JP2019105378A - Flow channel change-over valve - Google Patents

Abstract

To provide a flow channel change-over valve capable of eliminating a seal member such as O-ring for preventing leakage among a plurality of outlets, not requiring any severe size management or high-precision processing forming technology, capable of positively preventing leakage among the outlets and further restricting a processing and assembling cost or product cost.SOLUTION: A valve body 40 is integrally arranged at the lower end part of a valve shaft 30. The valve body 40 has at least one of opening passages 41, 42 selectively opening an inlet 20 and each of outlets 21, 22. The upper surface of the valve body 40 is pushed against valve seats 15A, 15B with fluid pressure in a valve main body 6. Under this state, a valve shaft 30 with the valve body 40 is turned to selectively take any one of a first flowing state in which fluid flows from the inlet 20 to the outlet 21 through the opening passage 41 and a second flowing state in which fluid flows from the inlet 20 to the outlet 22 through the opening passage 42.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a flow path switching valve such as a three-way valve or a four-way valve having at least one inlet and two outlets, and in particular, a flow path suitable for use in switching the flow path in a hot water supply facility. It relates to a switching valve.

  FIG. 10 shows the main part of an example of a conventional hot water supply system in which a three-way valve, which is one of flow path switching valves having one inlet and two outlets, is used (see also Patent Document 1). Basically, the hot water supply facility 100 in the illustrated example is a hot water storage tank 110 that supplies water to the lower part thereof and performs hot water supply from the upper part thereof, a compressor 131, a hot water heat exchanger (hot water water heater) 132, an expansion valve 133, and A heat pump type hot water heating source 130 having an air heat exchanger 134 and the like, a boiling pump 120 for circulating hot water between the hot water storage tank 110 and the heating source 130, one inlet 160 and two outlets 161 , 162 and a three-way valve 150 as a flow passage switching valve.

  The three-way valve 150 is, for example, an electronically controlled motorized valve whose flow passage switching operation or the like is controlled based on the temperature or the like of hot and cold water detected by a temperature sensor provided at a required location. The first flow state of flowing hot water from the inflow port 160 to the first outflow port 161 and the second flow state of flowing hot water to the second outflow port 162 from the inflow port 160 can be selectively taken. If the hot water from the heating source 130 is usually at a high temperature, the first flow state is taken, and the hot water is returned to the top of the storage tank 110, and the hot water from the heating source 130 is at a low temperature. In the second circulation state, the low temperature water is returned to the lower part of the storage tank 110 and is again sent to the heating source 130 by the boiling pump 120.

Unexamined-Japanese-Patent No. 2004-257583

  In the flow path switching valve such as the three-way valve used in the conventional hot water supply system as described above, fluid leaks to the second outlet side in the first flow state (inflow port → first outlet) At least the first outlet and the second outlet in order to prevent the fluid from leaking to the first outlet side in the second flow state (inlet → second outlet). In order to provide a sealing material such as an O-ring, it is necessary to provide an annular mounting groove or the like on the valve body etc. I did not like the product cost to be high.

  Moreover, in the flow path switching valve used for the hot water supply facility etc., the fluid pressure in the pipe connected to the outlet becomes unexpectedly high due to freezing etc. A high pressure (reverse pressure) in the reverse direction may be applied, and there is a risk that the flow path switching valve, piping, etc. may be broken by such reverse pressure.

  In order to avoid this, for example, it is conceivable to provide a flow passage that bypasses the flow passage switching valve and interpose a relief valve that opens at a predetermined pressure or more in the flow passage. As the number of parts increases, the piping connection work also takes a lot of time and effort, which leads to an increase in the cost of equipment.

  The present invention has been made in view of the above problems, and the object of the present invention is to eliminate the need for a sealing material such as an O-ring for preventing leakage between a plurality of outlets, and to strictly control dimensional control. It is possible to reliably prevent the leak between the outlets without requiring high precision processing and molding technology, and it is also possible to provide a relief function to effectively release the back pressure, processing and assembly cost, product An object of the present invention is to provide a flow path switching valve capable of keeping the cost low.

  In order to achieve the above object, the flow path switching valve according to the present invention basically comprises a valve shaft, a drive source for rotationally driving the valve shaft, an inlet, a plurality of outlets, the valve A valve shaft insertion portion into which a shaft is rotatably inserted, and a valve body having a valve seat provided on a lower outer periphery of the valve shaft insertion portion An outflow opening serving as a start end of the valve stem is formed, and a thick disc-like or short cylindrical valve body is integrally provided at a lower end portion of the valve stem projecting downward from the valve seat, and the valve body An attached valve shaft is slidable within a predetermined range in the axial direction of the valve shaft fitting portion, and a valve body accommodating portion for accommodating the valve body is provided on the lower side of the valve seat, and the valve The inlet is provided on the lower side of the body housing, and the valve body has a cylindrical portion provided with the plurality of outlets at the outer peripheral portion thereof. The lower portion of the cylindrical portion of the main body member and the valve seat are divided into a body member and an inlet member having the inflow port and the upper portion of the cylindrical portion of the main body member is internally fitted and fixed thereto. And the upper end portion of the inflow member define the valve body accommodating portion, and the upper end portion of the inflow member is a stopper that prevents the valve body from moving downward from the lower surface of the valve seat by a predetermined distance or more The valve body has at least one open passage for selectively opening the inlet and the outlet, and by rotating the valve shaft with the valve body. At least a first flow state in which the fluid flows from the inlet to the one of the outlets through the open passage, and a fluid from the inlet through the open passage to the other of the outlet Selectively with the second distribution state flowing to one of Ri is get way.

  In a preferred aspect, the valve body mounted valve stem is pushed up by the pressure of the fluid flowing into the inflow port so that the upper surface of the valve body is pressed against the valve seat.

  In another preferred embodiment, when the pressure at any one of the outlets is increased by a predetermined pressure or more, the valve stem with a valve is depressed to form a gap between the valve seat and the upper surface of the valve. The pressure on the outlet side is thereby released to the inlet side.

  The valve body is preferably configured such that an upper surface other than the open passage can be in close contact with the valve seat so as to seal the space between the outlets in a watertight manner.

  In this case, in a preferred embodiment, the upper surface of the valve body other than the open passage is a flat smooth surface.

  In another preferred embodiment, the valve shaft is provided with a serration shaft, and the drive source is provided with a serration fitting hole in which the serration shaft is axially slidably inserted, and the valve body is provided with the flow The distance between the upper end of the serration shaft and the upper terrace surface provided above the serration shaft in the serration fitting hole in the state of taking the lowest position in contact with the upper end of the entrance member is The distance from the highest position where the valve body is pressed against the valve seat to the lowest position where it abuts on the upper end of the inflow member is longer.

  In another preferred embodiment, the drive source is provided with a fitting hole in which the upper end portion of the valve stem is slidably fitted in the axial direction and the upper surface is closed, and the valve body is the inlet member. The distance between the upper end of the valve stem and the upper surface of the fitting hole in the lowermost position in contact with the upper end is the distance from the highest position where the valve body is pressed against the valve seat It is longer than the distance to the lowest position in contact with the upper end of the inlet member.

  In the flow path switching valve according to the present invention, the fluid pressure in the valve body is used to press the upper surface of the valve body against the valve seat to seal between the respective outlets, so that between the respective outlets. It is possible to eliminate the need for sealing materials such as O-rings for sealing, and to reduce processing and assembly costs and product costs.

  Also, the valve stem with a valve body can be of a relatively simple configuration, and is pushed up by the fluid pressure in the valve body so that the upper surface of the valve body is in close contact with the valve seat. The required sealability can be easily secured between the respective outlets without requiring high-precision processing and molding techniques, which also can lower the processing and assembly costs and the product costs.

  In addition, when the pressure on any of the outlet side increases by a predetermined pressure or more, the valve body receives a reverse pressure to push down the valve body, thereby forming a gap between the valve body and the valve seat, thereby The counterpressure on the outlet side escapes to the inlet side through the gap. As described above, since the flow path switching valve of the present invention can have a relief function to effectively release the reverse pressure, it is possible to effectively avoid the failure of the flow path switching valve or the piping system due to the reverse pressure. In addition, since it is not necessary to provide a relief valve separately in the flow path, it is possible to suppress the cost increase of the equipment.

BRIEF DESCRIPTION OF THE DRAWINGS The perspective view which shows the external appearance of one Example of the flow-path switching valve concerning this invention. The partial notch sectional view which shows the 1st distribution state of the said one Example. The half section perspective view which shows the 1st distribution state of the said one Example. The partial notch sectional view which shows the 2nd distribution state of the said one Example. The half section perspective view which shows the 2nd distribution state of the said one Example. (A) UU sectional view of FIG. 2, (B) VV sectional view of FIG. FIG. 7 is a partial cutaway cross-sectional view provided to explain the occurrence of a back pressure in the embodiment. The perspective view which shows the valve shaft with a valve body of the said one Example. The perspective view which shows the main body member of the said one Example. The schematic block diagram which shows the principal part of an example of the conventional hot-water supply equipment in which the flow-path switching valve which has one inflow port and two outflow ports was used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an external perspective view showing an embodiment of a flow path switching valve according to the present invention, and FIGS. 2 and 3 are partially cutaway sectional views showing a first flow state of the above-mentioned embodiment and a half sectional perspective view FIGS. 4 and 5 are a partially cutaway sectional view and a half sectional perspective view showing a second flow state of the above-mentioned embodiment. In FIG. 1 to FIG. 5, the parts (the inside of the motor 5 and the like) which are not so necessary for the understanding of the present invention are omitted from the illustration and the hatching. Further, in each drawing, a gap formed between members, a separation distance between members, and the like may be drawn in an exaggerated manner to facilitate understanding of the invention and for convenience of drawing. is there.

  Furthermore, in the present specification, the descriptions representing the positions and directions such as upper and lower, right and left, front and back, etc. are added for convenience according to the drawings to avoid complicated explanation, and the positions and directions in the actual use state It does not refer to

  The flow path switching valve 1 of the illustrated embodiment is one used in a hot water supply system as shown in FIG. 10 described above (corresponding to the reference numeral 150 in FIG. 10), basically comprising a valve shaft 30 and the valve It has a motor 5 as a drive source for rotationally driving the shaft 30, and a valve body 6 to which the motor 5 is attached and fixed on the upper side.

  The valve main body 6 is made of a synthetic resin, and is divided into a main body member 7 and an inflow port member 9 in order to facilitate molding and the like.

  The main body member 7 has a base portion 8 having an upper short cylindrical portion 8A and a lower cylindrical portion 8B, as is well understood by referring to FIG. 9 in addition to FIGS. A stepped cylindrical first outlet (joint) 21 and a second outlet (joint) 22 are provided on the outer peripheral portion (left and right side portions) of the upper and lower portions so as to face each other.

  Also, mounting supports 7f, 7f are provided on the front and rear of the upper portion of the upper short cylindrical portion 8A, and when mounting and fixing the motor 5 to the main body member 7, the motor 5 is mounted on the mounting supports 7f, 7f. The motor 5 and the main body member 7 are fastened and fixed with two screws 15 on the front and rear sides, with screwing portions 5f and 5f provided on the front and rear of the lower part of the above.

  The upper short cylindrical portion 8A of the base portion 8 is provided with a valve shaft insertion portion 12 so as to extend longitudinally through the center of the upper short cylindrical portion 8A, and a circumferential surface opening opens to the first outlet 21 side. And the lower L-shaped first outlet 23 having the lower surface opening, and the inverted L-shaped second outlet 24 having the peripheral surface opening opening to the second outlet 22 side and the lower surface It is formed symmetrically left and right with an angular spacing of.

  More specifically, the lower opening of each of the first outlet 23 and the second outlet 24 has a semi-circular curved groove at both ends or a fan shape having a central angle of 100 ° or more, and the lower end has an upper portion The lower end portions of the first outflow opening 23 and the second outflow opening 24 project downward from the lower end surface 8a (see FIG. 9) of the short cylindrical portion 8A, and the upper surfaces of the valve body 40 to be described later Valve seats 15A and 15B. In other words, the valve seat 15A, 15B is formed of a frame-like convex portion having a predetermined width and the same outer shape as the edge portion defining the first outflow opening 23 and the second outflow opening 24 and the lower surface The valve seat surface) is a flat smooth surface orthogonal to the center line O of the valve shaft insertion portion 12 (rotational axis of the valve shaft 30). The width of the lower surface opening portion of the first outflow opening 23 and the second outflow opening 24 is slightly larger than the width of the opening-like passages 41 and 42 formed in the valve body 40 described later, and the length (central angle) The semicircular portions at both ends are made longer than the lengths (central angles) of the open channels 41 and 42 (see also FIG. 6).

  On the other hand, the inflow member 9 has a funnel-shaped insertion hole serving as the inflow port 20 on the inner peripheral side, and a bowl-like portion 9a on which the lower cylindrical portion 8B of the base portion 8 of the main body member 7 is placed Also, it has a projecting insertion portion 9b which protrudes upward from the collar portion 9a and is inserted into the lower part of the lower cylindrical portion 8B, and the collar portion 9a and the lower cylindrical portion 8B are fixed by ultrasonic welding or the like. It is done.

  A valve that pivotably accommodates a valve body 40 described later by the lower portion of the lower cylindrical portion 8B, the lower surface 8a of the base portion 8, and the protruding insertion portion 9b (upper end surface) of the inflow member 9 Body accommodation portion 14 is defined. In addition, the protruding insertion portion 9b of the inflow member 9 functions as a stopper that prevents the valve body 40 from moving down from the lower surface (the valve seat surface) of the valve seats 15A and 15B by a predetermined distance or more See Figure 7).

  In the valve main body 6, the valve body accommodation portion 14 and the inflow port 20 are disposed on the center line O of the valve shaft fitting portion 12, and the first flow is formed on the common center line C orthogonal to the center line O. An outlet 21 and a second outlet 22 are arranged.

  The valve shaft 30 has the D-cut convex portion 31 for positioning in the circumferential direction at its top, and the rotational driving force of the rotor of the motor 5 is reduced at the top, as is better understood with reference to FIG. An involute serration shaft 32 to be transmitted through a gear mechanism is provided, and on the lower side of the serration shaft 32, there is a mounting groove consisting of a three-step flange 34 to which the O-rings 35, 35 are mounted. Provided (the portion of the valve shaft 30 to which the O-rings 35, 35 are attached is referred to as the O-ring mounting portion 33), and a thick disc-like valve body 40 is integrally provided at the lowermost portion. (The valve stem 30 and the valve body 40 are one-piece thing). The valve shaft 30 with the valve body 40 is capable of sliding the valve shaft insertion portion 12 in a predetermined range in the axial direction (vertical direction).

  In detail, in the motor 5, a support portion 57 for rotatably supporting the output gear 51 of the reduction gear mechanism is provided, and the serration shaft 32 is axially formed on the boss 52 of the output gear 51. A serration fitting hole 53 which is slidably fitted is provided, and a D-shaped fitting hole 54 in which the D-cut convex portion 31 is fitted is continuously provided on the upper side of the serration fitting hole 53. In this case, the valve shaft 30 with the valve body 40 is the valve as shown in FIGS. 1 to 5, the highest position where the valve body 40 is pressed against the valve seats 15A and 15B, and as shown in FIG. The valve shaft 30 with the valve body 40 is at the lowermost position so that the body 40 can assume the lowermost position (lower by a distance K from the highest position) where the body 40 contacts the upper surface of the projecting insertion portion 9b of the inlet member 9. In the taking state (FIG. 7), between the upper end of the serration shaft 32 and the upper terraced surface 53a of the serration fitting hole 53, and the upper end of the D cut convex part 31 and the upper face 54a of the D-shaped fitting hole 54. And a space corresponding to a distance L longer than the distance K is provided.

  In the valve body 40, two open channels 41, 42 (first open channels 41) for selectively opening the inlet 20 and the first outlet 21 or the inlet 20 and the second outlet 22. , Second open channels 42) are provided at an angular interval of 90 °. Each of the open channels 41, 42 has a fan shape with a central angle of 70 ° to 80 °, and as described above, the width and length (central angle) of the first outlet 23 and the second outlet 24 are the same. It is smaller than that of the lower opening part.

  Further, the upper surfaces of the valve body 40 other than the opening passages 41 and 42 can be in close contact with the lower surfaces (valve sheet surfaces) of the valve seats 15A and 15B so as to seal between the outlets 21 and 22 in a watertight manner. As such, it is a flat and smooth surface.

  Here, the position of the valve body 40 in the rotational direction with respect to the valve seats 15A and 15B is the position of the valve seat 15A (first outflow opening 23) as shown in FIG. 2, FIG. 3 and FIG. The state where the opening-like passage 41 is located directly below is the reference (first flow state), and is a state rotated 90 ° counterclockwise from the first flow state, that is, FIG. 4, FIG. 5, FIG. A state in which the opening-like passage 42 is positioned directly below the valve seat 15B (the second outflow opening 24) as shown in (B) is a second flow state.

  When the flow path switching valve 1 of the present embodiment having the configuration as described above is incorporated as a three-way valve indicated by reference numeral 150 into a hot water supply system as shown in FIG. The shaft 30 acts on fluid (hot water) pressure (pressure acting on the lower side of the O-ring mounting portion 33 of the valve shaft 30) in the valve main body 6 and atmospheric pressure (upper side of the O-ring mounting portion 33 of the valve shaft 30). And the pressure of the fluid (hot water) flowing into the inlet 20 and flowing to the first outlet 21 or the second outlet 22, the upper surface of the valve body 40 is The seat 15A, 15B is pressed, and the upper surface of the seat 15A, 15B can be turned while being pressed against the valve seat 15A, 15B.

  In this case, the valve shaft 30 with the valve body 40 is pushed up, and the upper surface of the valve body 40 is pressed against the valve seats 15A and 15B, thereby sealing between the respective outflow ports 21 and 22 in a watertight manner. By rotating the valve shaft 30 in a state in which the body 40 is pressed, the first flow state in which the fluid flows from the inlet 20 to the first outlet 21 via the first open passage 41, and the fluid It is possible to selectively take the second flow state of flowing from the inlet 20 to the second outlet 22 through the second open passage 42.

  That is, as shown in FIGS. 2 and 3, when the first open passage 41 comes directly below the valve seat 15A, which is the lower end of the first outlet 23, the fluid is discharged from the outlet 20 to the first A first flow state of flowing from the open channel 41 to the first outlet 23 to the first outlet 21 is taken.

  On the other hand, when the valve body 40 is rotated about 90 degrees counterclockwise from the first flow state, the second opening-like passage 42 is the lower end portion of the second outflow opening 24 as shown in FIG. 4 and FIG. And the second flow state in which the fluid flows from the outlet 20 → the second open passage 42 → the second outlet 24 → the second outlet 22 is taken at this time. .

  As described above, in the flow path switching valve 1 of the present embodiment, the fluid pressure in the valve main body 6 is used to push up the valve shaft 30 with the valve body 40 to press the upper surface of the valve body 40 against the valve seats 15A and 15B. Is designed to seal between the first outlet 21 and the second outlet 22 so that no seal material such as an O ring is required to seal between the first outlet and the second outlet. And the processing and assembly costs and product costs can be kept low.

  Further, since the valve shaft 30 with the valve body 40 has a relatively simple structure and is pushed up by the fluid pressure in the valve body 6 so that the upper surface of the valve body 40 is in close contact with the valve seats 15A and 15B, The required sealability can be easily secured between the first outlet 21 and the second outlet 22 without requiring strict dimensional control or high-precision processing and forming techniques.

  Further, as shown in FIG. 7, when, for example, the first flow state (inflow port 20 → first outflow port 21) is taken, the pressure on the second outflow port 22 side increases by a predetermined pressure or more. A reverse pressure is applied to (the upper surface of) the valve body 40, and the valve shaft 30 with the valve body 40 is slightly inclined or pushed down, and between the lower surface (the valve seat surface) of the valve seats 15A and 15B and the upper surface of the valve body 40 As a result, the pressure on the second outlet 22 side is released to the inlet 20 side. Under the present circumstances, the valve body 40 descend | falls until it contacts the upper end of the protrusion insertion part 9b of the inflow member 9, and the further descent | fall is prevented (the protrusion insertion part 9b is valve member 40). Function as a stopper to prevent the

  As described above, since the flow path switching valve 1 of the present embodiment can be provided with a relief function for effectively releasing the back pressure, the flow path switching valve 1 or the flow path switching valve 1 due to the back pressure generated due to freezing etc. The failure of the piping system can be effectively avoided, and since it is not necessary to separately provide a relief valve in the flow path, it is possible to suppress the cost increase of the equipment.

  In the above embodiment, although the three-way valve having two outlets as the flow path switching valve is illustrated, the present invention is not limited thereto, and three or four outlets are provided to form a four-way valve or five-way valve You can also Further, the configuration of the valve body is not limited to that of the above embodiment, and various aspects can be adopted. Specifically, for example, while providing the first to fourth outlets at 90 ° intervals on the same plane, providing one open passage in the valve body, the valve body is rotated by 90 °, 180 °, 270 ° In each case, the inlet and each outlet may be selectively opened.

  Further, in the above embodiment, although the valve stem 30 and the valve body 40 are manufactured as an integral body, it is of course possible to assemble them integrally after manufacturing them separately.

DESCRIPTION OF SYMBOLS 1 flow-path switching valve 5 motor 6 valve main body 7 body member 8 base | substrate part 9 inflow member 12 valve shaft fitting part 14 valve body accommodating part 15A, 15B valve seat 20 inflow port 21 1st outflow port 22 2nd outflow port 23 1st outflow opening 24 2nd outflow opening 30 valve stem 40 valve body 41, 42 opening like passage

Claims (7)

Valve shaft, drive source for rotationally driving the valve shaft, inlet, plural outlets, valve shaft insertion portion into which the valve shaft is rotatably inserted, and valve shaft insertion A valve body having a valve seat provided on the lower periphery of the part;
The valve seat is formed with an outlet opening which is a starting end of each outlet, respectively.
A thick disc-like or short cylindrical valve body is integrally provided at a lower end portion of the valve stem projecting downward from the valve seat, and the valve stem with the valve body is a shaft fitting portion of the valve stem It is possible to slide in a predetermined range in the direction,
A valve body accommodating portion for accommodating the valve body is provided on the lower side of the valve seat, and the inlet is provided on the lower side of the valve body accommodating portion,
The valve main body has a main body member having a cylindrical portion provided with the plurality of outlets at its outer peripheral portion, and the inflow port, and an upper portion thereof is fixedly fitted to a lower portion of the cylindrical portion of the main body member Divided into an inlet member, and
The lower portion of the cylindrical portion of the body member and the valve seat, and the upper end portion of the inflow member define the valve body accommodating portion,
The upper end portion of the inflow member functions as a stopper that prevents the valve body from moving down from the lower surface of the valve seat by a predetermined distance or more.
The valve body has at least one open passage selectively opening the inlet and the outlets.
At least a first flow state in which the fluid flows from the inlet to the one of the outlets through the open passage by rotating the valve stem with the valve body, and the fluid from the inlet A flow passage switching valve characterized in that it is possible to selectively take a second flow state flowing to another one of the outlet through the open passage.   The valve shaft with a valve body is pushed up by the pressure of the fluid which flowed in to the inflow port, and, thereby, the upper surface of the valve body is pressed to the valve seat, characterized in that it is characterized by the above-mentioned. Flow control valve.   When the pressure at any one of the outlets increases by a predetermined pressure or more, the valve shaft with the valve body is pushed down to form a gap between the valve seat and the upper surface of the valve body, whereby the outlet The flow control valve according to claim 1, wherein the pressure on the side is released to the inflow side.   The flow according to claim 1, wherein the valve body is configured such that an upper surface other than the open passage can be in close contact with the valve seat so as to seal between the respective outlets in a watertight manner. Road switching valve.   The flow path switching valve according to claim 4, wherein the upper surface of the valve body other than the open passage is a flat smooth surface. A serration shaft portion is provided on the valve shaft, and a serration fitting hole is provided in the drive source, in which the serration shaft portion is axially slidably inserted.
An upper terrace surface provided above the upper end of the serration shaft and the serration shaft in the serration fitting hole in a state in which the valve body is in the lowermost position where the valve body contacts the upper end of the inflow member. The distance between them is longer than the distance between the highest position where the valve body is pressed against the valve seat and the lowest position where the valve body abuts on the upper end of the inflow member. Flow control valve. The drive source is provided with a fitting hole in which the upper end portion of the valve stem is slidably fitted in the axial direction and the upper surface is closed,
In a state in which the valve body is in the lowermost position where the valve body abuts on the upper end of the inflow member, a distance between the upper end of the valve stem and the upper surface of the fitting hole is the valve The flow path switching valve according to claim 1, characterized in that it is longer than the distance from the highest position to be pressed against the seat to the lowest position to contact the upper end of the inflow member.

Images