JP4598684B2 - Air cleaner - Google Patents

Description

  The present invention relates to an air cleaner technology for an internal combustion engine.

  Conventionally, in an internal combustion engine such as a diesel engine, the intake negative pressure in the intake system of the engine depends on the engine speed, and has a characteristic of becoming more negative as the engine speed increases. In general, the engine efficiency has a characteristic of decreasing as the intake negative pressure becomes negative. Therefore, the engine efficiency decreases at a high engine speed. Therefore, in the capacity design of the intake system of the engine, while taking into account the allowable intake negative pressure due to legal regulations, the intake negative pressure at the maximum engine speed is used as a reference, and there is a margin as much as possible to reduce the efficiency. Designs have been made with consideration given to suppressing the above.

  Also, in a dry air cleaner installed in the engine intake system, if the filtration speed of the filter element is too high from the viewpoint of dust removal performance, dust will pass through the filter element and be collected. In order to reduce the life of the filter element, it is necessary to allow sufficient air cleaner capacity while considering the pressure loss at the end of use of the filter element and the maximum engine speed in the actual operating range. Therefore, the design has been made so that the filtration rate becomes slow.

  However, from the standpoint of installation space, design, economy, etc., it is not possible to unnecessarily increase the margin when designing the capacity of the intake system, and the upper limit of the engine speed is the type and application of the engine. Depending on the engine type and application, it was necessary to individually design the intake system capacity in order to consider the balance between performance and installation space. That is, until now, there has been a problem that it is necessary to design the intake system capacity for each engine or the like.

Therefore, in order to suppress a decrease in efficiency at the time of high engine rotation, in an internal combustion engine such as a diesel engine, a bypass pipe having a variable valve is connected to the intake manifold, and the variable valve is opened and closed according to the detected intake negative pressure. Thus, a technique that makes it possible to control the intake negative pressure by changing the flow resistance of the intake passage is known (see Patent Document 1). According to this technique, since it is possible to adjust the intake negative pressure suitable for high engine speed and low engine speed, it is possible to suppress a decrease in capacity during engine high engine speed.
Japanese Patent Laid-Open No. 06-159173

  However, in the known technique, in order to control the intake negative pressure, a means for detecting the intake negative pressure is necessary, which increases the number of parts and costs. Moreover, it was very difficult to apply to existing general-purpose diesel engines, etc., because it was necessary to review the intake manifold.

  In recent years, when reduction of environmental load is regarded as important, in an internal combustion engine, by applying an EGR (Exhaust Gas Recirculation) technique, NOx (nitrogen oxide) and PM (particulate matter: It is known that Particulate Matter) is reduced and effective in reducing environmental burden. When applying EGR, it is important to properly control the exhaust gas recirculation amount, and the differential pressure between the intake negative pressure in the intake system and the exhaust back pressure in the exhaust silencer or the like can be kept constant. It is desirable for control stabilization. In view of the above situation, the present invention focuses on the air cleaner and ensures the necessary dust removal performance so that the intake negative pressure can be controlled without changing the shape of the intake manifold as much as possible. An object of the present invention is to provide a versatile air cleaner that can control intake negative pressure.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

In Claim 1, It is an air cleaner (1) arrange | positioned by an internal combustion engine, Comprising: The filter passage area | region inside this air cleaner (1) is provided with a partition plate (8), and a 1st filtration chamber (10) and It is divided into a second filtration chamber (11), a low speed filter element (6) is arranged in the first filtration chamber (10), and a high speed filter element (7) is arranged in the second filtration chamber (11). The low-speed inlet (12) is opened in the first filtration chamber (10), the high-speed intake (13) is opened in the second filtration chamber (11), and the low-speed intake (12) is opened. An inlet pipe (3) is connected, an inlet branch pipe (4) is connected to the high-speed inlet (13), and the inlet branch pipe (4) is communicated with a middle portion of the inlet pipe (3). A valve (9) is disposed on the side of the inlet branch pipe (4) where the branch pipe (4) communicates with the inlet pipe (3), Lube (9), which is constituted by a variable valve that opens and closes according to the intake negative pressure.

The air cleaner according to claim 1, wherein the valve (9) is configured by a plate-like valve body (9 a) that closes the inlet branch pipe (4), and the inlet branch pipe (4). An attachment member (15), which is a substantially half-moon shaped steel plate member, is disposed on the lower inner surface of the inlet side, and the valve body (9a) is supported rotatably with respect to the attachment member (15). The valve body (9a) is biased in a direction to close the inlet branch pipe (4) .

  As effects of the present invention, the following effects can be obtained.

In Claim 1, It is an air cleaner (1) arrange | positioned by an internal combustion engine, Comprising: The filter passage area | region inside this air cleaner (1) is provided with a partition plate (8), and a 1st filtration chamber (10) and It is divided into a second filtration chamber (11), a low speed filter element (6) is arranged in the first filtration chamber (10), and a high speed filter element (7) is arranged in the second filtration chamber (11). The low-speed inlet (12) is opened in the first filtration chamber (10), the high-speed intake (13) is opened in the second filtration chamber (11), and the low-speed intake (12) is opened. An inlet pipe (3) is connected, an inlet branch pipe (4) is connected to the high-speed inlet (13), and the inlet branch pipe (4) is communicated with a middle portion of the inlet pipe (3). A valve (9) is disposed on the side of the inlet branch pipe (4) where the branch pipe (4) communicates with the inlet pipe (3), Lube (9), since it is configured by a variable valve that opens and closes according to the intake negative pressure by opening and closing the valve, it is possible to control the intake negative pressure.
That is, by opening the valve, it is possible to limit the lower limit of the intake negative pressure, and to control the differential pressure between intake and exhaust. Also, high-speed and low-speed intake ports can be provided, and the intake air amount can be controlled according to the rotational speed.

  Moreover, since the suction path until it branches into the inlet pipe (3) and the inlet branch pipe (4) is shared by the low-speed use area side and the high-speed use area side, manufacturing cost can be reduced.

  Moreover, since it opens and closes according to the negative pressure in an inlet branch pipe (4), matching with exhaust pressure can be performed easily.

The air cleaner according to claim 1, wherein the valve (9) is configured by a plate-like valve body (9 a) that closes the inlet branch pipe (4), and the inlet branch pipe (4). An attachment member (15), which is a substantially half-moon shaped steel plate member, is disposed on the lower inner surface of the inlet side, and the valve body (9a) is supported rotatably with respect to the attachment member (15). Since the valve body (9a) is biased in the direction of closing the inlet branch pipe (4) , the plate member is overcome and released by the negative pressure in the high-speed suction passage, that is, Since the valve is configured to be opened, the intake negative pressure can be controlled at a low manufacturing cost.

  Next, embodiments of the invention will be described. First, the overall structure of an air cleaner according to an embodiment of the present invention will be described with reference to FIG. 1 or FIG. As shown in FIG. 1 or FIG. 2, the air cleaner 1 is connected to the upstream side of the intake manifold 20 of the internal combustion engine, and includes a housing 2, an inlet pipe 3, an inlet branch pipe 4, an outlet pipe 5, and a low speed filter element 6. The high-speed filter element 7, the partition plate 8, the valve 9, and the like. As shown in FIGS. 1 and 2, the housing 2 is a substantially cylindrical resin molded product, and a substantially cylindrical space is formed in the housing 2. The substantially cylindrical space formed inside the housing 2 is divided into two spaces, a first filtration chamber 10 and a second filtration chamber 11, by a partition plate 8 arranged in a direction perpendicular to the axial direction of the housing 2. It is divided into The filter chambers 10 and 11 are detachably mounted with low-speed and high-speed filter elements 7 and 8, respectively. In addition, a low-speed air inlet 12 and a high-speed air inlet 13 are formed on the circumferential side surface of the housing 2 so as to introduce outside air into the first filtration chamber 10 and the second filtration chamber 11. To be able to. In the present embodiment, the case 2 is shown as an example of a substantially cylindrical shape. However, the case 2 may have a substantially rectangular parallelepiped shape, and the material may be a steel plate or the like, and is not limited. . Further, the low-speed and high-speed filter elements 7 and 8 may be integrally formed.

  The inlet pipe 3 is a tubular member whose both ends are open, and is arranged perpendicular to the axis of the casing 2 so as to cover the low-speed inlet 12 on the peripheral surface of the casing 2. The inside of the filtration chamber 10 and the outside of the housing 2 are communicated with each other. The outlet pipe 5 is a tubular member having both ends opened, and is disposed on the side surface of the casing 2 with the axial center of the casing 2 as a concentric axis, and communicates the first filtration chamber 10 and the intake manifold 20. I am doing so. The inlet branch pipe 4 is a tubular member. A valve 9 is provided at one end on the upstream side of the intake air, and can be opened and closed. The other end on the downstream side is opened. The other end on the downstream side is disposed obliquely with respect to the axis of the housing 2 so as to cover the high-speed air inlet 13 on the peripheral surface of the housing 2. The other end, which is provided with a valve 9 and can be opened and closed, is configured to communicate with the inlet pipe 3. In other words, the inlet branch pipe 4 allows the inlet pipe 3 and the second filtration chamber 9 to communicate with each other. However, as shown in FIG. 5, the inlet branch pipe 4 can be arranged in a direction perpendicular to the axis of the housing 2, and a valve 9 can be provided at one end thereof so that it can communicate directly with the atmosphere. . Further, the arrangement position of the high-speed intake port 13 and the inlet branch pipe 4 is not limited as long as it is the outer periphery of the second filtration chamber 11.

  The partition plate 8 is a donut-shaped disk-shaped member, and is disposed inside the housing 2 in a direction perpendicular to the axial direction of the housing 2. The interior of the housing 2 is divided into two spaces, a first filtration chamber 10 and a second filtration chamber 11. In addition, a circular opening 8 a is formed at the center of the partition plate 8 so that the first filtration chamber 10 and the second filtration chamber 11 communicate with each other.

  The low speed filter element 6 is a substantially cylindrical filter member obtained by molding paper or the like, and has a hollow portion 6a in the cylinder. And it is set as the structure which distribute | circulates external air from the cylindrical surface to the said hollow part 6a, and collects the dust etc. which are contained in external air. The low-speed filter element 6 is sandwiched between the housing 2 and the partition plate 8 and is configured to be easily detachable. That is, the outside air sucked into the first filtration chamber 10 from the inlet pipe 3 is filtered by the low speed filter element 6 and is sent to the intake manifold 20 from the outlet pipe 5.

  Similarly to the low speed filter element 6, the high speed filter element 7 is a substantially cylindrical filter member obtained by molding paper or the like, and has a hollow portion 7a in the cylinder. And it is set as the structure which distribute | circulates external air from the cylindrical surface to the said hollow part 7a, and collects the dust etc. which are contained in external air. The high-speed filter element 7 is hooked by a partition plate 8 or the like, and is configured to be easily detachable. That is, the outside air sucked into the second filtration chamber 11 from the inlet pipe 3 through the inlet branch pipe 4 is filtered by the high-speed filter element 7 and passes through the opening 8a to the first filtration chamber 10 (specifically, for low-speed use). The air is sent to the hollow portion 6a) in the filter element 6 and then sent to the intake manifold 20 from the outlet pipe 5. The specifications (shape and material) of the filter elements 6 and 7 are not limited.

  In such a configuration, the outside air is first introduced through the inlet pipe 3 and then introduced as it is into the first filtration chamber 10 through the inlet pipe 3, or from the middle of the inlet pipe 3 to the inlet branch pipe 4. And is introduced into the second filtration chamber 11, filtered by the low-speed or high-speed filter elements 7, 8, and sent to the intake manifold 20 through the outlet pipe 5. The above is the description of the overall configuration of the air cleaner according to one embodiment of the present invention.

  Next, the detailed structure of the valve, which is the main part of the present invention, will be described with reference to FIGS.

  As shown in FIG. 2, a valve body 9a of a valve 9 is disposed at an end of the inlet branch pipe 4 on the intake inlet side so as to close the end so as to be opened and closed. The valve body 9a is a substantially elliptical steel plate member having elasticity, and one end portion in the major axis direction of the ellipse is bent to be processed into a substantially square shape in cross section. An attachment member 15, which is a substantially half-moon shaped steel plate member, is disposed on the lower inner surface on the inlet side of the inlet branch pipe 4. The bent portion of the valve body 9a is fixed to the mounting member 15 by spot welding (or rivets, screws, etc.). At this time, the valve body 9a is attached in a state where the inner surface of the inlet branch pipe 4 is in contact with the valve body 9a so that the valve body 9a is urged in a direction to close the inlet branch pipe 4 due to the elasticity of the valve body 9a. ing. In the present embodiment, the valve body 9a is fixed to the lower inner surface, but may be fixed to the upper inner surface, and the mounting direction is not limited. Further, in this embodiment, the valve 9 is provided at the upstream end of the inlet branch pipe 4, but the valve 9 is disposed at the downstream end of the inlet branch pipe 4 as desired by the second filtration chamber 11. It is also possible to use this mode.

  In such a configuration, when the engine speed is low, the valve body 9a is not bent even when the valve body 9a is urged by the intake pressure and intake outside air generated by the intake action by the engine, and the inlet branch pipe 4 is closed. The state is maintained (region A in FIG. 6), and the outside air does not flow into the second filtration chamber 11 from the inlet branch pipe 4. In this case (that is, in the range of region A), the intake negative pressure increases / decreases as the engine speed increases / decreases.

  Further, when the engine speed increases, the negative pressure level of the intake pressure by the engine increases, and the valve body 9a is urged by the intake pressure generated by the intake action by the engine and the intake outside air to cause deflection, the inlet The branch pipe 4 is opened (point X in FIG. 6), and the outside air flows into the second filtration chamber 11 from the inlet branch pipe 4. At this time, according to the urging force generated by the intake pressure and the intake outside air (that is, according to the engine speed), the opening degree (that is, the amount of deflection) of the valve body 9a changes to maintain the intermediate opening degree. At that time (region B in FIG. 6), the pressure on the downstream side of the valve body 9a (that is, the intake negative pressure) is kept constant.

  Further, when the engine speed further increases, the negative pressure of the intake pressure by the engine further increases, and the opening degree of the valve body 9a becomes maximum (point Y in FIG. 6), thereafter (that is, in FIG. 6) In the range of the region C), the intake negative pressure increases / decreases as the engine speed increases / decreases again.

  As shown in FIG. 3, a valve body 9b of a valve 9 is disposed at an end of the inlet branch pipe 4 on the intake inlet side so as to close the end so as to be opened and closed. The valve body 9b is a substantially elliptical steel plate member having rigidity, and has a shape in which one end portion of the ellipse in the major axis direction is linearly cut parallel to the minor axis. An attachment member 15, which is a substantially half-moon shaped steel plate member, is disposed on the lower inner surface on the inlet side of the inlet branch pipe 4. The end of the valve body 9b having the cut-out portion and the mounting member 15 are connected via a hinge 14, and the valve body 9b is supported so as to be reciprocally rotatable inside the inlet branch pipe 4. In the present embodiment, the embodiment is fixed to the lower inner surface, but may be fixed to the upper inner surface, and does not limit the mounting direction. Further, in this embodiment, the valve 9 is provided at the upstream end of the inlet branch pipe 4, but the valve 9 is disposed at the downstream end of the inlet branch pipe 4 as desired by the second filtration chamber 11. It is also possible to use this mode.

  As shown in FIG. 4, a torsion spring 18 is externally fitted to the rotation shaft 14a of the hinge 14, and one end of the torsion spring 18 abuts on the downstream side surface of the valve body 9b. The other end is in contact with the inner wall or the like of the inlet branch pipe 4, and the valve body 9 b is always urged so as to close the inlet branch pipe 4 by a torsion spring 18. is doing. However, the rotation shaft 14a can be extended to the outside of the inlet branch pipe 4 and the torsion spring 18 can be arranged in the inlet branch pipe 4 to facilitate maintenance and adjustment.

  In such a configuration, when the engine speed is low and the urging force applied to the valve body 9b caused by the intake pressure generated by the intake action by the engine and the intake outside air is less than the urging force of the torsion spring 18, the valve body 9b Does not rotate and maintains the state where the inlet branch pipe 4 is closed (region A in FIG. 6), and outside air does not flow into the second filtration chamber 11 from the inlet branch pipe 4. In this case (that is, in the range of region A), the intake negative pressure increases / decreases as the engine speed increases / decreases.

  Further, when the engine speed increases and the urging force to the valve body 9b generated by the intake pressure and the intake outside air generated by the intake action by the engine increases and exceeds the urging force by the torsion spring 18, the valve body 9b , The inlet branch pipe 4 is opened (point X in FIG. 6), and the outside air flows into the second filtration chamber 11 from the inlet branch pipe 4. At this time, according to the urging force generated by the intake pressure and the intake outside air (that is, according to the engine speed), the opening degree (that is, the rotation angle) of the valve body 9b changes to maintain the intermediate opening degree. When the engine is in operation (region B in FIG. 6), the pressure on the downstream side of the valve 9 (ie, intake negative pressure) is kept constant.

  Further, when the engine speed further increases, the urging force to the valve body 9b generated by the intake pressure generated by the intake action by the engine and the intake outside air further increases, and the opening degree of the valve 9 becomes maximum (the point in FIG. 6). Y), and thereafter (region C in FIG. 6), and the exhaust back pressure increases and decreases as the engine speed increases and decreases.

  As shown in FIG. 4, a valve body 9c of the valve 9 is disposed at an end portion of the inlet branch pipe 4 on the intake inlet side so as to close the end portion so as to be opened and closed. The valve body 9c is a rigid, substantially elliptical steel plate member, and has a shape in which one end of the ellipse in the major axis direction is linearly cut parallel to the minor axis. An attachment member 15, which is a substantially half-moon shaped steel plate member, is disposed on the lower inner surface on the inlet side of the inlet branch pipe 4. The end of the valve body 9c having the cut-out portion and the attachment member 15 are connected via a hinge 14, and the valve body 9c is supported so as to be reciprocally rotatable inside the inlet branch pipe 4. In the present embodiment, the embodiment is fixed to the lower inner surface, but may be fixed to the upper inner surface, and does not limit the mounting direction. Further, in this embodiment, the valve 9 is provided at the upstream end of the inlet branch pipe 4, but the valve 9 is disposed at the downstream end of the inlet branch pipe 4 as desired by the second filtration chamber 11. It is also possible to use this mode.

  As shown in FIG. 4, one end of a spring 19 is brought into contact with the downstream side surface of the valve body 9 c, and the other end of the spring 19 is fixed in the inlet branch pipe 4 by a fixing member 16. The spring 19 is attached in a state shortened from the natural length, and is always biased in the direction in which the spring 19 extends, so that the valve body 9c is biased so as to block the inlet branch pipe 4. It is composed. The fixing member 16 can be displaced by adjusting the bolt 17, and the biasing force by the spring 19 can be easily adjusted. However, the spring 19 may be arranged as a tension spring between the opposite surface of the valve body 9c and the inside of the inlet pipe 3.

  In such a configuration, when the engine speed is low and the urging force to the valve body 9c generated by the intake pressure generated by the intake action by the engine and the intake outside air is less than the urging force by the spring 19, the valve body 9c rotates. Without maintaining the inlet branch pipe 4 closed (region A in FIG. 6), the outside air does not flow into the second filtration chamber 11 from the inlet branch pipe 4. In this case (that is, in the range of region A), the intake negative pressure increases / decreases as the engine speed increases / decreases.

  Further, when the engine speed increases and the urging force to the valve body 9c generated by the intake pressure and intake outside air generated by the intake action by the engine increases and exceeds the urging force by the spring 19, the valve body 9b rotates downstream. Then, the inlet branch pipe 4 is opened (point X in FIG. 6), and the outside air flows into the second filtration chamber 11 from the inlet branch pipe 4. At this time, according to the urging force generated by the intake pressure and the intake outside air (that is, according to the engine speed), the opening degree (that is, the rotation angle) of the valve body 9c changes to maintain the intermediate opening degree. When the engine is in operation (region B in FIG. 6), the pressure on the downstream side of the valve 9 (ie, intake negative pressure) is kept constant.

  Further, when the engine speed further increases, the urging force to the valve body 9c generated by the intake pressure generated by the intake action by the engine and the intake outside air further increases, and the opening degree of the valve 9 becomes maximum (the point in FIG. 6). Y), and thereafter (region C in FIG. 6), and the exhaust back pressure increases and decreases as the engine speed increases and decreases.

  As shown in the above description, the air cleaner 1 is provided in an internal combustion engine, and the partition plate 8 for partitioning the filter passage area is provided inside the air cleaner 1 to provide a plurality of areas (that is, the first filtration chamber 10 and the second filtration chamber 10). It is divided into filtration chambers 11), and each area is provided with an intake port, that is, a low-speed intake port 12 and a high-speed intake port 13), and at least one of the intake ports (that is, the high-speed intake port 13 in this embodiment). A valve 9 is provided in the inlet branch pipe 4) connected to the pipe so that it can be opened and closed. Thus, the intake negative pressure can be controlled by opening and closing the valve 9. That is, by opening the valve 9, it is possible to limit the lower limit of the intake negative pressure and to control the differential pressure of intake and exhaust. Further, high-speed and low-speed intake ports (that is, the inlet pipe 3 and the inlet branch pipe 4) can be provided, and the intake air amount can be controlled according to the rotational speed.

  In the air cleaner 1, suction paths (that is, the inlet pipe 3 and the inlet branch pipe 4) are connected to the respective inlets (that is, the low-speed inlet 12 and the high-speed inlet 13), respectively, and the inlet pipe 3 and the inlet branch are connected. The pipe 4 is configured to communicate with one suction path (that is, the inlet pipe 3). Thereby, since the inlet pipe 3 until it branches off is shared by the 1st filtration chamber 10 and the 2nd filtration chamber 11, manufacturing cost can be reduced.

  In the air cleaner 1, the valve 9 is constituted by a variable valve that opens and closes according to the intake negative pressure. Thereby, since it opens and closes according to the negative pressure in a suction passage, matching with exhaust pressure can be performed easily.

  In the air cleaner 1, the valve 9 is constituted by a plate-like member (that is, the valve bodies 9 a, 9 b, and 9 c) that closes the inlet branch pipe 4, and the valve bodies 9 a, 9 b, and 9 c are closed in the direction to close the inlet branch pipe 4. The configuration is energized. As a result, the plate member (valve elements 9a, 9b, 9c) is overcome and opened by the negative pressure in the second filtration chamber 11, that is, the valve 9 is opened. The intake negative pressure can be controlled at a low manufacturing cost.

  Further, as shown in the above description, an exhaust silencer equipped with a mechanism that can keep the intake negative pressure constant in the actual use region and keep the exhaust back pressure constant, as in region B in FIG. By combining with the above, it is possible to easily maintain a constant differential pressure between the intake negative pressure and the exhaust back pressure. Thereby, the control stabilization at the time of EGR adoption is easily realizable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 4 is a partial cross-sectional side view showing details of the valve mounting portion according to the first embodiment. The side surface partial sectional view which showed the detail of the valve | bulb attaching part which concerns on Example 2. FIG. The side surface partial sectional view which showed the detail of the valve | bulb attaching part which concerns on Example 2. FIG. The side surface partial sectional view which showed another structure of the valve attachment position. The figure which showed the relationship between an engine speed and exhaust back pressure.

DESCRIPTION OF SYMBOLS 1 Air cleaner 3 Inlet pipe 4 Inlet branch pipe 8 Partition plate 9 Valve 10 1st filtration chamber 11 2nd filtration chamber

Claims (2)

An air cleaner (1) disposed in an internal combustion engine, wherein a filter passage region inside the air cleaner (1) is provided with a partition plate (8), and a first filtration chamber (10) and a second filtration chamber ( 11), a low speed filter element (6) is disposed in the first filtration chamber (10), and a high speed filter element (7) is disposed in the second filtration chamber (11). A low-speed intake port (12) is opened in the filtration chamber (10), a high-speed intake port (13) is opened in the second filtration chamber (11), and an inlet pipe (3) is connected to the low-speed intake port (12). The inlet branch pipe (4) is connected to the high-speed intake port (13), the inlet branch pipe (4) is communicated with a middle portion of the inlet pipe (3), and the inlet branch pipe (4) Is provided with a valve (9) on the side of the inlet branch pipe (4) in the portion communicating with the inlet pipe (3). Air cleaner characterized by being configured by a variable valve to be opened or closed in response to a negative pressure. 2. The air cleaner according to claim 1, wherein the valve (9) is configured by a plate-like valve body (9 a) that closes the inlet branch pipe (4), and an inlet-side lower inner surface of the inlet branch pipe (4). Is provided with a mounting member (15) which is a substantially half-moon shaped steel plate member, and the valve body (9a) is rotatably supported with respect to the mounting member (15). Is urged in a direction to close the inlet branch pipe (4) .

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