Liquid pump with elastic piston and method for manufacturing the same

Abstract

A liquid pump includes a pressure head, a toothed sleeve and a cylinder. A piston rod is connected to the bottom of the pressure head, an elastic piston is arranged on the piston rod, and the toothed sleeve and the cylinder are connected together. The piston includes: a lower ring located at the bottom of the piston, which has a first outer diameter; and a joint part, which has a second outer diameter smaller than the first outer diameter, so that the joint part is recessed inward relative to the lower ring to form a thin-walled part, and the joint part cooperates with at least one through hole of the piston rod to form an upper one-way valve of the liquid pump. A method for manufacturing the liquid pump is also disclosed. The liquid pump with the above structure allows the upper one-way valve to be easily opened, and the piston can also be easily arranged on the piston rod.

Description

Technical Field

[0001] The present invention relates to a liquid pump for pumping a product from a container, and in particular to a liquid pump with an elastic piston. Background Art

[0002] A liquid pump is often installed on the packaging container of daily chemical products such as shampoo, shower gel or similar products to pump the product out of the container for use by consumers. Here, the so-called "liquid pump" includes a pump mechanism that can pump any fluid or semi-fluid product, including liquids, emulsions, suspensions, etc.

[0003] Fig.14a and 14b An exemplary prior art liquid pump 1 is shown, wherein Fig.14a The liquid pump 1 shown in FIG. is in the upper position, and Fig.14a The liquid pump 1 shown in the figure is in a downward pressure state. As shown in the figure, the liquid pump 1 generally includes a pressure head 10, a socket 20, a cylinder 30 and a piston rod 40. The socket 20 is connected to the cylinder 30, and the piston rod 40 is connected below the pressure head 10 and extends into the cylinder 30. A piston 50 is provided at the lower end of the piston rod 40. More specifically, the piston 50 is sleeved on the recessed portion at the lower end of the piston rod 40. A through hole is formed at the portion of the piston rod 40 where the piston 50 is provided, which is connected to the cavity inside the piston rod 40, and the through hole cooperates with the piston 50 to constitute the upper one-way valve 51 of the liquid pump 1. Fig.14a In the upper position shown in FIG. 1 , the piston 50 covers the through hole on the piston rod 40, so that the upper check valve 51 is in the closed position. Fig.14b As shown, when the pressure head 10 is pressed downward, the piston rod 40 moves downward accordingly. During this process, due to the friction between the piston 50 and the inner wall of the cylinder 30, the piston 50 is deformed, opening the through hole on the piston rod 40, so that the upper one-way valve 51 is opened.

[0004] In practice, it is found that the liquid pump of the above structure has some problems. For example, in the liquid pump, the middle part of the piston is clamped in the recessed part of the piston rod. When the pressure head is pressed downward, the middle part of the piston is not easy to deform, resulting in the upper one-way valve not being easy to open, or requiring consumers to apply a large pressing force to open the upper one-way valve, thus affecting the consumer's use experience. Moreover, the difficulty or delay in opening the upper one-way valve may potentially lead to risks such as suffocation of the liquid pump and backflow of the lower one-way valve.

[0005] In addition, it can be seen from the figure that in order to ensure that the position of the piston on the piston rod can be limited within a certain range, the piston is fitted in the recessed portion of the piston rod, which also poses a challenge to the installation of the piston. In the process of installing the existing liquid pump of this type, the piston needs to be forcibly expanded so that the piston can be put on the larger diameter part above or below the recessed portion of the piston rod, and then slide towards the recessed portion to enter the recessed portion. This kind of assembly is time-consuming and laborious for the assembler, and during the installation process, since the piston is forcibly expanded, there is a risk of damage to the piston during the installation process, which in turn affects the normal realization of the function of the liquid pump.

[0006] Therefore, there is still a need in the art for a liquid pump with an improved structure to overcome at least one of the above-mentioned technical problems. Summary of the invention

[0007] The present invention is made to solve at least one of the problems existing in the above prior art. The purpose of the present invention is to provide a liquid pump with an improved structure, which can easily open the one-way valve on the liquid pump during the pressing process. In addition, the liquid pump of the present invention can also be easily installed.

[0008] The liquid pump of the present invention includes a pressure head, a socket and a cylinder, a piston rod is connected below the pressure head, the socket and the cylinder are connected together, and the lower end of the piston rod extends to the inside of the cylinder, a recessed portion is formed on the piston rod, and at least one through hole extending from the outer surface of the piston rod to the internal cavity of the piston rod is formed in the recessed portion, wherein an elastic piston is sleeved on the recessed portion of the piston rod, and the piston includes: a lower ring located at the lower part of the piston, the lower ring has a first outer diameter; and a coupling portion, the coupling portion has a second outer diameter smaller than the first outer diameter, so that the coupling portion is recessed inwardly relative to the lower ring to form a thin-walled portion, and the coupling portion cooperates with at least one through hole of the piston rod to form an upper one-way valve of the liquid pump.

[0009] For the liquid pump of the above structure, the joint between the piston and the piston rod is in the form of a thin-walled portion, which is easier to deform than the existing piston, thereby facilitating easy opening of the one-way valve thereon. Moreover, the piston with a thin-walled portion is easier to install on the piston rod and is not easily damaged during installation.

[0010] Furthermore, the piston also has an upper ring located at the upper part of the piston, and the joint is located at the upper ring and the lower ring, wherein the upper ring has a third outer diameter, which is smaller than the first outer diameter and larger than the second outer diameter. The upper ring can make the connection between the piston and the piston rod more stable.

[0011] Preferably, a convex ring is formed on the inner surface of the upper ring, and a groove is formed on the piston rod. When the piston is installed on the piston rod, the convex ring is embedded in the groove. The convex ring-groove structure can help the sealing cooperation between the upper part of the piston and the piston rod.

[0012] Preferably, a step portion is formed on the piston rod, the step portion is located above the piston, and when the ram is at the upper dead point of its stroke, the step portion contacts the toothed sleeve, thereby preventing the ram from continuing to move upward beyond the upper dead point of its stroke.

[0013] Preferably, the lower ring of the piston includes a sealing surface, and when the ram moves to the upper dead center of its stroke, the sealing surface contacts the portion of the socket extending into the cylinder. The sealing surface helps prevent leakage of the product.

[0014] In another structure, the liquid pump also includes a cylinder head, which is mounted on the sleeve, and the lower ring of the piston includes a sealing surface. When the pressure head moves to the upper dead center of its stroke, the sealing surface contacts the part of the cylinder head extending into the cylinder.

[0015] Preferably, a demoulding aid is also formed on the piston, which helps the piston to be stripped from the piston rod after the piston is formed. For example, the demoulding aid can be a groove or a protrusion formed on the upper surface of the lower ring of the piston.

[0016] In an alternative structure, the liquid pump further comprises a piston head, and the piston rod, the piston and the piston head are assembled together to form a piston assembly.

[0017] Preferably, the inner wall of the cylinder is formed with: an upper protrusion, which contacts the piston when the pressure head is at the upper dead point of its stroke; and / or a lower protrusion, which contacts the piston when the pressure head is at the lower dead point of its stroke. The upper protrusion and the lower protrusion can increase the friction between the piston and the inner wall of the cylinder, thereby further facilitating the deformation of the piston and improving the sensitivity of the upper check valve.

[0018] It also relates to a method for manufacturing the above liquid pump, wherein the piston rod and the piston are formed by the following steps:

[0019] Molding a piston rod in a piston rod mold, the piston rod mold comprising a core mold and an outer mold;

[0020] After the piston rod is manufactured, the outer mold is removed, and the mold core is retained in the manufactured piston rod;

[0021] A piston mold is put on the position of the concave part of the piston rod to mold the piston, wherein the piston mold comprises an insert extending radially inward, and the shape of the insert corresponds to the shape of the joint part of the piston;

[0022] After the piston is manufactured, the cores of the piston mold and the piston rod mold are removed from the piston rod and the piston.

[0023] It can be seen that this method adopts a secondary molding process, so that the piston can be easily formed on the piston rod, avoiding the forced expansion of the piston diameter when the piston is mounted on the piston rod, and can also easily form a thin-walled portion on the piston.

[0024] The piston rod is made of a first molding material, and the piston is made of a second molding material. Preferably, the molding temperature of the first molding material is higher than that of the second molding material; and / or, the first molding material and the second molding material are difficult to adhere together. In this way, it is convenient to peel the piston from the piston rod after molding is completed to prevent them from sticking together.

[0025] Further preferably, in order to prevent the piston rod and the piston from sticking together, the mold for molding the piston rod can be polished, especially the position on the mold corresponding to the part of the piston rod that will contact the piston. In this way, the surface of the manufactured piston rod, especially the surface of the part that contacts the piston, can be made smoother, thereby facilitating the separation of the piston and the piston rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings show non-limiting preferred implementation structures of the present invention, and the features and advantages of the present invention can be more clearly seen in conjunction with the accompanying drawings.

[0027] Figure 1a A sectional view of a liquid pump according to a first embodiment of the present invention is shown, wherein the liquid pump is at the top dead center of its stroke.

[0028] Figure 1b Another cross-sectional view of the liquid pump according to the first embodiment of the present invention is shown, wherein the liquid pump is in a depressed state.

[0029] Figure 2a Shows Figure 1a and 1b A cross-sectional view of an assembly of a piston rod and a piston of a liquid pump, wherein the piston is in an undeformed state.

[0030] Figure 2b yes Figure 2a Another cross-sectional view of the piston rod and piston assembly is shown, wherein the piston is deformed so that the upper non-return valve is opened.

[0031] Figure 2c yes Figure 2b A partial enlarged view of part I in FIG.

[0032] Figure 3a is a front view of the piston rod of the first embodiment.

[0033] Figure 3b yes Figure 3a A cross-sectional view of the piston rod is shown.

[0034] Figure 3c yes Figure 3a A perspective view of the piston rod is shown.

[0035] Figure 4a is a cross-sectional view of the piston of the first embodiment.

[0036] Figure 4b yes Figure 4a A perspective view of the piston is shown.

[0037] Figure 5 The present invention is a cutaway stereogram of a piston with a modified structure.

[0038] Figure 6a A sectional view showing a liquid pump according to a second embodiment of the present invention, showing a state in which the pressure head is initially pressed down.

[0039] Figure 6b Another cross-sectional view of the liquid pump according to the second embodiment is shown, wherein the state in which the pressure head is initially reset is shown.

[0040] Figure 7 A cross-sectional view showing a piston assembly of a liquid pump according to a second embodiment.

[0041] Figure 8 Shows Figure 7 A cross-sectional view of the piston rod of the piston assembly is shown.

[0042] Fig. 9 Shows Figure 7 A cross-sectional view of a piston of a piston assembly is shown.

[0043] Fig.10 Shows Figure 7 A cross-sectional view of the piston head of the piston assembly is shown.

[0044] Fig.11 A sectional view showing a cylinder of a liquid pump according to a second embodiment.

[0045] Fig.12 A cross-sectional view of a piston assembly showing a modified structure.

[0046] Fig.13 A cross-sectional view of a piston assembly showing another modified structure.

[0047] Fig.14a A cross-sectional view of a conventional liquid pump is shown, wherein the liquid pump is in an upper standby state.

[0048] Fig.14b Shows Fig.14aAnother cross-sectional view of a liquid pump, wherein the liquid pump is in a pressed down state. DETAILED DESCRIPTION

[0049] In order to facilitate the understanding of the present invention, the specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that the drawings show only preferred embodiments of the present invention, which should not be construed as limiting 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, and the technical features of the different embodiments described below can be arbitrarily combined with each other without contradiction, and these all fall within the scope of the present invention.

[0050] In the following specific description of the present invention, the terms such as "upper" and "lower" used to indicate direction and orientation are based on the orientation of the liquid pump shown in the figure. It should be understood that the orientation of the liquid pump may change according to the specific application.

[0051] <First Embodiment>

[0052] Figure 1a 5 shows a liquid pump 100 according to a first embodiment of the present invention. Figure 1a and 1b As shown, the liquid pump 100 generally includes a pressure head 110, a toothed sleeve 120, a cylinder 130 and a piston rod 140. The toothed sleeve 120 and the cylinder 130 are connected together, one end of the piston rod 140 is connected to the lower part of the pressure head 110, and the other end extends into the cylinder 130. A piston 150 is provided on the end of the piston rod 140 extending into the cylinder 130. The piston 150 is a deformable elastic piston. Figure 1b As shown, during the process of pressing the pressure head 110 downward, the friction between the piston 150 and the inner wall of the cylinder 130 causes the piston 150 to deform, thereby exposing the through hole provided on the piston rod 140. It can be seen that the through hole on the piston 150 and the piston rod 140 cooperate to form the upper one-way valve 160 of the liquid pump 100.

[0053] Figure 2a and Figure 2b 1 shows a cross-sectional view of the piston rod 140 and the piston 150 assembled together, Figure 2c It shows that Figure 2b It can be seen that the middle portion of the piston 150 in the liquid pump 100 along the longitudinal direction is hollowed out along the radial direction to form a thin-walled portion 153. When the piston rod 140 moves downward with the pressure head 110, the thin-walled portion 153 is easily deformed, thereby exposing the through hole ( Figure 2b), thereby allowing the product to enter the inner cavity of the piston rod 140 through the through hole as shown by the arrow A in the figure, and then can be distributed to the outside of the container through the pressure head 110.

[0054] Figure 3a-3c 1 shows the specific structure of the piston rod 140. The piston rod 140 includes a recessed portion 141 disposed near the lower end, and at least one through hole 142 is formed at the recessed portion 141. The through hole 142 extends from the outer surface of the piston rod 140 to the cavity inside the piston rod 140, thereby forming a channel for the product to enter. In a preferred implementation structure, two or more through holes 142 may be included, and these through holes 142 are arranged at intervals from each other around the circumference of the piston rod 140, and preferably, the through holes 142 are arranged at equal intervals.

[0055] Preferably, a step portion 143 is also formed on the piston rod 140, and the step portion 143 is located, for example, above the piston 150. When the ram 110 and the piston rod 140 are at the upper dead point of their stroke, the step portion 143 can contact the braces 120 to prevent the ram 110 and the piston rod 140 from continuing to move upward.

[0056] Figure 4a and 4b The cross-sectional view and the stereoscopic view of the piston 150 disposed on the piston rod 140 are respectively shown. The piston 150 has a lower ring 151 located at the bottom, an upper ring 152 located at the top, and a joint portion located therebetween, and the joint portion is matched with the recessed portion 141 on the piston rod 140. The lower ring 151 of the piston 150 has a larger first outer diameter, the joint portion has a second outer diameter, the second outer diameter is smaller than the first outer diameter of the lower ring 151, and the upper ring 152 has a third outer diameter, the third outer diameter is smaller than the first outer diameter and larger than the second outer diameter. In the present invention, the joint portion is a thin-walled portion 153 formed by radially inwardly hollowing out, or the thin-walled portion 153 is a radially inwardly concave structure. Compared with the elastic piston in the prior art, the thin-walled portion 153 is easier to deform.

[0057] The lower ring 151 of the piston 150 further includes a sealing surface 155, which is formed at the upper portion of the lower ring 151. When the ram 110 and the piston rod 140 move upward to the upper dead center of their travel, the sealing surface 155 may contact the portion of the toothed sleeve 120 extending into the cylinder 130, such as Figure 1a Thus, at top dead center, a seal is formed between the piston 150 and the toothed sleeve 120 to help prevent the product below the piston 150 in the cylinder 130 from leaking out from the contact position between the piston 150 and the cylinder 130 .

[0058] A preferred method of forming the piston rod 140 and the piston 150 in the liquid pump 100 of the present invention will be described below.

[0059] First, the piston rod 140 is injection molded in a mold. The mold for injection molding of the piston rod 140 includes a core mold and an outer mold, and a molding material is injected into a mold cavity between the core mold and the outer mold, and the molding material is solidified to form a blank of the piston rod 140. After the injection molding of the piston rod 140 is completed, the outer mold is removed, while the core mold is retained in the obtained piston rod 140.

[0060] Next, a mold for forming the piston 150 is put on the position of the recessed portion 141 of the molded piston rod 140. The mold for forming the piston 150 has a radially inwardly extending insert, and the shape of the insert corresponds to the concave shape of the thin-walled portion 153 of the piston 150. The molding material for forming the piston 150 is injected into the mold. Here, preferably, the molding material for forming the piston 150 is different from the molding material for forming the piston rod 140, and in particular, their molding temperatures are greatly different. Specifically, the molding material for forming the piston rod 140 has a higher molding temperature, while the molding temperature of the molding material for forming the piston 150 is lower. More preferably, the material for forming the piston 150 and the material for forming the piston rod 140 have poor adhesion properties to each other. In this way, it is convenient to peel the piston 150 and the piston rod 140 apart from each other after the piston 150 is molded.

[0061] Figure 5 A further preferred three-dimensional cutaway view of the piston 150 is also shown. It is shown that a groove 154 is formed on a portion of the thin-walled portion 153 of the piston 150, such as the groove 154 formed in the upper surface of the lower ring 151 shown in the figure. The groove 154 may include a plurality of discrete grooves distributed around the circumference, or an annular groove formed by continuously extending along the circumference. Alternatively, in other embodiments, a protrusion may be used to replace the groove 154 shown in the figure.

[0062] By means of the structure such as the groove 154 , when the piston 150 is demolded after being molded, the friction between the piston 150 and the mold can be increased, thereby facilitating the peeling of the piston 150 from the piston rod 140 while demolding.

[0063] Further preferably, in order to facilitate the peeling of the piston 150 from the piston rod 140 during demolding, the mold used to mold the piston rod 140 can be polished. For example, the portion of the mold corresponding to the portion of the piston rod 140 that will contact the piston 150, such as the mold portion corresponding to the outer surface of the recessed portion 141 of the piston rod 140, can be polished. This can improve the smoothness of the molded piston rod 140 in this portion, thereby facilitating the peeling of the piston 150 from the piston rod 140.

[0064] It can be seen that in the present invention, the piston 150 is formed on the piston rod 140 through a secondary injection molding process. In this way, the piston 150 can be installed on the piston rod 140 without forcibly expanding the diameter as in the prior art, and this method can also easily form a thin-walled portion 153 on the piston 150.

[0065] In addition, in the illustrated embodiment, the mouthpiece 120 is an integrated mouthpiece. In addition, a cylinder head may be included, which is installed together with the mouthpiece, and the part of the cylinder head that extends into the cylinder 130 is the part of the cylinder head. Furthermore, the sealing surface 155 mentioned above may contact the part of the cylinder head that extends into the cylinder 130.

[0066] <Second Embodiment>

[0067] Figures 6a to 11 A liquid pump 200 of a second embodiment of the present invention is shown. In the following description of the second embodiment, the technical features of the second embodiment that are different from the first embodiment will be mainly described. Unless there is a contrary description in the following content or there is a conflict with other technical features, the features described in the first embodiment are also applicable to the second embodiment and will not be described in detail here.

[0068] In the second embodiment, if Figure 6a and 6b As shown in , the liquid pump 200 generally includes a pressure head 210, a toothed sleeve 220, a cylinder 230 and a piston assembly 240. The toothed sleeve 220 is connected to the cylinder 230. One end (upper end) of the piston assembly 240 is connected to the lower part of the pressure head 210, and the other end (lower end) extends into the cylinder 230.

[0069] Figure 7 2 shows a cross-sectional view of a piston assembly 240. The piston assembly 240 includes a piston rod 241, a piston 242 and a piston head 244. The piston rod 241 and the piston head 244 are connected together, and a recessed portion is formed after the connection, and the recessed portion is similar to the recessed portion 141 in the first embodiment.

[0070] A through hole 245 is formed on the piston rod 241 or the piston head 244, and the position of the through hole 245 is set so that when the piston rod 241 and the piston 242 are connected together, the through hole 245 is exposed to the outside. Figure 7 As shown in FIG. 2 , the through hole 245 is formed on the piston head 244 and is located on a portion of the piston head 244 that does not overlap with the piston rod 241 in the installed state.

[0071] Of course, in another variation, the through hole 245 may also be formed on the piston rod 241 and located on a portion of the piston rod 241 that does not overlap with the piston head 244 in the installed state.

[0072] Alternatively, through holes may be formed on the piston rod 241 and the piston head 244, respectively, and when the piston rod 241 and the piston head 244 are connected to each other, the through holes of the piston rod 241 and the piston head 244 are aligned with each other to form a through hole 245 of the assembled piston assembly 240. The through hole 245 cooperates with the joint of the piston 242 to form an upper one-way valve of the liquid pump 200.

[0073] The piston assembly 240 also includes a piston 242, which has basically the same structure as the piston 150 in the first embodiment. For example, it also includes a thin-walled portion 243 formed roughly in the longitudinal middle part of the piston 242. The thin-walled portion 243 is also formed by radially hollowing out inward, and in the installed state, the thin-walled portion 243 cooperates with the recessed portion formed after the piston rod 241 and the piston head 244 are connected, thereby serving as a coupling portion of the piston 242.

[0074] In the structure of the second embodiment, the piston rod 241, the piston 242 and the piston head 244 can be molded separately and then assembled together to form the piston assembly 240. In addition, in the process of assembling the piston assembly 240 of the second embodiment, the piston 242 can be sleeved on one of the piston rod 241 and the piston head 244, and then connected to the other of the piston rod 241 and the piston 242, and the piston 242 does not need to be forcibly expanded in diameter during this process.

[0075] Of course, the piston assembly 240 may also be manufactured using the two-shot injection molding process disclosed in the first embodiment. For example, the piston rod 241 may be molded first, the piston 242 may be molded on the piston rod 241, and then the prefabricated piston head 244 may be connected to the piston rod 241. Alternatively, the piston 242 may be molded on the molded piston head 244, and then the piston head 244 and the piston 242 may be connected to the prefabricated piston rod 241.

[0076] In addition, if Fig.11 As shown, in a preferred variation of the second embodiment, an upper protrusion 231 and a lower protrusion 232 are further formed on the inner wall of the cylinder 130. The upper protrusion 231 and the lower protrusion 232 can each be in the form of a continuous convex ring, or can be in the form of a discontinuous protrusion distributed along the circumference of the cylinder 230.

[0077] Preferably, the upper protrusion 231 and the lower protrusion 232 are arranged so that when the ram 210 is at the upper dead point of its stroke, the upper protrusion 231 contacts the piston 242, especially the lower ring of the piston 242 with a larger diameter, and when the ram 210 is at the lower dead point of its stroke, the lower protrusion 232 contacts the piston 242, especially the lower ring of the piston 242 with a larger diameter.

[0078] In this way, when the pressure head 210 begins to be pressed, the upper protrusion 231 contacts the piston 242, increasing the friction between the piston 242 and the inner wall of the cylinder 230, so that the piston 242 can deform faster and open the upper check valve. When the pressure applied to the pressure head 210 is removed and the pressure head 210 is reset, the lower protrusion 232 contacts the piston 242, increasing the friction between the piston 242 and the inner wall of the cylinder 230, so that the piston 242 can deform faster and close the upper check valve. In other words, by setting the upper protrusion 231 and the lower protrusion 232, the upper check valve can respond faster and open or close.

[0079] Those skilled in the art will know that Fig.11 The structures of the upper protrusion 231 and the lower protrusion 232 shown in FIG. 2 are also applicable to the liquid pump 100 of the first embodiment.

[0080] <Other variant structures>

[0081] Fig.12 and 13 Other possible variations of the piston assembly in the liquid pump of the present invention are shown.

[0082] like Fig.12 As shown, in the first variant, the piston 350 mounted on the piston rod 340 includes a lower ring 351 with a larger diameter and a joint portion 352 with a smaller diameter. The joint portion 352 matches the recessed portion of the piston rod 340 and is a thin-walled portion that is radially recessed inward relative to the lower ring 351. In addition, the lower ring 351 of the piston 350 is generally in the form of a cone. When the pressure head of the liquid pump is pressed, the lower ring 351 of the piston 350 will be more easily deformed upward, so that the upper one-way valve can be opened more quickly.

[0083] like Fig.13As shown, in the second variant, the piston 450 mounted on the piston rod 440 includes a lower ring 451, an upper ring 452 and a joint 453 between the lower ring 451 and the upper ring 452. The joint 453 is similar to the first and second embodiments, and is formed into a thin-walled portion by being recessed radially inward. A convex ring 454 is formed on the inner side of the upper ring 452, and a groove 441 is formed on the piston rod 440 correspondingly. After the molding is completed, the convex ring 454 of the piston 450 is embedded in the groove 441 of the piston rod 440. The cooperation between the convex ring 454 and the groove 441 can help the sealing cooperation between the upper part of the piston 450 and the piston rod 440.

Claims

1. A liquid pump, comprising a pressure head, a toothed sleeve and a cylinder, wherein a piston rod is connected below the pressure head, the toothed sleeve and the cylinder are connected together, and the lower end of the piston rod extends into the interior of the cylinder, a recess is formed on the piston rod, and at least one through hole is formed in the recess extending from the outer surface of the piston rod to the inner cavity of the piston rod, It is characterized in that An elastic piston is sleeved on the recessed portion of the piston rod, and the piston comprises: a lower ring located at the lower part of the piston, the lower ring having a first outer diameter, and the lower ring is roughly in the form of a cone; and a coupling portion, the coupling portion having a second outer diameter smaller than the first outer diameter, so that the coupling portion is recessed inwardly relative to the lower ring to form a thin-walled portion, and the thin-walled portion is configured so that, in the process of the piston rod moving downward with the pressure head, the thin-walled portion is deformed to expose the through hole of the piston rod, thereby the coupling portion cooperates with the at least one through hole of the piston rod to form an upper one-way valve of the liquid pump.

2. The liquid pump according to claim 1, It is characterized in that The piston has an upper ring located at the upper part of the piston, and the coupling portion is located between the upper ring and the lower ring, wherein the upper ring has a third outer diameter, which is smaller than the first outer diameter and larger than the second outer diameter.

3. The liquid pump according to claim 2, It is characterized in that A convex ring is formed on the inner surface of the upper ring, and a first groove is formed on the piston rod. When the piston is installed on the piston rod, the convex ring is embedded in the first groove.

4. The liquid pump according to claim 1, It is characterized in that The lower ring of the piston includes a sealing surface. When the pressure head moves to the upper dead center of its stroke, the sealing surface contacts the portion of the socket extending into the cylinder.

5. The liquid pump according to claim 1, It is characterized in that The liquid pump also includes a cylinder head, which is mounted on the socket, and the lower ring of the piston includes a sealing surface. When the pressure head moves to the upper dead center of its stroke, the sealing surface contacts the part of the cylinder head that extends into the cylinder.

6. The liquid pump according to claim 1, It is characterized in that A demoulding aid is also formed on the piston, and the demoulding aid helps to peel the piston from the piston rod after the piston is formed.

7. The liquid pump according to claim 6, It is characterized in that The demolding auxiliary portion is a second groove or a protrusion formed on the upper surface of the lower ring of the piston.

8. The liquid pump according to claim 1, It is characterized in that The liquid pump further comprises a piston head, and the piston rod, the piston and the piston head are assembled together to form a piston assembly.

9. The liquid pump according to claim 1, It is characterized in that The inner wall of the cylinder is formed with: an upper raised portion, wherein when the ram is at the top dead center of its stroke, the upper raised portion contacts the piston; and / or The lower protrusion is in contact with the piston when the pressure head is at the lower dead point of its stroke.

10. A method for manufacturing a liquid pump according to any one of claims 1 to 9, It is characterized in that The piston rod and the piston are formed by the following steps: Molding the piston rod in a piston rod mold, wherein the piston rod mold includes a core mold and an outer mold; After the piston rod is manufactured, the outer mold is removed, and the mold core is retained in the manufactured piston rod; A piston mold is put on the position of the recessed portion of the piston rod to mold the piston, wherein the piston mold includes an insert extending radially inward, and the shape of the insert corresponds to the shape of the joint portion of the piston, so that the thin-walled portion is formed at the joint portion, and the thin-walled portion cooperates with the at least one through hole of the piston rod to form an upper one-way valve of the liquid pump; After the piston is manufactured, the cores of the piston mold and the piston rod mold are removed from the piston rod and the piston.

11. The method according to claim 10, It is characterized in that The piston rod is made of a first molding material, and the piston is made of a second molding material, Wherein, the molding temperature of the first molding material is higher than the molding temperature of the second molding material; and / or, the first molding material and the second molding material are difficult to adhere together.

Images