The present invention relates to a scroll compressor, and more particularly to a scroll compressor having volute teeth on both surfaces of a base plate of an orbiting scroll.
In a conventional scroll compressor, for example in a case of a vertical type scroll compressor, an orbiting scroll has volute teeth formed on both surfaces of an orbiting scroll base plate, and compression chambers are formed on an upper and a lower surfaces of the orbiting scroll by opposing a pair of fixed scrolls to the respective volute teeth. The orbiting scroll is driven by a shaft penetrating through each of the scrolls. In this case, a penetrating shaft has an eccentric shaft portion, and the eccentric shaft portion is supported by bearing at a penetrating hole of the orbiting scroll base plate for driving and rotating the orbiting scroll. Bearing formed at each penetrating hole of the two fixed scrolls supports the coaxial portions of the shaft at both sides of the orbiting scroll. (see for example, Japanese Patent Laid-Open No. 08-70592)
Patent Document 1: Japanese Patent Laid-Open No. 08-170592
The conventional scroll compressors are constructed as described above. In particular, in Patent Document 1, the eccentric distance of the eccentric shaft portion must be adjusted to form small compression chambers between side surfaces of volute teeth of the orbiting scroll and opposite side surfaces of the fixed scrolls. In this case, operating fluid may might leaked from between the opposing side surfaces of the volute teeth an hence deteriorated the function. Hence, cost tends to become high to precisely machine the eccentric distance of the eccentric shaft portion and to precisely assemble the portions.
Further, leakage of the operating fluid may seriously damage the performance in case the refrigerant has small molecular weight such as CO2 refrigerant or in case the refrigerant needs large pressure difference than conventional fluorine refrigerant.
The present invention is made to overcome the above described problems, and has an object to provide a scroll compressor that has favorable assembling property, that improves leakage of the operating fluid between volute teeth, and that has improved sealing and bearing structure.
A scroll compressor according to the present invention comprises a compression section provided in a closed container, the compression section including an orbiting scroll and a pair of fixed scrolls. The orbiting scroll has volute teeth formed substantially symmetrically on both surfaces of an orbiting base plate, and a main shaft is penetrated through and fixed at a center portion of the orbiting scroll. The pair of fixed scrolls is opposed to the both surfaces of the orbiting scroll and supports the main shaft by bearing action. Each of the fixed scrolls has volute teeth corresponding to each of the volute teeth of the orbiting scroll to respectively form compression chambers. A motor is provided in the closed container for driving the main shaft, and the main shaft has a notch part at a portion penetrating through the orbiting scroll and fixed scrolls. Further, a slider is provided that has an eccentric hole including a flat slide surface corresponding to the notch part, and is fitted to the main shaft where the notch part is formed. The slider is made slidable in a direction orthogonal to a length direction of the main shaft by the flat slide surface.
Further, a pair of balancers is fitted to the main shaft at both sides of the compression section for canceling imbalance associated with eccentric orbiting movement of the orbiting scroll,
The scroll compressor according to this invention is constructed as described above. Accordingly in case of assembling a vertical type, for example, the compression section is placed in a lower space of the container, the motor is placed in an upper space, and a glass terminal can be provided at an upper end portion above the motor. Therefore, after the compression section and the motor are all fixed inside the container, a lead wire can be finally connected to the terminal, and therefore, assembling property is improved.
Further, the substantially symmetrical volute teeth are formed on both surfaces of the orbiting scroll and the thrust loads caused by compression of an operating gas are cancelled by each other so that a thrust bearing does not have to be provided.
Accordingly, it can be prevented that an increase in abrasion loss and burning due to a broken oil film occurs due to its low circumferential speed and difficulty in forming oil film, that is caused in case of thrust bearing using a gas such as CO2 gas at high pressure with a high load.
Further, since the compression section is supported by bearing structure on both sides thereof, a moment does not occur to the shaft, and therefore, one-side abutment on the bearing due to tilt of the shaft may be prevented, and an associated increase in bearing loss and burning may be prevented.
Further, as described above, the volute teeth on both surfaces of the orbiting scroll are formed to be substantially symmetrical and have substantially the same heights, and therefore, they are simple in structure and can be formed easily.
1 closed container, 2 motor, 3 compression section, 4 lubricating oil storage chamber, 5 suction pipe, 6 glass terminal, 7 main shaft, 8 discharge pipe, 9 first balancer, 31 orbiting scroll, 31A core part, 31B orbiting base plate, 31D orbiting bearing, 31E seal ring groove, 31F abutment joint, 31G seal ring, 31H tip seal groove, 31J Oldham groove, 31K communication port, 32 compression chamber, 33 upper fixed scroll, 33B main bearing, 34 lower fixed scroll, 34A fixed base plate, 34C main bearing, 34D recessed portion, 34E volute tooth, 34F discharge port, 34G discharge passage, 34H discharge valve, 34J suction port, 35 Oldham joint, 71 notch part, 72 slider, 72A flat slide surface, 72B eccentric hole, 76 oil feed pump, 77 lubricating oil, 78 second balancer, 91 fitting hole, 92 cylindrical body, 93 projected part, 94 flange portion.
First, the construction of a compressor, which is a basis of this invention, will be described based on the drawings.
In a scroll compressor of
A suction pipe 5 is provided for sucking a suction gas in the closed container 1 at an intermediate portion between the motor 2 and the compression section 3, and a glass terminal 6 is provided at an upper end of the closed container 1 at the upper side of the motor 2.
The motor 2 is constructed by a known stator 21 formed into a ring shape, and a rotor 22 supported to be rotatable in the inside of the stator 21. A main shaft 7 is fixed to the rotor 22, and the main shaft 7 penetrates through the compression section 3 to extend to the lubricating oil storage chamber 4. The relationship between the compression section 3 and the main shaft will be described later.
The compression section 3 includes an orbiting scroll 31 having volute teeth formed on an upper surface and a lower surface of an orbiting base plate in substantially symmetrical shape with substantially same heights, an upper fixed scroll 33 which is disposed to be opposed to the upper surface of the orbiting scroll 31 and has an involute tooth which corresponds to the upper surface volute tooth of the orbiting scroll 31 to form a compression chamber 32, a lower fixed scroll 34 which is disposed to be opposed to the lower surface of the orbiting scroll 31 and has a volute tooth which corresponds to the lower surface volute tooth of the orbiting scroll 31 to form the compression chamber 32, and a known Oldham joint 35 which is placed between the lower fixed scroll 34 and the orbiting scroll 31.
The detailed construction of the orbiting scroll 31 will be described with reference to
As shown in the enlarged view of
In the core part 31A, a volute tooth is usually formed in an involute curve or an arc outward from its center, and the number of turns of the volute tooth is proportional to the compression ratio of the compressor. In the case of using an HFC gas in air-conditioning for example, the compressor is operated at the compression ratio of 3, so that the number of turns of the volute tooth needs to be three or more. But in the case of using a CO2 gas with a low compression ratio, the compressor is operated at the compression ratio of 2, so that the number of turns of volute tooth becomes two or more, and thus it is possible to reduce the number of turns of the volute tooth by one turn as compared with the case of the HFC gas.
Accordingly, by decreasing the turns of the volute tooth by the amount of one turn or more at the center portion, it becomes possible to form the hole 31C in the center portion of the core part 31A for penetrating the main shaft and to provide the orbiting bearing 31D.
This can be applied for any other case where the low compression ratio is a rated condition as well as the case of CO2 gas.
Two or more turns of a volute tooth are formed respectively on the upper surface and the lower surface of the orbiting base plate 31B in involute curves or arcs substantially symmetrically and substantially in the same height as the core part.
“Substantially symmetrical” means that the thickness t, height h, pitch p and the numbers of turns n of the volute tooth shown in
Therefore, the thrust forces, which act on the orbiting scroll 31 to upward and downward direction at the time of compression, are cancelled out, and the load in the thrust direction becomes substantially zero, so that the thrust bearing can be eliminated.
Since the thrust forces can be cancelled out by each other, the tooth height of the scroll can be made low, and the volute may be enlarged in the diameter direction into a so-called thin pancake shape, whereby the radial direction force can be made relatively small, and reliability of the journal bearing can be enhanced.
The volute teeth on the upper surface and the lower surface are made substantially symmetrical, but in actual a slight difference is made to occur in the gas pressures of the upper and lower compression chambers for example in order to give rise a slight thrust force downwardly.
As a result, the volute tooth at the lower side of the orbiting scroll 31 is brought into pressure contact with the lower fixed scroll 34, and the volute tooth at the upper side has a gap from the upper fixed scroll 33. Therefore, in the volute tooth of the upper side, a tip seal groove 31H is formed at the upper end surface of the volute tooth as shown in
The seal ring 31G provided at the core part 31A is formed as a ring which is rectangular in section as shown in
The separating action is performed by contact sealing of the seal ring 31G by pressure difference. The seal ring 31G is pressed against the right side wall and to the upper side fixed scroll 33 in the seal ring groove 31E being pressed from the high pressure left side and the lower side as shown by the arrow in
In this case, sliding contact occurs at the surface of the fixed scroll, but the sliding is at a low circumferential speed of a grinding motion in a small radius as the tip seal, and therefore, friction and sliding loss are small.
In the core part 31A, a communication port 31K is formed at the outer side of the seal ring groove 31E. The communication port 31K penetrates through the orbiting base plate 31B in the vertical direction and combines the gases, which are compressed in the compression chambers on both surfaces of the orbiting scroll 31 as will be described later, to flow to a discharge port of the fixed scroll.
The communication port 31K is formed as a long hole along the seal ring groove 31E, or is formed as a plurality of holes disposed adjacently each other to perform substantially equivalent action as the long hole, and is provided at the position which is not across the compression chambers, and always communicates with the discharge port of the fixed scroll, that will be described later.
Next, the detailed construction of the fixed scroll will be described with reference to
As shown in
A recessed portion 34D is formed in the peripheral portion of the main shaft bearing 34C, i.e. the center portion of the fixed base plate 34A, and accommodates the core part 31A of the orbiting scroll 31 and allows the orbiting movement of the orbiting scroll 31. At the outer periphery of the recessed portion 34D, a volute tooth 34E is formed in two or more turns in the same size as the volute tooth of the orbiting scroll 31 in the volute curve or the arc but is rotated 180 degrees in phase.
A discharge port 34F is provided in the recessed portion 34D for discharging the compressed gas without crossing the seal ring 31G of the orbiting scroll.
The discharge port 34F is formed as a long hole along an inner side of the innermost volute tooth of the fixed scroll, or is formed as a plurality of holes disposed adjacently each other to perform substantially the equivalent action with the long hole, and is provided at the position which always communicates with the communication port 31K of the orbiting scroll.
Further, a discharge passage 34G is formed which communicates with the discharge port 34F and flows the compressed gas out of the compressor via a discharge pipe 8 (
In an outermost peripheral portion of the lower fixed scroll 34, a suction port 34J is provided as a suction inlet of the suction gas to the lower compression chamber. A discharge port 34K (
The check valve 34L is provided to prevent that oil foams with remaining refrigerant and flows out of the compressor when actuating the compressor. The suction path for suctioning gas into the compression chamber is formed as shown by the broken line arrow G in
As shown in
On the upper and the lower surfaces of the slider 72, recesses 73 are formed for the paths of lubricating oil. On the surface of the outer peripheral portion of the slider 72, which is in contact with the orbiting bearing 31D, an oil feed groove 74 is formed in the vertical direction and allows the recess 73 on the upper surface to communicate with the recess 73 on the lower surface.
In main shaft 7, an eccentric oil feed hole 75 is formed and extended from the lower end to reach the main shaft bearing 33B of the upper fixed scroll 33. An oil feed pump 76 is provided at. the lower end of the main shaft 7 and is immersed in lubricating oil 77 at the lower end of the closed container 1.
Next, an operation of the first embodiment will be explained.
The gas, which is sucked into the closed container 1 from the suction pipe 5, flows into a part of the motor 2. After cooling the motor 2, the gas is taken into the compression chambers 32 on the upper and lower surfaces of the orbiting scroll 31 from the suction port 33A provided in the outer peripheral portion of the upper fixed scroll 33 as shown by the broken line arrow G.
Thereafter, the orbiting scroll 31 performs orbiting movement, without rotating around its own axis, with respect to the upper and the lower fixed scroll s 33 and 34. A pair of crescent compression chambers, which are formed by the known compression principle, reduce their volumes gradually toward the center. The pair of compression chambers finally communicate with each other in the innermost chambers in which the discharge port 34F is present, and flows are guided outside the compressor through the discharge passage 34G.
In the state of
A pair of compression chamber A and B moves toward the center while reducing in volume.
c) shows the state of the orbit angle of 180°, and
In
The discharge port 34F is provided in the innermost chamber which does not contribute to compression, and is positioned not to cross the aforementioned seal ring 31G during the compression step, so that a sufficient flow passage is ensured. For that purpose, the curve of the core part and the curve of the inner surface of the volute tooth of the fixed scroll are formed to secure a clearance space in order not to block the discharge port 34F completely with the core part 31A during the compression step.
In a type of compressor in which an integrated volume ratio is fixed as a scroll compressor, compression insufficiency loss occurs in the final discharge step when the operation is performed with a higher compression ratio than a set compression ratio. The compression insufficiency loss means that the pressure in the innermost chamber is higher than the pressure of the compression chambers A and B, when the innermost chamber and the compression chambers A and B communicate each other as in
Therefore, the top clearance volume is restrained to a minimum, which is defined as the volume upstream of the discharge valve 34H, namely the total sum of the innermost chamber, the discharge port 34F and the communication port 31K. Further, a little relief portion 34M is formed in the core part 31A. The relief portion 34M is to secure a flow passage by expanding width with reduced radius of the curvature.
Next, oil feed will be described. As shown in
Thereafter, the lubricating oil passes the flat portion of the notch part 71 formed on the main shaft to flow down and, via the recess 73 formed on the upper surface of the slider 72, flows into the oil feed groove 74 which is formed in the vertical direction on the outer peripheral surface of the slider 72 to lubricate the slider 72.
The oil, which flowed down in the oil feed groove 74, passes via the recess 73 on the lower surface of the slider, and passes through a return hole 34N formed in the lower fixed scroll 34, and flows towards the center direction of the main shaft, and flows down in the notch part 71 of the main shaft 7 again while feeding oil to the main shaft bearing 34C of the lower fixed scroll 34, and is discharged outside the main shaft from the lower end portion of the main shaft bearing 34C as shown by the arrow, and returns to the lubricating oil storage chamber 4.
As described above, the oil feed path forms a circulating closed loop from feeding through discharging without directly contacting the flow of the suction gas.
Accordingly, it is prevented that the oil is caught by the suction gas and flows out of the compressor.
The compressor is constructed as above, and therefore the compressor is suitable, for example, in a case where a heat exchanger volume of an air conditioner is made large for energy saving, in a case where the apparatus is tuned to perform a normal operation with a low compression ratio as an ice thermal storage system for peak-cut and load-leveling, and in a case where a refrigerant such as a CO2 gas is used and normal operation is performed at a low compression ratio for air conditioning operation. A high efficiency of the apparatus can be maintained.
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
With regard to the main shaft 7 shown in
The notch part 71 forms a flat surface on the lower portion of the main shaft 7, and this notch part 71 is formed from the portion in contact with the main shaft bearing 33B of the upper fixed scroll 33 down to the lower end of the main shaft as described in
As shown in
As for the outside diameter of the main shaft 7 and the inside diameter of the eccentric hole 72B of the slider 72, the outside diameter of the main shaft is set to be a little smaller, as a result of which, the notch part 71 and the slide surface 72A can slide a little parallel with each other.
The operation principle of the slider 72 will be described with reference to
When the main shaft 7 rotates, the orbiting scroll 31 generates a centrifugal force, and the force acts in the direction shown by Fc in
As a result, as shown in
Since the contact sealing between the volute teeth is made by the slider 72 like this, leakage between the volute teeth is restrained to the minimum and a scroll compressor with high compression efficiency can be obtained.
Especially when a gas, which has a large pressure difference and easy to leak such as a CO2 gas, is used, the slider 72 is indispensable.
Next, a second embodiment of this invention will be described with reference to the drawings.
A first balancer 9 is constructed by providing a projected part 93 which acts as a balancer at one side of a cylindrical body 92 having a fitting hole 91 to the main shaft 7. A flange portion 94, which forms a thrust surface, is formed at one end of the cylindrical body 92.
The first balancer 9 is fitted onto the main shaft 7 between the rotor 22 of the motor 2 and the upper fixed scroll 33 with the flange portion 94 at the lower side so that the first balancer 9 acts as an upper balancer of the compressor.
The first balancer 9 functions as a balancer for the compressor and further functions to position the rotor 22 of the motor 2 in the axial direction by setting the length of the cylindrical body 92. The flange portion 94 at the lower end portion forms a thrust surface and abuts on the upper surface of the fixed base plate of the upper fixed scroll 33 so that it receives the entire weight of the main shaft 7 and the rotor 22 here to be rotated.
Specifically, the thickness of the sidewall of the oil feed pump 76 is formed to be partially thick by decentralizing the pump inside and outside diameter along the rotary shaft.
By constructing like this, imbalance rotation is made, and the second balancer is given the function of both the oil feed pump and the lower balancer of the compressor.
The eccentric amount can be made small by forming the balancer over the substantially entire length of the oil feed pump 76. Therefore, even when the eccentric portion is immersed in the oil and rotates, agitation loss of the oil by the eccentric portion can be restrained to the minimum.
Balancing is set so that Fc=Fc1−Fc2, Fc1×L1=Fc2×L2 as is known.
However, when the orbiting scroll 31 and the fixed scrolls 33 and 34 contact each other at the volute teeth, the centrifugal force of the orbiting scroll 31 is all received by the volute teeth of the fixed scrolls 33 and 34. Therefore, the moment Ml occurs to the main shaft 7 by the Fc1 and Fc2 as in
As a result, the main shaft tilts and rotates as shown in the drawing, and the main bearings 33B and 34C are easily damaged and worn by so-called one-side abutment.
Thus, as shown in
This invention can be favorably utilized in an air conditioner or an ice heat storage system that are tuned to be normally operated with a low compression ratio, or in an air conditioner using a refrigerant such as a CO2 gas and having a low compression ratio at normal operation.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2004/019238 | 12/22/2004 | WO | 00 | 6/20/2007 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2006/067844 | 6/29/2006 | WO | A |
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Number | Date | Country | |
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