Hydraulic pressure balance structure based on hydraulic cutting machine

Abstract

The invention discloses a hydraulic pressure balance structure based on a hydraulic cutting machine, which relates to the technical field of hydraulic cutting machines, is improved and optimized on the basis of a hydraulic transmission principle in the hydraulic cutting machine, and is different from a conventional hydraulic transmission mode in that an upper balloon and a lower balloon are additionally arranged at positions, corresponding to an upper oil cavity and a lower oil cavity, of a transmission guide rod respectively; on the basis of hydraulic transmission, hydraulic oil is converted into air pressure by extruding an upper balloon and a lower balloon, a freely movable ventilation guide rod is further additionally arranged at the inner position of a transmission guide rod, and the ventilation guide rod cannot directly affect the hydraulic transmission process; the key point is that the communicating / closing state between the upper balloon and the lower balloon is changed in the moving process of the air exchange guide rod, so that the air pressure in the upper balloon and the lower balloon is neutralized and balanced, and the hydraulic pressure in the upper oil cavity and the lower oil cavity is indirectly influenced; the key purpose is to actively share the counter-acting force in the transmission process so as to stabilize the cutting force.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic cutting machines, and in particular to a hydraulic pressure balancing structure based on a hydraulic cutting machine. Background Art

[0002] The working principle of the hydraulic cutting machine is to drive the cutting tool to cut through the hydraulic system. The key structure lies in the hydraulic control system. Please refer to the relevant content in the publication numbers CN113305900A and CN105234993A. The essence is to use hydraulic pressure as the power to drive the tool to cut.

[0003] The hydraulic output power is controlled according to the structural characteristics of different products. The applied hydraulic pressure needs to meet the cutting requirements, and the cutting force provided by the cutting machine is in a relatively stable state. However, in the process of cutting products, since the force is mutual, the tool will be subjected to a reaction force from the product. This reaction force is part of the shear resistance, and the reaction force received will also be transmitted back to the hydraulic transmission structure. The reaction force is specifically related to factors such as the product structural characteristics, shear temperature, shear speed, shear shape, and shear depth. When the structural characteristics of the tool and the product remain unchanged, other factors may change, resulting in an increase or decrease in the shear resistance, which will affect the shear force and the cutting quality, causing the cutting force transmitted to the product to fluctuate.

[0004] This application proposes a solution to this problem. Summary of the Invention

[0005] The purpose of the present invention is to provide a hydraulic pressure balancing structure based on a hydraulic cutting machine. In the hydraulic transmission process of the hydraulic cutting machine, because the cutting resistance generated in the actual cutting process is related to many factors, it will further affect the cutting force transmitted to the product, causing the cutting force to fluctuate significantly and affecting the cutting quality.

[0006] The object of the present invention can be achieved by the following technical solution: a hydraulic pressure balancing structure based on a hydraulic cutting machine includes an oil tank sleeve and an oil pump assembly, a transmission guide rod is slidably installed in the oil tank sleeve along the vertical direction, and a directional plate and a piston plate are arranged inside the oil tank sleeve along the direction from top to bottom, and an upper balloon and a lower balloon are respectively installed on the lower side of the transmission guide rod corresponding to the directional plate and the piston plate;

[0007] A ventilation guide rod is slidably installed in the transmission guide rod along the vertical direction, and ventilation grooves are provided at positions of the transmission guide rod corresponding to the upper balloon and the lower balloon, and a ventilation port is provided at a position of the ventilation guide rod corresponding to the upper balloon.

[0008] It is further configured as follows: the directional plate, the piston plate and the inner wall of the oil tank sleeve are respectively fixedly connected and slidably connected, and the transmission guide rod is respectively slidably connected and fixedly connected to the directional plate and the piston plate.

[0009] It is further configured as follows: an electric push rod and a pressure sensor component are installed at the top position of the oil tank sleeve, and the output end position of the electric push rod is fixedly connected to the ventilation guide rod.

[0010] It is further configured as follows: the interior of the ventilation guide rod is hollow, and the sensing position of the pressure sensing component is connected to the top position of the ventilation guide rod.

[0011] It is further configured as follows: the lower side positions of the directional plate and the piston plate inside the oil tank sleeve are respectively configured as an upper oil chamber and a lower oil chamber, and the oil outlet end and the oil return end of the oil pump assembly are respectively connected to the upper oil chamber and the lower oil chamber.

[0012] It is further configured as follows: the pressure sensing component is provided with a pressure sensing structure and an air pump component associated with the upper balloon and the lower balloon, and the pressure values in the upper balloon and the lower balloon are obtained in real time through the pressure sensing structure, and a control process of the associated air pump component and the oil pump component is provided in the pressure sensing component.

[0013] It is further configured as follows: the control process is set to the following state according to the movement mode of the ventilation guide rod:

[0014] State 1: The ventilation guide rod and the transmission guide rod keep moving synchronously, the interior of the upper balloon and the interior of the ventilation guide rod are in a closed state, while the interior of the lower balloon and the interior of the ventilation guide rod are in a connected state;

[0015] State 2: There is a misalignment between the movement of the ventilation guide rod and the movement of the transmission guide rod, and the interior of the upper and lower balloons is connected to the ventilation guide rod;

[0016] State three: In state one and state two, the air pump assembly of the pressure sensing assembly is used to inflate and pressurize the lower balloon or the upper balloon or to deflate and reduce the pressure.

[0017] The present invention has the following beneficial effects:

[0018] 1. The improvement is based on the hydraulic transmission principle of the hydraulic cutting machine. Its essence is to use the piston plate to produce a linear sliding process under the influence of hydraulic pressure. The difference from the conventional hydraulic transmission method is that the transmission guide rod is respectively equipped with an upper balloon and a lower balloon at the position of the upper oil chamber and the lower oil chamber. The upper balloon and the lower balloon do not directly affect the hydraulic transmission process. The key is that the hydraulic oil continuously squeezes the upper and lower balloons to form an oil pressure-air pressure conversion process or a reverse conversion process. The purpose of this is that when the cutting process is subjected to cutting resistance (reaction force), the hydraulic pressure fluctuation state generated by the hydraulic oil is directly borne by the upper balloon or the lower balloon, avoiding a direct impact on the cutting force during the hydraulic transmission process.

[0019] 2. Further improvement and optimization of the transmission guide rod is made by adding a freely movable ventilation guide rod inside it. The ventilation guide rod will not directly affect the hydraulic transmission process. The key is that the movement of the ventilation guide rod changes the connection / closure state between the upper balloon and the lower balloon. When the upper and lower balloons are in a connected state, the air pressure inside the two is "neutralized and balanced", which indirectly affects the liquid pressure in the upper oil chamber and the lower oil chamber, and further "actively distributes" or manually intervenes in the cutting resistance to stabilize the cutting force during the cutting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a schematic structural diagram of the hydraulic pressure balancing structure based on the hydraulic cutting machine proposed by the present invention;

[0022] Figure 2 This is a cross-sectional view of the oil tank sleeve in the hydraulic pressure balancing structure of the hydraulic cutting machine proposed by the present invention;

[0023] Figure 3 The hydraulic pressure balance structure of the hydraulic cutting machine proposed by the present invention Figure 2 Split diagram of ;

[0024] Figure 4 The hydraulic pressure balance structure of the hydraulic cutting machine proposed by the present invention Figure 2 The cutaway diagram in

[0025] Figure 5 The hydraulic pressure balance structure of the hydraulic cutting machine proposed by the present invention Figure 4 Front view of .

[0026] In the figure: 1. Oil tank cover; 2. Electric push rod; 3. Oil pump assembly; 4. Pressure sensor assembly; 5. Directional plate; 6. Upper balloon; 7. Piston plate; 8. Lower balloon; 9. Ventilation guide rod; 10. Transmission guide rod; 11. Ventilation port; 12. Ventilation groove. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Embodiment 1: In the hydraulic transmission process of a hydraulic cutting machine, since the cutting resistance generated during the actual cutting process is related to many factors, it will further affect the cutting force transmitted to the product, causing the cutting force to fluctuate significantly and affecting the cutting quality. In this regard, the following technical solution is proposed:

[0029] Reference Figures 1 to 5 The hydraulic pressure balancing structure based on the hydraulic cutting machine in this embodiment includes an oil tank sleeve 1 and an oil pump assembly 3. A transmission guide rod 10 is slidably installed in the oil tank sleeve 1 along the vertical direction. An directional plate 5 and a piston plate 7 are arranged inside the oil tank sleeve 1 from top to bottom. An upper balloon 6 and a lower balloon 8 are respectively installed on the lower side of the transmission guide rod 10 corresponding to the directional plate 5 and the piston plate 7.

[0030] A ventilation guide rod 9 is slidably installed in the transmission guide rod 10 in the vertical direction, and a ventilation groove 12 is provided at the position of the transmission guide rod 10 corresponding to the upper balloon 6 and the lower balloon 8, and a ventilation port 11 is provided at the position of the ventilation guide rod 9 corresponding to the upper balloon 6. The directional plate 5, the piston plate 7 and the inner wall of the oil tank sleeve 1 are respectively fixedly connected and slidably connected, and the transmission guide rod 10 and the directional plate 5 and the piston plate 7 are respectively slidably connected and fixedly connected.

[0031] Basic principle: The basic principle of the transmission rod in the hydraulic cutting machine is similar to the conventional oil pressure transmission structure. Figure 1 and Figure 5 , the hydraulic oil is continuously injected into the upper oil chamber of the oil pump assembly 3, causing the piston plate 7 therein to generate downward pressure and drive the entire transmission guide rod 10 to move downward, cooperating with the cutting tool installed at the lower end of the transmission guide rod 10 to achieve the cutting action. In this process, the hydraulic oil in the lower oil chamber flows back into the oil pump assembly 3 by squeezing, and conversely, the transmission guide rod 10 is moved upward by injecting hydraulic oil into the lower oil chamber. Specifically, the hydraulic pressure difference between the upper and lower sides of the piston plate 7 is utilized, which will not be explained in detail.

[0032] Key Targeting Figure 5 Explanation: When the upper oil chamber and the lower oil chamber are both filled with hydraulic oil, because the compression amount of the liquid is relatively small, the hydraulic oil will also generate inward liquid pressure on the upper balloon 6 and the lower balloon 8 when filling the upper oil chamber and the lower oil chamber, thereby further changing the air pressure in the upper balloon 6 and the lower balloon 8. In theory, the air pressure in the upper balloon 6 and the lower balloon 8 is proportional to the hydraulic pressure in the upper oil chamber and the lower oil chamber. The present invention mainly aims at the reaction force in the cutting process that affects the cutting force, and specifically adopts the oil-gas balance method to further change the cutting force. Its essence is to change the liquid pressure by converting air pressure into hydraulic pressure without changing the hydraulic oil injection / discharge method.

[0033] Example 2: Based on Example 1, additional explanation is given on the ventilation process between the upper balloon and the lower balloon:

[0034] An electric push rod 2 and a pressure sensing assembly 4 are installed at the top position of the oil tank cover 1. The output end position of the electric push rod 2 is fixedly connected to the ventilation guide rod 9. The interior of the ventilation guide rod 9 is hollow. The sensing position of the pressure sensing assembly 4 is connected to the top position of the ventilation guide rod 9. The lower side positions of the directional plate 5 and the piston plate 7 corresponding to the interior of the oil tank cover 1 are respectively set as the upper oil chamber and the lower oil chamber. The oil outlet end and the oil return end of the oil pump assembly 3 are respectively connected to the upper oil chamber and the lower oil chamber.

[0035] Solution description: Based on the first embodiment, in the initial state, the upper balloon 6 and the lower balloon 8 are filled with gas to ensure that they are in a normal expansion state, and the transmission guide rod 10 is the key transmission structure, targeting the air permeable groove 12 at the lower balloon 8 and referring to Figure 5 To illustrate, in essence, the transmission guide rod 10 is in communication with the interior of the upper balloon 6 and the lower balloon 8, and the ventilation guide rod 9 is provided with a ventilation port 11 at the position of the upper balloon 6, and a groove corresponding to the ventilation groove 12 at the lower balloon 8 is also provided at the position of the lower balloon 6. It can be directly understood that:

[0036] In the initial state, the interior of the lower balloon 8 is always connected to the interior of the ventilation guide rod 9 through the slots and the ventilation grooves 12, but the ventilation grooves 12 at the upper balloon 6 and the ventilation ports 11 on the ventilation guide rod 9 are in a staggered setting relationship, thereby ensuring that the internal space of the upper balloon 6 and the interior of the ventilation guide rod 9 are in a closed state. In this case, the upper balloon 6 and the interior of the lower balloon 8 exist independently and will not be connected to each other, and the two will only independently withstand the hydraulic changes in the upper oil chamber and the lower oil chamber. It should be further explained that: because the moving distance of the overall transmission guide rod 10 is only related to the hydraulic pressure difference between the upper oil chamber and the lower oil chamber, after the transmission guide rod 10 moves downward by a corresponding distance, the ventilation guide rod 9 needs to be driven downward by the electric push rod 2 by the corresponding distance, thereby ensuring that the interior of the upper balloon 6 is always in a closed state with the lower balloon 8;

[0037] It is further explained that when the transmission guide rod 10 moves downward, when there is a difference between the movement distance of the ventilation guide rod 9 and the movement distance of the transmission guide rod 10, the interior of the upper balloon 6 and the interior of the lower balloon 8 are connected, so that the air pressure inside the two gradually tends to be balanced. However, it is also necessary to further explain that:

[0038] Because the transmission guide rod 10 needs to be able to move downward, the hydraulic pressure in the upper oil chamber must always be greater than the hydraulic pressure in the lower oil chamber, so that the air pressure in the upper balloon 6 is much greater than the air pressure in the lower balloon 8. This can be indirectly understood as follows: the deformation of the upper and lower balloons 6 and 8 further reduces the hydraulic pressure difference between the upper and lower oil chambers, thereby affecting the downward movement of the transmission guide rod 10.

[0039] In combination with the above content, it needs to be explained again that the key content of the overall solution lies in the process of converting the hydraulic oil pressure into gas pressure, and further "neutralizing" the liquid pressure in the upper oil chamber and the lower oil chamber, and it is also necessary to further limit the setting method between the air groove 12 and the air port 11 at the upper balloon 6. Its essence is that when the air port 11 in the air guide rod 9 and the air groove 12 in the transmission guide rod 10 are connected, the air exchange efficiency between the gas in the upper balloon 6 relative to the air guide rod 9 is limited by setting the staggered method between the air port 11 and the air groove 12, thereby further changing the pressure relief efficiency of the air pressure in the upper balloon 6.

[0040] Example 3: Supplementary explanation of the overall oil and gas balance process is provided in combination with Example 1 and Example 2:

[0041] The pressure sensing component 4 is provided with a pressure sensing structure and an air pump component associated with the upper balloon 6 and the lower balloon 8. The pressure values in the upper balloon 6 and the lower balloon 8 are obtained in real time through the pressure sensing structure, and a control process associated with the air pump component and the oil pump component 3 is provided in the pressure sensing component 4.

[0042] Solution Description: As described in the relevant content of Example 1, the basic structure of the present invention lies in the oil pump assembly 3 injecting and discharging oil into the upper oil chamber and the lower oil chamber. The injection and discharge volumes of the oil pump assembly 3 per unit time are expressed as Qz and Qq respectively. This method is applied to a structure such as a conventional hydraulic telescopic rod, and the transmission speed, transmission distance, and hydraulic pressure value of the hydraulic telescopic rod can be directly calculated. This part is not described in the present invention.

[0043] The structure proposed by the present invention is to add an upper balloon 6 and a lower balloon 8 to the conventional hydraulic telescopic rod. The hydraulic oil injected into the upper oil chamber and the lower oil chamber will further squeeze the upper balloon 6 and the lower balloon 8 to produce air pressure changes. The pressure values in the upper balloon 6 and the lower balloon 8 are obtained in real time through the pressure sensing structure and expressed as Fs and Fx respectively. In order to ensure that the upper balloon 6 and the lower balloon 8 are in the same degree of compression state, the structure and shape of the upper balloon 6 and the lower balloon 8 are consistent. Therefore, the overall control process is set to the following state according to the movement mode of the ventilation guide rod 9:

[0044] State 1: The ventilation guide rod 9 and the transmission guide rod 10 move synchronously, and the interior of the upper balloon 6 and the interior of the ventilation guide rod 9 are in a closed state. In this case, as the hydraulic oil is injected into the upper oil chamber, Fs continues to rise. Because gas has an upper compression limit, after the pressure value Fs in the upper balloon 6 reaches the peak, it means that the upper oil chamber has been completely filled with hydraulic oil and begins to exert downward pressure on the piston plate 7. Assuming that Qq of the lower oil chamber is 0, but the hydraulic oil in the lower oil chamber is further subjected to the hydraulic pressure from the upper oil chamber due to the downward movement of the piston plate 7, the lower balloon 8 causes Fx to rise. In this state, Fx is proportional to Fs, and Fs is proportional to Qz;

[0045] State 2: When there is a difference between the moving distance of the ventilation guide rod 9 and the moving distance of the transmission guide rod 10, the air pressure converted from the hydraulic pressure on the upper balloon 6 will further affect the lower balloon 8, causing the lower balloon 8 to be in an outward deformation state. Because the volume of the lower balloon 8 is expanded, the internal air pressure is reduced. However, the outside of the lower balloon 8 is always filled with hydraulic oil. Therefore, the air pressure change inside the lower balloon 8 is reversely transmitted to the hydraulic oil in the lower oil chamber. The key point is that the hydraulic pressure in the upper and lower oil chambers is "neutralized" to a certain extent.

[0046] State 3: In states 1 and 2, the air pump assembly in the pressure sensing assembly can be further utilized. The air pump assembly mainly performs two actions, namely, replenishing air and increasing pressure or deflating air and reducing pressure, inside the upper balloon 6 or the lower balloon 8 through the ventilation guide rod 9. The purpose of this method is to further change the hydraulic pressure difference between the upper oil chamber and the lower oil chamber by actively intervening in the pressure changes in the upper balloon 6 and the lower balloon 8 during the changes of Fs and Fx in state 1 or state 2;

[0047] Combining state one and state two for explanation, the hydraulic pressure difference between the upper and lower oil chambers is set according to the cutting requirements of the hydraulic cutting machine, and Qz and Qq in the oil pump assembly are directly set, so that the downward movement distance and speed of the transmission guide rod 10 can be directly controlled. During this process, it is necessary to ensure that the upper balloon 6 and the lower balloon 8 are in a closed state, and the air pressure changes in the upper balloon 6 and the lower balloon 8 are continuously obtained during this process. In addition, because the reaction force in the cutting process is directly transmitted to the transmission guide rod 10, it will essentially generate an upward pressure trend in the upper oil chamber, resulting in an upward fluctuating trend in the air pressure change in the upper balloon 6.

[0048] In this state, the ventilation guide rod 9 is driven upward by the electric push rod 2 to ensure that the interior of the upper balloon 6 is in a connected state with the ventilation guide rod 9. Its purpose is to transmit the reaction force transmitted to the piston plate 7 to the interior of the upper balloon 6 through the hydraulic oil, and further feed back to the lower balloon 8, thereby further pressurizing the hydraulic oil in the lower oil chamber, so that the discharge amount Qq of the hydraulic oil from the lower oil chamber can be further controlled, and the lower balloon 8 and the upper balloon 6 can also be subjected to two actions of air replenishment and pressurization or air release and pressure reduction through the air pump assembly. Its purpose is to directly convert the reaction force of the transmission guide rod 10 and further adopt the autonomous mode of oil-gas conversion and the manual intervention mode of air replenishment and pressurization or air release and pressure reduction. The relevant parameters in the overall control process are not explained in detail in the present invention.

[0049] To sum up: the improvement and optimization is based on the hydraulic transmission principle in the hydraulic cutting machine. The difference from the conventional hydraulic transmission method is that the transmission guide rod is respectively provided with an upper balloon and a lower balloon at the position of the upper oil chamber and the lower oil chamber. On the basis of hydraulic transmission, the hydraulic oil is converted into air pressure by squeezing the upper balloon and the lower balloon, and a freely movable ventilation guide rod is further added to the internal position of the transmission guide rod. The ventilation guide rod will not directly affect the hydraulic transmission process. The key is that the movement of the ventilation guide rod changes the connection / closure state between the upper balloon and the lower balloon. Its purpose is to "neutralize and balance" the air pressure in the upper balloon and the lower balloon, thereby indirectly affecting the liquid pressure in the upper oil chamber and the lower oil chamber. The key purpose is to "actively share" the reaction force received during the transmission process and stabilize the cutting force.

[0050] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A hydraulic pressure balancing structure based on a hydraulic cutting machine, comprising an oil tank sleeve (1) and an oil pump assembly (3), characterized in that: A transmission guide rod (10) is slidably installed in the oil tank cover (1) in the vertical direction, and an orientation plate (5) and a piston plate (7) are arranged inside the oil tank cover (1) from top to bottom. An upper balloon (6) and a lower balloon (8) are respectively installed on the lower side of the transmission guide rod (10) corresponding to the orientation plate (5) and the piston plate (7); A ventilation guide rod (9) is slidably mounted in the transmission guide rod (10) along the vertical direction, and ventilation grooves (12) are provided at positions of the transmission guide rod (10) corresponding to the upper balloon (6) and the lower balloon (8), and a ventilation port (11) is provided at a position of the ventilation guide rod (9) corresponding to the upper balloon (6).

2. The hydraulic pressure balancing structure based on the hydraulic cutting machine according to claim 1, characterized in that: The directional plate (5), the piston plate (7) and the inner wall of the oil tank sleeve (1) are respectively fixedly connected and slidably connected, and the transmission guide rod (10) and the directional plate (5) and the piston plate (7) are respectively slidably connected and fixedly connected.

3. The hydraulic pressure balancing structure based on the hydraulic cutting machine according to claim 1, characterized in that: An electric push rod (2) and a pressure sensing assembly (4) are installed at the top end of the oil tank sleeve (1), and the output end of the electric push rod (2) is fixedly connected to the ventilation guide rod (9).

4. The hydraulic pressure balancing structure based on the hydraulic cutting machine according to claim 3, characterized in that: The interior of the ventilation guide rod (9) is hollow, and the sensing position of the pressure sensing component (4) is connected to the top position of the ventilation guide rod (9).

5. The hydraulic pressure balancing structure based on the hydraulic cutting machine according to claim 1, characterized in that: The lower side positions of the directional plate (5) and the piston plate (7) in the oil storage sleeve (1) are respectively set as an upper oil chamber and a lower oil chamber, and the oil outlet end and the oil return end of the oil pump assembly (3) are respectively connected to the upper oil chamber and the lower oil chamber.

6. The hydraulic pressure balancing structure based on the hydraulic cutting machine according to claim 1, characterized in that: The pressure sensing assembly (4) is provided with a pressure sensing structure associated with the upper balloon (6) and the lower balloon (8) and an air pump assembly, and the pressure values in the upper balloon (6) and the lower balloon (8) are obtained in real time through the pressure sensing structure. A control process associated with the air pump assembly and the oil pump assembly (3) is also provided in the pressure sensing assembly (4).

7. The hydraulic pressure balancing structure based on a hydraulic cutting machine according to any one of claims 1 to 6, characterized in that: The control process is set to the following states according to the movement mode of the ventilation guide rod (9): State 1: The ventilation guide rod (9) and the transmission guide rod (10) maintain synchronous movement, the interior of the upper balloon (6) and the interior of the ventilation guide rod (9) are in a closed state, and the interior of the lower balloon (8) and the interior of the ventilation guide rod (9) are in a connected state; State 2: There is a misalignment between the movement of the ventilation guide rod (9) and the movement of the transmission guide rod (10), and the interiors of the upper balloon (6) and the lower balloon (8) are in communication with the ventilation guide rod (9); State three: In state one and state two, the air pump assembly of the pressure sensing assembly (4) performs an air-inflating and pressure-increasing action or an air-deflation and pressure-reducing action on the lower balloon (8) or the upper balloon (6).

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