A safety valve structure and method capable of effectively reducing the opening and closing pressure difference

Abstract

The present invention discloses a safety valve structure and method capable of effectively reducing the opening and closing pressure difference, belonging to the field of valves. The device includes a valve body, a valve seat, a valve flap, a valve flap sleeve, a positioning rod, a valve stem, a guide sleeve, and a heat insulation disc; wherein, the guide sleeve is fixed to the top of the valve body, and the valve stem is coaxially sleeved inside the guide sleeve. The bottom of the valve stem extending outside the guide sleeve is fixed with a valve flap capable of forming a closed connection with the valve seat and a valve flap sleeve cooperating with the valve flap; the valve stem can slide along the guide sleeve, and a clearance fit is formed between the guide sleeve and the valve stem; the stroke of the valve flap in the main chamber is jointly restricted by the bottom of the guide sleeve and the top of the valve seat; the stroke of the valve flap sleeve in the main chamber is jointly restricted by the bottom of the positioning rod and the top of the valve seat. The present invention can effectively reduce the opening and closing pressure difference during the opening and closing process of the safety valve and improve the opening and closing performance of the safety valve.

Description

Technical Field

[0001] The present invention belongs to the field of safety valves, and particularly relates to a safety valve structure and method that can effectively reduce the opening and closing pressure difference. Background Art

[0002] A safety valve is a special valve in which the closing member is in a normally closed state under the action of an external force. When the medium pressure in the equipment or pipeline rises above the specified value, the medium is discharged to the outside of the system to prevent the medium pressure in the pipeline or equipment from exceeding the specified value. The safety valve belongs to the category of automatic valves and is mainly used on boilers, pressure vessels, and pipelines to control the pressure not to exceed the specified value, playing an important protective role in personal safety and equipment operation. The safety valve plays a safety protection role in the system. When the system pressure exceeds the specified value, the safety valve opens, discharging a part of the gas / fluid in the system into the atmosphere / out of the pipeline, so that the system pressure does not exceed the allowable value, thus ensuring that the system does not have an accident due to excessive pressure.

[0003] The opening and closing pressure difference of a safety valve is an important performance index of the safety valve. Its calculation method is: the difference between the set pressure and the reseating pressure, usually expressed as a percentage of the reseating pressure to the set pressure. The smaller the opening and closing pressure difference, the better the action performance of the safety valve. The size of the opening and closing pressure difference depends on the lift curves of the safety valve at the set pressure and the reseating pressure. The smaller the gap between the two curves, the smaller the opening and closing pressure difference. However, for conventional safety valves, the distance between the two lift curves is relatively large, the opening and closing pressure difference is relatively large, and the action performance of the safety valve is not good. Therefore, it is of great significance to study a safety valve structure and method that can effectively reduce the opening and closing pressure difference. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a safety valve structure and method that can effectively reduce the opening and closing pressure difference. The present invention controls the bottom area in contact with the fluid at different lifting heights by means of the combined separation of the valve disc and the valve disc sleeve, effectively reducing the slope of the lift curve, so that the lift curve under the reseating pressure can be appropriately shifted upward to reduce the opening and closing pressure difference and improve the action performance of the safety valve.

[0005] The specific technical solutions adopted by the present invention are as follows:

[0006] In a first aspect, the present invention provides a safety valve structure that can effectively reduce the opening and closing pressure difference, including a valve body, a valve seat, a valve flap, a valve stem, and a guide sleeve, and further including a valve flap sleeve and a positioning rod; a plurality of vertical positioning rods are fixedly arranged along the circumference at the bottom of the guide sleeve; the valve flap is a frustum-shaped structure with a cross-section gradually shrinking from top to bottom, and the valve flap sleeve includes a valve flap sleeve body, a spring, and a connecting rod assembly; the valve flap sleeve body is coaxially sleeved on the outer wall surface of the valve flap and is a funnel-shaped structure with a gradually shrinking radial dimension; the connecting rod assembly includes a first rod body, a second rod body, and a third rod body; a plurality of first chambers are circumferentially formed on the inner side of the valve flap sleeve body, and a plurality of second chambers that can communicate with the first chambers are circumferentially formed on the outer side of the valve flap; the first rod body is horizontally arranged, one end is fixed to the valve flap sleeve by a spring, the elastic force of the spring is the same as the axial direction of the first rod body, and when the spring is in its original length, the other end of the first rod body is located in the second chamber; the third rod body is located below the positioning rod and is vertically arranged, one end is hinged with the second rod body, and the other end can extend out of the top of the valve flap sleeve body; the other end of the second rod body is hinged with the spring connection end of the first rod body; when the positioning rod contacts the third rod body and provides a downward pressure, the first rod body can be moved to the left and completely enter the first chamber through the hinging action of the second rod body.

[0007] Preferably, a heat insulation disc is provided between the valve body and the valve cover.

[0008] Preferably, the valve flap and the valve flap sleeve have the same height.

[0009] Preferably, the number of the positioning rods, the springs, and the connecting rod assemblies is the same, and they are evenly arranged along the circumference of the inner cavity of the valve body.

[0010] Preferably, the first rod body can only axially move in the horizontal direction, and the third rod body can only axially move in the vertical direction.

[0011] Preferably, the third rod body is directly below the positioning rod.

[0012] In a second aspect, the present invention provides a method for reducing the opening and closing pressure difference of the safety valve structure according to any one of the first aspects, specifically as follows:

[0013] S1. When the safety valve is in the closed state, the valve seat contacts the valve flap to form a seal to prevent the medium from leaking. At this time, the spring is in its original length, one end of the first rod body is located in the second chamber, and the top end of the third rod body extends out of the top of the valve flap sleeve body;

[0014] When the medium inlet pressure increases to be greater than the set pressure of the safety valve, the valve flap begins to move upward; since one end of the first rod body is located in the second chamber and is in contact with the valve flap, the valve flap drives the valve flap sleeve to move upward, and at this time, the medium contacts the common bottom surface of the valve flap and the valve flap sleeve;

[0015] S2. When the medium pushes the valve flap and the valve flap sleeve to rise further, the top of the third rod body contacts the positioning rod. Under the pressure of the positioning rod, the third rod body moves downward. Through the hinge action of the second rod body, the first rod body moves leftward to compress the spring and completely enters the first chamber of the valve flap sleeve. At this time, the cooperation between the valve flap and the valve flap sleeve is lost, the valve flap continues to move upward, and the valve flap sleeve no longer moves upward due to the action of the positioning rod. The bottom area in contact with the medium at different heights changes, the slope of the lift curve of the safety valve decreases, and the opening and closing pressure difference of the safety valve is reduced.

[0016] S3. When the inlet pressure of the medium continues to decrease, the valve flap begins to fall back. When the valve flap falls back to the position of the valve flap sleeve, it will re - cooperate with it and drive the valve flap sleeve to fall together. When the valve flap sleeve falls, the third rod body disengages from the contact with the positioning rod, the spring resets, and drives the first rod body and the third rod body back to the initial position.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a safety valve structure and method that can effectively reduce the opening and closing pressure difference, enabling the lift curve under the reseating pressure of the safety valve to move upward appropriately, thereby reducing the opening and closing pressure difference of the safety valve and improving the operating performance of the safety valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of the safety valve structure;

[0020] Figure 2 is a schematic diagram of the valve flap sleeve structure;

[0021] Figure 3 is a schematic diagram of the connecting rod structure;

[0022] Figure 4 is a schematic diagram of the separation of the valve flap and the valve flap sleeve during the rising process of the safety valve. Figures a and b are two different states;

[0023] Figure 5 is a lift curve graph of the safety valve. Among them, Ⅰ is the lift curve under the set pressure, Ⅱ is the lift curve of the conventional safety valve under the reseating pressure, and Ⅲ is the lift curve of the designed safety valve under the reseating pressure;

[0024] In the figure: 1. Valve body; 2. Valve seat; 3. Valve flap sleeve; 4. Valve flap; 5. Positioning rod; 6. Valve rod; 7. Guide sleeve; 8. Heat insulation disc; 9. Valve flap sleeve main body; 10. Spring; 11. Connecting rod assembly; 12. First rod body; 13. Second rod body; 14. Third rod body. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present invention will be further described and explained below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment in the present invention can be combined correspondingly on the premise that there is no conflict with each other.

[0026] As Figure 1 shown, a safety valve structure capable of effectively reducing the opening and closing pressure difference provided by the present invention. In addition to the conventional valve body 1, valve seat 2, valve flap 4, valve stem 6, and guide sleeve 7, the safety valve structure further includes a valve flap sleeve 3 and a positioning rod 5. Specifically, the guide sleeve 7 is fixed to the top of the valve body 1. The valve stem 6 is coaxially sleeved inside the guide sleeve 7. The bottom of the valve stem 6 extending outside the guide sleeve 7 is fixed with a valve flap 4 that can form a closed connection with the valve seat 2 and a valve flap sleeve 3 that cooperates with the valve flap 4. The valve stem 6 can slide along the guide sleeve 7, and a clearance fit is formed between the guide sleeve 7 and the valve stem 6. The stroke of the valve flap 3 in the main chamber is limited jointly by the bottom of the guide sleeve 7 and the top of the valve seat 2. The stroke of the valve flap sleeve 3 in the main chamber is limited jointly by the bottom of the positioning rod 5 and the top of the valve seat 2.

[0027] The structures and connection methods of each component will be specifically described below.

[0028] A plurality of vertical positioning rods 5 are fixed along the circumference at the bottom of the guide sleeve 7. The valve flap 4 is a frustum-shaped structure with a cross-section gradually shrinking from top to bottom. The valve flap sleeve 3 is located on the outer periphery of the valve flap 4 and includes a valve flap sleeve body 9, a spring 10, and a connecting rod assembly 11. As Figure 2 shown, the valve flap sleeve body 9 is coaxially sleeved on the outer wall surface of the valve flap 4 and is a funnel-shaped structure with a gradually shrinking radial dimension. As Figure 3 shown, the connecting rod assembly 11 includes a first rod body 12, a second rod body 13, and a third rod body 14. The first rod body 12 and the second rod body 13 are hinged, and the second rod body 13 and the third rod body 14 are hinged. A plurality of first chambers are circumferentially opened on the inner side of the valve flap sleeve body 9, and a plurality of second chambers are circumferentially opened on the outer side of the valve flap 4. In the initial state, the first chambers are communicated with the second chambers, and the number and positions of the first chambers and the second chambers are the same and corresponding. The first rod body 12 is horizontally arranged, and one end is fixed to the valve flap sleeve 3 through the spring 10. The elastic force of the spring 10 is the same as the axial direction of the first rod body 12. When the spring 10 is in its original length, the other end of the first rod body 12 is located in the second chamber. The third rod body 14 is located below the positioning rod 5 and is vertically arranged. One end is hinged with the second rod body 13, and the other end can extend out of the top of the valve flap sleeve body 9. The other end of the second rod body 13 is hinged to the spring 10 connection end of the first rod body 12. When the positioning rod 5 contacts the third rod body 14 and provides a downward pressure, the first rod body 12 can be moved to the left and completely enter the first chamber through the hinging action of the second rod body 13.

[0029] In this embodiment, a heat insulation disc 8 is provided between the valve body 1 and the valve cover; the valve disc 4 and the valve disc sleeve 3 have the same height; the positioning rods 5, the springs 10 and the connecting rod assemblies 11 are equal in number and are uniformly arranged circumferentially along the inner cavity of the valve body 1; the first rod body 12 can only axially move in the horizontal direction, and the third rod body 14 can only axially move in the vertical direction; the third rod body 14 is located directly below the positioning rod 5.

[0030] As Figure 4 shown, according to the method for reducing the opening and closing pressure difference of the above safety valve structure, it is as follows:

[0031] S1. When the safety valve is in the closed state, the valve seat 2 contacts the valve disc 4 to form a seal to prevent the medium from leaking. At this time, the spring 10 is in its original length. One end of the first rod body 12 is located in the second chamber, and the top end of the third rod body 14 extends out of the top of the valve disc sleeve body 9.

[0032] When the inlet pressure of the medium increases to be greater than the setting pressure of the safety valve, the valve disc 4 starts to move upward; since one end of the first rod body 12 is located in the second chamber and is in contact with the valve disc 4, the valve disc 4 drives the valve disc sleeve 3 to move upward. At this time, the medium contacts the common bottom surface of the valve disc 4 and the valve disc sleeve 3.

[0033] S2. When the medium pushes the valve disc 4 and the valve disc sleeve 3 to rise further, the top of the third rod body 14 contacts the positioning rod 5. Under the pressure of the positioning rod 5, the third rod body 14 moves downward. Through the hinged action of the second rod body 13, the first rod body 12 moves leftward to compress the spring 10 and completely enters the first chamber of the valve disc sleeve 3; at this time, the cooperation between the valve disc 4 and the valve disc sleeve 3 is lost, the valve disc 4 continues to move upward, and the valve disc sleeve 3 no longer moves upward due to the positioning rod 5. The bottom area of the medium in contact at different heights changes, and the slope of the lift curve of the safety valve decreases, reducing the opening and closing pressure difference of the safety valve.

[0034] S3. When the inlet pressure of the medium continues to decrease, the valve disc 4 starts to fall back; when the valve disc 4 falls back to the position of the valve disc sleeve 3, it will re-cooperate with it and drive the valve disc sleeve 3 to fall together; when the valve disc sleeve 3 falls, the third rod body 14 disengages from the contact with the positioning rod 5, and the spring 10 resets, driving the first rod body 12 and the third rod body 14 back to the initial position.

[0035] As Figure 5 shown, curve II is the lift curve of a conventional safety valve at the reseating pressure, and curve III is the lift curve of the safety valve designed by the present invention at the reseating pressure. Since the valve disc sleeve disengages at a certain height, the slope of the lift curve changes at this point, and the overall slope is smaller than that of the lift curve of the conventional safety valve. Therefore, this lift curve can be appropriately shifted upward, so that the difference between it and the lift curve I at the setting pressure decreases, that is, the opening and closing pressure difference of the safety valve decreases.

[0036] The embodiments described above are only a preferred solution of the present invention, but they are not intended to limit the present invention. Those of ordinary skill in the relevant technical field can still make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A safety valve structure that can effectively reduce the opening and closing pressure difference, comprising a valve body (1), a valve seat (2), a valve flap (4), a valve rod (6) and a guide sleeve (7). Characterized in that it further comprises a valve flap sleeve (3) and a positioning rod (5); a plurality of vertical positioning rods (5) are fixedly arranged along the circumference at the bottom of the guide sleeve (7); the valve flap (4) is a frustum-shaped structure with a cross-section gradually shrinking from top to bottom, and the valve flap sleeve (3) comprises a valve flap sleeve main body (9), a spring (10) and a connecting rod assembly (11); the valve flap sleeve main body (9) is coaxially sleeved on the outer wall surface of the valve flap (4) and is a funnel-shaped structure with gradually shrinking radial dimensions; the connecting rod assembly (11) comprises a first rod body (12), a second rod body (13) and a third rod body (14); a plurality of first chambers are circumferentially formed on the inner side of the valve flap sleeve main body (9), and a plurality of second chambers that can communicate with the first chambers are circumferentially formed on the outer side of the valve flap (4); the first rod body (12) is horizontally arranged, one end is fixed to the valve flap sleeve (3) through the spring (10), the elastic force of the spring (10) is the same as the axial direction of the first rod body (12), and when the spring (10) is in its original length, the other end of the first rod body (12) is located in the second chamber; the third rod body (14) is located below the positioning rod (5) and is vertically arranged, one end is hinged with the second rod body (13), and the other end can extend out of the top of the valve flap sleeve main body (9); the other end of the second rod body (13) is hinged with the spring (10) connection end of the first rod body (12); when the positioning rod (5) contacts the third rod body (14) and provides a downward pressure, the first rod body (12) can be moved to the left and completely enter the first chamber through the hinging action of the second rod body (13).

2. A safety valve structure that can effectively reduce the opening and closing pressure difference according to claim 1, Characterized in that a heat insulation disc (8) is provided between the valve body (1) and the valve cover.

3. A safety valve structure that can effectively reduce the opening and closing pressure difference according to claim 1, Characterized in that the valve flap (4) and the valve flap sleeve (3) have the same height.

4. A safety valve structure that can effectively reduce the opening and closing pressure difference according to claim 1, Characterized in that the number of the positioning rods (5), the springs (10) and the connecting rod assemblies (11) is the same, and they are evenly arranged along the circumference of the inner cavity of the valve body (1).

5. A safety valve structure that can effectively reduce the opening and closing pressure difference according to claim 1, Characterized in that the first rod body (12) can only axially move in the horizontal direction, and the third rod body (14) can only axially move in the vertical direction.

6. A safety valve structure that can effectively reduce the opening and closing pressure difference according to claim 1, Characterized in that the third rod body (14) is directly below the positioning rod (5).

7. A method for reducing the opening and closing pressure difference of the safety valve structure according to any one of claims 1 to 6, Characterized in that specifically as follows: S1. When the safety valve is in the closed state, the valve seat (2) contacts the valve flap (4) to form a seal to prevent the medium from leaking. At this time, the spring (10) is in its original length. One end of the first rod body (12) is located in the second chamber, and the top end of the third rod body (14) extends out of the top of the valve flap sleeve body (9). When the inlet pressure of the medium increases to be greater than the setting pressure of the safety valve, the valve flap (4) begins to move upward. Since one end of the first rod body (12) is located in the second chamber and contacts the valve flap (4), the valve flap (4) drives the valve flap sleeve (3) to move upward. At this time, the medium contacts the common bottom surface of the valve flap (4) and the valve flap sleeve (3). S2. When the medium pushes the valve flap (4) and the valve flap sleeve (3) to rise further, the top of the third rod body (14) contacts the positioning rod (5). Under the pressure of the positioning rod (5), the third rod body (14) moves downward. Through the hinge action of the second rod body (13), the first rod body (12) moves leftward to compress the spring (10) and completely enters the first chamber of the valve flap sleeve (3). At this time, the cooperation between the valve flap (4) and the valve flap sleeve (3) is lost. The valve flap (4) continues to move upward, and the valve flap sleeve (3) no longer moves upward due to the action of the positioning rod (5). The bottom area of the medium in contact at different heights changes, and the slope of the lift curve of the safety valve decreases, reducing the opening and closing pressure difference of the safety valve. S3. When the inlet pressure of the medium continues to decrease, the valve flap (4) begins to fall back. When the valve flap (4) falls back to the position of the valve flap sleeve (3), it will re-cooperate with it and drive the valve flap sleeve (3) to fall together. When the valve flap sleeve (3) falls, the third rod body (14) disengages from the contact with the positioning rod (5), and the spring (10) resets, driving the first rod body (12) and the third rod body (14) back to the initial position.

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