DOUBLE-PISTON ASSEMBLY, TWO-STAGE COMPRESSOR, AND VEHICLE

Abstract

A double-piston assembly includes a piston frame, a first piston, a second piston, a bushing, and a slider. The piston frame has a mounting groove, the first piston and the second piston are connected to each other through the piston frame, the bushing is mounted in the mounting groove, and the bushing has a sliding groove. 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. The slider is fitted in the sliding groove, and the slider is movable in the sliding groove along a second direction orthogonal to the first direction and guided by the first guide surface and the second guide surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefits of and priorities to Chinese Patent Application No. 202520353456X, filed on Feb. 28, 2025, and Chinese Patent Application No. 2025102378944, filed on Feb. 28, 2025. The entire contents of the aforementioned patent applications are incorporated herein by reference for all purposes.

TECHNICAL FIELD

This present technology relates to the field of compressors and, more particularly, to a double-piston assembly, a two-stage compressor, and a vehicle.

BACKGROUND

A compressor is a widely used air compression device, also commonly referred to as an air pump, which is a machine that increases the pressure of a gas (often air) by reducing its volume, then delivers that pressurized gas for storage or immediate use. It powers tools and systems across many industries—like pneumatic wrenches, spray painting, HVAC, and process equipment—by converting electrical or mechanical energy into compressed air energy. In the automotive fields, compressors can be widely used for a variety of applications, support tire inflation, operate pneumatic tools in repair shops, and enable systems like air suspension and turbocharging/supercharging for engine performance.

SUMMARY

Disclosed are devices, systems, and methods for a double-piston assembly with low manufacturing cost and long service life and a two-stage compressor incorporating a double-piston assembly in accordance with the present technology. Also disclosed are vehicles having the two-stage compressor in accordance with the present technology.

In some embodiments, a double-piston assembly in accordance with the present technology includes a piston frame, a first piston, a second piston, a bushing, and a slider. The piston frame defines a mounting groove. The first piston and the second piston are connected to each other through the piston frame. The bushing is mounted in the mounting groove. A sliding groove is defined in the bushing. 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 slider is fitted in the sliding groove, and the slider is movable in the sliding groove along a second direction (B) orthogonal to the first direction and guided by the first guide surface and the second guide surface.

In some embodiments, a double-piston assembly in accordance with the present technology has a more compact structure and may reciprocate in a smaller space. In addition, by arranging the bushing in the piston frame, the slider slides in the sliding groove of the bushing. The entire piston frame does not need to be made of wear-resistant materials, nor does it need to undergo wear-resistant treatment. After the bushing is worn, only the bushing needs to be repaired, for example, by spraying wear-resistant coatings on the first guide surface and the second guide surface, or only replacing the bushing without replacing the entire piston frame, which reduces manufacturing and maintenance costs and improves the service life of the piston frame.

In some embodiments, a two-stage compressor in accordance with the present technology includes a cylinder, a double-piston assembly, and a driving device. The cylinder has a first compression chamber and a second compression chamber. The double-piston assembly is the double-piston assembly described in the above embodiments. The first piston is movably disposed in the cylinder and configured to compress gas in the first compression chamber. The second piston is movably disposed in the cylinder and configured to compress gas in the second compression chamber. The first compression chamber is in communication with the second compression chamber through a communicating air passage passing through the piston frame, the first piston, and the second piston. The driving device is connected to the slider and configured to drive the slider to slide in the sliding groove.

In some aspects, a vehicle according to embodiments of the present technology includes a pneumatic device and the two-stage compressor described in the above embodiments. In such embodiments, the two-stage compressor can be connected to the pneumatic device and configured to supply compressed air to the pneumatic device.

The subject matter described in this patent document can be implemented in specific ways that provide one or more of the following features.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view of an example embodiment of a double-piston assembly in accordance with the present technology.

FIG. 2 shows a side view of the double-piston assembly according to the example embodiment of FIG. 1.

FIG. 3 shows a sectional view of the double-piston assembly according to the example embodiment of FIG. 1.

FIG. 4 shows an exploded view of an example embodiment of a two-stage compressor in accordance with the present technology.

FIG. 5 shows a sectional view of the two-stage compressor according to example embodiments in accordance with the present technology.

FIG. 6 shows a sectional view of a cylinder liner of the example two-stage compressor according to example embodiments in accordance with the present technology.

FIG. 7 shows a partial exploded view of another example embodiment of a double-piston assembly in accordance with the present technology.

FIG. 8 shows an exploded view of the double-piston assembly according to the example embodiment of FIG. 7.

FIG. 9 shows a sectional view of the double-piston assembly according to the example embodiment of FIG. 7.

FIG. 10 shows an exploded view of another example embodiment of a double-piston assembly in accordance with the present technology.

FIG. 11 shows a sectional view of the double-piston assembly according to the example embodiment of FIG. 10.

FIG. 12 shows an exploded view of another example embodiment of a double-piston assembly in accordance with the present technology.

FIG. 13 shows a sectional view of the double-piston assembly according to the example embodiment of FIG. 12.

FIG. 14 shows a schematic view of an example embodiment of a valve plate of an example two-stage compressor in accordance with the present technology.

FIG. 15 shows a sectional view of an example embodiment of a valve plate of an example two-stage compressor in accordance with the present technology.

FIG. 16 shows a sectional view of another example embodiment of a valve plate of an example two-stage compressor in accordance with the present technology.

FIG. 17 shows a partial schematic view of an example embodiment of a valve plate of an example two-stage compressor in a closed state in accordance with the present technology.

FIG. 18 shows a partial schematic view of an example embodiment of a valve plate of an example two-stage compressor in an open state in accordance with the present technology.

FIG. 19 shows an exploded view of an example embodiment of a two-stage compressor in accordance with the present technology.

FIG. 20 shows a sectional view of an example embodiment of a two-stage compressor in accordance with the present technology.

FIG. 21 shows a sectional view of an example embodiment of a planetary reduction assembly and a motor of an example two-stage compressor after assembly in accordance with the present technology.

FIG. 22 shows an exploded view of an example embodiment of a planetary reduction assembly and a motor of an example two-stage compressor in accordance with the present technology.

FIG. 23 shows a perspective view of an example embodiment of a crankshaft of an example two-stage compressor in accordance with the present technology.

FIG. 24 shows a perspective view of an example embodiment of a vehicle in accordance with the present technology.

DETAILED DESCRIPTION

An air pump may be used to supply compressed air to a pneumatic device, such as an air spring, in various vehicles, including but not limited to an off-road vehicle, a sport utility vehicle (SUV), a passenger vehicle, and a commercial vehicle.

To improve compression efficiency, conventionally, a two-stage compressor has been proposed. For instance, existing two-stage compressors can have two pistons rigidly connected to each other via a piston frame, where the piston frame is connected to a drive shaft through a crank-connecting rod mechanism, and the two pistons are radially opposed relative to a rotational axis of the drive shaft. However, due to a large size of a connecting rod in the crank-connecting rod mechanism, a space required for movement of the crank-connecting rod mechanism is large, which results in a large size of the compressor and makes it difficult to miniaturize. Also, another example of a conventional two-stage compressor includes a piston frame that is connected to a drive shaft via a sliding groove guide device. However, this two-stage compressor also suffers from problems such as high manufacturing cost, short service life, and high noise after being used for a period of time. Thus, new configurations and approaches are needed for compressors to meet the needs of low manufacturing costs, long service life, and low noise production.

Disclosed are devices, systems, and methods for a double-piston assembly with low manufacturing cost and long service life and a two-stage compressor incorporating a double-piston assembly in accordance with the present technology. Also disclosed are vehicles having the two-stage compressor in accordance with the present technology.

A double-piston assembly according to example embodiments in accordance with the disclosed technology is described below with reference to the accompanying drawings.

As shown in various drawings among FIGS. 1 to 24, some example embodiments of a double-piston assembly 2, in accordance with the present technology, includes a piston frame 21, a first piston 221, a second piston 222, a bushing 23, and a slider 24.

The piston frame 21 may also be referred to as a piston rod. The first piston 221 and the second piston 222 are connected to each other through the piston frame 21. In other words, the piston frame 21 has a first end and a second end along a length direction of the piston frame 21. 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.

A mounting groove 211 is provided in the piston frame 21. In some embodiments, a cross-section of a middle portion of the piston frame 21 is enlarged, and the mounting groove 211 is formed in the middle portion of the piston frame 21. The bushing 23 is mounted in the mounting groove 211. In some embodiments, the bushing 23 is detachably mounted into the mounting groove 211. In some embodiments, the bushing 23 may be press-fitted into the mounting groove 211 through a cold pressing process or a hot pressing process.

A sliding groove 231 is provided in the bushing 23, 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 a first direction A, and the first guide surface 2311 and the second guide surface 2312 are parallel to each other.

The slider 24 is fitted in the sliding groove 231, and the slider 24 is movable in the sliding groove 231 along a second direction B, in which the second direction B is orthogonal to the first direction A. The slider 24 is guided by the first guide surface 2311 and the second guide surface 2312 to slide in the sliding groove 231.

In some examples, the first direction A may be the length direction of the piston frame 21, and the second direction B may be a width direction of the piston frame 21.

In some specific examples, the first piston 221 and the second piston 222 may differ in size. In some embodiments, the first piston 221 has a larger diameter than the second piston 222. The first piston 221 may be referred to as a low-pressure side piston, and the second piston 222 may be referred to as a high-pressure side piston. Any air after a primary compression by the first piston 221 may be further subjected to a secondary compression by the second piston 222.

In the double-piston assembly 2 according to the embodiments of the present technology, the slider 24 is driven by a driving device 9 to reciprocate in the sliding groove 231, so as to drive the first piston 221 and the second piston 222 to compress air.

For example, compared with traditional crank-connecting rod mechanisms adopted in the related art, the double-piston assembly according to example embodiment of the present technology adopts the slider and sliding groove structure, which is more compact in structure and may enable reciprocating motion in a smaller space, which is beneficial to the miniaturization of the double-piston assembly. In addition, for example, in the double-piston assembly according to example embodiments of the present technology, by incorporating the bushing in the piston frame, the slider slides in the sliding groove of the bushing; during manufacturing, the entire piston frame does not need to be made of a wear-resistant material, nor does it need to be subjected to a wear-resistant treatment, thus reducing the costs, moreover, after a wear occurs in the bushing, only a worn surface of the bushing needs to be repaired. In some embodiments, for example, wear-resistant coatings are sprayed on the first guide surface and the second guide surface, or only the bushing is replaced without replacing the entire piston frame, which reduces the manufacturing and maintenance costs and improves the service life of the piston frame.

As shown in FIGS. 1 to 20, in some example embodiments, the first piston 221 and/or the second piston 222 are provided with valve plates 8. In some examples, as shown in FIG. 1, 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. The first valve plate 801 and the second valve plate 802 may be referred to as intake valve plates, and here, the first valve plate 801 and the second valve plate 802 may be collectively referred to as the valve plates 8.

As shown in FIGS. 14-18, the valve plate 8 includes a plate body 81, the plate body 81 is provided with a slot 82, and the slot 82 penetrates through the plate body 81 along a thickness direction of the plate body 81. The slot 82 partitions 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, a center of the sealing portion 83 coincides with a center of the mounting portion 84, and the mounting portion 84 is arranged around the sealing portion 83.

Each swing arm 85 is an elastic arm, and a width of the swing arm 85 is generally constant along a length direction of the swing arm 85. A first end of the swing arm 85 is connected to the sealing portion 83, and a second end of the swing arm 85 is connected to the mounting portion 84.

When an even number of swing arms 85 are provided, 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. 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 coincides with another swing arm 85 in the same pair after rotating 180 degrees. When an odd number of swing arms 85 are provided, the plurality of swing arms 85 are uniformly arranged around the center of the sealing portion 83 along a circumferential direction of the sealing portion 83. In some embodiments, an N number of swing arms 85 are provided, in which N is an odd number, and among two adjacent swing arms 85, one swing arm 85 coincides with another swing arm 85 after rotating 360/N degrees around the center of the sealing portion 83.

In embodiments of the present technology, the plurality of swing arms 85 are centrally symmetric to each other or uniformly arranged along the circumferential direction of the sealing portion 83, which improves a stress uniformity of the sealing portion 83 and improves a uniformity of the valve plate 8 in opening and closing a valve port.

In some embodiments, a thickness of the plate body 81 may be greater than or equal to 0.1 mm and less than or equal to 0.5 mm, such as 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm.

The valve plate 8 may be a metal sheet, such as a stainless steel sheet or an alloy sheet. In some embodiments, the valve plate 8 may also be made of a non-metallic sheet, such as a resin sheet whose flexibility and strength meet the design requirements.

A width of the slot 82 should ensure that there is no mutual interference between the swing arm 85, the sealing portion 83 and the mounting portion 84 during the use of the valve plate 8. In some embodiments, a width H of the swing arm 85 may be greater than or equal to 1.3 mm and less than or equal to 5 mm, and the width of the slot 82 may be greater than or equal to 1 mm and less than or equal to 4 mm. If the swing arm 85 is too narrow, it will cause fatigue deformation of the valve plate 8 after being used for a period of time; if the swing arm 85 is too wide, it will affect the sensitivity of the sealing portion 83 in opening and closing the valve port. The slot 82 may be formed by stamping a metal sheet. In other words, the valve plate 8 is integrally formed by stamping a metal sheet.

Compared with a valve plate in the related art, in embodiments of the present technology, the valve plate has a uniform opening height, the valve port having the same opening height has a larger flow area, a smoother air flow, a lower air resistance, and a higher response speed. In addition, the swing arms are centrally symmetric to each other or uniformly arranged along the circumferential direction of the sealing portion, so that the sealing portion is stressed uniformly, which not only improves the sensitivity of the opening and closing of the valve plate, but also reduces the fatigue of the valve plate after being used for a period of time, thus prolonging the service life of the valve plate.

In addition, compared with the change in the width of the swing arm of the valve plate in the related art, in embodiments of the present technology, the swing arm has a substantially consistent width along the length direction of the swing arm, thus further improving the stress uniformity of the sealing portion and the uniformity of the opening and closing of the valve port, and further improving the response speed and sensitivity of the valve plate.

In some specific examples, as shown in FIGS. 14 and 15, the plate body 81 may 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 arc-shaped, the width H of the swing arm 85 may be 5 mm, and two swing arms 85 are provided and centrally symmetric to each other with respect to the center of the sealing portion 83. The swing arm 85 is connected to the sealing portion 83 through a first connecting portion 86 and connected to the mounting portion 84 through a second connecting portion 87, so that the width of the swing arm 85 may be more uniform, thus further improving the uniformity of the valve plate 8 in opening and closing the valve port.

Two slots 82 are provided, and 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 FIG. 15, one swing arm 85 is located between the outer slot section 821 of one slot 82 and the inner slot section 822 of another slot 82, and another swing arm 85 is located between the inner slot section 822 of the one slot 82 and the outer slot section 821 of the other slot 82.

The outer slot section 821 and the inner slot section 822 each are arc-shaped, and the connecting slot section 823 includes a plurality of arc segments with different protruding directions smoothly connected to each other. Central angles, denoted as θ, of the inner slot section 822 and the outer slot section 821 are equal, and in some examples, the central angle θ is greater than or equal to 120 degrees and less than or equal to 150 degrees. In an embodiment shown in FIGS. 14 and 15, the central angle θ is 120 degrees.

In other specific examples, as shown in FIG. 16, the plate body 81 may be a stainless steel sheet with a thickness of 0.3 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 arc-shaped, the width H of the swing arm 85 may be 4 mm, and three swing arms 85 are provided and are uniformly arranged around the center of the sealing portion 83 along the circumferential direction 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.

Three slots 82 are provided, and 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 FIG. 16, each swing arm 85 is located between the outer slot section 821 of one slot 82 and the inner slot section 822 of another adjacent slot 82. The outer slot section 821 and the inner slot section 822 each are arc-shaped, and in some embodiments, the central angle θ is greater than or equal to 60 degrees and less than or equal to 90 degrees.

The installation and operation of the valve plate is described below by taking the valve plate (i.e., the second valve plate) provided on the second piston as an example.

As shown in FIGS. 17 and 18, the second piston 222 is provided with a valve plate mounting groove 202, and the second valve plate 802 is mounted in the valve plate mounting groove 202. The mounting portion 84 is fixed by a fixing portion 223 on the second piston 222, and the sealing portion 83 faces a port, also referred as the valve port, of a communicating air passage 201 passing through the second piston 222.

In some embodiments, a flange 224 surrounding the valve port is provided on a surface of the second piston 222, and an upper surface of the flange 224 may be referred to as a sealing surface. As shown in FIG. 17, in a case where an air pressure in the communicating air passage 201 is less than a sum of an elastic force of the swing arm 85 and an air pressure in a compression chamber (i.e., a second compression chamber 1022), the valve plate 8 is pressed against the upper surface of the flange 224 to close the valve port. As shown in FIG. 18, in a case where the air pressure in the communicating 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, a gas in the communicating air passage 201 pushes the sealing portion 83 to translate upward away from the sealing surface, thereby opening the valve port, and an air flow F in the communicating air passage 201 enters the second compression chamber 1022 through the slot 82 of the valve plate 8.

A double-piston assembly according to a first embodiment of the present technology is described below with reference to the accompanying drawings.

As shown in FIGS. 1 to 3, the double-piston assembly 2 includes a piston frame 21, a first piston 221, a second piston 222, a bushing 23, a slider 24, and a bearing 25.

The piston frame 21 has a first end and a second end along a length direction of the piston frame 21. The first piston 221 is provided at the first end of the piston frame 21, and the second piston 222 is provided at the second end of the piston frame 21.

The first piston 221 includes 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, and the first piston ring 2212 is fitted in the first piston ring groove. The compression ring 2213 is sleeved over the first piston head 2211, the compression ring 2213 has a first guide ring groove, and the first guide ring 2214 is fitted in the first guide ring groove.

As illustrated in FIG. 5, the first piston head 2211 is provided with an air intake through hole 22111, and external air enters a first compression chamber 1021 through the air intake through hole 22111. A first valve plate 801 is provided on a surface of the first piston head 2211, and the first valve plate 801 may be the valve plate 8 according to the above embodiments, which is configured to open and close a port, i.e., the valve port, of the air intake through hole 22111. As shown in FIG. 1, in this embodiment, two first valve plates 801 are provided, and correspondingly, two air intakes through holes 22111 are provided to meet the air intake requirement.

The second piston 222 includes 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, 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.

As shown in FIG. 3, the double-piston assembly 2 includes a communicating air passage 201 passing through the first piston 221, the piston frame 21, and the second piston 222. A second valve plate 802 is provided on a surface of the second piston head 2221 for opening and closing a port, i.e., the valve port, of the communicating air passage 201, and the second valve plate 802 may be the valve plate 8 according to the above embodiments.

A middle portion of the piston frame 21 has a substantially rectangular mounting groove 211. The bushing 23 is in a shape of a rectangular ring, and the bushing 23 is detachably mounted in the mounting groove 211. In some embodiments, the bushing 23 is press-fitted into the mounting groove 211 through a hot pressing process or a cold pressing process. An inner cavity of the bushing 23 forms a sliding groove 231. The sliding groove 231 is substantially rectangular and has a first guide surface 2311 and a second guide surface 2312 facing each other in a first direction A. The first guide surface 2311 and the second guide surface 2312 are provided with wear-resistant coatings to improve the wear resistance of the bushing 23. The wear-resistant coatings may be formed on the first guide surface 2311 and the second guide surface 2312 by a spraying process or an electroplating process.

The slider 24 is slidably fitted in the sliding groove 231 along a second direction B orthogonal to the first direction A. Specifically, the slider 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.

A wear coefficient of the slider 24 is greater than a wear coefficient of the bushing 23. In other words, the bushing 23 is more wear-resistant than the slider 24, thus prolonging the service life of the bushing 23. The slider 24 is easier to be replaced than the bushing 23, which may improve maintenance efficiency.

In some embodiments, the bushing 23 may be made of metal, and the slider 24 may be made of a low-friction coefficient composite material, such as a polytetrafluoroethylene-based (PTFE-based) composite material or a polyetheretherketone-based (PEEK-based) composite material, or the surface of the slider 24 may be provided with a composite material layer with a low friction coefficient. In some embodiments, the composite material or composite material layer may be formed by PTFE-based composite material filled with graphite, copper powder, carbon fiber, or glass fiber.

The slider 24 has a slider hole 243, and the bearing 25 is fitted in the slider hole 243. The bearing 25 may be connected to a drive shaft that drives the double-piston assembly 2, so that the slider 24 is driven to slide back and forth in the sliding groove 231, thereby driving the first piston 221 and the second piston 222 to move.

A double-piston assembly according to a second embodiment of the present technology is described below with reference to the accompanying drawings.

As shown in FIGS. 7 to 9, the double-piston assembly 2 includes a piston frame 21, a first piston 221, a second piston 222, a bushing 23, a slider 24, a bearing block 26, and a bearing 25.

The slider 24 has a slider hole 243, and the bearing block 26 is mounted in the slider hole 243. An anti-rotation structure configured to prevent the bearing block 26 from rotating relative to the slider 24 is provided between the slider 24 and the bearing block 26. In an example, the anti-rotation structure includes a retaining groove 244 and a lug 261. The retaining groove 244 may be provided in an end face of the slider 24, and the lug 261 is provided on the bearing block. The lug 261 is fitted in the retaining groove 244, thus preventing the bearing block 26 from rotating relative to the slider 24 and improving the firmness of the bearing block 26. The bearing block 26 has a block hole 262, and the bearing 25 is mounted in the block hole 262 of the bearing block 26. In an alternative example, the slider hole 243 is in a non-circular shape, and the bearing block 26 may have a corresponding non-circular cross-section profile matching the slider hole 243, so that when the bearing block 26 is mounted in the slider hole 243, the bearing block 26 may be prevented from rotating relative to the slider 24. In this example, the non-circular slider hole and the non-circular cross-section profile of the bearing block together constitute the anti-rotation structure.

The bearing block may be a metal bearing block, and the slider may be made of a resin composite material, such as a polytetrafluoroethylene-based (PTFE-based) composite material or a polyetheretherketone-based (PEEK-based) composite material. Since the bearing block is the metal bearing block, during the operation of the double-piston assembly, the bearing block is less likely to thermally expand compared with the slider, so that the bearing is less likely to be loosened in the bearing block, thus improving the firmness of the bearing and minimizing noise.

Other aspects of the double-piston assembly according to the second embodiment of the present technology may be similar to those of the double-piston assembly according to the above embodiments, and will not be repeated here.

A double-piston assembly according to a third embodiment of the present technology is described below with reference to the accompanying drawings.

As shown in FIGS. 10 to 11, the double-piston assembly 2 includes a piston frame 21, a first piston 221, a second piston 222, a bushing 23, a slider 24, a bearing block 26, and a bearing 25.

The bushing 23 includes a first bushing body 232 and a second bushing body 233. The first bushing body 232 and the second bushing body 233 each are U-shaped, and the first bushing body 232 and the second bushing body 233 are butted against each other in a first direction A to define a sliding groove 231 in the bushing 23. In some embodiments, the first bushing body 232 and the second bushing body 233 are symmetrical to each other. By splitting the bushing 23 into the first bushing body 232 and the second bushing body 233, the processing of the bushing 23 may be simplified, and the first bushing body 232 and the second bushing body 233 may be replaced individually, thus reducing manufacturing and maintenance costs.

The first bushing body 232 has a first outer surface, which is provided with a first groove 2321. A first elastic member 2322 is arranged in the first groove 2321, and the first elastic member 2322 abuts between the mounting groove 211 and the first bushing body 232. The second bushing body 233 has a second outer surface, which is provided with a second groove 2331. A second elastic member 2332 is disposed in the second groove 2331, and the second elastic member 2332 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 toward each other by the first elastic member 2322 and the second elastic member 2332. In some embodiments, the first elastic member 2322 and the second elastic member 2332 are corrugated plates or arc-shaped plates.

The first elastic member and the second elastic member may ensure reliable butting between the first bushing body and the second bushing body, reliable contact between the first guide surface of the first bushing body and the first working surface of the slider, and reliable contact between the second guide surface of the second bushing body and the second working surface of the slider, thereby reducing impact noise during the sliding and reversing of the slider.

Other aspects of the double-piston assembly of the third embodiment of the present technology may be similar to those of the double-piston assembly according to the above embodiments and will not be repeated here.

A double-piston assembly according to a fourth embodiment of the present technology is described below with reference to the accompanying drawings.

As shown in FIGS. 12 to 13, the double-piston assembly 2 includes a piston frame 21, a first piston 221, a second piston 222, a bushing 23, a slider 24, and a bearing 25.

A sliding groove 231 defined in the bushing 23 has a first guide surface 2311 and a second guide surface 2312. The slider 24 has a first working surface 241 and a second working surface 242. A plurality of first rolling elements 2412 are disposed between the first working surface 241 and the first guide surface 2311, and a plurality of second rolling elements 2422 are disposed between the second working surface 242 and the second guide surface 2312. In some embodiments, the first rolling elements 2412 and the second rolling elements 2422 are cylinders. The first working surface 241 has a first accommodating groove 2411, and the plurality of first rolling elements 2412 are disposed in the first accommodating groove 2411. The second working surface 242 has a second accommodating groove 2421, and the plurality of second rolling elements 2422 are disposed in the second accommodating groove 2421. It may be understood that a part of the first rolling elements 2412 is exposed from the first accommodating groove 2411 to maintain contact with the first guide surface 2311 of the bushing 23, and a part of the second rolling elements 2422 is exposed from the second accommodating groove 2421 to maintain contact with the second guide surface 2312 of the bushing 23.

By providing the first rolling elements 2412 and the second rolling elements 2422, when the slider 24 moves in the sliding groove 231, a rolling friction occurs between the slider 24 and the bushing 23, which reduces wear on the slider 24 and the bushing 23. In addition, the requirements for processing precision of the bushing 23 and the slider 24 are reduced, thus lowering manufacturing costs. The first guide surface 2311, the second guide surface 2312, a groove surface of the first accommodating groove 2411, and a groove surface of the second accommodating groove 2421, as well as surfaces of the first rolling elements 2412 and the second rolling elements 2422, may be hard surfaces that have been polished, with a surface hardness ≥50 HRC and a surface roughness ≤Ra0.8.

Other aspects of the double-piston assembly of the fourth embodiment of the present technology may be similar to those of the double-piston assembly according to the above embodiments and will not be repeated here.

A two-stage compressor according to embodiments of the present technology is described below with reference to the accompanying drawings.

As shown in FIGS. 1 to 24, the two-stage compressor 10012 according to the embodiments of the present technology includes a cylinder 1, a double-piston assembly 2, and a driving device 9.

The cylinder 1 includes a cylinder block 11 and a cylinder head 13. The cylinder head 13 is mounted on the cylinder block 11. In some embodiments, the cylinder head 13 is detachably connected to the cylinder block 11 via bolts. The cylinder block 11 has a first cylinder chamber 1011 and a second cylinder chamber 1012. The cylinder block 11 has an air inlet 113, and the cylinder block 11 has an air intake passage 111 in communication with the air inlet 113.

The double-piston assembly 2 may be the double-piston assembly 2 according to the above embodiments. The first piston 221 is movably fitted in the first cylinder chamber 1011 to define 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 to define a second compression chamber 1022 in the second cylinder chamber 1012. The first compression chamber 1021 is in communication with the second compression chamber 1022 via the communicating air passage 201 passing through the piston frame 21, the first piston 221, and the second piston 222.

An air intake passage 111 in the cylinder block 11 is in communication with the first compression chamber 1021 via the air intake through hole 22111 in the first piston head 2211, so as to enable external gas to enter the first compression chamber 1021 from the air inlet 113 through the air intake passage 111 and the air intake through hole 22111. The gas compressed in the first compression chamber 1021 enters the second compression chamber 1022 through the communicating air passage 201 for re-compression. The first compression chamber 1021 may be referred to as a primary or low-pressure compression chamber, and the second compression chamber 1022 may be referred to as a secondary or high-pressure compression chamber.

The driving device 9 includes a motor 4 and a crankshaft 5. The motor 4 has a motor shaft 41, and the crankshaft 5 includes a main shaft portion 51 and an eccentric shaft portion 52. A first end of the eccentric shaft portion 52 is pivotally connected to the slider 24, and a second end of the eccentric shaft portion 52 is connected to the main shaft portion 51. The main shaft portion 51 is coaxially connected to the motor shaft 41, and a central axis of the eccentric shaft portion 52 is eccentric with respect 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, thereby driving the first piston 221 to reciprocate in the first compression chamber 1021 and the second piston 222 to reciprocate in the second compression chamber 1022 through the piston frame 21.

Compared with compressors in the related art that use crank-connecting rod mechanisms, the two-stage compressor according to the embodiments of the present technology adopts a structure of slider and sliding groove combination, a size of the piston frame is reduced, a length of the communicating air passage is shortened, a clearance volume of the low-pressure chamber is reduced, a volumetric efficiency of the two-stage compressor is improved, and the two-stage compressor has a more compact structure, which is conducive to miniaturization. In addition, the bushing in the piston frame is convenient to be maintained and replaced after wear, and the cost is thus low.

A two-stage compressor according to an embodiment of the present technology is described below with reference to the accompanying drawings.

As shown in FIGS. 4 to 6, the two-stage compressor 10012 includes a cylinder 1, a double-piston assembly 2, a motor 4, a crankshaft 5, and a dryer 7.

The cylinder 1 includes a cylinder block 11, a cylinder head 13, and an exhaust valve 15. The cylinder head 13 is mounted to a lower end of the cylinder block 11. In some embodiments, the cylinder head 13 is detachably connected to the cylinder block 11 via bolts.

The double-piston assembly 2 may be the double-piston assembly 2 according to the above embodiments. The cylinder block 11 has a first cylinder chamber 1011 and a second cylinder chamber 1012. The first piston 221 of the double-piston assembly 2 is movably fitted in the first cylinder chamber 1011 to define 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 to define a second compression chamber 1022 in the second cylinder chamber 1012. The first compression chamber 1021 is in communication with the second compression chamber 1022 via the communicating air passage 201 passing through the piston frame 21, the first piston 221, and the second piston 222.

The first piston 221 has an air intake through hole 22111 in communication with the first compression chamber 1021. The second compression chamber 1022 has an exhaust port 114, and the exhaust valve 15 is disposed at the exhaust port 114. The dryer 7 is connected to the cylinder block 11, so that the compressed air discharged from the second compression chamber 1022 through the exhaust port 114 enters the dryer 7 for drying, and the dried compressed air is discharged from a compressed air outlet (i.e., an air outlet 71) of the dryer 7.

The cylinder block 11 has an air inlet 113. An air intake passage 111 in the cylinder block 11 is in communication with the air inlet 113 and the air intake through hole 22111. The first valve plate 801 is disposed at a port of the air intake through hole 22111 in communication with the first compression chamber 1021. The second valve plate 802 is disposed at a port of the communicating air passage 201 in communication with the second compression chamber 1022.

Cylinder liners 12 are respectively disposed at an upper portion and a lower portion in the cylinder block 11. In other words, an inner cavity of the cylinder liner 12 at the lower portion forms the first cylinder chamber 1011, and an inner cavity of the cylinder liner 12 at the upper portion forms the second cylinder chamber 1012. The cylinder block 11 may be cast, and the cylinder liner 12 may be machined from pipes, so that the wear-resistant treatment process of the cylinder liner 12 is simple, the quality is stable, the machining accuracy is easy to ensure, and there is no need for wear-resistant treatment of the cylinder block 11, thus reducing the cost.

An inner wall surface of the cylinder liner 12 may be a hard surface that has been polished with a microhardness ≥350 HV and a surface roughness ≤Ra0.8. The cylinder liner 12 may be made of materials such as aluminum alloy, carbon steel, and stainless steel, and a surface treatment method may be hard oxidation, hard chrome plating, plasma spraying, or other hard coatings (a wear-resistant layer 121). In some embodiments, an inner wall of an end of the cylinder liner 12 has a bevel 122, which reduces the risk of damage to the piston ring and the guide ring during insertion in the assembly process of the first piston 221 and the second piston 222.

The crankshaft 5 includes a main shaft portion 51 and an eccentric shaft portion 52. A first end of the eccentric shaft portion 52 is pivotally connected to the slider 24 of the double-piston assembly 2, and a second end of the eccentric shaft portion 52 is connected to the main shaft portion 51. The main shaft portion 51 is coaxially connected to a motor shaft 41 of the motor 4, and a central axis of the eccentric shaft portion 52 is eccentric with respect 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, thereby driving the first piston 221 to reciprocate in the first compression chamber 1021 and the second piston 222 to reciprocate in the second compression chamber 1022 through the piston frame 21.

The operation of the two-stage compressor according to the embodiments of the present technology is briefly described below.

The motor 4 drives the slider 24 to slide in the sliding groove 231 through the crankshaft 5 to drive the double-piston assembly 2 to move upward, the first valve plate 801 opens and the second valve plate 802 closes, and external air, denoted as F, enters the first compression chamber 1021 through the air inlet 113, the air intake passage 111, and the air intake through hole 22111 inside the first piston 221 in sequence. When the double-piston assembly 2 moves to a top dead center (TDC) and then changes direction to move downward, the air is compressed in the first compression chamber 1021, the first valve plate 801 closes and the second valve plate 802 opens, and the gas in the first compression chamber 1021 enters the second compression chamber 1022 through the communicating air passage 201. When the double-piston assembly 2 moves to a bottom dead center and then changes direction to move upward again, the air is compressed again in the second compression chamber 1022. Then, the exhaust valve 15 opens, and the compressed gas in the second compression chamber 1022 is discharged into the dryer 7 for drying, and the dried gas is discharged from the air outlet 71. In some embodiments, the dried gas discharged from the air outlet 71 is supplied to a compressed gas application device. This cycle repeats continuously.

A two-stage compressor according to another embodiment of the present technology is described below with reference to the accompanying drawings.

As shown in FIGS. 19 to 23, the two-stage compressor 10012 includes a cylinder 1, a double-piston assembly 2, and a driving device 9.

A cylinder block 11 of the cylinder 1 has a first cylinder chamber 1011 and a second cylinder chamber 1012. The double-piston assembly 2 may be the double-piston assembly 2 according to the above embodiments. The first piston 221 of the double-piston assembly 2 is movably fitted in the first cylinder chamber 1011 to define 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 to define a second compression chamber 1022 in the second cylinder chamber 1012. The first compression chamber 1021 is in communication with the second compression chamber 1022 through the communicating air passage 201.

As shown in FIGS. 19 to 23, the driving device 9 includes a motor 4, a crankshaft 5, and a planetary reduction assembly 3. The motor 4 has a motor shaft 41, and the motor shaft 41 is rotatably connected to the slider 24 of the double-piston assembly 2 through the planetary reduction assembly 3 and the crankshaft 5. The planetary reduction assembly 3 has a large reduction ratio, allowing the motor 4 to be a high-speed motor and requiring less space, thereby reducing the overall size and weight of the two-stage compressor 10012.

In some embodiments, the motor 4 may be a high-speed DC motor, and a rotation speed of the motor 4 may be greater than 4000 revolutions per minute (RPM). In some embodiments, the rotation speed of the motor 4 is greater than 8000 RPM. High-speed motors have a small overall size, a high rotation speed, a small torque, a small rotational inertia, and a fast start-stop response.

In the embodiments of the present technology, by adopting the combination of the high-speed motor and the planetary reduction assembly, the two-stage compressor may quickly respond to load changes while ensuring the stability and accuracy of this response.

Compared with conventional reducers, the planetary reduction assembly has a high transmission efficiency, which may not only reduce the power consumption required by the motor, thereby reducing the energy consumption of the two-stage compressor, but also improve a working efficiency of the two-stage compressor, particularly suitable for automotive compressors.

As shown in FIGS. 21 and 22, the motor 4 includes a motor shaft 41, a motor housing 42, a motor rear end cover 43, a rotor 44, and a stator 45. A rear end of the motor housing 42 has an opening, another end of the motor housing 42 has a hole for the motor shaft 41 to pass through, and a rotor front bearing 46 is mounted in this hole. The motor rear end cover 43 is detachably mounted at the opening of the motor housing 42 through bolts. The motor rear end cover 43 has a groove, and a rotor rear bearing 47 is mounted in this groove. The motor shaft 41 is connected to the rotor 44, the part of the motor shaft 41 passing through the motor housing 42 engages with the rotor front bearing 46, and the end of the motor shaft 41 located in the motor housing 42 engages with the rotor rear bearing 47.

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

The inner gear ring 31 is configured as a fixed gear of the planetary reduction assembly 3. The inner gear ring 31 includes a cylindrical body 311 and an annular boss 312. The annular boss 312 is arranged on an inner circumferential wall of the cylindrical body 311, and inner teeth are formed on an inner circumferential wall surface of the annular boss 312. The annular boss 312 defines a mating hole 301 within the cylindrical body 311, and the mating hole 301 is located at an end of the cylindrical body 311 adjacent to the motor 4. An end of the motor housing 42 is provided with a mating portion 401 with a reduced diameter, and the mating portion 401 is fitted within the mating hole 301. An end of the cylindrical body 311 is butted with an end of the motor housing 42, and an outer circumferential surface of the cylindrical body 311 is flush with an outer circumferential surface of the motor housing 42.

Through the tight fit between the mating hole 301 and the mating portion 401, a spacing between the planetary reduction assembly 3 and the motor 4 is reduced, structural compactness is improved, and overall volume and occupied space are reduced, thereby further reducing the size of the two-stage compressor 10012. In addition, the outer circumferential surface of the cylindrical body 311 is flush with the outer circumferential surface of the motor housing 42, which also improves an overall visual effect. Further, a sealing ring 48 or other sealing elements may be provided between the mating hole 301 and the mating portion 401, so as to improve a sealing performance between the planetary reduction assembly 3 and the motor 4.

As shown in FIG. 22, an end face (i.e., a right-end face in FIG. 22) of the planet carrier 32 facing away from the crankshaft 5 is provided with an assembly groove 321, a rear bearing 322 is mounted in the assembly groove 321, and an end of the motor shaft 41 extending out of the motor housing 42 engages with the rear bearing 322.

The motor shaft 41 drives the sun gear 33 to rotate around a central axis, denoted as X1, and the central axis X1 is a common central axis of the motor shaft 41, the sun gear 33, and the planet carrier 32. The planet gears 34 revolve around the central axis X1 and simultaneously rotate about central axes of the planet gear shafts 35, so that the planet carrier 32 rotates around the central axis X1.

In some embodiments, teeth of the inner gear ring 31 and the planet gears 34 are helical teeth, which may reduce speed, increase torque, and reduce noise.

As shown in FIGS. 21 to 23, the crankshaft 5 includes a main shaft portion 51 and an eccentric shaft portion 52. An end of the main shaft portion 51 is connected to the planet carrier 32. A central axis of the main shaft portion 51 is coaxial with the central axis X1 of the planet carrier 32, the inner gear ring 31 and the motor shaft 41, which is 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 engages with the front bearing 112.

In some embodiments, the main shaft portion 51 and the planet carrier 32 may be integrally formed, thereby improving the overall strength and durability of the crankshaft 5, reducing assembly and maintenance workload for the crankshaft 5, improving structural compactness, reducing overall volume and occupied space, and further reducing the size of the two-stage compressor 10012.

The main shaft portion 51 has a mounting hole 511, an end of the eccentric shaft portion 52 is fitted in the mounting hole 511, and another end of the eccentric shaft portion 52 extends out of the mounting hole 511. A central axis X2 of the eccentric shaft portion 52 is eccentric with respect to the central axis X1 of the main shaft portion 51, and the other end of the eccentric shaft portion 52 engages with the bearing 25 in the piston frame 21.

Since the double-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 during rotation. For this reason, the main shaft portion 51 is provided with a counterweight 53 to reduce or eliminate vibrations caused by the imbalance of the crankshaft 5, thus improving operational stability and reliability of the crankshaft 5, and reducing noise generated by the vibrations of the crankshaft 5.

A vehicle according to embodiments of the present technology is described below with reference to the accompanying drawings.

As shown in FIG. 24, the vehicle 100 according to embodiments of the present technology includes a pneumatic device 1002 and a two-stage compressor 10012. The two-stage compressor 10012 may be the two-stage compressor 10012 according to the above embodiments. The two-stage compressor 10012 is connected to the pneumatic device 1002 and configured to supply compressed air to the pneumatic device 1002. In some embodiments, the pneumatic device 1002 may be an air spring of an air suspension system of the vehicle 100.

In the vehicle according to embodiments of the present technology, the two-stage compressor has compact structure, small size, light weight, miniaturization, and high applicability, thereby effectively addressing the problems of large volume and slow start-up response of conventional automotive compressors in the related art. Therefore, the two-stage compressor according to the embodiments of the present technology may provide a more efficient, compact, and reliable air supply solution for the air suspension system of the vehicle.

Conclusion

Implementations of the subject matter and the functional operations described in this patent document can be implemented in various systems, digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Implementations of the subject matter described in this specification can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a tangible and non-transitory computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more of them. The term “data processing unit” or “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.

A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

The aforementioned example embodiments described above with reference to the accompanying drawings are illustrative. It should be understood that the embodiments described are intended to explain the present technology, but not to limit the present technology.

In the description of the present technology, it should be understood that the orientation or position relationship indicated by the terms “center,” “longitudinal,” “transverse,” “length,” “width,” “thickness,” “up,” “down,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial” and “circumferential,” and the like, is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present technology and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, and be constructed and operated in a specific orientation, so it cannot be understood as a limitation of the present technology.

In addition, the terms “first” and “second” are only used for purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the feature defined as “first” or “second” may explicitly or implicitly include at least one such feature. In the description of the present technology, “a plurality of” means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present disclosure, unless otherwise expressly defined, terms such as “install/mount,” “interconnect,” “connect,” and “fix” shall be understood broadly, and may be, for example, fixed connections, detachable connections, or integral connections; may also be mechanical or electrical connections or intercommunication; may also be direct connections or indirect connections via intervening media; and may also be inner communications or interactions of two elements, unless otherwise specifically defined. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific situations.

In the present disclosure, unless otherwise expressly defined, the first feature “below,” “under,” “on the bottom of,” “above,” “on”, or “on top of” a second feature may include an embodiment in which the first feature is in direct contact with the second feature, or the first feature is in indirect contact with the second feature through an intermediate media. And, the first feature “above,” “on,” or “on top of” the second feature may include an embodiment in which the first feature is right or obliquely “above,” “on,” or “on top of” the second feature, or means that the first feature is at a height higher than that of the second feature. The first feature “below,” “under,” or “on the bottom of” the second feature may include an embodiment in which the first feature is right or obliquely “below,” “under,” or “on the bottom of” the second feature, or means that the first feature is at a height lower than that of the second feature.

In the description of the present technology, terms such as “an embodiment,” “some embodiments,” “an example,” “a specific example,” or “some examples” means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present technology. Thus, the appearances of these terms in various places throughout this specification are not necessarily referring to the same embodiment or example of the present technology. Furthermore, the particular features, structures, materials, or characteristics may be combined in one or more embodiments or examples in any suitable manner. In addition, without contradiction, those skilled in the art may combine and unite different embodiments or examples or features of the different embodiments or examples described in this specification.

Although the embodiments of the present technology have been shown and described above, it can be understood that the above embodiments are illustrative and shall not be understood as limitations to the present technology, and changes, modifications, alternatives and variations can be made in the above embodiments within the scope of the present technology by those skilled in the art.

While this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.

Claims

1. A double-piston assembly, comprising:

a piston frame having a mounting groove;

a first piston and a second piston connected to each other through the piston frame;

a bushing mounted in the mounting groove, wherein the bushing has a sliding groove, wherein 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; and

a slider fitted in the sliding groove, wherein the slider is movable in the sliding 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 double-piston assembly according to claim 1, further comprising a bearing mounted in the slider.

3. The double-piston assembly according to claim 2, further comprising a bearing block, wherein the bearing block is a metal bearing block and is mounted in the slider, the bearing is mounted in the bearing block, and an anti-rotation structure is arranged between the slider and the bearing block and configured to prevent the bearing block from rotating relative to the slider.

4. The double-piston assembly according to claim 1, wherein the bushing comprises a first bushing body and a second bushing body, the first bushing body and the second bushing body are butted against each other along the first direction, a first elastic member is arranged between the first bushing body and the piston frame and configured to press the first bushing body toward the second bushing body, and a second elastic member is arranged between the second bushing body and the piston frame and configured to press the second bushing body toward the first bushing body.

5. The double-piston assembly according to claim 4, wherein the bushing has a first outer surface and a second outer surface, the first outer surface is provided with a first groove, the second outer surface is provided with a second groove, the first elastic member is arranged in the first groove, the second elastic member is arranged in the second groove, and the first elastic member and the second elastic member are corrugated plates or arc-shaped plates.

6. The double-piston assembly according to claim 1, wherein the slider has a first working surface and a second working surface 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 double-piston assembly according to claim 1, wherein 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 arranged between the first working surface and the first guide surface, a plurality of second rolling elements are arranged between the second working surface and the second guide surface, the first working surface is provided with a first accommodating groove configured to accommodate the plurality of first rolling elements, and the second working surface is provided with a second accommodating groove configured to accommodate the plurality of second rolling elements.

8. The double-piston assembly according to claim 1, wherein a wear coefficient of the bushing is smaller than a wear coefficient of the slider.

9. The double-piston assembly according to claim 1, wherein each of the first guide surface and the second guide surface is provided with a wear-resistant coating.

10. The double-piston assembly according to claim 1, wherein the bushing is made of metal, and the slider is made of a polytetrafluoroethylene-based (PTFE-based) composite material or a polyetheretherketone-based (PEEK-based) composite material.

11. The double-piston assembly according to claim 1, wherein at least one of the first piston and the second piston is provided with a valve plate, the valve plate comprises a plate body having a plurality of slots, the plurality of slots penetrate through the plate body along a thickness direction of the plate body, the plurality of slots partition the plate body into a sealing portion, a mounting portion and a plurality of swing arms, the sealing portion and the mounting portion are concentric with each other, the mounting portion is arranged around the sealing portion, a first end of each of the plurality of swing arms is connected to the sealing portion, and a second end of each of the plurality of swing arms is connected to the mounting portion, wherein in a case that a number of the plurality of swing arms is even, the plurality of swing arms are arranged in pairs, and two swing arms in a same pair of swing arms are centrally symmetric to each other with respect to a center of the sealing portion, and wherein in a case that the number of the plurality of swing arms is odd, the plurality of swing arms are uniformly arranged around a center of the sealing portion along a circumferential direction of the sealing portion.

12. The double-piston assembly according to claim 11, wherein the sealing portion is circular, the mounting portion is annular, the plurality of swing arms are arc-shaped, the plurality of swing arms comprise two swing arms centrally symmetric to each other with respect to the center of the sealing portion, the plurality of slots comprises two slots, and each of the two slots comprises an arc-shaped outer slot section, an arc-shaped inner slot section, and a connecting slot section connected between the outer slot section and the inner slot section, wherein one of the two swing arms is located between the outer slot section of one of the two slots and the inner slot section of the other of the two slots, and the other of the two swing arms is located between the inner slot section of the one of the two slots and the outer slot section of the other of the two slots.

13. The double-piston assembly according to claim 11, wherein the sealing portion is circular, the mounting portion is annular, the plurality of swing arms are arc-shaped, the plurality of swing arms comprise three swing arms uniformly arranged around the center of the sealing portion along the circumferential direction of the sealing portion, the plurality of slots comprise three slots, and each of the three slots comprises an arc-shaped outer slot section, an arc-shaped inner slot section, and a connecting slot section connected between the outer slot section and the inner slot section, wherein each of the three swing arms is located between the outer slot section of one of the three slots and the inner slot section of another of the three slots.

14. A two-stage compressor, comprising:

a cylinder having a first compression chamber and a second compression chamber;

a double-piston assembly, comprising: a piston frame having a mounting groove; a first piston and a second piston connected to each other through the piston frame; a bushing mounted in the mounting groove, the bushing having a sliding groove, wherein 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; and a slider fitted in the sliding groove, wherein the slider is movable in the sliding groove along a second direction orthogonal to the first direction and is guided by the first guide surface and the second guide surface, the first piston is movably arranged in the cylinder and is configured to compress gas in the first compression chamber, the second piston is movably arranged in the cylinder and configured to compress gas in the second compression chamber, and the first compression chamber is in communication with the second compression chamber through a communicating air passage passing through the piston frame, the first piston and the second piston; and

a driving device connected to the slider and configured to drive the slider to slide in the sliding groove.

15. The two-stage compressor according to claim 14, wherein the driving device comprises a motor and a crankshaft, wherein the motor has a motor shaft, the crankshaft comprises a main shaft portion and an eccentric shaft portion, a first end of the eccentric shaft portion is rotatably connected to the slider, a 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, and a central axis of the eccentric shaft portion is eccentric relative to a central axis of the motor shaft.

16. The two-stage compressor according to claim 15, wherein the driving device further comprises a planetary reduction assembly, and the motor shaft is connected to the main shaft portion through the planetary reduction assembly.

17. The two-stage compressor according to claim 16, wherein the planetary reduction assembly comprises an inner gear ring, a planet carrier, a sun gear and a plurality of planet gears, the plurality of planet gears are rotatably mounted on the planet carrier through planet gear shafts, the sun gear is mounted on the motor shaft, the inner gear ring is connected to a motor housing of the motor, the plurality of planet gears are meshed with the sun gear and the inner gear ring, the main shaft portion is connected to the planet carrier, and a central axis of the main shaft portion is coaxial with a central axis of the planet carrier, a central axis of the inner gear ring and a central axis of the motor shaft.

18. The two-stage compressor according to claim 17, wherein the planet carrier is integrated with the main shaft portion, an end of the main shaft portion is provided with a mounting hole, and the second end of the eccentric shaft portion is fitted in the mounting hole.

19. The two-stage compressor according to claim 15, wherein the motor is a direct current motor, and a rotation speed of the motor is greater than 4000 revolutions per minute.

20. A vehicle, comprising:

a pneumatic device; and

a two-stage compressor,

wherein the two-stage compressor comprises: a cylinder having a first compression chamber and a second compression chamber; a double-piston assembly, wherein the double-piston assembly comprises: a piston frame having a mounting groove; a first piston and a second piston connected to each other through the piston frame; a bushing mounted in the mounting groove, wherein the bushing has a sliding groove, wherein 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; and a slider fitted in the sliding groove, wherein the slider is movable in the sliding groove along a second direction orthogonal to the first direction and is guided by the first guide surface and the second guide surface, the first piston is movably arranged in the cylinder and is configured to compress gas in the first compression chamber, the second piston is movably arranged in the cylinder and configured to compress gas in the second compression chamber, and the first compression chamber is in communication with the second compression chamber through a communicating air passage passing through the piston frame, the first piston and the second piston; and a driving device connected to the slider and configured to drive the slider to slide in the sliding groove; and

wherein the two-stage compressor is connected to the pneumatic device and configured to supply compressed air to the pneumatic device.