Piezoelectric pump multiplexing and having functions of cooling fins

Abstract

The invention relates to a multiplexing piezoelectric pump with a cooling fin function, in particular to an improved design of a piezoelectric pump for driving fluid by a piezoelectric actuator or a piezoelectric vibrator, a set of vibrator for driving the fluid is driven by the vertical reciprocating motion of piezoelectric or other electric actuating materials, and the multiplexing improved design of one set of vibrator and two piezoelectric pumps is formed by multiplexing the motion of two surfaces of the vibrator. And the flow is doubled. The possibility that the piezoelectric pump integrates the function of a cooling fin is brought by the large flow of the multiplex design, the piezoelectric pump bottom plate is made of a high-heat-conduction material and has the function of the cooling fin, the cooling fin and a corresponding flow channel can be omitted, and the thicknesses of the two parts are reduced. The method is particularly critical to application in thin electronic equipment.

Description

Technical Field

[0001] An improved design of a piezoelectric pump that uses a piezoelectric actuator or a piezoelectric vibrator to drive fluid, with a set of vibrators that reciprocate up and down using piezoelectric or other electroactive materials to drive the fluid. An improved design that multiplexes the motion on both sides of the vibrator to form two piezoelectric pumps with a set of vibrators, doubling the flow rate. The large flow rate of the multiplexed design makes it possible to integrate a heat sink function into the piezoelectric pump. The bottom plate of the piezoelectric pump is made of a highly thermally conductive material and also serves as a heat sink, eliminating the need for a heat sink and the corresponding flow channels, and reducing the thickness of these two components. This is particularly crucial for applications in thin electronic devices. Background Art

[0002] The prior art piezoelectric pump designs are as follows Figure 12 , and U.S. Patent US20230137610A1 presents a design of a piezoelectric pump. And Figure 13 in the applicant's earlier application CN2023113803233 also presents a different design. As Figure 14 , a schematic of a piezoelectric pump with a circular vibrator suspended and fixed at the edge is given. In these designs, only the motion and space below the vibrator (in one direction) are used to drive the fluid out. Analyzing, the space, motion, and energy above the vibrator are not utilized and are wasted. In fact, in order to protect the vibrator and not interfere with its motion, a suitable space and structure must be reserved above the vibrator in the existing designs to protect the upper surface of the vibrator. In the existing designs, the space above the vibrator is not utilized, nor is the energy of the upward motion. Summary of the Invention

[0003] Therefore, a piezoelectric pump as shown in Figure 1 is designed, which is equivalent to adding a mirror-symmetric structure with the vibrator as the axis of symmetry above Figure 13 , forming an air chamber above and below the vibrator. When the vibrator 1 moves downward, the lower air chamber is compressed, while the upper air chamber of the vibrator 1 is enlarged instead. When the vibrator 1 moves upward, the upper air chamber is compressed, while the lower air chamber of the vibrator 1 is enlarged instead. The compressed fluid in the upper and lower air chambers flows out on the left side, passes through the channel 5.1 inside the fixing part, and then converges into the outlet 5 and further flows into the outside. When the vibrator is driven, the upper and lower air chambers respectively become a piezoelectric pump. These two pumps, as shown in Figure 1 , are in parallel, doubling the flow rate and reducing the flow rate fluctuation. The concept of this application is: in Figure 12 , 13In the prior art designs of 14, only the lower half of the space and energy of the oscillator's movement is utilized. By simply setting a mirror-symmetrical structure on the upper part of the oscillator that is exactly the same as the structure of the original lower air chamber, two piezoelectric pumps can be obtained. The energy consumption of the oscillator remains unchanged, but the output flow rate doubles. And the thickness of the pump does not increase significantly because in the original design, a reasonable space also needs to be set on the upper part of the oscillator to protect the upper surface of the oscillator from contacting the housing and being damaged. The thickness of this part of the structure and the gap is basically equal to the thickness of the upper structure and the upper air chamber in this design. Therefore, this application is equivalent to obtaining two piezoelectric pumps with approximately the same thickness and the same power as Figure 12 , 13 and 14, with the output flow rate doubling. And there is an additional technical effect: the output is more stable. Because the two piezoelectric pumps have opposite phases, the output is like the lower half in Figure 6 , similar to the output flow rate graph of full-wave rectification. While the output of the prior art only has output in half a cycle, similar to half-wave rectification, as shown in the upper half of Figure 6 , and the stability of the output is significantly worse.

[0004] Figure 1 The piezoelectric oscillator in can be a single-arm cantilever oscillator as shown in the figure, or a double-arm cantilever or a circular oscillator with a circular center fixed as shown in Figure 2 . In these two cases, the fluid outlet 5 is located at the middle position of the entire pump. For a piezoelectric pump with a circular piezoelectric oscillator fixed by edge suspension, it can be a multiplexing design as shown in Figure 10 , with air intake at the edge of the pump body, and there is an outlet on each of the upper and lower surfaces of the pump body for the fluid of the upper and lower air chambers of the oscillator to flow out.

[0005] For further improvement, since this application sets the fluid outlet of the lower air chamber to the side wall of the pump body and flows out through the flow channel 5.1 arranged inside the fixing part 2, or as shown in Figure 11 , fluid outlets are arranged on the front and rear side walls of the pump body. Therefore, when the pump is used as a heat dissipation fluid pump, it can be as shown in Figure 1 , and the bottom plate 10 of the pump is made of a high thermal conductivity material. The outer surface of the bottom plate 10 can be provided with several convex platforms when needed to cooperate with the heat conduction plane of high-power devices such as integrated circuits that need heat dissipation. The bottom plate of the pump directly replaces Figure 12 the heat sink Heat Spreader in. In this way, not only is the thermal efficiency higher, but also the thickness is thinner because the Figure 12The middle heat sink and the flow channel between the heat sink and the nozzle reduce the total thickness by the thickness of the heat sink and the flow channel. To achieve better heat dissipation, the entire pump body can be made of highly thermally conductive materials such as aluminum, copper and their alloys, or semiconductor thermally conductive materials like silicon or thermally conductive ceramics. On the basis of the active heat dissipation of the pumped fluid, the pump body can also play a certain role in passive heat dissipation as a heat spreader. All or part of the pump housing, at least including the bottom plate or part of the bottom plate, is made of a highly thermally conductive material. This design can also be used in Figure 2 the double - arm cantilever piezoelectric pump or the circular oscillator center - supported piezoelectric pump shown in Figure 3 , 5 and 8. The outlet of the upper air chamber can be arranged on the upper surface of the pump housing as shown in Figure 11 .

[0006] If, as shown in Figure 1 , 2 , 5, 8, 9 and 11, although the fluid in the upper air chamber does not flow through the bottom plate and does not directly play the role of active heat dissipation of the fluid, when the pump body plays a heat - spreading effect, that is, when the local part (bottom plate) or the whole of the pump body is made of a highly thermally conductive material, the air flow in the upper air chamber plays a role in dissipating heat from the pump body and the piezoelectric vibrator, which is very necessary and effective. Even when the pump body is not made of a highly thermally conductive material, the upper air chamber can also effectively dissipate heat from the piezoelectric vibrator, which is very crucial for the piezoelectric vibrator operating in resonance. In CN 116249834A, a structure for dissipating heat from the piezoelectric vibrator is specifically designed to stabilize the resonance frequency of the piezoelectric vibrator. In CN 116635632A, a heat - storage component is attached outside the housing to reduce the temperature of the piezoelectric vibrator. The stability of the temperature of the piezoelectric vibrator brings the stability of the resonance frequency of the vibrator, and thus brings the high - efficiency and stability of the working efficiency of the piezoelectric vibrator.

[0007] In this application, the outlet of the lower air chamber can also be arranged on the bottom plate of the pump as in the prior art, such as shown in Figure 3 and 4 . It can also be like shown in Figure 1 , 2 , 5, 7, 8 and 9, and the fluid in the lower air chamber flows out through the flow channel 5.1 inside the fixing part 2. The outlet of the upper air chamber can be arranged as shown in all the figures. The outlets of the upper and lower air chambers can also be arranged on the side wall of the pump housing as shown in Figure 11 . Preferably, it is arranged as far away from the inlet as possible. The outlets of the upper and lower air chambers can be arranged in any way or any combination mentioned in this application or shown in the figures, or at other outlet positions set according to the form of the pump, which has no decisive influence on the multiplexing effect. However, when considering the heat - sink function, the outlet of the lower air chamber should not be arranged on the lower surface of the pump body, but on the side wall of the pump body, preferably as shown in Figure 9As shown, a relatively large outlet flow channel is provided on the side inside the pump body to increase the contact between the fluid and the pump body and improve the heat dissipation effect.

[0008] The outlet 5 can be opened on the upper surface of the pump body as shown in Figure 1 or can be opened on the lower surface of the pump body as shown in Figure 4 or can be opened on the four side walls of the pump body as shown in Figure 7 、 8 and 11, or can be discharged from the pump body on the front and / or rear side walls of the pump through the outlet flow channel inside one side of the housing as shown in Figure 9 FIG. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of the multiplexing pump and / or heat sink function of the present application.

[0010] Figure 2 is a schematic diagram of the multiplexing piezoelectric pump of the present application using a double-arm cantilever beam oscillator or a disk-shaped center-fixed oscillator.

[0011] Figure 3 is one of the schematic diagrams of the outlet setting of the present application.

[0012] Figure 4 is another schematic diagram of the outlet setting of the present application.

[0013] Figure 5 is the third schematic diagram of the outlet setting of the present application.

[0014] Figure 6 is a schematic diagram of the flow rate smoothness of the present application and the prior art.

[0015] Figure 7 is another design example of the present application, a schematic diagram of a common non-multiplexing pump bottom plate with a high thermal conductivity material and heat sink function.

[0016] Figure 8 is one of the schematic diagrams of the fluid outlet layout of the upper and lower air chambers.

[0017] Figure 9 is another schematic diagram of the layout of the two fluid outlets of the upper and lower air chambers.

[0018] Figure 10 is a schematic diagram of the multiplexing design of an edge-suspended circular oscillator piezoelectric pump.

[0019] Figure 11 is a schematic diagram in which the fluid outlets of the upper and lower air chambers are both provided on the front and / or rear side walls of the pump body.

[0020] Figure 12 is the design of the prior art US20230137610A1.

[0021] Figure 13 It is the design of the prior art CN2023113803233.

[0022] Figure 14 It is a schematic diagram of a prior art edge-suspended circular oscillator piezoelectric pump.

[0023] In the figure, 1 is a piezoelectric actuator or piezoelectric oscillator actuated by piezoelectric or other materials, 2 is a fixing member of the piezoelectric oscillator, 3 is a housing, 4 is a fluid inlet, 5 is a fluid outlet, 5.1 is a fluid passage inside the fixing member 2, 6 is a lower air chamber, 7 is an upper air chamber, 8 is an inlet air chamber, 9 is a separator, and 10 is the bottom plate of the pump body. The electrodes and the feeding circuit are omitted and not drawn. Specific embodiments

[0024] Combined with the attached Figures 1 to 11 , several specific embodiments of the present application are given to further elaborate the design concept of the present application. According to the mechanism proposed in the present application, it can be applied to various electro-actuated fluid pumps without creative labor. Embodiment 1

[0025] As Figure 1 , a piezoelectric oscillator 1 is fixed on one side inside the housing 3. There are two upper and lower fixing members 2 on the left side of the piezoelectric oscillator. Fluid flow channels 5.1 are provided inside the two fixing members 2, respectively communicating the upper and lower air chambers with the fluid outlet 5. The upper and lower spaces of the piezoelectric oscillator 1 form an upper air chamber 7 and a lower air chamber 6. A fluid inlet 4 is provided at the upper part of the right housing. An inlet air chamber 8 is formed below the inlet 4, and a separator 9 is below the air chamber 8. A fluid outlet 5 is provided on the upper surface of the left side of the pump body. When the piezoelectric oscillator swings up and down with equal amplitude, the heights of the upper and lower air chambers are both the upper or lower swing amplitude of the piezoelectric oscillator plus a safety margin of 10 - 100 microns, that is, the heights of the upper and lower air chambers can be equal. It is also possible that the heights of the upper and lower air chambers are not equal. For example, the drive of the piezoelectric oscillator is a similar square wave pulse, so that the oscillator swings downward from the free state and then returns to the free state position, and so on. At this time, the height of the upper air chamber is only the safety margin, and the height of the lower air chamber is the oscillator amplitude + safety margin. The widths of the upper and lower air chambers are equal to the length of the piezoelectric oscillator. Because the compression times of the upper and lower air chambers differ by half a cycle, so there is fluid discharged alternately in the upper and lower air chambers in one cycle, and the overall flow rate is doubled, and the flow rate stability is greatly improved. It can be referred to Figure 6 , the upper half is a schematic diagram of the flow rate of a prior piezoelectric pump changing with time, similar to the voltage waveform after half-wave rectification of alternating current. And the lower half is a schematic diagram of the flow rate of the multiplexed dual pump of the present application changing with time, similar to the voltage waveform after full-wave rectification of alternating current, and the smoothness is greatly improved.

[0026] When the oscillator is driven, it can be driven by a sine wave, square wave, triangular wave or pulsed square wave signal at the resonant frequency of the oscillator, or a signal at a non-resonant frequency can be used, or an asymmetric signal as previously applied by the applicant can be used.

[0027] When the oscillator vibrates, ultrasonic waves are excited in the pump. When the oscillator moves upward, the upper air chamber is compressed, and the fluid in the upper air chamber flows out of the outlet 5 through the right channel 5.1. When the oscillator moves downward, the lower air chamber is compressed, and the fluid in the lower air chamber flows out of the outlet 5 through the right channel 5.1. The fluids in the upper and lower air chambers are replenished from the inlet air chamber 8 and the inlet 4.

[0028] When the piezoelectric pump in this example is used for heat dissipation, it is preferred that part or all of the bottom plate of the pump and / or the outer shell of the pump is made of a high thermal conductivity material. The high thermal conductivity materials include metallic aluminum, copper and alloys, heat-conducting ceramics and semiconductor materials, etc., and also include new high thermal conductivity materials that will emerge in the future. This enables the bottom plate or the entire outer shell of the pump to simultaneously function as a heat sink. The lower surface of the bottom plate can be provided with raised platforms as required, which cooperate with the electronic components to be cooled and can be installed in the same way as a heat sink, closely attached to the electronic components. In this way, the piezoelectric pump of this design is both a piezoelectric pump for active heat dissipation and a heat sink. And the flow channel between the pump and the heat sink in the prior art Figure 12 is omitted. In this way, two thicknesses are reduced: the thickness of the heat sink + the thickness of the flow channel. And the heat dissipation effect is better because, firstly, the flow rate doubles after multiplexing, and secondly, the outer shell of the pump body can also play a certain role in heat equalization / heat dissipation, and the heat conduction is more direct. Embodiment 2

[0029] In Figure 2 it shows a schematic of a multiplexed piezoelectric pump using a double-arm cantilever beam or a circular oscillator with central support. The oscillator 1 can be a long strip piezoelectric oscillator, supported in the middle by a fixing member 2, and there is a through hole in the center of the fixing member 2 which cooperates with the opening of the outer shell and the through hole of the oscillator to form a fluid outlet 5. The fixing member 2 also has a flow channel 5.1 to communicate the upper and lower air chambers of the pump and the outlet 5. Because the compression times of the upper and lower air chambers are staggered by half a cycle, the upper and lower air chambers alternately discharge fluid in one cycle, and the overall flow rate doubles, and the flow rate stability is greatly improved. One can refer to Figure 6 where the upper half shows the schematic of the flow rate of the existing piezoelectric pump changing with time, presenting a voltage waveform similar to that after half-wave rectification of alternating current. And the lower half shows the schematic of the flow rate of the multiplexed double pump of this application changing with time, similar to the voltage waveform after full-wave rectification of alternating current, and the stability is greatly improved.

[0030] This embodiment is equivalent to Figure 1 two pumps arranged side by side on the left and right.

[0031] It can also be understood Figure 2The middle cross-section is a disc-shaped design, that is, in the figure, it is a cross-sectional view of a disc-shaped piezoelectric pump. The pump is in the shape of a disc, the piezoelectric vibrator is a disc, and the support member 2 is also two discs with a middle through-hole and an internal flow channel. The fluid outlet is at the center of the upper surface of the disc-shaped pump. As needed, the fluid outlet can also be provided on the lower surface of the pump.

[0032] Since fluids flow through both the upper and lower surfaces of the piezoelectric vibrator, taking away the heat of the vibrator, the thermal stability of the piezoelectric pump in this example is greatly improved. Embodiment 3

[0033] As Figure 7 shown, all or at least part of the outer shell of a common piezoelectric pump, and at least including all or part of the bottom plate, is made of high thermal conductivity materials such as metal aluminum, copper and their alloys, or common high thermal conductivity materials such as heat-conducting ceramics or silicon. And on the lower surface of the high thermal conductivity material part of the bottom plate 10, a raised local platform can be set as needed, which is matched with the heat conduction surfaces of the electronic components that need to dissipate heat, such as integrated circuits, power components and CPUs, etc., components that generate high heat. The installation method is similar to that of the heat sink in the prior art. When in use, these protrusions can be closely attached to the metal heat conduction surface of the component, and the bottom plate 10 simultaneously functions as a traditional heat sink. The heat of the component is efficiently conducted to the bottom plate 10, and then to the outer shell of the pump. When the fluid in the lower air chamber flows from left to right, it flows through the surface of the bottom plate 10, that is, the heat sink, and takes away the heat, and then flows out of the pump body through the outlet 5, realizing the effect of active heat dissipation of dissipating heat to the external environment. This embodiment and the prior art Figure 12 Compared, first, the thickness is different and the structure is simplified. Figure 12 In it, there are two more layers of structures below the lower surface of the pump body: one layer of flow channel and one layer of heat sink. And in this embodiment, the heat sink is directly incorporated into the high thermal conductivity material bottom plate 10 of the pump body. The bottom plate 10 is both the bottom plate of the pump and the heat sink at the same time. This design omits the heat sink and also omits a flow channel. The fluid directly flows through the surface of the bottom plate 10, which also serves as a heat sink, inside the pump body and takes away the heat. In the design of the prior art, after the fluid is pumped out of the pump body, it flows through the surface of the heat sink in the external flow channel, thereby taking away the heat. Therefore, this design can be greatly reduced in thickness, and the heat dissipation effect is better. In the application of thin-type electronic products such as mobile phones and laptop computers, the thickness is one of the key indicators of the heat dissipation piezoelectric pump. Embodiment 4

[0034] As Figure 9As shown in the figure. All or at least part of the piezoelectric pump housing, including all or part of the bottom plate, is made of a highly thermally conductive material such as common metal aluminum, copper and their alloys, or thermally conductive ceramics or silicon, or other highly thermally conductive materials that may emerge in the future. And on the lower surface of the highly thermally conductive material part of the bottom plate 10, there may be a locally raised platform when needed, which is matched with the heat conduction surfaces of electronic components that need to dissipate heat, such as integrated circuits, power components and CPUs, etc., components that generate a large amount of heat. During use, these protrusions can be closely attached to the metal heat conduction surfaces of the components. The bottom plate 10 simultaneously functions as a traditional heat sink, and the installation method is similar to that of the heat sink in the prior art. The heat of the components is efficiently conducted to the bottom plate 10 or the pump housing. When the fluid in the lower air chamber flows from left to right, it takes away heat from the bottom plate 10 and flows out of the pump body through the outlet 5. At the same time, the fluid in the upper air chamber also has an active heat dissipation effect on the pump body and the piezoelectric vibrator to reduce the temperature rise, and further improves the utility of the heat equalizer / heat dissipation plate of the pump body.

[0035] The outlet 5 is a relatively large outlet flow channel formed inside one side of the pump body, opening on the front and rear side walls of the pump (either one or both of the two front and rear side walls parallel to the paper surface). The fluid flows from the flow channel 5.1 into the outlet flow channel 5, and then flows to the outside on the front and rear side walls of the pump body, dissipating heat to the outside.

[0036] This embodiment has better performance compared with Embodiment 3. On the premise that the thickness is the same or basically the same, the flow rate is doubled, and the heat dissipation of the piezoelectric vibrator and the pump body is increased, which is beneficial to the stable operation of the piezoelectric vibrator. At the same time, the utility of the pump body as a heat sink and / or heat equalizer is improved. Embodiment 5

[0037] For the multiplexing design of a piezoelectric pump with a circular vibrator suspended at the edge as Figure 10 shown, compared with the prior art Figure 14 , it can be seen that above the piezoelectric vibrator, a fluid outlet is added on the upper surface of the housing. When the vibrator moves upward, it drives the fluid to flow out of the upper outlet, and when the vibrator moves downward, it drives the fluid to flow out of the lower outlet. Although simple, the effect is an unexpectedly significant technical effect of doubling the flow rate. And it has the technical effect of more stable operation of the vibrator, because the fluid flows horizontally across both the upper and lower surfaces of the vibrator, and the heat dissipation effect is doubled compared with the prior art.

[0038] This application can be used in the fluid pump designs of various electro-actuated actuators, such as single-arm cantilever beams or double-arm cantilever beams, circular oscillators or other special-shaped oscillators, and various fluid pumps or piezoelectric pumps. The core of the design lies in the structural mirror symmetry above and below the piezoelectric oscillator, with two air chambers and two fluid outlets being provided. By making full use of the amplitudes and energies of the two-sided motion of the oscillator, a flow rate or pressure that is twice as much can be obtained, while the energy consumption remains basically unchanged and the thickness does not increase significantly, resulting in remarkable technical effects. At the same time, the bottom plate is made of a high thermal conductivity material, which also functions as a heat sink in the prior art. An additional flow channel and heat sink are eliminated, simplifying the structure, significantly reducing the thickness, and achieving a better heat dissipation effect.

Claims

1. A multiplexed piezoelectric pump, comprising a pump body housing, a piezoelectric vibrator and its fixing member, a fluid inlet, a fluid outlet. An air chamber is formed above and below the piezoelectric vibrator respectively, and each of the two air chambers has a fluid outlet. When the piezoelectric vibrator moves upward, it drives the fluid in the upper air chamber to flow out from the fluid outlet of the upper air chamber; when the piezoelectric vibrator moves downward, it drives the fluid in the lower air chamber to flow out from the fluid outlet of the lower air chamber, achieving multiplexing of the upward and downward movements of the piezoelectric vibrator.

2. The multiplexed piezoelectric pump according to claim 1, further characterized in that the fluid of at least one of the two air chambers flows out of the pump body through a flow channel inside the fixing member.

3. The multiplexed piezoelectric pump according to claim 1, further characterized in that, the fluid of at least one of the two air chambers flows into an outlet flow channel inside the pump body through a flow channel inside the fixing member and then flows out of the pump body, or the fluid of at least one of the two air chambers flows out of the pump body through a fluid outlet on the front and / or rear side wall of the pump body.

4. A piezoelectric pump having a heat sink function, comprising a pump body housing, a piezoelectric vibrator and its fixing member, a fluid inlet, a fluid outlet. At least a part of the pump body housing, at least including the bottom plate or a part thereof, is made of a high thermal conductivity material. This part is both a part of the pump body housing and a heat sink, having all the functions of a heat sink.

5. The piezoelectric pump having a heat sink function according to claim 4, further characterized in that, an air chamber is formed above and below the piezoelectric vibrator respectively, and each of the two air chambers has an outlet. When the piezoelectric vibrator moves upward, it drives the fluid in the upper air chamber to flow out from the upper air chamber outlet; when the piezoelectric vibrator moves downward, it drives the fluid in the lower air chamber to flow out from the lower air chamber outlet, achieving multiplexing of the upward and downward movements of the piezoelectric vibrator.

6. The piezoelectric pump having a heat sink function according to claim 4, further characterized in that, an air chamber is formed above and below the piezoelectric vibrator respectively, and each of the two air chambers has an outlet. When the piezoelectric vibrator moves upward, it drives the fluid in the upper air chamber to flow out from the upper air chamber outlet; when the piezoelectric vibrator moves downward, it drives the fluid in the lower air chamber to flow out from the lower air chamber outlet, achieving multiplexing of the upward and downward movements of the piezoelectric vibrator. The fluid of at least one of the two air chambers flows out of the pump body through a flow channel inside the fixing member.

7. The piezoelectric pump having a heat sink function according to claim 4, further characterized in that, an air chamber is formed above and below the piezoelectric vibrator respectively, and each of the two air chambers has an outlet. When the piezoelectric vibrator moves upward, it drives the fluid in the upper air chamber to flow out from the upper air chamber outlet; when the piezoelectric vibrator moves downward, it drives the fluid in the lower air chamber to flow out from the lower air chamber outlet, achieving multiplexing of the upward and downward movements of the piezoelectric vibrator. The fluid of at least one of the two air chambers flows into an outlet flow channel inside the pump body through a flow channel inside the fixing member and then flows out of the pump body, or the fluid of at least one of the two air chambers flows out of the pump body through a fluid outlet on the front and / or rear side wall of the pump body.

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