Background technology
Usually, the variable-displacement oblique tray type compressor in the Vehicular refrigeration equipment comprises: forward and backward housing, in two housings, formed some airtight spaces, and these spaces for example are crankshaft room, suction chamber, discharge chamber etc.; One cylinder block, it is installed between the forward and backward housing, and its circumferencial direction is provided with a plurality of cylinder-bore; One driving shaft, it is installed in rotation on the central part place of cylinder block; An one lug plate and a swash plate, they are installed on the driving shaft respectively; A plurality of pistons, they connect by the circumference of piston shoes along swash plate; One valve cell, it is disposed between cylinder block and the back casing; One control valve, it is used for the motion of control piston; And a spring, it is resiliently mounted on the swash plate, is used for when the lug plate does not rotate swash plate is supported on minimum oblique angle state.
In such variable-displacement oblique tray type compressor, in the process that cold-producing medium is compressed, the effect of inertia mass is played in the deadweight of piston, can stop piston to produce and move back and forth, and compression efficiency is reduced.In order to address the above problem, made piston with light material in the last few years, and the part in the piston was made hollow, thus further weight reduction.
The common practice is, in order to make the piston of hollow, a molded independently of each other first piston member and one second piston component, wherein, the first piston member has a bridgeware, it has a piston shoes holder, be used for being provided with therein the piston shoes that piston and swash plate are coupled together, and second piston component has a hollow space.Afterwards,, first, second piston component is joined together provisionally, then, welding is carried out on the surface that is engaged on first, second piston component, and utilized the electron beam welding under the vacuum condition that they are glued together mutually through after the machined.
But there are several problems in conventional hollow piston manufacture method: must process processing accurately to being engaged the surface; First, second piston component is assembled into together with expensive man-hour; And the processing to first, second piston component also is complicated and difficult, thereby this will reduce productivity ratio, and makes percent defective become very high.In addition, another problem that conventional hollow piston manufacture method also exists is: owing in the step of carrying out electron beam welding, can form some trickle holes at internal piston, so can reduce the durability of piston.The problem that conventional hollow piston manufacture method also exists is: because cold-producing medium and lubricating oil can leak in the hollow space through trickle hole, so shortage can appear in cold-producing medium and lubricating oil.Especially, there is such problem in common hollow piston manufacture method: because when carrying out electron beam welding, the welding region on the piston must be maintained under the condition of condition of high vacuum degree, so maintenance cost and manufacturing cost all can increase.
In order to address the above problem, No. 0959227 the European patent open file has comprised a kind of friction welding method, in the method, after first piston member and second piston component are molded into, on the front surface of first, second piston component, make parallel butting surface respectively, then, in atmospheric environment, under the mutual opposed state of two butting surfaces, utilize the frictional heat that is produced by first, second piston component phase mutual friction and make a hollow piston part.
But, under the condition of above-mentioned conventional method, because butting surface is the plane, and have small difference between the flatness of two butting surfaces, so the distribution of welding temperature on butting surface and inhomogeneous.In addition, owing to have angular velocity difference between the each point on the butting surface of first, second piston component, so temperature and weld strength are increasing on the direction in outside piston week gradually.But after welding, along with machining process is got rid of the outer perisphere of piston, it is lower that the weld strength of remainder just becomes.
In addition, No. 5460317 U.S. Patent Publication the method for a kind of friction stir butt weldering, this method is different from above-mentioned friction welding method.In No. 5460317 United States Patent (USP), on a continuous or continuous substantially material surface, a probe is set, the hardness of this probe material is greater than the hardness of above-mentioned material.Make after above-mentioned material and probe be in contact with one another, probe can be inserted in this material, meanwhile, produces relative periodic motion between probe and material.The heat that utilizes periodic motion to produce makes probe material on every side form a plasticizing zone.Then, by making material solidification it is glued together.
The advantage of this friction stir butt weldering is: and its ratio of defects is very low-and wherein defective for example is the distortion that is caused by the heat distortion; And be not subjected to the restriction of material.But also there is a shortcoming in friction stir butt soldering method: after carrying out friction welding (FW), probe can form a hole in the friction portion between material.
As shown in Figure 8, in the process of making a piston 1, a shortcoming of this friction stir butt soldering method is: because the friction portion between the first piston member 3 that has bridgeware 2 and second piston component 4-be to have formed a hole 5 in the welding portion, in the coating process after friction welding (FW), can't form the uniform overlay of thickness, so can make the durability variation of welding portion.
That is to say, because in the reciprocating motion process of piston 1, second piston component 4 that is used for the piston 1 of variable-displacement oblique tray type compressor can be swiped with the inner surface of cylinder-bore, in order to improve the sealing of abrasion resistance and raising second piston component 4 excircles, form layer of even on the outer peripheral face of second piston component 4 that comprises welding portion films, like this, wear process has just become a post processing (post-process).Thereby, as mentioned above, if in the welding portion of two-piston member, formed a hole, then Tu Fu liquid will seepage flow in this hole.When carrying out plastic working with this understanding, will form the part of a rising in the position of hole 5, thereby make film become uneven.Thereby the carrying out of wear process will be unusual, thereby cause the reduction of durability.
Also there is another shortcoming in above-mentioned friction stir butt soldering method: when probe is inserted in the welding portion between two parts, because the effect of pressure, may cause two parts to occur bending and deformation, thereby be difficult to make the piston that requires to have accurate external diameter.
For preventing this flexural deformation, the flat 11-156560 of Japan Patent open file discloses a kind of friction stir soldering equipment that can prevent that piston component from occuring bending and deformation, in this equipment, the relative both sides of probe-one or more support rollers promptly have been installed below the two-piston member, it contacts with the outer peripheral face of piston component.Support roller is supporting the pressure that is produced when probe inserts, thereby can prevent that piston component from bending.
But, because support roller is to install under such state: in this state, they are fixed to the bottom of supporting two members, so that two members are rotated on the support roller of fixing, two members must have accurate external diameter, two members accurately could be arranged on the axis of tumbler like this.
Thereby friction stir soldering equipment of the prior art can only be made the same a kind of piston with same outer diameter as.In order to make piston with various outer diameter, just must change welding equipment or make welding equipment independently according to external diameter, like this, manufacturing cost is improved.
Summary of the invention
Thereby, the present invention proposes in view of the above-mentioned problems, an object of the present invention is to provide a kind of friction stir welder, be used for making the piston of variable-displacement oblique tray type compressor, this method can be avoided forming hole in the welding portion between the two-piston member, the two-piston member utilizes friction stir weldering to connect together, thereby, can prevent that the durability of welding portion in coating process after the friction stir weldering and the wear process is lowered.
Another object of the present invention provides a kind of friction stir welder that is used for the piston of variable-displacement oblique tray type compressor, and this device can easily be welded to one another piston component together, no matter and the external diameter of piston component size why.
To achieve these goals, according to the invention provides a kind of friction stir welder, it comprises:
Be fixed on the rotation support device of worktable upper surface, it supports first, second piston component rotationally, first attaching parts that the first piston member has a bridgeware and stretches out from bridgeware, second piston component has one second attaching parts, these parts are connected with first attaching parts of first piston member, and having a hollow space, it forms by coupling together with the first piston member;
Welder is inserted in the welding portion of the first piston member that is supported on rotation support device and second piston component rotationally, carries out the friction stir weldering along the rotation direction of first, second piston component;
When first, second piston component is supported on the rotation support device, flexibly be installed in the support roller of the downside of first, second piston component, the axis of first, second piston component is arranged on the axis of rotation support device, when supporting first, second piston component, support roller vertically moves in predetermined altitude (H) scope; And
After welding portion being carried out the friction stir weldering by welder, welder is moved to the gearshift in precalculated position from welding portion.
The guiding elements that is used to control accurate position, axis is removably mounted on the top of rotation support device, guiding elements accurately is controlled at the axis of second piston component on the axis of rotation support device, simultaneously, upper surface pressurization to second piston component, second piston component is connected with the first piston member provisionally, overlaps with the axis of rotation support device so that flexibly be installed in the axis of the first piston member on the support roller.
Gearshift has one and is used for the servo motor of movable workbench to the preset distance place that the axis of the piston makes progress.
Two support rollers rotationally, be mounted adjacent one another on two support components, support component is installed in the top of the fixed rack on the upper surface that is fixed on workbench movably.
Fixed rack comprises a vertical through hole, and the lift component that links to each other with the lower surface of the support component that passes vertical through hole, and lift component is supported by spring ground.
Lift component has and protrudes out than the vertical through hole bottom in the outside in narrow lane footpath more, and lift component protrude out the end predetermined angle of inclination that tilts.
Fixture is installed in the below of lift component, in the axis of piston component with after the axis of rotation support device overlaps, when first, second piston component is supported on the rotation support device, the fixed part of fixed support roller by the ascending motion that stops lift component.
Fixture comprises the wedge shape fixed component, it has the front end as the inclination of lift component end, form the through hole of level within it, movable rod member is flexibly supported by the spring in the horizontal through hole inboard, and the connecting elements of end of movable rod member that is connected to the outside of the horizontal through hole that protrudes out the wedge shape fixed component.
Cylinder is connected to the end of connecting elements, and moves forward and backward connecting elements, so that the wedge shape fixed component advances or returns from the end of lift component by connecting elements.
In the following description, introduced other advantage, purpose and feature of the present invention, and for having understood hereinafter content or put into practice those of ordinary skills of the present invention, other advantage, purpose and feature of the present invention will be conspicuous.The structure that utilization is specifically indicated in text description part, claim and accompanying drawing can realize and reach these purposes of the present invention and other advantage.
Be understood that only be exemplary and indicative to general introduction of the present invention and detailed description hereinafter above, it just is used for the invention that claims limit is further explained.
The specific embodiment
To be explained in detail preferred implementation of the present invention below, express several example of the present invention in the accompanying drawings.
Fig. 1 has represented the structure of a variable-displacement oblique tray type compressor simply, and piston according to the present invention is installed in this compressor.
As shown in Figure 1, the variable-displacement oblique tray type compressor comprises: procapsid 11 and back casing 12, in two housings, formed some airtight spaces, and these spaces for example are the 11a of crankshaft room, suction chamber 12a and discharge chamber 12b; One cylinder block 13, it is installed between forward and backward housing 11 and 12, and its circumferencial direction is provided with a plurality of cylinder-bore 13a; One driving shaft 14, it is installed in rotation on the central part place of cylinder block 13, and has a lug plate 15; One swash plate 16, the side of itself and lug plate 15 is articulated, and has an inclination angle that can change with refrigeration load; And a plurality of pistons 20, they are connected with piston shoes 17, and these pistons are provided with along the circumference of swash plate 16, and can move back and forth in separately the cylinder-bore on cylinder block 13 along with the rotation of swash plate 16.
Be used in the piston in this variable-displacement oblique tray type compressor and be shaped on a hollow space, be used to reduce the inertia that produces owing to moving back and forth.
Fig. 2 has represented the detailed structure of piston.Piston 20 comprises: first piston member 23, it has a bridgeware 21, and first piston member 23 has a piston shoes holder, is used for settling therein the piston shoes that piston and swash plate are coupled together, and having first attaching parts 22, it longitudinally extends from bridgeware 21; And second piston component 26, the one side has second attaching parts 24 of extending in the vertical, so that be connected with first attaching parts 22 on the first piston member 23, and have a hollow space 25, by being coupled together, first piston member 23 and second piston component 26 just this hollow space 25 can be closed.
In addition, can on second attaching parts 24 of first attaching parts 22 of first piston member 23 and second piston component 26, be shaped on the support section 22a and the 24a of step respectively.
Piston 20 utilizes hereinafter friction stir soldering method to make generally.First, second piston component the 23, the 26th is molded into independently of each other, then, through after the machined, they is joined to together temporarily.Afterwards, after making a welder and welding portion on first, second piston component 23,26 contacts, in making first, second piston component 23,26 rotating process, utilize the frictional heat that is produced and two welding portions are welded to each other.
Fig. 3 has represented a friction stir soldering equipment, and it is used for making according to piston of the present invention, that be used in the variable-displacement oblique tray type compressor.
As shown in Figure 3, the friction stir soldering equipment that is used to make piston comprises: a rotation support device 31, it is fixed on the upper surface of a workbench 36, is used for supporting rotationally first, second piston component 23 and 26, and the two-piston member is connecting on same axis Face to face temporarily; And a welder 40, it contacts with the welding portion that is rotated first, second piston component 23,26 that bracing or strutting arrangement 31 supporting, and is to utilize frictional heat that two welding portions are welded together.
Rotation support device 31 comprises: one first support component 31a, and it is used for supporting rotationally a side of first piston member 23; One second support component 31b, it is used for supporting rotationally a side of second piston component 26; And a driver part (not showing out among the figure), be used for driving one of first, second support unit 31a and 31b.Certainly, driver part can freely be controlled the rotating speed (RPM) of first, second support component 31a, 31b per minute.One of in addition, among first, second support component 31a, the 31b-for example the second support component 31b is provided with a hydraulic cylinder 32, and it is set on the end of support component, is used to make piston to move forward and backward in the axial direction.
Welder 40 comprises: a servodrive (not shown) is used for moving in vertical direction the welding portion that is temporarily joined to first, second piston component 23,26 together, and is rotated the bracing or strutting arrangement support; And the probe 41 of a pin rod type, it is set on the front end of welder 40, thus when this probe was rotated the required frictional heat of generation welding by a spindle motor (not shown), it was inserted in the welding portion.
Specifically, between the first support component 31a and the second support component 31b, support roller 33 has been installed.Support roller 33 contacts with the bottom of first, second piston component 23,26, be used for keeping securely the interim connection status of first, second piston component 23 and 26, first, second piston component is wherein then being supported by first, second support component 31a, 31b.As shown in Figure 3 and Figure 4, two support rollers 33 are close mutually, so that can stably support columnar piston 20, roller is installed in rotation on two supporting members 34, supporting member 34 is installed in the top of a fixed rack 35, and stand is fixed on the upper surface of workbench 36.
If when its external diameter for example was installed on the support roller 33 for first, second piston component 23 and 26 of the piston 20 of 30mm-promptly coupled together temporarily, the axis of the axis of piston 20 and rotation support device 31 just overlapped.With this understanding, when the second support component 31b of rotation support device 31 shifts to the first support component 31a under the effect of hydraulic cylinder 32, a projection (not shown) on first, second support component 31a, 31b two ends central part will accurately be inserted in the centre bore 27, this centre bore 27 is formed on the two ends of first, second piston component 23,26, thus, piston 20 just has been supported on first, second support component 31a, the 31b.As mentioned above, under first, second piston component 23,26 is supported on above-mentioned condition on the rotation support device 31, the support force that 41 applied pressures and support roller 33 produced of popping one's head in offsets, thereby can prevent that first, second piston component 23 and 26 from bending, wherein, the pressure of probe is 41 to be inserted in the welding portion of first, second piston element 23,26 and to apply by popping one's head in.
But if external diameter is installed on the support roller 33 greater than the piston 20 of above-mentioned numerical value, then just can not align with the axis of rotation support device 31 in the axis of piston 20, and therefore, piston 20 just can not be supported on the rotation support device 31.
For addressing the above problem, be provided with a kind of support roller 33 of flexibly elevating movement among the present invention.Along with the elasticity elevating movement of support roller 33,, the axis of piston 20 is accurately overlapped with the axis of rotation support device 31 no matter why the external diameter of piston 20 is worth.
That is to say, shown in Fig. 4 a and Fig. 4 b, be set at fixed rack 35 on supporting member 34 bottoms, that be used for supported roller 33 and have a vertical through hole 51.In this vertical through hole 51, inserted a lift component 53.Lift component 53 vertically stretches out from the bottom surface of supporting member 34, and is flexibly being supported by spring 52.Lift component 53 comprises: the second piston piece 53a that is connected with the bottom surface of supporting member 34; And a support bar 53b, it is connected on the bottom surface of the second piston piece 53a, and its external diameter is less than the external diameter of the second piston piece 53a, and has a beveled end.The passage in the bottom of support bar 53b projects into the external world, and this passage is narrower than vertical through hole 51.
In addition, the second piston piece 53a is provided with a groove 54, and it is formed on the outer peripheral face of piston piece bottom, and spring 52 is installed on the outer peripheral face of support bar 53b.Under this condition, the front end of spring 52 is supported on the bottom of the second piston piece 53a, and the rear end of spring 52 is supported on the lock pawl 55, and lock pawl 55 is formed in the boundary of vertical through hole 51 and passage.
If the piston 20 that external diameter is bigger is installed on the support roller 33, then the load force of piston 20 will be applied on the support roller 33, and supporting member 34 utilizations are installed lift component 53 thereunder and flexibly moved.Thereby, can control the position of axis, make the axis of piston 20 and the axis of rotation support device 31 overlap.
Under this condition, represent as Fig. 5, in order to control the position of axis reliably, on the top of the second support component 31b of the top of one of two support component 31a and 31b-for example, a guiding elements 60 has been installed, its upper surface to piston 20 pressurizes, and it is being kept, piston 20 wherein flexibly moves on support roller 33.Guiding elements 60 comprises: a linkage section 60a, and it has connecting hole 60a1 and 60a2, and two connecting holes are used for linkage section 60a is detachably connected to the top of the second support component 31b; One extension 60b, it is extending longitudinally after linkage section 60a bending; One sloping portion 60c, the inclination angle that it becomes to be scheduled to extension 60b; And a retaining part 60d, it vertically bends from sloping portion 60c, and has an arc tips, is used to keep the outer surface of second piston component, 26 front ends.
As mentioned above, utilizing guiding elements 60 to make after the axis of the axis of piston 20 and rotation support device 31 accurately aligns, just can utilize rotation support device 31 support piston 20.After piston 20 is supported on the rotation support device 31, just must lift component 53 is fixing, be moved again to prevent supporting member 34.For this purpose, in lift component 53 support bar 53b below a fixture 70 is installed, to stop moving of lift component 53.
Fixture 70 comprises: the fixed component 74 of a wedge shape, wherein have a horizontal through hole 71, and similar with the end of support bar 53b, this member 74 also has an inclined-plane; One movable rod member 73, it is installed in the inside of horizontal through hole 71, and is flexibly being supported by a spring 72; And a connecting elements 76, it links to each other with an end of movable rod member 73 by a fastening means 75, and outside this end of movable rod member 73 projects into from the horizontal through hole 71 of wedge shape fixed component 74, and fastening means 75 for example is a bolt.In addition, on an end of connecting elements 76, connected a pneumatic cylinder 77, thereby, wedge shape fixed component 74 has been moved by moving forward and backward connecting elements 76.The number designation 78 that does not lay down a definition refers to the fastening means of bolt etc.
In fixture 70, when pneumatic cylinder 77 actions, under gas pressure, move connecting elements 76 front and back on the direction shown in the arrow, and meanwhile, the wedge shape fixed component 74 that links with connecting elements 76 also moves forward and backward.At this moment, be installed in movable rod member 73 in the horizontal through hole 71 of wedge shape fixed component 74 and be subjected to the elastic force effect of spring 72 and move, subsequently, the fixed component 74 of wedge shape also little by little moves.
Fig. 4 a has represented the state when wedge shape fixed component 74 turns back to the support bar 53b end of lift component 53.In this case since between the front end of the end of support bar 53b and wedge shape fixed component 74 gap of existence, so utilize lift component 53 that support roller 33 is flexibly raise or reduce a certain amount of " H ".
With this understanding, shown in Fig. 4 b, when wedge shape fixed part 74 travelled forward, the front end of its inclination contacted with the splay end of support bar 53b, and thus, lift component 53 will no longer can produce mobile.
Meanwhile, as shown in Figure 3, the workbench 36 that is installed on rotation support device 31 bottoms is connected with a gearshift 38, thus can by a servo motor 37 in a predetermined stroke range along the axis of the piston to translation.Thus, if under probe 41 conditions that have been inserted in piston 20 welding portions that supported on the rotation support device 31, make servo motor 37 work, then workbench 36 just can move in predetermined distance.The servo motor 37 of gearshift can be installed on the side of welder 40 or workbench 36.
Below, with reference to Fig. 6 the method for making piston 20 is described.
At first, make first piston member 23, it has bridgeware 21 and from bridgeware 21 extended first attaching parts 22.Then, make second piston component 26, it has second attaching parts 24 that are connected with first attaching parts 22, and has hollow space, and it forms by first piston parts 23 are connected together with second piston element 26.
As mentioned above, can utilize aforesaid technical process and form first, second piston component 23 and 26.In addition, also can comprise a step that forms step part, so that keeping connected state, thus first attaching parts 22 accurately are connected with columnar second attaching parts 24.
If finished the manufacture process of first, second piston component, then shown in Fig. 6 a, first, second attaching parts 22,24 are temporarily connected together.
Afterwards, first, second piston component 23,26 that is temporarily connecting is installed on the support roller 33, support roller is between first, second support component 31a and 31b of rotation support device 31, like this, first, second piston component 23 and 26 just has been supported on first, second support component 31a and the 31b.When second piston component 26 on being contained in support roller 33 moved under second effect of support component 31b at pneumatic cylinder, the projection that is located on the second support component 31b end central part will be inserted in the centre bore 27 of second piston component, 26 centre formation.With this understanding, the second support component 31b moves continuously to the first support component 31a, and the centre bore 27 of the first piston member 23 that temporarily is being connected with second piston component 26 contacts with the projection on the first support component 31a end, thereby first, second piston component 23 and 26 supports on first, second support component 31a and the 31b fastenedly.
At this moment, be about 30mm if be installed in first, second piston component 23 on the support roller 33 moving up and down and 26 external diameter, then first, second piston component 23 and 26 axis will coincide with the axis of support component 31a, 31b, thereby first, second piston component 23 and 26 can be subjected to being installed in the influence of the guiding elements 60 on the second support component 31b top hardly.But, if the external diameter of first, second piston component 23 and 26 greater than above-mentioned numerical value, then two axis just can not overlap, thereby must control the position of axis.In the Position Control step, top at second piston component 26 that is being connected with first piston member 23 temporarily is subjected under the condition of guiding elements 60 pressure, when support roller 33 moved down, the axis of second piston component 26 just coincided with the axis of the second support component 31b.At this moment, can change a new guiding elements 60 according to the external diameter of piston 20, so that keep the top of second piston component 26.
After the Position Control step of axis is finished, under the effect of pneumatic cylinder 77, the wedge shape fixed component 74 that is installed in the fixture 70 of support roller 33 belows will produce feed motion, thereby lift component 53 is fixing, and it is further mobile to prevent that thus supporting member 34 from producing.
Afterwards, shown in Fig. 6 b, welder 40 advances downwards, simultaneously driven and rotate by spindle motor, then, shown in Fig. 6 c, the probe 41 of welder 40 is inserted in first, second attaching parts 22,24, and these two parts are welding portions of first, second piston component 23 and 26.With this understanding, when the track of probe 41 on first, second attaching parts 22,24 of first, second piston component 23,26 moves, by rotating one time first support component 31a, the frictional heat that the probe of welder 40 just can utilize CONTACT WITH FRICTION to produce is welded together with first, second attaching parts 22,24.
When utilizing once the rotating after the welding finish first, second attaching parts 22,24 of rotation support device 31, the welder 40 in the welding portion separates with welding portion on first, second attaching parts 22,24 with being inserted into.At this moment, when welder 40 separates with welding portion, as shown in Figure 8, with welder 40 contacted parts (this part is comprised in the coating region) in formed hole 5, thereby, the welding after coating process in, coating fluid just with seepage flow in hole 5.With this understanding, when carrying out plastic working and milled processed, the thickness of coated film will not be uniformly, thereby can reduce durability significantly.
Thereby, for solving the above problems, shown in Fig. 6 d, make before welder 40 and welding portion be separated from each other, start servo motor 37, make the workbench 36 that is installed in rotation support device 31 belows piston axially on move, thereby the position of hole 28 can be moved to uncoated district from welding portion, to prevent in welding portion, forming hole.
By above-mentioned mobile step, shown in Fig. 6 e, when bridgeware 21 parts (this part is uncoated district) that are moved to first piston member 23 when the position of hole 28 go up, utilize spindle motor that welder 40 is turned back to its home position from first, second attaching parts 22 and 24 of first, second piston component 23 and 26.
Fig. 7 has represented the structure with the prepared piston 20 of said method.After carrying out friction welding (FW), be moved on bridgeware 21 parts of first piston member 23 by the probe 41 formed holes 28 of welder 40.
The number designation 29 that does not make an explanation refers to the trace of the probe 41 of welder 40, and this trace is formed on the welding portion of first, second attaching parts 22,24 of first, second piston component 23,26.
As mentioned above, after welder is inserted in the welding portion of the two-piston member that is being supported by rotation support device, just begin to carry out the friction stir weldering, rotation support device is moved to predetermined distance, thereby hole is formed in the uncoated district, like this, in the coating process after welding, can on the coating region of piston, form uniform coated film, thereby, the durability of piston can be improved.
In addition, according to the present invention, support roller can flexibly upper and lowerly move, to keep the interim connection status between the two-piston member, thereby, no matter why the external diameter of piston is worth, the axis of two-piston member all is easy to coincide with the axis of rotation support device, thereby can freely make piston according to size.
Although invention has been described above with reference to certain embodiments, the present invention also can't help these embodiment and limits, but limit by subsidiary claims.Can understand: those skilled in the art can make the foregoing description and changing and modification under the prerequisite that does not exceed the scope of the invention.