CN100465449C

CN100465449C - Multi-cylinder rotary compressor

Info

Publication number: CN100465449C
Application number: CNB011456574A
Authority: CN
Inventors: 竹林昌宽; 吉村保广; 关上和夫; 野崎务; 远藤喜重; 早濑功
Original assignee: Hitachi Appliances Inc
Current assignee: Hitachi Johnson Controls Air Conditioning Inc
Priority date: 2000-10-30
Filing date: 2001-10-30
Publication date: 2009-03-04
Anticipated expiration: 2021-10-30
Also published as: MY124954A; MY141515A; CN1356476A; KR20020034883A; KR100432115B1

Abstract

A multi-cylinder rotary type compressor, where an electromotor part and a compressor part are set up in the closed container, and the electromotor part and the compressor part are connecting by the crankshaft, the crankshaft has a first crank pin and second crank pin relatively to the rotation axis eccentricly. The compressor includes the main bearing and auxiliary axis supporting crankshaft; a first and second cylinder seperated by a clapboard, mounted between the main bearing and auxiliary axis and having a through hole with an inside diameter larger than the outside diameter of the first or second crank pin; and a first and second piston making eccentric motion along the rotation of the crankshaft in the first and second cylinder; the diameter of the crankshaft formed between two compression chamber of the first and second cylinder larger than the diameter of the crankshaft inserted on the rotor of the electromotor part.

Description

Multi-cylinder rotary air compressor

Technical field

The present invention relates to employed multi-cylinder rotary air compressor in a kind of freeze cycle of for example refrigerator or air conditioner etc., particularly can reduce the bending deflection of bent axle, the multi-cylinder rotary air compressor of raising the efficiency.

Background technique

As the compressor that air conditioner or refrigerator are used, use compressors such as reciprocating type, rotary, eddy type and screw type.This class compressor in the past uses the HCFC series coolant.But, now, people understand, because the HCFC series coolant also can decompose because of the solar ultraviolet irradiation, the chlorion of generation can destroy the ozonosphere in the atmosphere, therefore, down leading in united nations environment programme division, concluded " about the Montreal Protocol of the material that damages the ozone layer " in 1987,, limited the HCFC series coolant interimly since 2004.For the above-mentioned reasons, each company competitively develops use as the HFC series coolant of the alternative refrigerant of HCFC series coolant or divide in the subconstiuent the not compressor of the natural series coolant in fluorine-containing Lyons.

In compressor, use the occasion of the natural refrigeration agent of HFC refrigeration agent or carbon dioxide etc., because the pressure height of working gas, will be from the leakage of the refrigerant gas in pressing chamber slide part gap more than HCFC series coolant in the past.Therefore, there is being utilization can set the situation of the rotary compressor of little clearance leakage aspect the compressor that uses alternative refrigerant.

Because of air pressure is higher than the other problem that air pressure in the past brings be, remaining on the pressing chamber exhaust port refrigerant gas in the existing dead volume can't be discharged from and reexpand, reduced volumetric efficiency, this problem can't be solved owing to be restricted on the structure.In this occasion, at the compressor more than 2～3 horsepowers, the problem of above-mentioned leakage or dead volume is more outstanding for output power.So, in using the compressor of alternative refrigerant, use the leakage that can dwindle the gap little and to set the situation of rotary compressor of structure of dead volume of pressing chamber a lot of lessly.

But, the occasion of use alternative refrigerant in single cylinder rotary compressor, because the difference of the suction pressure of working gas and head pressure is bigger, along with compression moment of torsion amplitude of fluctuation is big, so the eccentric part whirling vibration meeting of bent axle increases.Particularly output power more can be brought the big problem of vibration change etc. in the occasion of the compressor of 2～3 horsepowers of degree.In order to address this is that, adopted multi-cylinder rotary air compressor.

On the one hand, when design general (for example use R22 refrigeration agent in the past etc.) rotary compressor, the mechanical loss of the rotating power that causes with the friction that reduces the bent axle (running shaft) that produces in bearing portion and bearing, be that frictional loss is a purpose, and in order to dwindle the area of contact of bent axle and bearing, further reduce moment of inertia, expectation is designed to minimum as much as possible with the diameter of axle of bent axle.In addition, the weight by the piston solid of rotation that reduces the bent axle diameter, can alleviate to constitute together with bent axle reduces the electric power that drive motor consumes.And, further reducing the bent axle diameter, external diameter that also can compresses machine integral body is to little spatialization advantageous particularly.

On the other hand, will be as an alternative the HFC series coolant of the high condensing pressure of refrigeration agent be used in the occasion of compressor, compare with HCFC refrigeration agent in the past, because latent heat of vaporization is big, boil-off gas density is big, it is big that the ability of the average discharge volume of compressor (unit discharge volume) becomes.For example, by refrigeration agent is changed to R410A from R22, compression pressure approximately becomes 1.5 times.

As the double cylinder rotary compressor that is of a size of motion with the pressing chamber that adopts above-mentioned alternative refrigerant, be documented in the spy and open in the flat 8-144976 communique, the resulting value of internal diameter of height, cylinder of removing cylinder with the offset of bent axle is in 0.07～0.13 scope.

As above-mentioned, the multi-cylinder rotary air compressor that uses constituting component in the past to make, the occasion at the alternative refrigerant that uses HFC series coolant or natural refrigeration agent etc. has following lime light.

I) there are the suction pressure of working gas and the pressure difference of head pressure to become big refrigeration agent.

Ii) owing to adopt multi cylinder, the interval of the bearing interval each other that is arranged on the cylinder both sides during than single cylinder is big.The fulcrum that promptly bears gas load is elongated.

Be intention iii) to design little bent axle diameter.

When above-mentioned each lime light of self-criticism, the bending deflection that is configured in the bent axle between the bearing of a plurality of cylinders both sides is easy to become big.In case it is big that the bending deflection of bent axle becomes, the inclination of the bearing that bent axle is relative will become greatly, can produce incomplete contact.Because not exclusively contact, bent axle will bear the extruding counter-force from bearing.The energy loss that causes based on the friction of this counter-force can become the driving force loss.

Further, between two bearings, because bending deflection is caused that by bent axle piston also can tilt.Therefore, produce not exclusively contact between the end face (opposing side of cylinder) of end face of the parts of airtight each cylinder (the cylinder opposing side of hermetic unit) and dividing plate and each piston end surface.Each piston end surface bears the counter-force from opposing end surface, produces frictional loss, has further enlarged the loss of driving force.In addition, the outside of piston produces with the inside of cylinder and not exclusively contacts, and piston bears the frictional loss that produces from the counter-force of cylinder the inside and also can take place.

As above-mentioned, when the bending deformation quantity of bent axle increased, the energy loss (frictional loss) that friction causes was most important to the performance of compressor.This frictional loss is all produced by incomplete contact.Although bent axle is wanted bending, pass through upper and lower end face (opposing side of cylinder) constraint by the hermetic unit of 2 bearings or dividing plate and cylinder, on bent axle, can produce counter-force.Because the area of contact of contacting part separately is little, interface pressure is high,, will cause the mechanical energy losses of compressor therefore along with the rotation of bent axle.

In addition, because the frictional loss mean effort that bearing portion produces is on bent axle and bearing, the therefore above-mentioned frictional loss that bending deflection produced is little.Thereby the diameter of bent axle is little, has reduced the frictional loss between bent axle and bearing, and performance is had certain effect.But owing to the big frictional loss that increases of distortion change of bent axle is big to the influence change of compressor performance, so dwindling of bent axle diameter is limited.

Consider generation, be necessary inclination according to piston because of the tilting of the piston that bending brought of bent axle, with the gap between piston end surface and dividing plate and the end plate (hermetic unit) set bigger.In addition, also must consider gap between the blade of piston and differentiation pressing chamber that contacts with this piston and suction chamber.Because of the increase in these gaps, the leakage rate of pressurized gas increases, and the volumetric efficiency of pressing chamber descends.

On the other hand, refrigeration agent is that mix refrigerant or carbon containing are the occasion of nature refrigeration agent using the not high HFC of working pressure as an alternative, in case the distance between bearing increases, will produce above-mentioned deflection of crankshaft, make tilting of the piston thus, produce on bearing and the end plate face and not exclusively contact.Do not have the inhibiting chlorine molecule of high pressure because alternative refrigerant does not resemble in the past the HCFC series coolant, therefore increase frictional loss, simultaneously, increased energy loss or abrasion yet in contacting part branch.

For addressing the above problem, use the multi-cylinder rotary air compressor of alternative refrigerant to become the problem that faces in people's design.

The technology of putting down in writing in the Te Kaiping 8-144976 communique has disclosed the design basis for the discharge efficient of obtaining optimal refrigerant gas.But record is not because of the relevant issues of the frictional loss that bending deflection produced or the volumetric efficiency reduction of bent axle.Therefore head it off also becomes important problem.

Summary of the invention

The purpose of this invention is to provide a kind of multi-cylinder rotary air compressor that bending deflection, life-span are long and compression efficiency is high that can reduce bent axle.

Another object of the present invention provides a kind of multi-cylinder rotary air compressor that can keep assembling performance and reduce the deflection of crankshaft distortion.

In order to finish above-mentioned purpose, multi-cylinder rotary air compressor of the present invention, in seal container, be provided with motor part and compressor section, motor part and compressor section link together by bent axle, bent axle has with respect to first crank pin of rotating shaft eccentric and second crank pin, and compressor section comprises main bearing and the supplementary bearing of supporting bent axle; Be arranged between main bearing and the supplementary bearing, by having first, second cylinder that the dividing plate of internal diameter greater than the through hole of the first or second crank pin external diameter separates; And first, second piston of in first, second cylinder, making eccentric motion along with the rotation of bent axle, the diameter of the bent axle between two pressing chambers that form in first cylinder and second cylinder is greater than the diameter of the epitrochanterian bent axle that is inlaid in motor part.

In addition, in order to finish above-mentioned purpose, multi-cylinder rotary air compressor of the present invention, in seal container, be provided with motor part and compressor section, motor part and compressor section link together by bent axle, bent axle has with respect to first crank pin of rotating shaft eccentric and second crank pin, is provided with jack shaft between first crank pin and second crank pin, and compressor section comprises: main bearing and the supplementary bearing of supporting bent axle; Be arranged between main bearing and the supplementary bearing, by having first, second cylinder that the dividing plate of internal diameter greater than the through hole of the first or second crank pin external diameter separates; And first, second piston of in first, second cylinder, making eccentric motion along with the rotation of bent axle, on the jack shaft of bent axle, be respectively arranged with the protuberance that the eccentric direction to crank pin stretches out.Each protuberance preferably and each crank pin be one.

The rotating locus of protuberance most outer diameter that is arranged on this bent axle intermediate portion is preferably less than dividing plate through hole internal diameter.

Moreover, in order to finish above-mentioned purpose, multi-cylinder rotary air compressor of the present invention, in seal container, be provided with motor part and compressor section, motor part and compressor section link together by bent axle, bent axle has with respect to first crank pin of rotating shaft eccentric and second crank pin, is provided with jack shaft between first crank pin and second crank pin, and compressor section comprises: main bearing and the supplementary bearing of supporting bent axle; Be arranged between main bearing and the supplementary bearing, by having first, second cylinder that the dividing plate of internal diameter greater than the through hole of the first or second crank pin external diameter separates; And first, second piston of in first, second cylinder, making eccentric motion along with the rotation of bent axle, the structure of the diametric section of jack shaft of bent axle is: greater than the lap of first crank pin and the second crank pin diameter direction section, and be provided with step between the first crank pin side of jack shaft and the second crank pin side.

That is, the area of jack shaft forms in axial two sections different modes, and simultaneously, each jack shaft forms in the mode towards the cylinder eccentric direction enlarged areas of off-centre setting.

Therefore, can be set at maximum value to the jack shaft diameter between crank pin and the crank pin, can dwindle the bending deflection of jack shaft, the interior piston lower end of piston upper end and top coffer, second cylinder of reducing in bent axle and bearing, first cylinder contacts with the incomplete of cylinder surfaces with bottom coffer, outer surface of piston, thereby, reduce frictional loss, dwindled the loss of mechanical efficiency.Further,, therefore, can reduce leakage, suppress the reduction of volumetric efficiency owing to dwindled the unnecessary gap of bent axle and bearing, piston and blade, piston and coffer.As a result, can suppress the decreased performance that crankshaft deformation causes.

In order to finish a further object of the present invention, multi-cylinder rotary air compressor of the present invention, in seal container, be provided with motor part and compressor section, motor part and compressor section link together by bent axle, bent axle has with respect to first crank pin of rotating shaft eccentric and second crank pin, and compressor section comprises: main bearing and the supplementary bearing of supporting bent axle; Be arranged between main bearing and the supplementary bearing, by having first, second cylinder that the dividing plate of internal diameter greater than the through hole of the first or second crank pin external diameter separates; And first, second piston of in first, second cylinder, making eccentric motion along with the rotation of bent axle, bent axle is provided with respectively the protuberance that the eccentric direction to crank pin stretches out connecting intermediate portion between first and second crank pin, and the face that this crank pin of the protuberance that the thickness of dividing plate and a crank pin side form is opposite and the distance of face-off between the reference line of the face of aforementioned barriers of another crank pin are compared more thinner.

Concerning the those of skill in the art in present technique field, other advantage of the present invention can be clearer by reading the best and distortion form of implementation of describing in detail below.

Description of drawings

Below, describing the present invention with reference to the accompanying drawings, these accompanying drawings just for the best of the present invention and distortion form of implementation are described, do not constitute limitation of the invention.Wherein:

Fig. 1 is the compressor section of double cylinder rotary compressor of expression the present invention first form of implementation and the profile diagram of motor part.

Fig. 2 is a schematic representation of extracting the part of bent axle 3 from Fig. 1 double cylinder rotary compressor out.

Fig. 3 is that the joint 31 with the jack shaft 30 of bent axle among Fig. 23 projects to the sectional view on the plane vertical with running shaft.

Fig. 4 is the schematic representation of extracting the part of bent axle 3 from double cylinder rotary compressor out of first modified example of expression example shown in Figure 2.

Fig. 5 is that the joint 310 with the jack shaft 300 of the bent axle among Fig. 43 projects to the sectional view on the plane vertical with running shaft.

Fig. 6 is that expression is the schematic representation of extracting the part of bent axle 3 from double cylinder rotary compressor out of second modified example of example shown in Figure 2.

Fig. 7 is that the joint with first joint 311 of the jack shaft 300 of the bent axle among Fig. 63 and second joint 312 projects to the sectional view on the plane vertical with running shaft.

Fig. 8 is the profile diagram of the rotor of the compressor section of double cylinder rotary compressor of expression the present invention second form of implementation and motor part.

Fig. 9 is the schematic representation of the part of the expression bent axle 3 of extracting the double cylinder rotary compressor among Fig. 8 out.

Figure 10 is that jack shaft 112a, the 112b with the bent axle 3 of Fig. 9 projects to the sectional view on the plane vertical with running shaft.

Figure 11 is the diagram of a part of bent axle 3 of extraction double cylinder rotary compressor of first variation of expression example shown in Figure 8.

Figure 12 is the diagram of a part of bent axle 3 of extraction double cylinder rotary compressor of second variation of expression example shown in Figure 8.

Figure 13 is that jack shaft 112a, the 112b with the bent axle 3 of Figure 12 projects to the sectional view on the plane vertical with running shaft.

Figure 14 is the diagram of a part of bent axle 3 of extraction double cylinder rotary compressor of the 3rd variation of expression example shown in Figure 8.

Figure 15 is the diagram of a part of bent axle 3 of extraction double cylinder rotary compressor of the 4th variation of expression example shown in Figure 8.

Figure 16 is the diagram of a part of bent axle 3 of extraction double cylinder rotary compressor of the 5th variation of expression example shown in Figure 8.

Figure 17 is the diagram of a part of bent axle 3 of extraction double cylinder rotary compressor of first remodeling of the 5th variation of expression example shown in Figure 8 shown in Figure 16.

Figure 18 is the diagram of a part of bent axle 3 of extraction double cylinder rotary compressor of second remodeling of the 5th variation of example shown in Figure 8 shown in Figure 16.

Figure 19 is the schematic representation of an example of expression Computer simulation results.

Figure 20 is that the expression bent axle has produced the displacement B of the crankshaft main bearing upper end portion under the diastrophic state and the graph of a relation of the minimum value C that sets the gap.

Figure 21 is the schematic representation of concluding Computer simulation results.

Figure 22 is the schematic representation that the compressor assembling operation of an embodiment of the present invention is adopted in expression.

The working of an invention form

Below, form of implementation of the present invention is described with reference to the accompanying drawings.Fig. 1 is the profile diagram of expression multi-cylinder rotary air compressor one form of implementation of the present invention, and Fig. 2 is the profile of the shape of multi-cylinder rotary air compressor bent axle, and Fig. 3 is the sectional view of bent axle section configuration in the presentation graphs 2.

In Fig. 1 to Fig. 3, show the double cylinder rotary compressor and the constituting component thereof that have two cylinders of motor portion 2 and compression mechanical part 5 in the inside of seal container 1.

Support the main bearing 4 of bent axle 3 to be fixed on the inwall of seal container 1 by welding etc.In a side space of this main bearing 4, accommodate motor 2, in the opposing party space, accommodate compression mechanical part 5.Motor 2 has the rotor 2a and relative and coaxial with it stator 2b that is inlaying bent axle 3.Stator 2b is fixed on the seal container 1.

Bent axle 3 passes main bearing 4, and its point is being supported by supplementary bearing 8.Between main bearing 4 and supplementary bearing 8, be provided with 2

cylinder

6a, 6b and dividing plate 50.By means of dividing plate 50 2

cylinder

6a, 6b are separated 2 groups of pressing chambers of formation.That is, dividing plate 50 is in and is clipped in 2 positions between cylinder 6a, the 6b.

Position in this

cylinder

6a, 6b is provided with

crank pin

13,14 on bent axle 3.In addition, in

cylinder

6a, 6b, accommodate separately

piston

10a, 10b respectively.Embed respectively among piston 10a, the

10b crank pin

13,14 is arranged.When driving bent axle 3 by motor part 2 rotations,

crank pin

13,14 rotates prejudicially, and thereupon,

piston

10a, 10b are with mutual 180 ° phase difference rotation.

These

blades

12a, 12b are crimped among this piston 10a, the 10b with spring members all the time.In cylinder 6a, form pressing chamber by piston 10a and blade 12a; In addition, in cylinder 6b, form pressing chamber by piston 10b and blade 12b.Based on the rotation of bent axle 3,

piston

10a, 10b rotate prejudicially, and thus, the pressing chamber in cylinder 6a, the 6b enlarges repeatedly or dwindles.When the pressing chamber of

cylinder

6a, 6b enlarged, the refrigerant gas of supplying with from

suction pipe

19a, 19b was drawn into pressing chamber.And, dwindle compression refrigerant gas by pressing chamber in bent axle 3 rotation.When the pressure of refrigerant gas became a certain size (head pressure), the compression refrigerant gas in the cylinder 6a was discharged in the discharge chamber 17 that is formed by main bearing 4 and Qi Gai 11.Similarly, the compression refrigerant gas in the cylinder 6b is discharged in the discharge chamber 15 that is formed by supplementary bearing 8 and Qi Gai 9.Though it is not shown in the figures,, turn back to refrigerant gas in the compressor by the mutual compression of

cylinder

6a, 6b by freeze cycle, be discharged to freeze cycle through discharge tube 18 from seal container 1.

Fig. 2 is the schematic representation of the part of the bent axle 3 extracted out from the double cylinder rotary compressor of an embodiment of the present invention.Jack shaft 30 first crank pin 13 that relative rotation axi is eccentric mutually is connected with second crank pin 14.Can see the part of bent axle 3.Through hole 51 is for being arranged on the opening portion on the dividing plate 50.First and second joint 31,32 is the part of jack shaft 30, is separately positioned on the position in the through hole 51 that is contained in dividing plate 50.The bent axle 30 usefulness casting methods that comprise first crank pin 13, second crank pin 14, jack shaft 30, first joint 32 and second joint 31 form.

By rotatablely moving during compressed refrigerant of the first piston 10a and the second piston 10b, this compressive load (not shown) acts on first crank pin 13 and second crank pin 14.The direction of this compressive load is the eccentric direction of crank pin separately.That is, effect has the tilt torque that makes bent axle 3 direction (counterclockwise) rotation left in Fig. 2.Its size is for acting on compression pressure sum on two crank pins, according to the rotational position of bent axle 3 big variation do not take place.And as described later in detail, when the pressure of the working room that is formed by the internal face of the outer wall of a piston 10 and cylinder 6 became head pressure, the size of this tilt torque was a maximum value.

Owing to there is the compressive load of this crank pin, therefore, be applied with the stress that acts on the direction of compression jack shaft 30 in the eccentric part side of jack shaft 30, perhaps in the anti-eccentric part side of jack shaft 30, be applied with towards the stress that pulls away the directive effect of jack shaft 30.Therefore, with the jack shaft in the past of bent axle 3 diameter same diameter, because of this stress makes middle axial region distortion, the incomplete problem that contacts of main bearing 4 and supplementary bearing 8 has appearred.

In order to address the above problem, in form of implementation shown in Figure 2, on the jack shaft 30 identical, be provided with the joint (is the protuberance that the center increases the diameter of jack shaft 30 with the eccentric direction) that on the eccentric direction of each crank pin, enlarges with bent axle 3 diameters cardinal principle.That is, the jack shaft 30 that is connected with first crank pin 13 is provided with first joint 32 that enlarges along the eccentric direction of crank pin 13, and the jack shaft 30 that is connected with second crank pin 14 is provided with second joint 31 that enlarges along the eccentric direction of crank pin 14.

Thus, second joint 31 that is arranged on the jack shaft 30 enlarges to the eccentric direction of crank pin 14.That is, the vertical section with respect to bent axle 3 of formed second joint 31 on the jack shaft 30 (for example AA section) expands in the section that is included in second crank pin 14 but is not included in part in the section of first crank pin 13; Similarly, first joint 32 that is arranged on the jack shaft 30 enlarges at the eccentric direction of crank pin 13.That is, the vertical section with respect to bent axle 3 of formed first joint 32 on the jack shaft 30 expands in the section that is included in first crank pin 13 but is not included in part in the section of second crank pin 14.

So by being provided with from the joint 31 and 32 of the enlarged-diameter of bent axle 3 at jack shaft 30, in Fig. 2, crank pin can support the load that is applied on the jack shaft 30, has relaxed the distortion of jack shaft 30, has suppressed the incomplete contact of each bearing.

Secondly, assembling method is described simply.In Fig. 1, motor part 2 and main bearing 4 have been assembled in the seal container 1.Below, the situation of assembling each parts that is used to form compression mechanical part 5 on the bent axle 3 that comprises first crank pin 13, second crank pin 14, jack shaft 30, first joint 32 and second joint 31 is described.

Assembling first piston 10a on first crank pin 13, configuration covers the first cylinder 6a around it.Configuration dividing plate 50.Bent axle 3 is inserted in the through hole 51 of dividing plate 50, and second crank pin 14 is passed through.The internal diameter of this through hole 51 forms with the form of the external diameter that is a bit larger tham second crank pin 14.Like this, when dividing plate 50 passes through second crank pin 14, dividing plate 50 is moved to the direction opposite with the eccentric direction of second crank pin 14.That is, dividing plate 50 moves to the center of the through hole 51 of dividing plate 50 direction consistent with the center of bent axle 3.Then, the chimeric second piston 10b on second crank pin 14 disposes second cylinder around it, is screwed supplementary bearing 8 is installed, and finishes the assembling of compression mechanical part 5.

The lime light relevant with this assembling below is shown.At first be, the first, the through hole 51 of dividing plate 50 will have the diameter that second crank pin 14 is passed.The second, be arranged on each joint on the jack shaft 30, even under the situation of bent axle 3 rotations, also do not contact with the inwall of through hole 51.Because jack shaft 30 is configured in the internal diameter of through hole 51, therefore, the inwall that is arranged on each joint on the jack shaft 30 and through hole 51 can become load when interfering.The relation of the size of the axle on the jack shaft 30 of the three, the first joint 32 and second joint 31 and the thickness of dividing plate 50 is to assemble the relation of dividing plate 50 at given location.Promptly be that during assembling, after can having passed through dividing plate 50 by second crank pin 14 of dividing plate 50 (near the jack shaft 30), dividing plate 50 can be so that the relation that the center of through hole 51 mode consistent with the center of bent axle 3 moves.

About first point, the internal diameter by making through hole 51 solves greater than the measure of the external diameter of second crank pin 14.In multi-cylinder rotary air compressor, be the airtight key element that separates pressing chamber between piston end face (being planar annular on the axle direction) and the dividing plate end face.The distance of the track of the piston external diameter of eccentric motion and dividing plate through hole internal diameter is big more, and seal is high more, therefore, wishes that the internal diameter of this through hole is little.On the other hand, in order to be assembled into dividing plate between crank pin, the through hole internal diameter of dividing plate must still, be wished the inferior limit of its difference for crank pin is passed through greater than the external diameter of at least one crank pin.

As for second point, illustrate with Fig. 3.This figure is the AA sectional view of section configuration of the joint 31 of bent axle 3 in the presentation graphs 2.Among Fig. 3, RP2 is that the center line with second crank pin 14 (solid line) is the outer radius at center, and RH is the inside radius of the through hole 51 (dotted line) of dividing plate 50.RJ is expression has second joint 31 of ultimate range apart from the center of bent axle 3 when bent axle 3 rotates the outer radius of circle (double dot dash line is at the circle of 1 position) of track, less than RH.In addition, the circle of double dot dash line portion 2 positions is crank pin 13.

That is, comparing with through hole 51 away from the rotating locus of the part at jack shaft 30 centers in two joints is if be in inside then both do not contact.In form of implementation, as shown in Figure 3, because the rotating locus of the most external radius of joint is set the internal diameter less than through hole 51 for, so bent axle 3 can rotate without barrier.

The following describes thirdly.Here, suppose that the thickness of first joint 32 is identical with the thickness of second joint 31 (middle axial size), the thickness of each joint is half of jack shaft height, and the thickness of dividing plate 50 is bigger than first joint 32 and second joint 31 thickness separately.Like this, when assembling, the dividing plate 50 that passes crank pin 14 contacts with second joint 31.At this moment, because through hole 51 does not also pass second crank pin 14, so second crank pin 14 has limited it and laterally moved.Therefore, under above-mentioned assumed conditions, can not dispose through hole 51 in the position of jack shaft 30.

In this form of implementation,, the form that is arranged on two joints between the crank pin is made following regulation from the relation of the thickness of the thickness of dividing plate 50 and joint.In when assembling, the face (in this example be the face of second crank pin 14 sides of first joint 32) opposite of first joint 32 of first crank pin, 13 sides by dividing plate 50 through holes 51 and to pass the distance of the faces (reference line) that stand facing each other with dividing plate 50 of second crank pin 14 of through hole 51 bigger than the thickness of dividing plate 50 not with first crank pin 13.The scope of setting up in this condition, the thickness of second joint 31 of second crank pin, 14 sides by through hole 51 can freely be set.According to this structure, second crank pin 14 can make dividing plate 50 move to preposition by after the through hole 51.

According to this form of implementation, the section configuration of second joint 31 is such section configurations, in the through hole 51 overlapping scopes of second crank pin 14 and the dividing plate 50 that is in a fixed position, its part is arranged, and this part has the section non-overlapping portions with first crank pin 13.Therefore, during assembling, second crank pin 14 and second joint 31 can pass through hole 51, can rotate non-contactly at the volley.

In addition, in this form of implementation, since when the section configuration that occupies jack shaft 30 most second joints 31 expands assembling on axle direction not with the section lap of first crank pin 13 by through hole 51 not, therefore increase the cross-sectional area of jack shaft 30, reduced the bending deflection of jack shaft 30.

Fig. 4 is the schematic representation of another modified example.Fig. 5 is the BB sectional view that expression is contained in first joint, 310 section configurations of the jack shaft 300 under the state in the through hole 51 of Fig. 4 dividing plate 50.Among Fig. 5, first joint 310 that is arranged on the jack shaft 300 of bent axle 3 enlarges by this way with respect to the shape on the vertical section of running shaft: have the part in the section that is included in in 2 crank pins and the section approaching first crank pin 13 of motor 2 but is not included in second crank pin 14.Among Fig. 5, RP1 is that the central axis with first crank pin 13 (solid line) is the outer radius at center, and RH is the inside radius of the through hole 51 (dotted line) of dividing plate 50.RJ is the outer radius of first joint 310, and less than RH.

The same with first form of implementation, the cross-sectional area of first joint 310 to maximum degree, therefore can improve the rigidity of jack shaft 300 in the expanded range that can assemble dividing plate 50, can obtain bending shaft distortion small construction.

In addition, first joint 310 has with respect to rotating shaft eccentric and unbalanced weight.In the structure of the uneven weight of coming two crank pins of balance and piston to cause by the rotor

2a balancer weight

40,41 up and down that is arranged at motor 2, by eccentric weight being set, can dwindle the balancer weight 40 that is arranged on rotor 2a bottom with the approaching side of motor 2.Thus, reduced the material of balancer weight, dwindled necessary space, further,, therefore, reduced the frictional loss of bearing, also had the effect that reduces vibration owing to can reduce the bending shaft distortion that the centrifugal force of counterweight causes.

In addition, in the assembling of this occasion, first crank pin 13 becomes the crank pin that passes through hole 51.

Fig. 6 shows another modified example.Fig. 7 be presentation graphs 6 jack shaft 300 first joint 311 that is connected in first crank pin 13 section configuration and be connected in the DD sectional view of section configuration of second joint 312 of second crank pin 14.

Minimum range LP1 between first crank pin 13 and second joint 312 is greater than the thickness B S of dividing plate 50.First joint 311, second joint 312 with respect to the vertical section of running shaft expand to respectively be included in this first connect crank pin that portion 311, second joint 312 be connected separately with respect in the vertical section of running shaft but the crank pin that is not included in the opposing party with respect to the part in the vertical section portion of running shaft.

Further, if the section configuration of above-mentioned two joints is the circle of concentric same external diameter, then can make both section configuration of joint that contains this part for maximum and be easy to processing.

According to this form of implementation, compare with form of implementation shown in Figure 2, can make the thickness of second joint 312 that does not pass through through hole 51 become big.The section configuration structure of the joint 311,312 of jack shaft 300 is: be in the overlapping scope of through hole 51 of a crank pin and dividing plate 50, and have the section non-overlapping portions with another crank pin.Therefore, during assembling, for with the distance of crank pin a joint greater than dividing plate 50 thickness, another joint can pass through hole 51 with the crank pin that is connected with this another joint, and two joints are on-stream rotates non-contiguously with through hole 51.Because therefore the section configuration of joint, can provide the diastrophic structure that has increased this part section configuration, dwindled jack shaft 300 at the scope intramedullary expansion that can adorn assembling dividing plate 50.

Fig. 8 shows another form of implementation of double cylinder rotary compressor 1 of the present invention.Its main formation indicates the symbol same with Fig. 1.

Pressing chamber among Fig. 8 is hereinafter described.Compression mechanical part 5 is made of first pressing chamber 31 and second pressing chamber 41.Top coffer 20 that first pressing chamber 31 processes by the first cylinder 6a, with main bearing 4 (radial bearing) one of supporting bent axle 3 and the dividing plate 50 that separates first pressing chamber 31 and second pressing chamber 41 constitute.Bottom coffer 60 and dividing plate 50 that second pressing chamber 41 processes by the second cylinder 6b, with supplementary bearing 8 one of supporting bent axle 3 constitute.

In addition, in Fig. 8, though Ben Tu does not have write up, the part of top coffer 20 be on thrust direction with a part of contacting structure of bent axle.And bottom coffer 60 becomes the structure of supporting the load of thrust direction with the part 100 of bent axle.

Fig. 9 is the schematic representation of expression part of the bent axle 3 of extraction from the double cylinder rotary compressor 1 of another embodiment of the present invention.Figure 10 is the plan view of observing from the axial A side of Fig. 9.

The inside of bent axle is provided with hollow portion 33 shown in Figure 10 (a) and Figure 10 (b).What Figure 10 (a) was different with Figure 10 (b) is that

jack shaft

112a, 112b roughly make elliptical shape in Figure 10 (a), roughly make positive toroidal in Figure 10 (b).

Shown in Figure 10 (a), the area (section) of the jack shaft 112a of first crank pin, 13 sides on axial Vertical direction is the structure to the eccentric direction expansion of first crank pin 13.That is the center of gravity P of jack shaft 112a, _U1Rotating center O from bent axle 3 ₁Prolonging direction to first crank pin constitutes with staggering.

Further, the jack shaft 112b of second crank pin, 14 sides is the structures towards the eccentric direction expansion of second crank pin 14.That is to say the center of gravity P of jack shaft 112a _S1Rotating center O from bent axle 3 ₁Prolonging direction to second crank pin constitutes with staggering.Thus, be to have the structure of step between jack shaft 112a and the jack shaft 112b.

Among Figure 10 (b), the section configuration of

jack shaft

112a, 112b is done circular.Thus, from the center of gravity P of bent axle 3 _U1, P _S1Rotating center O ₁The amount of staggering littler than the amount of staggering of Figure 10 (a).In addition, by shape being made round shape, the abnormity of Figure 10 (a) relatively, it is easier to process.No matter be under any situation in Figure 10 (a) and Figure 10 (b), owing to can enlarge the diameter of jack shaft, so can dwindle the distortion of jack shaft.

Figure 11 is the schematic representation of the part of the bent axle extracted out from another form of implementation of expression.Different with Fig. 9 is, the axle direction length of

jack shaft

112a and 112b slightly equally forms among Fig. 9, and the stepped part in this form of implementation makes the structure that staggers to first crank pin, 13 sides.That is to say that the height h1 of jack shaft 112a forms in the mode less than the height h2 of jack shaft 112b.

In the double cylinder rotary compressor of this form of implementation, as shown in Figure 8, thrust-bearing is provided with at 2 places.Thrust-bearing is the upside of first crank pin 13 and the downside of second crank pin 14.The setting of the compressor of this form of implementation is a upside with motor part 2, that is, first crank pin 13 is arranged on upside.Therefore, thrust load is big a side of downside thrust-bearing.Thereby, causing the occasion that crank pin tilts in distortion because of jack shaft, the unbalanced contact of axial thrust bearing is that downside one side is big.Therefore, as shown in figure 11, uprise by the jack shaft 112b that makes downside, can dwindle the downside crank pin is the distortion of toppling over of second crank pin, has reduced the unbalanced contact of axial thrust bearing.

The assembling procedure of the compressor of this form of implementation then, is described with Figure 22.In Figure 22, though with the top coffer serve as the below assemble, also can be reversed.Can also allow the bent axle be horizontal to assemble towards ground.

Figure 22 (1): with bolt the first cylinder 6a and piston 10a are assembled in top coffer 20 and main bearing 4 on the parts of one from top coffer 20 downsides.

Figure 22 (2): insert bent axle 3, make the hole portion of piston 10a consistent with the hole portion of main bearing 4.Then, adjust bent axle 3.The adjustment of what is called bent axle 3 is meant, by the location of bent axle, on one side with the gap between the space instrumentation measurement piston 10a and the first cylinder 6a, locatees on one side, from top coffer 20 downside bolton.

Figure 22 (3): insert dividing plate 50.The step that dividing plate 50 is inserted into

jack shaft

112a and 112b is a jack shaft 112a position contacting.

Figure 22 (4): the place of dividing plate 50 transversion malpositions to jack shaft 112a insertion.

Figure 22 (5): adjust dividing plate 50.

Figure 22 (6): insert the second cylinder 6b, imbed the bolt adjustment with not shown in the figures.

Figure 22 (7) inserts the bottom coffer 60 of double as supplementary bearing and adjusts.

Jack shaft 112 and dividing plate 50 structural relations when considering assembling, in the operation of Figure 22 (4), in order to allow dividing plate 50 dislocation, necessary condition is to make the thickness of dividing plate 50 thinner than jack shaft 112b.If the thickness of dividing plate 50 is thicker than jack shaft 112b, will conflicts with first crank pin 13, and can not make dividing plate 50 transversion malpositions.

In the formation of the bent axle 3 of Figure 11, because jack shaft 112b's ten minutes is thick, so be easy to assembling.

Figure 12 is the bent axle 3 of another form of implementation.Figure 13 is the plan view of the bent axle 3 from Figure 12 that the B direction of top is seen.Be with Fig. 9 difference, in Fig. 9, the periphery of jack shaft have with near the consistent part of the crank pin periphery of this jack shaft side.Relative with it, in this form of implementation, the jack shaft 112a (shown in the dotted line) of first crank pin, 13 sides has the center X with first crank pin 13 ₁X ₂Concentric structure.Further, the jack shaft 112b (shown in the dotted line) of second crank pin, 14 sides has the center Y with second crank pin 14 ₁Y ₂Concentric structure.Each jack shaft has the periphery structure more in the inner part than separately crank pin.Thus, can enlarge the jack shaft diameter and dwindle the diastrophic while, because concentric with crank pin, so, be easier to processing.

Figure 14 makes the stepped part between the jack shaft 112a of Fig. 9～Figure 13 and the 112b smooth and removes the structure chamfer.Thus, the stress that can reduce the bight is concentrated.

Figure 15 is the further expression sectional view of the compressor part of a form of implementation again.The difference of the form of implementation of this form of implementation and Fig. 9 is, is provided with in the centre of two jack shafts with assigned altitute and makes periphery and the consistent part of each periphery towards the two bias direction expansion of jack shaft.In other words, be the elongate sides and the structure that shortens the side conversion of the crank pin eccentric direction of step part.The stepped part 113a of jack shaft 113 makes the high limit to second cylinder, and stepped part 113b height is to the limit of first cylinder.According to this structure, the space that jack shaft 113 can use first crank pin, second crank pin and dividing plate to form to greatest extent reduces the distortion that the jack shaft bending causes.

Figure 16 is the further expression sectional view of the compressor part of a form of implementation again.This form of implementation is in the form of implementation of Fig. 9, though jack shaft is provided with 112a, 112b, jack shaft not to be set in this form of implementation with the difference of the form of implementation of Fig. 9.That is, first crank pin 13 and second crank pin 14 extend to the internal direction of dividing plate 50, no longer include jack shaft.As this structure, to compare with the situation of Fig. 9 that jack shaft is set～form of implementation shown in Figure 15, its bent axle does not bend.The hole that is arranged on the dividing plate 50 must be greater than the greatest circle diameter of the rotating locus of first crank pin 13 and second crank pin 14, to prevent contact.In this occasion, the sealing area of the necessity on the surface of contact between dividing plate 50, first piston 10a and the second piston 10b is dwindled greatly because of bore dia becomes.

In order to ensure sealing area, can on the big direction of the external diameter change of first,

second piston

10a, 10b, increase wall thickness.At this moment, because the volume of pressing chamber dwindles,, could keep volume well so the internal diameter of first,

second cylinder

6a, 6b also will become greatly.That is to say that the shape of cylinder makes flat pattern.Adopt this structure, the diameter of the bent axle 3 between two pressing chambers that formed by

cylinder

6a, 6b can be greater than the diameter of the bent axle 3 on the rotor 2a that is inlaid in motor part 2.

In addition, the situation that does not have jack shaft has as shown in figure 16 naturally improved the rigidity of axle, is difficult to produce bending deflection, but the occasion of jack shaft is being arranged, and its length also is short more good more.Thus, the occasion of jack shaft is being arranged, the thinner structure of dividing plate 50 is better.In addition, be thinned at dividing plate 50 under the situation of the thickness limit on the deformation intensity, still do not have the situation of jack shaft best.

Figure 17 is the further expression schematic representation of a form of implementation compressor part again.In the compressor of Figure 16, second crank pin 14 has prolonged dividing plate 50 thickness and has partly constituted.Thus, improve the bent axle rigidity, be difficult to produce bending deflection.In addition, the prolongation of crank pin also can be to prolong first crank pin.This situation is the same with Figure 14, and the occasion of jack shaft is being arranged, and its length also is short more good more.Further, about the compressor of thrust-bearing mechanism is set on the bent axle 3, also has the effect of this form of implementation.In addition, also the method with above-mentioned Figure 16 explanation is the same for the sealing area between first and

second piston

10a, 10b and the dividing plate 50.

Figure 18 is the form of implementation of further dwindling the formation of deflection of crankshaft distortion in the expression form of implementation shown in Figure 16.Be first crank pin 13 along the direction of top coffer prolongs, second crank pin 14 prolongs along the direction of bottom coffer 60 structure.

More than the actual measurement of Shuo Ming compressor crank shaft bending deformation quantity is very difficult.Therefore, the present inventor is by having resolved the bending deflection of bent axle with the computer simulation of limited factors method (FEM).Effect has from gas load, blade pass and crosses the power that the centrifugal force of power, bent axle and the rotor of spring (not shown) pushing rotor is obtained on bent axle.As a result, on the middle axial region between first crank pin and second crank pin, produce bending deflection.

Figure 19 shows the ASHRAE/T condition when using refrigeration agent R410A, promptly gas inhalating pressure be 0.996MPa, to discharge gas pressure be the condition of the 3.374MPa computer simulation results 510 during as initial conditions.In addition, also show overlappingly as the input analytical model 610 that calculates initial value.Bent axle partly produces bending deflection at jack shaft.The evaluating method of bent axle analysis result is, with the displacement of the bent axle of position, main bearing upper end portion counterpart, how to change as separately ratio with the minimum value in relative setting gap and to calculate.

Figure 20 is the schematic representation of relation of the minimum value C in the displacement B of the expression state crankshaft main bearing upper end portion down that produced the deflection of crankshaft distortion and setting gap.The bent axle 710 after the bending deflection and the bent axle 3 of original state have been shown among Figure 20.

Figure 21 is the schematic representation of the Computer simulation results of conclusion.Transverse axis is that the spring rate and the jack shaft cross-sectional area (be the cross-sectional area perpendicular to running shaft of jack shaft, comprise the area that connects all hollow hole portions of bent axle) of crankshaft material is long-pending, with X (kg) expression.The longitudinal axis is the minimum value C resulting value of the displacement B on crankshaft main bearing top divided by the setting gap, for the bearing play ratio, represents with Y.

In the figure, the bearing play is that 1 axle when above contacts with main bearing than Y, and this value increases to a certain degree, thereby the contact reaction force has increased frictional loss.In the bearing play than Y less than 1 o'clock, the axle do not contact with main bearing.

The solid line that Figure 21 represents is with the outer plug wire of the approximate mean value in exponential function peek strong point, has also expressed this formula simultaneously.In addition, to be respectively the exponential function that is similar to be outer plug wire maximum and hour to the up and down represented dotted line of the outer plug wire of above-mentioned mean value.In the bearing play than Y less than 1 occasion, when with reference to minimum outer plug wire, as can be seen, spring rate and middle cross-sectional area amass X 4.066 * 10 shown in F arrow in Figure 21 ⁶It is proper when kg is above.In addition, when the situation of considering average design and with reference to outside average during plug wire, as can be seen, X is 5.163 * 10 shown in the E in Figure 21 ⁶It is relatively good when kg is above.Further, with reference to outside maximum during plug wire, as can be seen, X is 7.454 * 10 shown in the G in Figure 21 when considering factor of safety ⁶It is relatively good when kg is above.In addition, for the gap as minimum value, be deformed into maximum result data in calculate resolving, usually, preferably satisfy the condition that F represents among Figure 21.Satisfy the spring rate and the jack shaft cross-sectional area of this condition by setting, can dwindle the bending deflection of axle, the loss of reducing friction, further, can suppress the increase in gaps such as coffer, rotor, dividing plate, can reduce the leakage of pressurized gas.

Though the spring rate of crankshaft material is difficult to produce bending deflection when high, be suitable,, consider Master Cost and processibility, preferably adopt the FC based material of cast steel, (spring rate is equivalent to 11000kg/mm for example to be equivalent to FC200～FC400 ²～18000kg/mm ²) material.Further, even the material of this scope because the low material price of spring rate can hang down, is determined so can use with the relation of medium axle diameter.When using the higher material of spring rate, can the increase cost because of becoming special specification etc.

According to above the present invention, in having the rotary compressor of multi cylinder, be intended to consider to design the bent axle of minor diameter, therefore can reduce the bending deflection between the crank pin, owing to reduced bent axle and bearing, crank pin and piston the inside or the end plate of airtight each cylinder and the not comprehensive engagement of dividing plate end face and piston end surface, thereby, can reduce frictional loss, reduce the loss of mechanical efficiency.Further,, therefore reduced leakage, suppressed the reduction of volumetric efficiency because the gap of the remaining part of bent axle and bearing, piston and end plate or dividing plate end face also diminishes.Because this effect, can suppress the reduction of the performance that crankshaft deformation causes.

Claims

1. multi-cylinder rotary air compressor, in seal container, by bent axle motor part and compressor section are linked together, described bent axle has with respect to first crank pin of rotating shaft eccentric and second crank pin, and described compressor section comprises: main bearing and the supplementary bearing of supporting described bent axle; Be arranged between described main bearing and the supplementary bearing, by having internal diameter greater than described first or first, second cylinder of separating of the dividing plate of the through hole of the second crank pin external diameter; In first, second cylinder, make first, second piston of eccentric motion along with the rotation of described bent axle; And described bent axle, it is characterized in that, also comprise be arranged on first, second crank pin that is contained in the inside that is formed at two pressing chambers in described first cylinder and second cylinder respectively and be connected between first, second crank pin portion that constitutes these joints as on the jack shaft of crankshaft, that stretch out towards described first, second crank pin eccentric direction separately and be arranged on a plurality of joints that the joint mode identical with the radius that rises with the spinning axle center in each crank pin portion is integrally formed.

2. multi-cylinder rotary air compressor, in seal container, by bent axle motor part and compressor section are linked together, described bent axle has with respect to first crank pin of rotating shaft eccentric and second crank pin, and described compressor section comprises: main bearing and the supplementary bearing of supporting described bent axle; Be arranged between described main bearing and the supplementary bearing, by having internal diameter greater than described first or first, second cylinder of separating of the dividing plate of the through hole of the second crank pin external diameter; In first, second cylinder, make first, second piston of eccentric motion along with the rotation of described bent axle; And described bent axle, it is characterized in that, comprise also being arranged on the jack shaft that connects between described first crank pin and second crank pin, that stretch out towards first and second crank pin eccentric direction separately and being arranged on a plurality of joints that the joint mode identical with the radius that rises with the spinning axle center in each crank pin portion is integrally formed that the rotating locus of the most outer diameter of these joints is set the internal diameter less than described dividing plate through hole for.

3. multi-cylinder rotary air compressor, in seal container, by bent axle motor part and compressor section are linked together, described bent axle has with respect to first crank pin of rotating shaft eccentric and second crank pin, and described compressor section comprises: main bearing and the supplementary bearing of supporting described bent axle; Be arranged between described main bearing and the supplementary bearing, by having internal diameter greater than described first or first, second cylinder of separating of the dividing plate of the through hole of the second crank pin external diameter; In first, second cylinder, make first, second piston of eccentric motion along with the rotation of described bent axle; And described bent axle, it is characterized in that, comprise also being arranged on the jack shaft that connects between described first crank pin and second crank pin, that stretch out towards the eccentric direction of these crank pins and being arranged on a plurality of joints that the joint mode identical with the radius that rises with the spinning axle center in each crank pin portion is integrally formed that the thickness setting of described dividing plate becomes the distance between the reference line of the face opposite with this crank pin of the joint that forms than a crank pin side and opposing side another crank pin and described dividing plate more thinner.

4. multi-cylinder rotary air compressor, in seal container, by bent axle motor part and compressor section are linked together, described bent axle has with respect to first crank pin of rotating shaft eccentric and second crank pin, and described compressor section comprises: main bearing and the supplementary bearing of supporting described bent axle; Be arranged between described main bearing and the supplementary bearing, by having internal diameter greater than described first or first, second cylinder of separating of the dividing plate of the through hole of the second crank pin external diameter; In first, second cylinder, make first, second piston of eccentric motion along with the rotation of described bent axle; And described bent axle, it is characterized in that, on the jack shaft that is formed between described first crank pin portion and the described second crank pin portion, have first joint and second joint, described first joint has such part: the vertical cross-section with respect to running shaft that is contained in the part in the through hole of described dividing plate is included in the part with respect to the vertical cross-section of the running shaft of a crank pin among described first crank pin or described second crank pin, and is not included in the part with respect to the vertical cross-section of another crank pin; And described second joint has such part: it is included in the vertical cross-section with respect to the running shaft of a crank pin, and be not included in the part of vertical cross-section of running shaft of another crank pin, and the maximum value of distance with profile and axis of rotation is less than the joint of the inside radius of described dividing plate through hole.

5. multi-cylinder rotary air compressor, in seal container, by bent axle motor part and compressor section are linked together, described bent axle has with respect to first crank pin of rotating shaft eccentric and second crank pin, be provided with jack shaft between described first crank pin and second crank pin, described compressor section comprises main bearing and the supplementary bearing of supporting described bent axle; Be arranged on first, second cylinder that separates by dividing plate between described main bearing and the supplementary bearing; In first, second cylinder along with first, second rotor of the rotating eccentricity of described bent axle; And described bent axle, it is characterized in that,

Described jack shaft is being axially arranged with stepped part, and the radially section of being distinguished by described stepped part of described jack shaft is configured greater than described first crank pin and described second crank pin lap of section radially.

6. multi-cylinder rotary air compressor as claimed in claim 5 is characterized in that,

The radially section of described jack shaft is greater than described first crank pin and described second crank pin lap of section radially, and the center of gravity of the described jack shaft of described first crank pin side and the described second crank pin side is eccentric in the length direction of each crank pin respectively.

7. the multi-cylinder rotary air compressor of putting down in writing according to claim 6 is characterized in that, the described first crank pin side of described jack shaft and the stepped part between the described second crank pin side are near the first set crank pin side of described main bearing side.

8. multi-cylinder rotary air compressor as claimed in claim 5 is characterized in that,

The radially section of described jack shaft is greater than described first crank pin and described second crank pin lap of section radially, and described jack shaft and described first crank pin and/or second crank pin are processed with one heart.

9. multi-cylinder rotary air compressor as claimed in claim 5 is characterized in that,

The radially section of described jack shaft is greater than described first crank pin and described second crank pin lap of section radially, and described first crank pin and second crank pin link together.