CN117508886A - Pump core mechanism and pressing pump comprising same - Google Patents

Abstract

A pumping core mechanism is used for being arranged in a pressing pump and comprises a piston head and a piston sleeved on the piston head. The piston head includes a cylindrical portion and a skirt portion extending from an outer surface of the cylindrical portion and extending downwardly, forming a sandwich between the cylindrical portion and the skirt portion. The piston includes an outer ring and an inner ring connected to each other, the inner ring is inserted in the inter-layer when the piston is fitted over the piston head, and the piston is movable in an up-and-down direction with respect to the piston head such that the inner ring moves in the up-and-down direction in the inter-layer. Wherein the skirt is provided with a first sealing surface and the inner ring is provided with a second sealing surface, the first sealing surface and the second sealing surface being matched to form a seal all the time in a range between a top dead center of travel and a bottom dead center of travel of the piston relative to the piston head. The pump core mechanism of the structure can make the dimensional deviation in manufacture have no or little influence on the function of the pressing pump, thereby improving the stability of the pressing pump function. And also relates to a pressing pump comprising the pumping core mechanism.

Description

Pump core mechanism and pressing pump comprising same

Technical Field

The present invention relates to a push pump for dispensing a product, and in particular to the design of a pump core structure in the push pump.

Background

In packaging of a plurality of products such as daily chemicals, washing chemicals, food and beverage products, medicines, etc., a pressing pump is widely used for dispensing the products in a container for use by a user. The press pump can be used for dispensing flowable, semi-flowable products, and has the advantages of convenient use, dosing, and the like.

The core component of the push pump is the pump core, which is typically a part made of plastic. In use, it has been found that there are problems associated with plastic pump core parts, such as the size of the plastic parts being susceptible to changes due to factors such as ambient temperature, molding process, mold wear, etc. The dimensional change of the pump core part can cause unstable pump core function, thereby causing the problems of leakage in the pressing pump, reduced pumping capacity caused by weakening of pressing pumping force, increased air compression frequency in the using process, flooding in the axle center, no liquid discharge and the like.

At present, the conventional means for solving the dimensional change of the pump core part by the existing manufacturers mainly comprise the steps of improving the precision of a die, enhancing the monitoring of the part forming process, improving the detection rate of products and the like so as to improve the dimensional stability of the plastic part of the pump core. However, these measures on the one hand significantly increase the process complexity in the production process of the pressure pump and thus increase the production costs of the pressure pump. On the other hand, these approaches have limited improvement in dimensional stability of the pump core parts and do not completely eliminate the fluctuation in part dimensions during the manufacturing process.

Therefore, in the existing manufacturing process of the pressing pump, the problem of unstable pumping function of the pressing pump caused by the dimensional change of the plastic parts of the pump core is not fundamentally solved.

Accordingly, there is a need in the art of push pump manufacture to improve the structure of the push pump, and particularly the components in its pumping core mechanism, to address the problems in the prior art described above.

Disclosure of Invention

The present invention has been made to solve the above-mentioned problems occurring in the prior art. The object of the present invention is to provide a pumping core mechanism with an improved structure, which enables a pressing pump without affecting its pumping function due to dimensional deviations of pumping core parts.

The pump core mechanism is used for being arranged in a pressing pump and comprises a piston head and a piston sleeved on the piston head. The piston head includes a cylindrical portion and a skirt portion extending from an outer surface of the cylindrical portion and extending downwardly, forming a sandwich between the cylindrical portion and the skirt portion. The piston includes an outer ring and an inner ring connected to each other, the inner ring is inserted in the inter-layer when the piston is fitted over the piston head, and the piston is movable in an up-and-down direction with respect to the piston head such that the inner ring moves in the up-and-down direction in the inter-layer. Wherein the skirt is provided with a first sealing surface and the inner ring is provided with a second sealing surface, wherein the first sealing surface and the second sealing surface cooperate to form a seal throughout a range between a top dead center of travel and a bottom dead center of travel of the piston relative to the piston head.

In the above-described pumping mechanism including the piston head and the piston, a skirt is formed on the piston head, and the skirt of the piston head and the inner ring of the piston cooperate with each other to form a seal between the piston head and the piston. The structure has low requirements on the manufacturing precision, even if dimensional deviation in the manufacturing process has no or little influence on the function of the finally manufactured pressing pump, the stability of the function of the pressing pump can be improved, the requirements on the manufacturing are reduced, and the manufacturing cost can be reduced.

In addition, the piston head, and in particular the cylindrical portion thereof, typically needs to be made of a material having a greater hardness, but the skirt on the piston head may be made of a material other than the cylindrical portion, such as a material having a smaller coefficient of friction with the inner ring of the piston. In this way, the corresponding sensitivity of the one-way valve formed by the piston and the bore in the piston head can be improved, i.e. the one-way valve can be opened immediately upon depression and closed quickly upon removal of the pressure.

In one specific construction, a first sealing surface is formed on the inner surface of the skirt and a second sealing surface is formed on the outer surface of the inner ring, wherein one of the first and second sealing surfaces has an annular convex surface formed thereon that sealingly engages the other of the first and second sealing surfaces.

Preferably, an annular convex surface is formed at an upper portion of the second sealing surface. Alternatively, an annular convex surface is formed on a lower portion of the first sealing surface.

The annular convex surface helps to form an effective dynamic seal between the piston head and the piston and also reduces frictional resistance therebetween as the piston head and piston move relative to each other.

In one exemplary construction, the piston further includes a web connecting the outer ring with the inner ring, the web dividing the inner ring into an upper inner ring and a lower inner ring, and at least one of the following sealing surfaces is also formed in the pumping core mechanism:

a third sealing surface disposed at an upper portion of the first sealing surface and facing inwardly, wherein an upper portion of the second sealing surface is in sealing contact with the third sealing surface when the piston moves to a top dead center of travel relative to the piston head;

a fourth sealing surface formed at a position where the upper inner race is connected to the web, wherein a lower portion of the first sealing surface is in sealing contact with the fourth sealing surface when the piston moves to a stroke top dead center with respect to the piston head; and

a fifth sealing surface formed on an upper portion of the skirt and facing outwardly, wherein an upper portion of the second sealing surface is in sealing contact with the fifth sealing surface when the piston moves to a top dead center of travel relative to the piston head.

Here, the provision of the third to fifth sealing surfaces may help to further improve the seal between the piston head and the piston.

Preferably, at least one of the third, fourth and fifth sealing surfaces is a chamfer, a sphere, or a combination of chamfer and sphere.

Further, the piston head further comprises a head portion connected below the columnar portion, wherein an opening for communicating the inside and the outside of the piston head is formed between the columnar portion and the head portion, and the opening is matched with the inner ring of the piston to form a one-way valve.

Preferably, a first step is formed on the head portion and a second step is formed on a lower portion of the inner ring of the piston, the first step being in contact with the second step to prevent continued downward movement of the piston relative to the piston head when the piston moves to a stroke bottom dead center relative to the piston head. The provision of the first and second stepped portions prevents the piston from being removed from the piston head.

Preferably, the inner diameter of the inner ring is larger than the outer diameters of the columnar portion and the head portion. Thus, there is substantially no frictional resistance between the inner race and the cylindrical and head portions as the piston moves relative to the piston head.

Preferably, the outer diameter of the columnar portion is larger than the outer diameter of the head portion. Such an arrangement facilitates, on the one hand, demolding when manufacturing the piston head and, on the other hand, mounting the piston head and piston together.

The pressing pump comprises a pressing head and a tooth socket, wherein the pressing head can move along the up-down direction relative to the tooth socket, and a piston rod is arranged below the pressing head. Wherein the pump core mechanism as described above is mounted on the piston rod.

Drawings

Embodiments of the present invention will be more clearly understood from the structure shown in the accompanying drawings, in which:

fig. 1a shows a sectional view of the pressure pump according to the invention, wherein the pressure pump is in a standby state.

Fig. 1b shows a further sectional view of the pressure pump according to the invention, wherein the pressure pump is in a pressed state.

Fig. 2a shows a cross-sectional view of the piston head of the pumping mechanism of the first embodiment of the present invention.

Fig. 2b shows a perspective view of the piston head of fig. 2 a.

Fig. 3a shows a cross-sectional view of the piston of the pumping mechanism of the first embodiment of the invention.

Fig. 3b shows a perspective view of the piston of fig. 3 a.

Fig. 4a shows a cross-sectional view of the assembled pumping mechanism of the first embodiment of the present invention with the piston in its position at bottom dead center relative to the stroke of the piston head.

Fig. 4b shows another cross-sectional view of the assembled pumping mechanism of the first embodiment of the present invention with the piston in its top dead center position relative to the stroke of the piston head.

Fig. 5 shows a cross-section of a ram with a piston rod and a piston head to be mounted on the piston rod.

Fig. 6a shows a cross-sectional view of a pumping mechanism of a second embodiment of the invention with the piston in its position at bottom dead center relative to the stroke of the piston head.

Fig. 6b shows another cross-sectional view of the assembled pumping mechanism of the second embodiment of the present invention with the piston in its top dead center position relative to the stroke of the piston head.

Fig. 7a shows a cross-sectional view of a pumping mechanism of a third embodiment of the invention with the piston in its position at bottom dead center relative to the stroke of the piston head.

Fig. 7b shows another cross-sectional view of the assembled pumping mechanism of the third embodiment of the present invention with the piston in its top dead center position relative to the stroke of the piston head.

Fig. 8a shows a cross-sectional view of a pumping mechanism of a fourth embodiment of the invention with the piston in its position at bottom dead center relative to the stroke of the piston head.

Fig. 8b shows another cross-sectional view of the assembled pumping mechanism of the fourth embodiment of the present invention with the piston in its top dead center position relative to the stroke of the piston head.

Detailed Description

In order to facilitate the understanding of the invention, a specific embodiment of the press pump of the invention, in particular of the pumping core mechanism thereof, will be described in detail below with reference to the accompanying drawings. It is to be understood that the drawings illustrate only the preferred embodiments of the invention and are not to be considered limiting of the scope of the invention. Various obvious modifications, variations, equivalent substitutions of the invention will be apparent to those skilled in the art 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 fall within the scope of the invention.

In the following detailed description of the present invention, terms such as "upper", "lower", "inner", "outer" and the like are used to indicate directions and orientations based on the usual orientations of the press pump in the use state shown in the drawings, it being understood that the orientations of the press pumps may be changed in such cases as transportation, storage and the like.

< first embodiment >

Fig. 1a to 5 show a preferred structure of a first embodiment of the present invention. In which fig. 1a and 1b show cross-sectional views of a push pump 100 in a stand-by state and a depressed state, respectively.

The pressing pump 100 includes a pressing head 110 and a mouthpiece 120, and the pressing head 110 is movable in the up-down direction with respect to the mouthpiece 120. The ram 110 is provided with a piston rod 130, for example, the piston rod 130 may be connected to the lower portion of the ram 110, or the piston rod 130 may be integrally formed to the lower portion of the ram 110.

A pumping core mechanism 140 of the press pump 100 is connected to the lower end of the piston rod 130. As shown, the pumping mechanism 140 includes a piston head 150 and a piston 160, wherein the piston 160 may be sleeved on the exterior of the piston head 150, thereby forming the pumping mechanism 140.

Fig. 2a and 2b show a cross-sectional view and a perspective view, respectively, of the piston head 150, wherein the structure of the piston head 150 is more clearly shown. The piston head 150 includes a cylindrical portion 151 and a skirt portion 152, the skirt portion 152 extending from an outer surface of the cylindrical portion 151 and extending downwardly, a downwardly opening shelf 153 being formed between the cylindrical portion 151 and the skirt portion 152.

The piston head 150 further includes a head 154, the head 154 being connected below the pillar 151, and an opening 157 being formed between the pillar 151 and the head 154. The opening 157 communicates the exterior and interior of the piston head 150, cooperating with an inner ring 162 of the piston 160, to form a one-way valve, as will be described in greater detail below.

The piston head 150 provided with the skirt 152 is particularly advantageous for the above-described one-way valve. Specifically, the cylindrical portion 151 of the piston head 150 needs to be made of a harder material, such as PP (polypropylene) material, while the skirt 152 may be made of a softer material, such as PE (polyethylene) material, as with the piston 160. When assembled together, the inner ring 162 of the piston 160 does not have to contact the outer surface of the cylindrical portion 151, but contacts the skirt portion 152, which reduces frictional resistance between the piston head 150 and the piston 160, thereby improving the sensitivity of the check valve.

Fig. 3a and 3b show a cross-sectional view and a perspective view of the piston 160, respectively, so that the structure of the piston 160 is more clearly shown. The piston 160 includes an outer race 161 and an inner race 162 that are coupled to each other. The outer race 161 is capable of an interference fit with the cylinder wall of the compression pump 100, as in prior compression pumps, and will not be described in detail herein. The inner race 162 is configured to fit over the piston head 150, thereby mounting the piston 160 to the piston head 150, with the piston head 150 and the piston 160 being movable in an up-and-down direction relative to each other. An inner ring 162 of the piston 160 is inserted in the sandwich 153, and the inner ring 162 moves in the sandwich 153 when the piston 160 moves in the up-down direction with respect to the piston head 150.

Fig. 4a and 4b show cross-sectional views of the piston head 150 and the piston 160 mounted together, wherein fig. 4a shows the piston 160 in its bottom dead center position of travel relative to the piston head 150 and fig. 4b shows the piston 160 in its top dead center position of travel relative to the piston head 150. Wherein the inner surface of the skirt 152 of the piston head 150, i.e. the surface facing the inner ring 162 of the piston 160, constitutes the first sealing surface 155 and the outer surface of the inner ring 162 of the piston 160 constitutes the second sealing surface 163. The first sealing surface 155 cooperates with the second sealing surface 163 to form a seal between the piston head 150 and the piston 160. Also, as can be seen in the figures, the skirt 152 and inner ring 162 are configured and dimensioned such that the first sealing surface 155 and the second sealing surface 163 always cooperate with each other to form a seal, i.e., the seal between the piston head 150 and the piston 160 is always present, in the range between top dead center and bottom dead center of travel of the piston 160 relative to the piston head 150.

Preferably, an annular convex surface is formed on one of the first sealing surface 155 and the second sealing surface 163 that forms a sealing engagement with the other of the first sealing surface 155 and the second sealing surface 163 to form a more effective dynamic seal. Moreover, the provision of an annular convex surface also facilitates reducing frictional resistance between piston head 150 and piston 160 as piston 160 and piston head 150 move in an up-and-down direction relative to one another. For example, in the exemplary configuration shown in fig. 4a and 4b, an annular convex surface 164 is formed on the upper portion of inner race 162, preferably on the top portion of inner race 162. In this way, the piston 160 remains sealed when it is at its bottom dead center of travel relative to the piston head 150, i.e., when only the upper portion of the second sealing surface 163 of the inner race 162 contacts the first sealing surface 155 on the skirt 152, thereby ensuring that a seal between the piston head 150 and the piston 160 is always present.

Preferably, as shown in fig. 4a and 4b, an inwardly facing third sealing surface 156 is also formed at an upper portion of the first sealing surface 155. As the piston 160 moves to its top dead center of travel relative to the piston head 150, a corresponding portion on the inner ring 162, such as the top of the inner ring 162, will be in sealing contact with the third sealing surface 156. Thereby, the sealing effect between the piston head 150 and the piston 160 can be further improved.

As shown, the third sealing surface 156 is preferably beveled. In addition, the third sealing surface 156 may take other forms, for example, the third sealing surface 156 may be spherical or an arcuate transition surface of varying diameter.

Returning to fig. 2a and 3a, it can be seen that a first step 158 (fig. 2 a) is formed on the head 154 of the piston head 150, and correspondingly a second step 165 is formed on the lower portion of the inner race 162 of the piston 160. When the piston 160 is at its bottom dead center of travel relative to the piston head 150, the second step 165 and the first step 158 cooperatively abut each other, thereby preventing continued downward movement of the piston 160 relative to the piston head 150 from disengaging from the piston head 150. Also, the fit between the second step 165 and the first step 158 may also act as a seal.

Preferably, the inner diameter of the inner ring 162 of the piston 160 is set to be larger than the outer diameter of the piston head 150, particularly the outer diameter of the cylindrical portion 151, so that no frictional resistance is generated between the inner ring 162 and the cylindrical portion 151/head 154 when the piston 160 moves relative to the piston head 150. Thus, relative movement between the piston 160 and the piston head 150 may be facilitated, as well as reduced wear on the various components of the pumping core mechanism 140 during use.

Preferably, the outer diameter A of the cylindrical portion 151 of the piston head 150 is designed to be greater than the outer diameter B of the head 154. Such a design facilitates demolding during manufacture of the piston head 150. Moreover, during installation of the piston 160 to the piston head 150, the piston 160 is sleeved onto the piston head 150 from the direction of the head 154, so that making the outer diameter of the head 154 smaller may facilitate assembly of the piston 160 and the piston head 150 together.

In the preferred construction shown in the figures, the pumping core mechanism 140 is mounted to the piston rod 130 by the engagement of the piston head 150 with the piston rod 130. As shown in fig. 5, a plurality of concave rings 159 may be provided on the inner surface of the cylindrical portion 151 of the piston head 150, and a plurality of convex rings 131 may be provided on the outer surface of the lower portion of the piston rod 130, accordingly. The female and male rings 159, 131 can be snap fit to each other, thereby connecting the piston head 150 to the piston rod 130.

The operation principle of the pressing pump 100 of the above-described structure will be described in detail.

When the pressing pump 100 is pressed downward, the ram 110 of the pressing pump 100 is pressed to move downward, so that the piston rod 130 and the piston head 150 connected to the piston rod 130 also move downward. At this time, for the piston 160, there is friction between its outer ring 161 and the cylinder wall, so the piston 160 remains stationary relative to the cylinder and moves upward relative to the piston head 150. During this process, the opening 157 in the piston head 150 is exposed, so that the one-way valve is opened. Since the second sealing surface 163 includes the annular convex surface 164, only the annular convex surface 164 contacts the first sealing surface 155 when the piston 160 moves upward relative to the piston head 150, thereby reducing the resistance to movement between the piston 160 and the piston head 150.

Then, as the piston 160 moves to its top dead center of travel relative to the piston head 150, the top of the inner ring 162 contacts the third sealing surface 156 and the piston 160 will move downward with the piston head 150 relative to the cylinder. As the piston 160 moves downwardly relative to the cylinder, the pressure pressing against the product within the pump 100 increases, thereby exerting an upward thrust on the piston 160, which in turn compresses the sealing contact between the upper portion of the inner ring 162 of the piston 160 and the third sealing surface 156.

When the pressing force applied to the ram 110 is removed, the ram 110 will be reset upward. At this time, the piston 160 is held stationary with respect to the cylinder by friction between the outer ring 161 of the piston 160 and the cylinder wall, and moves downward with respect to the piston head 150. Thus, the upper portion of the inner race 162 is out of contact with the third sealing surface 156, but the first sealing surface 155 and the second sealing surface 163 remain in sealing contact at all times. When the second stepped portion 165 of the piston 160 abuts the first stepped portion 158 of the piston head 150, the opening 157 is covered by the inner ring 162, so that the check valve closes and the piston 160 will move upward with the piston head 150. In the process, as the piston 160 moves upward relative to the cylinder, the space within the cylinder becomes larger, creating negative pressure that draws the product in the container into the cylinder for the next use.

< second embodiment >

Fig. 6a and 6b show the structure of a pumping core mechanism of a second embodiment of the present invention. The specific structure described above with respect to the first embodiment is also applicable to the second embodiment without contrary description or conflict. The structure of the second embodiment different from the first embodiment will be specifically described below.

As in the first embodiment, in the second embodiment, the pumping mechanism includes a piston head 250 and a piston 260 mounted together, wherein the piston 260 is sleeved on the piston head 250. The piston head 250 includes a cylindrical portion 251 and a skirt 252 depending from the cylindrical portion 251 and extending downwardly. The inner ring 262 of the piston 260 is movable up and down in the sandwich between the cylindrical portion 251 and the skirt portion 252.

Unlike the first embodiment, in the second embodiment, an annular convex surface 253 is formed on the inner surface of the skirt 252. As the inner ring 262 moves in a sandwich between the cylindrical portion 251 and the skirt portion 252, the annular convex surface 253 contacts the outer surface of the inner ring 262, thereby effecting a dynamic seal between the piston head 250 and the piston 260.

Preferably, an annular convex surface 253 is provided at or near the lower end of the inner surface of the skirt 252. In this way, it is ensured that a seal is always present between the piston head 250 and the piston 260.

< third embodiment >

Fig. 7a and 7b show the structure of a pump core mechanism of a third embodiment of the present invention. The specific structures described above with respect to the first and second embodiments are also applicable to the third embodiment without contrary description or conflict. The structure of the third embodiment different from the first and second embodiments will be specifically described below.

In a third embodiment, the pumping mechanism includes a piston head 350 and a piston 360. The inner ring 362 is divided into an upper inner ring 365 and a lower inner ring 366. Specifically, a web 367 connecting the outer race 361 and the inner race 362 serves as a boundary between the upper inner race 365 and the lower inner race 366. The inner surface of the skirt 352 forms a first sealing surface 355 and the outer surface of the upper inner race 365 forms a second sealing surface 363.

Further, in the third embodiment, a fourth sealing surface 364 is formed at the connection between the upper inner race 365 and the web 367. The fourth sealing surface 364 is preferably beveled. When the piston 360 moves relative to the piston head 350 to its top dead center position, a corresponding portion of the first sealing surface 355, such as the lower portion of the first sealing surface 355, will abut the fourth sealing surface 364, thereby achieving an additional sealing effect.

Of course, the fourth sealing surface 364 may take other forms other than a beveled surface, such as a spherical surface, or an arcuate transition surface of varying diameter, etc.

< fourth embodiment >

Fig. 8a and 8b show the structure of a pumping core mechanism of a fourth embodiment of the present invention. The specific structures described above with respect to the first to third embodiments are also applicable to the fourth embodiment without contrary description or conflict. The structure of the fourth embodiment different from the first to third embodiments will be specifically described below.

In the fourth embodiment, the pumping mechanism includes a piston head 450 and a piston 460. Wherein an upper portion of a skirt 452 of the piston head 450 is formed with an outwardly facing fifth sealing surface 453, the fifth sealing surface 453 being formed, for example, at a location where the cylindrical portion 451 and the skirt 452 are connected.

When the piston 460 moves relative to the piston head 450 to its top dead center position, a corresponding portion of the piston 460, such as an upper portion of the inner race 462, particularly near its top portion, will abut the fifth sealing surface 453, thereby achieving an additional sealing effect.

In the structure shown in the drawing, the fifth sealing surface 453 is a slope. In addition, the fifth sealing surface 453 can be another type of surface, such as a spherical surface, or an arcuate transition surface of varying diameter, etc.

Claims (11)

1. The pump core mechanism is arranged in the pressing pump and comprises a piston head and a piston sleeved on the piston head, and is characterized in that,

the piston head includes a cylindrical portion and a skirt portion extending from an outer surface of the cylindrical portion and extending downward, forming a sandwich between the cylindrical portion and the skirt portion; and

the piston comprises an outer ring and an inner ring which are connected with each other, when the piston is sleeved on the piston head, the inner ring is inserted into the interlayer, and the piston can move up and down relative to the piston head, so that the inner ring moves up and down in the interlayer;

wherein the skirt is provided with a first sealing surface and the inner ring is provided with a second sealing surface, wherein the first sealing surface and the second sealing surface cooperate to form a seal throughout a range between a top dead center of travel and a bottom dead center of travel of the piston relative to the piston head.

2. The pumping mechanism of claim 1, wherein the first sealing surface is formed on an inner surface of the skirt and the second sealing surface is formed on an outer surface of the inner ring, wherein one of the first sealing surface and the second sealing surface has an annular convex surface formed thereon that sealingly engages the other of the first sealing surface and the second sealing surface.

3. A pumping mechanism according to claim 2, wherein the annular convex surface is formed in an upper portion of the second sealing surface.

4. A pumping mechanism according to claim 2, wherein the annular convex surface is formed in a lower portion of the first sealing surface.

5. The pumping mechanism of claim 1, wherein the piston further comprises a web connecting the outer ring with the inner ring, the web dividing the inner ring into an upper inner ring and a lower inner ring, and wherein at least one of the following sealing surfaces is further formed in the pumping mechanism:

a third sealing surface disposed on an upper portion of the first sealing surface and facing inwardly, wherein an upper portion of the second sealing surface is in sealing contact with the third sealing surface when the piston moves to a top dead center of travel relative to the piston head;

a fourth sealing surface formed at a position where the upper inner race is connected to the web, wherein a lower portion of the first sealing surface is in sealing contact with the fourth sealing surface when the piston moves to a stroke top dead center with respect to the piston head; and

a fifth sealing surface formed on an upper portion of the skirt and facing outwardly, wherein an upper portion of the second sealing surface is in sealing contact with the fifth sealing surface when the piston moves to a top dead center of travel relative to the piston head.

6. The pumping mechanism of claim 5, wherein at least one of the third sealing surface, the fourth sealing surface, and the fifth sealing surface is a chamfer, a sphere, or a combination of chamfer and sphere.

7. The pumping mechanism of claim 1, wherein said piston head further comprises a head portion connected below said cylindrical portion, wherein an opening is formed between said cylindrical portion and said head portion to communicate the interior and exterior of said piston head, said opening cooperating with said inner ring of said piston to form a one-way valve.

8. The pumping mechanism of claim 7, wherein a first step is formed on the head and a second step is formed on a lower portion of the inner race of the piston, the first step contacting the second step when the piston moves to a bottom dead center of travel relative to the piston head, preventing the piston from continuing downward movement relative to the piston head.

9. The pumping mechanism of claim 8, wherein an inner diameter of the inner ring is greater than an outer diameter of the cylindrical portion and the head portion.

10. The pumping mechanism of claim 8, wherein an outer diameter of the cylindrical portion is greater than an outer diameter of the head portion.

11. A pressing pump comprising a pressing head and a dental socket, wherein the pressing head is movable in an up-down direction relative to the dental socket, and a piston rod is provided below the pressing head, characterized in that the pump core mechanism according to any one of claims 1 to 10 is mounted on the piston rod.