Patent Publication Number: US-2023160190-A1

Title: Air release valve and air pressure driven toilet water tank drain valve

Description:
TECHNICAL FIELD 
     The disclosure relates to a toilet water tank drain valve opened by air pressure, in particular to an air pressure driven toilet water tank drain valve and an air release valve thereof. 
     BACKGROUND 
     The traditional toilet water tank drain valve pushes the swing rod by pressing the button. The swing rod lifts the inner core tube of the drain valve and fits the hook of the half drainage limit device or the full drainage limit device. The water sealing piece at the lower end of the inner core tube separates from the water outlet of the valve body to open the half drainage limit or the full drainage limit function of the drain valve. When the water level of the water tank falls, the half drainage floating bucket of the half drainage limit device or the full drainage floating bucket of the full drainage limit device loses buoyancy, the inner core tube loses the hook support of the half drainage limit device or the full drainage limit device, the inner core tube is released from the hook and fall, the water sealing piece at the lower end of the inner core tube and the water outlet of the valve body are resealed, and the drainage is closed. 
     It can be seen from the above that the button, swing rod and inner core tube of the traditional toilet water tank drain valve are a mechanical lever transmission structure, which requires people to manually press the button to achieve the lifting of the inner core tube. Now the country advocates people to pursue a high-quality and beautiful life, and people hope to open the toilet water tank drain valve through electronic induction, instead of pressing the drain valve button installed on the toilet water tank, which is convenience, saves effort, and also avoids cross infection caused by different people pressing the drain valve button. 
     At present, there are air pressure driven toilet water tank drain valves on the market, which are electrically connected with the air pump through the electronic inductive switch and controller, and the air pump is connected with the telescopic airbag through the air pipe. The air pipe is connected with an electromagnetic pressure relief valve. When drainage is needed, people wave their hands above the electronic inductive switch, and the electronic inductive switch sends the inductive signal to the controller. The controller turns on the air pump, and the air pump inflates the telescopic airbag. The telescopic airbag expands and pushes the lifting cover on the inner core tube of the drain valve to drive the inner core tube to rise. When the inner core tube rises to clamp the hook of the half drainage limit device or the full drainage limit device of the drain valve, the electromagnetic pressure relief valve opens, and the air in the telescopic airbag is released through the electromagnetic pressure relief valve. The telescopic airbag uses its own elastic retraction to restore the original state, giving way to the falling of the inner core tube, the water sealing piece at the lower end of the inner core tube separates from the water outlet of the valve body, and the half drainage or full drainage function of the drain valve is enabled. When the water level of the water tank falls, and the half drainage floating bucket of the half drainage limit device or the full drainage floating bucket of the full drainage limit device loses buoyancy, the inner core tube loses the hook support of the half drainage limit device or the full drainage limit device, and the inner core tube falls after the clamp relationship between the inner core tube and the hook is relieved. Before the inner core tube falls, the water sealing piece at the lower end of the inner core tube and the water outlet of the valve body are resealed, such that the drainage is closed. 
     It can be seen from the above that the telescopic airbag needs to be depressurized through the electromagnetic pressure relief valve. Once the electromagnetic pressure relief valve is damaged and fails, the telescopic airbag can not be inflated or deflated, resulting in the abnormal use of the drain valve. In addition, the electromagnetic pressure relief valve has the disadvantages of high cost and power consumption. The inventor has developed an air release valve that uses a mechanical structure to realize the pressure relief of the telescopic airbag. 
     SUMMARY 
     The disclosure provides an air release valve of a toilet water tank drain valve opened by air pressure. The air release valve has reliable performance, low cost and no power consumption. 
     The disclosure also provides an air pressure driven toilet water tank drain valve, which has simple opening mode, reliable performance and low cost. 
     The technical solution to achieve the above object is shown as follows: 
     An air release valve, including a valve seat, a sliding block and a push block, wherein the valve seat is arranged at an upper part of the drain valve body through a mounting seat, a bottom of the valve seat is provided with an air release channel, one end of the air release channel is an air inlet, the other end of the air release channel forms an air release nozzle, the sliding block is located above the air release nozzle and is slidably arranged on the valve seat, and a bottom of the sliding block is provided with a sealing gasket for sealing the air release nozzle, a compressed elastic element is arranged between a side of the sliding block away from an inner core tube of the drain valve and the valve seat, a limit bump is arranged at a side of the sliding block close to the inner core tube of the drain valve, a limit stopper for clamping the limit bump is arranged at the valve seat, an upper stopper and a lower stopper are arranged at the side of the sliding block close to the inner core tube of the drain valve, a lower part of the upper stopper is an inclined plane, and the push block is arranged between the upper stopper and the lower stopper and is arranged at an upper part of the inner core tube of the drain valve. 
     A cylindrical cavity is formed on the valve seat, the air release channel is arranged at a bottom of the cylindrical cavity, the air inlet is communicated to an outer side of the bottom of the cylindrical cavity, and the air release nozzle is communicated to an inside of the cylindrical cavity; the sliding block comprises a column rod and a press rod, the column rod and an upper part of the press rod are integrally formed, the column rod is slidably arranged in the cylindrical cavity, and the sealing gasket is arranged at a bottom of the column rod; the compressed elastic element is arranged on an upper part of the column rod and located between a side far away from the inner core tube of the drain valve and the cylindrical cavity; the limit bump is arranged on a side of the column rod close to the inner core tube of the drain valve, the limit stopper is a limit hole, and the limit hole is correspondingly arranged on a side wall of the cylindrical cavity; the press rod is arranged outside the cylindrical cavity and near the side of the inner core tube of the drain valve, and the upper stopper and the lower stopper are respectively arranged on an upper and a bottom of the press rod. 
     The elastic element is a spring, the upper part of the column rod is provided with a transverse blind hole, the spring is placed in the transverse blind hole, and one end of the spring extends out of the transverse blind hole and butts against the side wall of the cylindrical cavity of the valve seat. 
     An air pressure driven toilet water tank drain valve, including a drain valve body, an inner core tube, a limit device, a telescopic airbag, an air pump, the air release valve, a controller, and an electronic inductive switch, wherein the air pump and the electronic inductive switch are electrically connected with the controller; the limit device comprises a half drainage limit device and a full drainage limit device, the half drainage limit device and the full drainage limit device are arranged in the drain valve body, the inner core tube passes through the drain valve body, a middle of the inner core tube is clamped with the half drainage limit device and the full drainage limit device respectively; a bottom of the inner core tube is provided with a water sealing piece to block the water outlet at a bottom of the drain valve body; an upper part of the inner core tube extends out of the drain valve body and is provided with a lifting cover, the lifting cover comprises a half drainage lifting cover and a full drainage lifting cover, and the half drainage lifting cover and the full drainage lifting cover are symmetrically arranged on a left side and a right side of an upper end of the inner core tube; the left and right telescopic airbags are respectively located under the half drainage lifting cover and the full drainage lifting cover and fixed on the drain valve body; the left telescopic airbag for the half drainage is connected with a half drainage air pipe of the air pump through an air pipe, and the right telescopic airbag for the full drainage is connected with a full drainage air pipe of the air pump, the valve seats of the left and the right air release valves are set on the mounting seat at the same time, separated from each other and arranged in a mirror setting with the inner core tube as an axis; the upper stopper and the lower stopper of the left and right air release valves are opposite arranged; the push block of the air release valve is divided into a left push part and a right push part on the inner core tube of the drain valve, the left push part is higher than the right push part, the left push part is located between the upper stopper and the lower stopper of the left air release valve, and the right push part is located between the upper stopper and the lower stopper of the right air release valve; the air inlet of the air release valve for the left half drainage is connected with the air pipe of the left telescopic airbag for the half drainage and the half drainage air pipe of the air pump, and the air inlet of the air release valve for the right full drainage is connected with the air pipe of the right telescopic airbag for the full drainage and the full drainage air pipe of the air pump. 
     The half drainage limit device in the drain valve body is higher than the full drainage limit device, the half drainage limit device comprises a half drainage floating bucket, a half drainage rotating frame and a half drainage hook, the half drainage rotating frame is rotatably fixed in the drain valve body, the half drainage floating bucket is rotatably arranged on one side of the half drainage rotating frame, and the other side of the half drainage rotating frame is provided with the half drainage hook; the full drainage limit device comprises a full drainage floating bucket, a full drainage rotating frame and a full drainage hook, the full drainage rotating frame is rotatably fixed in the drain valve body, the full drainage floating bucket is rotatably arranged on one side of the full drainage rotating frame, and the other side of the full drainage rotating frame is provided with the full drainage hook; the inner core tube passes through central holes of the half drainage rotating frame and the full drainage rotating frame respectively; the half drainage hook is clamped with a half drainage clamping point in the middle of the inner core tube, and the full drainage hook is clamped with a full drainage clamping point in the middle of the inner core tube. 
     The telescopic airbag is arranged in a cylinder body, the cylinder body is located below the lifting cover of the inner core tube and is placed on the drain valve body, the cylinder body is slidably provided with a piston push rod, a lower end of the piston push rod is connected with the telescopic airbag, and an upper end of the piston push rod extends out of the cylinder body to push the lifting cover of the inner core tube. 
     The working principle of the air release valve of the disclosure is as follows: When the drain valve is to stop drainage, the inner core tube falls to drive the water sealing piece to seal the water outlet of the drain valve, the lower stopper is pressed by the push block, the elastic element pushes the limit bump of the sliding block to insert into the limit stopper on the valve seat, and the sealing gasket at the bottom of the sliding block blocks the air release nozzle, thus sealing the air release nozzle. When the drain valve is opened for drainage, the inner core tube rises, the water sealing piece separates from the water outlet of the drain valve. When the inner core tube rises to clamp the limit device of the drain valve, the inclined plane of the lower part of the upper stopper is pushed upward by the push block, the elastic element is compressed, the sliding block laterally shifts on the valve seat, the limit bump of the sliding block exits the limit stopper on the valve seat, and the sealing gasket at the bottom of the sliding block separates from the air release nozzle, so as to open the air release nozzle for air release. 
     The working principle of the toilet water tank drain valve opened by the air pressure of the disclosure is that when the drain valve needs to be opened for drainage, people wave their hands above the electronic induction switch, the electronic induction switch sends an induction signal to the controller, the controller turns on the air pump, the air pump inflates the telescopic airbag, the telescopic airbag expands and pushes the lifting cover on the inner core tube of the drain valve, so as to drive the inner core tube to rise, and the water sealing piece separates from the water outlet of the drain valve, so as to open the half drainage or full drainage function of the drain valve. When the inner core tube rises to clamp the hook of the half drainage limit device or the full drainage limit device, the push block pushes against the inclined plane of the lower part of the upper stopper. The elastic element is compressed, the sliding block moves laterally on the valve seat, the limit bump of the sliding block exits the limit stopper on the valve seat, and the sealing gasket at the bottom of the sliding block separates from the air release nozzle, so as to open the air release nozzle for air release. The telescopic airbag uses its own elastic retraction to restore the original state, giving way to the falling of the inner core tube. After the drainage is completed, when the inner core tube falls and drives the water sealing piece to reseal the water outlet of the drain valve, the lower stopper is pressed by the push block, the elastic element pushes against the limit bump of the sliding block to insert into the limit stopper on the valve seat, the sealing gasket at the bottom of the sliding block blocks the air release nozzle, so as to seal the air release nozzle, and a closed air path is formed between the air pump and the telescopic airbag to prepare for the next drainage opening. 
     Compared with the existing air pressure driven toilet water tank drain valve, the disclosure uses the mechanical structure of the air release valve and removes the electromagnetic pressure relief valve, though the rising and falling motion of the inner core tube itself to push the sliding block of the air release valve up and down, and uses the expansion and contraction of the compressed elastic element to make the sliding block move laterally, so that the limit bump of the sliding block can insert or exit the limit stopper on the valve seat. Thus, the sealing gasket at the bottom of the sliding block can be opened or blocked the air release nozzle. The air release valve of the disclosure uses mechanical movement to open and close, without power consumption, has simple structure, reliable performance and low cost, and is more suitable for opening the drain valve of the toilet water tank by air pressure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of the disclosure are further described in detail below in combination with the accompanying drawings. 
         FIG.  1    is a perspective view of the air release valve of the disclosure assembled on the air pressure driven toilet water tank drain valve; 
         FIG.  2    is a sectional view of the air release valve of the disclosure; 
         FIG.  3    is an enlarged sectional view of part A of the air release valve in  FIG.  2   ; 
         FIG.  4    is a sectional view of the disclosure when the air pressure driven toilet water tank drain valve is in full drainage state; 
         FIG.  5    is a sectional view of the air release valve when the air pressure driven toilet water tank drain valve is in full drainage state; 
         FIG.  6    is an enlarged sectional view of part B of the air release valve in  FIG.  5    during full drainage; 
         FIG.  7    is a sectional view of the disclosure when the air pressure driven toilet water tank drain valve is in half drainage state; 
         FIG.  8    is a sectional view of the air release valve when the air pressure driven toilet water tank drain valve of the disclosure; 
         FIG.  9    is an enlarged sectional view of part C of the air release valve in  FIG.  8    during half drainage. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The disclosure is described in detail below in combination with the drawings and embodiments. 
     As shown in  FIG.  1    to  FIG.  3   , an air release valve  9  is provided, which includes a valve seat  1 , a sliding block  2  and a push block  3 . The valve seat  1  is arranged at the upper part of the drain valve body  5  through a mounting seat  90 . The bottom of the valve seat  1  is provided with an air release channel  11 , one end of the air release channel  11  is an air inlet  12 , and the other end of the air release channel  11  forms an air release nozzle  13 . The sliding block  2  is located above the air release nozzle  13  and is slidably arranged on the valve seat  1 , and a bottom of the sliding block  2  is provided with a sealing gasket  29  for sealing the air release nozzle  13 , wherein the sealing gasket  29  is a rubber gasket. A elastic element  22  that is compressed is arranged between the side of the sliding block away from the inner core tube  4  of the drain valve  7  and the valve seat  1 . A limit bump  28  is arranged at the side of the sliding block  2  close to the inner core tube  4 , and a limit stopper  14  for clamping and limiting the limit bump  28  is arranged at the valve seat  1 . An upper stopper  24  and a lower stopper  23  are arranged at the side of the sliding block  2  close to the inner core tube  4 , the lower part of the upper stopper  24  is an inclined plane  25 , and the push block  3  is arranged between the upper stopper  24  and the lower stopper  23  and is arranged at the upper part of the inner core tube  4 . 
     A cylindrical cavity  15  is formed on the valve seat  1 , the air release channel  11  is arranged at the bottom  151  of the cylindrical cavity  15 , the air inlet  12  is communicated to the outer side of the bottom  151  of the cylindrical cavity  15 , and the air release nozzle  13  is communicated to the inside of the cylindrical cavity  15 . The sliding block  2  includes a column rod  26  and a press rod  27 , and the column rod  26  and the upper part of the press rod  27  are integrally formed. The column rod  26  is slidably arranged in the cylindrical cavity  15 , and the sealing gasket  29  is arranged at the bottom of the column rod  26 . The compressed elastic element  22  is arranged on the upper part of the column rod  26  and located between the side far away from the inner core tube  4  and the cylindrical cavity  15 . The limit bump  28  is arranged on the side of the column rod  26  close to the inner core tube  4 . The limit stopper  14  is a limit hole, and the limit hole is correspondingly arranged on the side wall of the cylindrical cavity  15 . The press rod  27  is arranged outside the cylindrical cavity  15  and near the side of the inner core tube  4 , and the upper stopper  24  and the lower stopper  23  are respectively arranged on the upper and the bottom of the press rod  26 . The upper stopper  24  is a wedge-shaped block at the upper part of the press rod  26 , and the lower stopper  23  is an L-shaped transverse hook at the bottom of the press rod  26 . 
     The elastic element  22  is a spring, the upper part of the column rod  26  is provided with a transverse blind hole  21 , the spring is placed in the transverse blind hole  21 , and one end of the spring extends out of the transverse blind hole  21  and butts against the side wall of the cylindrical cavity  15  of the valve seat  1 . 
     The working principle of the air release valve of the disclosure is as follows: As shown in  FIG.  1    to  FIG.  3   , when the drain valve is closed to stop drainage, the inner core tube  4  falls to drive the water sealing piece  42  to seal the water outlet  51  of the drain valve  7 , the lower stopper  23  is pressed by the push block  3  (as shown in  FIG.  3   ), the elastic element  22  pushes the limit bump  28  of the sliding block  2  to insert into the limit hole of the limit stopper  14  on the valve seat  1 , and the sealing gasket  29  at the bottom of the sliding block  2  blocks the air release nozzle  13 , thus sealing the air release nozzle  13 . When the drain valve  7  is opened for drainage, the inner core tube  4  rises, the water sealing piece  42  separates from the water outlet of the drain valve  7 . When the inner core tube  4  rises to clamp the limit device  6  of the drain valve  7  (as shown in  FIG.  4    and  FIG.  7   ), the inclined plane  25  of the lower part of the upper stopper  24  is pushed upward by the push block  3 , such that the elastic element  22  is compressed, and the sliding block  2  moves upward and laterally shifts on the valve seat  1 , the limit bump  28  of the sliding block  2  exits the limit stopper  14  on the valve seat  1 , and the sealing gasket  29  at the bottom of the sliding block  2  separates from the air release nozzle  13 , so as to open the air release nozzle  13  for air release. 
     As shown in  FIG.  1    to  FIG.  9   , An air pressure driven toilet water tank drain valve  7  is provided, which includes a drain valve body  5 , an inner core tube  4 , a limit device  6 , a telescopic airbag  8 , an air pump (not shown), the air release valve  9 , a controller (not shown), and an electronic inductive switch (not shown), wherein the air pump and the electronic inductive switch are electrically connected with the controller. The limit device  6  includes a half drainage limit device  61  and a full drainage limit device  62 , wherein the half drainage limit device  61  and the full drainage limit device  62  are arranged in the drain valve body  5 . The inner core tube  4  passes through the drain valve body  5 , the middle of the inner core tube  4  is clamped with the half drainage limit device  61  and the full drainage limit device  62  respectively. The bottom of the inner core tube  4  is provided with a water sealing piece  42  to block the water outlet  51  at the bottom of the drain valve body  5 . The upper part of the inner core tube  4  extends out of the drain valve body  5  and is provided with a lifting cover  43 , wherein the lifting cover  43  includes a half drainage lifting cover  431  and a full drainage lifting cover  432 , and the half drainage lifting cover  431  and the full drainage lifting cover  432  are symmetrically arranged on the left side and the right side of the upper end of the inner core tube  4 . In order to adapt to the half drainage and the full drainage of the dual drain valve, the telescopic airbags shall be used independently, the left and right telescopic airbags  8  are respectively located under the half drainage lifting cover  431  and the full drainage lifting cover  432  and fixed on the drain valve body  5 . the left telescopic airbag  8  for the half drainage is connected with a half drainage air pipe  80  of the air pump through an air pipe  81 , and the right telescopic airbag  8  for the full drainage is connected with a full drainage air pipe  89  of the air pump. In order to adapt to the half drainage and the full drainage of the dual drain valve, air release valves shall be used independently, the valve seats  1  of the left and the right air release valves  9  are set on the mounting seat  90  at the same time, separated from each other and arranged in a mirror setting with the inner core tube  4  as an axis. Such that the upper stopper  24  and the lower stopper  23  of the left and right air release valves  9  are opposite arranged, as shown in  FIG.  3   , the push block  3  of the air release valve  9  is divided into a left push part  31  and a right push part  32  on the inner core tube  4  of the drain valve. The position of the left push part  31  is higher than that of the right push part  32 , the left push part  31  is located between the upper stopper  24  and the lower stopper  23  of the left air release valve  9 , and the right push part  32  is located between the upper stopper  24  and the lower stopper  24  of the right air release valve  9 . The air inlet  12  of the air release valve  9  for the left half drainage is connected with the air pipe  81  of the left telescopic airbag  8  for the half drainage and the half drainage air pipe  80  of the air pump, and the air inlet  12  of the air release valve  9  for the right full drainage is connected with the air pipe  81  of the right telescopic airbag  8  for the full drainage and the full drainage air pipe  89  of the air pump. 
     As shown in  FIG.  4    and  FIG.  7   , the half drainage limit device  61  in the drain valve body  5  is higher than the full drainage limit device  62 . The half drainage limit device  61  includes a half drainage floating bucket  611 , a half drainage rotating frame  612  and a half drainage hook  613 , the half drainage rotating frame  612  is rotatably fixed in the drain valve body  5 , the half drainage floating bucket  611  is rotatably arranged on one side of the half drainage rotating frame  612 , and the other side of the half drainage rotating frame  612  is provided with the half drainage hook  613 . The full drainage limit device  62  includes a full drainage floating bucket  621 , a full drainage rotating frame  622  and a full drainage hook  623 , the full drainage rotating frame  622  is rotatably fixed in the drain valve body  5 , the full drainage floating bucket  621  is rotatably arranged on one side of the full drainage rotating frame  622 , and the other side of the full drainage rotating frame  622  is provided with the full drainage hook  623 . The inner core tube  4  passes through central holes of the half drainage rotating frame  612  and the full drainage rotating frame  622  respectively. The half drainage hook  613  is clamped with a half drainage clamping point  44  in the middle of the inner core tube  4 , and the full drainage hook  623  is clamped with a full drainage clamping point  45  in the middle of the inner core tube  4 . 
     As shown in  FIG.  1   ,  FIG.  4    and  FIG.  7   , the telescopic airbag  8  is arranged in a cylinder body  82 , and the cylinder body  82  is located below the lifting cover  43  of the inner core tube  4  and is placed on the drain valve body  5 . A piston push rod  83  is slidably provided inside the cylinder body  82 , the lower end of the piston push rod  83  is connected with the telescopic airbag  8 , and the upper end of the piston push rod  83  extends out of the cylinder body  82  to push the lifting cover  43  of the inner core tube  4 . 
     As shown in  FIG.  4    to  FIG.  9   , the working principle of the air pressure driven toilet water tank drain valve of the disclosure is that when the drain valve  7  needs to be opened for drainage, the electronic induction switch (not shown) senses the motion of the people such as people wave their hands above the electronic induction switch, the number or the time of people wave their hands represents that the drain valve is to open the half drainage or the full drainage, as shown in  FIG.  7    to  FIG.  9   , if the electronic induction switch (not shown) senses the instruction of the half drainage, the instruction signal of the half drainage will be sent to the controller (not shown), the controller turns on the air pump (not shown), the air pump inflates the left telescopic airbag  8  for the half drainage through the half drainage air pipe  80 , the left telescopic airbag  8  for the half drainage expands and pushes the lifting cover  431  on the inner core tube  4  of the drain valve, so as to drive the inner core tube  4  to rise, and the water sealing piece  42  separates from the water outlet  51  of the drain valve  7 , so as to open the half drainage function of the drain valve. Since the position of the half limit device  61  is higher than that of the full limit device  62 , the half drainage clamping point  44  in the middle of the inner core tube  4  is clamped with the half drainage hook  613  firstly, at this time, the full drainage clamping point  45  in the middle of the inner core tube  4  dose not raise to the position of the full drainage hook  623  (as shown in  FIG.  7   ), such that the full drainage hook  623  cannot play a clamp limit function to the full drainage clamping point  45 . When the half drainage clamping point  44  in the middle of the inner core tube  4  is clamped with the half drainage hook  613  of the half drainage limit device  61 , because the position of the left push part  31  is higher than that of the right push part  32  in the push block  3 , the left push part  31  firstly contacts the inclined plane  25  of the lower part of the upper stopper  24  of the left air release valve  9 , the push block  3  pushes against the inclined plane  25  of the lower part of the upper stopper  24 . The elastic element  21  is compressed, the sliding block  2  moves upward and laterally shafts on the valve seat  1  of the air release valve  9 , the limit bump  28  of the sliding block  2  exits the limit stopper  14  on the valve seat  1 , and the sealing gasket  29  at the bottom of the sliding block  2  separates from the air release nozzle  13 , so as to open the air release nozzle  13  for air release. the left telescopic airbag  8  for the half drainage conducts air release through the air pipe  81  and the air release nozzle  13 , the left telescopic airbag  8  for the half drainage uses its own elastic retraction to restore the original state, giving way to the falling of the inner core tube  4 . After the half drainage is completed, the half drainage floating bucket  611  of the half drainage limit device  61  loses its buoyancy and falls, driving the half drainage rotating frame  612  to rotate, and the half drainage hook  613  disengages from the clamping of the half drainage clamping point  44  in the middle of the inner core tube  4 . When the inner core tube  4  falls and drives the water sealing piece  42  to reseal the water outlet  51  of the drain valve, the lower stopper  23  is pressed by the push block  3  (as shown in  FIG.  3   ), the elastic element  21  pushes against the limit bump  28  of the sliding block  2  to insert into the limit stopper  14  on the valve seat  1 , the sealing gasket  29  at the bottom of the sliding block  2  blocks the air release nozzle  13 , so as to seal the air release nozzle  13 , and a closed air path is formed between the air pump and the left telescopic airbag  8  for the half drainage to prepare for the next drainage opening. 
     Similarly, as shown in  FIG.  4   ,  FIG.  5    and  FIG.  6   , the working principle of the air pressure driven toilet water tank drain valve of the disclosure is that when the electronic induction switch (not shown) senses the instruction of the full drainage, the instruction signal of the full drainage will be sent to the controller (not shown), the controller turns on the air pump (not shown), the air pump inflates the right telescopic airbag  8  for the full drainage through the full drainage air pipe  89 , the right telescopic airbag  8  for the full drainage expands and pushes the lifting cover  432  at the right side of the inner core tube  4  of the drain valve, so as to drive the inner core tube  4  to rise, and the water sealing piece  42  separates from the water outlet  51  of the drain valve, so as to open the full drainage function of the drain valve. Since the position of the half limit device  61  is higher than that of the full limit device  62 , the full drainage clamping point  45  in the middle of the inner core tube  4  raise to the position of the full drainage hook  623 , at this time, the half drainage clamping point  44  is over the position of the half drainage hook  613 , such that the half drainage hook  613  cannot play a clamp limit function to the half drainage clamping point  44 . When the full drainage clamping point  45  in the middle of the inner core tube  4  is clamped with the full drainage hook  623  of the full drainage limit device  62 , because the position of the left push part  31  is higher than that of the right push part  32  in the push block  3 , the left push part  31  firstly contacts the inclined plane  25  of the lower part of the upper stopper  24  of the left air release valve  9 , the push block  3  pushes against the inclined plane  25  of the lower part of the upper stopper  24 . The elastic element  21  is compressed, the sliding block  2  moves upward and laterally shafts on the valve seat  1  of the air release valve  9 , the limit bump  28  of the sliding block  2  exits the limit stopper  14  on the valve seat  1 , and the sealing gasket  29  at the bottom of the sliding block  2  separates from the air release nozzle  13 , so as to open the air release nozzle  13 . Since the left telescopic airbag  8  for the half drainage is not inflated, the left telescopic airbag  8  for the half drainage does not push the left half drainage lifting cover  431  on the inner core tube  4 , and the left telescopic airbag  8  for the half drainage remains in the original state. At this moment, the right push part  32  of the push block  3  pushes against the inclined plane  25  of the lower part of the upper stopper  24  of the air release valve  9  for the right full drainage. The elastic element  21  is compressed, the sliding block  2  moves upward and laterally shafts on the valve seat  1 , the limit bump  28  of the sliding block  2  exits the limit stopper  14  on the valve seat  1 , and the sealing gasket  29  at the bottom of the sliding block  2  separates from the air release nozzle  13 , so as to open the air release nozzle  13 . the right telescopic airbag  8  for the full drainage conducts air release through the air pipe  81  and the air release nozzle  13 , the right telescopic airbag  8  for the full drainage uses its own elastic retraction to restore the original state, giving way to the falling of the inner core tube  4 . After the full drainage is completed, the full drainage floating bucket  621  of the full drainage limit device  62  loses its buoyancy and falls, driving the full drainage rotating frame  622  to rotate, and the full drainage hook  623  disengages from the clamping of the full drainage clamping point  45  in the middle of the inner core tube  4 . When the inner core tube  4  falls and drives the water sealing piece  42  to reseal the water outlet  51  of the drain valve, the lower stopper  23  is pressed by the push block  3 , the elastic element  21  pushes against the limit bump  28  of the sliding block  2  to insert into the limit hole of the limit stopper  14  on the valve seat  1 , the sealing gasket  29  at the bottom of the sliding block  2  blocks the air release nozzle  13 , so as to seal the air release nozzle  13 , and a closed air path is formed between the air pump and the right telescopic airbag  8  for the full drainage to prepare for the next drainage opening. 
     The above description is only a preferred embodiment of the disclosure, not a limitation on the design of the present application. Any equivalent substitutions made according to the design keys of the present application shall be fallen within the scope of the present application.