JP6475996B2 - Defrost heater and refrigerator - Google Patents

Description

  The present invention relates to a defrosting heater for removing frost generated in a cooler and a refrigerator provided with the same.

  JP, 2014-142126, A (patent documents 1) etc. are mentioned as literature in which a defrost heater which defrosts frost adhering to a cooler was indicated.

  A defrosting device disclosed in Patent Document 1 includes a glass tube, a plug that covers both ends of the glass tube, a heating element (heater wire) that is disposed inside the glass tube and has a plurality of wire diameters and is wound. Is provided. The heating element is provided so that the amount of heat generated per unit length differs in each section according to the amount of frost formation in each section of the cooler by including portions with different wire diameters.

JP 2014-142126 A

  However, in the defrosting heater disclosed in Patent Document 1, since the heating element is configured by caulking by overlapping the ends of heater wires having different wire diameters, manufacturing is complicated. Moreover, there is a concern that the heating element may be disconnected due to a problem of the caulking portion.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a defrost heater having a simple configuration and good defrosting efficiency, and a refrigerator equipped with the same. There is.

The defrost heater based on this invention is a defrost heater which defrosts the frost adhering to the cooler which produces | generates cold air | atmosphere, Comprising: The sealing member which seals the both ends of the said glass tube, The said glass A heater wire made of a metal resistor wound in a coil and installed in a tube, the heater wire having a substantially the same wire diameter and a narrow pitch portion with a narrow winding interval, and the narrow wire And a wide pitch portion having a winding interval wider than that of the pitch portion. A movement preventing portion for preventing the boundary between the narrow pitch portion and the wide pitch portion from moving in the axial direction of the glass tube is provided at a boundary portion between the narrow pitch portion and the wide pitch portion.

In the defrost heater based on the said invention, the said movement prevention part may be provided so that a frictional force may act in contact with the inner surface of the said glass tube.

In the defrost heater based on the said invention , the said movement prevention part may be comprised by the rib which protrudes in the radial direction from the inner surface of the said glass tube.

  In the defrosting heater according to the present invention, it is preferable that the narrow pitch portion is disposed on each of both ends of the glass tube, and the wide pitch portion is disposed between the two narrow pitch portions. .

  The refrigerator based on 1st aspect based on this invention was provided in the defrost heater in any one of said, the refrigerator compartment separated from the freezer compartment and the said freezer compartment, and the back side of the said freezer compartment. A cooling duct and a return duct for sending the air in the refrigerating room to the cooling room, wherein the cooler is disposed in the cooling room, and the air taken into the cooling room from the freezing room and the return duct A refrigerant pipe extending in the vertical direction of the cooling chamber while meandering and cooling the air returning from the return port to the cooling chamber, the return port being at least one side surface side of the cooler located in the left-right direction The heater wire includes the narrow pitch portion on the side close to the return port and the wide pitch portion on the side far from the return port.

  A refrigerator according to a second aspect based on the present invention includes a defrost heater described above, a freezer compartment, a refrigerator compartment separated from the freezer compartment, and a cooling compartment provided on the back side of the freezer compartment. A return duct that sends the air in the refrigerating chamber to the cooling chamber, and the cooler is disposed in the cooling chamber, and the air taken into the cooling chamber from the freezer and the return port of the return duct Cooling the air returning from the cooling chamber to the cooling chamber and including a refrigerant pipe extending in the vertical direction of the cooling chamber while meandering, and the return port is disposed on at least one opposing surface side of the cooler positioned in the front-rear direction In addition, it is provided so as to extend in the left-right direction, the narrow pitch portion is disposed on each of both ends of the glass tube, and the wide pitch portion is disposed between the two narrow pitch portions.

  ADVANTAGE OF THE INVENTION According to this invention, a defrost heater with favorable defrost efficiency and a refrigerator provided with this can be provided.

2 is a schematic cross-sectional view of a refrigerator according to Embodiment 1. FIG. It is a figure which shows the movement of the air in the refrigerator shown in FIG. It is a schematic diagram of the defrost heater which concerns on Embodiment 1. FIG. It is a schematic diagram of the defrost heater which concerns on Embodiment 2. FIG. It is a figure which shows the movement of the air in the refrigerator which concerns on Embodiment 3. FIG. It is a schematic diagram of the defrost heater which concerns on Embodiment 3. FIG. It is a figure which shows the temperature distribution along the axial direction of the defrost heater shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the same or common parts are denoted by the same reference numerals in the drawings, and description thereof will not be repeated.

(Embodiment 1)
(Structure of the refrigerator)
First, the refrigerator according to Embodiment 1 of the present invention will be described. A refrigerator is a device for cooling stored items (objects to be cooled) such as foods by a refrigeration cycle, for example, a refrigerator-freezer used in a home or the like. The refrigerator in the present embodiment includes a freezing room for storing the object to be cooled in a frozen state, and a refrigeration room for storing the object to be cooled.

  FIG. 1 is a schematic cross-sectional view of a refrigerator according to the present embodiment. FIG. 2 is a diagram illustrating movement of air in the refrigerator illustrated in FIG. 1. With reference to FIG. 1 and FIG. 2, the refrigerator which concerns on this Embodiment is demonstrated.

  As shown in FIGS. 1 and 2, the refrigerator 1 according to the present embodiment includes a housing 10 including a main body 11 and an opening / closing door 12. The main body 11 includes a steel plate outer box, a synthetic resin inner box, and a heat insulating material filled therebetween. The inside of the main body 11 is partitioned into a refrigerator compartment 20 and a freezer compartment 23 by a partition wall 13.

  The refrigerator compartment 20 is divided into a refrigerator compartment 21 and a vegetable compartment 22 by the partition plate 14. A lower portion of the main body 11 is partitioned as a machine room 24.

  In the machine room 24, a compressor 41 and a condenser 42 are disposed. The refrigerator 1 includes, as a refrigeration cycle, a compressor 41, a condenser 42 for condensing the refrigerant compressed by the compressor 41, and a decompression device (not shown) for expanding the refrigerant condensed by the condenser 42. And a cooler 43 that evaporates the refrigerant that has passed through the decompression device and generates cold air by heat exchange with the surrounding air.

  When the compressor 41 is driven and the refrigeration cycle functions, the refrigerant compressed into a high-temperature and high-pressure state flows from the compressor 41 into the condenser 42 and is liquefied (condensed), and the liquefied refrigerant is decompressed through the decompression device. As a result, the temperature becomes low and flows into the cooler 43. After the refrigerant takes heat from the surroundings and vaporizes in the cooler 43, the refrigerant returns to the compressor 41. During the function of the refrigeration cycle, the cold air generated by the heat exchange of the cooler 43 circulates in the freezing room 23, the refrigerated storage room 21 and the vegetable room 22, and the temperatures of the freezing room 23, the refrigerated storage room 21 and the vegetable room 22 are increased. Maintained at a predetermined temperature.

  A cooler chamber 30 is provided on the back side of the freezer chamber 23. The storage space of the freezing chamber 23 and the cooler chamber 30 are partitioned by a cooler cover 38. In the cooler chamber 30, a cooler 43, a defrost heater 50 and a blower 60 are disposed.

  The cooler 43 cools the air taken into the cooler chamber 30 from the freezer compartment 23 and the air returning from the return port 39a to the cooler chamber 30 through a return duct 39 to be described later. The cooler 43 includes a refrigerant pipe extending in the vertical direction of the cooler chamber 30 while meandering.

  The blower 60 is provided above the cooler 43. In front of the blower 60 and in front of the cooler cover 38, a freezer compartment air passage 31 for sending cool air from the cooler compartment 30 to the freezer compartment 23 is provided.

  At the lower end of the air passage 31 for the freezer compartment, an air outlet 31a that blows out cool air into the freezer compartment 23 is provided. A damper 33 is provided so as to cover the outlet 31a from the freezer compartment 23 side. Below the cooler cover 38, a suction port 32 is provided for sucking cold air circulated in the freezer compartment 23 into the cooler chamber 30.

  On the upper side of the blower 60 and on the back side of the refrigerated storage room 21 and the vegetable room 22, a refrigeration room air passage 34 that connects the cooler room 30 and the refrigerated storage room 21 is provided. The air passage 34 for the refrigerator compartment is provided with an air outlet 35 that blows out cold air at a predetermined interval in the vertical direction. A damper 36 is provided in an intermediate region of the refrigeration chamber air passage 34 from the cooler chamber 30 to the refrigeration storage chamber 21.

  The defrost heater 50 is provided below the cooler 43. The defrost heater 50 defrosts the frost adhering to the cooler 43. The detailed configuration of the defrost heater 50 will be described later with reference to FIG.

(Flow of cold air)
When the inside of the freezer compartment 23 is cooled, the damper 36 is closed and the damper 33 is opened. Thereby, the cold air generated in the cooler 43 is blown out from the blower outlet 31a into the freezer compartment 23 through the freezer blower passage 31 by the blower 60. The cool air blown into the freezer compartment 23 cools the inside of the freezer compartment 23 to a predetermined temperature. The cold air that has cooled the inside of the freezing chamber 23 is sucked into the cooler chamber 30 through the suction port 32, and is cooled again by the cooler 43.

  The suction port 32 is an opening having a width substantially equal to the longitudinal direction of the cooler 43 (the left-right direction of the refrigerator 1). For this reason, the air A <b> 1 sucked from the suction port 32 is uniformly cooled over the entire width of the cooler 43.

  When the inside of the refrigerator compartment 20 is cooled, the damper 33 is closed and the damper 33 is opened. Thereby, the cold air generated by the cooler 43 is blown out from the blowout port 35 to the refrigerating storage chamber 21 through the refrigerating chamber air passage 34 by the blower 60. The cold air blown into the refrigerated storage room 21 cools the refrigerated storage room 21 to a predetermined temperature.

  The cold air circulated in the refrigerated storage chamber 21 faces the lower side of the refrigerated storage chamber 21 and is provided between the partition plate 14 located on the back side and the partition wall 13 located on the back side. Go into the vegetable compartment 22 through 37. The cold air that has entered the vegetable compartment 22 cools the vegetable compartment 22 to a temperature slightly higher than the temperature of the refrigerated storage compartment 21.

  A return duct 39 communicating with the cooler chamber 30 is provided at one end side in the left-right direction at the bottom rear portion of the vegetable chamber 22. A return port 39a, which is an open end below the return duct 39, is provided on the right side surface of the cooler 43 when viewed from the front. The return port 39a is located between the lower end of the cooler 43 and the bottom surface of the cooler chamber 30 in the vertical direction.

  The cold air that has cooled the vegetable chamber 22 returns to the cooler chamber 30 through the return duct 39 and is cooled in the cooler chamber 30. Thus, when returning the return air A2 of the vegetable compartment 22 from the side lower part of the cooler 43 to the cooler compartment 30, the amount of highly humid air increases in the vicinity of the return port 39a. For this reason, frost formation increases in the cooler 43 located in the vicinity of the return port 39a.

  The defrosting heater 50 according to the present embodiment has a configuration in which the amount of heat generated on the side with a larger amount of frost formation is set to be larger than the amount of heat generated on the side with a smaller amount of frost formation, as will be described later. can do.

(Defrost heater)
FIG. 3 is a schematic diagram of the defrost heater according to the present embodiment. With reference to FIG. 3, the defrost heater 50 which concerns on this Embodiment is demonstrated.

  As shown in FIG. 3, the defrosting heater 50 according to the present embodiment includes a glass tube 51, a sealing member 52, a heater wire 56, a lead wire 57, and a caulking portion 58 as a movement preventing portion.

  The glass tube 51 has a substantially cylindrical shape. The sealing member 52 seals both ends of the glass tube 51. The sealing member 52 is provided with an insertion hole through which the lead wire 57 can be inserted.

  The heater wire 56 is installed in the glass tube 51. The heater wires 56 have substantially the same wire diameter. The heater wire 56 is configured by a metal resistor wound in a coil shape. The metal resistor has a linear shape with substantially uniform rigidity in the length direction before winding.

  The metal resistor has a diameter of 0.26 to 0.35 mm, for example. The metal resistor is made of, for example, a Fe—Cr alloy or a Ni—Cr alloy.

  The heater wire 56 includes a narrow pitch portion 54 having a narrow winding interval, a wide pitch portion 53 having a winding interval wider than the narrow pitch portion 54, and a lead portion 55. The narrow pitch portion 54 and the wide pitch portion 53 are provided continuously. Thus, since the heater wire 56 can be manufactured only by winding one metal resistor with the pitch changed in the longitudinal direction, the heater wire 56 can have a simple configuration. The lead portion 55 is located on both ends of the heater wire 56 and is connected to the lead wire 57.

  The caulking portion 58 is provided at a boundary portion between the narrow pitch portion 54 and the wide pitch portion 53. The caulking portion 58 is a portion formed by caulking a caulking member constituted by a metal member or the like at a boundary portion between the narrow pitch portion 54 and the wide pitch portion 53. The caulking portion 58 is provided so as to intersect the axial direction of the glass tube 51. The caulking portion 58 is provided over the inner diameter of the glass tube, and is provided so as to contact the inner peripheral surface of the glass tube 51 facing each other.

  Thereby, when attaching the defrost heater 50, when the defrost heater 50 is inclined, a frictional force acts between the caulking portion 58 and the inner peripheral surface, and the narrow pitch portion 54 and the wide pitch portion 53 It is possible to prevent the boundary from moving in the axial direction of the glass tube 51.

  By preventing the movement of the boundary portion, the narrow pitch portion 54 is prevented from being displaced from a desired position, and the side where the frost amount increases in the cooler 30 is stabilized at a high temperature as will be described later. And can be heated.

  By energization from the lead wire 57, the narrow pitch portion 54 and the wide pitch portion 53 of the heater wire 56 generate heat. When this radiant heat is transferred to the cooler 43, the frost attached to the cooler 43 is defrosted.

  The amount of heat generated differs depending on the winding interval, and the amount of heat generated by the narrow pitch portion 54 is larger than the amount of heat generated by the wide pitch portion 53. The heater wire 56 includes a narrow pitch portion 54 on the side close to the return port 39a of the return duct 39 and includes a wide pitch portion 53 on the side far from the return port 39a. Specifically, the narrow pitch portion 54 is disposed on the return duct 39 on the side close to the return port 39a, and the wide pitch portion 53 is disposed on the side far from the return port 39a. Thereby, the temperature of the part side with much frost formation can be made high, and efficient defrosting can be performed.

(Embodiment 2)
(Defrost heater)
FIG. 4 is a schematic diagram of the defrost heater according to the present embodiment. With reference to FIG. 4, the defrost heater which concerns on this Embodiment is demonstrated.

  As shown in FIG. 4, when the defrost heater 50A according to the present embodiment is compared with the defrost heater 50 according to the first embodiment, a rib 51a in which a movement preventing portion is provided in the glass tube 51, It is different in that it is constituted by 51b. Other configurations are almost the same.

  The ribs 51a and 51b provided in the glass tube 51 are provided so as to protrude radially inward from the inner surface of the glass tube. The ribs 51a and 51b are provided so as to face each other. The ribs 51a and 51b are provided so as to be shifted in the axial direction. A boundary portion between the narrow pitch portion 54 and the wide pitch portion 53 is located between the ribs 51a and 51b.

  By providing the ribs 51a and 51b as described above, when the defrost heater 50A is inclined when the defrost heater 50A is attached, the end of the wide pitch portion 53 positioned on the narrow pitch portion 54 side is The end of the narrow pitch portion 54 that is in contact with the rib 51b or located on the wide pitch portion 53 side is in contact with the rib 51a. Thereby, it can prevent that the boundary of the narrow pitch part 54 and the wide pitch part 53 moves to the axial direction of the glass tube 51. FIG.

  Moreover, since the heater wire 56 can be manufactured only by winding one metal resistor with the pitch changed in the longitudinal direction, the heater wire 56 can have a simple configuration. Furthermore, the heat generation amount is adjusted according to the amount of frost formation by arranging the narrow pitch portion 54 on the side where the frost amount increases and the wide pitch portion 53 on the side where the frost amount decreases. be able to. As a result, efficient defrosting can be performed.

(Embodiment 3)
(Structure of the refrigerator)
FIG. 5 is a diagram illustrating movement of air in the refrigerator according to the present embodiment. With reference to FIG. 5, the refrigerator 1B which concerns on this Embodiment is demonstrated.

  As shown in FIG. 5, the cooler 1 </ b> B according to the present embodiment differs from the cooler 1 according to the first embodiment in the configuration of the return duct 39 </ b> B and the defrost heater 50 </ b> B. Other configurations are almost the same.

  The return duct 39 </ b> B provided in the cooler 1 </ b> B has a shape that bends in the left-right direction at the lower part of the cooler chamber 30. The return port 39a is disposed on one facing surface side of the cooler 43 positioned in the front-rear direction. Specifically, the return port 39 a of the return duct 39 </ b> B is disposed on the lower front side of the cooler 43. The return port 39a is provided so as to extend in the left-right direction.

  In such a configuration, the air A <b> 1 sucked from the suction port 32 is uniformly cooled over the entire width of the cooler 43 on the lower side of the cooler 43. Further, since almost the same amount of return air A3 is blown out from the return port 39a in the left-right direction toward the cooler 43, the air is cooled uniformly over the entire width of the cooler 43.

  Here, the defrost heater 50 </ b> B according to the present embodiment can be efficiently defrosted by being configured so that the heat generation amount is substantially uniform over the axial direction (left-right direction) of the glass tube 51. it can.

(Defrost heater)
FIG. 6 is a schematic diagram of the defrost heater according to the present embodiment. With reference to FIG. 6, the defrost heater 50B which concerns on this Embodiment is demonstrated.

  As shown in FIG. 6, the defrost heater 50B according to the present embodiment has a configuration of the heater wire 56B and a caulking portion 58 as a movement preventing portion when compared with the defrost heater 50 according to the first embodiment. The number is different. Other configurations are almost the same.

  The heater wire 56 </ b> B is configured by a narrow pitch portion 54 disposed on each end of the glass tube 51, and a wide pitch portion 53 disposed between the two narrow pitch portions 54.

  A caulking portion 58 is provided at a boundary portion between the narrow pitch portion 54 located on one end side of the glass tube 51 and the wide pitch portion 53 located on the center side of the glass tube 51. A caulking portion 58 is provided at a boundary portion between the narrow pitch portion 54 located on the other end side of the glass tube 51 and the wide pitch portion 53 located on the center side of the glass tube 51.

  By providing the caulking portion 58 in this manner, as described above, when the defrost heater 50B is inclined, a frictional force acts between the caulking portion 58 and the inner peripheral surface of the glass tube 51, and the narrow pitch portion It can prevent that the boundary of 54 and the wide pitch part 53 moves to the axial direction of the glass tube 51. FIG.

  Further, the heater wire 56B can be manufactured simply by winding a single metal resistor by changing the pitch in the longitudinal direction (the axial direction of the glass tube 51), and thus can have a simple configuration.

  FIG. 7 is a view showing a temperature distribution along the axial direction of the defrosting heater shown in FIG. With reference to FIG. 7, the temperature distribution along the axial direction (W direction in FIG. 7) of the defrosting heater 50B will be described. In FIG. 7, when the heater wire 56 is configured by providing only the wide pitch portion 53 along the axial direction of the glass tube 51, the temperature distribution is indicated by a broken line, and the heater wire 56 according to the present embodiment is employed. The temperature distribution is indicated by a solid line.

  As shown in FIG. 7, the temperature tends to be low at both ends of the glass tube 51, and the temperature tends to be high at the center of the glass tube 51.

  On the other hand, in the defrosting heater 50B according to the present embodiment, the narrow pitch portion 54 is disposed on each of both end sides of the glass tube 51, and the wide pitch portion 53 is disposed between the two narrow pitch portions 54. By adopting the configuration, the temperature at both ends of the glass tube 51 can be increased as compared with the case where the heater wire 56 is configured by providing only the wide pitch portion 53 in the axial direction of the glass tube 51. Thereby, the defrost heater 50B which concerns on this Embodiment can make temperature distribution uniform over the axial direction of the glass tube 51. FIG.

  As described above, when the suction port 32 and the return port 39a are provided in the left and right direction below the front surface of the cooler 43, the air sucked from the suction port 32 and blown out from the return port 39a. The return air is uniformly cooled by the cooler 43.

  For this reason, frost adheres uniformly to the cooler 43 in the left-right direction. Therefore, it can defrost efficiently by defrosting using the defrost heater 50B which has uniform temperature distribution over the axial direction of the glass tube 51 like this Embodiment.

  In Embodiment 1 mentioned above, although the case where the return port 39a was provided only in the right side surface of the cooler 43 was illustrated and demonstrated, it is not limited to this and may be provided only in the left side surface, It may be provided on both side surfaces. Even in such a case, by arranging the narrow pitch portion 54 on the side close to the return port, the temperature on the side where the amount of defrost is increased can be increased, and defrosting can be performed efficiently.

  In Embodiment 3 mentioned above, although the case where the return port 39a was provided in the lower front surface of the cooler 43 was illustrated and demonstrated, it is not limited to this and may be provided in the lower rear surface, or the lower front surface And may be provided both below the rear surface. Even in such a case, since the return cold air is uniformly cooled in the left-right direction by the cooler, by defrosting using the defrost heater 50B having a uniform temperature distribution over the axial direction of the glass tube 51, Defrosting can be performed efficiently.

  In Embodiment 1 to 3 mentioned above, although the case where a defrost heater had a caulking part or a rib as a movement prevention part was illustrated and demonstrated, it is not limited to this, A heater wire does not change substantially with dead weight. As long as it has rigidity, a crimp part or a rib is not essential. Further, instead of the caulking portion, a compression elastic member that applies a force radially outward in the glass tube may be used.

  When the heater wire has a rigidity that does not substantially deform due to its own weight, even when the defrost heater 50 is inclined when the defrost heater 50 is attached, the narrow pitch portion and the wide pitch of the defrost heater 50 It can prevent that the boundary part with a part moves. In addition, when a caulking part or a rib is provided as the movement preventing part, the movement of the boundary part can be prevented more reliably.

  Although the embodiments of the present invention have been described above, the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and includes meanings equivalent to the terms of the claims and all modifications within the scope.

  1, 1B refrigerator, 10 housing, 11 body, 12 door, 13 partition wall, 14 partition plate, 20 refrigerator compartment, 21 refrigerator compartment, 22 vegetable compartment, 23 freezer compartment, 24 machine compartment, 30 cooler compartment, 31 Ventilation path for freezer compartment, 31a Air outlet, 32 Suction port, 33 damper, 34 Air passage for refrigeration room, 35 Air outlet, 36 damper, 37 Cold air passage, 38 Cooler cover, 39, 39B Return duct, 39a Return port , 41 Compressor, 42 Condenser, 43 Cooler, 50, 50A, 50B Defrost heater, 51 Glass tube, 51a, 51b Rib, 52 Sealing member, 53 Wide pitch portion, 54 Narrow pitch portion, 55 Lead portion, 56, 56B Heater wire, 57 Lead wire, 58 Caulking portion, 60 Blower.

Claims (5)

A defrost heater that defrosts frost attached to a cooler that generates cold air,
A glass tube,
A sealing member for sealing both ends of the glass tube;
A heater wire made of a metal resistor installed in the glass tube and wound in a coil shape,
The heater wire has a wire diameter of approximately the same, and a narrow pitch portion of the winding gap, seen including a winding interval is wide wide pitch portion than the narrow pitch portion,
A movement preventing part for preventing the boundary between the narrow pitch part and the wide pitch part from moving in the axial direction of the glass tube is provided at the boundary part between the narrow pitch part and the wide pitch part. Frost heater. The defrost heater according to claim 1, wherein the movement preventing unit is provided so that a frictional force is applied in contact with an inner surface of the glass tube . The defrost heater according to claim 1, wherein the movement prevention unit is configured by a rib protruding in a radial direction from an inner surface of the glass tube.   The defrost according to any one of claims 1 to 3, wherein the narrow pitch portion is disposed on each of both ends of the glass tube, and the wide pitch portion is disposed between the two narrow pitch portions. heater. The defrost heater according to any one of claims 1 to 3 ,
A freezer compartment and a refrigerator compartment separated from the freezer compartment;
A cooling chamber provided on the back side of the freezing chamber;
A return duct for sending the air in the refrigerator compartment to the cooling chamber,
The cooler is disposed in the cooling chamber, cools the air taken into the cooling chamber from the freezing chamber and the air returning to the cooling chamber from a return port of the return duct, and while meandering, the cooling chamber A refrigerant pipe extending in the vertical direction of
The return port is disposed on at least one side surface of the cooler located in the left-right direction,
The heater wire includes the narrow pitch portion on a side closer to the return port, and includes the wide pitch portion on a side far from the return port.

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