Two-position three-way electromagnetic valve

Abstract

The two-position three-way electromagnetic valve comprises a valve body, a valve seat, a valve element assembly and a pilot structure, the valve body and the valve seat are fixedly connected with each other and define a valve cavity, the valve element assembly is contained in the valve cavity and comprises a valve element, and the valve cavity is divided by the valve element to form a pilot cavity and a main valve cavity; the pilot structure comprises a fixed iron core, a movable iron core, an electromagnetic coil and an ejector rod, and the fixed iron core can enable the movable iron core to move in the first direction by means of a magnetic field induced by the electromagnetic coil; the ejector rod is fixedly connected to the movable iron core and partially extends into the pilot cavity, so that when the ejector rod moves in the first direction in response to movement of the movable iron core, the valve element is allowed to move in the valve cavity in the first direction, and therefore connection and disconnection of the first flow channel and the second flow channel are controlled. According to the two-position three-way electromagnetic valve, the pilot structure controls high-pressure gas flowing through the pilot port to drive the valve element, so that the response time is short, and the two-position three-way electromagnetic valve is suitable for working conditions with large gas pressure and large flow channel area.

Description

Technical Field

[0001] The utility model relates to the technical field of solenoid valves, in particular to a two-position three-way solenoid valve. Background Art

[0002] Generally speaking, a two-position three-way valve usually uses the movement of the valve core to achieve the switching of the flow channel inside the valve body. Specifically, there are two different flow channels in the valve body. When one of the two flow channels is closed, the other flow channel will be opened, and the movement of the valve core can achieve the switching between the two different flow channels.

[0003] However, current two-position, three-way valves typically use a motor to drive the valve core, as described in patent document KR102004855B1. These valves are often complex and expensive. Furthermore, when the flow path area and gas pressure are large, the motor's driving force is insufficient to move the valve core, resulting in the valve not functioning properly. Furthermore, motor-driven two-position, three-way valves have a slow response speed, making them unsuitable for use in brake systems. Utility Model Content

[0004] In order to overcome the above problems, the utility model provides a two-position three-way solenoid valve.

[0005] According to the utility model, a two-position three-way solenoid valve includes a valve body, a valve seat, a valve core assembly and a pilot structure, the valve body and the valve seat are fixedly connected to each other and enclose a valve cavity, the valve core assembly is accommodated in the valve cavity, the valve core assembly includes a valve core that can move in the valve cavity along a first direction, the valve cavity is divided by the valve core to form a pilot cavity and a main valve cavity, the valve core defines a first flow channel and a second flow channel in the main valve cavity; the pilot structure is connected to the side of the valve body away from the valve seat, the pilot structure includes a fixed iron core, a movable iron core, an electromagnetic coil and a push rod, the fixed iron core is configured to move the movable iron core along the first direction by means of a magnetic field induced by the electromagnetic coil; one end of the push rod in the first direction is fixedly connected to the movable iron core, and the other end extends into the pilot cavity and is movably connected to the valve core, so that when the push rod moves in the first direction in response to the movement of the movable iron core, the valve core is allowed to move in the valve cavity along the first direction, thereby controlling the on and off of the first flow channel and the second flow channel.

[0006] In a preferred embodiment of the present invention, a pilot port is provided on the valve body, and the pilot port penetrates the valve body along the first direction. The push rod is movably inserted into the pilot cavity through the pilot port.

[0007] In a preferred embodiment of the present invention, a pilot valve is provided at the other end of the push rod extending into the pilot cavity. The diameter of the pilot valve is larger than the diameter of the pilot port, and the pilot valve comprises an elastic material.

[0008] In a preferred embodiment of the present invention, an air inlet is provided on the valve body, and the air inlet is connected to the pilot port through a third flow channel, and the third flow channel is at least partially formed between the fixed iron core and the valve body; and an exhaust port is provided on the valve core, and the exhaust port passes through the valve core along the first direction, and a discharge port connected to the external environment is formed on the valve seat, and the pilot chamber can be connected to the exhaust port through the exhaust port.

[0009] In a preferred embodiment of the present invention, the pilot structure further includes a pilot spring, which is sandwiched between the fixed iron core and the movable iron core and is used to reset the movable iron core after the electromagnetic coil is powered off.

[0010] In a preferred embodiment of the present invention, the fixed iron core is arranged between the movable iron core and the valve body along the first direction, a concave cavity is formed on the fixed iron core, a protrusion that can be inserted into the concave cavity is formed on the movable iron core, and the push rod extends through the concave cavity to be fixedly connected to the movable iron core.

[0011] In a preferred embodiment of the present invention, the pilot structure also includes a shell and a metal plate, wherein the shell is generally hollow cylindrical, the metal plate is arranged on a side of the shell close to the valve body, and together with the shell forms an electromagnetic circuit acting on the electromagnetic coil, and the shell and the metal plate are both made of magnetic conductive material.

[0012] In a preferred embodiment of the present invention, the valve core assembly further includes a main spring, which is sandwiched between the valve core and the valve seat and is used to reset the valve core.

[0013] In a preferred embodiment of the present invention, the valve core assembly also includes a main valve, which is arranged at one end of the valve core away from the pilot chamber and is configured to open or close the first flow channel and the second flow channel in response to movement of the valve core along the first direction.

[0014] Therefore, the two-position, three-way solenoid valve of the present invention uses a pilot structure to control the high-pressure gas flowing through the pilot port to drive the valve core. This results in a shorter response time and is suitable for operating conditions with high gas pressures and large flow passage areas. Furthermore, compared to designs where the valve core is driven by a motor, the two-position, three-way solenoid valve of the present invention, which utilizes a pilot structure, is more cost-effective and simpler in structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following further describes the embodiments of the present invention in conjunction with the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or corresponding elements.

[0016] Figure 1 A schematic cross-sectional view of a two-position three-way solenoid valve in a closed state according to an embodiment of the present utility model is shown;

[0017] Figure 2 A schematic cross-sectional view shows a two-position three-way solenoid valve in an open state according to an embodiment of the present utility model. DETAILED DESCRIPTION

[0018] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and examples, wherein the same or similar components in the drawings are indicated by the same reference numerals. The detailed description of the following embodiments and the accompanying drawings are intended to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention. That is, the present invention is not limited to the described embodiments.

[0019] In the following description of the present invention, it should be noted that, unless otherwise specified, terms such as "upper," "lower," "inner," "outer," "top," and "bottom" indicating directions or positional relationships are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. The directional terms used in the following description refer to directions shown in the drawings and do not limit the specific structure of the present invention.

[0020] It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0021] In order to better understand the present invention, Figure 1 and Figure 2 The two-position three-way solenoid valve according to the embodiment of the present utility model is described, wherein: Figure 1 A schematic cross-sectional view of a two-position three-way solenoid valve in a closed state according to an embodiment of the present utility model is shown; Figure 2 A schematic cross-sectional view of a two-position three-way solenoid valve in an open state according to an embodiment of the present invention is shown. In the following description, the first direction refers to the axial direction of the two-position three-way solenoid valve, corresponding to Figure 1 and Figure 2The up and down directions in the second direction refer to the radial direction of the two-position three-way solenoid valve, corresponding to Figure 1 and Figure 2 The left and right directions in . Figure 1 and Figure 2 As shown, the two-position three-way solenoid valve includes a valve body 1, a valve seat 2, a valve core assembly 3 and a pilot structure 4.

[0022] The valve seat 2 is arranged on one side of the valve body 1 along a first direction and can be fixedly connected to the valve body 1 by means of a threaded connection or a press fit, thereby enclosing the valve body 1 and the valve seat 2 to form a valve cavity. The valve seat 2 is formed with a discharge port 21 that extends through the valve seat 2 along the first direction, thereby communicating with the valve cavity. The valve body 1 is formed with a first opening 11 and a second opening 12. The first opening 11 and the second opening 12 are arranged at different positions on the valve body 1 along the first direction, and both the first opening 11 and the second opening 12 extend through the valve body 1 in a second direction perpendicular to the first direction, thereby communicating with the valve cavity.

[0023] The valve core assembly 3 is accommodated in the valve cavity and includes a valve core 31, a main valve 32 and a main spring 33. The valve core 31 is capable of moving in a first direction in the valve cavity under the drive of the pilot structure 4. The valve core 31 includes a large diameter portion and a small diameter portion, wherein the outer diameter of the small diameter portion is smaller than the outer diameter of the large diameter portion. The outer peripheral surface of the large diameter portion of the valve core 31 is sealed against the inner peripheral surface of the valve cavity, and the valve cavity is divided into a pilot cavity C1 and a main valve cavity C2, wherein the pilot cavity C1 is located on the upper side of the large diameter portion, and the main valve cavity C2 is located on the lower side of the large diameter portion. A first flow channel p1 and a second flow channel p2 are formed in the main valve cavity C2, wherein the first opening 11 can be connected to the second opening 12 through the first flow channel p1, and the second opening 12 can be connected to the discharge port 21 through the second flow channel p2.

[0024] The main valve 32 is disposed at the end of the valve core 31 away from the pilot chamber C1. The outer diameter of the main valve 32 is larger than the outer diameter of the small diameter portion and larger than the diameter of the inner circumference of the main valve chamber C2. The main valve 32 can control the opening and closing of the first flow channel p1 and the second flow channel p2 in response to the up and down movement of the valve core 31. Specifically, when the valve core 31 drives the main valve 32 to move upward, the main valve 32 will close the first flow channel p1 and open the second flow channel p2, thereby allowing the fluid to flow between the second opening 12 and the discharge port 21 but not between the first opening 11 and the second opening 12, as shown in FIG. Figure 1 When the valve core 31 drives the main valve 32 to move downward, the main valve 32 will open the first flow channel p1 and close the second flow channel p2, whereby the fluid can flow between the first opening 11 and the second opening 12 but cannot flow between the second opening 12 and the discharge port 21, as shown Figure 2 shown.

[0025] The main spring 33 is interposed between the valve core 31 and the valve seat 2. For example, a hollow hole extending in a first direction is formed in the valve core 31. The main spring 33 is accommodated in the hollow hole. The main spring 33 is configured so that after the force exerted on the valve core 31 by the pilot structure 4 disappears, the valve core 31 is reset due to the elastic restoring force of the main spring, overcoming its own weight. This puts the solenoid valve into a non-operating state.

[0026] The pilot structure 4 is connected to a side of the valve body 1 away from the valve seat 2 along a first direction and is configured to move the valve core 31 in the valve cavity along the first direction, thereby controlling the opening and closing of the first flow passage p1 and the second flow passage p2.

[0027] like Figure 1 and Figure 2 As shown, the pilot structure 4 includes a sleeve 41, a fixed iron core 42, a movable iron core 43, a pilot spring 44, an electromagnetic coil 45, and a push rod 46. The sleeve 41 generally has a hollow shape with one end closed and the other end open, thereby forming a hollow cavity. The open end of the sleeve 41 faces the valve body 1. The fixed iron core 42 is disposed between the movable iron core 43 and the valve body 1 along a first direction. Specifically, the fixed iron core 42 is partially inserted into the open end of the sleeve 41 and closes the hollow cavity within the sleeve 41. The movable iron core 43 is accommodated in the hollow cavity of the sleeve 41 and is movable relative to the fixed iron core 42 in the first direction within the hollow cavity. The electromagnetic coil 45 is disposed around the outer circumference of the sleeve 41.

[0028] A pilot spring 44 is disposed between the fixed iron core 42 and the movable iron core 43 and is configured to reset the movable iron core 43. Specifically, the pilot spring 44 is housed in the hollow bore of the fixed iron core 42, with one end of the pilot spring abutting against the fixed iron core 42 and the other end abutting against the movable iron core 43. The upper end of the push rod 46 in the first direction is fixedly connected to the movable iron core 43 and can thus move along with the movable iron core 43 in the first direction. The lower end of the push rod 46 in the first direction extends into the pilot chamber C1 and is movably connected to the valve core 31.

[0029] Illustratively, the pilot structure 4 further includes a housing 48 and a metal plate 49. The housing 48 is generally hollow and cylindrical, at least partially housing the sleeve 41, the fixed iron core 42, the movable iron core 43, the pilot spring 44, and the electromagnetic coil 45. The metal plate 49 is generally flat and disposed on a side of the housing 48 adjacent to the valve body 1. Together with the housing 48, it forms an electromagnetic circuit that acts on the electromagnetic coil 45. Both the housing 48 and the metal plate 49 are made of a magnetically conductive material. This design allows the electromagnetic field generated by the electromagnetic coil 45 to be primarily concentrated on the fixed iron core 42, resulting in a strong attraction between the fixed iron core 42 and the movable iron core 43.

[0030] Furthermore, the guide structure further includes a pin 50 extending out of the housing 48 for electrically connecting the guide structure 4 to an external power source.

[0031] Therefore, when the electromagnetic coil 45 is energized, an electromagnetic field will be generated in the pilot structure 4, and the fixed iron core 42 will generate an attraction on the movable iron core 43 with the help of this electromagnetic field, so that the movable iron core 43 overcomes the force of the pilot spring 44 and moves downward toward the fixed iron core 42, thereby driving the push rod 46 to move downward; and when the electromagnetic coil 45 is de-energized, the electromagnetic field disappears, and the movable iron core 43 will move upward away from the fixed iron core 42 under the action of the spring restoring force of the pilot spring 44, thereby driving the push rod 46 to move upward.

[0032] In addition, if Figure 1 and Figure 2 As shown, the valve body 1 is provided with a pilot port 13, which extends through the valve body 1 in a first direction. A push rod 46 is removably inserted into the pilot chamber C1 through the pilot port 13. A pilot valve 47 is provided at the lower end of the push rod 46, which extends into the pilot chamber C1. The diameter of the pilot valve 47 is larger than that of the pilot port 13. The valve body 1 is provided with an air inlet 14, which communicates with the pilot port 13 via a third flow passage p3. The third flow passage p3 is at least partially formed between the fixed iron core 42 and the valve body 1. Furthermore, the valve core 31 is provided with an exhaust port 15, which extends through the valve core 31 in the first direction. The pilot chamber C1 is connected to the exhaust port 21 via the exhaust port 15.

[0033] Therefore, when the push rod 46 moves downward in response to the drive of the movable iron core 43, the pilot valve 47 will leave the pilot port 13 on the valve body 1 and close the exhaust port 15 on the valve core 31. The high-pressure gas entering from the air inlet 14 and flowing through the third flow channel p3 can enter the pilot chamber C1 through the pilot port 13. Since the exhaust port 15 is closed, a pressure difference is formed on the upper and lower sides of the valve core 31. This pressure difference will push the valve core 31 to move downward; when the push rod 46 moves upward in response to the drive of the movable iron core 43, the pilot valve 47 will leave the exhaust port 15 and close the pilot port 13. At this time, the high-pressure gas will no longer enter the pilot chamber C1, and the high-pressure gas in the pilot chamber C1 will be discharged into the external environment through the exhaust port 21 connected to the exhaust port 15. At this time, the force of the pilot structure 4 on the valve core 31 disappears, and then the valve core 31 will move upward under the action of the elastic restoring force of the main spring 33.

[0034] Therefore, in the aforementioned two-position, three-way solenoid valve, the pilot structure 4 can drive the valve core 31 by controlling the high-pressure gas flowing through the pilot port 13. This results in a shorter response time and is suitable for operating conditions with high gas pressures and large flow passage areas. Furthermore, compared to configurations in which the valve core 31 is driven by a motor, the two-position, three-way solenoid valve utilizing the pilot structure 4 according to the present invention offers lower costs and a simpler structure.

[0035] In a preferred embodiment, the pilot valve 47 and the main valve 32 are coated with elastic material, which not only provides a better sealing effect, but also provides a buffering effect, thereby reducing the impact between the push rod 46 and the valve core 31 and the inner circumference of the valve cavity during movement.

[0036] In a preferred embodiment, a cavity is formed on the fixed iron core 42, and a protrusion that can be inserted into the cavity is formed on the movable iron core 43. Such a cavity and protrusion have shapes that are adapted to each other, for example Figure 1 and Figure 2 The truncated cone shape shown is advantageous in guiding the movement of the movable iron core 43 toward the fixed iron core 42. Figure 1 and Figure 2 As shown, the push rod extends through the cavity on the fixed iron core 42 to be fixedly connected to the movable iron core 43.

[0037] Next, combine again Figure 1 and Figure 2 The working principle of the two-position three-way solenoid valve according to the embodiment of the present utility model is described below.

[0038] like Figure 1 As shown, when the electromagnetic coil 45 is de-energized, the movable iron core 43 drives the push rod 46 to move upward under the action of the pilot spring 44, so that the pilot valve 47 at the lower end of the push rod 46 fits against the pilot port 13 to form a seal on the pilot port 13, thereby closing the communication between the third flow channel p3 and the pilot chamber C1, thereby preventing high-pressure gas from entering the pilot chamber C1 through the pilot port 13. At this point, since the pilot chamber C1 at the top of the valve core 31 is connected to the exhaust port 21 on the valve seat 2 through the exhaust port 15 on the valve core 31, the high-pressure gas in the pilot chamber C1 can be discharged into the atmosphere through the exhaust port 15 and the exhaust port 21. As a result, the aerodynamic force in the pilot chamber C1 disappears, and the pressure on the upper and lower sides of the valve core 31 is equal. Therefore, the valve core 31 can move upward under the action of the main spring 33, causing the main valve 32 at the lower end of the valve core 31 to close the first flow channel p1, thereby cutting off the connection between the first opening 11 and the second opening 12, and simultaneously opening the second flow channel p2, thereby connecting the second opening 12 with the exhaust port 21. In this state, the fluid at the second opening 12 will flow out of the exhaust port 21 through the second flow channel p2, and the solenoid valve is in the non-operating state, that is, the closed state.

[0039] like Figure 2As shown, when the electromagnetic coil 45 is energized, the fixed core 42 attracts the movable core 43 via the magnetic field induced by the electromagnetic coil 45. The movable core 43 overcomes the action of the pilot spring 44 and drives the push rod 46 downward, causing the pilot valve 47 at the lower end of the push rod 46 to move away from the pilot port 13 and downwardly abut against the exhaust port 15, sealing the exhaust port 15. At this time, high-pressure gas flows from the air inlet 14 through the third flow passage p3 and the pilot port 13 into the pilot chamber C1, acting on the upper side of the valve core 31. Under the action of this pneumatic force, the valve core 31 overcomes the force of the main spring 33 and drives the main valve 32 downward. The main valve 32 at the lower end of the valve core 31 opens the first flow passage p1, thereby connecting the first opening 11 with the second opening 12, while closing the second flow passage p2, thereby cutting off the connection between the second opening 12 and the exhaust port 21. In this state, the high-pressure fluid entering from the first opening 11 can flow into the second opening 12 via the first flow passage p1 , and the solenoid valve is in a working state, ie, an open state.

[0040] In addition, if Figure 2 As shown, since the air inlet 14 is connected to the high-pressure gas source and the exhaust port 21 is connected to the external environment, a pressure difference will be generated on the upper and lower sides of the valve core 31. This pressure difference can make the valve core 31 overcome the force of the main spring 33 and remain in place, that is, the valve core 31 remains in a position where the first opening 11 and the second opening 12 are connected to each other and the second opening 12 and the exhaust port 21 are disconnected from each other; moreover, in the pilot structure 4, when the electromagnetic coil 45 is energized, the distance between the fixed iron core 42 and the movable iron core 43 is the shortest, so the electromagnetic force generated between the two is the largest. At this time, even if the current passing through the electromagnetic coil 45 is small, the movable iron core 43 can overcome the force of the pilot spring 44 and remain in place, that is, the movable iron core 43 remains in a position attracted by the fixed iron core 42. Therefore, the solenoid valve of the present invention can reliably maintain its working state even when the current passing through the electromagnetic coil 45 is small.

[0041] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and equivalent components may be substituted without departing from the scope of the present invention. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A two-position three-way solenoid valve, characterized in that: It includes a valve body (1), a valve seat (2), a valve core assembly (3) and a pilot structure (4). The valve body (1) and the valve seat (2) are fixedly connected to each other and enclose a valve cavity, the valve core assembly (3) is accommodated in the valve cavity, the valve core assembly (3) includes a valve core (31) capable of moving in the valve cavity along a first direction, the valve cavity is divided by the valve core (31) to form a pilot cavity (C1) and a main valve cavity (C2), and the valve core (31) defines a first flow channel (p1) and a second flow channel (p2) in the main valve cavity (C2); The pilot structure (4) is connected to a side of the valve body (1) away from the valve seat (2), and the pilot structure (4) comprises a fixed iron core (42), a movable iron core (43), an electromagnetic coil (45), and a push rod (46), wherein the fixed iron core (42) is configured to move the movable iron core (43) along the first direction by means of a magnetic field induced by the electromagnetic coil (45); One end of the push rod (46) along the first direction is fixedly connected to the movable iron core (43), and the other end extends into the pilot chamber (C1) and is movably connected to the valve core (31), so that when the push rod (46) moves along the first direction in response to the movement of the movable iron core (43), the valve core (31) is allowed to move along the first direction in the valve chamber, thereby controlling the opening and closing of the first flow channel (p1) and the second flow channel (p2).

2. The two-position three-way solenoid valve according to claim 1, characterized in that: The valve body (1) is provided with a pilot port (13), which penetrates the valve body (1) along the first direction, and the push rod (46) is movably inserted into the pilot chamber (C1) through the pilot port (13).

3. The two-position three-way solenoid valve according to claim 2, characterized in that: The other end of the push rod (46) extending into the pilot cavity (C1) is provided with a pilot valve (47). The diameter of the pilot valve (47) is larger than the diameter of the pilot port (13). The pilot valve (47) comprises an elastic material.

4. The two-position three-way solenoid valve according to claim 3, characterized in that: The valve body (1) is provided with an air inlet (14), the air inlet (14) is connected to the pilot port (13) through a third flow channel (p3), and the third flow channel (p3) is at least partially formed between the fixed iron core (42) and the valve body (1); and The valve core (31) is provided with an exhaust port (15), the exhaust port (15) passes through the valve core (31) along the first direction, the valve seat (2) is formed with a discharge port (21) communicating with the external environment, and the pilot chamber (C1) can be communicated with the discharge port (21) through the exhaust port (15).

5. The two-position three-way solenoid valve according to claim 1, characterized in that: The pilot structure (4) further includes a pilot spring (44), which is sandwiched between the fixed iron core (42) and the movable iron core (43) and is used to reset the movable iron core (43) after the electromagnetic coil (45) is powered off.

6. The two-position three-way solenoid valve according to claim 1, characterized in that: The fixed iron core (42) is arranged between the movable iron core (43) and the valve body (1) along the first direction, a concave cavity is formed on the fixed iron core (42), a protrusion capable of being inserted into the concave cavity is formed on the movable iron core (43), and the push rod (46) extends through the concave cavity to be fixedly connected to the movable iron core (43).

7. The two-position three-way solenoid valve according to claim 1, characterized in that: The pilot structure (4) further includes a shell (48) and a metal plate (49), wherein the shell (48) is generally in the shape of a hollow column, the metal plate (49) is arranged on a side of the shell (48) close to the valve body (1), and can form an electromagnetic circuit together with the shell (48) to act on the electromagnetic coil (45), and the shell (48) and the metal plate (49) are both made of magnetic conductive material.

8. The two-position three-way solenoid valve according to any one of claims 1 to 7, characterized in that: The valve core assembly (3) further comprises a main spring (33), which is sandwiched between the valve core (31) and the valve seat (2) and is used to reset the valve core (31).

9. The two-position three-way solenoid valve according to any one of claims 1 to 7, characterized in that: The valve core assembly (3) further comprises a main valve (32) which is arranged at one end of the valve core (31) away from the pilot chamber (C1) and is configured to open or close the first flow passage (p1) and the second flow passage (p2) in response to movement of the valve core (31) along the first direction.

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