Patent Description:
In some high-pressure heat exchangers, a connecting block and a heat exchange core body are arranged in a cavity of a housing after being integrally formed. An accommodating hole is provided in the housing, a part of the connecting block extends into the cavity after passing through the accommodating hole, another part is located outside the housing, and a sealing structure is provided between the connecting block and the accommodating hole to seal the cavity. In addition, in order to enable the heat exchange core body to be accommodated in the cavity, the housing can be divided into an upper portion and a lower portion, and a sealing structure needs to be further provided between the upper and lower portions.

An object according to the present application is to provide a heat as defined in claim <NUM>.

According to the present application, the heat exchanger includes the core body, the housing and the connecting block, the first cavity is formed in the housing, the connecting block is fixed to the hosing and the connecting block is arranged outside the first cavity, the core body is fixedly arranged in the first cavity, and the first flow-through hole is in communication with the multiple heat exchange pipes through the second flow-through hole, so as to enhance the connection strength and sealing between the core body and the housing.

Reference numerals in the drawings are as follows:.

Referring to <FIG> and <FIG>, a heat exchanger includes a housing, the housing includes a first body <NUM> and a second body <NUM>, the first body <NUM> is made of metal, the second body <NUM> is made of plastic, the first body <NUM> is in a flat-plate shape, and a second flow-through hole <NUM> is provided in the first body <NUM>.

Referring to <FIG> and <FIG>, the core body includes multiple heat exchange pipes <NUM> and a first collecting assembly <NUM>, second fluid passage are formed inside the multiple heat exchange pipes <NUM>, first fluid passages are formed between the multiple heat exchange pipes <NUM>, the first collecting assembly <NUM> is in communication with the multiple heat exchange pipes <NUM>, the first collecting assembly <NUM> includes a collecting pipe <NUM>, a flow-through plate <NUM> and a first connecting plate <NUM>, multiple first heat exchange pipe mounting grooves <NUM> are provided in the first connecting plate <NUM> along a length direction of the first connecting plate <NUM>, one end of the multiple heat exchange pipes <NUM> is arranged in the multiple first heat exchange pipe mounting grooves <NUM>, the collecting pipe <NUM> is arranged on a side of the first connecting plate <NUM> away from the multiple heat exchange pipes <NUM>, a throttling passage is provided on the collecting pipe <NUM> along an arrangement direction of the multiple first heat exchange pipe mounting grooves <NUM>, the flow-through plate <NUM> is arranged between the collecting pipe <NUM> and the first connecting plate <NUM>, and distribution passages <NUM> are provided in the flow-through plate <NUM> along the arrangement direction of the multiple first heat exchange pipe mounting grooves <NUM>, and the throttling passage is in communication with the multiple heat exchange pipes <NUM> through the distribution passages <NUM>.

Referring to <FIG> and <FIG>, the core body further includes a second collecting assembly <NUM>, the second collecting assembly <NUM> includes a second connecting plate <NUM>, a baffle plate <NUM> and an enclosure plate <NUM>, multiple second heat exchange pipe mounting grooves <NUM> are provided in the second connecting plate <NUM> along a length direction of the second connecting plate <NUM>, another ends of the multiple heat exchange pipes <NUM> are arranged in the multiple second heat exchange pipe mounting grooves <NUM>, the enclosure plate <NUM> is arranged on a side of the second connecting plate <NUM> away from the multiple heat exchange pipes <NUM>, the baffle plate <NUM> is arranged between the enclosure plate <NUM> and the second connecting plate <NUM>, baffle passages <NUM> in communication with the multiple second heat exchange pipe mounting grooves <NUM> are provided in the baffle plate <NUM> along an arrangement direction of the multiple second heat exchange pipe mounting grooves <NUM>. As shown in <FIG>, the baffle passages <NUM> are in a long-strip shape, two columns of the heat exchange pipes <NUM> are in communication by the second connecting plate <NUM> to form a U-shaped circuit. By forming the U-shaped circuit, the heat exchange efficiency of the heat exchanger is improved.

Referring to <FIG>, two collecting pipes <NUM> are provided, which are arranged side by side on one side of the multiple heat exchange pipes <NUM>. As shown in <FIG>, specifically, the two collecting pipes <NUM> are arranged on a same plate body and can be integrally formed on the plate body, one collecting pipe <NUM> is used as a passage for the fluid flowing in the multiple heat exchange pipes <NUM>, the other collecting pipe <NUM> is used as a passage for the fluid flowing out through the multiple heat exchange pipes <NUM>, the throttling passages and the multiple first heat exchange pipe mounting grooves <NUM> are arranged in two columns, the distribution passages <NUM> are provided in the flow-through plate <NUM> along the arrangement direction of the multiple first heat exchange pipe mounting grooves <NUM>, the distribution passages <NUM> are arranged in two columns, each distribution passage <NUM> corresponds to one first heat exchange pipe mounting groove <NUM>, and each distribution passage <NUM> corresponds to one throttling passage, which increases the uniformity of fluid distribution and improves the heat exchange effect. As shown in <FIG>, two sides of the second connecting plate <NUM> both include a hemming part <NUM>, and the hemming parts <NUM> can be L-shaped as shown in <FIG>, so that U-shaped clamp slots are formed at positions where the hemming parts <NUM> are. During mounting, two sides of the flow-through plate <NUM> and two sides of the plate body provided with the collecting pipes <NUM> can be press-fitted in the hemming parts <NUM>, that is, clamped and pressed in the clamp slots formed by the hemming parts <NUM>, so as to improve the reliability of mounting and save space.

The core body further includes a second collecting assembly <NUM>, the second collecting assembly <NUM> includes a second connecting plate <NUM>, a baffle plate <NUM> and an enclosure plate <NUM>, multiple second heat exchange pipe mounting grooves <NUM> are provided on the second connecting plate <NUM> along a length direction of the second connecting plate <NUM>, the multiple second heat exchange pipe mounting grooves <NUM> are arranged in two columns, another end of the multiple heat exchange pipes is arranged in the multiple second heat exchange pipe mounting grooves <NUM>, the enclosure plate <NUM> is arranged on a side of the second connecting plate <NUM> away from the multiple heat exchange pipes <NUM>, the baffle plate <NUM> is arranged between the enclosure plate <NUM> and the second connecting plate <NUM>, baffle passages <NUM> in communication with the multiple second heat exchange pipe mounting grooves <NUM> are provided in the baffle plate <NUM> along an arrangement direction of the multiple second heat exchange pipe mounting grooves <NUM>, and the baffle passages <NUM> are arranged in a column to form a rows-in-series structure. Each baffle passage <NUM> corresponds to two second heat exchange pipe mounting grooves in a same row of the two columns, which saves the spaced occupied by the core body, thus greatly reduces the volume of the heat exchanger under the premise of satisfying the heat exchange efficiency. As shown in <FIG>, two sides of the second connecting plate <NUM> both include a hemming part <NUM>, and the hemming parts <NUM> can be L-shaped as shown in <FIG>, so that U-shaped clamp slots are formed at positions where the hemming parts <NUM> are. During mounting, two sides of the enclosure plate <NUM> and two sides of the baffle plate <NUM> are press-fitted in the hemming parts <NUM>, that is, clamped and pressed in the clamp slots formed by the hemming parts <NUM>, so as to improve the reliability of mounting and save space.

Alternatively, the second collecting assembly <NUM> can be arranged in a same structure with the first collecting assembly <NUM>, that is, the two first collecting assemblies <NUM> are arranged at two ends of the multiple heat exchange pipes <NUM>, respectively.

Alternatively, each distribution passage <NUM> can correspond to multiple first heat exchange pipe mounting grooves <NUM> in a same column, and each distribution passage <NUM> can correspond to multiple throttling passages. The specific corresponding relationship can be set according to specific requirements, which will not be described here.

Referring to <FIG>, the core body is fixedly arranged on one side of the first body <NUM>, the side of the first body <NUM> in contact with the core body is provided with a solder composite layer, or a side of the core body in contact with the first body <NUM> is provided with a solder composite layer, or the side of the first body <NUM> in contact with the core body and the side of the core body in contact with the first body <NUM> are both provided with a solder composite layer. Taking the case that the side of the first body <NUM> in contact with the core body being provided with the solder composite layer as an example, the core body is welded to the first body <NUM> by the solder composite layer, which enhances the strength of the heat exchanger and the reliability of the heat exchanger. The second flow-through hole <NUM> is in communication with the second fluid passages through the collecting pipe <NUM>. Furthermore, a protruding portion <NUM> extending along a circumferential direction of the second flow-through hole <NUM> toward a side where the core body is located is provided at the second flow-through hole <NUM>, and the protruding portion <NUM> extends into the collecting pipe <NUM> through an opening of the collecting pipe <NUM>. The protruding portion <NUM> can facilitate the positioning of the core body, and reduce the risk of deviation of the core body relative to the first body <NUM>, and facilitate the assembly of the core body with the first body <NUM>. Furthermore, an outer wall of the protruding portion <NUM> in contact with the collecting pipe <NUM> is provided with a solder composite layer, the protruding portion <NUM> can be welded to an inner side wall of the collecting pipe <NUM> by the solder composite layer arranged on the outer wall of the protruding portion <NUM>, which improves the welding strength between the core body and the first body <NUM>. In addition, since the protruding portion <NUM> is welded to the collecting pipe <NUM>, it improves the sealing performance between the second flow-through hole <NUM> and the collecting pipe <NUM>, prevents medium flowing through the second flow-through hole <NUM> from leaking into the first fluid passages between the multiple heat exchange pipes <NUM> during the process of flowing into the second fluid passages in the heat exchange pipes <NUM>, which further improves the heat exchange effect of the heat exchanger.

Referring to <FIG>, the heat exchanger further includes a connecting block <NUM>, which is fixedly arranged on a side of the first body <NUM> away from the core body, a first flow-through hole <NUM> is provided in the connecting block <NUM> along a thickness direction of the connecting block <NUM>, and a second flow-through hole <NUM> is in communication with the second fluid passages through the first flow-through hole <NUM>, that is, the first flow-through hole <NUM>, the second flow-through hole <NUM> and the second fluid passages are in communication in sequence. A side of the first body <NUM> in contact with the connecting block <NUM> is provided with a solder composite layer, or a side of the connecting block <NUM> in contact with the first body <NUM> is provided with a solder composite layer, or the side of the first body <NUM> in contact with the connecting block <NUM> and the side of the connecting block <NUM> in contact with the first body <NUM> are both provided with a solder composite layer. Taking the case that the side of the connecting block <NUM> in contact with the first body <NUM> is provided with the solder composite layer as an example, the connecting block <NUM> is welded to the first body <NUM> by the solder composite layer, which enhances the connection strength between the connecting block <NUM> and the first body <NUM>, improves the sealing between the first flow-through hole <NUM> and the second flow-through hole <NUM>, and reduces the risk of heat exchange leakage. In addition, since the connecting block <NUM> and the core body are arranged on two sides of the first body <NUM>, respectively, it is not necessary to provide an accommodating hole for accommodating the connecting block <NUM> in the first body <NUM>, so that the core body does not need to be connected in the first body <NUM> by the connecting block <NUM> being accommodated in the accommodating hole, which reduces the risk of the relative movement between the core body and the first body <NUM> caused by frequent vibration. In addition, since the second flow-through hole <NUM> with a small diameter is provided in the first body <NUM>, it is not necessary to provide an accommodating hole with a large diameter for accommodating the connecting block <NUM>, which greatly reduces the difficulty of sealing and effectively reduces the risk of leakage of the heat exchanger.

Referring to <FIG>, the second body <NUM> has a U-shaped tank portion <NUM>, the U-shaped herein means that a cross section is substantially U-shaped, and the second body <NUM> is made of plastic, to reduce the weight of the heat exchanger. The second body <NUM> includes a bottom plate <NUM> and side plates <NUM>. The number of side plates <NUM> is four, the four side plates <NUM> are sealingly connected end to end in sequence, and the four side plates <NUM> are arranged substantially vertically on the bottom plate <NUM>, and portions of the four side plates <NUM> in contact with the bottom plate <NUM> are sealed, the tank portion <NUM> is formed by enclosure of the bottom plate <NUM> and the four side plates <NUM>, one of the four side plates <NUM> is configured in an arc shape, a second abutment portion <NUM> is provided at the top of the four side plates <NUM>, a first abutment portion <NUM> is provided on an outer circumference of the first body <NUM>, and the first abutment portion <NUM> is bonded with the second abutment portion <NUM> with glue, so that the first body <NUM> is connected to the second body <NUM> to form the first cavity. The core body is arranged in the first cavity, and the collecting pipe <NUM> is arranged close to the arc side plate <NUM>. Alternatively, the number of the side plates <NUM> may be any, which can be arranged according to needs. Furthermore, the first abutment portion <NUM> is integrally formed with the first body <NUM>, that is, the first abutment portion <NUM> is an outer circumferential portion of the first body <NUM>.

Referring to <FIG>, the arc portions <NUM> are provided on two side plates <NUM> connected to the arc side plate <NUM>, respectively, a first duct is formed between the arc portions <NUM> and the core body, a second hole <NUM> in communication with the first duct is provided in the first body <NUM>, and two sides of the first body <NUM> protrude outward to form arc portions of the second hole <NUM> which correspond to the arc portions <NUM> on the two side plates <NUM>. The core body includes multiple heat exchange pipes <NUM>, first fluid passages are formed between the multiple heat exchange pipes <NUM>, the second hole <NUM> is in communication with the first fluid passages through the first duct, that is, the second hole <NUM>, the first duct and the first fluid passages are in communication in sequence. The heat exchanger further includes an external connecting pipe <NUM>, and one end of the external connecting pipe <NUM> is sealingly connected to the second hole <NUM>. The arc portions <NUM> provided herein are mainly configured to form the first duct with the core body, so as to be in communicating with the first fluid passages. The side plates <NUM> may be just arranged protruding outward, which is not limited to be in arc portion <NUM>. As an example, a refrigerant can be flow through the second fluid passages in the heat exchange pipes <NUM>, and various heat exchange fluids, such as water, can be flow through the first fluid passages outside the multiple heat exchange pipes <NUM>.

Furthermore, referring to <FIG>, a clamping edge <NUM>, which extends along a circumferential direction of the second abutment portion <NUM> toward a direction where the first body <NUM> is located, is provided on the second abutment portion <NUM>, the clamping edge <NUM> is continuously arranged along an open end of the second body <NUM>, and a side wall of the first abutment portion <NUM> abuts against the clamping edge <NUM>. During the assembly of the first body <NUM> and the second body <NUM>, the first abutment portion <NUM> can be moved along the clamping edge <NUM> in a direction close to the second abutment portion <NUM> until the first abutment portion <NUM> abuts against the second abutment portion <NUM>, which facilitates of the mounting and alignment of the first body <NUM> and the second body <NUM>. In addition, the arrangement of the clamping edge <NUM> reduces the possibility of glue overflow.

Referring to <FIG>, reinforcing ribs <NUM> are provided outside the second body <NUM>, so as to further improve the impact resistance of the heat exchanger and improve the service life of the heat exchanger. The reinforcing ribs <NUM> are arranged in a bar-shape. The number of the reinforcing ribs <NUM> is plural.

The structure and principle of the second embodiment is substantially the same with the first embodiment, and the difference is in that: the first body <NUM> is connected to the second body by a buckle, that is, a buckle portion <NUM> is provided on the first abutment portion <NUM>, and the first abutment portion <NUM> is pressed against and fixed to the second abutment portion <NUM> by the buckle portion <NUM>.

Referring to <FIG>, the buckle portion <NUM> is provided on the first abutment portion <NUM> along a circumferential direction of the first abutment portion <NUM>, the number of the buckle portion <NUM> is plural, and each buckle portion <NUM> protrudes from the first abutment portion <NUM> along a direction where the second abutment portion <NUM> is located. After the first abutment portion <NUM> is aligned with the second abutment portion <NUM>, the end of the buckle portions <NUM> away from the first abutment portion <NUM> is bent inward and presses against a lower surface of the second abutment portion <NUM>, so that the first abutment portion <NUM> is pressed against and fixed to the second abutment portion <NUM>. The buckle portion <NUM> is provided with a straight portion <NUM> and a blocking portion <NUM> by bending, and the straight portion <NUM> is perpendicular to the blocking portion <NUM>. It should be noted here that "perpendicular" does not means perpendicular in a complete mathematical sense, but also includes substantially perpendicular or having a perpendicular tendency. The straight portion <NUM> abuts against a side wall of the second abutment portion <NUM>, and the blocking portion <NUM> abuts against the lower surface of the second abutment portion <NUM>, so that the first abutment portion <NUM> is pressed against and fixed to the second abutment portion <NUM>. The first body <NUM> is detachably connected to the second body <NUM>, which facilitates the later cleaning and maintenance of the heat exchanger.

Furthermore, a sealing gasket or a sealing ring is provide between the first abutment portion <NUM> and the second abutment portion <NUM>, which improves the sealing of the heat exchanger. Furthermore, a sealing groove for accommodating the sealing gasket or the sealing ring is provided in one of the first abutment portion <NUM> and the second abutment portion <NUM>, which facilitates of the sealing between the first abutment portion <NUM> and the second abutment portion <NUM>, or the sealing grooves for accommodating the sealing gasket or the sealing ring are both provided in the first abutment portion <NUM> and the second abutment portion <NUM>, the sealing groove in the first abutment portion <NUM> is staggered with the sealing groove in the second abutment portion <NUM>, for example, after the first abutment portion <NUM> is aligned with and pressed against the second abutment portion <NUM>, the sealing groove in the first abutment portion <NUM> is located in an inner ring of the sealing groove in the second abutment portion <NUM>, so as to form a multi-stage seal, thereby improving the sealing of the heat exchanger.

The structure and principle of the third embodiment is substantially the same with the second embodiment, and the difference is in that: a clamping edge <NUM>, which extends along the circumferential direction of the first abutment portion <NUM> toward the direction where the second body <NUM> is located, is provided on the first abutment portion <NUM>, and the buckle portion <NUM> is in a straight-line shape.

Referring to <FIG>, a clamping edge <NUM>, which extends along the circumferential direction of the first abutment portion <NUM> toward the direction where the second body <NUM> is located, is provided on the first abutment portion <NUM>, a side wall of the second abutment portion <NUM> abuts against the clamping edge <NUM>, and one end of the buckle portion <NUM> is connected to a free end of the clamping edge <NUM>. After the first abutment portion <NUM> is aligned with the second abutment portion <NUM> and a connection between the buckle portion <NUM> and the clamping edge <NUM> is bent, the buckle portion <NUM> presses against the lower surface of the second abutment portion <NUM>, so that the first abutment portion <NUM> is pressed against and fixed to the second abutment portion <NUM>. By providing the clamping edge <NUM>, the strength of the first body <NUM> is improved.

The structure and principle of the fourth embodiment is substantially the same with the third embodiment, and the difference is in that: the first body <NUM> includes a U-shaped clamp slot <NUM>, the second abutment portion <NUM> is accommodated in the clamp slot <NUM>, and one end of the buckle portion <NUM> is connected to a free end of the clamp slot <NUM>.

Referring to <FIG>, the first body <NUM> is in a flat-plate shape, the second body <NUM> has a U-shaped tank portion <NUM>, an open end of the tank portion <NUM> extends outward to form a second abutment portion <NUM>, and the first body <NUM> includes the U-shaped clamp slot <NUM> and a first body portion <NUM>. The first body portion <NUM> is provided with a first extending portion <NUM>, which extends along a circumferential direction of the first body portion <NUM> in a direction away from the first cavity. A second extending portion <NUM>, which extends outward along a circumferential direction of the first extending portion <NUM>, is provided on the first extending portion <NUM>, and a third extending portion <NUM>, which extends along a circumferential direction of the second extending portion <NUM> toward the direction where the first cavity is located, is provided on the second extending portion <NUM>. The first extending portion <NUM>, the second extending portion <NUM> and the third extending portion <NUM> jointly form the clamp slot <NUM>, the second abutment portion <NUM> is accommodated in the clamp slot <NUM>, that is, two side walls of the second abutment portion <NUM> abut against the first extending portion <NUM> and a third extending portion, respectively, a top wall of the second abutment portion <NUM> abuts against the second extending portion <NUM>, one end of the buckle portion <NUM> is connected to an end of the third extending portion <NUM> away from the second extending portion <NUM>, the number of the buckle portions <NUM> is plural, and these buckle portions <NUM> are arranged along a circumferential direction of the third extending portion <NUM>. After connections between the buckle portions <NUM> and the third extending portion <NUM> are bent, the buckle portions <NUM> press against the lower surface of the second abutment portion <NUM> so that the second abutment portion <NUM> is pressed against and fixed to the third extending portion <NUM>, that is, the buckle portions <NUM> abut against the second abutment portion <NUM> so that the second abutment portion <NUM> is pressed against and fixed in the clamp slot <NUM>. By providing clamp slot <NUM>, the assembly of the first body <NUM> and the second body <NUM> is facilitated.

The structure and principle of the fifth embodiment is substantially the same with the first embodiment, and the difference is in that: a buckle portion <NUM> is provided on the second body <NUM>, and the buckle portion <NUM> buckles the first abutment portion <NUM> and the second abutment portion <NUM>.

Referring to <FIG>, the second body <NUM> further includes the buckle portion <NUM>, the buckle portion <NUM> is arranged along a circumferential direction of the second abutment portion <NUM>, the buckle portion <NUM> includes a straight portion <NUM> and a blocking portion <NUM>, one end of the straight portion <NUM> is connected to the second body <NUM>, the blocking portion <NUM>, which extends toward a direction where the first cavity is located, is provided at the other end of the straight portion <NUM>, a side wall of the blocking portion <NUM> is inclined, and the first body <NUM> is placed on the inclined side wall. By applying pressure to the first body <NUM>, the first body <NUM> is moved toward the direction where the first cavity is located. Since the buckle portion <NUM> is made of plastic, the straight portion <NUM> can be bent outward under pressing by the first body <NUM>, and the straight portion <NUM> returns to its original state due to its own resilience when the first abutment portion <NUM> is in contact with the second abutment portion <NUM>. At this time, a lower surface of the blocking portion <NUM> is in contact with and presses against an upper surface of the first abutment portion <NUM>, so that the first abutment portion <NUM> is pressed against and fixed to the second abutment portion <NUM>.

Besides, the first body <NUM> includes a U-shaped tank portion <NUM>, and the second body <NUM> also includes a U-shaped tank portion <NUM>, an open end of the tank portion <NUM> of the first body <NUM> is opposite to an open end of the tank portion <NUM> of the second body <NUM> and the first body <NUM> is connected to the second body <NUM>, and the connection location is sealed. Alternatively, the first body <NUM> has a U-shaped tank portion <NUM> and the second body <NUM> is in a flat-plate shape, and the second body <NUM> covers the tank portion <NUM> of the first body <NUM> at the open end thereof and it is also feasible for the connection location to be sealed. The structure and the principle of this embodiment are substantially the same with the above embodiments, which will not be described here.

An assembly method for a heat exchanger is provided according to the present application, the method is applicable to the above heat exchanger, and steps are as follows:.

The core body and the connecting block <NUM> are both welded to the first body so as to form an integral whole after welding, which is then directly assembled with the second body <NUM>, which saves the assembly process and saves cost.

Claim 1:
A heat exchanger, comprising a housing and a core body accommodated in the housing, wherein the housing comprises a first body (<NUM>) and a second body (<NUM>), the first body (<NUM>) is made of metal, the second body (<NUM>) is made of plastic, and the first body (<NUM>) and the second body (<NUM>) are connected to form a first cavity;
the core body is accommodated in the first cavity, the core body is fixedly connected to the first body (<NUM>), the core body comprises a plurality of heat exchange pipes (<NUM>), the plurality of heat exchange pipes (<NUM>) are stacked, a first fluid passage is formed between the plurality of heat exchange pipes (<NUM>), a second fluid passage is formed inside the plurality of heat exchange pipes (<NUM>), and the first fluid passage is not in communication with the second fluid passage;
the heat exchanger further comprises a connecting block (<NUM>), the connecting block (<NUM>) is fixed to the first body (<NUM>) and the connecting block (<NUM>) is located outside the first cavity, a first flow-through hole (<NUM>) is provided in the connecting block (<NUM>), a second flow-through hole (<NUM>) is provided in the first body (<NUM>), and the first flow-through hole (<NUM>) and the second fluid passage are in communication by the second flow-through hole (<NUM>);
wherein the first body (<NUM>) is in a flat-plate shape, the second body (<NUM>) has a U-shaped tank portion (<NUM>), the first body covers at an open end of the tank portion (<NUM>) of the second body (<NUM>) and a connection between the first body (<NUM>) and the second body (<NUM>) is sealed;
characterized in that
an arc portion protruding outward is provided on a side plate of the second body (<NUM>), a first duct is formed between the arc portion and the core body, and a second hole (<NUM>) in communication with the first duct is provided on the first body (<NUM>), wherein the second hole (<NUM>) is in communication with the first fluid passage through the first duct.