CN209943608U - Vent valve for urea box - Google Patents

Abstract

The utility model discloses a vent valve for a urea box, which comprises a valve cavity, wherein the valve cavity is provided with a first opening communicated with the outside of the urea box and a second opening communicated with the inside of the urea box; the valve cavity is internally provided with a first vent hole and a second vent hole; the first vent hole is provided with a first floating assembly for selectively opening or sealing the first vent hole; a second floating assembly is arranged at the second vent hole, when the urea box is horizontally placed, the second vent hole is normally opened, and when the urea box inclines or turns over, the second vent hole is sealed; so, it utilizes for the urea case breather valve to replace traditional breather valve and blast pipe, has reduced part quantity, has reduced material cost, has reduced mould cost and assembly cost, especially, with the help of the setting of subassembly that floats, ensures that the urea case homoenergetic is nimble to keep the air pressure balance in the urea case under various states, and, can not leak urea when slope and upset urea case to, effectively improve market competition.

Description

Vent valve for urea box

Technical Field

The utility model belongs to the technical field of the urea case technique and specifically relates to indicate a breather valve for urea case.

Background

In the prior art, the urea tank is usually equipped with a ventilation valve and an exhaust pipe, however, the following drawbacks are common: high cost of die and assembly, multiple parts, complex structure, etc.

Therefore, in the present invention, the applicant has studied a new technical solution elaborately to solve the above-mentioned problems.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model discloses to the disappearance that prior art exists, its main objective provides a breather valve for urea case, it utilizes the breather valve for the urea case to replace traditional breather valve and blast pipe, part quantity has been reduced, material cost has been reduced, mould cost and assembly cost have been reduced, especially, with the help of the setting of subassembly that floats, ensure that the urea case homoenergetic is nimble to keep the air pressure balance in the urea case under various states, and, can not leak urea during slope and upset urea case to, effectively improve market competition.

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

a vent valve for a urea box comprises a valve cavity, a valve body and a valve seat, wherein the valve cavity is provided with a first opening communicated with the outside of the urea box and a second opening communicated with the inside of the urea box; a first vent hole and a second vent hole are arranged in the valve cavity; the first opening, the first vent hole and the second opening are sequentially communicated to form a first vent route, and the first opening, the second vent hole and the second opening are sequentially communicated to form a second vent route;

a first floating assembly is arranged at the first vent hole; the first floating assembly comprises a first floating piece and a first reset elastic piece for providing reset acting force of the first floating piece towards the first vent hole; the first floating piece can be arranged in an up-and-down displacement mode to selectively open or seal the first vent hole;

a second floating assembly is arranged at the second vent hole; the second floating assembly comprises a second floating piece and a second reset elastic piece for providing reset acting force of the second floating piece towards the second ventilation hole; when the urea box is horizontally placed, the second floating piece is far away from the second vent hole to open the second vent hole, and when the urea box inclines beyond a set angle or turns over, the second floating piece moves towards the second vent hole to seal the second vent hole.

As a preferred scheme, the first and second ventilation holes are respectively disposed on a fixing base, the fixing base is provided with an upper cover, the first opening is formed between the upper cover and the fixing base, and the second opening is formed on the fixing base.

Preferably, the upper cover is detachably connected to the fixing seat.

Preferably, an external thread for detachably assembling the vent valve on the urea tank is formed outside the fixing seat.

Preferably, the first vent hole and/or the second vent hole are in a tapered structure with a small top and a big bottom; the upper end of the first float member and/or the second float member has a tapered mating portion.

Preferably, the tapered structure is formed on a vent cover, and the vent cover is assembled on the fixed seat.

As a preferred scheme, a first accommodating cavity and a second accommodating cavity are arranged in the fixed seat; the first floating assembly is arranged in the first accommodating cavity, and the second floating assembly is arranged in the second accommodating cavity; the upper end of the first accommodating cavity is communicated with a first vent hole, a first communication hole communicated with a second opening is formed in the lower section area of the first accommodating cavity, and a second communication hole communicated with the second opening is formed in the lower section area of the second accommodating cavity; the second communication hole is positioned above the first communication hole;

the first communicating hole and the second communicating hole are respectively communicated with the second opening, or the second communicating hole is communicated with the second opening through the first accommodating cavity and the first communicating hole.

As a preferable scheme, the lower end of the fixing seat is detachably assembled with a lower cover.

As a preferable scheme, the lower cover is provided with a yielding hole, and the first floating piece penetrates through the yielding hole and extends out of the lower cover downwards; the periphery of the upper section of the first floating piece is convexly provided with a flange, the upper end of the first resetting elastic piece acts on the flange, and the lower end of the first resetting elastic piece acts on the lower cover.

As a preferable scheme, the second floating member is a floating ball, the second return elastic member is a compression spring, the ball diameter of the floating ball is larger than the outer diameter of the compression spring, the floating ball is placed at the upper end of the compression spring, and the lower end of the floating ball extends into the compression spring.

Compared with the prior art, the utility model obvious advantage and beneficial effect have, particularly, can know by above-mentioned technical scheme:

the urea box has the advantages that the conventional vent valve and exhaust pipe are replaced by the vent valve for the urea box, so that the number of parts is reduced, the material cost is reduced, the mold cost and the assembly cost are reduced, particularly, the arrangement of the floating assembly is used for ensuring that the air pressure in the urea box can be flexibly kept balanced in various states, and urea cannot leak when the urea box is inclined or turned over, so that the market competitiveness is effectively improved;

secondly, the first communicating hole is positioned above the second communicating hole, the first floating part can be subjected to the upward buoyancy effect of urea in the urea filling process and when the urea is filled to a set volume (or height), and the second floating part cannot be subjected to the upward buoyancy effect of urea, so that the second communicating hole is always in an open state, and the balance of the air pressure inside and outside the urea box is kept;

the whole vent valve can be connected to the urea box in a threaded manner, the vent valve can be conveniently disassembled and assembled on the urea box, the upper cover and the fixing seat are detachably assembled, the lower cover and the fixing seat are detachably assembled, the parts are conveniently disassembled and assembled, and the parts are convenient to clean, maintain, overhaul and replace.

To illustrate the structural features and functions of the present invention more clearly, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

Drawings

FIG. 1 is an exploded view of a first embodiment of the present invention;

fig. 2 is a diagram showing a first state of a first embodiment of the present invention (a horizontal state of a urea tank, and before urea is filled or when urea is not filled to a set height);

FIG. 3 is a diagram of a second state of a first embodiment of the present invention (urea is filled to a set height);

FIG. 4 is a diagram showing a third state (urea tank turning state) of the first embodiment of the present invention;

FIG. 5 is an exploded view of a second embodiment of the present invention;

fig. 6 is a diagram showing a first state of a second embodiment of the present invention (the urea tank is in a horizontal state, and urea is not filled before or at a predetermined height);

FIG. 7 is a diagram showing a second state of the second embodiment of the present invention (when urea is injected to a set height);

fig. 8 is a third state diagram (urea tank turning state) of the second embodiment of the present invention.

The attached drawings indicate the following:

101. a first vent hole 102 and a second vent hole

103. First floating member 104, first elastic return member

105. Second floating member 106, second restoring elastic member

107. Fixing seat 108 and upper cover

109. The first vent cover 110 and the second vent cover

111. The first accommodating cavity 112 and the second accommodating cavity

113. First and second communication holes 114 and 114

115. Lower cover 116, stuck point

117. Fastening hole 118 and sealing gasket

201. Upper cover 202 and fixing seat

203. Lower cover 204, first float member

205. First elastic reset element 206 and second floating element

207. First restoring elastic piece 208 and second communicating hole

209. The first accommodating cavity 210 and the first connecting hole

211. Float rod 212, float bowl

213. A first vent hole 214, a second vent hole.

Detailed Description

Fig. 1 to 8 show specific structures of a first embodiment and a second embodiment of the present invention.

First, please refer to fig. 1 to 4, which mainly take a first embodiment as an example for description:

a vent valve for a urea box comprises a valve cavity, a valve body and a valve seat, wherein the valve cavity is provided with a first opening communicated with the outside of the urea box and a second opening communicated with the inside of the urea box; a first vent hole 101 and a second vent hole 102 are arranged in the valve cavity; the first opening, the first vent hole 101 and the second opening sequentially penetrate to form a first vent route, and the first opening, the second vent hole 102 and the second opening sequentially penetrate to form a second vent route; the valve cavity may be formed in the urea tank, or (but is not limited to) the valve cavity may be formed in the fixing seat 107 or other parts as shown in this embodiment.

A first floating assembly is arranged at the first vent hole 101; the first floating assembly comprises a first floating piece 103 and a first reset elastic piece 104 providing reset acting force of the first floating piece 103 towards the first vent hole 101; the first floating piece 103 can be arranged in an up-and-down displacement mode to selectively open or seal the first vent hole 101;

a second floating assembly is arranged at the second vent hole 102; the second floating assembly comprises a second floating piece 105 and a second reset elastic piece 106 which provides reset acting force of the second floating piece 105 towards the second ventilation hole 102; when the urea tank is horizontally placed, the second floating member 105 is away from the second ventilation hole 102 to open the second ventilation hole 102, and when the urea tank is inclined beyond a set angle or turned over, the second floating member 105 is displaced toward the second ventilation hole 102 to seal the second ventilation hole 102, wherein the set angle depends on the self-gravity of the second floating member 105 and the restoring force of the second restoring elastic member 106.

As shown in fig. 2, when the urea tank is in a horizontal state and urea is not filled into the bottom end of the first floating member 103, the first floating member 103 deforms the first return elastic member 104 under the action of gravity, at this time, the first floating member 103 does not seal the first vent hole 101, and the first vent hole 101 is in a normally open state; similarly, the second floating member 105 deforms the second elastic return member 106 under the action of gravity, at this time, the second floating member 105 does not seal the second vent hole 102, and the second vent hole 102 is in a normally open state; therefore, during this urea phase, the pressure inside and outside the urea tank is kept in equilibrium.

As shown in fig. 3, when urea is filled to a set height (or, when urea is filled to a set volume, the set height is higher than the bottom end of the first float member 103), the first float member 103 seals the first vent hole 101; from urea filling to the bottom of first floating member 103, until urea filling to the settlement height, this section filling in-process, first floating member 103 can receive urea buoyancy effect and upwards displacement, and when first floating member 103 upwards sealed first air vent 101 the one-time, the inside atmospheric pressure of urea case changes greatly to trigger the filling gun and jump the rifle and then realize spacing filling purpose. The second floating member 105 always deforms the second elastic return member 106 under its own weight, and the second ventilation hole 102 is normally open; in this embodiment, because the second floating member 105 is not subjected to the buoyancy of urea, in fact, it is only necessary to satisfy that the self gravity of the second floating member 105 is greater than the restoring acting force of the second restoring elastic member 106, and the self gravity of the second floating member 105 is greater than the sum of the restoring acting force of the second restoring elastic member 106 and the buoyancy of urea received by the second floating member 105, so that when the urea tank is in a horizontal state, the second floating member 105 does not seal the second vent hole 102, that is, the second vent hole 102 is always in a normally open state; therefore, the air pressure inside and outside the urea box is kept balanced during the filling process until the urea is filled to the set height;

therefore, the air pressure inside and outside the urea box is kept balanced in various states; in fact, since the second vent hole 102 is normally open when the urea tank is in a horizontal state, the urea tank can maintain the internal and external air pressure balance at least through the second vent hole 102, and the internal and external air pressure balance is maintained by both the first vent hole 101 and the second vent hole 102 before and during the urea filling process.

As shown in fig. 4, when the urea tank is in a reversed state, the first floating member 103 seals the first vent hole 101 under the action of the gravity of the first floating member 103 and the action of the first return elastic member 104; meanwhile, under the action of the gravity of the second floating member 105 and the action of the second elastic return member 106, the second floating member 105 seals the second vent hole 102; thus, the acting forces of the first and second elastic restoring members 104 and 106 enable the first and second floating members 103 and 105 to more stably seal the first and second ventilation holes 101 and 102, thereby effectively preventing urea from leaking out. Of course, the turning state is not limited to the up-down 180 degree turning shown in fig. 4, and also includes a non-horizontal state such as a tilting of the urea tank caused by a side-turning or other reasons, when the urea tank is in the non-horizontal state, the gravity component of the first floating member 103 in the direction opposite to the direction of the restoring force (upward direction) of the first restoring elastic member 104 is smaller than the gravity, so that the restoring force of the first restoring elastic member 104 plus the buoyancy of the urea is usually enough to counteract the gravity component to ensure that the first floating member 103 seals the first ventilation hole 101; similarly, when the urea tank is in a non-horizontal state, the component of the gravity force of the second floating member 105 in the direction opposite to the direction of the return force of the second return elastic member 106 (upward direction) is smaller than the gravity force, so when the urea tank is inclined beyond a set angle, the return force of the second return elastic member 106 is usually enough to counteract the component of the gravity force to ensure that the second floating member 105 seals the second vent hole 102, thereby preventing urea leakage.

Next, the main component structure of the present embodiment will be described in detail:

the first vent hole 101 and the second vent hole 102 are respectively disposed on a fixing seat 107, the fixing seat 107 is provided with an upper cover 108, the first opening is formed between the upper cover 108 and the fixing seat 107, and the second opening is formed on the fixing seat 107. Here, the upper cover 108 has a channel communicating with the first opening, the channel can communicate with the outside, and the upper cover 108 can be externally connected with a connector as required to communicate with the channel; the upper cover 108 is detachably connected to the fixing base 107, so that internal parts can be conveniently cleaned, maintained, repaired, replaced and the like. Preferably, the upper cover 108 is screwed to the upper end of the fixing base 107, where the upper cover 108 is provided with a first internal thread, and the upper end of the fixing base 107 is provided with a first external thread, and the first internal thread and the first external thread are adapted to form a connection location. The outside of fixing base 107 is formed with and supplies the detachable external screw thread (referring to the second external screw thread) of assembling on the urea case of breather valve, so, whole breather valve can threaded connection on the urea case, and when needing to dismantle, direct rotation is dismantled whole breather valve from the urea case.

The first vent hole 101 and/or the second vent hole 102 are in a tapered structure with a small top and a big bottom; the upper end of the first float member 103 and/or the second float member 105 has a conical matching portion to create a better sealing effect. Here, the tapered structure is formed on a vent cover, the vent cover is assembled on the fixing base 107, the vent cover includes a first vent cover 109 and a second vent cover 110, the first vent cover 109 and the second vent cover 110 are respectively assembled on the fixing base 107 to form the first vent 101 and the second vent 102, and the assembly method may adopt a fastening connection or other suitable assembly methods. Preferably, the first ventilation holes 101 are larger in size than the second ventilation holes 102.

A first accommodating cavity 111 and a second accommodating cavity 112 are arranged in the fixed seat 107; the first floating assembly is arranged in the first accommodating cavity 111, and the second floating assembly is arranged in the second accommodating cavity 112; the upper end of the first accommodating cavity 111 is communicated with the first vent hole 101, the lower section area of the first accommodating cavity 111 is provided with a first communication hole 113 communicated with the second opening, and the lower section area of the second accommodating cavity 112 is provided with a second communication hole 114 communicated with the second opening; the second communication hole 114 is located above the first communication hole 113, the first communication hole 113 and the second communication hole 114 are respectively communicated with the second openings, and by means of the fact that the second communication hole 114 is located above the first communication hole 113, when urea is filled in the process and urea is filled to a set volume (or height), the first floating piece 103 can be subjected to the upward buoyancy effect of urea, the second floating piece 105 cannot be subjected to the upward buoyancy effect of urea, the second communication hole 102 is ensured to be always in an open state, and the balance of the air pressure inside and outside the urea box is kept.

A lower cover 115 is detachably assembled at the lower end of the fixing seat 107, preferably, the lower cover 115 is assembled at the lower end of the fixing seat 107 in a buckling manner, a fastening point 116 is convexly arranged on the periphery of the lower cover 115, a fastening hole 117 is arranged at the lower end of the fixing seat 107, the lower cover 115 is upwards assembled at the lower end of the fixing seat 107, and the fastening point 116 is buckled in the fastening hole 117 to form positioning. The lower cover 115 is provided with a yielding hole, the first floating piece 103 penetrates through the yielding hole and extends downwards out of the lower cover 115 so as to obtain larger buoyancy, and more importantly, the length of the first floating piece 103 extending downwards out of the lower part of the lower cover 115 can be determined according to the actual application condition or the set volume, so that the purpose of limiting and filling is achieved; here, a flange is convexly provided on the periphery of the upper section of the first floating member 103, the upper end of the first restoring elastic member 104 acts on the flange, the lower end of the first restoring elastic member 104 acts on the lower cover 115, the first restoring elastic member 104 is a compression spring, the first restoring elastic member 104 is sleeved on the first floating member 103, the upper end of the first restoring elastic member 104 abuts against the limiting portion of the first floating member 103, and the lower end of the first restoring elastic member 104 abuts against the lower cover 115; the convex flange arranged on the periphery of the upper section of the first floating piece 103 in a protruding mode is matched with the first accommodating cavity 111 to form limiting guide, and the limiting guide of the first floating piece 103 is conducted through the yielding hole of the lower cover 115, so that the first floating piece 103 is prevented from moving left and right, and the stable movement of the first floating piece 103 is guaranteed.

And the second floating member 105 is a floating ball, the second return elastic member 106 is also a compression spring, the ball diameter of the floating ball is larger than the outer diameter of the compression spring, the floating ball is placed at the upper end of the compression spring, and the lower end of the floating ball extends into the compression spring.

And, as shown in fig. 1 and fig. 2, next, an assembling step of the vent valve of the present embodiment is described:

firstly, the first vent cover 109 is buckled and pressed downwards at the upper end of the fixed seat 107, and then the first floating assembly is arranged in the first accommodating cavity 111: the first elastic restoring member 104 is sleeved on the first floating member 103 (of course, the upper end of the first floating member 103 may be provided with a sealing gasket 118 as required), and then is installed into the first accommodating cavity 111 from above; then the lower cover 115 is buckled and pressed on the lower end of the fixed seat 107;

second, the second floating assembly is loaded into the second containing cavity 112: the second reset elastic piece 106 and the floating ball are sequentially arranged, and then the second vent hole cover 110 is buckled downwards;

thirdly, the upper cover 108 is screwed and connected to the upper end of the fixed seat 107;

the sequence of the first step and the second step can be changed according to the process requirement.

When the vent valve of the present embodiment needs to be disassembled:

firstly, rotationally detaching the whole vent valve from a urea box;

secondly, the upper cover 108 is rotatably disassembled from the upper end of the fixed seat 107; next, the second vent cover 110, the floating ball, and the second return spring 106 may be sequentially removed;

thirdly, the lower cover 115 is pressed, and the lower cover 115 is detached from the lower end of the fixed seat 107; next, the first floating member 103 and the first return elastic member 104 may be taken out;

in this way, the parts can be repaired, maintained, replaced, and cleaned, and the first vent cover 109 and the second vent cover 110 can be cleaned as needed or periodically.

Next, referring to fig. 5 to 8, a structure of a second embodiment is shown, which is basically the same as the main structure of the first embodiment, and includes an upper cover 201, a fixing base 202, a lower cover 203, a first floating member 204, a first elastic restoring member 205, a second floating member 206, a first elastic restoring member 207, and the like; the main difference lies in that:

one is as follows: the second communication hole 208 is communicated with the second opening through the first accommodating cavity 209 and the first communication hole 210;

the second is that: the first floating member 204 is designed to extend out of the lower cover from the smaller floating rod 211, and the larger floating barrel 212 is connected to the lower end of the floating rod 211 to increase the overall buoyancy of the urea solution to the floating rod 211 and lower the overall gravity center of the floating rod 211, so that the overall stable motion of the floating rod 211 is ensured; in the first embodiment, the first floating member 103 is a large hollow rod structure;

the third step is that: the tapered structure of the first vent hole 213 with a small top and a large bottom is directly formed on the fixing base 202, and of course, the tapered structures of the first vent hole and/or the second vent hole in the first and second embodiments can be directly formed on the fixing base or on the vent hole cover;

the fourth step is that: the upper end of the first floating member 201 is designed to be conical, while the upper end of the first floating member 103 in the first embodiment is designed to be truncated cone;

the fifth step is: the size of the first ventilation hole 213 is similar to that of the second ventilation hole 214, and in the first embodiment, the size of the first ventilation hole 101 is significantly larger than that of the second ventilation hole 102.

It should be noted that the technical solution of the present invention is not limited to the first and second embodiments, and the structure and assembly relationship of the components can be changed as required, and the main inventive spirit of the technical solution lies in: the two groups of floating assemblies form opening and closing control on the two vent holes as required, so that the urea box can flexibly keep air pressure balance in the urea box in various states, and urea cannot leak when the urea box is inclined and turned over.

To sum up, the utility model is mainly designed to replace the traditional vent valve and exhaust pipe with the vent valve by the urea box, thereby reducing the number of parts, reducing the material cost, reducing the mold cost and the assembly cost, and especially, by means of the arrangement of the floating assembly, ensuring that the urea box can flexibly keep the air pressure balance in the urea box under various states, and preventing urea leakage when the urea box is inclined and turned over, thereby effectively improving the market competitiveness; secondly, the first communicating hole is positioned above the second communicating hole, so that the first floating part can be subjected to the upward buoyancy action of urea in the urea filling process and when the urea is filled to a set volume (or height), and the second floating part cannot be subjected to the upward buoyancy action of urea, so that the second communicating hole is always in an open state, and the balance of the air pressure inside and outside the urea box is kept; and, whole breather valve can threaded connection on the urea case, and the dismouting of breather valve on the urea case of being convenient for is used to and, combines the detachable equipment of upper cover and fixing base, detachable equipment between lower cover and the fixing base for the dismouting is very convenient between the spare part, and the washing of being convenient for is maintained, is overhauld and is changed.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the technical scope of the present invention, so that any slight modifications, equivalent changes and modifications made by the technical spirit of the present invention to the above embodiments are all within the scope of the technical solution of the present invention.

Claims (10)

1. The utility model provides a breather valve for urea case which characterized in that: the valve cavity is provided with a first opening communicated with the outside of the urea box and a second opening communicated with the inside of the urea box; a first vent hole and a second vent hole are arranged in the valve cavity; the first opening, the first vent hole and the second opening are sequentially communicated to form a first vent route, and the first opening, the second vent hole and the second opening are sequentially communicated to form a second vent route;

a first floating assembly is arranged at the first vent hole; the first floating assembly comprises a first floating piece and a first reset elastic piece for providing reset acting force of the first floating piece towards the first vent hole; the first floating piece can be arranged in an up-and-down displacement mode to selectively open or seal the first vent hole;

a second floating assembly is arranged at the second vent hole; the second floating assembly comprises a second floating piece and a second reset elastic piece for providing reset acting force of the second floating piece towards the second ventilation hole; when the urea box is horizontally placed, the second floating piece is far away from the second vent hole to open the second vent hole, and when the urea box inclines beyond a set angle or turns over, the second floating piece moves towards the second vent hole to seal the second vent hole.

2. The vent valve for a urea tank as claimed in claim 1, wherein: the first vent hole and the second vent hole are respectively arranged on a fixed seat, the fixed seat is provided with an upper cover, the first opening is formed between the upper cover and the fixed seat, and the second opening is formed on the fixed seat.

3. The vent valve for a urea tank as claimed in claim 2, wherein: the upper cover is detachably connected to the fixed seat.

4. The vent valve for a urea tank as claimed in claim 2, wherein: and an external thread for detachably assembling the ventilation valve on the urea box is formed outside the fixed seat.

5. The vent valve for a urea tank as claimed in claim 2, wherein: the first vent hole and/or the second vent hole are in a tapered structure with a small upper part and a big lower part; the upper end of the first float member and/or the second float member has a tapered mating portion.

6. The vent valve for a urea tank as claimed in claim 5, wherein: the cone-shaped structure is formed on the vent hole cover, and the vent hole cover is assembled on the fixed seat.

7. The vent valve for a urea tank as claimed in claim 2, wherein: a first accommodating cavity and a second accommodating cavity are arranged in the fixed seat; the first floating assembly is arranged in the first accommodating cavity, and the second floating assembly is arranged in the second accommodating cavity; the upper end of the first accommodating cavity is communicated with a first vent hole, a first communication hole communicated with a second opening is formed in the lower section area of the first accommodating cavity, and a second communication hole communicated with the second opening is formed in the lower section area of the second accommodating cavity; the second communication hole is positioned above the first communication hole;

the first communicating hole and the second communicating hole are respectively communicated with the second opening, or the second communicating hole is communicated with the second opening through the first accommodating cavity and the first communicating hole.

8. The vent valve for a urea tank as claimed in claim 7, wherein: the lower end of the fixed seat is detachably assembled with a lower cover.

9. The vent valve for a urea tank as claimed in claim 8, wherein: the lower cover is provided with a yielding hole, and the first floating piece penetrates through the yielding hole and extends out of the lower cover downwards; the periphery of the upper section of the first floating piece is convexly provided with a flange, the upper end of the first resetting elastic piece acts on the flange, and the lower end of the first resetting elastic piece acts on the lower cover.

10. The vent valve for a urea tank as claimed in claim 1, wherein: the second floating piece is a floating ball, the second reset elastic piece is a compression spring, the ball diameter of the floating ball is larger than the outer diameter of the compression spring, and the floating ball is placed at the upper end of the compression spring and the lower end of the floating ball extends into the compression spring.

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