Pressure relief valve for coffee machine and coffee machine

Abstract

The present invention relates to a pressure relief valve for a coffee machine and the coffee machine thereof, and relates to the technical field of pressure relief valve structures. The pressure relief valve includes a valve body provided with a first joint for communicating with the outside world and a second joint for communicating with a water system. The valve body includes a valve core, a valve stem, and a spring. The valve core is located on one side of the first joint, and the valve stem is located below the valve core and on one side of the second joint. One end of the spring abuts against the upper portion of the valve body, and the other end of the spring abuts against the valve core. When the water system is in three different pressure states, the position state between the valve stem and the valve core controls whether the water system is connected to the outside atmosphere. The pressure relief valve for a coffee machine and the coffee machine thereof disclosed by the present invention can solve the application problem that the current water system of a coffee machine needs to provide low-pressure exhaust and overload pressure relief mechanisms in the water system, resulting in a complex overall structure.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure relief valve structures, and in particular to a pressure relief valve for a coffee machine and the coffee machine. Background Art

[0002] During the low-pressure water replenishment stage of the coffee machine's water system, when the water circuit is in a completely closed state, the water pump needs to use negative pressure to extract water from the water tank to the heating module. At this time, the vacuum resistance formed in the closed pipeline will significantly increase the load on the water pump, resulting in a decrease in water replenishment efficiency and even intermittent water flow, affecting the stability of coffee making. At the same time, if the pressure in the water system increases abnormally due to heating expansion, pipe blockage or solenoid valve failure, and exceeds the material tolerance threshold, it may cause safety hazards such as pipe rupture and seal failure. At the very least, water leakage will damage the equipment, and at worst, high-temperature and high-pressure steam splashing will cause scalding risks. To deal with these two types of problems, traditional designs often require independent low-pressure exhaust valves and overload pressure relief valves to be set in the water circuit: the former discharges the pipeline gas to eliminate negative pressure resistance during the low-pressure stage, and the latter quickly relieves pressure at high pressure to ensure safety. However, the dual-valve discrete layout not only increases the complexity of the water path structure, requiring additional interfaces, seals, and assembly processes, but also leads to redundant control logic and increased maintenance costs. Moreover, the coordinated errors among multiple components may reduce system reliability, hindering the further compactness of the coffee machine structure. Summary of the Invention

[0003] In order to overcome the defects of the prior art, the present invention proposes a pressure relief valve for a coffee machine and a coffee machine thereof, which can solve the application problem that the current coffee machine water system needs to set low-pressure exhaust and overload pressure relief mechanisms in the water channel respectively, resulting in a complex overall structure.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] The present invention provides a pressure relief valve for a coffee machine, including a valve body, which is provided with a first joint connected to the outside atmosphere and a second joint connected to the water system; a valve core, a valve stem and a spring are provided in the valve body, the valve core is located on one side of the first joint, the valve stem is located below the valve core and on one side of the second joint, one end of the spring is against the upper part of the valve body, and the other end of the spring is against the valve core, when the water system is below the first pressure relief pressure, the valve stem and the valve core are separated to form a first pressure relief channel, so that the water system is connected to the outside atmosphere, when the water system is between the first pressure relief pressure and the second pressure relief pressure, the valve stem and the valve core are fitted together, so that the water system is isolated from the atmospheric pressure, and when the water system is above the second pressure relief pressure, the valve stem lifts the valve core to form a second pressure relief channel, so that the water system is connected to the outside atmosphere.

[0006] The preferred technical solution of the present invention is that the valve body includes an upper chamber and a lower chamber, the valve core is located in the upper chamber, the valve stem is located in the lower chamber, and a limiting portion is provided between the upper chamber and the lower chamber to prevent the valve core from moving into the lower chamber.

[0007] A preferred technical solution of the present invention is that a valve core sealing ring is provided between the valve core and the interior of the valve body.

[0008] A preferred technical solution of the present invention is that the middle portion of the valve core is in a communicating structure, and the rod body of the valve stem passes through the middle portion of the valve core.

[0009] A preferred technical solution of the present invention is that the upper cross-section of the valve stem is a regular polygon, the inner cross-section of the valve core is a circle, and the number of sides of the regular polygon is 3-6.

[0010] A preferred technical solution of the present invention is that an arc-shaped air passage groove is provided at the lower portion of the valve stem.

[0011] The preferred technical solution of the present invention is that a valve stem sealing ring is sleeved on the rod body of the valve stem.

[0012] The preferred technical solution of the present invention is that an axially movable valve cover is provided on the upper portion of the valve body, one end of the spring abuts against the bottom of the valve cover, and the other end of the spring abuts against the valve core.

[0013] A preferred technical solution of the present invention is that the valve cover and the valve body are threadedly connected.

[0014] The present invention provides a coffee machine, comprising the pressure relief valve of the above technical solution.

[0015] Beneficial effects of the present invention:

[0016] The present invention provides a pressure relief valve for a coffee machine and the coffee machine thereof. This pressure relief valve organically integrates the functions of low-pressure exhaust and overload pressure relief into a single device. The core of the pressure relief valve lies in the coordinated action of the valve body, valve core, valve stem, and spring. Below a first pressure relief pressure, the water system achieves low-pressure relief through a path from the second connector to the valve body cavity and then to the first connector. When the system pressure rises to a range between the first and second pressure relief pressures, the valve stem moves upward under pressure to form a sealed contact with the bottom of the valve core, blocking the water system from the atmosphere. When the pressure exceeds the second pressure relief pressure, the internally generated upward force completely overcomes the spring pressure and the deadweight of the valve stem, pushing the valve core upward and away from the inner surface of the valve body, forming a new second pressure relief channel between the outer periphery of the valve core and the inner wall of the valve body, thereby achieving rapid release of high-pressure gas. This stepped pressure response mechanism creatively integrates the pressure relief requirements of two different pressure thresholds into an overall mechanism through the linear compression characteristics of a single spring and the differential coordination of the valve core and valve stem, effectively solving the application problem of the current coffee machine water system that requires the installation of low-pressure exhaust and overload pressure relief mechanisms in the water path separately, resulting in a complex overall structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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.

[0018] Figure 1 This is a perspective view of a pressure relief valve for a coffee machine according to a first embodiment of the present invention;

[0019] Figure 2 A top view of a pressure relief valve for a coffee machine according to a first embodiment of the present invention;

[0020] Figure 3 This is an exploded view of a pressure relief valve for a coffee machine according to a first embodiment of the present invention;

[0021] Figure 4 For low pressure system Figure 2 Cross-sectional view along the AA direction and gas flow schematic diagram;

[0022] Figure 5 For medium voltage system Figure 2 Cross-sectional view along the AA direction and gas flow schematic diagram;

[0023] Figure 6 For high pressure system Figure 2 Cross-sectional view along the AA direction and gas flow schematic diagram;

[0024] Figure 7 This is a three-dimensional diagram of a valve body according to a first embodiment of the present invention;

[0025] Figure 8 A three-dimensional diagram of a valve core according to a first embodiment of the present invention;

[0026] Figure 9 A three-dimensional diagram of a valve stem according to a first embodiment of the present invention;

[0027] Figure 10 This is a front view of the valve stem of the second embodiment of the present invention;

[0028] Figure 11 A three-dimensional diagram of a valve stem according to a second embodiment of the present invention;

[0029] Figure 12 This is a top view of the valve stem and valve core after assembly according to the second embodiment of the present invention.

[0030] In the picture:

[0031] 1-valve body; 11-first joint; 12-second joint; 13-upper chamber; 14-lower chamber; 2-valve core; 3-valve stem; 31-stem body; 32-air groove; 4-spring; 5-valve core sealing ring; 6-valve stem sealing ring; 7-valve cover. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0033] Example 1

[0034] This embodiment provides a pressure relief valve for a coffee machine, such as Figure 1-9 As shown, it includes a valve body 1, which is provided with a first joint 11 connected to the outside atmosphere and a second joint 12 connected to the water system; a valve core 2, a valve stem 3 and a spring 4 are provided in the valve body 1, the valve core 2 is located on one side of the first joint 11, the valve core 2 is confined to the upper area of ​​the valve body, the valve stem 3 is located below the valve core 2 and on one side of the second joint 12, and the valve stem 3 falls vertically under the action of gravity and breaks away from the contact with the valve core 2.

[0035] One end of the spring 4 abuts against the upper part of the valve body 1, and the other end of the spring 4 abuts against the valve core 2. When the water system is below the first pressure relief pressure, since the valve core 2 is confined to the upper area inside the valve body and the valve stem 3 falls vertically under the action of gravity, the valve stem 3 and the valve core 2 separate to form a first pressure relief channel, which connects the water system to the outside atmosphere. When the water system is between the first pressure relief pressure and the second pressure relief pressure, the valve stem 3 and the valve core 2 fit together, so that the water system is isolated from the atmospheric pressure. When the water system is above the second pressure relief pressure, the valve stem 3 clings to and lifts up the valve core 2, forming a second pressure relief channel, which connects the water system to the outside atmosphere. The technical solution of this embodiment integrates the two functions of low-pressure exhaust and overload pressure relief into a single device through the innovative design of the internal structure of the valve body. Its core lies in the synergistic mechanism of the valve body, valve core, valve stem and spring. The valve body, as the functional carrier, features a first connector that directly connects to the atmosphere, while a second connector forms a pressure-transmitting interface with the water system. Pressure interaction between the two occurs through the valve's inner cavity. The valve core, the primary pressure-responsive actuator, is controlled by both spring pressure and system pressure. The spring's upper end rigidly contacts the top of the valve body, while its lower end exerts a continuous downward force on the valve core, forming the basis for the structure's initial mechanical equilibrium. The valve stem, located below the valve core, near the water system, serves as the secondary pressure-responsive actuator. Its position is controlled by both its own gravity and system pressure. The shape of its top end forms a complementary contact surface with the bottom of the valve core, and the state of these two determines the opening and closing of the pressure channel. During low-pressure conditions (below the first relief pressure), the water system pressure is insufficient to overcome the weight of the valve stem. The valve core remains in an elevated position, creating a gap between the top of the stem and the bottom of the valve core, forming the primary pressure relief channel. This allows low-pressure release of gas from the water system via the second connector, then the valve body, and finally the first connector. When system pressure rises to the medium pressure stage (between the first and second relief pressures), the valve stem, driven by the water system pressure, moves upward and forms a sealing contact with the bottom of the valve plug, forming a stem-spool combination that blocks the water system from the atmosphere. However, the spring compression remains constant, maintaining the seal and allowing the system to enter normal operation. When the water system pressure rises to the high pressure stage (above the second relief pressure), the internal upward force completely overcomes the spring pressure and the deadweight of the valve stem and other components. The stem and valve plug are lifted, pushing the entire valve plug upward and away from the inner surface of the valve body, thus forming a second relief channel and enabling rapid release of high-pressure gas. This stepped pressure response mechanism, through the linear compression characteristics of a single spring, the differential action of the valve plug and stem, and the spatial layout of the valve body flow path, creatively integrates the pressure relief requirements of two different pressure thresholds into a continuous action process. This ensures precise exhaust requirements in the low-pressure stage while meeting the safety protection requirements during high-pressure overload, significantly improving the functional integration and operating adaptability of the pressure relief device.

[0036] Preferably, the valve body 1 includes an upper chamber 13 and a lower chamber 14, the valve core 2 is located in the upper chamber 13, the valve stem 3 is located in the lower chamber 14, and a limiting portion is provided between the upper chamber 13 and the lower chamber 14 to prevent the valve core 2 from moving into the lower chamber 14. In this embodiment, a narrowing structure from top to bottom is provided between the upper chamber 13 and the lower chamber 14, thereby playing the role of limiting the valve core. The interior of the valve body is divided into an upper chamber and a lower chamber, and the movement areas of the valve core and the valve stem are isolated by the limiting portion. This structural innovation significantly improves the accuracy and reliability of the pressure relief action. The upper chamber serves as an independent movement space for the valve core, which can prevent impurities in the water system from interfering with the movement trajectory of the valve core, while the lower chamber directly senses the pressure changes in the water system through the valve stem, forming a modular control of pressure zoning. Furthermore, the sub-chamber design optimizes fluid dynamics. The connection path between the upper chamber and the first connector is shortened, accelerating low-pressure exhaust efficiency. The lower chamber is directly connected to the waterway via the second connector, reducing pressure transmission lag and making the system more responsive. This design, through physical isolation and functional zoning, reduces the risk of interference between the valve core and valve stem, while also improving the stability of the pressure relief threshold.

[0037] Preferably, a valve core sealing ring 5 is provided between the valve core 2 and the inside of the valve body 1. In this embodiment, the valve core sealing ring 5 is sleeved on the valve core 2. Adding a valve core sealing ring between the valve core and the inner wall of the valve body is a key improvement to solve the problem of leakage in the traditional pressure relief valve. In the low-pressure exhaust stage, the elastic fit between the valve core sealing ring and the valve body can block unexpected leakage from other paths, so that it is discharged according to the first pressure relief channel originally designed; in the high-pressure pressure relief stage, the valve core sealing ring is lifted up along with the valve core, so that the sealing effect is released and the second pressure relief channel is opened. The material of the valve core sealing ring can be selected from fluororubber or silicone, and it is necessary to take into account both high temperature resistance and elastic modulus to adapt to the frequent thermal cycle conditions of the coffee machine. It should be supplemented that the interior of the valve body 1 can also be provided with a similar structure for the valve core sealing ring 5 to be sleeved on, instead of being sleeved on the valve core 2, so as to achieve sealing between the valve core 2 and the valve body 1.

[0038] Preferably, the middle part of the valve core 2 is a connected structure, and the rod body 31 of the valve stem 3 passes through the middle part of the valve core 2. The through-type flow channel in the middle of the valve core and the through-type valve stem cooperate to reconstruct the pressure transmission path and mechanical linkage logic. In the traditional design, the separate structure of the valve core and the valve stem requires the transmission of displacement through a complex lever, while this solution directly passes through the middle of the valve core through the valve stem, converting the top thrust of the water pressure on the valve stem into the axial displacement of the valve core, greatly simplifying the force transmission chain. The connected structure of the valve core allows the pressure of the lower chamber to act directly on the bottom of the valve core through the hollow channel, forming a direct confrontation with the spring pressure, eliminating the force loss in the intermediate link. This design not only improves the sensitivity of the response action, but also reduces the number of parts and the failure rate through structural integration.

[0039] Furthermore, a valve stem sealing ring 6 is sleeved on the rod body 31 of the valve stem 3. The valve stem sealing ring is sleeved on the valve stem rod body, and its function is to combine dynamic sealing and guiding functions. When the valve stem moves up and down with the pressure change, the valve stem sealing ring maintains close contact with the inner wall of the valve body, blocking the cross leakage between the lower chamber and the upper chamber, and ensuring the independence of the pressure sensing signal. At the same time, the radial preload of the sealing ring has a self-centering effect on the valve stem, maintaining stability in use. It should be noted that the interior of the valve core 2 can also be provided with a similar structure for the valve core sealing ring 5 to be sleeved on, instead of being sleeved on the valve stem 3, thereby achieving sealing between the valve core 2 and the valve body 1.

[0040] Preferably, a curved air passage groove 32 is provided at the lower portion of the valve stem 3. Providing a curved air passage groove at the lower portion of the valve stem achieves a systematic improvement in pressure relief performance. This innovative design significantly improves airflow characteristics through a streamlined structure. The continuous curvature transition of the curved groove effectively avoids the airflow separation phenomenon common in traditional right-angle grooves, making the gas flow smoother and more stable. During the pressure relief process, the curved structure can guide the pressure wave to diffuse evenly, preventing local overpressure from impacting the sealing surface, while also improving overall pressure relief efficiency.

[0041] Preferably, an axially movable valve cover 7 is provided on the upper part of the valve body 1, one end of the spring 4 is against the bottom of the valve cover 7, and the other end of the spring 4 is against the valve core 2. An axial adjustment structure is adopted between the valve cover and the valve body to make the spring pressure of the valve body adjustable. During production, the corresponding pressure relief parameters can be determined according to the actual spring structural parameters and the structural parameters inside the valve body. This design allows the same valve body to quickly adapt to the pressure requirements of various coffee machine models by adapting springs of different specifications or adjusting the position of the valve cover, significantly improving the versatility of parts. The adjustable valve cover also simplifies the maintenance process. Users can complete pressure calibration without disassembling the entire valve body, reducing after-sales costs. Furthermore, the valve cover 7 and the valve body 1 are threaded. This solution is simple and direct. By rotating the valve cover to change the screwing depth between it and the valve body, the initial compression of the spring can be accurately adjusted, thereby flexibly setting the pressure relief parameters.

[0042] According to the technical solution of the above embodiment, the parameter design of the pressure relief calculation is briefly described below, using Creo modeling design:

[0043] Requirements: 3±0.5bar pressure relief (ignoring friction), exhaust sealing pressure 0.1bar, that is, the exhaust function is closed at 0.1bar.

[0044] Valve stem: material copper H59, weight 1.9g; valve stem sealing ring: material fluororubber, weight 0.1g;

[0045] Valve core: material copper H59, weight 5.2g; valve core sealing ring: material fluororubber, weight 0.2g;

[0046] S (cross-sectional force area of ​​the valve stem at low pressure stage) = 8mm²;

[0047] S (the sum of the cross-sectional force-bearing areas of the valve stem and valve core fitting under medium pressure) = 65 mm²;

[0048] Spring: The natural state height is h=14mm. When the valve cover is screwed to the upper limit, the spring installation height is h=12mm, and F (upper limit elastic force) = 10.5N. When the valve cover is screwed to the lower limit, the spring installation height is h=9mm, and F (lower limit elastic force) = 25.5N.

[0049] 1. Exhaust status in low pressure stage:

[0050] ①G (valve stem + valve stem sealing ring) = m (valve stem + valve stem sealing ring) g = 0.02N;

[0051] Where G is gravity, m is mass, and g is acceleration due to gravity, and the same applies below.

[0052] ②When F (valve stem is subjected to upward pressure) = G (valve stem + valve stem sealing ring) = 0.02N,

[0053] P (line pressure) = F (upward pressure on the valve stem) / S (cross-sectional force area of ​​the valve stem at low pressure) = 0.02N / 8mm² = 0.025bar;

[0054] Where F is pressure, P is pressure intensity, and g is acceleration due to gravity, and the same applies below.

[0055] ③ When F (upward pressure on the valve stem) is less than G (valve stem + valve stem sealing ring), that is, P (line pressure) is less than 0.025 bar, the valve stem and the valve stem sealing ring are in a dropped state. At this time, air can pass through the clearance between the valve stem and the valve core to achieve low-pressure exhaust.

[0056] 2. Normal working state in the medium pressure stage (when the valve cover is screwed to the upper limit):

[0057] ①G (valve core + valve core sealing ring + valve stem + valve stem sealing ring) = 0.07N;

[0058] ② When F (upward pressure on the valve stem and valve core) = G (valve core + valve core seal + valve stem + valve stem seal) + F (upper limit spring force) = 10.5N + 0.07N = 10.57N, P (line pressure) = F (upward pressure on the valve stem and valve core) / S (sum of the cross-sectional force-bearing areas of the valve stem and valve core under medium pressure) ≈ 1.6 bar;

[0059] ③ When F (upward pressure on the valve stem and valve core) > G (valve stem + valve stem sealing ring) and F (upward pressure on the valve stem and valve core) < G (valve core + valve core sealing ring + valve stem + valve stem sealing ring) + F (upper limit elastic force), that is, 0.025bar < P (pipeline pressure) < 1.6bar, the valve stem and valve core are in a sealed state, and the valve core and valve body are also in a sealed state. At this time, the pipeline is working normally.

[0060] 3. High pressure stage pressure relief state (when the valve cover is screwed to the upper limit):

[0061] When F (upward pressure on the valve stem and valve core) > G (valve core + valve core sealing ring + valve stem + valve stem sealing ring) + F (upper limit elastic force), that is, P (line pressure) > 1.6 bar, the valve core is lifted and the pressure can be relieved through the clearance between the valve core and the valve body.

[0062] 4. Normal working state in the medium pressure stage (when the valve cover is screwed to the lower limit):

[0063] ①G (valve core + valve core sealing ring + valve stem + valve stem sealing ring) = 0.07N;

[0064] ② When F (upward pressure on the valve stem and valve core) = G (valve core + valve core seal + valve stem + valve stem seal) + F (lower limit spring force) = 25.57N, P (line pressure) = F (upward pressure on the valve stem and valve core) / S (sum of the cross-sectional force-bearing areas of the valve stem and valve core at medium pressure) ≈ 3.9bar;

[0065] ③ When F (upward pressure on the valve stem and valve core) > G (valve stem + valve stem sealing ring) and F (upward pressure on the valve stem and valve core) < G (valve core + valve core sealing ring + valve stem + valve stem sealing ring) + F (lower limit elastic force), that is, 0.025bar < P (pipeline pressure) < 3.9bar, the valve stem and valve core are in a sealed state, and the valve core and valve body are also in a sealed state. At this time, the pipeline is working normally.

[0066] 5. Pressure relief state in high pressure stage (when the valve cover is screwed to the lower limit):

[0067] When F (upward pressure on the valve stem and valve core) > G (valve core + valve core sealing ring + valve stem + valve stem sealing ring) + F (lower limit elastic force), that is, P (line pressure) > 3.9 bar, the valve core is lifted and the pressure can be relieved through the clearance between the valve core and the valve body.

[0068] Example 2

[0069] This embodiment provides a pressure relief valve for a coffee machine, such as Figure 10-12As shown, the difference between this embodiment and the pressure relief valve of Example 1 lies in that the upper cross-section of the valve stem is a regular polygon, that is, the cross-section of its stem body 31 is a regular polygon, while the internal cross-section of the valve core 2 is a circle, with 3-6 sides. The core of this preferred solution lies in the use of a regular polygon with 3-6 sides in the upper cross-section of the valve stem, which forms an internal centrosymmetric gap with the internal circular cross-section of the valve core. Compared with the traditional circular-circular contact structure of Example 1, this design achieves breakthrough improvements in air discharge characteristics, anti-scaling performance, and motion stability. Traditional full-circumferential contact structures are prone to forming linear scale deposition zones in hard water environments due to the high-pressure adsorption effect of the continuous contact surface. This solution reconstructs the contact pattern into discrete point contacts (i.e., the vertices of the regular polygon are tangent to the inner wall of the circle). By reducing the effective contact area and concentrating the contact stress, the scale nucleation sites are shifted from the continuous contact zone to the non-contact gap region. This design significantly reduces the probability of scale deposition in the contact point region while utilizing the enhanced shear force of the fluid within the gap channel to achieve dynamic flushing of microscopic scale particles. This active anti-scaling mechanism effectively solves the valve core jamming problem caused by scale accumulation in traditional structures. Furthermore, the small contact surface reduces friction between the valve core and the valve stem, and the reduction in scale further reduces friction between the two. The sliding interface between the valve core and the valve stem maintains a low-friction state over a long period of time, avoiding the nonlinear increase in friction coefficient caused by scale accumulation in traditional structures and significantly improving responsiveness. In this embodiment, the regular polygon of the upper cross-section of the valve stem has six sides.

[0070] Example 3

[0071] A coffee machine provided in this embodiment includes a pressure relief valve as in the first embodiment. The coffee machine also has the advantages of simple structure and significant effect while ensuring the precise exhaust requirements in the low-pressure stage and meeting the safety protection requirements during high-pressure overload.

[0072] The present invention is described through preferred embodiments. Those skilled in the art will appreciate that various modifications or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. The present invention is not limited to the specific embodiments disclosed herein; other embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A pressure relief valve for a coffee machine, characterized by: The invention comprises a valve body (1), wherein the valve body (1) is provided with a first joint (11) for communicating with the outside atmosphere and a second joint (12) for communicating with the water system; a valve core (2), a valve stem (3) and a spring (4) are provided in the valve body (1), wherein the valve core (2) is located on one side of the first joint (11), the valve stem (3) is located below the valve core (2) and on one side of the second joint (12), one end of the spring (4) is against the upper part of the valve body (1), and the other end of the spring (4) is against the valve core (2); The valve body (1) comprises an upper chamber (13) and a lower chamber (14); The valve core (2) is located in the upper chamber (13), the valve stem (3) is located in the lower chamber (14), and a limit portion is provided between the upper chamber (13) and the lower chamber (14) to prevent the valve core (2) from moving into the lower chamber (14); A valve core sealing ring (5) is provided at a limiting portion between the valve core (2) and the interior of the valve body (1); the middle portion of the valve core (2) is in a communicating structure; the stem of the valve stem (3) passes through the middle portion of the valve core (2); a valve stem sealing ring (6) is sleeved on the stem (31) of the valve stem (3); a gap is formed between the stem (31) of the valve stem (3) and the middle portion of the valve core (2); the gap constitutes a first pressure relief channel, and the first pressure relief channel is sealed by the valve stem sealing ring (6); When the water system is below the first pressure relief pressure, the valve stem sealing ring (6) of the valve stem (3) and the valve core (2) are separated, and the first pressure relief channel is opened, so that the water system is connected to the outside atmosphere. When the water system is between the first pressure relief pressure and the second pressure relief pressure, the valve stem (3) and the valve core (2) are fitted together through the valve stem sealing ring (6), so that the water system is isolated from the atmospheric pressure. When the water system is above the second pressure relief pressure, the valve stem (3) lifts the valve core (2), pushing the valve core (2) to move upward as a whole and away from the limiting portion of the valve body (1), forming a new second pressure relief channel between the outer periphery of the valve core (2) and the inner wall of the valve body (1), realizing the rapid discharge of high-pressure gas, so that the water system is connected to the outside atmosphere.

2. The pressure relief valve according to claim 1, characterized in that The upper cross section of the valve stem (3) is a regular polygon, the inner cross section of the valve core (2) is a circle, and the number of sides of the regular polygon is 3-6.

3. The pressure relief valve according to claim 1, characterized in that The lower part of the valve stem (3) is provided with an arc-shaped air passage groove.

4. The pressure relief valve according to claim 1, characterized in that: An axially movable valve cover (7) is provided on the upper portion of the valve body (1); One end of the spring (4) abuts against the bottom of the valve cover (7), and the other end of the spring (4) abuts against the valve core (2).

5. The pressure relief valve according to claim 4, characterized in that: The valve cover (7) and the valve body (1) are threadedly connected.

6. A coffee machine, characterized in that: Comprising the pressure relief valve according to any one of claims 1 to 5.

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