Symmetrical multi-cylinder air compressor

Abstract

The invention provides a symmetric multi-cylinder air compressor, and belongs to the technical field of air compressors. The symmetric multi-cylinder air compressor mainly comprises an air compressor shell, a driving motor and a crankshaft piston structure, the air compressor shell is of a symmetrical split type structure and comprises a motor shell, a connecting support, a crankshaft box body and an air cylinder body, a connecting sleeve and an air cylinder support are formed at the two ends of the connecting support respectively, and a C-shaped bottom foot connecting lug is formed on the connecting sleeve and matched with the quick connecting bottom foot. A fastening end face is milled on a driving shaft of the driving motor; the crankshaft piston structure comprises a main shaft bearing, a first crankshaft, a pair of piston connecting rods and a second crankshaft, pin holes are formed in different positions of the first crankshaft and the second crankshaft, and fastening pins penetrate through the pin holes to abut against fastening end faces to achieve relative fixed connection. The multi-cylinder air compressor has the advantages of being convenient to disassemble, install, overhaul and replace, capable of improving the output air pressure and flow of the multi-cylinder air compressor, reducing the production and machining procedures, improving the machining efficiency, flexible and diverse in installation form and high in practicability.

Description

Technical Field

[0001] The invention belongs to the technical field of air compressors, and in particular relates to a symmetrical multi-cylinder air compressor. Background Art

[0002] Air compressor is abbreviated as air compressor, which is a device used to compress gas. Among them, the number of cylinders of the air compressor mainly affects the output pressure and flow of the air compressor. The more cylinders there are, the higher the output pressure and flow of the air compressor are usually. Therefore, multi-cylinder air compressors are often widely used in many industries and fields such as machinery manufacturing, metallurgical industry, light industry, electronic precision instrument industry, chemical industry, etc. However, at the same time, multi-cylinder air compressors also have problems such as high processing cost, large space occupation, inconvenient installation, and high repair and maintenance costs.

[0003] According to a multi-cylinder air compressor disclosed in the patent with announcement number CN109519354A, four cylinder bodies are arranged on the motor so that when the output shaft of the motor is in motion, four connecting rods and the piston body can be driven to move together, thereby increasing the air output while reducing the occupied space of the multi-cylinder air compressor. The four cylinder bodies are arranged symmetrically in the upper and lower parts, and the mounting feet are located on one side of one of the cylinder bodies, so that when the air compressor is running, the vibration direction of the entire body is in the vertical direction, thereby improving the overall running stability.

[0004] This patent solves some of the problems existing in multi-cylinder air compressors to a certain extent, but the following problems still exist: First, its mounting foot is a single-sided fixed foot, which cannot be installed and adjusted according to the actual application environment and installation requirements; second, its air compressor assembly is an integrated design of the crankcase and the cylinder body. If a fault occurs inside the air compressor, it is not convenient for inspection and maintenance; third, the upper and lower piston connecting rods located on one side of the motor are both mounted on the same eccentric balance block. Therefore, when the motor output shaft is running, the piston movement of the upper and lower cylinders cannot achieve synchronous gas intake, compression and discharge, but run in staggered order, and the output air pressure and flow rate are not maximized. Summary of the invention

[0005] The purpose of the present invention is to provide a symmetrical multi-cylinder air compressor in view of the above-mentioned problems existing in the prior art.

[0006] The object of the present invention can be achieved by the following technical solutions: A symmetrical multi-cylinder air compressor mainly includes an air compressor housing, an active motor and a crankshaft piston structure; The air compressor housing is a split structure, including a motor housing, a connecting bracket, a crankcase and a cylinder body; the outer diameters of both ends of the motor housing are reduced to form symmetrical housing sleeves, and the connecting bracket and the crankcase are sequentially installed and connected on both sides with the motor housing as the center; The connecting bracket is formed with a connecting sleeve sleeved on the outside of the casing sleeve on the side facing the motor housing, and a bracket partition layer with four corners extending outward is formed at the end of the connecting sleeve sleeve connection, and the outer edges of the four corners of the bracket partition layer are integrally extended toward the side facing the crankcase to form a cylinder bracket, and two cylinder columns are formed on each cylinder bracket, and a nearly circular bracket piston groove is formed between the front and rear groups of cylinder brackets. The cylinder bracket is installed and connected to the cylinder body through the cylinder column and the bracket piston groove, and C-shaped semi-open base foot connecting ears are formed on the front and rear outer walls of the middle section of the connecting sleeve, and the base foot connecting ears cooperate with the quick-connect base feet to realize quick-connect installation; the crankcase is a hood-shaped structure as a whole, and box piston grooves are provided on the front and rear sides thereof corresponding to the bracket piston grooves; The active motor is coaxially installed inside the motor housing, and active shafts are extended from both ends of the active motor, and fastening end faces are milled on the active shafts on both sides; The crankshaft piston structure is sleeved on the driving shaft of the driving motor and installed inside the connecting bracket and the crankcase. Its structure includes a main shaft bearing, a first crankshaft, a pair of piston connecting rods arranged in front and back oppositely, and a second crankshaft. The piston bearing is installed in the big head ring of the piston connecting rod; The first crankshaft and the second crankshaft are both two-section structures, with the western end with a smaller outer diameter extending into the center of the piston bearing for matching connection, and the thick end with a larger outer diameter protruding on one side to form a counterweight block, and a main shaft hole deviating from the crankshaft axis is opened inside the crankshaft near the counterweight block. The difference between the first crankshaft and the second crankshaft is that the first crankshaft has a pin hole extending through the main shaft hole at the counterweight block, and the second crankshaft has a pin hole extending through the main shaft hole on the opposite side of the counterweight block, and locking pins are installed in the pin holes. After the crankshaft piston structure is installed, the bottom surface of the locking pin abuts against the locking end surface of the driving shaft, thereby realizing the relative connection between the crankshaft and the piston connecting rod.

[0007] In the above-mentioned symmetrical multi-cylinder air compressor, a central bearing hole is provided at the center of the bracket partition layer coaxially with the driving shaft of the driving motor, and a main shaft bearing sleeved on the driving shaft is mounted in the central bearing hole.

[0008] In the above-mentioned symmetrical multi-cylinder air compressor, screw mounting holes are respectively provided at the four corners extending from the bracket partition layer, and the connecting brackets on both sides of the motor housing are relatively fixed by connecting screws passing through the screw mounting holes on both sides.

[0009] In the above-mentioned symmetrical multi-cylinder air compressor, the cylinder bracket is provided with bracket connecting holes at the arc-shaped transition connection on the upper and lower sides, and the upper and lower sides of the crankcase are provided with case connecting holes corresponding to the bracket connecting holes. The connecting bracket and the crankcase are fixedly connected to each other by bolts passing through the bracket connecting holes and the case mounting holes.

[0010] In the above-mentioned symmetrical multi-cylinder air compressor, a quick-connect convex ring is formed on the C-shaped inner wall of the base connecting ear; the quick-connect base includes a base center column and a positioning nut, a nut gasket and an elastic clamping block sleeved thereon, and the positioning nut and the nut gasket are grouped, each arranged at the upper and lower ends of the elastic clamping block and the end of the base center column close to the installation plane when the air compressor is installed; the elastic clamping block is made of elastic shock-absorbing material, and an annular quick-connect groove is opened in the middle section, and the quick-connect groove cooperates with the quick-connect convex ring to realize an adjustable quick-connect installation between the quick-connect base and the base connecting ear.

[0011] In the above-mentioned symmetrical multi-cylinder air compressor, the first crankshaft and the second crankshaft are both provided with a penetrating main shaft hole, a material reduction hole and a weight reduction hole inside, and the main shaft hole, the weight reduction hole and the counterweight block are located in a straight line, and the material reduction holes are symmetrically distributed on both sides of the main shaft hole and the weight reduction hole; the pin hole of the first crankshaft passes through the counterweight block to the main shaft hole, and the pin hole of the second crankshaft passes through the weight reduction hole from the opposite side of the counterweight block to the main shaft hole.

[0012] In the above-mentioned symmetrical multi-cylinder air compressor, the air compressor housing is centered on the active motor. By adjusting the relative positions of the first crankshaft, the second crankshaft and the piston connecting rod on the active shaft in the crankshaft-piston structure, the axially symmetrical installation or the centrally symmetrical installation of the multi-cylinder air compressor can be achieved respectively.

[0013] Compared with the prior art, the symmetrical multi-cylinder air compressor provided by the present invention has the following advantages: 1. The quick-connect foot and the air compressor housing are quickly connected by the quick-connect foot and the foot connecting ear, which is convenient for installation and disassembly. At the same time, the quick-connect foot can adjust the relative position of the elastic clamping block on the center column of the foot to adjust the installation height of the multi-cylinder air compressor as a whole on the installation plane; 2. The air compressor housing is a split structure. If a fault occurs inside the multi-cylinder air compressor, it is easy to disassemble the connecting bracket or crankcase separately to inspect and replace the inside of the motor or crankcase; 3. The first crankshaft and the second crankshaft are respectively installed in cooperation with the piston connecting rod, so that the piston connecting rods arranged opposite to each other are installed in a staggered manner. Therefore, when the active motor drives the active shaft to run, the piston movement in the multiple cylinder bodies on the front and rear sides can realize the synchronous inhalation, compression and discharge of gas, which greatly improves the output pressure and flow of the multi-cylinder air compressor; Fourth, by setting different pin hole positions on the first crankshaft and the second crankshaft, the locking pin can be located on the same side of the driving shaft during the matching installation. Therefore, during production and processing, the driving shaft only needs to mill out one locking end face, and there is no need to mill out the two opposite sides, which reduces the processing procedures and improves the processing efficiency of the active motor; 5. This multi-cylinder air compressor can be selected as an axisymmetric or center-symmetrical multi-cylinder air compressor according to actual installation requirements. The multi-cylinder air compressor can also be flipped or horizontally rotated by adjusting the quick-connect base feet. The installation form is flexible and diverse, and it is highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the overall structural diagram of the symmetrical multi-cylinder air compressor; Figure 2 This is a partial structural exploded diagram of the air compressor housing in this symmetrical multi-cylinder air compressor; Figure 3 This is a structural explosion diagram of the active motor and crankshaft piston structure in this symmetrical multi-cylinder air compressor; Figure 4 This is a sectional view of the overall structure of the first embodiment of the symmetrical multi-cylinder air compressor; Figure 5 It is a sectional view of the overall structure of the second embodiment of the symmetrical multi-cylinder air compressor.

[0015] In the above figure, 1, air compressor housing; 11, motor housing; 111, housing sleeve; 12, connecting bracket; 121, connecting sleeve; 122, bracket partition layer; 1221, center bearing hole; 1222, screw mounting hole; 123, cylinder bracket; 1231, cylinder column; 1232, bracket piston groove; 1233, bracket connecting hole; 124, foot connecting ear; 1241, quick-connect convex ring; 125, connecting screw; 13, crankcase; 131, case piston groove; 132, case connecting hole; 14, cylinder body; 2. Active motor; 21. Active shaft; 211. Fixing end face; 3. Crankshaft piston structure; 31. Spindle bearing; 321. First crankshaft; 322. Second crankshaft; 3201. Spindle hole; 3202. Material reduction hole; 3203. Weight reduction hole; 3204. Counterweight; 3205. Pin hole; 33. Piston connecting rod; 331. Piston bearing; 34. Fixing pin; 4. Quick-connect foot; 41. Center column of foot; 42. Positioning nut; 43. Nut gasket; 44. Elastic block; 441. Quick-connect groove. DETAILED DESCRIPTION

[0016] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0017] Embodiment 1: like Figures 1 to 4As shown, a symmetrical multi-cylinder air compressor mainly includes an air compressor housing 1, an active motor 2 and a crankshaft piston structure 3, and the active motor 2 and the crankshaft piston structure 3 are both arranged inside the air compressor housing 1. In the first embodiment, the air compressor housing 1 is symmetrically installed with the active motor 2 as the center.

[0018] like Figure 2 As shown, the air compressor housing 1 is a split structure as a whole, including a motor housing 11, a connecting bracket 12, a crankcase 13 and a cylinder body 14. If a fault occurs inside the multi-cylinder air compressor, it is convenient to disassemble the connecting bracket 12 or the crankcase 13 to inspect and replace the inside of the motor or the crankcase. The outer diameters of the two ends of the motor housing 11 are reduced to form symmetrical casing sleeves 111, and a number of ventilation grooves are spaced apart on the annular protrusion in the middle. The two ends of the motor housing 11 are symmetrically installed and connected with the connecting bracket 12 and the crankcase 13 on both sides with the motor housing 11 as the axis of symmetry. The ventilation groove can provide an airflow channel between the connecting brackets 12 on both sides for ventilation and heat dissipation after the multi-cylinder air compressor is assembled and connected.

[0019] The connecting bracket 12 is formed with a connecting sleeve 121 on the side facing the motor housing 11. The connecting sleeve 121 is sleeved on the outside of the housing sleeve 111 to facilitate the combined installation between the motor housing 11 and the connecting bracket 12. The connecting bracket 12 is formed with a bracket partition layer 122 extending outward at four corners at the end where the connecting sleeve 121 is sleeved. The center of the bracket partition layer 122 is coaxially provided with a central bearing hole 1221 coaxially with the driving shaft 21 of the driving motor 2, and a number of heat dissipation and material reduction fan-shaped holes are uniformly provided on the bracket partition layer 122 with the central bearing hole 1221 as the center. The bracket partition layer 122 not only supports the connecting bracket 12 to ensure the overall structural strength, but also the central bearing hole 1221 opened in the center thereof also assists in the coaxial installation of other internal structures. Screw mounting holes 1222 are respectively provided at the four corners extending from the bracket partition layer 122 , and the connecting brackets 12 on both sides of the motor housing 11 are penetrated between the screw mounting holes 1222 on both sides through the connecting screws 125 , thereby achieving relative fixation between the connecting brackets 12 .

[0020] The outer edges of the four corners of the bracket partition layer 122 extend integrally toward the side facing the crankcase 13 to form cylinder brackets 123, each of which has two cylinder columns 1231 formed thereon, and a nearly circular bracket piston groove 1232 is formed between the front and rear groups of cylinder brackets 123. The cylinder column 1231 is used to connect the cylinder head of the cylinder body 14, and the bracket piston groove 1232 is used to accommodate the piston connecting rod 33 for piston movement, and its edge is connected to the tubular side wall of the cylinder body 14, so that the cylinder bracket 123 is installed and connected to the cylinder body 14 through the cylinder column 1231 and the bracket piston groove 1232.

[0021] A C-shaped semi-open foot connection ear 124 is formed on the front and rear outer walls at the middle section of the connecting sleeve 121, and a quick-connect convex ring 1241 is formed on the C-shaped inner wall of the foot connection ear 124. The quick-connect foot 4 includes a foot center column 41 and a positioning nut 42, a nut gasket 43 and an elastic clamping block 44 sleeved thereon. The positioning nut 42 and the nut gasket 43 are grouped and are respectively arranged at the upper and lower ends of the elastic clamping block 44 and at one end of the foot center column 41 close to the installation plane when the air compressor is installed. The elastic clamping block 44 adopts elastic shock-absorbing material, which can reduce the vibration of the multi-cylinder air compressor during operation. An annular quick-connect groove 441 is provided at the middle section of the elastic clamping block 44. The quick-connect groove 441 cooperates with the quick-connect convex ring 1241 to realize the quick-connect installation between the quick-connect foot 4 and the foot connection ear 124, which is convenient for installation and disassembly, and realizes the flip or horizontal rotation installation of the multi-cylinder air compressor. The installation form is flexible and diverse, and the practicability is strong.

[0022] At the same time, the elastic block 44 is sandwiched on the center column 41 of the base. When the multi-cylinder air compressor is located on different installation planes, the quick-connect base 4 can realize the relative position of the elastic block 44 on the center column 41 of the base by screwing the positioning nuts 42 and nut washers 43 on both sides of the elastic block 44, thereby realizing the adjustable installation height of the multi-cylinder air compressor as a whole on the installation plane. The crankcase 13 is a hood-shaped structure as a whole, and a case piston groove 131 is provided on the front and rear sides thereof, and the case piston groove 131 corresponds to the bracket piston groove 1232 and cooperates with each other to accommodate the piston connecting rod 33 to perform piston movement. The cylinder bracket 123 is provided with a bracket connecting hole 1233 at the arc-shaped transition connection on the upper and lower sides, and a case connecting hole 132 is provided on the upper and lower sides of the crankcase 13 corresponding to the bracket connecting hole 1233, and the connecting bracket 12 and the crankcase 13 are fixedly connected to each other by bolts penetrating the bracket connecting hole 1233 and the case mounting hole.

[0023] like Figure 3 to Figure 4 As shown, the active motor 2 is coaxially installed inside the motor housing 11, and the two ends of the active motor 2 are extended with active shafts 21, and the active shafts 21 on both sides are milled with fixing end faces 211. The crankshaft piston structure 3 is sleeved on the active shaft 21 of the active motor 2 and installed inside the connecting bracket 12 and the crankcase 13. Its structure includes a main shaft bearing 31, a first crankshaft 321, a pair of piston connecting rods 33 and a second crankshaft 322 arranged in reverse front and back. The main shaft bearing 31 is installed in the central bearing hole 1221 of the bracket partition layer 122, and the piston connecting rod 33 is installed with a piston bearing 331 in the big head ring.

[0024] The first crankshaft 321 and the second crankshaft 322 are both two-stage structures, with the western end with a smaller outer diameter extending into the center of the piston bearing 331 for matching connection, and the thick end with a larger outer diameter protruding on one side to form a counterweight block 3204, and a main shaft hole 3201 deviating from the axis of the crankshaft is provided in the crankshaft near the counterweight block 3204, and a through-hole 3202 and a weight-reducing hole 3203 are also provided in the first crankshaft 321 and the second crankshaft 322, the main shaft hole 3201, the weight-reducing hole 3203 and the counterweight block 3204 are located in a straight line, and the weight-reducing holes 3202 are symmetrically distributed on both sides of the main shaft hole 3201 and the weight-reducing hole 3203. The driving shaft 21 is provided in the main shaft hole 3201, and the weight-reducing hole 3203 is used to balance the counterweight block 3204, and the weight-reducing hole 3202 can reduce material consumption on the basis of maintaining the axis.

[0025] The difference between the first crankshaft 321 and the second crankshaft 322 is that: the first crankshaft 321 is provided with a pin hole 3205 penetrating to the main shaft hole 3201 at the counterweight block 3204, and the second crankshaft 322 is provided with a pin hole 3205 penetrating through the weight reduction hole 3203 and then penetrating to the main shaft hole 3201 on the opposite side of the counterweight block 3204, and a locking pin 34 is installed in each of the pin holes 3205. After the crankshaft piston structure 3 is installed, the bottom surface of the locking pin 34 abuts against the locking end surface 211 of the driving shaft 21, thereby realizing the relative fixed connection between the crankshaft and the piston connecting rod 33. By setting different positions of the pin holes 3205 on the first crankshaft 321 and the second crankshaft 322, the locking pin 34 can be located on the same side of the driving shaft 21 during the mating installation. Therefore, during production and processing, the driving shaft 21 only needs to mill out one locking end face 211, and there is no need to mill out the two opposite sides, which reduces the processing steps and improves the processing efficiency of the active motor 2.

[0026] The piston crankshaft structure is installed in cooperation with the piston connecting rod 33 through the first crankshaft 321 and the second crankshaft 322 respectively, so that the oppositely arranged piston connecting rods 33 are installed in a staggered manner. Therefore, when the active motor 2 drives the active shaft 21 to run, the piston movement in the multiple cylinder bodies 14 on the front and rear sides can realize the synchronous intake, compression and discharge of gas, which greatly improves the output pressure and flow of the multi-cylinder air compressor.

[0027] Embodiment 2: like Figure 5 As shown, in the second embodiment, the air compressor housing 1 of the multi-cylinder air compressor is installed in a centrally symmetrical manner with the active motor 2 as the center. By adjusting the relative positions of the first crankshaft 321, the second crankshaft 322 and the piston connecting rod 33 in the crankshaft-piston structure 3 on the active shaft 21, the piston movement of the multiple cylinder bodies 14 on the front and rear sides for synchronous gas intake, compression and discharge can also be achieved.

[0028] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0029] Although various terms are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. A symmetrical multi-cylinder air compressor, mainly comprising an air compressor housing (1), an active motor (2) and a crankshaft piston structure (3); It is characterized in that The air compressor housing (1) is a split structure, comprising a motor housing (11), a connecting bracket (12), a crankcase (13) and a cylinder block (14); the outer diameters of both ends of the motor housing (11) are reduced to form symmetrical housing sleeves (111), and the connecting bracket (12) and the crankcase (13) are sequentially installed and connected on both sides with the motor housing (11) as the center; The connecting bracket (12) is formed with a connecting sleeve (121) sleeved on the outside of the casing sleeve (111) on the side facing the motor housing (11), and a bracket partition layer (122) with four corners extending outward is formed at the end of the connecting sleeve (121) sleeved and connected, and the outer edges of the four corners of the bracket partition layer (122) are integrally extended to the side facing the crankcase (13) to form a cylinder bracket (123), and two cylinder columns (1231) are formed on each of the cylinder brackets (123), and a nearly circular shape is formed between the front and rear cylinder brackets (123). The support piston groove (1232) of the cylinder support (123) is connected to the cylinder body (14) through the cylinder column (1231) and the support piston groove (1232); the front and rear outer side walls of the middle section of the connecting sleeve (121) are both formed with C-shaped semi-open foot connection ears (124); the foot connection ears (124) cooperate with the quick-connect foot (4) to achieve quick-connect installation; the crankcase (13) is a hood-shaped structure as a whole, and the front and rear sides thereof are provided with case piston grooves (131) corresponding to the support piston groove (1232); The active motor (2) is coaxially mounted inside the motor housing (11), and active shafts (21) are extended from both ends of the active motor (2), and fastening end surfaces (211) are milled on both sides of the active shafts (21); The crankshaft piston structure (3) is sleeved on the driving shaft (21) of the driving motor (2) and installed inside the connecting bracket (12) and the crankcase (13). The structure includes a main shaft bearing (31), a first crankshaft (321), a pair of piston connecting rods (33) arranged in front and back opposite directions, and a second crankshaft (322). The piston connecting rod (33) has a piston bearing (331) installed in its big head ring. The first crankshaft (321) and the second crankshaft (322) are both two-section structures, the west end with a smaller outer diameter extends into the center of the piston bearing (331) for matching connection, the thick end with a larger outer diameter is protruded on one side to form a counterweight block (3204), and a main shaft hole (3201) deviating from the crankshaft axis is opened through the crankshaft near the counterweight block (3204). The difference between the first crankshaft (321) and the second crankshaft (322) is that the first crankshaft (321) has a main shaft hole (3201) that is offset from the crankshaft axis. ) is provided with a pin hole (3205) penetrating to the main shaft hole (3201), and the second crankshaft (322) is provided with a pin hole (3205) penetrating to the main shaft hole (3201) on the opposite side of the counterweight block (3204), and a locking pin (34) is installed in each of the pin holes (3205). After the crankshaft piston structure (3) is installed, the bottom surface of the locking pin (34) abuts against the locking end surface (211) of the driving shaft (21), thereby realizing relative fixed connection between the crankshaft and the piston connecting rod (33).

2. A symmetrical multi-cylinder air compressor according to claim 1, characterized in that: The center of the bracket partition layer (122) is coaxially provided with a central bearing hole (1221) with the driving shaft (21) of the driving motor (2), and a main shaft bearing (31) sleeved on the driving shaft (21) is mounted in the central bearing hole.

3. A symmetrical multi-cylinder air compressor according to claim 1, characterized in that: The four corners extending from the bracket partition layer (122) are each provided with a screw mounting hole (1222), and the connecting brackets (12) on both sides of the motor housing (11) are relatively fixed by connecting screws (125) passing through the screw mounting holes (1222) on both sides.

4. A symmetrical multi-cylinder air compressor according to claim 1, characterized in that: The cylinder bracket (123) is provided with bracket connection holes (1233) at arc-shaped transitional connection points on the upper and lower sides, and the crankcase (13) is provided with case connection holes (132) on the upper and lower sides corresponding to the bracket connection holes (1233). The connecting bracket (12) and the crankcase (13) are fixedly connected to each other by bolts penetrating the bracket connection holes (1233) and the case mounting holes.

5. A symmetrical multi-cylinder air compressor according to claim 1, characterized in that: A quick-connect convex ring (1241) is formed on the C-shaped inner wall of the base connecting ear (124); the quick-connect base (4) includes a base center column (41) and a positioning nut (42), a nut gasket (43) and an elastic clamping block (44) sleeved thereon, the positioning nut (42) and the nut gasket (43) forming a group, each of which is arranged at the upper and lower ends of the elastic clamping block (44) and at one end of the base center column (41) close to the installation plane when the air compressor is installed; the elastic clamping block (44) is made of elastic shock-absorbing material, and an annular quick-connect groove (441) is provided at the middle section, and the quick-connect groove (441) cooperates with the quick-connect convex ring (1241) to realize an adjustable quick-connect installation between the quick-connect base (4) and the base connecting ear (124).

6. A symmetrical multi-cylinder air compressor according to claim 1, characterized in that: The first crankshaft (321) and the second crankshaft (322) are both provided with a main shaft hole (3201), a material reduction hole (3202) and a weight reduction hole (3203) extending therethrough. The main shaft hole (3201), the weight reduction hole (3203) and the counterweight block (3204) are located on a straight line, and the material reduction hole (3202) is symmetrically distributed on both sides of the main shaft hole (3201) and the weight reduction hole (3203). The pin hole (3205) of the first crankshaft (321) extends from the counterweight block (3204) to the main shaft hole (3201), and the pin hole (3205) of the second crankshaft (322) extends from the opposite side of the counterweight block (3204) through the weight reduction hole (3203) and then to the main shaft hole (3201).

7. A symmetrical multi-cylinder air compressor according to claim 1, characterized in that: The air compressor housing (1) is centered on the driving motor (2), and by adjusting the relative positions of the first crankshaft (321), the second crankshaft (322) and the piston connecting rod (33) on the driving shaft (21) in the crankshaft-piston structure (3), axisymmetric installation or center-symmetric installation of the multi-cylinder air compressor can be achieved.

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