A crankshaft assembly for an electric air pump and the air pump thereof

Abstract

This invention discloses a novel connection method for crankshaft, motor output shaft, and balance weight. This patent adopts a three-piece design of crankshaft, balance weight, and expansion sleeve, which avoids weakening the cylindrical structure of the motor output shaft and ensures the rigidity of the motor output shaft. At the same time, by utilizing the uniform force compression characteristic of the expansion sleeve, the crankshaft avoids excessive clearance between the through hole on the crankshaft and the motor shaft, which would cause crankshaft misalignment.

Description

Technical Field

[0001] This invention belongs to the field of electric pumps, and particularly relates to a crankshaft assembly for an electric air pump. Background Technology

[0002] From physical and chemical experiments, food, and medical applications to energy, transportation, and chemical industries, electric air pumps or gas compressors are indispensable for the collection, transfer, and storage of various gases. Air pump structures vary widely; this patent only relates to the crankshaft structure of an electric crankshaft connecting rod piston air pump. Traditional electric crankshaft connecting rod piston air pumps mostly consist of an independent motor connected to the pump. More compact rotational power transmission methods include structures using couplings or where the motor output shaft extends into the pump crankshaft. The latter structure is relatively small and lightweight.

[0003] like Figure 1 As shown, for small air pumps, most existing crankshafts and motor shafts are fixed by screws to a local plane on the motor shaft. The machined plane on the motor shaft weakens its original strength. Furthermore, because the screws are used for unidirectional tightening, if the clearance between the through-hole on the crankshaft and the motor shaft is large, it will cause crankshaft misalignment. The rotary motion pair bearing between the crankshaft outer section and the connecting rod big end bore will oscillate, rotating non-parallel to its revolution around the motor shaft and its own rotation around the crankshaft eccentricity. Long-term operation will cause localized shaft collapse or uneven wear, deteriorating bearing operating conditions and ultimately shortening the air pump's service life.

[0004] The existing keyway connection method for large air pumps also has problems with crankshaft axial adjustment and fixation, and the keyway itself also weakens the rigidity of the motor output shaft. Summary of the Invention

[0005] The problem this invention aims to solve is to provide a novel connection method for the crankshaft, motor output shaft, and balance weight, which will not damage the cylindrical structure of the motor output shaft or cause crankshaft misalignment.

[0006] To solve the above problems, the technical solution of the present invention is:

[0007] A crankshaft assembly for an electric air pump, comprising,

[0008] The crankshaft includes an eccentric outer circular shaft section and a concentric outer circular shaft section; the crankshaft also includes a crankshaft inner hole, which passes through the eccentric outer circular shaft section and the concentric outer circular shaft section; the concentric outer circular shaft section is concentric with the crankshaft inner hole;

[0009] An expansion sleeve assembly, wherein the expansion sleeve assembly is fitted onto the concentric outer cylindrical section of the crankshaft;

[0010] A balance block, which is fitted onto the expansion sleeve assembly.

[0011] Furthermore, the eccentricity between the crankshaft inner hole and the eccentric outer circular shaft section of the crankshaft is defined as e, the radius of the eccentric outer circular shaft section of the crankshaft is defined as R, the radius of the concentric outer circular shaft section of the crankshaft is defined as r, and the design condition of the crankshaft should satisfy: e + r <= R.

[0012] Furthermore, including,

[0013] An inner cone of an expansion sleeve is fitted onto the crankshaft;

[0014] An outer cone of an expansion sleeve is fitted onto an inner cone of an expansion sleeve. The inner surface of the outer cone of the expansion sleeve is in contact with the outer surface of the inner cone of the expansion sleeve. The outer cone of the expansion sleeve is fitted with the balance block.

[0015] Furthermore, the inner cone of the expansion sleeve is evenly distributed with inner cone threaded through holes, and the outer cone of the expansion sleeve is provided with an outer cone screw through hole. The inner cone threaded through holes and the outer cone screw through holes are matched one-to-one. The inner cone of the expansion sleeve is installed inside the outer cone of the expansion sleeve by passing the expansion sleeve screw through the outer cone screw through hole and screwing it into the inner cone threaded through hole.

[0016] Furthermore, the crankshaft has an axially grooved outer circular shaft section; the number of grooves is even, and a circular hole wider than the groove is provided at the end of the groove.

[0017] An electric air pump, comprising,

[0018] A motor shaft, used to transmit motor torque;

[0019] A crankshaft includes an eccentric outer circular shaft section, a concentric outer circular shaft section, and an inner bore, wherein the inner bore passes through the eccentric outer circular shaft section and the concentric outer circular shaft section; the crankshaft is sleeved on the motor shaft;

[0020] An expansion sleeve assembly, wherein the expansion sleeve assembly is fitted onto the concentric outer circular shaft section of the shaft;

[0021] A balance block, which is fitted onto the expansion sleeve assembly;

[0022] Crankshaft bearing, wherein the crankshaft bearing is sleeved on the eccentric outer cylindrical section of the crankshaft.

[0023] A connecting rod, which is sleeved on the crankshaft bearing;

[0024] Piston assembly, the piston assembly being connected to the connecting rod;

[0025] The air pump housing, in which the piston assembly performs axial and torsional movements.

[0026] The beneficial effects of this invention are as follows: Through the newly designed sleeve connection method between the crankshaft, motor output shaft and balance block, this patent adopts a three-piece design of crankshaft, balance block and expansion sleeve, which avoids damage to the cylindrical structure of motor output shaft, and ensures the strength and rigidity of motor output shaft. At the same time, the crankshaft is evenly pressed by the expansion sleeve, which avoids crankshaft misalignment caused by a large gap between the through hole on the crankshaft and the motor shaft. Attached Figure Description

[0027] Figure 1 Diagram of existing technology structure;

[0028] Figure 2 This is a schematic diagram of the internal structure of an embodiment of the present invention;

[0029] Figure 3 This is a three-quarter view of the internal assembly structure of an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the crankshaft structure according to an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the crankshaft structure from another perspective according to an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the exploded structure of the expansion sleeve assembly according to an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram of the exploded structure of the expansion sleeve assembly according to an embodiment of the present invention;

[0034] Figure 8 This is a schematic diagram of the assembly of the crankshaft, balance weight, and expansion sleeve according to an embodiment of the present invention:

[0035] Figure 9 This is a schematic diagram of a slotted crankshaft structure according to an embodiment of the present invention;

[0036] Figure 10 This is a schematic diagram of the crankshaft structure from another perspective according to an embodiment of the present invention;

[0037] Among them, 1 is the motor shaft, 2 is the crankshaft, 2.1 is the crankshaft inner bore, 2.11 is the concentric axis, 2.21 is the eccentric axis, 2.2 is the eccentric outer cylindrical section of the crankshaft, 2.3 is the concentric outer cylindrical section of the crankshaft, 2.4 is the crankshaft transition radius (R fillet), 2.5 is the slot, 2.51 is the round hole, 3 is the expansion sleeve assembly, 3.1 is the expansion sleeve inner cone, 3.11 is the inner cone inner bore, 3.12 is the inner cone conical surface, 3.13 is the inner cone slot, 3.14 is the inner cone 3.2 Expansion sleeve outer cone, 3.21 Outer cylindrical shaft section of outer cone, 3.22 Inner cone hole of outer cone, 3.23 Groove of outer cone, 3.24 Threaded hole of outer cone, 3.3 Expansion sleeve screw, 4 Balance block, 4.1 Inner hole of balance block, 4.2 Eccentric part of balance block, 5 Crankshaft bearing, 6 Connecting rod, 7 Piston and connecting rod connecting screw, 8 Piston assembly, 9 Air pump housing, 9.1 End cover, 10 Motor body. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0039] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] Example 1

[0041] like Figure 2-8 As shown,

[0042] A crankshaft assembly for an electric air pump includes a three-piece crankshaft assembly consisting of a crankshaft 2, a balance block 4, and a standard expansion sleeve 3. The crankshaft 2 is composed of two sections: an eccentric outer circular shaft section 2.2 and a concentric outer circular shaft section 2.3, both with an interference fit to the crankshaft bearing 5, plus a transition arc 2.4. An inner bore 2.1, concentric with the concentric outer circular shaft section 2.3, passes through the eccentric outer circular shaft section 2.2. The diameter of the inner bore 2.1 is in sliding fit with the outer diameter of the motor shaft 1. If the eccentricity between the inner bore 2.1 and the eccentric outer circular shaft section 2.2 is defined as e (the distance between axes 2.11 and 2.21); the radius of the eccentric outer circular shaft section 2.2 is defined as R; and the radius of the concentric outer circular shaft section 2.3 is defined as r, the design condition of the crankshaft should satisfy: e + r <= R.

[0043] Figure 6-8 As shown, the expansion sleeve group 3 is a standard expansion sleeve, which consists of three parts: an inner cone 3.1, an outer cone 3.2, and an expansion sleeve screw 3.3.

[0044] The inner cone 3.1 of the expansion sleeve has an inner cone inner hole 3.11 that slides with the outer circular shaft section 2.3 concentric with the crankshaft; the inner cone 3.1 of the expansion sleeve also has an inner cone conical surface 3.12 that mates with the inner cone conical hole 3.22 of the outer cone of the expansion sleeve 3.2; the inner cone 3.1 of the expansion sleeve also has an inner cone slot 3.13 and an inner cone threaded hole 3.14;

[0045] The outer conical body 3.2 of the expansion sleeve is provided with an outer conical outer cylindrical shaft section 3.21, an inner conical hole 3.22, an outer conical groove 3.23, and an outer conical through hole 3.24;

[0046] The expansion sleeve screw 3.3 passes through the outer cone through hole 3.24 on the outer cone of the expansion sleeve 3.2 and is tightened one by one with the corresponding inner cone threaded hole 3.14, which shortens the axial length of the expansion sleeve group 3, while increasing the radial dimension and shrinking the inner hole.

[0047] The balance block 4 has an inner hole 4.1 and an eccentric part 4.2 for balancing the eccentric mass of the crankshaft after assembly.

[0048] The inner hole 4.1 of the balance block is transitionally fitted with the outer cylindrical shaft section 3.21 of the outer cone of the outer cone 3.2 on the expansion sleeve assembly 3.

[0049] The wall thickness formed by the concentric outer cylindrical section 2.3 of the crankshaft and the inner hole 2.1 of the crankshaft is relatively thin, making it prone to deformation.

[0050] Furthermore, when the wall thickness formed by the concentric outer cylindrical section 2.3 of the crankshaft and the inner bore 2.1 of the crankshaft is large, this section can be axially slotted 2.5 to increase deformation (see...). Figure 9 ,10), the number of slots is even, and the end of the slot is connected to a circular hole 2.51 wider than the slot to reduce stress concentration.

[0051] like Figure 2 , 3 As shown in Figure 8, an electric air pump is assembled by first pressing the inner ring of the crankshaft bearing 5 onto the eccentric outer cylindrical section 2.2 of the crankshaft 2, and then fitting a connecting rod onto the outer ring of the bearing 5. The expansion screws 3.3 on the expansion sleeve assembly 3 are in a loose state, as shown in Figure 8. Figure 8 As shown. Then, the assembled crankshaft is placed in the air pump housing, the motor shaft 1 is inserted into the crankshaft inner hole 2.1, and then the expansion sleeve assembly 3 is fitted onto the concentric outer cylindrical shaft section 2.3 of the crankshaft. Next, the balance block inner hole 4.1 on the balance block 4 is fitted onto the outer conical outer cylindrical shaft section 3.21 of the expansion sleeve assembly 3. The balance block eccentric part 4.2 of the balance block 4 is adjusted to be 180° with the maximum eccentricity of the crankshaft eccentric outer cylindrical shaft section 2.2. After axially adjusting the crankshaft 2 so that the piston center on the connecting rod is consistent with the cylinder center, the expansion sleeve screws 3.3 on the expansion sleeve assembly 3 are tightened one by one. The radial expansion of the expansion sleeve assembly 3 is restricted by the balance block inner hole 4.1 on the balance block 4, forcing the inner conical inner hole 3.11 on the inner cone 3.1 of the expansion sleeve assembly 3 to contract, thereby pressing and fixing the concentric outer cylindrical shaft section 2.3 of the crankshaft onto the motor shaft 1, thus completing the installation of the crankshaft 2 and the motor shaft 1.

[0052] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A crankshaft assembly for an electric air pump, characterized by, Comprising, a crankshaft, the crankshaft comprising, an eccentric outer circle shaft segment and a crankshaft concentric outer circle shaft segment; the crankshaft further comprising, a crankshaft inner hole, the crankshaft inner hole penetrating through the eccentric outer circle shaft segment and the crankshaft concentric outer circle shaft segment; the crankshaft concentric outer circle shaft segment is concentric with the crankshaft inner hole; an expansion sleeve set, the expansion sleeve set sleeved on the crankshaft concentric outer circle shaft segment; a balance weight, the balance weight sleeved on the expansion sleeve set; the expansion sleeve set, comprising, an expansion sleeve inner cone, the expansion sleeve inner cone sleeved on the crankshaft; an expansion sleeve outer cone, the expansion sleeve outer cone sleeved on the expansion sleeve inner cone, the inner surface of the expansion sleeve outer cone is in close contact with the outer surface of the expansion sleeve inner cone, and the balance weight is sleeved on the expansion sleeve outer cone.

2. The crankshaft assembly for an electric air pump of claim 1, wherein, The eccentric amount of the crankshaft eccentric outer circle shaft segment is defined as e, the radius of the crankshaft eccentric outer circle shaft segment is defined as R; the radius of the crankshaft concentric outer circle shaft segment is defined as r, and the design condition of the crankshaft should satisfy: e+r<=R.

3. The crankshaft assembly for an electric air pump of claim 1, wherein, The expansion sleeve inner cone is uniformly distributed with inner cone threaded through holes, the expansion sleeve outer cone is provided with outer cone screw through holes, the inner cone threaded through holes and the outer cone screw through holes are one-to-one corresponding and matched, the expansion sleeve inner cone is installed inside the expansion sleeve outer cone by the expansion sleeve screw penetrating through the outer cone screw through hole and being screwed in the inner cone threaded through hole.

4. The crankshaft assembly for an electric air pump according to any one of claims 1 to 3, wherein The crankshaft concentric outer circle shaft segment is axially slotted; the number of the slots is even, and the slots are provided with circular holes wider than the slots at the ends.

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