Pre-loaded check valve assembly and all-plastic pressing pump comprising same

Abstract

A pre-loaded check valve assembly and an all-plastic pressing pump comprising the pre-loaded check valve assembly. The pre-loaded check valve assembly is arranged in the all-plastic pressing pump (1), and comprises a piston rod (20), a piston head (30), a piston (40), and one or more elastic pre-load elements (21). A first sealing portion and a second sealing portion are formed between the piston (40) and the piston head (30) or the piston rod (20), and the second sealing portion has a height in the axial direction of the all-plastic pressing pump (1). When the piston (40) is displaced upward relative to the piston head (30), the first sealing portion opens first, and after the upward displacement distance of the piston (40) relative to the piston head (30) reaches or exceeds the height of the second sealing portion, the second sealing portion opens. The pre-loaded check valve assembly and the all-plastic pressing pump comprising the pre-loaded check valve assembly can prevent the elastic pre-load elements from creeping under long-term compression, while ensuring that a product is pumped outward at a predetermined pressure.

Description

A pre-pressurized check valve assembly and an all-plastic push pump including the pre-pressurized check valve assembly. Technical Field

[0001] This application relates to the field of packaging liquid or semi-liquid products, specifically to all-plastic pumps installed on product containers, and particularly to the design of a pre-pressure check valve in such all-plastic pumps. Background Technology

[0002] Press pumps are widely used in the daily chemical, food, and pharmaceutical industries to dispense liquid or semi-liquid products from containers for consumer use. To improve pumping efficiency or to achieve product atomization, some types of press pumps, such as spray pumps, incorporate a pre-pressurization mechanism. This mechanism presses against a piston, sealing the piston and piston head. The seal is released only when the product pressure in the pump exceeds the pressing force applied to the piston by the pre-pressurization mechanism, allowing the product to be pumped out. This ensures the pumped product has the required pressure, thereby improving pumping efficiency and enabling atomization and other desired effects.

[0003] Traditional push-button pumps use small metal springs as the pre-compression mechanism. However, to meet increasingly stringent environmental requirements, all-plastic pumps are becoming more prevalent. All-plastic pumps use plastic materials to construct the pre-compression mechanism. However, during use, it has been found that plastic pre-compression mechanisms exhibit several problems. For example, the elasticity of a plastic pre-compression mechanism is weaker than that of a metal spring, resulting in a less effective pre-compression of the piston. Furthermore, plastic pre-compression mechanisms are more prone to creep after prolonged pressure, leading to a weakening or even loss of elasticity, thus diminishing or ultimately eliminating the pre-compression function. In specific applications such as spray pumps, this manifests as the formation of large droplets at the beginning and end of the dispensing of atomized product.

[0004] Therefore, in the field of press pumps, there is a need for further improvements to the press pump structure to solve technical problems such as insufficient pumping pressure and incomplete atomization of products resulting in large droplets due to the weak or lost elasticity of the plastic pre-compression mechanism. Summary of the Invention

[0005] This application is made to solve the technical problems existing in the prior art described above. The purpose of this application is to provide a pre-pressure check valve assembly for a push pump, and further to provide an all-plastic push pump including the pre-pressure check valve assembly.

[0006] This application provides a pre-pressure check valve assembly disposed in an all-plastic push-pump, including a piston rod, a piston head, and a piston. The piston head and piston rod are fixedly connected together, and the piston is sleeved on the piston head. The pre-pressure check valve assembly also includes an elastic pre-pressure member disposed on one of the piston, piston head, and piston rod. In this pre-pressure check valve assembly, a first sealing portion is formed between the piston and the piston rod or piston head, and a second sealing portion is also formed between the piston and the piston rod or piston head. The second sealing portion has a height along the axial direction of the all-plastic push-pump. The first and second sealing portions are configured such that when the piston moves upward relative to the piston head, the first sealing portion opens first, and the second sealing portion opens after the distance the piston moves upward relative to the piston head reaches or exceeds the height of the second sealing portion.

[0007] With the pre-pressure check valve assembly described above, in the initial stage of the piston's upward movement relative to the piston head, the first sealing part opens first, while the second sealing part remains sealed. Only after the piston has moved upward by a distance equal to or greater than the height of the second sealing part does the second sealing part open, at which point the pre-pressure check valve assembly fully opens. Therefore, in the non-use state, the elastic pre-pressure member can be in a fully relaxed or relatively relaxed state, and only during the pressing process does the elastic pre-pressure member transition from the relaxed state to the loaded state. Furthermore, during the pressing process, the elastic pre-pressure member is gradually subjected to pressure, and the pre-pressure check valve assembly fully opens only after a certain amount of pressure has accumulated in the elastic pre-pressure member. This solves the problem of creep caused by prolonged pressure on the elastic pre-pressure member, while still ensuring that the product is pumped out at a predetermined pressure.

[0008] Additionally, at the end of pumping, the piston moves downward relative to the piston head, causing the second sealing part to form a seal first. This creates a negative pressure in the pump, which draws back the residual droplets in the nozzle of the pump head, preventing large droplets from falling at the end of pumping.

[0009] In one specific structure, the piston has an outer ring and an inner ring. The lower end of the inner ring has a first inclined surface. The piston head includes a sealing sleeve, the lower end of which has a second inclined surface. The first inclined surface can mate with the second inclined surface to form a first sealing portion. In this structure, the first sealing portion can be opened first during pumping.

[0010] Regarding the second sealing part, in one embodiment, the sealing sleeve extends downward, and the outer side of the sealing sleeve can cooperate with the inner side of the piston inner ring to form the second sealing part.

[0011] In another alternative embodiment, the sealing sleeve extends upward, forming a gap between the sealing sleeve and the piston head body, the gap accommodating the inner ring, with a second bevel formed at the bottom of the gap. The inner surface of the piston head sleeve mates with the outer surface of the inner piston ring to form a second seal.

[0012] Alternatively, in another alternative embodiment, the piston has an outer ring and an inner ring, the lower end of which is formed with a first bevel. The piston head includes a sealing sleeve, the inner side of which is formed with a second bevel. The first bevel can mate with the second bevel to form the first sealing portion. Furthermore, the second sealing portion can be formed by mates between the inner surface of the inner ring and the outer surface of the piston rod.

[0013] In addition, both the first sealing part and the second sealing part can be formed between the piston and the piston rod.

[0014] Preferably, an inner column is formed inside the sealing sleeve. This inner column helps to reduce the dead volume area in the pump, thereby reducing the number of times the pump needs to be pneumatically compressed during use.

[0015] In one specific structure, the elastic preload element includes multiple elastic strips.

[0016] Preferably, the elastic strips are formed in a "J" shape. Furthermore, these elastic strips can be arranged at equal intervals in the circumferential direction. Of course, other numbers and shapes of elastic strips are also within the scope of this application, and the spacing between the elastic strips can also be varied.

[0017] Preferably, at least one liquid guiding groove is formed on the body of the piston rod, the liquid guiding groove extends along the axial direction of the piston rod, and the liquid guiding groove cooperates with the piston rod inner hole to form a channel for product to flow through.

[0018] Preferably, the piston rod and piston head are formed integrally.

[0019] This application also relates to an all-plastic push-button pump, which includes a pressure head, a toothed sleeve, and a cylinder, with the toothed sleeve and the cylinder fixedly connected together. The all-plastic push-button pump further includes a pre-pressurization check valve assembly as described above, wherein a piston rod is connected to the lower part of the pressure head, the piston is located inside the cylinder, and it is in a sealing fit with the inner surface of the cylinder. Attached Figure Description

[0020] The accompanying drawings illustrate a non-limiting preferred embodiment of the invention, and the features and advantages of the invention become more apparent when viewed in conjunction with the drawings. Wherein:

[0021] Figure 1 shows a cross-sectional view of a push-button pump according to a first embodiment of this application, wherein the push-button pump is in an upper standby state.

[0022] Figure 2 shows another cross-sectional view of the press pump of the first embodiment, wherein the press pump is in a downward pressing state.

[0023] Figure 3a shows a perspective view of the pre-pressurized check valve assembly in the press pump.

[0024] Figure 3b shows an exploded perspective view of the pre-pressure check valve assembly of Figure 3a.

[0025] Figure 4a shows a cross-sectional view of the piston rod included in the pre-pressurized check valve assembly.

[0026] Figure 4b shows a cross-sectional view of the piston included in the pre-compression check valve assembly.

[0027] Figure 4c shows a cross-sectional view of the piston head included in the pre-pressurized check valve assembly.

[0028] Figure 5a shows a cross-sectional view of the pre-pressurized check valve assembly in the closed state.

[0029] Figure 5b shows a cross-sectional view of the pre-pressurized check valve assembly in the process of being opened, with the first seal open and the second seal still in a sealed state.

[0030] Figure 5c shows a cross-sectional view of the pre-pressurized check valve assembly in the fully open state.

[0031] Figure 6 shows a pre-pressurization check valve assembly for a press pump according to a second embodiment.

[0032] Figure 7 shows a cross-sectional view of the piston head and piston of the pre-pressurized check valve assembly of Figure 6, with the piston in a position that is displaced upward relative to the piston head.

[0033] Figure 8 shows an exploded view of the pre-pressurization check valve assembly for a press pump according to the third embodiment.

[0034] Figure 9 shows a cross-sectional view of the pre-pressurized check valve assembly of Figure 8 in its assembled state, with the first and second sealing parts sealed.

[0035] Figure 10 shows another cross-sectional view of the pre-pressure check valve assembly of Figure 8 in its assembled state, with the first and second seals removed.

[0036] (Symbol Explanation) 1 Press Pump 11 Press Head 12 Gear Cuff 13 Cylinder 14 Elastic Reset Mechanism 20 Piston Rod 21 Elastic Preload Component 22 Piston Rod Inner Hole 23 Piston Rod Outer Surface 24 Feed Hole 25 Support Flange 30 Piston Head 31 Liquid Guide Groove 32 Sealing Sleeve 33 Second Inclined Surface 34 Sleeve Outer Surface 35 Inner Column 36 Sleeve Inner Surface 40 Piston 41 Outer Ring 42 Inner Ring 43 First Inclined Surface 44 Piston Inner Ring Inner Surface 45 Piston Inner Ring Outer Surface Detailed Implementation

[0037] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the embodiments shown in the drawings are merely preferred embodiments of the present invention and do not constitute a limitation on the scope of the present invention. Those skilled in the art can make various obvious modifications, variations, and equivalent substitutions to the present invention based on the embodiments shown in the drawings. Furthermore, without contradiction, the technical features in the different embodiments described below can be arbitrarily combined with each other, all of which fall within the protection scope of the present invention.

[0038] <First Embodiment>

[0039] Figure 1 shows a cross-sectional view of the press pump 1 according to the first embodiment of this application, wherein the press pump 1 is in an upper standby state. Figure 2 shows another cross-sectional view of the press pump 1, wherein the press pump 1 is in a downward pressing state. The press pump 1 shown in the figures is specifically a spray pump, but the press pump 1 involved in this application may also be other types of press pumps.

[0040] The press pump 1 includes a press head 11, a toothed sleeve 12, and a cylinder 13. The toothed sleeve 12 and the cylinder 13 are connected together. A piston rod 20 is connected to the lower part of the press head 11, for example, the piston rod 20 can be connected to the inner sleeve of the press head 11. A piston head 30 is connected to the lower end of the piston rod 20, and a piston 40 is sleeved on the outer periphery of the piston head 30. The end of the piston rod 20 with the piston 40 extends into the interior of the cylinder 13, and the piston 40 is in a sealing fit with the inner surface of the cylinder 13.

[0041] When the pressure head 11 is pressed downwards, as shown in Figure 2, the piston rod 20, along with the piston head 30 and piston 40 connected thereto, move downwards relative to the cylinder 13, causing the volume in the cylinder 13 to decrease and the pressure of the product to increase. Furthermore, during this downward movement, due to the friction between the piston 40 and the inner wall of the cylinder 13, the downward movement of the piston 40 lags behind that of the piston head 30, causing the piston 40 to shift upwards relative to the piston head 30. This releases the seal between the piston 40 and the piston head 30, opening the passage to the nozzle of the pressure head 11, allowing the product in the cylinder 13 to flow to the nozzle of the pressure head 11 and ultimately be dispensed.

[0042] After the pressure applied to the pressure head 11 is released, the pressure head 11 can move upward relative to the dental sleeve 12 to return to its upper ready position as shown in FIG1. ​​For example, an elastic reset mechanism 14 can be provided between the pressure head 11 and the dental sleeve 12 or cylinder 13 to automatically move the pressure head 11 upward after the pressure is released. The elastic reset mechanism 14 is, for example, a plastic spring made of plastic. Alternatively, the pressure head 11 can also be manually pulled upward to its upper ready position by the user, which is also within the scope of this application. During the upward movement, the position of the piston 40 relative to the piston head 30 will also move downward due to the friction between the piston 40 and the inner surface of the cylinder 13, thereby forming a seal between the piston 40 and the piston head 30 to prevent product leakage.

[0043] Based on the above, it can be understood that in this application, the piston rod 20, piston head 30, and piston 40 together constitute the one-way valve assembly in the press pump 1, particularly the upper one-way valve of the press pump 1. Figure 3a shows a perspective view of the one-way valve, and Figure 3b is an exploded perspective view showing the components of the one-way valve. An elastic preload member 21 is provided at the lower end of the piston rod 20. The elastic preload member 21 is made of plastic and can be integrally formed at the lower end of the piston rod 20 as shown, or it can be formed separately and then installed on the piston rod 20.

[0044] The elastic preload member 21 may include multiple elastic strips, such as four elastic strips arranged at equal intervals along the circumference of the piston rod 20 as shown in the figure, which may be generally "J" shaped. The free ends of the elastic strips may abut against the piston 40 to apply preload to the piston 40. In an exemplary configuration, the free ends of the elastic strips of the elastic preload member 21 abut against the connecting web between the inner and outer rings of the piston 40.

[0045] The elastic preload 21 may also include other numbers of elastic strips, such as two, three, five, etc. The elastic strips may also take other shapes, such as bow shape, S shape, etc., or the elastic preload 21 may take other structures besides elastic strips, all of which are within the scope of this application.

[0046] Figures 4a to 4c show cross-sectional views of piston rod 20, piston head 30, and piston 40, respectively, from which the decoupling of each component can be seen more clearly.

[0047] As shown in Figure 4a, an elastic preload member 21 is provided at the lower end of the piston rod 20. The elastic preload member 21 may include, for example, at least one, preferably multiple elastic strips. A piston rod inner hole 22 is formed inside the piston rod 20, and the piston rod inner hole 22 preferably extends longitudinally through the piston rod 20.

[0048] The piston 40 includes an outer ring 41 and an inner ring 42, which are connected by a web. The outer ring 41 of the piston 40 can seal against the inner surface of the cylinder 13. A first inclined surface 43 is formed at the lower end of the inner ring 42 of the piston 40, and an inner surface 44 of the piston inner ring is located above the first inclined surface 43 on the lower surface of the inner ring 42. The inner surface 44 of the piston inner ring extends approximately along the longitudinal direction of the piston 40 and has a height H1 (shown in Figure 5a). The first inclined surface 43 of the inner ring 42 and the inner surface 44 of the piston inner ring can seal against and disengage with corresponding structures on the piston head 30, thereby realizing the closing and opening of the one-way valve, as will be described in more detail below.

[0049] As shown in Figure 4c, the piston head 30 includes a body and a sealing sleeve 32 formed below the body. At least one liquid guide groove 31 is formed on the body of the piston head 30. This groove 31 engages with the inner wall of the piston rod bore 22 of the piston rod 20 to form a liquid channel for the product to pass through. Liquid or semi-liquid products can enter the channel in the pressure head 11 through this liquid channel and reach the nozzle of the pressure head 11.

[0050] A second inclined surface 33 is formed at or near the lower end of the sealing sleeve 32. This second inclined surface 33 can cooperate with the first inclined surface 43 of the inner ring 42 of the piston 40 to form a first sealing portion. Above the second inclined surface 33 is the outer sleeve surface 34 of the sealing sleeve 32. This outer sleeve surface 34 cooperates with the inner surface 44 of the inner ring 42 of the piston 40 to form a second sealing portion.

[0051] Next, refer to Figures 5a-5c, which show how the check valve assembly operates.

[0052] In the state shown in Figure 5a, the one-way valve assembly is in the closed state, which corresponds to the upper standby state of the press pump 1. In the state shown in Figure 5a, the first inclined surface 43 of the inner ring 42 of the piston 40 and the second inclined surface 33 of the sealing sleeve 32 of the piston head 30 cooperate to form a first sealing part, and the inner side surface 44 of the inner ring 42 of the piston 40 cooperates with the outer side surface 34 of the sealing sleeve 32 to form a second sealing part. At this time, the elastic preload member 21 is in the relaxed state.

[0053] Next, when the pressure head 11 is pressed down, the pressure head 11 moves downward along with the piston rod 20 and the piston head 30. Friction exists between the piston 40 and the inner surface of the cylinder 13, causing the piston 40 to move upward relative to the piston head 30. The first inclined surface 43 of the piston 40 disengages from the second inclined surface 33 of the piston head 30, thereby releasing the first seal, as shown in Figure 5b. At this time, the outer side 34 of the sleeve remains in contact with the inner side 44 of the piston inner ring, thus maintaining the second seal. During this process, the elastic preload member 21 moves from a relaxed state to a loaded state, and because the second seal remains sealed, products that are not fully pressurized will not flow out.

[0054] Next, as shown in Figure 5c, as the piston 40 continues to move upward relative to the piston head 30, when the upward displacement of the piston 40 relative to the piston head 30 reaches or exceeds the height H1 of the inner side surface 44 of the piston inner ring, the inner side surface 44 of the piston inner ring disengages from the contact with the outer side surface 34 of the sleeve, thereby releasing the second seal. At this time, the one-way valve assembly is fully open, allowing liquid or semi-liquid product to flow through. During the upward displacement of the piston 40 relative to the piston head 30 to a distance equal to the height H1, the elastic preload member 21 is gradually loaded, and the pressure of the product in the cylinder 13 gradually accumulates. When both the first and second seals are released, the product pressure reaches the required pressure and can flow through the one-way valve assembly.

[0055] When pumping ends, piston 40 moves downward relative to piston head 30, and the inner side 44 of the piston inner ring first contacts the outer side 34 of the sleeve, thus achieving a seal at the second sealing part. At this time, the volume of space in cylinder 13 increases and the pressure decreases, thereby creating a negative pressure. This negative pressure can draw back the droplets in the nozzle of pressure head 11, thereby preventing the problem of large droplets leaking out at the end of pumping.

[0056] Therefore, in the aforementioned one-way valve assembly, in the standby state (Fig. 5a), the elastic preload member 21 can be in a relaxed state. During the pressing process, the elastic preload member 21 is gradually loaded during the initial pressing. During this process, the one-way valve assembly is not fully open, thus allowing the product in the cylinder 13 to be gradually pressurized. When the one-way valve assembly is fully open, the product also reaches the required pressure. Thus, in the standby state, the elastic preload member 21 can be in a fully relaxed or relatively relaxed state. The elastic preload member 21 is only loaded during the pressing process, thus preventing or at least mitigating the problem of creep caused by long-term pressure on the elastic preload member 21, while still ensuring that the pumped product has the predetermined pressure. In addition, when pumping ends, the second sealing part first achieves a seal, forming a negative pressure, thereby drawing back the product droplets remaining in the nozzle of the pressure head 11 to avoid the problem of large droplets falling.

[0057] Preferably, as shown in the figure, an inner column 35 is also provided on the inner side of the sealing sleeve 32. By providing the inner column 35, the dead volume in the cylinder 13 can be reduced, and the number of times the product is pumped can be reduced.

[0058] <Second Embodiment>

[0059] Figures 6 and 7 illustrate the application of a one-way valve assembly in a push-pump 1 according to the second embodiment of this application. Unless otherwise stated or obviously contradicted, the technical features described above in the first embodiment are also applicable to the second embodiment, and vice versa. Here, technical features identical to those in the first embodiment will not be described in detail, but only technical features not mentioned in the first embodiment will be disclosed in detail.

[0060] In the one-way valve assembly of the second embodiment, a sealing sleeve 32 is provided at the lower end of the piston head 30. The sealing sleeve 32 extends upward, forming a gap between the sealing sleeve 32 and the body of the piston head 30, in which the inner ring 42 of the piston 40 can be received. A second inclined surface 33 is formed at the bottom of the gap, which can cooperate with the first inclined surface 43 of the inner ring 42 to form a first sealing portion. The inner ring 42 also includes an outer surface 45 of the piston inner ring with a certain height, which can cooperate with the inner surface 36 of the sleeve of the sealing sleeve 32 to form a second sealing portion.

[0061] Similar to the first embodiment, during the pressing process, the piston 40 moves upward relative to the piston head 30, the first inclined surface 43 separates from the second inclined surface 33, and the first sealing part is released first. As the piston 40 continues to move upward a certain distance, the outer side 45 of the piston inner ring disengages from the inner side 36 of the sleeve, thereby releasing the seal of the second sealing part.

[0062] <Third Embodiment>

[0063] Figures 8-10 illustrate the application of the one-way valve assembly of the third embodiment of this application in the push pump 1. Unless otherwise stated or obviously contradicted, the technical features described above in the first and second embodiments are equally applicable to the third embodiment, and vice versa. Here, technical features identical to those in the first and second embodiments will not be described in detail, but only technical features not mentioned in the first and second embodiments will be disclosed in detail.

[0064] Figure 8 shows an exploded view of the one-way valve assembly. Similar to the first and second embodiments, a first inclined surface 43 is formed on the lower outer surface of the inner ring 42 of the piston 40. In the third embodiment, the upper part of the piston head 30 is provided with an upwardly extending sealing sleeve 32, and a second inclined surface 33 is formed on the inner side of the sealing sleeve 32. The first inclined surface 43 can mate with the second inclined surface 33 to form a first sealing portion, as shown in Figure 9.

[0065] In addition, the inner side 44 of the inner ring of the piston 40 has a certain height and can cooperate with the outer side 23 of the piston rod of the piston rod 20 to form a second sealing part, as shown in Figure 9.

[0066] An elastic preload member 21 is provided at the upper end of the piston 40, and the upper end of the elastic preload member 21 is a free end. A radially extending support flange 25 is formed on the outer peripheral surface of the piston rod 20, and the free end of the elastic preload member 21 is supported on the support flange 25.

[0067] Regarding the structure of the one-way valve assembly in the third embodiment, during the pressing process, the piston 40 moves upward relative to the piston head 30 and the piston rod 20. First, the first inclined surface 43 and the second inclined surface 33 disengage from each other, thereby releasing the first sealing part. As the piston 40 continues to move upward, until the feed hole 24 on the piston rod 20 leading to the inner hole 22 of the piston rod is exposed, at which point the second sealing part is released.

[0068] The structure of specific embodiments of this application has been described in detail above. Those skilled in the art will recognize that various obvious modifications, variations, and combinations can be made based on the disclosed structure, and these are all within the scope of this application.

[0069] For example, the piston head 30 and the piston rod 20 can be connected in various ways, such as the snap ring-slot structure shown in the figure, or a threaded connection structure, or the piston head 30 can be integrally formed with the piston rod 20.

[0070] The elastic preload element 21 can be integrally formed on the piston rod 20, or it can be manufactured separately and then installed on the piston rod 20. The elastic preload element 21 can include any number and shape of elastic strips, and multiple elastic strips can be spaced equally apart, or the spacing can vary.

[0071] In the embodiments disclosed above, the first sealing portion and the second sealing portion are formed between the piston 40 and the piston head 30, or one is formed between the piston 40 and the piston head 30, and the other is formed between the piston 40 and the piston rod 20. Alternatively, both the first sealing portion and the second sealing portion may be formed between the piston 40 and the piston rod 20, which is also within the scope of this application.

[0072] In the structures disclosed above, in the first and second embodiments, the elastic preload member 21 is formed or connected to the piston rod 20, or as in the third embodiment, the elastic preload member 21 is formed on the piston 40, and a support flange for the elastic preload member 21 to abut against is provided on the piston rod 20. Alternatively, the elastic preload member 21 may also be formed on the piston head 30. Or, in the case where the elastic preload member 21 is formed on the piston 40, a support portion cooperating with the elastic preload member 21 may also be provided on the piston head 30. These variations are also within the scope of this application.

Claims

1. A pre-compression check valve assembly, wherein the pre-compression check valve assembly is disposed in an all-plastic push-pump, the pre-compression check valve assembly comprising a piston rod, a piston head, and a piston of the all-plastic push-pump, the piston head being fixedly connected to the piston rod, the piston being sleeved on the piston head, and the pre-compression check valve assembly further comprising an elastic pre-compression element, characterized in that, The elastic preload member is disposed on one of the piston, the piston head, and the piston rod, and the elastic preload member is configured such that when the preload check valve assembly is in the closed state, the elastic preload member is in the relaxed state, and when the piston moves upward relative to the piston head, the elastic preload member is gradually loaded until the distance the piston moves upward relative to the piston head reaches or exceeds a predetermined distance, at which point the preload check valve opens.

2. The pre-pressure check valve as described in claim 1, characterized in that, A first sealing portion is formed between the piston and the piston rod or the piston head, and a second sealing portion is also formed between the piston and the piston rod or the piston head. The second sealing portion has a height along the axial direction of the all-plastic press pump. The first sealing portion and the second sealing portion are configured such that when the piston moves upward relative to the piston head, the first sealing portion opens first, and the second sealing portion opens after the distance by which the piston moves upward relative to the piston head reaches or exceeds the height of the second sealing portion.

3. The pre-pressure check valve assembly as described in claim 1, characterized in that, The piston has an outer ring and an inner ring. The lower end of the inner ring has a first inclined surface. The piston head includes a sealing sleeve. The lower end of the sealing sleeve has a second inclined surface. The first inclined surface can cooperate with the second inclined surface to form the first sealing part.

4. The pre-pressure check valve assembly as described in claim 3, characterized in that, The sealing sleeve extends downward, and the outer side of the sealing sleeve can cooperate with the inner side of the piston inner ring to form the second sealing part.

5. The pre-pressure check valve assembly as described in claim 3, characterized in that, The sealing sleeve extends upward, forming a gap between the sealing sleeve and the body of the piston head, the gap accommodating the inner ring, and the second inclined surface forming at the bottom of the gap; and The inner side of the piston head sleeve can mate with the outer side of the inner piston ring to form the second sealing part.

6. The pre-pressure check valve assembly as described in claim 2, characterized in that, The piston has an outer ring and an inner ring. A first inclined surface is formed at the lower end of the inner ring. The piston head includes a sealing sleeve. A second inclined surface is formed on the inner side of the sealing sleeve. The first inclined surface can mate with the second inclined surface to form the first sealing portion; and / or The inner side of the inner piston ring can mate with the outer side of the piston rod to form the second sealing part.

7. The pre-pressure check valve assembly as described in claim 3, characterized in that, An inner column is formed inside the sealing sleeve.

8. The pre-pressure check valve assembly as described in any one of claims 1 to 7, characterized in that, The elastic preload component includes multiple elastic strips.

9. The pre-pressure check valve assembly as described in claim 8, characterized in that, The elastic strip is formed in a "J" shape, and / or the elastic strip is arranged at equal intervals along the circumference.

10. The pre-pressure check valve assembly as described in any one of claims 1 to 7, characterized in that, At least one liquid guiding groove is formed on the body of the piston rod, the liquid guiding groove extends along the axial direction of the piston rod, and the liquid guiding groove cooperates with the inner hole of the piston rod to form a channel for the product to flow through.

11. The pre-pressure check valve assembly as described in any one of claims 1 to 7, characterized in that, The piston rod is integrally formed with the piston head.

12. A fully plastic push-button pump, the fully plastic push-button pump comprising a pressure head, a toothed sleeve, and a cylinder, wherein the toothed sleeve and the cylinder are fixedly connected together, characterized in that, The all-plastic press pump includes a pre-pressurized one-way valve assembly as described in any one of claims 1 to 11, wherein the piston rod is connected to the lower part of the press head, the piston is located inside the cylinder, and is sealed to the inner surface of the cylinder.

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