CN213899583U

CN213899583U - Oil-free air compressor multi-point supporting crankshaft structure and oil-free two-stage air compressor

Info

Publication number: CN213899583U
Application number: CN202021687764.XU
Authority: CN
Inventors: 朱彬; 李传武; 钟周乐; 周胜博
Original assignee: Zhejiang Ruili Air Compressor Equipment Co ltd
Current assignee: Zhejiang Ruili Air Compressor Equipment Co ltd
Priority date: 2020-08-13
Filing date: 2020-08-13
Publication date: 2021-08-06
Anticipated expiration: 2030-08-13

Abstract

The utility model provides a multipoint supporting crankshaft structure of an oil-free air compressor and an oil-free two-stage air compressor, the crank structure is connected with a connecting rod of the air compressor, the crank structure is in a three-section type and comprises a first crank, a second crank and a third crank, wherein the first crank and the second crank are symmetrical, the third crank is connected with the first crank and the second crank, wherein the first crank and the second crank are opposite to the third crank, and a first eccentric journal is formed at the butt joint position of the first crank and the third crank, the butt joint position of the third crank and the second crank forms a second eccentric journal, between the first crank and the third crank, and an interference structure is formed between the third crank and the second crank and the transmission positioning pin shaft, so that the problem that the long-stroke oil-free air compressor is difficult to sleeve in the self-lubricating bearing is solved, the shape tolerance of the split crankshaft is ensured, and the transmission reliability of the crankshaft structure is improved.

Description

Oil-free air compressor multi-point supporting crankshaft structure and oil-free two-stage air compressor

Technical Field

The utility model belongs to the technical field of vehicle air compressor, specifically speaking relates to an oilless air compressor machine multiple spot supports crankshaft structure and oilless two-stage air compressor machine.

Background

The air compressor used in the automobile is mainly used as an air source for supplying air to equipment including automobile braking, suspension, door opening and other auxiliary air-using devices, the piston type air compressor is a common automobile electric air compressor, fig. 1 is a sectional view showing a sectional structure in a cylinder of a piston type air compressor of a prior art, referring to fig. 1, the piston air compressor includes two rows of pistons, defined as a first piston 10a and a second piston 20a, the figure shows the distance D between the piston axes of the first piston 10a and the second piston 20a, it is expected that when the air compressor operates the two pistons to reciprocate up and down, inertia force is generated between the crank-link mechanisms of the two pistons due to mass unbalance, and in addition, the distance between the two pistons is larger, so that the inertia moment generated together is also larger.

Reciprocating inertia force F of crank link mechanism_jThe direction of the reciprocating inertia force generated by the piston group and the reciprocating part of the connecting rod is specified to be in the positive direction, and the positive value of the sum of the reciprocating inertia forces generated by the piston group and the reciprocating part of the connecting rod is the value of the force for compressing the connecting rod, and the formula is written as follows:

F_j＝-M_jaj

the reciprocating mass M is known_jEqual to piston group mass M_pAnd connecting rod reciprocating mass Mc1, the reciprocating inertial force can be written as:

F_j＝(M_p+Mc1)rω**2(cosα+λcos2α)

therefore, when the above formula is modified, the reciprocating inertial force is taken as the sum of the two components:

F_j＝M_jrω**2cosα+M_jr ω x 2 λ cos2 α; namely:

F_j＝F_j1+F_j2

wherein, F_j1 is generally referred to as the first order reciprocating inertial force, F_j2 is called the second order reciprocating inertial force.

The maximum value of the first order reciprocating inertial force is 1/lambda of the maximum value of the second order reciprocating inertial force, and the value of lambda is usually in the range of 1/3.5 to 1/6, namely the value of lambda is less than 1, and it can be seen that the first order reciprocating inertial force plays a main role in the reciprocating inertial force.

Under the prior art, the crankshaft connected with the air compressor connecting rod is mostly single in structure, and the technical problem that the whole operation process of the mechanism generates large vibration is difficult to solve. In view of this, should improve prior art, provide a crankshaft of new construction to solve the problem that piston air compressor produced vibration under the operating condition greatly under the prior art.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that overcome prior art not enough, provide one kind and have optimization structure and easily realize, reciprocal, the rotatory inertia that can balance piston crank link mechanism to and reciprocal, rotatory moment of inertia, thereby reduce the vibration in the air compressor machine operation process and can prolong equipment life's oilless air compressor machine multiple spot support crankshaft structure and oilless two-stage air compressor machine.

For solving above technical problem, the utility model discloses an oil-free air compressor machine multiple spot supports crank structure, this crank structure and air compressor machine connecting rod are connected, crank structure is the syllogic, including the first crank and the second crank of symmetry and connect first crank and the articulate third crank of second, wherein, first crank and second crank with the third crank opposition distributes, then first crank and third crank butt joint position form first eccentric journal, the third crank with second crank butt joint position forms the eccentric journal of second, between first crank and the third crank, and form the interference structure with the drive pin axle between third crank and the second crank.

Preferably, the space between the first crank and the third crank, and the space between the third crank and the second crank are pressed and fixed with the inner ring of the maintenance-free bearing,

further preferably, the end of the first crank not connected to the third crank, and the end of the second crank not connected to the third crank, are formed with main journals, wherein both the main journals and the third crank journal are provided with support bearings.

Still further preferably, the maintenance-free bearing is a maintenance-free double-row bearing, and two roller bearing raceways are uniformly distributed at two ends of the first crank, the second crank and the third crank.

Preferably, the first crank, the second crank and the third crank are fixed with the transmission positioning pin shaft through flanging in a riveting mode.

Correspondingly, the utility model also provides an utilize aforementioned oil-free two-stage air compressor machine of oil-free air compressor machine multiple spot support crankshaft structure, this air compressor machine include two jar pistons and motor, its characterized in that, two jar pistons with the air compressor machine axis distributes for the axle offset, include in the air compressor machine: and the main shaft is connected with the motor and is driven by the motor to rotate, wherein the motor is started to provide power for the main shaft so as to drive the crankshaft to rotate, and the two cylinder pistons biased to the crank do alternate reciprocating motion.

Due to the adoption of the technical scheme, the utility model discloses compare in prior art and have following beneficial technological effect:

1. the pistons are arranged in parallel and oppositely and distributed on two sides of the axis direction of the crankshaft, so that the axial distance of the pistons is zero, and the first-order reciprocating inertia moment and the rotating inertia moment are further balanced on the basis of balancing the first-order reciprocating inertia force, the rotating inertia force and the second-order reciprocating inertia moment in the alternate reciprocating constant-speed motion of the two-cylinder piston;

2. furthermore, the distance between the two cylinder pistons is reduced, so that the problem that mutual superposition of first-order reciprocating inertia moment is difficult to balance and eliminate in the prior art by adding a balance weight on a crank is solved;

3. the first-order reciprocating inertia moment and the rotating inertia moment are balanced, so that the vibration problem in the whole operation process of the mechanism is greatly relieved, the stability of equipment operation is ensured, and the service life of the whole mechanism is ensured;

4. the first connecting rod and the second connecting rod of the two-cylinder piston can adopt different shapes or material proportions to realize the same mass and gravity center, for example, the first connecting rod is arranged to be forked from one end to one side to form a V-shaped connecting piece with two big ends, and the two big ends are butted with corresponding cranks of a crankshaft;

5. the piston connecting rod is connected with two offset-arranged cylinder pistons, and the offset two cylinder pistons are also made into the same mass by adopting different material densities, so that the first-order reciprocating inertia force and the rotating inertia force are balanced, and the vibration amplitude of the whole machine in the running state is reduced;

6. the two pistons which are oppositely arranged or arranged in an offset way can reduce the volume of the piston cylinder, so that the structure of the whole machine is more compact, the whole machine arrangement is convenient, the specification of the whole machine is reduced, and the service life of the whole machine is prolonged;

7. a lubricating oil passage which is vertical to the extending direction of the inner hole is formed in the crank, the bottom of the lubricating oil passage further extends towards the end face direction of the two cranks respectively, a plugging cover is arranged at the position of the through hole on the lubricating oil passage, and a plugging ball is arranged in the passage towards the end face direction of the crank, so that the lubricating oil passage forms a seal, and under the action of an external oil pump, pressure lubrication is provided for each bearing bush on the crank;

8. the mode of discharging gas in two cylinders after one-stage compression in the prior art is improved into a mode of discharging gas after two-stage compression, and specifically, the bottom of a low-pressure piston cylinder body is provided with an air inlet valve plate which is opened and closed towards the inner side of the cylinder body, a valve plate which is positioned at one side of a low-pressure piston is provided with an air outlet valve plate which is opened and closed towards an airflow cavity, and a valve plate which is positioned at one side of a high-pressure piston is provided with an air inlet valve plate which is opened and closed towards a high-pressure piston cylinder and an air outlet valve plate which is communicated with the air outlet cavity, so that the gas in the low-pressure piston cylinder enters the high-pressure piston cylinder through the airflow cavity after passing through the first-stage compression piston cylinder, and is discharged after flowing into the air outlet cavity from the high-pressure piston cylinder after secondary compression, and the alternating motion from a lower dead point to an upper dead point of the high-pressure piston can be realized due to the adoption of the eccentric connecting rod structure, thus the gas in each cylinder can be compressed alternately, the two-stage compressed gas obviously improves the exhaust pressure of the air compressor;

9. the cylinder head is cooled in real time through an external fan in the compression process, all parts heated due to the alternate reciprocating motion of the piston and the heat generated by the compressed gas are cooled, and the high-pressure gas subjected to secondary compression by the high-pressure piston flows back to the exhaust cavity and is then discharged, so that the exhaust temperature is effectively reduced, the operating condition of each component such as a bearing is further improved, the service life of each component is prolonged, and the operating stability of the whole machine is ensured;

10. the stroke limiting plates are respectively arranged on the exhaust valve plates, so that the stroke of the exhaust valve plates is limited by the stroke limiting plates when the exhaust valve plates are opened, and the opening angle of the exhaust valve plates is controlled, so that the piston cylinder is ensured to exhaust outwards stably, the valve plates are ensured to be closed timely, and the compression efficiency of the whole machine is ensured;

11. arranging a dustproof oil seal at the outer side of the bearing, wherein the dustproof oil seal is formed by vulcanizing a rubber piece and a supporting framework, so that the dustproof oil seal extends along the circumferential direction of the shaft surface of the maintenance-free bearing to realize the sealing between the maintenance-free bearing and the outer side of the motor spindle;

12. adopt a split type bent axle transmission structure of multiple spot support, the intensity that the guarantee multiple spot supported, this structure has effectively solved drive disk assembly simultaneously because of processing and assembly error, leads to two cranks shape and position deviation too big, causes the big, the low technical problem in life-span of operation vibration.

Drawings

FIG. 1 is a cross-sectional view of a prior art piston air compressor cylinder with a cross-sectional structure;

FIG. 2 is a schematic view of a piston rod arrangement of a piston air compressor according to a preferred embodiment of the present invention;

FIG. 3 is a side view illustrating a side structure of a piston connecting rod structure of the piston air compressor shown in FIG. 2;

FIG. 4 is a sectional view showing a sectional structure in the direction A-A of FIG. 3;

FIG. 5 is a schematic diagram illustrating the configuration of a counterweight in the piston rod arrangement of the piston air compressor shown in FIG. 2;

FIG. 6 is a state diagram illustrating the piston rod structure of the piston air compressor shown in FIG. 2 rotated 90 degrees;

FIG. 7 is a state diagram illustrating the piston rod structure of the piston air compressor shown in FIG. 2 rotated 180 degrees;

FIG. 8 is a state diagram illustrating the piston rod structure of the piston air compressor shown in FIG. 2 after 270 degrees of rotation;

fig. 9 is a schematic view showing a structure of an oil-free two-stage air compressor using a piston rod structure of a piston air compressor in accordance with still another preferred embodiment of the present invention;

fig. 10 is a plan view illustrating a top view structure of the oil-free two-stage air compressor in the preferred embodiment shown in fig. 9;

FIG. 11 is a partial cross-sectional view showing the partial cross-sectional structure of FIG. 10;

fig. 12 is a schematic view illustrating a structure of a multi-point supporting crankshaft of an oil-free air compressor according to another preferred embodiment of the present invention;

fig. 13 is a schematic view illustrating a structure in which a multi-point support crankshaft and a connecting rod are connected to the oilless air compressor shown in fig. 12.

Fig. 14 is a sectional view showing a sectional structure of a two-stage compressed air compressor according to another preferred embodiment of the present invention.

Detailed Description

The embodiments of the present invention will be described with reference to the drawings, wherein the embodiments of the present invention relate to a multi-point supporting crankshaft structure of an oil-free air compressor and an oil-free two-stage air compressor. Those of ordinary skill in the art will recognize that the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and not intended to limit the scope of the claims. Furthermore, in the present description, the drawings are not to scale and like reference numerals refer to like parts.

It should be noted that, in the embodiments of the present invention, the expressions "first" and "second" are used for distinguishing two entities with the same name but different names or different parameters, and it can be seen that "first" and "second" are only used for convenience of description and should not be understood as limitations to the embodiments of the present invention, and the following embodiments do not describe this any more.

The utility model discloses an in the preferred embodiment piston air compressor piston rod structure, to among the prior art piston air compressor machine operating condition under the vibrations big, the short suggestion of life. It is known that the main cause of vibration in piston air compressors is due to the inertia forces or moments of inertia of the unbalanced masses of the crank-link mechanism. Therefore, to eliminate or reduce the vibration of the air compressor, the first considered main method is to balance the structure of the crank link, thereby eliminating or limiting the unbalanced inertial force of the rotating parts or the reciprocating mechanism to limit the vibration within the allowable range.

The utility model discloses a preferred embodiment is through making two parallel opposition settings of cylinder piston to the distance between the two cylinder piston axial lead is reduced in the realization, in order to reach on the basis of balanced first-order reciprocal inertia force, rotatory inertia force and the reciprocal inertia moment of second order, further makes first-order reciprocal inertia moment, the reciprocal inertia force of second order and rotatory inertia moment obtain balanced technological effect.

Fig. 2 is a schematic view illustrating a piston rod structure of a piston type air compressor according to a preferred embodiment of the present invention. As shown in fig. 2, the piston rod structure of the piston air compressor according to the preferred embodiment of the present invention includes two rows of pistons and a crankshaft 10 connected to the pistons, and the two rows of pistons are respectively connected to the crankshaft 10 through connecting rods. Specifically, fig. 2 shows the connecting rod arrangement in a non-operating state, in which two rows of pistons are seen to be arranged in parallel opposition along opposite sides of the axis of the crankshaft 10.

Fig. 3 is a side view showing a side structure of a piston connecting rod structure of the piston type air compressor shown in fig. 1. Fig. 4 is a sectional view showing a sectional structure in a direction a-a of fig. 3. As can be seen from fig. 3 and 4, the crankshaft 10 is formed with a plurality of inflection points including two first cranks 11 and a second crank 12 located between the two first cranks 11, and the two pistons are respectively defined as a first piston 21 and a second piston 22 according to the direction shown in fig. 2, then the connecting rod connecting the first piston 21 and the first crank 11 is defined as a first connecting rod 31, and the connecting rod connecting the second piston 22 and the second crank 12 is defined as a second connecting rod 32, as shown in the figure, the first connecting rod 31 and the second connecting rod 32 of the two pistons can adopt different shapes or material proportions to achieve the same mass and gravity center, in the preferred embodiment, the first connecting rod 31 is "V" shaped, and the small end connected with the pistons is branched to form two large ends after extending towards the direction of the crankshaft 10 and respectively connected with the two first cranks 11 by bolts 23, and the second connecting rod 31 is long and straight, i.e. a small end connected to the second piston 22 and a large end connected to the second crank 122 via a bolt 23.

With continued reference to fig. 4, the first crank 11 and the first connecting rod 31 are respectively formed with first inner holes 13 at positions corresponding to the two large ends, and first bearing bushes 14 are disposed in the two first inner holes 13, that is, the two large ends of the first connecting rod 31 are connected to the two first cranks 11 by bolts respectively penetrating through the two first inner holes 13 to be fixed; similarly, a second inner hole 15 is formed at a position of the second crank 12 corresponding to the large end of the second connecting rod 32, a second bearing bush 16 is arranged in the second inner hole 15, and the large end of the second connecting rod 32 is connected with the second crank 12 through a bolt penetrating through the second inner hole 15 to be fixed.

With continued reference to fig. 4, two through holes 17 with opposite opening directions are formed on the end surfaces of the two first cranks 11, and a lubricating oil passage 18 perpendicular to the extending direction of the first inner hole 13 is formed in each through hole 17, which can also be said that the through holes 17 on the two first cranks 11 extend to the bottom in the direction of the other crank, and then extend in the direction of the end surface of the first crank 11 and the direction of the second crank 12 to form two long and narrow passages, and wherein the passages of the two lubricating oil passages 18 extending in the direction of the second crank 12 converge at the position of the second inner hole 15. In the lubricating oil passage 18, the position of the through hole 17 is sealed by a blocking cover 171, and a passage leading to the end face direction of the first crank 11 is sealed by a blocking ball 172, so that the lubricating oil passage 18 forms a sealed oil passage by the blocking cover 171 and the blocking ball 172, and thus, pressure lubrication is realized for the bearing bushes on the first crank shaft 11 and the second crank shaft 12 under the action of an external oil pump.

In the preferred embodiment, setting the offset distance between the first piston 21 and the second piston 22 as e, then setting the hole center distance between the large end and the small end of the first connecting rod 31, or between the large end and the small end of the second connecting rod 32 as l, and setting the crank rotation radius as r, the included angle α between the first crank 11 and the second crank 12 satisfies: cos (a/2) ═ e/(l + r). That is, by changing the size of the angle between the first crank 11 and the second crank 12, the first piston 21 and the second piston 22 can be moved toward each other at a constant speed to reduce the running vibration, and, on the basis of this, it is possible to further reduce the running vibration by adding a balance weight to the crank first crank 11 and the crank second crank 12. FIG. 5 is a schematic diagram illustrating the configuration of a counterweight in the piston rod arrangement of the piston air compressor shown in FIG. 2. The balance weight 19 is provided at the crank position of the crankshaft, and the rotational inertia force generated by the balance weight 19 is balanced with the rotational inertia force generated by the first connecting rod 31 and the second connecting rod 32 during the alternate reciprocating motion of the first connecting rod 31 and the second connecting rod 32. In other embodiments of the present invention, the same technical effects can be achieved by the way of removing the weight, in addition to the way of adding the weight.

Fig. 6 to 8 show the piston rod structure according to the preferred embodiment of the present invention rotated by 90 degrees, 180 degrees, and 270 degrees from the initial state, respectively. Referring to fig. 6 to 8, in actual conditions, the first connecting rod 31 and the second connecting rod 32 perform alternating reciprocating constant-speed motion, so that the two pistons perform corresponding alternating reciprocating constant-speed motion, and as the first connecting rod 31 is in a cross-over type, the first connecting rod 31 gives way for the motion of the second connecting rod 32 during the alternating motion.

And in the different embodiments of the utility model, except with this kind of mode of parallel opposition of piston cylinder, also can adopt the mode that two jars biasing distribute, also use the air compressor machine main shaft as the axle center, two jars use the air compressor machine main shaft to distribute as the axle center biasing, also can realize reducing the purpose of distance between two jar piston axial leads equally. Fig. 9 is a schematic view showing a structure of an oil-free two-stage air compressor using a piston rod structure of a piston air compressor according to still another preferred embodiment of the present invention. Fig. 10 is a plan view illustrating a top view structure of the oil-free two-stage air compressor in the preferred embodiment shown in fig. 9. Fig. 11 is a partial sectional view showing the partial sectional structure of fig. 10. Referring to fig. 9 to 11, the whole machine of the present invention is placed on a pair of front rubber shock absorbing pads 51 and a pair of rear rubber shock absorbing pads 52, and the two-cylinder pistons (61, 62) are distributed with the axis of the air compressor as an offset, and as an extension of the application of the above piston-connecting rod structure, the two-cylinder pistons are also made of different material density to have the same mass, so that the first-order reciprocating inertia force and the rotating inertia force reach balance, and the vibration amplitude under the running state of the whole machine is reduced. One end of the main shaft 40 is engaged with the motor 50, and the other end is engaged with the crankshaft 10, so that the main shaft 40 drives the crankshaft 10 to rotate under the driving of the motor 50, and the connecting rod connected with the crankshaft 10 performs alternating reciprocating constant-speed motion, so that the biased two-cylinder piston performs alternating reciprocating constant-speed motion, and the gas in the cylinder is compressed.

In order to ensure that the bearing can be pressed on the crank during assembly, a split crank is also adopted theoretically, but if the split crank is adopted, the performance life is poor due to the fact that the machining and the assembly are difficult to ensure the integrity and the form and position tolerance are overlarge. In order to solve the technical problem, it is corresponding, the utility model discloses an in the preferred embodiment provide an oil-free air compressor machine multiple spot support crankshaft structure. Fig. 12 is a schematic view illustrating a structure of a multi-point supporting crankshaft of an oil-free air compressor according to another preferred embodiment of the present invention. Fig. 13 is a schematic view illustrating a structure in which a multi-point support crankshaft and a connecting rod are connected to the oilless air compressor shown in fig. 12. Referring to fig. 12 and 13, the crank structure 100 is connected to the compressor connecting rod 200, the crank structure 100 is configured in three stages, for convenience of description, three stages of the crank structure are defined by its shape as a third crank 101, a fourth crank 102, and a fifth crank 103 connecting the third crank 101 and the fourth crank 102, the third crank 101 and the fourth crank 102 are oppositely disposed with respect to the fifth crank 103, as shown in the figure, a butt joint position of the third crank 101 and the fifth crank 103 forms a first eccentric journal 104, a butt joint position of the fifth crank 103 and the fourth crank 102 forms a second eccentric journal 105, and an end of the third crank 101 not connected to the fifth crank 103 and an end of the fourth crank 102 not connected to the fifth crank 103 form a main journal 106, the main journal 106 corresponds to the main shaft after assembly, a support bearing 107 may be added on the main journal 106, further, a support bearing 107 may be provided on the outer journal of the third crank 101.

In this embodiment, the third crank 101 and the fifth crank 103, and the fifth crank 103 and the fourth crank 102 are connected by forming an interference structure with the transmission positioning pin 108, and are fixed by pressing with the inner ring of the bearing. Specifically speaking, the utility model discloses a bent axle that multiple spot supported is equipped with eccentric positioning through-hole structure on its eccentric crank, and bent axle structure is accomplished two main journals, eccentric crank axle journal, the eccentric locating hole processing of crank earlier by integral bent axle, further carries out thermal treatment and surface treatment etc.. And after the finished product is qualified, cutting and separating along the central line of the crank, thereby ensuring the tolerance consistency of the two parts of the separated crank. The multi-point supported crankshaft can adopt the following steps during assembly: the maintenance-free bearing inner ring and a half crank of the third crank 101 are pressed and mounted, a transmission positioning pin shaft 108 is pressed into the eccentric positioning through hole structure in the crank in an interference mode for positioning, and then a half crank of the fifth crank 103 is pressed into the crank. Thereafter, the other half of the fifth crank 103 is assembled with the half of the fourth crank 102 accordingly. In addition, optionally, the transmission positioning pin 108 is flanged and riveted to ensure the integral strength and prevent the separation. The structure process can guarantee the coaxiality of the two separated half crankshaft cranks after press mounting and the coaxiality of the positioning pin shaft, and then can guarantee the coaxiality of the two fulcrum shaft diameters after assembly, so that the transmission operation is stable. In addition, preferably, the maintenance-free bearing of the structural process adopts a maintenance-free double-row maintenance-free bearing, so that two roller bearing raceways in the maintenance-free bearing are uniformly distributed at two ends of two separated half cranks, and the stress balance strength of the crankshaft is reliable.

In practical application, although two rows of pistons can alternately reciprocate at a constant speed, the technical problems that exhaust pressure is insufficient due to insufficient gas compression and exhaust temperature is overhigh due to overheating of equipment are still solved, and the long-term existence of the factors can further cause additional load on components such as a bearing and the like in the motion process of the piston, even influence the service life of the components and the running stability of the whole machine.

In view of the above problem, it is conceivable to increase the exhaust pressure by further compressing the gas, and to decrease the exhaust temperature by lowering the temperature or conducting the gas. Therefore, in the embodiment of the present invention, a two-stage compressed air compressor using the aforementioned crankshaft structure is further provided. Fig. 14 is a sectional view showing a sectional structure of a two-stage compressed air compressor according to another preferred embodiment of the present invention. As shown in fig. 10, 11 and 14, the two-stage compression air compressor in the preferred embodiment includes an offset two-cylinder piston, which is defined as a low pressure piston 61 and a high pressure piston 62, respectively, the high pressure piston 62 and the low pressure piston 61 are fixed to a housing 64 by a tightening sleeve 63 and a plurality of bolts, the high pressure piston 62 and the low pressure piston 61 are connected to an eccentric link 66 by a roller bearing 65, and a maintenance-free bearing 67 is provided at the position where the high pressure piston and the low pressure piston are connected to a crankshaft, on the motor spindle 40, and outside the motor spindle 40, and a dust-proof oil seal 68 is provided outside the maintenance-free bearing 67.

The top of the two-cylinder piston is provided with a valve plate 69 covering the two-cylinder piston, the valve plate 69 is fixed by a cylinder cover 70, and the cylinder cover 70 is provided with a discharge port 71. The valve plate 69 is spaced from the top cover of the air compressor housing 64 to define a cavity area between the valve plate 69 and the top cover of the air compressor housing 64, which is defined as the air flow chamber 72.

The high pressure piston 62 and the low pressure piston 61 are respectively connected to an eccentric connecting rod 66 through a piston pin 85, and the crankshaft 10 is connected to the eccentric connecting rod 66 and the motor spindle 40, so that the eccentric connecting rod 66 is driven by the crankshaft 10 to alternately rotate and reciprocate when the motor spindle 40 rotates, so that the low pressure piston 61 and the high pressure piston 62 alternately reciprocate between respective top dead center and bottom dead center.

The gas is drawn into the housing 64 from the inlet connector 73 of the air compressor, enters the housing 64 through a plurality of muffling holes 74 in the housing 64, and is discharged to the low pressure piston 61. Referring to fig. 12, a first intake valve sheet 75 is disposed at the bottom of the cylinder of the low pressure piston 61, the first intake valve sheet 75 can be fixedly connected to the bottom of the cylinder of the low pressure piston 61 in an opening and closing manner, and in a non-pressure-bearing state, the first intake valve sheet 75 is attached to the bottom of the cylinder of the low pressure piston 61, that is, at this time, the cylinder of the low pressure piston 61 is sealed by the first intake valve sheet 75.

With continued reference to fig. 12, the valve plate 69 is formed with three through holes, one of which for exhaust is located on the valve plate 69 on the side of the low pressure piston 61, defining a first exhaust port 76; the remaining two through-holes are formed in the valve plate 69 on the side of the high-pressure piston 62 and are defined as a second exhaust port 77 and a third exhaust port 78, respectively, and as seen from the drawing, the first exhaust port 76, the second exhaust port 77 and the third exhaust port 78 are disposed so as to communicate the piston cylinder and the air flow chamber, respectively. A first exhaust valve plate 79 is fixed on the first exhaust port 76 in a covering manner, and the first exhaust valve plate 79 can be opened and closed towards one side of the airflow cavity 72; a second air inlet valve plate 80 is fixed on the second air outlet 77 in a covering manner, and the second air inlet valve plate 80 is positioned at the bottom of the valve plate 69 and can be opened towards one side of the cylinder body of the high-pressure piston 62; the third exhaust port 78 is covered and fixed with a second exhaust valve plate 81, and the second exhaust valve plate 81 is located on the top of the valve plate 69 and can be opened toward the airflow chamber 72 side. Similar to the first intake valve sheet 75, in an unpressurized state, the first exhaust valve sheet 79 covers the top of the low-pressure piston 61 to seal between the low-pressure piston 61 and the airflow chamber 72, the second intake valve sheet 80 covers the bottom of the valve plate 69 to seal between the airflow chamber 72 and the cylinder of the high-pressure piston 62, and the second exhaust valve sheet 81 covers the top of the valve plate 69 to seal between the airflow chamber 72 and the cylinder of the high-pressure piston 62.

In order to limit the opening angle of each exhaust valve plate, a stroke limiting plate 82 may be disposed on the first exhaust valve plate 79 and the second exhaust valve plate 81, and the stroke limiting plate 82 is also disposed above the valve plate 69 and is inclined. One end of the stroke limiting plate 82 is fixed to the valve plate 69, and the other end thereof extends in an oblique direction above the exhaust valve plate, so that an area formed between the plate surface of the stroke limiting plate 82 and the surface of the exhaust valve plate is an opening area of the exhaust valve plate. The first exhaust valve plate 79 and the second exhaust valve plate 81 are turned over towards the direction of the airflow cavity 72 and limited by the stroke limiting plate 82 above the first exhaust valve plate and the second exhaust valve plate, so that stable exhaust of the piston cylinder to the airflow cavity is guaranteed, timely closing of the valve plates is guaranteed, and compression efficiency of the whole machine is guaranteed. Further, a self-lubricating piston ring 83 and a guide ring 84 are provided on both the high-pressure piston 62 and the low-pressure piston 61.

When the reciprocating engine works, the high-pressure piston 62 and the low-pressure piston 61 are driven by the crankshaft connecting rod mechanism to alternately reciprocate up and down. When the low-pressure piston 61 moves from the bottom dead center to the top dead center, the volume in the cylinder increases to generate negative pressure, and gas pushes away the first air inlet valve plate 75 from the lower part of the low-pressure piston 61 and is sucked into the airflow cavity 72; when the low-pressure piston 61 moves from the bottom dead center to the top dead center, the volume in the cylinder is reduced, the gas is extruded, the gas pressure is increased until the first exhaust valve plate 79 is pushed to be discharged into the gas flow chamber 72, and at this time, the primary compression of the gas in the first-stage cylinder is completed. Meanwhile, the high-pressure piston 62 moves from the top dead center to the bottom dead center, at this time, the volume in the cylinder increases to generate negative pressure, and under the combined action of the force of the primary compressed gas, the gas compressed by the primary compressed gas in the airflow cavity 72 is sucked into the cylinder from the opening of the second air inlet valve plate 80; when the high pressure piston 62 moves from the bottom dead center to the top dead center, the volume in the cylinder decreases, the gas is squeezed again, the gas pressure increases until the second exhaust valve plate 81 is pushed to exhaust into the gas flow chamber 72 again, and the second compression of the gas is completed at this time. The above process repeats as the piston reciprocates, with the gas being continually compressed and eventually expelled through the discharge port 71.

8. the mode of discharging gas in two cylinders after one-stage compression in the prior art is improved into a mode of discharging gas after two-stage compression, and specifically, the bottom of a low-pressure piston cylinder body is provided with an air inlet valve plate which is opened and closed towards the inner side of the cylinder body, a valve plate which is positioned at one side of a low-pressure piston is provided with an air outlet valve plate which is opened and closed towards an airflow cavity, and a valve plate which is positioned at one side of a high-pressure piston is provided with an air inlet valve plate which is opened and closed towards a high-pressure piston cylinder and an air outlet valve plate which is communicated with the air outlet cavity, so that the gas in the low-pressure piston cylinder enters the high-pressure piston cylinder through the airflow cavity after passing through the first-stage compression piston cylinder, and is discharged after flowing back to the air outlet cavity from the high-pressure piston cylinder after secondary compression, and the alternate movement of the low-pressure piston from a bottom dead point to the top dead point can be realized due to the adoption of the eccentric connecting rod structure, namely, the gas in the cylinders can be alternately compressed, thereby, the two-stage compressed gas obviously improves the exhaust pressure of the air compressor;

9. the cylinder head is cooled in real time through an external fan in the compression process, all parts heated due to friction of alternate reciprocating motion of the piston and heat generated by compressed gas are cooled, and high-pressure gas subjected to secondary compression of the high-pressure piston flows back to the exhaust cavity and then is exhausted, so that the exhaust temperature is effectively reduced, further, the operation working conditions of components such as a bearing and the like are improved, the service life of each component is prolonged, and the operation stability of the whole machine is ensured;

10. the stroke limiting plates are respectively arranged on the exhaust valve plates, so that when the exhaust valve plates are opened towards the airflow cavity, the stroke of the exhaust valve plates is limited by the stroke limiting plates, and the opening angle of the exhaust valve plates is controlled, so that the piston cylinder is ensured to exhaust outwards stably, close back in time, reduce leakage, and ensure compression efficiency;

The above description of the present invention is provided to help understand the method and the core idea of the present invention, and the purpose of the present invention is to allow people familiar with the art to understand the contents of the present invention and to implement the method, and thus the protection scope of the present invention cannot be limited by the above description. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.

Claims

1. A multi-point supporting crankshaft structure of an oil-free air compressor is connected with a connecting rod of the air compressor and is characterized in that the crankshaft structure is in a three-section type and comprises a first crank, a second crank and a third crank, wherein the first crank and the second crank are symmetrical, the third crank is connected with the first crank and the second crank,

the first crank, the second crank and the third crank are oppositely distributed, so that a first eccentric journal is formed at the butt joint position of the first crank and the third crank, a second eccentric journal is formed at the butt joint position of the third crank and the second crank, and interference structures are formed between the first crank and the third crank and between the third crank and the second crank and a transmission positioning pin shaft.

2. An oil-free air compressor multipoint support crankshaft structure as claimed in claim 1, wherein the first crank and the third crank, and the third crank and the second crank are pressed and fixed with the inner ring of the maintenance-free bearing.

3. An oil-free air compressor multipoint support crank shaft structure as claimed in claim 2, wherein an end of the first crank not connected with the third crank, and an end of the second crank not connected with the third crank, are formed with main journals, wherein,

and supporting bearings are arranged on the journal of the two main journals and the journal of the third crank.

4. An oil-free air compressor multipoint support crankshaft structure as claimed in claim 2, wherein the maintenance-free bearing is a maintenance-free double-row bearing, and two roller bearing raceways therein are uniformly distributed at two ends of the first crank, the second crank and the third crank.

5. An oil-free air compressor multipoint support crankshaft structure as claimed in any one of claims 1 to 4, wherein the first crank, the second crank and the third crank are fixed with the transmission positioning pin shaft by flanging and riveting.

6. An oil-free two-stage air compressor which is based on the oil-free two-stage air compressor of any one of claims 1 to 5 and has a multi-point supporting crankshaft structure, the air compressor comprising a two-cylinder piston and a motor, characterized in that the two-cylinder piston is distributed with the axis of the air compressor as an offset, the air compressor further comprising:

a main shaft connected to the motor and driven to rotate by the motor, wherein,

and when the motor is started to provide power for the main shaft so as to drive the crankshaft to rotate, the two-cylinder piston biased to the air compressor performs alternate reciprocating motion.