outflow of the evaporated fuel to the downstream side when the evaporated fuel is adsorbed can be suppressed. .

[Embodiment 4]
Since this embodiment adds a change to Embodiment 1 (refer FIG. 1), the changed part is demonstrated and the overlapping description is abbreviate | omitted. FIG. 4 is a sectional view showing the canister. As shown in FIG. 4, regarding the first to third compartments 42 of the communication passage portion 20, the volume of the adjacent compartments 42 is larger in the downstream compartment 42 than in the upstream compartment 42 when the evaporated fuel is adsorbed. That is, in FIG. 4, when the volume of the first compartment 42 is V1, the volume of the second compartment 42 is V2, and the volume of the third compartment 42 is V3,
V1 <V2 <V3
The volumes of the first to third compartments 42 are set so as to satisfy the above relationship.

  According to this embodiment, the flow rate of the evaporated fuel flowing through the second compartment 42 is lower than the flow rate of the evaporated fuel flowing through the first compartment 42. For this reason, the outflow of the evaporated fuel from the second compartment 42 to the third compartment 42 can be suppressed. Further, in FIG. 4, the flow rate of the evaporated fuel flowing through the third compartment 42 is lower than the flow rate of the evaporated fuel flowing through the second compartment 42. For this reason, the outflow of the evaporated fuel from the third compartment 42 to the fourth compartment 42 can be suppressed.

[Embodiment 5]
Since this embodiment adds a change to Embodiment 1 (refer FIG. 1), the changed part is demonstrated and the overlapping description is abbreviate | omitted. FIG. 5 is a cross-sectional view showing the canister. As shown in FIG. 5, a large number of second throttle passages (reference numerals 145) are distributed on the second lateral wall 24. That is, the second lateral wall 24 is formed in a porous plate shape.

  According to this embodiment, the stagnation of the evaporated fuel in the fourth compartment 42 can be suppressed, and the flow of fluid from the fourth compartment 42 to the sub passage portion 19 can be made uniform. Thereby, the adsorption efficiency of the evaporated fuel in the adsorption chambers 30 and 31 of the sub passage portion 19 can be improved.

[Embodiment 6]
Since this embodiment adds a change to Embodiment 1 (refer FIG. 1), the changed part is demonstrated and the overlapping description is abbreviate | omitted. FIG. 6 is a sectional view showing the canister. As shown in FIG. 6, the lower part 18a of the main channel | path part 18 and the communication channel | path part 20 are expanded to the opposite side to the sub channel | path part 19 side. Thereby, the volume of the lower part 18a of the main channel | path part 18 and the communication channel | path part 20 is increased. In connection with this, each volume of the 1st-3rd compartment 42 of the communication channel | path part 20 is also increased.

  According to this embodiment, the volume of the lower part 18a of the main channel | path part 18 and the communication channel | path part 20 can be increased, and the storage amount of evaporative fuel can be increased.

[Embodiment 7]
Since this embodiment adds a change to Embodiment 1 (refer FIG. 1), the changed part is demonstrated and the overlapping description is abbreviate | omitted. FIG. 7 is a cross-sectional view showing the canister. As shown in FIG. 7, the third throttle passage (referenced by 146) has a tapered cross section that gradually increases the passage area from the upstream side to the downstream side when adsorbing the evaporated fuel.

  According to the present embodiment, it is possible to reduce the ventilation resistance at the time of purging (at the time of desorption of evaporated fuel) and improve the desorption performance.

[Embodiment 8]
Since this embodiment adds a change to Embodiment 1 (refer FIG. 1), the changed part is demonstrated and the overlapping description is abbreviate | omitted. FIG. 8 is a cross-sectional view showing the canister. As shown in FIG. 8, the case 12 includes a first case member 12a having a first horizontal wall 23 and a second horizontal wall 24, and a second case member having three vertical walls 41 and assembled to the first case member 12a. 12b. The case 12 is divided into a first case member 12a and a second case member 12b on a single plane including the lower surfaces of the first horizontal wall 23 and the second horizontal wall 24.

  The third throttle passage (denoted by reference numeral 246) is formed in a horizontally long concave groove opening at the upper end of the vertical wall 41. A band plate-like filter 48 that is sandwiched between the first case member 12a and the second case member 12b is disposed in the third throttle passage 246. The filter 48 is disposed so as to straddle the three vertical walls 41. The filter 48 is made of urethane or the like.

  According to the present embodiment, when the first case member 12a and the second case member 12b are assembled, the filter 48 sandwiched between the case members 12a and 12b is arranged so as to straddle the three vertical walls 41. It can be arranged in the throttle passage 246. Thereby, compared with the case where the filter 48 is assembled | attached for every vertical wall 41, the assembly | attachment property of the filter 48 can be improved.

[Other Embodiments]
The present invention is not limited to the above-described embodiments, and modifications can be made without departing from the present invention. For example, the present invention may be applied to a canister having a plurality of adsorption chambers in the main passage portion 18 and / or the sub passage portion 19. Moreover, the number of the compartments 42 should just be at least 3 or more rooms. Further, the arrangement position of the vertical wall 41 may be arbitrarily set. Further, although the vertical wall 41 on the most downstream side at the time of evaporating fuel adsorption is formed so as to be continuous with the partition wall 22, it may not be continuous with the partition wall 22. Further, one or more vertical walls 41 may be arranged at a position corresponding to the second horizontal wall 24. In addition, the shape, size, number, arrangement position, and the like of each throttle passage of the first throttle passage, the second throttle passage, and the third throttle passage may be changed. The first horizontal wall 23 and / or the second horizontal wall 24 may be provided so as to be movable in the vertical direction, and may be biased upward by a biasing means (not shown) such as a spring. Moreover, the vertical wall 41 should just be 1 or more. The filter 48 may be provided so as to cover the first throttle passage 44 and / or the second throttle passage 45.

DESCRIPTION OF SYMBOLS 10 Canister 12 Case 17 Flow path 18 Main passage part 19 Sub-passage part 20 Communication passage part 23 1st side wall 24 2nd side wall 26 Tank port 27 Purge port 28 Atmospheric port 30 1st adsorption chamber 31 2nd adsorption chamber 33 Adsorbent 41 Vertical wall 42 Branch chamber 44 First throttle passage 45 Second throttle passage 46 Third throttle passage 48 Filter 144 First throttle passage 145 Second throttle passage 146 Third throttle passage 246 Third throttle passage

Claims (8)

The case includes a main passage portion communicating with the tank port and the purge port, a sub passage portion communicating with the atmospheric port, and a communication passage portion communicating with the main passage portion and the sub passage portion. A letter-shaped channel is formed,
The main passage portion and the sub passage portion are provided with adsorption chambers filled with an adsorbent that adsorbs evaporated fuel,
The canister is disposed in the vertical direction lower side in the installation state of the case,
The case includes a first lateral wall that partitions the main passage portion and the communication passage portion, a second lateral wall that partitions the communication passage portion and the sub-passage portion, and three communication passage portions. A plurality of vertical walls that divide into the above compartments,
The first lateral wall is provided with a first throttle passage that communicates the main passage portion and the most upstream compartment at the time of evaporative fuel adsorption among the three or more compartments.
The second lateral wall is provided with a second throttle passage that communicates the sub-passage portion and the most downstream compartment at the time of evaporative fuel adsorption among the three or more compartments.
The canister, wherein the vertical wall is provided with a third throttle passage that allows adjacent compartments to communicate with each other. The canister according to claim 1,
The canister, wherein the first throttle passage is formed in a cylindrical shape extending downward from the first lateral wall. The canister according to claim 1 or 2,
The canister, wherein the third throttle passage is disposed at an upper end portion of the vertical wall. The canister according to any one of claims 1 to 3,
A canister in which the volume of the downstream compartment when adsorbing fuel vapor is larger than the volume of the upstream compartment in the adjacent compartments of the three or more compartments. A canister according to any one of claims 1 to 4,
A large number of the second throttle passages are distributed on the second lateral wall. A canister according to any one of claims 1 to 5,
The canister, wherein a lower portion of the main passage portion and the communication passage portion are extended to a side opposite to the sub passage portion side. The canister according to any one of claims 1 to 6,
The third throttle passage has a tapered cross section that gradually increases the passage area from the upstream side toward the downstream side when adsorbing evaporated fuel. The canister according to claim 1,
The case includes a first case member having the first horizontal wall and the second horizontal wall, and a second case member having the plurality of vertical walls and assembled to the first case member.
The third throttle passage is formed in a horizontally long concave groove opening at the upper end of the vertical wall,
A canister, wherein a filter sandwiched between the first case member and the second case member is disposed in the third throttle passage so as to straddle the plurality of vertical walls.

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