High-precision mechanical pressure switch

Abstract

The invention discloses a high-precision mechanical pressure switch, and belongs to the technical field of pressure switches. Comprising an air pressure sensing element and a pressure reduction module, the step-down module is arranged in front of the sensing surface. The pressure reduction module comprises a cover plate, a valve seat, an elastic piece, a valve element, a connecting seat and a piston. A groove is formed in one side, corresponding to the air pressure sensing element, of the cover plate; the valve seat is pressed in the groove in an interference manner; the elastic piece is close to the cover plate and is arranged in the air inlet cavity; one end of the valve core abuts against the elastic piece, and the other end of the valve core is tightly pressed on the valve seat; the connecting seat end face is connected with the cover plate; a connecting seat inner cavity is formed in one side, corresponding to the cover plate, of the connecting seat and is communicated with the atmosphere through an exhaust port; the piston is designed to be of a variable-diameter structure, the core portion of the piston is through, and the piston is arranged in an inner cavity of the connecting base and opposite to the valve seat. The pressure switch is applied to the aspect of pressure control, solves the technical problem that the control precision of an existing mechanical pressure switch is generally not high, and has the characteristic of high control precision.

Description

Technical Field

[0001] The present invention belongs to the technical field of pressure switches, and particularly relates to a high-precision mechanical pressure switch. Background Art

[0002] A pressure switch, also known as a pressure controller or pressure relay, is a device used for pressure monitoring, alarm, or control. According to whether external power supply is required, it is divided into a mechanical pressure switch and an electronic pressure switch. The mechanical pressure switch does not rely on external power supply, can directly drive the load, and is convenient for installation and use. It is widely used in many fields such as petroleum, chemical industry, blowers, power plants, ships, refrigeration, and rail transit. The mechanical pressure switches sold on the market usually adopt a direct push structure or a lever structure to directly collect the pressure of the monitored medium. Their control accuracy is generally not high and is easily affected by temperature changes. When high control accuracy is required, people have to use sensors or electronic pressure switches instead of mechanical pressure switches. However, sensors or electronic pressure switches have relatively strict requirements for the use environment, high costs, relatively complex control, and are not suitable for directly connecting to the load.

[0003] A large amount of research and test data show that the control accuracy of a mechanical pressure switch has a great relationship with the range size and the set point height, that is, the smaller the range of the pressure switch, the higher the control accuracy; when the ranges are the same, the lower the set point of the pressure switch, the higher the control accuracy. A mechanical pressure switch mainly consists of components such as a pneumatic sensing element, a spring, an adjustment mechanism, and a switching device. Among them, the pneumatic sensing element and the spring are the main components that determine the range size of the pressure switch. Usually, the larger the acting area of the pneumatic sensing element, the higher the control accuracy of the pressure switch; the smaller the force value and stiffness of the spring, the higher the control accuracy of the pressure switch.

[0004] However, the larger the acting area of the pneumatic sensing element, the greater the thrust generated by the measured medium, and the greater the spring force required. Therefore, the control accuracy of mechanical pressure switches is generally not high, and as the range and set value increase, the drift amount of mechanical pressure switches gradually becomes larger. Summary of the Invention

[0005] The details of one or more embodiments of the present invention are set forth in the following drawings and description to make other features, objects, and advantages of the present application more concise and understandable.

[0006] The present invention provides a high-precision mechanical pressure switch, which solves the technical problem that the control accuracy of existing mechanical pressure switches is generally not high, and has the characteristic of high control accuracy.

[0007] The present invention provides a high-precision mechanical pressure switch, comprising: a pneumatic sensing element with a sensing surface at one end; a pressure reducing module disposed in front of the sensing surface, including: a cover plate having a groove on one side corresponding to the pneumatic sensing element; a valve seat press-fitted in the groove with interference and forming an air inlet cavity with the cover plate; an elastic member disposed in the air inlet cavity near the cover plate; a valve core placed in the air inlet cavity, with one end abutted against the elastic member and the other end tightly pressed against the valve seat; a connecting seat located between the cover plate and the pneumatic sensing element, connected to the cover plate, having a connecting seat inner cavity on one side corresponding to the cover plate, and the connecting seat inner cavity is communicated with the atmosphere through an exhaust port; a piston placed in the connecting seat inner cavity and disposed opposite to the valve seat, including a valve head, an exhaust groove, S1 and S2 surfaces; the piston has a first end and a second end opposite to the first end, a central portion of the first end protrudes outward to form the valve head, the valve head penetrates through the valve seat and abuts against the valve core, and the surface of the non-valve head portion of the first end opposite to the valve seat is the S1 surface; a central portion of the second end protrudes outward and is inserted into the connecting seat inner cavity, and the surface of the non-central protruding portion of the second end opposite to the connecting seat is the S2 surface; the area of the S1 surface is larger than the area of the S2 surface; one end of the exhaust groove is communicated with the exhaust port, and the other end penetrates through the valve head and is communicated to the valve core; an exhaust cavity is formed between the piston and the exhaust port, a balance cavity is formed between the S2 surface and the connecting seat, and a transition cavity is formed between the S1 surface and the cover plate, the valve core and the valve seat; a working cavity is formed between the sensing surface and the connecting seat.

[0008] In some embodiments, the piston moves in the connecting seat inner cavity under the action of air pressure, and changes the on-off state between the air inlet cavity and the transition cavity through the valve head; the balance cavity is communicated with the air inlet cavity through an air path to collect the inlet pressure of the pressure switch; the air inlet cavity pressure acts on the S2 surface; the transition cavity pressure acts on the S1 surface; the transition cavity is connected to the working cavity through an air path; the exhaust cavity is communicated with the atmosphere.

[0009] In some embodiments, the cover plate and the connecting seat are sealed by a sealing ring; the exhaust cavity and the balance cavity, and the balance cavity and the transition cavity are respectively sealed by a K-shaped ring.

[0010] In some embodiments, the pneumatic sensing element includes a bellows and a flange, one end of the bellows is connected to the flange, and the other end of the bellows defines the sensing surface.

[0011] In some embodiments, it further includes a housing having a housing inner cavity, and the pneumatic sensing element is disposed in the housing inner cavity; the housing is connected to the connecting seat.

[0012] In some embodiments, it further includes a spring box disposed in the housing inner cavity, and a push rod disposed between the pneumatic sensing element and the spring box; under the thrust of the spring box, one end of the push rod can abut against the sensing surface; the other end of the push rod is connected to the spring box.

[0013] In some of these embodiments, the spring box includes a guide sleeve, a spring seat, a spring, an adjustment seat, and a fine-tuning nut; the guide sleeve is fixed to the outer circumferential surface of the spring seat; the spring is disposed between the spring seat and the adjustment seat; the fine-tuning nut is fixed to the spring seat by threads and is used to adjust the pre-compression amount of the microswitch contact button.

[0014] In some of these embodiments, an adjustment mechanism is further included, and the adjustment mechanism is screwed into and abuts against the adjustment seat from the end of the housing away from the step-down module.

[0015] In some of these embodiments, a dust-proof pad and a protective cover are further included, and the dust-proof pad and the protective cover are fixed to the end of the housing away from the step-down module.

[0016] In some of these embodiments, a connector is further included, and the connector is fixed to the side of the housing and feeds back the on / off state of the internal contacts of the microswitch through a cable.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The present invention provides a high-precision mechanical pressure switch. By providing a pre-step-down module, the monitored pressure is reduced according to a certain ratio or pressure difference, so as to achieve the purpose of reducing the monitored pressure, further matching a pressure switch with a small range and a low set point, and finally achieving the effect of improving the system control accuracy;

[0019] The present invention provides a high-precision mechanical pressure switch. The step-down module reduces the pressure in a manner of air pressure balance, and its accuracy is little affected by the ambient temperature, which can reduce the influence of temperature change on the accuracy of the pressure switch;

[0020] The present invention provides a high-precision mechanical pressure switch. By providing a transition chamber, the isolation between the monitored pressure and the actual contact pressure of the pressure switch is realized, the moisture in the gas path can be discharged, and the requirement for the quality of the medium by the pressure switch is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present invention, form a part of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0022] Figure 1 is a schematic structural diagram of the mechanical pressure switch provided by the embodiment of the present invention;

[0023] Figure 2 is a schematic structural diagram of the step-down module provided by the embodiment of the present invention;

[0024] Figure 3 is a diagram of the gas path connection state of the mechanical pressure switch provided by the embodiment of the present invention;

[0025] Figure 4 Another air circuit connection state diagram of the mechanical pressure switch provided by the embodiment of the present invention;

[0026] Description of the drawings: 1. Step-down module; 101. Cover plate; 102. Connecting seat; 1021. Exhaust port; 1022. Boss; 103. Piston; 1031. Valve head; 1032. Exhaust groove; 1033. S1 surface; 1034. S2 surface; 104. Valve core; 105. Valve seat; 106. Elastic member;

[0027] 2. Air pressure sensing element; 201. Flange; 202. Bellows; 203. Sensing surface;

[0028] 3. Spring box; 301. Guide sleeve; 302. Spring seat; 303. Spring; 304. Adjusting seat; 305. Fine-tuning nut;

[0029] 4. Housing; 5. Dust-proof pad; 6. Protective cover; 7. Micro switch; 8. Push rod; 9. Connector; 10. Adjusting mechanism;

[0030] 1101. Intake cavity; 1102. Exhaust cavity; 1103. Balance cavity; 1104. Transition cavity; 1105. Acting cavity. Detailed implementation manners

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be described and explained below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0032] Obviously, the accompanying drawings in the following description are only some examples or embodiments of the present invention. For those of ordinary skill in the art, the present invention can also be applied to other similar scenarios based on these drawings without making creative efforts. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed by the present invention, some design, manufacturing or production changes based on the technical content disclosed by the present invention are only conventional technical means and should not be understood as the content disclosed by the present invention being insufficient.

[0033] References to "embodiments" in the present invention mean that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in the present invention can be combined with other embodiments without conflict.

[0034] Unless otherwise defined, the technical terms or scientific terms involved in the present invention shall have the ordinary meaning understood by those of ordinary skill in the technical field to which the present invention pertains. The words such as "a", "an", "one kind", "the" and the like involved in the present invention do not indicate a limitation in quantity and can represent a singular or plural number. The terms "comprising", "including", "having" and any variations thereof involved in the present invention are intended to cover non-exclusive inclusion; for example, a process, method, system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or units, but may further include steps or units not listed, or may further include other steps or units inherent to these processes, methods, products or devices. The terms "connected", "coupled" and the like involved in the present invention are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0035] Existing mechanical pressure switches mainly consist of components such as a pneumatic sensing element 2, a spring 303, an adjustment mechanism 10, and a switching device. Among them, the pneumatic sensing element 2 and the spring 303 are the main components that determine the range of the pressure switch. Generally, the larger the acting area of the pneumatic sensing element 2, the higher the control accuracy of the pressure switch; the smaller the force value and stiffness of the spring 303, the higher the control accuracy of the pressure switch. However, the larger the acting area of the pneumatic sensing element 2, the greater the thrust generated by the measured medium, and the greater the force required for the spring 303. Therefore, the control accuracy of existing mechanical pressure switches is generally not high, and as the range and set value increase, the drift amount of the mechanical pressure switch gradually becomes larger.

[0036] If the monitored medium is subjected to a pressure reduction treatment (such as proportional pressure reduction, differential pressure reduction, etc.), a pressure switch with a smaller range and a lower set point can be selected for monitoring or control. Compared with the pressure switch with a large range and a high set point used before the pressure reduction, the control accuracy can be effectively improved.

[0037] An embodiment of the present invention provides a high-precision mechanical pressure switch integrated with a pre-pressure reduction module 1. Figure 1 Schematic diagram of the structure of the mechanical pressure switch according to an embodiment of the present invention. Refer to Figure 1As shown in the figure, the mechanical pressure switch includes a pneumatic sensing element 2 and a pressure reduction module 1. One end of the pneumatic sensing element 2 has a sensing surface 203; the pressure reduction module 1 is arranged in front of the sensing surface 203. By setting the front pressure reduction module 1, the monitored pressure is reduced according to a certain ratio or pressure difference, so as to achieve the purpose of reducing the monitored pressure, further matching the pressure switch with a small measuring range and a low set point, and finally improving the system control accuracy.

[0038] As Figure 2 shown, the pressure reduction module 1 includes a cover plate 101, a valve seat 105, an elastic member 106, a valve core 104, a connecting seat 102 and a piston 103. Among them, the side of the cover plate 101 corresponding to the pneumatic sensing element 2 has a groove; the valve seat 105 is press-fitted in the groove with interference and forms an air inlet cavity 1101 with the cover plate 101; the elastic member 106 is arranged in the air inlet cavity 1101 close to the cover plate 101. Further, the elastic member 106 can be a balance spring; the valve core 104 is placed in the air inlet cavity 1101, one end abuts against the elastic member 106, and the other end is tightly pressed on the valve seat 105 under the action of the balance spring force; the connecting seat 102 is located between the cover plate 101 and the pneumatic sensing element 2, and the end face is fixedly connected with the cover plate 101 by connecting screws; the side of the connecting seat 102 corresponding to the cover plate 101 has a cavity of the connecting seat 102, and the cavity of the connecting seat 102 is communicated with the atmosphere through an exhaust port 1021.

[0039] The piston 103 is designed with a variable diameter structure and its core is penetrated. It is placed in the cavity of the connecting seat 102 and is arranged opposite to the valve seat 105; it includes a valve head 1031, an exhaust groove 1032, an S1 surface 1033 and an S2 surface 1034; the piston 103 has a first end and a second end opposite to the first end. The central part of the first end protrudes outward to be the valve head 1031. The valve head 1031 penetrates the valve seat 105 and abuts against the valve core 104. The surface of the non-valve head 1031 part of the first end opposite to the valve seat 105 is the S1 surface 1033; the central part of the second end protrudes outward and is inserted into the cavity of the connecting seat 102. The non-central protruding part of the second end is the S2 surface 1034 opposite to the connecting seat 102; the area of the S1 surface 1033 is larger than the area of the S2 surface 1034; one end of the exhaust groove 1032 is communicated with the exhaust port 1021, and the other end penetrates the valve head 1031 and is communicated to the valve core 104; an exhaust cavity 1102 is formed between the piston 103 and the exhaust port 1021, a balance cavity 1103 is formed between the S2 surface 1034 and the connecting seat 102, and a transition cavity 1104 is formed between the S1 surface 1033 and the cover plate 101, the valve core 104 and the valve seat 105; an action cavity 1105 is formed between the sensing surface 203 and the connecting seat 102. Since the S2 surface 1034 of the piston 103 is smaller than the S1 surface 1033, the pressure reduction module 1 can reduce the collected intake pressure according to a certain ratio and then act on the pneumatic sensing element 2.

[0040] The step-down module 1 in the above mechanical pressure switch steps down the pressure by means of air pressure balance. Its accuracy is little affected by the ambient temperature, which can reduce the influence of temperature change on the accuracy of the pressure switch. By setting up the transition cavity 1104, the monitoring pressure is separated from the actual contact pressure of the pressure switch, moisture in the gas path can be discharged, and the requirement for the quality of the medium by the pressure switch is reduced.

[0041] As Figure 3 、 4 shown, the piston 103 moves within the inner cavity of the connecting seat 102 under the action of air pressure, and changes the on-off state between the air inlet cavity 1101 and the transition cavity 1104 through the valve head 1031; the balance cavity 1103 is connected to the air inlet cavity 1101 through a gas path to collect the inlet air pressure of the pressure switch; the pressure in the air inlet cavity 1101 acts on the S2 surface 1034; the pressure in the transition cavity 1104 acts on the S1 surface 1033; the transition cavity 1104 is connected to the acting cavity 1105 through a gas path; the exhaust cavity 1102 is connected to the atmosphere.

[0042] To ensure the sealing performance, the cover plate 101 and the connecting seat 102 are sealed by a sealing ring; the exhaust cavity 1102 and the balance cavity 1103, and the balance cavity 1103 and the transition cavity 1104 are respectively sealed by K-shaped rings.

[0043] As Figure 1 shown, the air pressure sensing element 2 includes a bellows 202 and a flange 201. One end of the bellows 202 is welded to the flange 201, and the other end of the bellows 202 defines the sensing surface 203. A sealing ring is installed between the flange 201 and the housing 4, and is fixed by the housing 4 and the step-down module 1. The bellows 202 can axially expand and contract freely under the action of air pressure. Further, the air pressure sensing element 2 of the present invention is not limited to the illustrated welded bellows form, and can also be other air pressure sensing methods such as piston type and diaphragm type.

[0044] The above mechanical pressure switch further includes a housing 4. The housing 4 has an inner cavity of the housing 4, and the air pressure sensing element 2 is arranged in the inner cavity of the housing 4; the housing 4 is connected to the connecting seat 102. To ensure the sealing performance, a sealing ring is installed between the air pressure sensing element 2 and the housing 4.

[0045] Further, the above mechanical pressure switch further includes a spring box 3 arranged in the inner cavity of the housing 4, and a push rod arranged between the air pressure sensing element 2 and the spring box 3; under the thrust of the spring box 3, one end of the push rod can abut against the sensing surface 203; the other end of the push rod is connected to the spring box 3. The spring box 3 can slide in the inner cavity of the housing 4 with the change of air pressure under the action of the push rod 8 and the air pressure sensing element 2.

[0046] In some of these embodiments, the spring box 3 includes a guide sleeve 301, a spring seat 302, a spring 303, an adjustment seat 304, and a fine-tuning nut 305; the guide sleeve 301 is fixed to the outer ring surface of the spring seat 302 for guiding; the spring 303 is placed between the spring seat 302 and the adjustment seat 304; the fine-tuning nut 305 is fixed to the spring seat 302 by threads and is used to adjust the pre-compression amount of the contact button of the micro switch 7. The mechanical pressure switch further includes an adjustment mechanism 10 which is screwed into one end of the housing 4 away from the step-down module 1 and abuts against the adjustment seat 304. The step-down module 1 is fixed to one end of the housing 4 by a connecting screw, and the adjustment mechanism 10 is screwed into the other end of the housing 4 and abuts inside the spring box 3, and is used to adjust the compression amount of the spring 303 so as to achieve the purpose of adjusting the action point and reset point of the pressure switch. The micro switch 7 is fixed to the other end of the housing 4 by screws, and its contact button contacts the spring box 3, and the on-off state of the internal contacts can be changed as the spring box 3 moves.

[0047] To achieve protection, the mechanical pressure switch further includes a dust-proof pad 5 and a protective cover 6, and the dust-proof pad 5 and the protective cover 6 are fixed to one end of the housing 4 away from the step-down module 1. Further, it also includes a connector 9 which is fixed to the side of the housing 4 and feeds back the on-off state of the internal contacts of the micro switch 7 through a cable.

[0048] The working principle of the above mechanical pressure switch is as follows:

[0049] When the monitored air pressure is 0, under the action of the elastic member 106, the valve core 104 tightly presses on the valve seat 105, and the transition cavity 1104 is cut off from the intake cavity 1101; there is no air pressure acting on the S1 surface 1033 and S2 surface 1034 of the piston 103, so the transition cavity 1104 is communicated with the exhaust cavity 1102 and the acting cavity 1105, as Figure 3 shown, which is recorded as the initial state. At this time, the external atmospheric pressure acts on the air pressure sensing element 2, and the output state of the pressure switch is recorded as state O (the normally closed contact is closed and the normally open contact is open).

[0050] When the monitored air pressure is P0 (P0 > 0), P0 acts on the S2 surface 1034 of the piston 103 to generate a leftward thrust as Figure 2 shown (the diameter of the valve seat 105 is very small, so the rightward thrust generated by the pressure in the intake cavity 1101 through the valve core 104 is ignored), overcoming the spring force value f of the elastic member 106, so that the valve head 1031 of the piston 103 abuts on the valve core 104, thereby realizing the cut-off between the transition cavity 1104 and the exhaust cavity 1102; as the air pressure increases, the thrust continues to push the valve core 104 to move leftward, so that the valve core 104 disengages from the valve seat 105, and then realizes the conduction between the transition cavity 1104 and the intake cavity 1101. The pressure in the intake cavity 1101 enters the transition cavity 1104 and acts on the S1 surface 1033 of the piston 103 and generates asFigure 2 The reverse thrust shown to the right. When the value of the reverse thrust gradually increases to the value of the thrust minus the spring force value of the elastic member 106, the valve core 104 presses tightly against the valve seat 105, the transition chamber 1104 is cut off from the intake chamber 1101, and the intake chamber 1101 stops supplying gas to the transition chamber 1104. At this time, the valve head 1031 of the piston 103 still abuts against the valve core 104, and the transition chamber 1104 is still cut off from the exhaust chamber 1102. In this state, the gas pressure in the transition chamber 1104 and the acting chamber 1105 is P = P0·S2 / S1 - f / S1. When the monitored air pressure P0 increases, under the action of the thrust, the valve core 104 leaves the valve seat 105, and the intake chamber 1101 continues to supply compressed gas to the transition chamber 1104; when the monitored air pressure P0 decreases, the value of the reverse thrust is greater than the value of the thrust minus the spring force value of the elastic member 106. Under the action of the reverse thrust, the piston 103 moves to the right, and the transition chamber 1104 exhausts gas to the exhaust chamber 1102 until the value of the reverse thrust decreases to the value of the thrust minus the spring force value of the elastic member 106. When the air pressure P processed by the pressure reduction module 1 reaches the action value preset by the pressure switch, under the action of the air pressure sensing element 2, the push rod 8 pushes the spring seat 302 to compress the contact button of the micro switch 7, and the state of the micro switch 7 changes, as Figure 4 shown, denoted as the action state, and the output state of the pressure switch is denoted as state 1; when the monitored air pressure decreases, under the action of the force of the spring 303 in the spring box 3, the state of the micro switch 7 is reset, and the output state of the pressure switch returns to state 0.

[0051] After being processed by the pressure reduction module 1, the monitored pressure becomes P = P0·S2 / S1 - f / S1. Different pressure reduction ratios can be obtained by changing the sizes of S1 and S2; when increasing the force value of the elastic member 106, different pressure differences can be obtained.

[0052] In the above mechanical pressure switch, since the compressed gas pressure that causes the pressure switch to act or reset is processed by the pressure reduction module 1 for pressure reduction, compared with the pressure switch with a large range and a high set point before pressure reduction, using a pressure switch with a smaller range and a lower set point can effectively improve the control accuracy. The pressure reduction module 1 is placed in front of the air pressure sensing element 2 of the pressure switch, and the set point of the pressure switch is set for the pressure after being processed by the pressure reduction module 1. Therefore, the attenuation of the pressure reduction module 1 itself does not affect the accuracy of the pressure switch. The pressure reduction module 1 reduces pressure by means of air pressure balance, and its accuracy is little affected by the ambient temperature. Therefore, the influence of temperature change on the accuracy of the pressure switch can be reduced. The pressure switch is provided with a transition chamber 1104, which realizes the isolation of the monitored pressure from the actual contact pressure of the pressure switch, can discharge the moisture in the gas path, and reduces the requirement of the pressure switch for the quality of the medium.

[0053] In summary, the high-precision pressure switch of the present invention mainly consists of components such as a pressure reduction module 1, a pneumatic sensing element 2, a spring box 3, a housing 4, a dust-proof pad 5, a protective cover 6, a micro switch 7, a push rod 8, a sealing ring, a connector 9, an adjustment mechanism 10, and connecting screws. The pressure reduction module 1 and the protective cover 6 are respectively installed at both ends of the housing 4 through connecting screws. The spring box 3 and the pneumatic sensing element 2 are sequentially installed in the inner cavity of the housing 4. The pneumatic sensing element 2 converts the pressure information of the monitored medium into displacement information. The push rod 8 is placed between the pneumatic sensing element 2 and the spring box 3, and is used to transmit the displacement information of the pneumatic sensing element 2 to the spring box 3, and then to the micro switch 7. The micro switch 7 feeds back the state information of the monitored medium through the connector 9.

[0054] The pressure reduction module 1 mainly consists of parts such as a cover plate 101, a connecting seat 102, a piston 103, a valve core 104, a valve seat 105, an elastic member 106, a sealing ring, a K-shaped ring, and connecting screws. The valve seat 105 is press-fitted in the groove of the cover plate 101 with interference to form an air inlet cavity 1101. The elastic member 106 and the valve core 104 are placed in the air inlet cavity 1101. The piston 103 adopts a variable-diameter structure design and its core is through-hole, with an S1 surface 1033, an S2 surface 1034, a valve head 1031, and an exhaust groove 1032. It is placed in the inner cavity of the connecting seat 102, and forms an exhaust cavity 1102 with the exhaust port 1021 of the connecting seat 102, a balance cavity 1103 with the boss 1022 of the connecting seat 102, and a transition cavity 1104 with the cover plate 101 and the valve core 104. The piston 103 can move in the inner cavity of the mounting seat under the action of air pressure, and its valve head 1031 can change the on-off state between the air inlet cavity 1101 and the transition cavity 1104.

[0055] The balance cavity 1103 is directly connected to the air inlet cavity 1101 through a gas path to collect the inlet air pressure. The inlet air pressure acts on the S2 surface 1034 of the piston 103, pushing the valve core 104 away from the valve seat 105, and the air inlet cavity 1101 fills the transition cavity 1104 with air. The pressure in the transition cavity 1104 acts on the S1 surface 1033 of the piston 103. When the thrust generated by the pressure in the transition cavity 1104 acting on the S1 surface 1033 of the piston 103 is equal to the thrust generated by the pressure in the air inlet cavity 1101 acting on the S2 surface 1034 of the piston 103, under the action of the elastic member 106, the valve core 104 closes and the air inlet cavity 1101 stops filling the transition cavity 1104 with air. The pressure in the transition cavity 1104 is transported through the gas path to the acting cavity 1105 formed between the pneumatic sensing element 2, the pressure reduction module 1, the housing 4, and the sealing ring, and then the pressure after the pressure reduction of the pressure reduction module 1 acts on the pneumatic sensing element 2, the push rod 8, the spring seat 302, and the micro switch 7 until the output state of the pressure switch is changed.

[0056] The pressure reduction ratio or pressure difference of the pressure reduction module 1 of the present invention can be changed by adjusting the sizes of S1 and S2 and the force value of the elastic member 106.

[0057] It should be noted that the voltage reduction module 1 of the present invention is not limited to the fixed-ratio voltage reduction form shown in the figure, and can also be a fixed-difference voltage reduction form. Further, the voltage reduction ratio or voltage difference of the voltage reduction module 1 can also be adjusted to further achieve the purpose of adjusting the dead zone of the pressure switch (the pressure difference between the action point (corresponding to the alarm pressure) and the reset point (corresponding to the reset pressure) of the pressure switch). The connection method of the voltage reduction module 1 of the present invention is not limited to the scheme shown in the figure, and can also be located below the housing 4.

[0058] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0059] The above embodiments only represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be understood as a limitation to the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A high-precision mechanical pressure switch, characterized in that: include: An air pressure sensing element having a sensing surface at one end; The step-down module is disposed in front of the induction device and comprises: A cover plate having a groove on one side corresponding to the air pressure sensing element; A valve seat, which is press-fitted into the groove and forms an air inlet cavity with the cover plate; an elastic member, disposed in the air inlet cavity close to the cover plate; A valve core is placed in the air inlet cavity, one end of the valve core is against the elastic member, and the other end is pressed tightly against the valve seat; A connecting seat, located between the cover plate and the air pressure sensor element, connected to the cover plate, having a connecting seat inner cavity on one side corresponding to the cover plate, and connecting the connecting seat inner cavity with the atmosphere through an exhaust port; A piston is placed in the inner cavity of the connecting seat and is arranged opposite to the valve seat; it includes a valve head, an exhaust groove, S1 and S2 surfaces; the piston has a first end and a second end opposite to the first end, the center part of the first end protrudes outward to form the valve head, the valve head penetrates the valve seat and abuts against the valve core, and the surface of the non-valve head part of the first end opposite to the valve seat is the S1 surface; the center part of the second end protrudes outward and is inserted into the inner cavity of the connecting seat, and the surface of the non-center protruding part of the second end opposite to the connecting seat is the S2 surface; the area of ​​the S1 surface is larger than the area of ​​the S2 surface; one end of the exhaust groove is connected to the exhaust port, and the other end penetrates the valve head and is connected to the valve core; An exhaust chamber is formed between the piston and the exhaust port, a balance chamber is formed between the S2 surface and the connecting seat, a transition chamber is formed between the S1 surface and the cover plate, the valve core and the valve seat; and an action chamber is formed between the sensing surface and the connecting seat.

2. The mechanical pressure switch according to claim 1, characterized in that: The piston moves in the inner cavity of the connecting seat under the action of air pressure, and changes the on-off state between the air inlet chamber and the transition chamber through the valve head; the balance chamber is connected with the air inlet chamber through an air path to collect the air inlet pressure of the pressure switch; the air inlet chamber pressure acts on the S2 surface; the transition chamber pressure acts on the S1 surface; the transition chamber is connected with the action chamber through an air path; and the exhaust chamber is connected to the atmosphere.

3. The mechanical pressure switch according to claim 1, characterized in that: The cover plate and the connecting seat are sealed by a sealing ring; the exhaust chamber and the balancing chamber, and the balancing chamber and the transition chamber are sealed by K-shaped rings respectively.

4. The mechanical pressure switch according to claim 1, characterized in that: The air pressure sensing element comprises a bellows and a flange, one end of the bellows is connected to the flange, and the other end of the bellows defines the sensing surface.

5. The mechanical pressure switch according to claim 1, characterized in that: It also includes a shell, the shell has a shell inner cavity, the air pressure sensor element is arranged in the shell inner cavity; the shell is connected to the connecting seat.

6. The mechanical pressure switch according to claim 5, characterized in that: It also includes a spring box arranged in the inner cavity of the shell, and a push rod arranged between the air pressure sensor element and the spring box; under the thrust of the spring box, one end of the push rod can be against the sensing surface; the other end of the push rod is connected to the spring box.

7. The mechanical pressure switch according to claim 6, characterized in that: The spring box includes a guide sleeve, a spring seat, a spring, an adjustment seat, and a fine-tuning nut; the guide sleeve is fixed to the outer ring surface of the spring seat; the spring is placed between the spring seat and the adjustment seat; the fine-tuning nut is fixed to the spring seat through a thread and is used to adjust the pre-compression amount of the micro switch contact button.

8. The mechanical pressure switch according to claim 7, characterized in that: It also includes an adjustment mechanism, which is screwed into the housing from one end away from the voltage reduction module and abuts against the adjustment seat.

9. The mechanical pressure switch according to claim 5, characterized in that: It also includes a dustproof pad and a protective cover, wherein the dustproof pad and the protective cover are fixed to one end of the shell away from the step-down module.

10. The mechanical pressure switch according to claim 7, characterized in that: It also includes a connector, which is fixed on the side of the shell and feeds back the on-off state of the internal contacts of the micro switch through a cable.

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