A vacuum drying oven

Abstract

The application relates to a vacuum drying oven, which comprises a door body, an oven body provided with a drying cavity, a vacuum machine, a drying rack, a heating assembly for heating a heat-conducting medium and driving the heat-conducting medium to circulate in the drying rack, a sealing ring, a driving assembly, a first cover body and a first piston, the sealing ring is fixedly arranged in the oven body, a heat cavity and an expansion cavity which are not communicated with each other are formed in the sealing ring along the length direction of the sealing ring, the heating assembly drives the heat-conducting medium to circulate in the heat cavity and the drying rack or to separately circulate in the heat cavity, and the expansion cavity is filled with liquid driven by the first piston. By controlling the expansion and contraction of the sealing ring, the gap between the sealing ring and the door body is controlled, the pressure relief time is greatly shortened compared with a traditional pressure relief valve, meanwhile, the liquid is heated and expanded under the influence of the heat-conducting medium in the filling cavity, and the sealing ring can better adhere to the door body after being heated, so that the sealing reliability is ensured.

Description

Technical Field

[0001] This invention relates to the field of drying equipment, and in particular to a vacuum drying oven. Background Technology

[0002] Vacuum drying ovens are specifically designed for drying heat-sensitive, easily decomposed, and easily oxidized substances. During operation, they maintain a certain degree of vacuum within the chamber and can be filled with inert gas. They are particularly suitable for rapidly drying complex materials. Furthermore, with technological advancements, most vacuum drying ovens utilize intelligent digital temperature controllers for temperature setting, display, and control, making them even more convenient to use. Vacuum drying ovens are widely used in research and application fields such as biochemistry, chemical pharmaceuticals, medical and health care, agricultural research, and environmental protection. They can be used for powder drying, baking, and the sterilization and disinfection of various glass containers.

[0003] Current vacuum drying ovens employ a sealing strip between the door and the oven body to maintain a vacuum inside, ensuring a sealed environment when the door is closed. However, current vacuum drying ovens rely solely on a pressure relief valve for internal depressurization, resulting in a slow depressurization process and a reduced user experience. Summary of the Invention

[0004] To improve the depressurization rate of the chamber, this application provides a vacuum drying oven.

[0005] The vacuum drying oven provided in this application adopts the following technical solution:

[0006] A vacuum drying oven includes a door, a chamber with drying chambers, a vacuum machine, a drying rack, and a heating assembly for heating the drying rack. The door is hinged to the opening of the chamber. The drying rack is located inside the chamber and has a heat flow channel. The heating assembly is used to heat a heat-conducting medium and drive the heat-conducting medium to circulate in the heat flow channel. The oven also includes a sealing ring, a driving assembly, a first cover, and a first piston. The sealing ring is fixedly disposed on the side of the chamber facing the door and surrounds the opening of the chamber. The sealing ring has a non-communicating hot cavity and an expansion cavity along its own length. The two ends of the hot cavity are not connected to each other, while the two ends of the expansion cavity are connected.

[0007] The heating component is used to drive the heat-conducting medium to circulate separately within the hot cavity, or to circulate within the hot cavity and the hot flow channel;

[0008] The first cover is fixedly installed at the top of the box. The first cover has a first cavity. The first piston slides in the first cavity and divides the first cavity into a non-communicating filling cavity and a first outer cavity. The first outer cavity is connected to the outside. The box has a first connecting channel for connecting the filling cavity and the expansion cavity. The filling cavity, the first connecting channel and the expansion cavity are all completely filled with filling liquid. The driving component is used to drive the first piston to slide.

[0009] By adopting the above technical solution, the gap between the sealing ring and the door body is controlled by controlling the expansion and contraction of the sealing ring. Since the gap between the sealing ring and the door body can circle the opening of the chamber, the pressure relief time is significantly shortened compared to traditional pressure relief valves. At the same time, since the drying chamber cannot be heated during vacuuming, the heating component can switch to drive the heat transfer medium to circulate in the hot chamber. The heat transfer medium in the hot chamber can heat the sealing ring and the filling liquid. The filling liquid expands when heated, and the sealing ring can better fit against the door body, realizing thermally actuated active sealing. The sealing effect increases with the increase of temperature, ensuring the sealing reliability of the drying chamber under high vacuum.

[0010] Preferably, the thermal cavity is located on the side of the expansion cavity closer to the door body.

[0011] By adopting the above technical solution, the high-temperature heat-conducting medium flowing in the hot cavity can act more directly on the expansion cavity, while being far away from the drying cavity, thus reducing the impact on the vacuum machine.

[0012] Preferably, the heating assembly includes an electric heating box, a high-temperature pump, and several connecting pipes. The inlet of the high-temperature pump is connected to the heat-conducting medium inside the electric heating box, the outlet of the high-temperature pump is connected to the first end of the hot cavity, the tail end of the hot cavity is connected to the first end of the hot flow channel, and the tail end of the hot flow channel is positioned directly above the surface of the heat-conducting medium inside the electric heating box through the connecting pipes.

[0013] The heating assembly also includes a branch channel and a first reversing valve. The first reversing valve is installed at the connection between the hot cavity and the beginning of the hot flow channel. One end of the branch channel is connected to the first reversing valve, and the other end is placed directly above the surface of the heat-conducting medium in the electric heating box. The first reversing valve is used to control the connection between the hot cavity and the branch channel or the hot flow channel.

[0014] By adopting the above technical solution, the heating component can switch to separate circulation heating of the hot cavity. The first reversing valve is used to switch the heat transfer medium to circulate in the branch channel, passing through the hot cavity but not through the drying rack, or passing through both the hot cavity and the drying rack at the same time.

[0015] Preferably, the drive assembly includes a second cover, a second piston, a connecting rod, a second reversing valve, a spring, a pressure sensor, and an anti-reverse component. The second cover is fixedly mounted on the top of the housing. A second cavity is formed inside the second cover. The second piston slides in the second cavity along a sliding direction parallel to the first piston. The two ends of the connecting rod are respectively fixed to the first piston and the second piston. The second piston divides the second cavity into a non-communicating vacuum cavity and a second external cavity. The second external cavity is connected to the outside. The vacuum cavity is connected to the air inlet of the vacuum machine. The spring is located in the vacuum cavity, and the two ends of the spring abut against the second piston and the end wall of the vacuum cavity, respectively.

[0016] The second reversing valve includes a valve body, a valve core rotating within the valve body, and a motor driving the valve core to rotate. Two first channels and two second channels are sequentially formed along the circumference of the valve body. A balance channel connecting one of the first channels to the outside is formed on the inner wall of the vacuum chamber. A docking channel connecting the other first channel to the drying chamber is formed inside the chamber. The end of the second channel facing away from the valve core is connected to the vacuum chamber. An L-shaped selection channel is formed inside the valve core. The pressure sensor is installed on the side of the valve body facing the second piston.

[0017] When the vacuum machine is started, the valve core is driven to both ends of the selection channel and connects to the two second channels respectively; when the second piston moves to abut against the pressure sensor, the valve core is switched to connect the second channel and the docking channel, and the anti-retraction component is used to lock the position of the second piston; when drying is completed, the valve core is switched to connect the second channel and the balance channel, the spring drives the second piston to reset, and the anti-retraction component is unlocked.

[0018] By adopting the above technical solution, before the vacuum machine is started, the valve core is in a state where the two second channels are connected, and the vacuum chamber is in a sealed state. Then the vacuum machine is started to evacuate the vacuum chamber. The second piston overcomes the spring force and moves towards the second reversing valve until it comes into contact with the pressure sensor. The pressure sensor converts the pressure signal into an electrical signal output. The pressure sensor is electrically connected to the input terminal of the controller, and the output terminal of the controller is electrically connected to the motor through the drive module, driving the motor to run. The motor drives the valve core to rotate, connecting the second channel and the docking channel, that is, connecting the vacuum chamber and the drying chamber. At this time, the anti-retraction component locks the position of the second piston, and the second piston will not move backward due to the pressure change in the vacuum chamber. The vacuum machine continues to evacuate the air in the drying chamber until the required vacuum degree is reached in the drying chamber, and the vacuum machine stops running. Finally, after drying is completed, the motor drives the valve core to rotate, connecting the second channel and the balance channel, that is, sealing the drying chamber and connecting the vacuum chamber to the outside. Under the action of the spring, the second piston moves and pushes the first piston to reset through the connecting rod. The filling liquid in the expansion chamber returns to the filling chamber, the expansion chamber contracts, and a gap is formed between the sealing ring and the door body to release pressure.

[0019] Preferably, the anti-retraction component includes a first hook and a second hook. The first hook is fixedly disposed on the side of the second piston facing the second reversing valve, and the second hook is fixedly disposed on the output shaft of the motor. When the second channel and the docking channel are connected, the second hook hooks the first hook.

[0020] By adopting the above technical solution, the second piston is locked using a simple and reliable mechanical structure, ensuring the stability of the equipment's sealing state. When unlocking is required, the motor simply drives the valve core to rotate in the opposite direction, causing the second hook to disengage from the first hook, making the unlocking process convenient and efficient.

[0021] Preferably, the heating assembly further includes a switching element that acts on a high-temperature pump to extract and transport the heat-conducting medium in the hot cavity and hot flow channel back into the electric heating box.

[0022] By adopting the above technical solution, at the end of drying, the high-temperature pump can draw the heat-conducting medium in the hot cavity and hot flow channel back into the electric heating box, directly eliminating the heat source inside the box and accelerating the cooling inside the box. At the same time, after the heat-conducting medium in the hot cavity loses its support, the part of the sealing ring located in the hot cavity is more prone to deformation. When the filling liquid in the expansion cavity is pumped out, the sealing ring can quickly detach from the door.

[0023] Preferably, the switching component includes two first switching pipes, a second switching pipe, and three switching valves. One switching valve is located between the outlet of the high-temperature pump and the hot chamber, and is connected to one end of the first switching pipe. The second switching valve is located between the inlet of the high-temperature pump and the connecting pipe, and is connected to the other end of the first switching pipe. The third switching valve is located between the pump outlet and the first switching valve, and is connected to one end of the second switching pipe. The other end of the second switching pipe is located directly above the surface of the heat-conducting medium in the electric heating box. The switching valve is used to control the connection of two of the pipes.

[0024] By adopting the above technical solution, when it is necessary to drain the heat transfer medium in the hot cavity and hot flow channel, there is no need to add an additional liquid pump. A single high-temperature pump can directly extract the residual medium and send it back to the electric heating box. This not only greatly improves the drainage efficiency, but also avoids the risk of pipe blockage caused by the cooling and solidification of the residual medium, and reduces the manufacturing cost and subsequent maintenance difficulty of the equipment.

[0025] The main technical effects of this invention are reflected in the following aspects:

[0026] 1. This invention controls the gap between the sealing ring and the door by controlling the expansion and contraction of the sealing ring. Since the gap between the sealing ring and the door can circle the opening of the chamber, the pressure relief time is significantly shortened compared to traditional pressure relief valves. At the same time, since the gap in the drying chamber cannot be heated during vacuuming, the first reversing valve is used to switch the heat transfer medium to circulate in the branch channel. It passes through the hot chamber but not the drying rack. The heat transfer medium in the hot chamber heats the sealing ring and the filling liquid. The filling liquid expands when heated, and the heated sealing ring can better fit the door, realizing thermally actuated active sealing. The sealing effect increases with the increase of temperature, ensuring the sealing reliability of the drying chamber under high vacuum.

[0027] 2. In this invention, the hot cavity is located on the side of the expansion cavity close to the door body, so that the high-temperature heat-conducting medium flowing in the hot cavity can act more directly on the door body. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application.

[0029] Figure 2 This is a structural schematic diagram of the cabinet in the open state according to an embodiment of this application.

[0030] Figure 3 It is along Figure 1 A cross-sectional view along line AA in the middle.

[0031] Figure 4 yes Figure 3 Enlarged view of point B in the middle.

[0032] Figure 5 This is a schematic diagram of the docking of the sealing ring thermal cavity and the expansion cavity in an embodiment of this application.

[0033] Figure 6 This is a schematic diagram of the expansion cavity and the thermal cavity and their docking positions in an embodiment of this application.

[0034] Figure 7 It is along Figure 5 A partial sectional view of the CC line.

[0035] Figure 8 This is a schematic diagram of the entire cyclic system in an embodiment of this application.

[0036] Figure 9 This is a schematic diagram of the heat-conducting medium circulating only within the hot cavity in an embodiment of this application.

[0037] Figure 10 This is a schematic diagram of the circulation of the heat-conducting medium in the hot cavity and hot flow channel according to an embodiment of this application.

[0038] Figure 11 This is a schematic diagram of the heat transfer medium in the hot runner and hot cavity of this application being pumped back into the electric heating box by a high-temperature pump.

[0039] Figure 12 This is a schematic diagram of the structure of the second reversing valve in the embodiment of this application.

[0040] Figure 13 This is a schematic diagram of the anti-return component in an embodiment of this application.

[0041] Explanation of reference numerals in the attached drawings: 11. Door; 12. Box; 121. Drying chamber; 13. Vacuum machine; 14. Drying rack; 141. Hot runner; 15. Heating box; 151. Liquid level; 16. High-temperature pump; 17. Connecting pipe; 18. Branch channel; 19. First reversing valve; 2. Sealing ring; 21. Hot chamber; 22. Expansion chamber; 3. Drive assembly; 31. Second cover; 311. Vacuum chamber; 312. Second outer cavity; 32. Second piston; 321. Clearance groove; 33. Connecting rod; 35. Spring; 36. Pressure sensor; 37. First hook; 38. Second hook; 4. Switching component; 41. First switching pipe; 42. Second switching pipe; 43. Switching valve; 51. First cover; 52. First piston; 53. Filling cavity; 54. First outer cavity; 6. Second reversing valve; 61. Valve body; 62. Valve core; 63. Motor; 64. First channel; 65. Second channel; 66. Selection channel; 71. Balancing channel; 72. Connecting channel. Detailed Implementation

[0042] The following is in conjunction with the appendix Figures 1-13 This application will be described in further detail to make the technical solution of this application easier to understand and master.

[0043] This application discloses a vacuum drying oven.

[0044] Reference Figures 1-7 This embodiment of a vacuum drying oven includes a door 11, a box 12 with a drying chamber 121, a vacuum machine 13, a drying rack 14, and a heating assembly for heating the drying rack 14. The door 11 is hinged to the opening of the box 12, and when the door 11 is closed, it is fixed to the box 12 by a door lock. The drying rack 14 is located inside the box 12 and has a heat flow channel 141 inside. The heating assembly is used to heat the heat transfer medium and drive the heat transfer medium to circulate in the heat flow channel 141. It also includes a sealing ring 2, a driving assembly 3, a first cover 51, and a first piston 52. The sealing ring 2 is fixedly disposed on the side of the box 12 facing the door 11 and surrounds the opening of the box 12. The sealing ring 2 has a non-communicating hot cavity 21 and an expansion cavity 22 along its own length. The two ends of the hot cavity 21 are not connected to each other, while the two ends of the expansion cavity 22 are connected.

[0045] Reference Figure 1 , Figure 8 and Figure 9The heating component is used to drive the heat transfer medium to circulate individually within the hot cavity 21, or to circulate within the hot cavity 21 and the hot flow channel 141.

[0046] Reference Figures 1-8 The first cover 51 is fixedly installed at the top of the box 12. The first cover 51 has a first cavity. The first piston 52 slides in the first cavity and divides the first cavity into a non-communicating filling cavity 53 and a first outer cavity 54. The first outer cavity 54 is connected to the outside. The box 12 has a first connecting channel for connecting the filling cavity 53 and the expansion cavity 22. The filling cavity 53, the first connecting channel and the expansion cavity 22 are all completely filled with filling liquid. The driving component 3 is used to drive the first piston 52 to slide.

[0047] Reference Figures 1-8 The gap between the sealing ring 2 and the door 11 is controlled by controlling the expansion and contraction of the sealing ring 2. Since the gap between the sealing ring 2 and the door 11 can circle the opening of the chamber 12, the pressure relief time is greatly shortened compared with the traditional pressure relief valve. At the same time, since the drying chamber 121 cannot be heated during vacuuming, the heating component can switch to drive the heat transfer medium to circulate in the hot chamber 21. The heat transfer medium in the hot chamber 21 can heat the sealing ring 2 and the filling liquid. The filling liquid expands when heated, and the sealing ring 2 can better fit on the door 11, realizing thermally actuated active sealing. The sealing effect increases with the increase of temperature, ensuring the sealing reliability of the drying chamber 121 under high vacuum.

[0048] Reference Figure 2 , Figure 5 and Figure 7 The hot cavity 21 is located on the side of the expansion cavity 22 closer to the door 11. This allows the high-temperature heat-conducting medium flowing in the hot cavity 21 to act more directly on the expansion cavity 22, while keeping it away from the drying cavity 121, thus reducing the impact on the vacuum machine 13.

[0049] Reference Figures 2-7 The drive assembly 3 includes a second cover 31, a second piston 32, a connecting rod 33, a second reversing valve 6, a spring 35, a pressure sensor 36, and an anti-retraction component. The second cover 31 is fixedly mounted on the top of the housing 12, and a second cavity is formed inside the second cover 31. The second piston 32 slides in the second cavity along a sliding direction parallel to the first piston 52. The two ends of the connecting rod 33 are respectively fixed to the first piston 52 and the second piston 32. One end of the connecting rod 33 is integrally formed with the first piston 52, and the second piston 32 is sleeved on the other end of the connecting rod 33 and fixedly connected by screws. The second piston 32 divides the second cavity into a non-communicating vacuum cavity 311 and a second external cavity 312. The second external cavity 312 is connected to the outside, and the vacuum cavity 311 is connected to the air inlet of the vacuum machine 13. The spring 35 is located in the vacuum cavity 311, and the two ends of the spring 35 abut against the second piston 32 and the end wall of the vacuum cavity 311, respectively.

[0050] Reference Figure 1 , Figures 5-11 The heating assembly includes an electric heating box 15, a high-temperature pump 16, and several connecting pipes 17. The inlet of the high-temperature pump 16 is connected to the heat-conducting medium inside the electric heating box 15, and the outlet of the high-temperature pump 16 is connected to the beginning of the hot cavity 21. The end of the hot cavity 21 is connected to the beginning of the hot runner 141. The end of the hot runner 141 is positioned directly above the surface of the heat-conducting medium 151 inside the electric heating box 15 through the connecting pipes 17.

[0051] Reference Figure 1 , Figures 5-11 The heating assembly also includes a branch channel 18 and a first reversing valve 19. The first reversing valve 19 is installed at the connection between the hot cavity 21 and the beginning of the hot flow channel 141. One end of the branch channel 18 is connected to the first reversing valve 19, and the other end is placed directly above the surface of the heat transfer medium liquid 151 in the electric heating box 15. The first reversing valve 19 is used to control the connection between the hot cavity 21 and the branch channel 18 or the hot flow channel 141.

[0052] Reference Figure 1 , Figures 5-11 The heating component can switch to individually circulate heating the hot cavity 21. The first reversing valve 19 is used to switch the heat transfer medium to circulate in the branch channel 18, passing through the hot cavity 21 but not through the drying rack 14, or passing through both the hot cavity 21 and the drying rack 14 at the same time.

[0053] Reference Figure 3 , Figure 4 and Figure 12 The second reversing valve 6 includes a valve body 61, a valve core 62 rotating inside the valve body 61, and a motor 63 driving the valve core 62 to rotate. Two first channels 64 and two second channels 65 are sequentially opened along the circumference of the valve body 61. A balance channel 71 connecting one of the first channels 64 and the outside is opened on the inner wall of the vacuum chamber 311. A docking channel 72 connecting the other first channel 64 and the drying chamber 121 is opened inside the housing 12. The end of the second channel 65 facing away from the valve core 62 is connected to the vacuum chamber 311. An L-shaped selection channel 66 is opened inside the valve core 62. The pressure sensor 36 is installed on the side of the valve body 61 facing the second piston 32.

[0054] Reference Figure 1 , Figure 3 , Figure 4 and Figure 12 When the vacuum machine 13 is started, the valve core 62 is driven to both ends of the selection channel 66 and connects to the two second channels 65 respectively; when the second piston 32 moves to abut against the pressure sensor 36, the valve core 62 is switched to connect the second channel 65 and the docking channel 72, and the anti-retraction component is used to lock the position of the second piston 32; when drying is completed, the valve core 62 is switched to connect the second channel 65 and the balance channel 71, the spring 35 drives the second piston 32 to reset, and the anti-retraction component is unlocked.

[0055] Reference Figures 1-13 Before the vacuum machine 13 is started, the valve core 62 is in a state where the two second channels 65 are connected, and the vacuum chamber 311 is in a closed state. Then the vacuum machine 13 starts and evacuates the vacuum chamber 311. The second piston 32 overcomes the elastic force of the spring 35 and moves towards the second reversing valve 6 until it comes into contact with the pressure sensor 36. The pressure sensor 36 converts the pressure signal into an electrical signal output. The pressure sensor 36 is electrically connected to the input terminal of the controller. The output terminal of the controller is electrically connected to the motor 63 through the drive module, driving the motor 63 to run. The motor 63 drives the valve core 62 to rotate, so that the second channel 65 and the docking channel 72 are connected, that is, the vacuum chamber 311 is connected to the drying chamber 121. At this time, the anti-retraction component locks the position of the second piston 32. The second piston 32 will not retract due to the pressure change in the vacuum chamber 311. The vacuum machine 13 continues to evacuate the air in the drying chamber 121 until the required vacuum degree is reached in the drying chamber 121, and then the vacuum machine 13 stops running. After the final drying is completed, the motor 63 drives the valve core 62 to rotate, so that the second channel 65 is connected to the balance channel 71, which closes the drying chamber 121 and connects the vacuum chamber 311 to the outside. Under the action of the spring 35, the second piston 32 moves and pushes the first piston 52 to reset through the connecting rod 33. The filling liquid in the expansion chamber 22 returns to the filling chamber 53, and the expansion chamber 22 contracts, so that a gap is formed between the sealing ring 2 and the door body 11 to release pressure.

[0056] Refer to 3 and Figure 4 When the vacuum chamber 311 and the drying chamber 121 are not connected, and the second piston 32 moves close to the pressure sensor 36, the vacuum level in the vacuum chamber 311 is Pv1. After the vacuum chamber 311 and the drying chamber 121 are connected, the vacuum level in the drying chamber 121 when the vacuum requirement is met is Pv2, and Pv2 is greater than Pv1. Therefore, the spring 35 can reset the second piston 32 when air is released.

[0057] Reference Figure 4 and Figure 13 The anti-retraction component includes a first hook 37 and a second hook 38. The first hook 37 is fixedly disposed on the side of the second piston 32 facing the second reversing valve 6, and the second hook 38 is fixedly disposed on the output shaft of the motor 63. When the second channel 65 and the docking channel 72 are connected, the second hook 38 hooks the first hook 37.

[0058] Reference Figure 4 and Figure 13 The second piston 32 is locked using a simple and reliable mechanical structure, ensuring the stability of the equipment's sealing state. When unlocking is required, the motor 63 simply drives the valve core 62 to rotate in the opposite direction, which will cause the second hook 38 to disengage from the first hook 37, making the unlocking process convenient and efficient.

[0059] Reference Figure 1 , Figures 8-11 The heating assembly also includes a switching element 4, which acts on the high-temperature pump 16 to extract the heat-conducting medium in the hot cavity 21 and the hot flow channel 141 and transport it back to the electric heating box 15.

[0060] Reference Figure 1 , Figures 8-11 At the end of the drying process, the high-temperature pump 16 can draw the heat-conducting medium in the hot cavity 21 and the hot flow channel 141 back into the electric heating box 15, directly eliminating the heat source in the box 12 and accelerating the cooling of the box 12. At the same time, after the heat-conducting medium in the hot cavity 21 loses its support, the part of the sealing ring 2 located in the hot cavity 21 is more prone to deformation. When the filling liquid in the expansion cavity 22 is pumped out, the sealing ring 2 can quickly detach from the door 11.

[0061] Reference Figure 1 , Figures 8-11 The switching component 4 includes two first switching pipes 41, a second switching pipe 42, and three switching valves 43. One switching valve 43 is located between the outlet of the high-temperature pump 16 and the hot chamber 21, and is connected to one end of the first switching pipe 41. The second switching valve 43 is located between the inlet of the high-temperature pump 16 and the connecting pipe 17, and is connected to the other end of the first switching pipe 41. The third switching valve 43 is located between the pump outlet and the first switching valve 43, and is connected to one end of the second switching pipe 42. The other end of the second switching pipe 42 is located directly above the surface of the heat transfer medium liquid 151 in the electric heating box 15. The switching valves 43 are used to control the connection of two of them.

[0062] Reference Figure 1 , Figures 8-11 When it is necessary to drain the heat transfer medium in the hot cavity 21 and the hot flow channel 141, there is no need to add an additional liquid pump. The single high temperature pump 16 can directly extract the residual medium and send it back to the electric heating box 15. This not only greatly improves the drainage efficiency, but also avoids the risk of pipe blockage caused by the cooling and solidification of the residual medium, and reduces the manufacturing cost and later maintenance difficulty of the equipment.

[0063] Reference Figure 1 , Figures 8-11 The first directional valve 19 and the switching valve 43 can use the same rotary valve core 62 as the second directional valve 6, or a two-position three-way solenoid valve.

[0064] Reference Figure 1 and Figure 2The enclosure 12 has a display screen, several switches, and control buttons. The display screen shows the internal temperature, vacuum level, running time, set temperature, and vacuum level. The switches include a main power switch, heating switch, vacuum switch, and lighting switch. The entire device is controlled by a PLC controller. Since the PLC controller is paired with commonly used equipment and represents existing mature technology, its electrical connections and specific circuit structure will not be described in detail here.

[0065] Reference Figure 4 , Figure 8 and Figure 11 During the process of the high-temperature pump 16 extracting the heat transfer medium from the hot flow channel 141 and the hot cavity 21, a sensor is installed at the outlet of the hot cavity 21 to detect whether the heat transfer medium has been completely extracted. The sensor can control the valve core 62 to rotate automatically and actively release pressure through the controller.

[0066] Reference Figure 4 The second piston 32 has a clearance groove 321 on its side facing the valve body 61, which does not affect the communication between the second channel 65 and the vacuum chamber 311. Both the first cover 51 and the second cover 31 have a sealing ring at their bottom ends, and the first piston 52 and the second piston 32 are also fitted with sealing rings. In addition, in this embodiment, any location requiring sealing is equipped with a suitable sealing structure.

[0067] Of course, the above are just typical examples of this application. In addition, this application may have many other specific implementation methods. All technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection claimed in this application.

Claims

1. A vacuum drying oven, comprising a door body (11), an oven body (12) with a drying cavity (121), a vacuum machine (13), a drying rack (14) and a heating assembly for heating the drying rack (14), wherein the door body (11) is hinged at an opening of the oven body (12), the drying rack (14) is located in the oven body (12) and has a hot channel (141) inside, and the heating assembly is used for heating a heat-conducting medium, characterized in that: The sealing ring (2) is fixedly arranged on the side surface of the box body (12) facing the door body (11) and surrounds the opening of the box body (12); the sealing ring (2) is internally provided with a heat cavity (21) and an expansion cavity (22) which are not communicated with each other along the length direction of the sealing ring (2); ​ The heating assembly comprises an electric heating box (15), a high-temperature pump (16) and a plurality of connecting pipelines (17); the inlet of the high-temperature pump (16) is communicated with the heat-conducting medium in the electric heating box (15); the outlet of the high-temperature pump (16) is communicated with the first end of the heat cavity (21); the second end of the heat cavity (21) is communicated with the first end of the heat flow channel (141); the second end of the heat flow channel (141) is arranged above the liquid level (151) of the heat-conducting medium in the electric heating box (15) through the connecting pipeline (17); The heating assembly further comprises a branch channel (18) and a first reversing valve (19); the first reversing valve (19) is installed at the communication position between the heat cavity (21) and the first end of the heat flow channel (141); one end of the branch channel (18) is communicated with the first reversing valve (19), and the other end of the branch channel (18) is arranged above the liquid level (151) of the heat-conducting medium in the electric heating box (15); the first reversing valve (19) is used for controlling the communication between the heat cavity (21) and the branch channel (18) or the heat flow channel (141); The heating assembly is used for driving the heat-conducting medium to circulate between the heat cavity (21) and the electric heating box (15) or to circulate between the heat cavity (21), the heat flow channel (141) and the electric heating box (15); The first cover body (51) is fixedly arranged at the top end of the box body (12); the first cover body (51) is internally provided with a first cavity; the first piston (52) is slidably arranged in the first cavity and divides the first cavity into a filling cavity (53) and a first outer cavity (54) which are not communicated with each other; the first outer cavity (54) is communicated with the outside; the box body (12) is internally provided with a first communication channel for communicating the filling cavity (53) and the expansion cavity (22); the filling cavity (53), the first communication channel and the expansion cavity (22) are all completely filled with filling liquid; and the driving assembly (3) is used for driving the first piston (52) to slide.

2. The vacuum drying oven according to claim 1, characterized in that: The heat cavity (21) is located on the side of the expansion cavity (22) close to the door body (11).

3. The vacuum drying oven of claim 1, wherein: The driving assembly (3) comprises a second cover (31), a second piston (32), a connecting rod (33), a second reversing valve (6), a spring (35), a pressure sensor (36) and a retreat prevention piece, the second cover (31) is fixedly arranged at the top end of the box body (12), a second cavity is formed in the second cover (31), the second piston (32) slides in the second cavity along a sliding direction parallel to the first piston (52), the two ends of the connecting rod (33) are fixedly arranged on the first piston (52) and the second piston (32) respectively, the second piston (32) divides the second cavity into a vacuum cavity (311) and a second outer cavity (312) which are not communicated with each other, the second outer cavity (312) is communicated with the outside, and the vacuum cavity (311) is communicated with the air inlet of the vacuum machine (13); the spring (35) is located in the vacuum cavity (311), and the two ends of the spring (35) abut against the second piston (32) and the end wall of the vacuum cavity (311) respectively. The second reversing valve (6) comprises a valve body (61), a valve core (62) rotating in the valve body (61) and a motor (63) driving the valve core (62) to rotate; two first channels (64) and two second channels (65) are sequentially formed in the valve body (61) in the circumferential direction, a balance channel (71) is formed in the inner wall of the vacuum cavity (311) and is communicated with one of the first channels (64) and the outside, and a butt joint channel (72) is formed in the box body (12) and is communicated with the other first channel (64) and the drying cavity (121); one end of the second channel (65) away from the valve core (62) is communicated with the vacuum cavity (311), an L-shaped selection channel (66) is formed in the valve core (62), and the pressure sensor (36) is installed on the side surface of the valve body (61) facing the second piston (32). When the vacuum machine (13) is started, the valve core (62) is driven to be communicated with the two second channels (65) at the two ends of the selection channel (66); when the second piston (32) moves to abut against the pressure sensor (36), the valve core (62) is switched to be communicated with the second channel (65) and the butt joint channel (72), and the retreat prevention piece is used for locking the position of the second piston (32); after drying is completed, the valve core (62) is switched to be communicated with the second channel (65) and the balance channel (71), the spring (35) drives the second piston (32) to reset, and the retreat prevention piece is unlocked.

4. The vacuum drying oven of claim 3, wherein: The retreat prevention piece comprises a first hook (37) and a second hook (38), the first hook (37) is fixedly arranged on the side surface of the second piston (32) facing the second reversing valve (6), and the second hook (38) is fixedly arranged on the output shaft of the motor (63); when the second channel (65) and the butt joint channel (72) are communicated, the second hook (38) hooks the first hook (37).

5. The vacuum drying oven of claim 1, wherein: The heating assembly further comprises a switching piece (4) acting on the high-temperature pump (16), so that the high-temperature pump (16) extracts and transports the heat-conducting medium in the heat cavity (21) and the heat runner (141) back to the electric heating box (15).

6. A vacuum drying oven according to claim 5, characterized in that: The switching piece (4) comprises two first switching pipes (41), a second switching pipe (42) and three switching valves (43), one switching valve (43) is arranged between the outlet of the high temperature pump (16) and the hot cavity (21) and communicates with one end of the first switching pipe (41), the second switching valve (43) is arranged between the inlet of the high temperature pump (16) and the connecting pipe (17) and communicates with the other end of the first switching pipe (41), the third switching valve (43) is arranged between the outlet of the pump and the first switching valve (43) and communicates with one end of the second switching pipe (42), the other end of the second switching pipe (42) is arranged above the liquid level (151) of the heat conducting medium in the electric heating box (15); the switching valve (43) is used for controlling the communication of two paths.

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