CN211523395U - Backflow-preventing drain valve structure - Google Patents

Abstract

The utility model discloses a backflow-preventing drain valve structure, which comprises a valve body and a base, wherein the valve body is movably provided with a valve core component and a starting component, the valve core component is in linkage fit with the starting component, the base is provided with a water outlet, and the starting component is driven to drive the valve core component to open the water outlet for draining; the drainage valve also comprises a limiting unit, and when the drainage valve is in a non-drainage state, the limiting unit enables the valve core assembly to be limited at a position for closing the drainage outlet; when the starting assembly is driven to drain water, the limiting unit releases the limiting on the valve core assembly so that the water outlet can be opened by the valve core assembly; therefore, even if the backflow water exerts upward thrust on the valve core assembly, the valve core assembly cannot move upwards, and dirt cannot flow back into the water tank; when the drainage valve switch is started, the starting assembly enables the limiting part to relieve limiting on the valve core assembly and starts the drainage valve to drain water, and the drainage valve switch is simple in structure and stable in performance.

Description

Backflow-preventing drain valve structure

Technical Field

The utility model relates to a drain valve structure of anti-backflow.

Background

In a toilet flushing device, a toggle or button switch on a water tank is generally operated to open a drain valve in the water tank to open a drain, so that water in the water tank in the toilet is discharged into the toilet through a drain port of the drain valve to flush waste in the toilet into a sewage pipe.

Most toilet tanks are now made lower for aesthetic and space saving purposes. The phenomenon of sewage pipeline blockage sometimes appears in the closestool use, especially for the closestool of low water tank, the phenomenon of blockage appears more easily. After the closestool is blocked, when the closestool dredging tool is used, impurities and dirt in the water storage bay can easily flow back to the water tank of the closestool, so that water in the water tank is polluted.

SUMMERY OF THE UTILITY MODEL

The utility model provides a backflow-proof drain valve structure for solving the problems, which solves the hidden danger of sewage backflow in the toilet water channel by arranging a backflow-proof limiting unit; in particular to solve the hidden trouble of sewage backflow when dredging the water channel of the toilet under the condition of toilet blockage of a low water tank. The structure is simple, reliable, easy to realize and obvious in effect.

In order to achieve the above object, the utility model adopts the following technical scheme:

the drain valve structure capable of preventing backflow comprises a valve body (10) and a base (20), wherein the valve body (10) is movably provided with a valve core assembly (30) and a starting assembly (40), the valve core assembly (30) is in linkage fit with the starting assembly (40), the base (20) is provided with a water outlet (23), and the starting assembly (40) is driven to drive the valve core assembly (30) to open the water outlet (23) for draining water; the drainage valve further comprises a limiting unit, and when the drainage valve is in a non-drainage state, the limiting unit enables the valve core assembly (30) to be limited at a position for closing the drainage outlet (23); when the starting assembly (40) is driven to drain water, the limiting unit releases the limiting on the valve core assembly (30) so that the valve core assembly (30) can open the drainage outlet (23).

Preferably, the limiting unit comprises a limiting part (50), the limiting part (50) can move between a limiting position and a yielding position, the limiting part (50) limits the valve core assembly (30) when the limiting position is reached, and the limiting part (50) yields the valve core assembly (30) when the yielding position is reached.

Preferably, the limiting member (50) is driven by the valve core assembly (30) or the starting assembly (40) to move from the limiting position to the abdicating position; locating part (50) by under the effect that resets by the position of stepping down moves to limiting position, it adopts balancing weight (61) or elasticity piece that resets to reset, perhaps, locating part (50) are in under the drive of start-up subassembly (40) by the position of stepping down moves to limiting position.

Preferably, the limiting part (50) moves between the limiting position and the abdicating position through rotation or sliding; the limiting piece (50) is movably arranged on the valve body (10), or the limiting piece (50) is movably arranged on the valve core assembly (30).

Preferably, the limiting unit further comprises a swinging block (70) which is swingably connected to the valve body (10), the starting assembly (40) is linked to the valve core assembly (30) through the swinging block (70), the swinging block (70) is in butt fit with the limiting member (50) to limit the limiting member (50) at the limiting position, when the starting assembly (40) drives the swinging block (70) to link with the valve core assembly (30), the swinging block (70) loses butt with the limiting member (50) to yield the limiting member (50), and the valve core assembly (30) can drive the limiting member (50) to move from the limiting position to the yielding position; or, when the starting assembly (40) drives the swinging block (70) to be linked with the valve core assembly (30), the swinging block (70) drives the limiting part (50) to move from the limiting position to the yielding position.

Preferably, the limiting member (50) can be attached to the valve body (10) in a swinging mode, the valve core assembly (30) is provided with a boss (311), and after the swinging block (70) gives way to the limiting member (50), the limiting member (50) gives way in an upward swinging mode under the thrust action of the boss (311).

Preferably, the valve core assembly (30) comprises a valve rod (31) and a sealing disc (32), and the sealing disc (32) is fixedly arranged at the bottom of the valve rod (31) and is matched with the water outlet (23) in an opening and closing manner; the valve rod (31) is provided with the boss (311), and the limiting piece (50) is provided with a limiting part (52) which is in butt fit with the boss (311).

Preferably, swing piece (70) with be equipped with linkage inclined plane (73) on one of the two of locating part (50), swing piece (70) with be equipped with traveller (53) on another of the two of locating part (50), swing piece (70) pass through linkage inclined plane (73) with the sliding fit of traveller (53) is in order to drive locating part (50) by limiting position activity extremely the position of stepping down.

Preferably, the limiting unit comprises a swinging block (70) which is installed on the valve body (10) in a swinging mode, the swinging block (70) is linked with the valve core assembly (30), the limiting member (50) is fixed on the swinging block (70), and a swinging axis (74) of the swinging block (70) is located right above a position where the valve core assembly (30) is abutted to the limiting member (50).

Preferably, during the opening process of the starting assembly (40), a section of idle stroke L is provided before the valve core assembly (30) is linked; in the movement process of the idle stroke L of the starting assembly (40), the limiting unit releases the limiting on the valve core assembly (30), and the starting assembly (40) moves the idle stroke L and then drives the valve core assembly (30).

Preferably, the base (20) is further provided with an overflow port (21) communicated with the water outlet (23), an overflow port baffle (22) capable of being opened in a single direction is arranged at the overflow port (21), the overflow port baffle (22) is opened under the pressure of overflow water when the water tank overflows, or the overflow port (21) is closed by the baffle (22) when water at the water outlet (23) flows backwards.

The utility model has the advantages that:

(1) by adding the limiting unit on the drain valve, when the drain valve is not started, the limiting unit enables the valve core assembly to be limited at the position for closing the drain outlet, so that even if the backflow water exerts upward thrust on the valve core assembly, the valve core assembly cannot move upwards, and dirt cannot flow back into the water tank; when the starting assembly is driven to drain, the limiting unit relieves the limiting on the valve core assembly so that the valve core assembly can open the water outlet to start the drain valve to drain, and the water draining device is simple in structure, stable in performance and reliable in function;

(2) the linkage fit of the starting assembly and the limiting part of the utility model drives the limiting part through the swinging block, so that the limiting part moves from the limiting position to the abdicating position through rotation or sliding, and the control is more flexible;

(3) the valve core assembly and the limiting part of the utility model are in linkage fit, the boss is arranged on the valve core assembly, and the limiting part is driven by the boss to move from the limiting position to the abdicating position, so that the structure is more reliable;

(4) the utility model discloses an in-process is opened to the start-up subassembly, is linking one section idle stroke has before the case subassembly for before case subassembly upward movement, spacing unit is relieved spacingly to the case subassembly, thereby guarantees that the action is smooth and easy.

Drawings

The accompanying drawings, which are described herein, serve to provide a further understanding of the invention and constitute a part of this specification, and the exemplary embodiments and descriptions thereof are provided for explaining the invention without unduly limiting it. In the drawings:

fig. 1 is a perspective view of a backflow prevention drain valve structure according to a first embodiment of the present invention;

fig. 2 is a sectional view of a backflow prevention drain valve structure according to a first embodiment of the present invention;

fig. 3 is an exploded view of a backflow prevention drain valve structure according to a first embodiment of the present invention;

fig. 4 is a cross-sectional view of an initial state of the backflow-preventing drain valve structure according to the first embodiment of the present invention (a state where the drain valve is not opened to drain, and the swing block limits the limiting member at a limiting position);

fig. 5 is a sectional view showing a drainage state of the backflow prevention drain valve structure according to the first embodiment of the present invention (a state where the drain valve is opened to drain water, and the swing block swings open to give way to the stopper);

fig. 6 is a cross-sectional view of an initial state of a backflow prevention drain valve structure according to a second embodiment of the present invention (a state where the drain valve is not opened to drain, and the swing block limits the limiting member at a limiting position);

fig. 7 is a sectional view showing a drainage state of the backflow prevention drain valve structure according to the second embodiment of the present invention (a state where the drain valve is opened to drain water, and the swing block drives the stopper to rotate to the receding position);

fig. 8 is an exploded view of a backflow prevention drain valve structure according to a third embodiment of the present invention;

fig. 9 is a sectional view of an initial state of a backflow prevention drain valve structure according to a third embodiment of the present invention (a state where the drain valve is not opened to drain, and the position limiting member is at a position limiting position);

fig. 10 is a sectional view showing a drainage state of a backflow prevention drain valve structure according to a third embodiment of the present invention (a state where a stopper is released from a stopper and starts to be actuated);

fig. 11 is a sectional view showing a drainage state of a backflow prevention drain valve structure according to a third embodiment of the present invention (a state where the drain valve is opened to drain water, and the stopper is at a position of abduction);

in the figure:

10-a valve body;

20-a base; 21-an overflow port; 22-overflow baffle; 23-a water outlet;

30-a spool assembly; 31-a valve stem; 311-boss; 32-sealing disk; 33-a floating barrel; 331-a swing rod;

40-a starting assembly; 41-a wire rope assembly; 411-fastener;

50-a limit piece; 51-abutted portions; 52-a limiting part; 53-a traveler;

a 60-C shaped snap ring; 61-a counterweight or elastic return member;

70-a swing block; 71-an abutment; 72-lifting the rod; 73-linkage slope; 74-axis of oscillation.

Detailed Description

In order to make the technical problem, technical solution and advantageous effects to be solved by the present invention clearer and more obvious, the following description of the present invention with reference to the accompanying drawings and embodiments is provided for further details. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.

First embodiment

As shown in fig. 1 to fig. 5, the backflow-preventing drain valve structure of the present embodiment includes a valve body 10 and a base 20, the valve body 10 is movably provided with a valve core assembly 30 and a starting assembly 40, the valve core assembly 30 is in linkage fit with the starting assembly 40, the base 20 is provided with a drain port 23, and the starting assembly 40 is driven to drive the valve core assembly 30 to open the drain port 23 for draining water; the valve core assembly 30 is limited at a position for closing the water outlet 23 by the limiting unit when the drain valve is in a non-drainage state; when the starting assembly 40 is driven to drain water, the limiting unit releases the limiting on the valve core assembly 30 so that the valve core assembly 30 can open the drain port 23.

In this embodiment, the limiting unit includes a limiting member 50 and a swinging block 70, and the limiting member 50 is matched with the valve core assembly 30. The limiting part 50 can move between a limiting position and a yielding position, during the limiting position, the limiting part 50 limits the valve core assembly 30, and during the yielding position, the limiting part 50 yields the valve core assembly 30. When the drain valve is in a non-drainage state, the limiting member 50 limits and cooperates with the valve core assembly 30, and the swinging block 70 abuts against the limiting member 50 so that the limiting member 50 is kept at a limiting position and cannot move to a yielding position. When the starting assembly 40 is driven to drain water, the starting assembly 40 drives the swinging block 70 to give way to the limiting piece 50, so that the limiting piece 50 relieves the limiting on the valve core assembly 30, and the limiting piece 50 moves from the limiting position to the giving way position under the driving of the valve core assembly 30; or, when the starting assembly 40 is driven to drain water, the starting assembly 40 drives the swing block 70, and the swing block 70 further drives the limiting member 50 to move from the limiting position to the yielding position, so that the limiting member 50 relieves the limiting on the valve core assembly 30. That is to say, the limiting member 50 can be selectively driven by the valve core assembly 30 or the actuating assembly 40 to move from the limiting position to the receding position.

The limiting member 50 can be reset from the abdicating position to the limiting position by manual reset or automatic reset. For example, the limiting member 50 moves from the abdicating position to the limiting position under the action of the resetting member, or the limiting member 50 moves from the abdicating position to the limiting position under the driving of the starting assembly 40, so as to achieve automatic resetting. As shown in fig. 3, in the present embodiment, the resetting member resets by using a weight block 61, the weight block 61 is disposed on a C-shaped snap ring 60, and the C-shaped snap ring 60 is snap-fitted with the limiting member 50 to rotatably mount the limiting member 50 on the valve body 10. In other embodiments, the reset element may also be an elastic reset element.

In other embodiments, the limiting member 50 may also be slidably attached to the valve body 10, that is, the limiting member 50 may move between the limiting position and the yielding position by rotating or sliding;

the swing block 70 is swing-mounted on the valve body 10, the starting assembly 40 is linked to the valve core assembly 30 through the swing block 70, the swing block 70 is abutted against and matched with the limiting member 50 to limit the limiting member 50 at the limiting position, when the starting assembly 40 drives the swing block 70 to link the valve core assembly 30, the swing block 70 is not abutted against the limiting member 50 to abdicate the limiting member 50, so that the valve core assembly 30 can drive the limiting member 50 to move from the limiting position to the abdicating position;

as shown in fig. 1 and 2, the starting assembly 40 includes a wire rope assembly 41 and a buckle 411 disposed on the valve body 10, one end of the wire rope assembly 41 is in linkage fit with the drain switch assembly, a rope sleeve of the wire rope at the other end is fixedly attached to the buckle 411 of the valve body 10, and the wire rope at the other end passes through the buckle 411 and extends into the valve body 10 to be in linkage fit with the swing block 70. In the state of not draining water, the swinging block 70 is in abutting fit with the limiting member 50; the swing block 70 is provided with an abutting portion 71, the stopper 50 is provided with an abutted portion 51, and when the stopper 50 is at the stopper position, the abutting portion 71 of the swing block 70 abuts against the abutted portion 51 of the stopper 50.

As shown in fig. 3, the valve core assembly 30 includes a valve rod 31 and a sealing disc 32, and the sealing disc 32 is fixedly arranged at the bottom of the valve rod 31 and is in open-close fit with the water outlet 23; the limiting member 50 can be attached to the valve body 10 in a swinging manner, the valve core assembly 30 is provided with a boss 311, and after the swinging block 70 gives way to the limiting member 50, the limiting member 50 swings upwards under the thrust action of the boss 311 to give way. In this embodiment, the boss 311 is disposed on the valve rod 31, and the limiting member 50 is provided with a limiting portion 52 abutting against and matching with the boss 311. The valve body 10 is further provided with a floating barrel 33, during water drainage, the floating barrel 33 hooks the valve rod 31 through a swing rod 331, so that the water outlet 23 is kept opened by the valve core assembly 30, and when the water level in the water tank drops to cause the floating barrel 33 to fall, the floating barrel 33 drives the swing rod 331 to swing open so that the swing rod 331 is separated from the valve rod 31, so that the water outlet 23 is closed by the valve core assembly 30 when the water level in the water tank falls.

As shown in fig. 3, in this embodiment, the valve body 10 includes an upper body and a lower isolation plate, the upper body and the lower isolation plate are fixedly connected to each other, the upper body and the lower isolation plate are respectively provided with a guide mechanism for guiding the valve core assembly 30, the buckle 411 of the wire rope assembly 41 is disposed on the upper body, and the swing block 70 is rotatably connected to the lower isolation plate.

As shown in fig. 2, 4 and 5, the base 20 is further provided with an overflow port 21 communicated with the water outlet 23, an overflow port baffle 22 capable of opening in one direction is arranged at the overflow port 21, when the water tank overflows, the overflow port baffle 22 opens under the pressure of overflow water, or when the water at the water outlet 23 flows backwards, the overflow port 21 is closed by the baffle 22.

In this embodiment, in the starting process of the starting assembly 40, a section of idle stroke L is provided before the valve core assembly 30 is linked; in the movement process of the idle stroke L of the starting assembly 40, the limiting unit relieves the limiting on the valve core assembly 30, and the starting assembly 40 moves the idle stroke L and then gives way to the limiting piece 50.

The working principle of the embodiment is briefly described as follows:

as shown in fig. 4, in the initial state, the sealing disc 32 of the valve core assembly 30 closes the water outlet 23, and the overflow port baffle 22 closes the overflow port 21; the abutting part 71 of the swinging block 70 abuts against the abutted part 51 of the stopper 50, so that the stopper 50 cannot rotate counterclockwise;

when sewage and dirt flow back, the valve core assembly 30 is jacked up, and because the valve core assembly 30 is jacked by the limiting part 50, the abutting part 71 abuts against the abutted part 51, so that the limiting part 50 cannot swing open, the limiting part 52 on the limiting part 50 limits the upward movement of the valve core assembly 30, the valve core assembly 30 cannot move upward, the water outlet 23 cannot be opened, and the dirt cannot flow back to the water tank.

As shown in fig. 5, when the drain switch (not shown) is activated, the wire rope assembly 41 pulls the swing block 70 to swing, the swing block 70 swings open, the abutting portion 71 leaves the abutted portion 51 to release the limit on the limit-limiting member 50, the swing block 70 loses the limit on the limit-limiting member 50, and the limit-limiting member 50 rotates counterclockwise under the pushing of the valve core assembly 30 to release the limit on the valve core assembly 30; the oscillating block 70 is interlocked with the upward movement of the valve core assembly 30, and the sealing disc 32 of the valve core assembly 30 opens the drain opening 23 for draining.

When the water in the water tank overflows, the overflow port baffle 22 forms a one-way valve, and the water flow impacts the overflow port baffle 22 to enable the baffle to rotate to open the overflow port 21; when not overflowing, the overflow port shutter 22 closes the overflow port 21 so that the filth cannot flow back.

Second embodiment

As shown in fig. 6 and 7, the main difference between the present embodiment and the first embodiment is that: in this embodiment, when the starting component 40 drives the swing block 70 to link the valve core component 30, the swing block 70 drives the limiting member 50 to move to the abdicating position from the limiting position, specifically, the swing block 70 drives the limiting member 50 to swing and abdicating downwards when swinging. That is, the limiting member 50 of the first embodiment swings in such a way that after the swing block 70 moves away, the limiting member 50 can swing open counterclockwise under the driving of the upward movement of the valve core assembly 30; the swinging manner of the limiting member 50 of the present embodiment is that the swinging block 70 drives the limiting member 50 to rotate clockwise for yielding when swinging, so that the valve core assembly 30 can move upward.

In this embodiment, the limiting unit further includes a swinging block 70 which is swingably attached to the valve body 10, and the swinging block 70 is slidably engaged with the limiting member 50; one of the swing block 70 and the limiting member 50 is provided with a linkage inclined plane 73, and the other of the swing block 70 and the limiting member 50 is provided with a sliding column 53; in this embodiment, the swing block 70 is provided with a linkage inclined surface 73, the limiting member 50 is provided with a sliding column 53, and the swing block 70 drives the limiting member 50 to move to the abdicating position from the limiting position through the sliding fit between the linkage inclined surface 73 and the sliding column 53.

In this embodiment, in the starting process of the starting assembly 40, a section of idle stroke L is provided before the valve core assembly 30 is linked; in the movement process of the idle stroke L of the starting assembly 40, the limiting unit releases the limiting on the valve core assembly 30, and the starting assembly 40 moves the idle stroke L and then drives the valve core assembly 30.

The operating principle of this embodiment differs from that of the first embodiment mainly in that:

as shown in fig. 6, in the initial state, the linking inclined surface 73 of the swing block 70 of the present embodiment abuts against the sliding post 53 of the limiting member 50, so that the limiting member 50 cannot rotate clockwise; as shown in fig. 7, in the state of opening the drain valve, the limiting member 50 slides and swings open under the action of the linkage inclined surface 73 and the sliding column 53 to give way for the upward movement of the valve core assembly 30, and the sealing disc 32 of the valve core assembly 30 opens the drain opening 23 to drain water.

The rest of the structure and the operation principle of this embodiment are similar to those of the first embodiment, and are not described herein again.

Third embodiment

As shown in fig. 8 to 11, the main difference between the present embodiment and the first embodiment is: in this embodiment, the starting assembly 40 includes a key, the limiting unit includes a limiting member 50 and a swinging block 70 that is swingably attached to the valve body 10, the key is linked with the swinging block 70, the swinging block 70 is linked with the valve core assembly 30, the limiting member 50 is fixed to the swinging block 70, and a swinging axis 74 of the swinging block 70 is located right above a position where the valve core assembly 30 abuts against the limiting member 50. The boss 311 provided on the valve core assembly 30 abuts against the limiting member 50, and the swing axis 74 of the swing block 70 is located right above the position where the boss 311 abuts against the limiting member 50.

The operating principle of this embodiment differs from that of the first embodiment mainly in that:

as shown in fig. 9, in the initial state, the limiting member 50 on the swing block 70 of the present embodiment abuts against the boss 311 on the valve core assembly 30, so that the limiting member 50 cannot rotate clockwise; as shown in fig. 10 to 11, in the state where the drain valve is opened, the limiting member 50 swings clockwise along with the swing of the swing block 70 to give way to the upward movement of the valve core assembly 30, and the sealing disc 32 of the valve core assembly 30 opens the drain port 23 to drain water.

The rest of the structure and the operation principle of this embodiment are similar to those of the first embodiment, and are not described herein again.

It should be noted that, in other embodiments, the limiting member may be movably disposed on the valve core assembly 30, and the limiting member on the valve core assembly 30 abuts against the valve body 10 when water is not drained, so that the valve core assembly 30 is limited at a position for closing the water outlet 23; when drive start-up subassembly 40 carries out the drainage, start-up subassembly 40 drives the locating part by the activity of limiting position to the position of stepping down, perhaps, start-up subassembly 40 steps down to the locating part, and the locating part can be moved to the position of stepping down by limiting position under the drive of case subassembly 30 to make the locating part remove the spacing so that to case subassembly 30 can be opened outlet 23 also can realize like this the utility model aims at.

While the foregoing description shows and describes the preferred embodiments of the present invention, it is to be understood that the invention is not limited to the forms disclosed herein, but is not intended to be exhaustive or to exclude other embodiments and may be used in various other combinations, modifications, and environments and is capable of changes within the scope of the inventive concept as expressed herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. But that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention, which is to be limited only by the claims appended hereto.

Claims (11)

1. The drain valve structure capable of preventing backflow comprises a valve body (10) and a base (20), wherein the valve body (10) is movably provided with a valve core assembly (30) and a starting assembly (40), the valve core assembly (30) is in linkage fit with the starting assembly (40), the base (20) is provided with a water outlet (23), and the starting assembly (40) is driven to drive the valve core assembly (30) to open the water outlet (23) for draining water; the drainage valve is characterized by further comprising a limiting unit, wherein when the drainage valve is in a non-drainage state, the limiting unit enables the valve core assembly (30) to be limited at a position for closing the drainage outlet (23); when the starting assembly (40) is driven to drain water, the limiting unit releases the limiting on the valve core assembly (30) so that the valve core assembly (30) can open the drainage outlet (23).

2. The drain valve structure against backflow according to claim 1, wherein: the limiting unit comprises a limiting part (50), the limiting part (50) can move between a limiting position and a yielding position, the limiting part (50) is used for limiting the valve core assembly (30) during the limiting position, and the limiting part (50) is used for yielding the valve core assembly (30) during the yielding position.

3. The drain valve structure against backflow according to claim 2, wherein: the limiting piece (50) is driven by the valve core assembly (30) or the starting assembly (40) to move from the limiting position to the abdicating position; locating part (50) by under the effect that resets by the position of stepping down moves to limiting position, it adopts balancing weight (61) or elasticity piece that resets to reset, perhaps, locating part (50) are in under the drive of start-up subassembly (40) by the position of stepping down moves to limiting position.

4. The drain valve structure against backflow according to claim 2, wherein: the limiting piece (50) moves between the limiting position and the yielding position through rotation or sliding; the limiting piece (50) is movably arranged on the valve body (10), or the limiting piece (50) is movably arranged on the valve core assembly (30).

5. The drain valve structure against backflow according to claim 2, wherein: the limiting unit further comprises a swinging block (70) which is arranged on the valve body (10) in a swinging mode, the starting assembly (40) is linked with the valve core assembly (30) through the swinging block (70), the swinging block (70) is in butt fit with the limiting piece (50) to limit the limiting piece (50) at the limiting position, when the starting assembly (40) drives the swinging block (70) to be linked with the valve core assembly (30), the swinging block (70) is not in butt fit with the limiting piece (50) to yield the limiting piece (50), and the valve core assembly (30) can drive the limiting piece (50) to move from the limiting position to the yielding position; or, when the starting assembly (40) drives the swinging block (70) to be linked with the valve core assembly (30), the swinging block (70) drives the limiting part (50) to move from the limiting position to the yielding position.

6. The drain valve structure against backflow according to claim 5, wherein: the limiting piece (50) can be installed on the valve body (10) in a swinging mode, the valve core assembly (30) is provided with a boss (311), the swinging block (70) moves back to the limiting piece (50), and the limiting piece (50) moves up under the thrust action of the boss (311) in a swinging mode.

7. The drain valve structure against backflow according to claim 6, wherein: the valve core assembly (30) comprises a valve rod (31) and a sealing disc (32), and the sealing disc (32) is fixedly arranged at the bottom of the valve rod (31) and is matched with the water outlet (23) in an opening and closing manner; the valve rod (31) is provided with the boss (311), and the limiting piece (50) is provided with a limiting part (52) which is in butt fit with the boss (311).

8. The drain valve structure against backflow according to claim 5, wherein: swing piece (70) with be equipped with linkage inclined plane (73) on one of the two of locating part (50), swing piece (70) with be equipped with traveller (53) on another of the two of locating part (50), swing piece (70) pass through linkage inclined plane (73) with the sliding fit of traveller (53) is in order to drive locating part (50) by limiting position activity extremely give way the position.

9. The drain valve structure against backflow according to claim 4, wherein: the limiting unit further comprises a swinging block (70) which is arranged on the valve body (10) in a swinging mode, the swinging block (70) is linked with the valve core assembly (30), the limiting member (50) is fixed on the swinging block (70), and a swinging axis (74) of the swinging block (70) is located right above the position where the valve core assembly (30) is abutted to the limiting member (50).

10. The drain valve structure against backflow according to claim 1, wherein: in the starting process of the starting assembly (40), a section of idle stroke L is arranged before the valve core assembly (30) is linked; in the movement process of the idle stroke L of the starting assembly (40), the limiting unit releases the limiting on the valve core assembly (30), and the starting assembly (40) moves the idle stroke L and then drives the valve core assembly (30).

11. The drain valve structure against backflow according to claim 1, wherein: the base (20) still be equipped with overflow mouth (21) of outlet (23) intercommunication, overflow mouth (21) department is equipped with overflow mouth baffle (22) that can one-way open, during the water tank overflow, overflow mouth baffle (22) are opened under the pressure of overflow water, perhaps, when the water refluence of outlet (23) department, baffle (22) are closed overflow mouth (21).

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