Double-piston assembly, two-stage compressor and vehicle

Abstract

The embodiment of the utility model discloses a double-piston assembly, a two-stage compressor and a vehicle. The double-piston assembly comprises a piston frame, a first piston, a second piston, a bush and a sliding block, an installation groove is formed in the piston frame, the first piston and the second piston are connected through the piston frame, the bush is installed in the installation groove, a sliding groove is formed in the bush, and the sliding groove is provided with a first guide face and a second guide face which are parallel to each other and face each other in the first direction. The sliding block is arranged in the sliding groove in a matched mode, can move in the sliding groove in the second direction orthogonal to the first direction and is guided by the first guiding face and the second guiding face. The double-piston assembly provided by the embodiment of the utility model is more compact in structure, low in manufacturing and maintenance cost and long in service life.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of compressor, specifically, a double piston assembly, two-stage compressor and vehicle. BACKGROUND

[0002] Compressor is widely used air compression device, usually also can be called air pump, can be used to supply compressed air to the pneumatic device of vehicle such as off-road vehicle, sport utility vehicle (SUV), passenger vehicle and commercial vehicle, for example air spring. In order to improve the compression efficiency, the related technology proposes two-stage compressor, two-stage compressor has two pistons rigidly connected with each other through a piston frame, the piston frame is connected with the driving shaft through the crank connecting rod mechanism, and the two pistons are radially opposite relative to the rotation axis of the driving shaft. Due to the large size of the connecting rod of the crank connecting rod mechanism, the space required for the movement of the crank connecting rod mechanism is large, which leads to the large volume of the compressor and the difficulty of miniaturization. The related technology also proposes a two-stage compressor, the piston frame is connected with the driving shaft through the sliding groove guide device, but this two-stage compressor has the problems of high manufacturing cost, short service life and large noise after a period of use. SUMMARY

[0003] The utility model aims at at least one of the technical problems in the related art to some extent.

[0004] Therefore, the embodiment of the utility model provides a double piston assembly with low manufacturing cost and long service life.

[0005] The embodiment of the utility model also provides a two-stage compressor with the double piston assembly of the above embodiment.

[0006] The embodiment of the utility model also provides a vehicle with the two-stage compressor of the above embodiment.

[0007] The double piston assembly of the embodiment of the utility model comprises a piston frame, a first piston, a second piston, a bushing and a sliding block, the piston frame has a mounting groove in it, the first piston and the second piston are connected with each other through the piston frame, the bushing is installed in the mounting groove, the bushing has a sliding groove in it, the sliding groove has a first guide surface and a second guide surface parallel to each other and facing each other in a first direction (A), the sliding block is fitted in the sliding groove, and the sliding block is movable in a second direction (B) orthogonal to the first direction in the sliding groove and guided by the first guide surface and the second guide surface.

[0008] The double-piston assembly is more compact in structure, and can reciprocate in a smaller space.

[0009] The two-stage compressor of the embodiment of the utility model includes cylinder, double-piston assembly and driving device, the cylinder has first compression chamber and second compression chamber, the double-piston assembly is the double-piston assembly in the above embodiment, the first piston is movably arranged in the cylinder and is used for compressing the gas in the first compression chamber, the second piston is movably arranged in the cylinder and is used for compressing the gas in the second compression chamber, the first compression chamber and the second compression chamber are communicated through the communication air channel that penetrates the piston frame, the first piston and the second piston, the driving device is connected with the sliding block and is used for driving the sliding block to slide in the sliding slot.

[0010] The vehicle of the embodiment of the utility model includes pneumatic device and the two-stage compressor in the above embodiment, the two-stage compressor is connected with the pneumatic device and is used for supplying compressed air to the pneumatic device. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is the explosion schematic view of the double-piston assembly of the first embodiment of the utility model.

[0012] Figure 2 It is the side view schematic view of the double-piston assembly of the first embodiment of the utility model.

[0013] Figure 3 It is the cross-sectional view schematic view of the double-piston assembly of the first embodiment of the utility model.

[0014] Figure 4 It is the explosion schematic view of the two-stage compressor of the embodiment of the utility model.

[0015] Figure 5 It is the cross-sectional view schematic view of the two-stage compressor of the embodiment of the utility model.

[0016] Figure 6 It is the cross-sectional view schematic view of the cylinder sleeve of the two-stage compressor of the embodiment of the utility model.

[0017] Figure 7 It is the partial explosion schematic view of the double-piston assembly of the second embodiment of the utility model.

[0018] Figure 8 is an exploded schematic view of the dual piston assembly of the second embodiment of the present utility model.

[0019] Figure 9 is a sectional view schematic view of the dual piston assembly of the second embodiment of the present utility model.

[0020] Figure 10 is an exploded schematic view of the dual piston assembly of the third embodiment of the present utility model.

[0021] Figure 11 is a sectional view schematic view of the dual piston assembly of the third embodiment of the present utility model.

[0022] Figure 12 is an exploded schematic view of the dual piston assembly of the fourth embodiment of the present utility model.

[0023] Figure 13 is a sectional view schematic view of the dual piston assembly of the fourth embodiment of the present utility model.

[0024] Figure 14 is a structure schematic view of the valve plate of the two-stage compressor of the embodiment of the present utility model.

[0025] Figure 15 is a sectional view schematic view of the valve plate of the two-stage compressor of the embodiment of the present utility model.

[0026] Figure 16 is a sectional view schematic view of another valve plate of the two-stage compressor of the embodiment of the present utility model.

[0027] Figure 17 is a local schematic view of the valve plate of the two-stage compressor of the embodiment of the present utility model in a closed state.

[0028] Figure 18 is a local schematic view of the valve plate of the two-stage compressor of the embodiment of the present utility model in an open state.

[0029] Figure 19 is an exploded schematic view of the two-stage compressor of another embodiment of the present utility model.

[0030] Figure 20 is a sectional view schematic view of the two-stage compressor of another embodiment of the present utility model.

[0031] Figure 21 is a sectional view schematic view of the planetary reduction assembly and motor of the two-stage compressor of another embodiment of the present utility model after assembly.

[0032] Figure 22 is an exploded schematic view of the planetary reduction assembly and motor of the two-stage compressor of another embodiment of the present utility model.

[0033] Figure 23Is the three-dimensional schematic view of the crankshaft of the two-stage compressor of another embodiment of the utility model.

[0034] Figure 24 Is the three-dimensional schematic view of the vehicle of the embodiment of the utility model.

[0035] Reference signs:

[0036] 100, vehicle; 10012, two-stage compressor; 1002, pneumatic device;

[0037] 1, cylinder; 1011, first cylinder cavity; 1012, second cylinder cavity; 1021, first compression chamber; 1022, second compression chamber; 11, cylinder body; 111, intake passage; 112, front bearing; 113, air inlet; 114, air outlet; 12, cylinder sleeve; 121, wear-resistant layer; 122, bevel; 13, cylinder cover; 15, exhaust valve;

[0038] 2, double-piston assembly; 201, communication air channel; 202, valve piece installation slot;

[0039] 21, piston frame;

[0040] 211, installation slot;

[0041] 221, first piston; 2211, first piston head; 22111, intake through hole; 2212, first piston ring; 2213, compression ring; 2214, first guide ring;

[0042] 222, second piston; 2221, second piston head; 2222, second piston ring; 2223, second guide ring;

[0043] 223, fixed part;

[0044] 224, flange;

[0045] 23, bushing; 231, sliding groove; 2311, first guide surface; 2312, second guide surface; 232, first bushing body; 2321, first recess; 2322, first elastic member; 233, second bushing body; 2331, second recess; 2332, second elastic member;

[0046] 24, sliding block; 241, first working surface; 2411, first accommodating slot; 2412, first rolling member; 242, second working surface; 2421, second accommodating slot; 2422, second rolling member; 243, sliding block hole; 244, clamping groove;

[0047] 25, bearing;

[0048] 26, bearing seat; 261, lug; 262, seat hole;

[0049] 3, planetary reduction assembly; 301, matching hole; 31, inner gear ring; 311, cylinder; 312, annular boss; 32, planet carrier; 321, assembly groove; 322, rear bearing; 33, sun gear; 34, planet gear; 35, planet gear shaft;

[0050] 4, motor; 401, matching part; 41, motor shaft; 42, motor shell; 43, motor rear end cover; 44, rotor; 45, stator; 46, rotor front bearing; 47, rotor rear bearing; 48, sealing ring;

[0051] 5, crankshaft; 51, main shaft part; 511, assembly hole; 52, eccentric shaft part; 53, balance block;

[0052] 7, dryer; 71, air outlet;

[0053] 8, valve plate; 81, plate body; 82, slot; 821, outer slot segment; 822, inner slot segment; 823, connecting slot segment; 83, sealing part; 84, mounting part; 85, swing arm; 86, first connecting part; 87, second connecting part; 801, first valve plate; 802, second valve plate;

[0054] 9, driving device. DETAILED DESCRIPTION

[0055] The embodiments of the present application will be described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0056] The double-piston assembly of the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0057] As shown in the drawings, the double-piston assembly 2 comprises a piston holder 21, a first piston 221, a second piston 222, a bushing 23 and a slider 24. Figures 1-24 The piston holder 21 can also be commonly referred to as a piston rod, and the first piston 221 and the second piston 222 are connected to each other through the piston holder 21, in other words, the piston holder 21 has a first end and a second end along its length direction, the first piston 221 is arranged at the first end of the piston holder 21, and the second piston 222 is arranged at the second end of the piston holder 21.

[0058] The piston holder 21 can also be commonly referred to as a piston rod, and the first piston 221 and the second piston 222 are connected to each other through the piston holder 21, in other words, the piston holder 21 has a first end and a second end along its length direction, the first piston 221 is arranged at the first end of the piston holder 21, and the second piston 222 is arranged at the second end of the piston holder 21.

[0059] The piston frame 21 has a mounting groove 211, for example, the middle cross section of the piston frame 21 is enlarged, and the mounting groove 211 is formed in the middle of the piston frame 21. The bushing 23 is mounted in the mounting groove 211. Preferably, the bushing 23 is detachably mounted in the mounting groove 211, for example, the bushing 23 can be press-fitted into the mounting groove 211 by a cold pressing or hot pressing process. The bushing 23 has a sliding groove 231, and the sliding groove 231 has a first guide surface 2311 and a second guide surface 2312, the first guide surface 2311 and the second guide surface 2312 face each other in the first direction A, and the first guide surface 2311 and the second guide surface 2312 are parallel to each other.

[0060] The sliding block 24 is fitted in the sliding groove 231, and the sliding block 24 is movable in the sliding groove 231 in the second direction B, wherein the second direction B is orthogonal to the first direction A, and the sliding block 24 is guided to slide in the sliding groove 231 by the first guide surface 2311 and the second guide surface 2312.

[0061] In some specific examples, the first direction A can be the length direction of the piston frame 21, and the second direction B can be the width direction of the piston frame 21.

[0062] In some specific examples, the sizes of the first piston 221 and the second piston 222 can be different, for example, the diameter of the first piston 221 is greater than the diameter of the second piston 222, the first piston 221 can be referred to as a low-pressure side piston, and the second piston 222 can be referred to as a high-pressure side piston, and the air compressed by the first piston 221 can be further compressed by the second piston 222.

[0063] The double-piston assembly 2 of the embodiment of the utility model, the sliding block 24 is driven to reciprocate in the sliding groove 231 by the driving device 9, so as to drive the first piston 221 and the second piston 222 to compress air.

[0064] Compared with the crank connecting rod mechanism in the related art, the double-piston assembly of the embodiment of the utility model adopts the sliding block and sliding groove structure, the structure is more compact, so as to reciprocate in a smaller space, which is beneficial to the miniaturization of the double-piston assembly. In addition, the double-piston assembly of the embodiment of the utility model, by installing the bushing in the piston frame, the sliding block slides in the sliding groove of the bushing, in the manufacturing, the whole piston frame does not need to be made of wear-resistant material, and the piston frame does not need to be wear-resistant treated, which reduces the cost, and when the bushing is worn, only the worn surface of the bushing needs to be repaired, for example, the first guide surface and the second guide surface are sprayed with a wear-resistant coating, or only the bushing needs to be replaced without replacing the whole piston frame, which reduces the manufacturing and maintenance cost and improves the service life of the piston frame.

[0065] In some examples, as shown in Figures 1-20 The first piston 221 and / or the second piston 222 are provided with the valve plate 8. Preferably, as shown in Figure 1As shown, the first piston 221 is provided with a first valve plate 801, and the second piston 222 is provided with a second valve plate 802, and the first valve plate 801 and the second valve plate 802 can be called intake valve plates, and here, the first valve plate 801 and the second valve plate 802 can be collectively called valve plates 8.

[0066] As shown in the figure, Figures 14-18 The valve plate 8 includes a plate body 81, and the plate body 81 is provided with a slot 82 penetrating through the plate body 81 along the thickness direction of the plate body 81. The slot 82 divides the plate body 81 into a sealing portion 83, a mounting portion 84 and a plurality of swing arms 85. The sealing portion 83 and the mounting portion 84 are concentric with each other, that is, the center of the sealing portion 83 coincides with the center of the mounting portion 84, and the mounting portion 84 is arranged around the sealing portion 83.

[0067] The swing arm 85 is an elastic arm, and the width of the swing arm 85 is generally constant in the length direction of the swing arm 85, and the first end of the swing arm 85 is connected with the sealing portion 83, and the second end of the swing arm 85 is connected with the mounting portion 84.

[0068] When the number of swing arms 85 is even, the plurality of swing arms 85 are arranged in pairs, that is, the plurality of swing arms 85 are divided into at least one pair, and the two swing arms 85 in the same pair are centrally symmetric to each other with respect to the center of the sealing portion 83, that is, one swing arm 85 is rotated by 180 degrees to coincide with the other swing arm 85. When the number of swing arms 85 is odd, the plurality of swing arms 85 are uniformly arranged around the center of the sealing portion 83 along the circumferential direction of the sealing portion 83, for example, the number of swing arms 85 is N, N is odd, and in the adjacent two swing arms 85, one swing arm 85 is rotated by 360 / N degrees around the center of the sealing portion 83 to coincide with the other swing arm 85.

[0069] In the embodiment of the utility model, the swing arm 85 is centrally symmetric or uniformly arranged along the circumferential direction of the sealing portion 83, which improves the stress uniformity of the sealing portion 83 and improves the uniformity of the valve plate 8 in opening and closing the valve port.

[0070] Optionally, the thickness T of the plate body 81 can be greater than or equal to 0.1 millimeter and less than or equal to 0.5 millimeter, for example, 0.1 millimeter, 0.2 millimeter, 0.3 millimeter, 0.4 millimeter, 0.5 millimeter.

[0071] The valve plate 8 can be a metal sheet, for example, a stainless steel sheet or an alloy sheet. Alternatively, the valve plate 8 can also be made of a non-metal sheet, for example, a resin sheet with sufficient flexibility and strength to meet the design requirements.

[0072] The width of the slot 82 should ensure that the swing arm 85, the sealing portion 83 and the mounting portion 84 do not interfere with each other during use of the valve disc 8. Preferably, the width H of the swing arm 85 can be greater than or equal to 1.3 mm and less than or equal to 5 mm, and the width of the slot 82 can be greater than or equal to 1 mm and less than or equal to 4 mm. If the width of the swing arm 85 is too narrow, the valve disc 8 will deform after a period of use, and if the width of the swing arm 85 is too wide, it will affect the sensitivity of the sealing portion 83 to open and close the valve port. The slot 82 can be formed by stamping a metal sheet. In other words, the valve disc 8 is integrally formed by stamping a metal sheet.

[0073] Compared with the valve disc in the related art, in the embodiments of the present application, the opening height of the valve disc is uniform, the flow area of the valve port is large at the same opening height, the airflow flows smoothly, the air resistance is small, and the response speed of the valve disc is high. In addition, the swing arms are centrally symmetric or uniformly arranged in the circumferential direction, so that the sealing portions are uniformly stressed, which not only improves the sensitivity of the valve disc to open and close, but also reduces the fatigue of the valve disc after a period of use, thereby prolonging the service life of the valve disc.

[0074] In addition, compared with the width variation of the swing arm of the valve disc in the related art, in the embodiments of the present application, the width of the swing arm is generally uniform in the length direction, which further improves the uniformity of the stress of the sealing portion and the uniformity of the opening and closing of the valve port, thereby further improving the response speed and sensitivity of the valve disc.

[0075] In some specific examples, as shown in Figure 14 and Figure 15 The sheet body 81 can be a stainless steel sheet with a thickness of 0.1 mm. The sealing portion 83 is circular, and the mounting portion 84 is annular and surrounds the sealing portion 83. The swing arm 85 is in the shape of a circular arc, the width H of the swing arm 85 can be 5 mm, and the swing arm 85 is two and centrally symmetric with respect to each other about the center of the sealing portion 83. The swing arm 85 is connected to the sealing portion 83 through the first connecting portion 86 and connected to the mounting portion 84 through the second connecting portion 87, so that the width of the swing arm 85 can be more uniform, further improving the uniformity of the valve disc 8 to open and close the valve port.

[0076] The slot 82 is two, each slot 82 includes an outer slot segment 821, an inner slot segment 822 and a connecting slot segment 823 connected between the outer slot segment 821 and the inner slot segment 822. As shown in Figure 15 One swing arm 85 is located between the outer slot segment 821 of one slot 82 and the inner slot segment 822 of another slot 82, and the other swing arm 85 is located between the inner slot segment 822 of the one slot 82 and the outer slot segment 821 of the other slot 82.

[0077] The outer slot section 821 and the inner slot section 822 are both circular arc-shaped, and the connecting slot section 823 is composed of multiple circular arc sections with different protruding directions and smoothly connected to each other. The central angles θ of the inner slot section 822 and the outer slot section 821 are equal, and preferably, the central angle θ is greater than or equal to 120 degrees and less than or equal to 150 degrees. In the embodiment shown in Figure 14 and Figure 15 the central angle θ is 120 degrees.

[0078] In other specific examples, as shown in Figure 16 the sheet body 81 can be a stainless steel sheet with a thickness of 0.3 mm. The sealing portion 83 is circular, the mounting portion 84 is annular and surrounds the sealing portion 83. The swing arms 85 are circular arc-shaped, the width H of the swing arms 85 can be 4 mm, there are three swing arms 85 and they are uniformly arranged along the circumference of the sealing portion 83 around the center of the sealing portion 83, the swing arms 85 are connected to the sealing portion 83 through the first connecting portions 86 and connected to the mounting portion 84 through the second connecting portions 87.

[0079] The slots 82 are three, each slot 82 includes an outer slot section 821, an inner slot section 822 and a connecting slot section 823 connected between the outer slot section 821 and the inner slot section 822. As shown in Figure 16 each swing arm 85 is located between the outer slot section 821 of one slot 82 and the inner slot section 822 of the adjacent other slot 82. The outer slot section 821 and the inner slot section 822 are both circular arc-shaped, and preferably, the central angle θ is greater than or equal to 60 degrees and less than or equal to 90 degrees.

[0080] The installation and operation of the valve sheet will be described below taking the valve sheet (second valve sheet) provided on the second piston as an example.

[0081] As shown in Figure 17 and Figure 18 the second piston 222 is provided with a valve sheet mounting groove 202, the second valve sheet 802 is mounted in the valve sheet mounting groove 202, the mounting portion 84 is fixed by the fixing portion 223 on the second piston 222, and the sealing portion 83 is opposite to the port (also referred to as valve port) of the communication air passage 201 penetrating through the second piston 222.

[0082] Preferably, a flange 224 surrounding the valve port is provided on the surface of the second piston 222, and the upper surface of the flange 224 can be referred to as a sealing surface. As shown in Figure 17 when the air pressure in the communication air passage 201 is less than the sum of the elastic force of the swing arm 85 and the air pressure in the compression chamber (second compression chamber 1022), the valve sheet 8 is pressed on the upper surface of the flange 224 to close the valve port. As shown in Figure 18As shown, when the air pressure in the communication air passage 201 is greater than the sum of the elastic force of the swing arm 85 and the air pressure in the second compression chamber 1022, the gas in the communication air passage 201 pushes the sealing part 83 to translate upward away from the sealing surface, thereby opening the valve port, and the air flow F in the communication air passage 201 enters the second compression chamber 1022 through the slot 82 of the valve plate 8.

[0083] The double-piston assembly of the first embodiment of the present application will be described below in conjunction with the drawings.

[0084] As shown in the drawings, the double-piston assembly 2 comprises a piston frame 21, a first piston 221, a second piston 222, a bushing 23, a sliding block 24 and a bearing 25. Figures 1-3 The piston frame 21 has a first end and a second end in the length direction thereof, the first piston 221 is arranged at the first end of the piston frame 21, and the second piston 222 is arranged at the second end of the piston frame 21.

[0085] The first piston 221 comprises a first piston head 2211, a first piston ring 2212, a compression ring 2213 and a first guide ring 2214. The first piston head 2211 has a first piston ring groove thereon, and the first piston ring 2212 is fitted in the first piston ring groove. The compression ring 2213 is sleeved on the first piston head 2211, the compression ring 2213 has a first guide ring groove thereon, and the first guide ring 2214 is fitted in the first guide ring groove.

[0086] The first piston head 2211 is provided with an air inlet through hole 22111, and external air enters the first compression chamber 1021 through the air inlet through hole 22111. A first valve plate 801 is arranged on the surface of the first piston head 2211, and the first valve plate 801 can be the valve plate 8 of the above-mentioned embodiment, which is used to open and close the port (valve port) of the air inlet through hole 22111.

[0087] As shown in the drawings, in this embodiment, the first valve plate 801 is two, and correspondingly, the air inlet through hole 22111 is two to meet the air intake requirement. Figure 1

[0088] The second piston 222 comprises a second piston head 2221, a second piston ring 2222 and a second guide ring 2223. The second piston head 2221 has a second piston ring groove and a second guide ring groove thereon, the second piston ring 2222 is fitted in the second piston ring groove, and the second guide ring 2223 is fitted in the second guide ring groove.

[0089] As shown in the drawings, the double-piston assembly 2 comprises a communication air passage 201 penetrating through the first piston 221, the piston frame 21 and the second piston 222, a second valve plate 802 is arranged on the surface of the second piston head 2221, which is used to open and close the port (valve port) of the communication air passage 201, and the second valve plate 802 can be the valve plate 8 of the above-mentioned embodiment. Figure 3 ​​

[0090] The middle part of the piston frame 21 has a generally rectangular mounting groove 211. The bushing 23 is in the form of a rectangular ring, which is detachably mounted in the mounting groove 211, for example, the bushing 23 is press-fitted into the mounting groove 211 through a hot pressing or cold pressing process. The inner cavity of the bushing 23 constitutes a sliding groove 231, which is generally rectangular and has a first guide surface 2311 and a second guide surface 2312 facing each other in the first direction A, and a wear-resistant coating is provided on the first guide surface 2311 and the second guide surface 2312 to improve the wear resistance of the bushing 23. The wear-resistant coating can be formed on the first guide surface 2311 and the second guide surface 2312 by spraying or electroplating process.

[0091] The sliding block 24 is slidably fitted in the sliding groove 231 along a second direction B orthogonal to the first direction A. Specifically, the sliding block 24 has a first working surface 241 and a second working surface 242 facing away from each other along the first direction A, the first working surface 241 is in sliding contact with the first guide surface 2311, and the second working surface 242 is in sliding contact with the second guide surface 2312.

[0092] The wear coefficient of the sliding block 24 is greater than the wear coefficient of the bushing 23, in other words, the bushing 23 is more wear-resistant than the sliding block 24, so as to prolong the service life of the bushing 23, and the sliding block 24 is easier to replace than the bushing 23, which can improve the maintenance efficiency.

[0093] For example, the bushing 23 can be made of metal, and the sliding block 24 can be made of a low-friction coefficient composite material, such as a polytetrafluoroethylene-based composite material or a polyether ether ketone-based composite material, or the surface of the sliding block 24 is provided with a composite material layer with a low friction coefficient. For example, the composite material or the composite material layer can be formed by adding graphite, copper powder, carbon fiber or glass fiber to the composite polytetrafluoroethylene material.

[0094] The sliding block 24 has a sliding block hole 243 in it, and the bearing 25 is fitted in the sliding block hole 243. The bearing 25 can be connected to a driving shaft for driving the double-piston assembly 2, so that the sliding block 24 is driven to reciprocally slide in the sliding groove 231, thereby driving the first piston 221 and the second piston 222 to move.

[0095] The second embodiment of the double-piston assembly of the utility model will be described below in conjunction with the drawings.

[0096] As shown in Figures 7-9 The double-piston assembly 2 includes a piston frame 21, a first piston 221, a second piston 222, a bushing 23, a sliding block 24, a bearing seat 26 and a bearing 25.

[0097] The slider 24 has a slider hole 243 in which the bearing seat 26 is installed. An anti-rotation structure is provided between the slider 24 and the bearing seat 26 to prevent the bearing seat 26 from rotating relative to the slider 24. In one example, the anti-rotation structure includes a clamping groove 244 provided on an end face of the slider 24 and a lug 261 provided on the bearing seat 26 and fitted in the clamping groove 244, so that the bearing seat 26 is prevented from rotating relative to the slider 24 and the bearing seat 26 is improved in firmness. The bearing seat 26 has a seat hole 262 in which the bearing 25 is installed. In an alternative example, the slider hole 243 is non-circular and the bearing seat 26 has a non-circular cross-sectional profile that matches the slider hole 243, so that the bearing seat 26 is prevented from rotating relative to the slider 24 when installed in the slider hole 243. In this example, the non-circular slider hole and the non-circular cross-sectional profile of the bearing seat constitute the anti-rotation structure.

[0098] The bearing seat can be a metal bearing seat, and the slider can be made of a resin composite material, such as a polytetrafluoroethylene-based composite material or a polyether ether ketone-based composite material. Since the bearing seat is a metal bearing seat, the bearing seat is less likely to be expanded by heat compared to the slider during operation of the dual-piston assembly, so that the bearing is less likely to loosen in the bearing seat, the firmness of the bearing is improved, and noise is reduced.

[0099] The dual-piston assembly of the second embodiment of the present application can be similar to the dual-piston assembly of the above-described embodiments in other aspects, and will not be described here again.

[0100] A third embodiment of a dual-piston assembly of the present application will be described below with reference to the accompanying drawings.

[0101] As shown in Figure 10 and Figure 11 , the dual-piston assembly 2 includes a piston frame 21, a first piston 221, a second piston 222, a bushing 23, a slider 24, a bearing seat 26, and a bearing 25.

[0102] The bushing 23 includes a first bushing body 232 and a second bushing body 233, and the first bushing body 232 and the second bushing body 233 are U-shaped and are butted together along a first direction A to define a sliding groove 231 in the bushing 23. Preferably, the first bushing body 232 and the second bushing body 233 are symmetrical to each other. By dividing the bushing 23 into the first bushing body 232 and the second bushing body 233, the processing of the bushing 23 is simplified, and the first bushing body 232 and the second bushing body 233 can be replaced separately, thereby reducing manufacturing and maintenance costs.

[0103] The first bushing body 232 has a first outer surface provided with a first groove 2321. A first elastic member 2322 is arranged in the first groove 2321 and abuts between the mounting groove 211 and the first bushing body 232. The second bushing body 233 has a second outer surface provided with a second groove 2331. A second elastic member 2332 is arranged in the second groove 2331 and abuts between the mounting groove 211 and the second bushing body 233. The first bushing body 232 and the second bushing body 233 are pressed towards each other by the first elastic member 2322 and the second elastic member 2332. For example, the first elastic member 2322 and the second elastic member 2332 are corrugated plates or arc-shaped plates.

[0104] By the first elastic member and the second elastic member, the first bushing body and the second bushing body can be reliably butted, the first guide surface of the first bushing body reliably contacts the first working surface of the sliding block, and the second guide surface of the second bushing body reliably contacts the second working surface of the sliding block, so as to reduce impact noise when the sliding block reverses.

[0105] The other aspects of the double-piston assembly of the third embodiment of the utility model can be similar to the double-piston assembly of the above-mentioned embodiments, which will not be described here again.

[0106] The double-piston assembly of the fourth embodiment of the utility model will be described below in combination with the drawings.

[0107] As shown in Figure 12 and Figure 13 The double-piston assembly 2 comprises a piston frame 21, a first piston 221, a second piston 222, a bushing 23, a sliding block 24 and a bearing 25.

[0108] The sliding groove 231 has a first guide surface 2311 and a second guide surface 2312. The sliding block 24 has a first working surface 241 and a second working surface 242. A plurality of first rolling members 2412 are arranged between the first working surface 241 and the first guide surface 2311, and a plurality of second rolling members 2422 are arranged between the second working surface 242 and the second guide surface 2312. For example, the first rolling members 2412 and the second rolling members 2422 are cylindrical bodies. The first working surface 241 is provided with a first accommodating groove 2411, and the first rolling members 2412 are arranged in the first accommodating groove 2411. The second working surface 242 is provided with a second accommodating groove 2421, and the second rolling members 2422 are arranged in the second accommodating groove 2421. It can be understood that a part of the first rolling members 2412 is exposed from the first accommodating groove 2411 to contact the first guide surface 2311 of the bushing 23, and a part of the second rolling members 2422 is exposed from the second accommodating groove 2421 to contact the second guide surface 2312 of the bushing 23.

[0109] By setting the first rolling element 2412 and the second rolling element 2422, when the slider 24 moves within the groove 231, the rolling friction between the slider 24 and the bushing 23 reduces the wear between the slider 24 and the bushing 23, and also lowers the machining accuracy requirements of the bushing 23 and the slider 24, thus reducing manufacturing costs. The surfaces of the first guide surface 2311, the second guide surface 2312, the groove surfaces of the first receiving groove 2411 and the second receiving groove 2421, as well as the surfaces of the first rolling element 2412 and the second rolling element 2422 can be hardened surfaces that have undergone finishing, with a surface hardness ≥50HRC and a surface finish ≤Ra0.8.

[0110] Other aspects of the dual-piston assembly of the fourth embodiment of this utility model are similar to those of the dual-piston assemblies of the above embodiments, and will not be described again here.

[0111] The following describes the two-stage compressor of an embodiment of the present invention with reference to the accompanying drawings.

[0112] like Figures 1-24 As shown, the two-stage compressor 10012 of this utility model embodiment includes a cylinder 1, a double piston assembly 2, and a drive device 9.

[0113] Cylinder 1 includes a cylinder body 11 and a cylinder head 13. The cylinder head 13 is mounted on the cylinder body 11, for example, by means of bolts that are detachably connected to the cylinder body 11. The cylinder body 11 has a first cylinder chamber 1011 and a second cylinder chamber 1012. The cylinder body 11 has an air inlet 113 and an air intake passage 111 communicating with the air inlet 113.

[0114] The dual-piston assembly 2 can be the dual-piston assembly 2 in the above embodiments. The first piston 221 is movably fitted within the first cylinder chamber 1011 and defines a first compression chamber 1021 within the first cylinder chamber 1011. The second piston 222 is movably fitted within the second cylinder chamber 1012 and defines a second compression chamber 1022 within the second cylinder chamber 1012. The first compression chamber 1021 and the second compression chamber 1022 are connected by a connecting passage 201 that passes through the piston holder 21, the first piston 221, and the second piston 222.

[0115] The intake passage 111 inside the cylinder block 11 communicates with the first compression chamber 1021 through the intake port 22111 inside the first piston head 2211, so that external gas can enter the first compression chamber 1021 from the intake port 113 through the intake passage 111 and the intake port 22111. The gas compressed in the first compression chamber 1021 enters the second compression chamber 1022 through the connecting passage 201 for further compression. The first compression chamber 1021 can be referred to as the primary or low-pressure compression chamber, and the second compression chamber 1022 can be referred to as the secondary or high-pressure compression chamber.

[0116] The driving device 9 comprises the motor 4 and the crankshaft 5. The motor 4 has a motor shaft 41, and the crankshaft 5 comprises a main shaft part 51 and an eccentric shaft part 52. A first end of the eccentric shaft part 52 is pivotally connected with the slider 24, and a second end of the eccentric shaft part 52 is connected with the main shaft part 51. The main shaft part 51 is coaxially connected with the motor shaft 41, and a central axis of the eccentric shaft part 52 is eccentric to a central axis of the motor shaft 41. The motor 4 drives the slider 24 to slide in the sliding groove 231 through the crankshaft 5, so as to drive the first piston 221 to reciprocate in the first compression chamber 1021 through the piston frame 21 and drive the second piston 222 to reciprocate in the second compression chamber 1022.

[0117] Compared with the compressor adopting a crank connecting rod in the related art, the two-stage compressor of the embodiment of the utility model adopts the structure of the slider and the sliding groove cooperation, the size of the piston frame is reduced, the length of the communication air passage is reduced, the clearance volume of the low-pressure cavity is reduced, the volumetric efficiency of the two-stage compressor is improved, the structure of the two-stage compressor is more compact, and the two-stage compressor is beneficial to miniaturization. Moreover, the bushing in the piston frame is convenient to maintain and replace after wearing, and the cost is low.

[0118] The two-stage compressor of one embodiment of the utility model will be described below in combination with the drawings.

[0119] As shown in the drawings, Figures 4-6 The two-stage compressor 10012 comprises a cylinder 1, a double-piston assembly 2, a motor 4, a crankshaft 5 and a dryer 7.

[0120] The cylinder 1 comprises a cylinder body 11, a cylinder cover 13 and an exhaust valve 15. The cylinder cover 13 is installed at the lower end of the cylinder body 11 and is detachably connected with the cylinder body 11, for example, through bolts.

[0121] The double-piston assembly 2 can be the double-piston assembly 2 of the above-mentioned embodiment. The cylinder body 11 has a first cylinder cavity 1011 and a second cylinder cavity 1012. The first piston 221 of the double-piston assembly 2 is movably fitted in the first cylinder cavity 1011 and defines a first compression chamber 1021 in the first cylinder cavity 1011, and the second piston 222 is movably fitted in the second cylinder cavity 1012 and defines a second compression chamber 1022 in the second cylinder cavity 1012, and the first compression chamber 1021 and the second compression chamber 1022 are communicated through a communication air passage 201 penetrating through the first piston 221, the piston frame 21 and the second piston 222.

[0122] The first piston 221 has an air inlet hole 22111 communicating with the first compression chamber 1021, the second compression chamber 1022 has an exhaust port 114, the exhaust valve 15 is arranged at the exhaust port 114, and the dryer 7 is connected with the cylinder body 11, so that the compressed air discharged from the second compression chamber 1022 through the exhaust port 114 enters the dryer 7 to be dried, and the dried compressed air is discharged from the compressed air outlet (air outlet 71) of the dryer 7.

[0123] The cylinder 11 has an air inlet 113, an air passage 111 in the cylinder 11 is communicated with the air inlet 113 and an air through hole 22111, and the first valve plate 801 is arranged at a port of the air through hole 22111 communicated with the first compression chamber 1021. The second valve plate 802 is arranged at a port of the communication passage 201 communicated with the second compression chamber 1022.

[0124] The upper part and the lower part of the cylinder 11 are respectively provided with the cylinder sleeve 12, in other words, the inner cavity of the cylinder sleeve 12 of the lower part constitutes the first cylinder cavity 1011, and the inner cavity of the cylinder sleeve 12 of the upper part constitutes the second cylinder cavity 1012. The cylinder 11 can be cast, and the cylinder sleeve 12 can be machined by using a pipe material, so that the wear-resistant treatment process of the cylinder sleeve 12 is simple, the quality is stable, the machining precision is easy to ensure, the cylinder 11 does not need to be subjected to wear-resistant treatment, and the cost is reduced.

[0125] The inner wall surface of the cylinder sleeve 12 can be a hard surface subjected to finishing machining, the microhardness is greater than or equal to 350HV, and the surface roughness is less than or equal to Ra0.8. The material of the cylinder sleeve 12 can be aluminum alloy, carbon steel, stainless steel or the like, and the surface treatment mode can be hard oxidation, hard chromium plating, plasma spraying or the like hard plating layer or coating (wear-resistant layer 121). Preferably, the inner wall of one end of the cylinder sleeve 12 has a bevel 122, so as to reduce the probability of damage of the piston ring and the guide ring during the introduction of the first piston 221 and the second piston 222 in the assembly process.

[0126] The crankshaft 5 comprises a main shaft part 51 and an eccentric shaft part 52. The first end of the eccentric shaft part 52 is pivotally connected with the sliding block 24 of the double-piston assembly 2, and the second end of the eccentric shaft part 52 is connected with the main shaft part 51. The main shaft part 51 is coaxially connected with the motor shaft 41 of the motor 4, and the central axis of the eccentric shaft part 52 is eccentric relative to the central axis of the motor shaft 41. The motor 4 drives the sliding block 24 to slide in the sliding groove 231 through the crankshaft 5, so as to drive the first piston 221 to reciprocate in the first compression chamber 1021 and drive the second piston 222 to reciprocate in the second compression chamber 1022 through the piston frame 21.

[0127] The operation of the two-stage compressor in the embodiment of the utility model is briefly described below.

[0128] Motor 4 drives slider 24 to slide within slide groove 231 via crankshaft 5, causing double piston assembly 2 to move upward. First valve 801 opens and second valve 802 closes. External air F enters first compression chamber 1021 through intake port 113, intake channel 111, and intake through-hole 22111 in first piston 221. When double piston assembly 2 reaches top dead center and begins downward movement, air is compressed in first compression chamber 1021. First valve 801 closes and second valve 802 opens, allowing gas in first compression chamber 1021 to enter second compression chamber 1022 through connecting air passage 201. When double piston assembly 2 reaches bottom dead center and begins upward movement again, air is compressed again in second compression chamber 1022. Then, exhaust valve 15 opens, and compressed gas in second compression chamber 1022 is discharged into dryer 7 for drying. The dried gas is discharged from outlet 71, for example, supplied to a compressed gas user device. This cycle repeats continuously.

[0129] The following describes another embodiment of the two-stage compressor of this utility model with reference to the accompanying drawings.

[0130] like Figures 19-23 As shown, the secondary compressor 10012 includes a cylinder 1, a double piston assembly 2, and a drive unit 9.

[0131] The cylinder block 11 has a first cylinder chamber 1011 and a second cylinder chamber 1012. The dual-piston assembly 2 can be the dual-piston assembly 2 of the above embodiment. The first piston 221 of the dual-piston assembly 2 is movably fitted in the first cylinder chamber 1011 and defines a first compression chamber 1021 in the first cylinder chamber 1011, and the second piston 222 is movably fitted in the second cylinder chamber 1012 and defines a second compression chamber 1022 in the second cylinder chamber 1012. The first compression chamber 1021 and the second compression chamber 1022 are connected by a connecting passage 201.

[0132] like Figures 19-23 As shown, the drive unit 9 includes a motor 4, a crankshaft 5, and a planetary reduction gear assembly 3. The motor 4 has a motor shaft 41, which is rotatably connected to the slider 24 of the double piston assembly 2 via the planetary reduction gear assembly 3 and the crankshaft 5. The planetary reduction gear assembly 3 has a large reduction ratio, so the motor 4 can be a high-speed motor, and requires less space, reducing the overall size and weight of the secondary compressor 10012.

[0133] For example, motor 4 can be a DC high-speed motor, and the speed of motor 4 can be greater than 4000 rpm. Preferably, the speed of motor 4 is greater than 8000 rpm. High-speed motors have small size, high speed, low torque, low moment of inertia, and fast start-stop response.

[0134] The embodiment of the utility model discloses, through adopting the combination of high -speed motor and planetary reduction assembly, make two -stage compressor can respond to load change quickly, guarantee the stability and accuracy of this response.

[0135] Compared with the ordinary speed reducer, the transmission efficiency of the planetary reduction assembly is high, which can not only reduce the power consumption required by the motor, thereby reducing the energy consumption of the two-stage compressor, but also improve the working efficiency of the two-stage compressor, and is especially suitable for vehicle compressor.

[0136] As shown in Figure 21 and Figure 22 , the motor 4 includes a motor shaft 41, a motor shell 42, a motor rear end cover 43, a rotor 44 and a stator 45. The rear end of the motor shell 42 has an opening, and the other end of the motor shell 42 is provided with a hole for the motor shaft 41 to pass through, and a rotor front bearing 46 is installed in the hole. The motor rear end cover 43 is detachably installed at the opening of the motor shell 42 by bolts, and the motor rear end cover 43 is provided with a groove, and the groove is provided with a rotor rear bearing 47. The motor shaft 41 is connected with the rotor 44, the part of the motor shaft 41 passing through the motor shell 42 is matched with the rotor front bearing 46, and the end of the motor shaft 41 located in the motor shell 42 is matched with the rotor rear bearing 47.

[0137] As shown in Figure 21 and Figure 22 , the planetary reduction assembly 3 includes an inner ring gear 31, a planet carrier 32, a sun gear 33 and a plurality of planetary gears 34. The planetary gears 34 are rotatably installed on the planet carrier 32 through planetary gear shafts 35, the sun gear 33 is installed on the motor shaft 41 of the motor 4, the inner ring gear 31 is connected with the motor shell 42 of the motor 4, the planetary gears 34 are respectively meshed with the sun gear 33 and the inner ring gear 31, and the crankshaft 5 is connected with the planet carrier 32.

[0138] The inner ring gear 31 is configured as a fixed gear of the planetary reduction assembly 3, and the inner ring gear 31 includes a cylinder body 311 and an annular boss 312, the annular boss 312 is arranged on the inner circumferential wall of the cylinder body 311, and an inner tooth is formed on the inner circumferential wall surface of the annular boss 312. The annular boss 312 defines a matching hole 301 in the cylinder body 311, the matching hole 301 is located at one end of the cylinder body 311 close to the motor 4, the end of the motor shell 42 is provided with a matching part 401 with reduced diameter, the matching part 401 is matched in the matching hole 301, one end of the cylinder body 311 is butted with one end of the motor shell 42, and the outer circumferential surface of the cylinder body 311 is flush with the outer circumferential surface of the motor shell 42.

[0139] The tight fit between the mating hole 301 and the mating part 401 reduces the distance between the planetary reduction gear assembly 3 and the motor 4, improving structural compactness, reducing volume and space occupation, thereby further reducing the volume of the secondary compressor 10012. Furthermore, the outer circumferential surface of the cylinder 311 is flush with the outer circumferential surface of the motor housing 42, improving the overall visual effect. Additionally, a sealing ring 48 or other sealing elements can be provided between the mating hole 301 and the mating part 401 to improve the sealing performance between the planetary reduction gear assembly 3 and the motor 4.

[0140] like Figure 22 As shown, the end face of the planetary carrier 32 furthest from the crankshaft 5 ( Figure 22 The right end face of the motor shaft 41 is provided with an assembly groove 321, and a rear bearing 322 is installed in the assembly groove 321. One end of the motor shaft 41 that extends out of the motor housing 42 is engaged with the rear bearing 322.

[0141] The motor shaft 41 drives the sun gear 33 to rotate around the central axis X1. The central axis X1 is the central axis of the motor shaft 41, the sun gear 33 and the planet carrier 32. The planet gear 34 revolves around the central axis X1 and rotates around the central axis of the planet gear shaft 35, thereby causing the planet carrier 32 to rotate around the central axis X1.

[0142] Preferably, the teeth of the internal gear ring 31 and the planetary gear 34 are helical teeth, which can reduce speed and increase torque, and reduce noise.

[0143] like Figures 21-23 As shown, the crankshaft 5 includes a main shaft portion 51 and an eccentric shaft portion 52. One end of the main shaft portion 51 is connected to the planetary carrier 32. The central axis of the main shaft portion 51 is coaxial with the central axis X1 of the planetary carrier 32, the internal gear ring 31, and the motor shaft 41, which will be referred to as the central axis X1 in the following description. The cylinder block 11 is provided with a front bearing 112, and the main shaft portion 51 mates with the front bearing 112.

[0144] Preferably, the main shaft 51 and the planetary carrier 32 can be integrally formed, thereby improving the overall strength and durability of the crankshaft 5, reducing the workload of crankshaft 5 assembly and maintenance, improving structural compactness, reducing volume and space occupied, and further reducing the volume of the secondary compressor 10012.

[0145] The main spindle 51 is provided with a mounting hole 511. One end of the eccentric shaft 52 is fitted into the mounting hole 511, and the other end of the eccentric shaft 52 extends out of the mounting hole 511. The central axis X2 of the eccentric shaft 52 is eccentric relative to the central axis X1 of the main spindle 51. The other end of the eccentric shaft 52 is fitted with a bearing 25 in the piston holder 21.

[0146] Since the dual piston assembly 2 and the eccentric shaft portion 52 are eccentrically arranged relative to the main shaft portion 51, the crankshaft 5 will generate unbalanced forces when rotating. Therefore, the main shaft portion 51 is provided with a balance block 53 to reduce or eliminate the vibration caused by the imbalance of the crankshaft 5, improve the stability and reliability of the crankshaft 5 operation, and reduce the noise generated by the vibration of the crankshaft 5.

[0147] The vehicle of this utility model embodiment is described below with reference to the accompanying drawings.

[0148] like Figure 24 As shown, the vehicle 100 of this embodiment includes a pneumatic device 1002 and a secondary compressor 10012. The secondary compressor 10012 can be the secondary compressor 10012 described in the above embodiment. The secondary compressor 10012 is connected to the pneumatic device 1002 and is used to supply compressed air to the pneumatic device 1002. For example, the pneumatic device 1002 can be an air spring of the air suspension system of the vehicle 100.

[0149] The vehicle of this utility model has a compact, small, lightweight, and highly adaptable two-stage compressor, which effectively solves the problems of large size and slow start-up response of automotive compressors in related technologies. Thus, the two-stage compressor of this utility model can provide a more efficient, compact, and reliable air supply solution for the vehicle's air suspension system.

[0150] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0151] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0152] In the utility model, unless another definite provision and limitation, the terms "mount", "link", "connect", "fix" and so on should do broad sense understanding, for example, can be fixed connection, also can be detachable connection, or be integrated;Can be mechanical connection, also can be electric connection or each other can communicate;Can be direct connection, also can indirectly connect through intermediate medium, can be two element internal communication or two element mutual action relation, unless another definite limitation.For ordinary skilled person in the art, can understand the specific meaning of above terms in the utility model according to specific circumstances.

[0153] In the utility model, unless another definite provision and limitation, first feature is "on" or "under" second feature can be that first and second features directly contact, or first and second features indirectly contact through intermediate medium.Moreover, first feature "over", "above" and "on" second feature can be that first feature is directly above or obliquely above second feature, or just indicates that the horizontal height of first feature is higher than that of second feature.First feature "under", "below" and "under" second feature can be that first feature is directly below or obliquely below second feature, or just indicates that the horizontal height of first feature is less than that of second feature.

[0154] In the utility model, the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model.In this specification, the illustrative representations of the above terms do not necessarily refer to the same embodiment or example.Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0155] Although the embodiments of the utility model have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the utility model, and those skilled in the art can change, modify, replace and modify the above embodiments within the scope of the utility model.

Claims

1. A dual-piston assembly, characterized in that, include: A piston holder, wherein the piston holder has a mounting groove; A first piston and a second piston, which are connected to each other via the piston holder; A bushing, which is installed in the mounting groove, has a sliding groove having a first guide surface and a second guide surface that are parallel to each other and face each other in a first direction. A slider, which fits within the groove, is movable within the groove along a second direction orthogonal to the first direction and is guided by the first guide surface and the second guide surface.

2. The dual-piston assembly according to claim 1, characterized in that, The dual-piston assembly also includes a bearing mounted within the slider.

3. The dual-piston assembly according to claim 2, characterized in that, The dual-piston assembly also includes a bearing housing, which is a metal bearing housing and is installed inside the slider. The bearing is installed inside the bearing housing, and an anti-rotation structure is provided between the slider and the bearing housing to prevent the bearing housing from rotating relative to the slider.

4. The dual-piston assembly according to claim 1, characterized in that, The bushing includes a first bushing body and a second bushing body, which are joined together along the first direction. A first elastic element is provided between the first bushing body and the piston frame for pressing the first bushing body against the second bushing body, and a second elastic element is provided between the second bushing body and the piston frame for pressing the second bushing body against the first bushing body.

5. The dual-piston assembly according to claim 4, characterized in that, The bushing has a first outer surface and a second outer surface. The first outer surface has a first groove, and the second outer surface has a second groove. The first elastic element is disposed in the first groove, and the second elastic element is disposed in the second groove. The first elastic element and the second elastic element are corrugated plates or arc-shaped plates.

6. The dual-piston assembly according to claim 1, characterized in that, The slider has a first working surface and a second working surface that are opposite to each other in the first direction. The first working surface is in sliding contact with the first guide surface, and the second working surface is in sliding contact with the second guide surface.

7. The dual-piston assembly according to claim 1, characterized in that, The slider has a first working surface and a second working surface opposite to each other in the first direction. A plurality of first rolling elements are provided between the first working surface and the first guide surface, and a plurality of second rolling elements are provided between the second working surface and the second guide surface. The first working surface is provided with a first receiving groove for accommodating the first rolling elements, and the second working surface is provided with a second receiving groove for accommodating the second rolling elements.

8. The dual-piston assembly according to claim 1, characterized in that, The wear coefficient of the bushing is less than that of the slider.

9. The dual-piston assembly according to claim 1, characterized in that, The first guide surface and the second guide surface are provided with a wear-resistant coating.

10. The dual-piston assembly according to claim 1, characterized in that, The bushing is made of metal, and the slider is made of polytetrafluoroethylene composite material or polyetheretherketone composite material.

11. The dual-piston assembly according to any one of claims 1-10, characterized in that, At least one of the first piston and the second piston is provided with a valve plate. The valve plate includes a plate body with a groove extending through the plate body along its thickness direction. The groove divides the plate body into a sealing part, a mounting part, and a plurality of swing arms. The sealing part and the mounting part are concentric with each other. The mounting part is arranged around the sealing part. A first end of each swing arm is connected to the sealing part, and a second end of each swing arm is connected to the mounting part. When the number of swing arms is even, the plurality of swing arms are arranged in pairs, and two swing arms in the same pair are centrally symmetrical with respect to the center of the sealing part. When the number of swing arms is odd, the plurality of swing arms are evenly arranged around the center of the sealing part along the circumference of the sealing part.

12. The dual-piston assembly according to claim 11, characterized in that, The sealing part is circular, the mounting part is annular, the swing arm is arc-shaped, there are two swing arms and they are symmetrical about each other with respect to the center of the sealing part, there are two slots, each slot includes an arc-shaped outer slot segment, an arc-shaped inner slot segment and a connecting slot segment connecting the outer slot segment and the inner slot segment, one swing arm is located between the outer slot segment of one slot and the inner slot segment of the other slot, and the other swing arm is located between the inner slot segment of one slot and the outer slot segment of the other slot.

13. The dual-piston assembly according to claim 11, characterized in that, The sealing part is circular, the mounting part is annular, the swing arm is arc-shaped, there are three swing arms and they are evenly arranged around the center of the sealing part along the circumference of the sealing part. There are three slots, each slot including an arc-shaped outer slot segment, an arc-shaped inner slot segment and a connecting slot segment connecting the outer slot segment and the inner slot segment. Each swing arm is located between the outer slot segment of one slot and the inner slot segment of another slot.

14. A two-stage compressor, characterized in that, include: A cylinder having a first compression chamber and a second compression chamber; A dual-piston assembly, wherein the dual-piston assembly is according to any one of claims 1-13, wherein the first piston is movably disposed in the cylinder for compressing gas in the first compression chamber, and the second piston is movably disposed in the cylinder for compressing gas in the second compression chamber, and the first compression chamber and the second compression chamber are connected by a communicating air passage through the piston frame, the first piston and the second piston; A driving device, which is connected to the slider, is used to drive the slider to slide within the groove.

15. The two-stage compressor according to claim 14, characterized in that, The drive device includes a motor and a crankshaft. The motor has a motor shaft. The crankshaft includes a main shaft portion and an eccentric shaft portion. The first end of the eccentric shaft portion is rotatably connected to the slider. The second end of the eccentric shaft portion is connected to the main shaft portion. The main shaft portion is coaxially connected to the motor shaft. The central axis of the eccentric shaft portion is eccentric relative to the central axis of the motor shaft.

16. The two-stage compressor according to claim 15, characterized in that, The drive device also includes a planetary reduction gear assembly, and the motor shaft is connected to the main shaft through the planetary reduction gear assembly.

17. The two-stage compressor according to claim 16, characterized in that, The planetary reduction gear assembly includes an internal gear ring, a planet carrier, a sun gear, and multiple planet gears. The planet gears are rotatably mounted on the planet carrier via planet gear shafts. The sun gear is mounted on the motor shaft. The internal gear ring is connected to the motor housing of the motor. The planet gears mesh with the sun gear and the internal gear ring respectively. The main shaft is connected to the planet carrier. The central axis of the main shaft is coaxial with the central axis of the planet carrier, the central axis of the internal gear ring, and the central axis of the motor shaft.

18. The two-stage compressor according to claim 17, characterized in that, The planetary carrier is integrally formed with the main shaft, one end of the main shaft is provided with an assembly hole, and the second end of the eccentric shaft is fitted into the assembly hole.

19. The two-stage compressor according to claim 15, characterized in that, The motor is a DC motor, and the motor speed is greater than 4000 rpm.

20. A vehicle, characterized in that, include: The pneumatic device and the secondary compressor according to any one of claims 14-19, wherein the secondary compressor is connected to the pneumatic device for supplying compressed air to the pneumatic device.

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