JPH03217678A - Hermetic scroll compressor - Google Patents

Abstract

PURPOSE:To improve the reliability of respective bearings by maintaining favourable bearing conditions with no eccentricity by means of the auto-centering action of the bearings even when some off-center is generated between central axes of a crankshaft and a sealing envelope from assembling errors in the assembling work of a compressor. CONSTITUTION:A lower bearing 7c of a motor 10 provided in the opposite side of a scroll section is enabled to change its situation freely in a bearing housing by forming the peripheral portion of the bearing spherical. Therefore even when a slight off-center is generated between the central axes of a sealing container 16 and a crankshaft 6a in the assembling work, or a slight deformation of the crankshaft 6a is generated during operation by the effect of centrifugal forces of a rotating scroll 2 and a balance weight 4 or the like on the crank-shaft 6a, by means of the auto-centering action of the bearing, the cylinder portion of the crankshaft 6a and the inner cylinder portion of the bearing 7c can be always kept in parallel to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positive displacement compressor applied to refrigeration and air conditioning, and in particular a scroll compressor that houses a compression mechanism and an electric element in a closed container. Regarding compressors.

[Conventional technology]

Regarding the arrangement and structure of bearings in conventional scroll compressors, for example, as described in Japanese Patent Laid-Open No. 59-28088, a crankshaft connected to a motor rotor has bearings arranged on both sides of the motor. and is supported. The bearings disposed on both sides of the motor constitute a fixed bearing. Furthermore, the bearings are housed in a bottom case at the bottom of the motor, and each bearing is forcibly supplied with oil from the outside via the bottom case.

[Problem to be solved by the invention]

The above conventional technology stores the bearing provided at the bottom of the motor in a bottomless bearing housing that is bolted to an airtight container.
Furthermore, since this bearing housing is positioned relative to the closed container by the so-called inlet part, care must be taken during assembly to align the center of the main shaft with the center of the bearing at the bottom of the motor. It needed to be done.

In addition, when the scroll compressor is operated, the main shaft is affected by the centrifugal force of the orbiting scroll and the centrifugal force of the balance weight, as well as the electromagnetic attraction force caused by the uneven clearance between the stator of the electric element and the rotor. acts, causing complex deformation of the principal axis. As seen in conventional technology, in many scroll compressors, the upper part of the main shaft (the part on the orbiting scroll side from the motor) has higher rigidity, so the amount of deformation is greater at the lower end of the motor, and all bearing parts are deformed. However, there is a problem in that uneven contact occurs due to deformation of the crankshaft, reducing the reliability of the bearing.

In addition, the bottom punch also serves as a lower bearing, and for accurate positioning with respect to the center of the shaft, the position of the bolt insertion hole on the outer flange and the part of the spigot must be machined with higher precision. However, since assembly must be performed with great care, productivity is low. Another problem is that lubricating oil for the bearings and sliding parts must be supplied from outside the container, which necessitates the addition of lubricating oil pumping equipment and piping, which increases the overall size and complexity. There was a problem.

An object of the present invention is to prevent the bearing at the lower part of the motor from tilting within the bearing housing in accordance with the deformation of the crankshaft, thereby preventing the bearing from hitting one side.

[Means to solve the problem]

In order to achieve the above objective, a so-called self-aligning type bearing, which has a cylindrical inner circumference and a spherical outer circumference, is arranged in the lower bearing housing to pivotally support the lower end of the crankshaft. This is what I did.

[Effect]

The bearing 7c provided on the side opposite to the scroll portion of the motor 10 has a spherical outer peripheral portion, so that its posture can be freely changed within the bearing housing. Therefore, if a slight deviation occurs between the center of the closed container 16 and the center of the crankshaft 6 during assembly, or if the centrifugal force of the orbiting scroll 2 and the centrifugal force of the balance weight 4 acts on the crankshaft 6 during operation, As a result, even if the crankshaft 6 is deformed, the self-aligning function allows the cylindrical portion of the shaft 6 and the inner circular portion of the bearing 7c to always maintain correct parallelism with each other. In particular, it is technically very difficult to completely balance the unbalance with respect to the rotation speed of the crankshaft 6, and it is generally unavoidable that some unbalance remains. However, due to this unbalance, the motor 10b is rotated at 5,000 rpm by an inverter (rotational speed variable device, not shown).
When the speed reaches a high speed of 1 minute or more, the crankshaft 6 receives a large force and tries to bend, but the self-aligning bearing 21
Due to this arrangement, the amount of deformation is kept small, and the attitude of the bearing itself can be suitably changed according to the slight deformation, so the crankshaft 6 can be supported without uneven contact at the bearing part. . Therefore, since the degree of uneven contact in the main bearing 7a can be alleviated, the reliability of the bearing can be maintained high even during high speed rotation.

In addition, the lower end of the crankshaft 6 is immersed in oil, and the difference in pressure between the upper and lower parts of the crankshaft 6 causes the refrigerating machine oil 26 to pass through the oil supply hole 31 provided in the crankshaft 6 to each sliding bearing. 7, and the supplied oil returns to the lower part of the sealed container and is again used for lubrication, thus forming a self-recirculation system.

Furthermore, the arrangement of the bearing 7c always maintains a suitable air gap between the stator loa of the motor 10 and the rotor 10b, which reduces electromagnetic torque loss and improves efficiency.

【Example〕

An embodiment of the present invention will be described below with reference to FIG. The casing 16 constitutes a closed container with a lid casing 17 and a bottom casing 18, and houses therein a motor 10, a compression mechanism including a fixed scroll 1 and an orbiting scroll 2, and lubricating oil 26. The motor 10 consists of a stator 10a and a rotor 10b.
b has a key 25 between it and the crankshaft 6, thereby transmitting the rotational torque of the motor 10 to the crankshaft 6. The crankshaft 6 includes a sliding bearing 7a provided in the frame 3 and a lower bearing (sliding bearing) 7 provided in the lower bearing housing 21.
It is supported by c. In addition, the crankshaft 6
It consists of a straight part 6a and a part (crank part) 6b eccentric to the straight part 6a, and an oil supply hole 31 penetrating from end to end is provided inside. Furthermore, a balance weight 4 is provided above the crankshaft 6 and a counterweight 11 is provided below the motor 10 in order to maintain the balance of the rotating body during operation. The crankshaft 6 and the motor rotor 10b are fixed with a lock nut 12. The frame 3 is fixed to the casing 16 by a plurality of special bolts 30 provided on the circumference. Furthermore, the frame 3 is arranged such that an Oldham ring 8 for preventing rotation of the orbiting scroll 2 is slidable thereon. Further, an orbiting scroll 2 is disposed thereon, and an Oldham ring 8 is provided in a sanderch shape between it and the frame 3. The Oldham ring 8 partially has a convex portion (not shown), and this convex portion engages with the frame 3 and the back side of the orbiting scroll 2, respectively. The engaging portion with the frame 3 and the engaging portion with the orbiting scroll are arranged so as to be perpendicular to each other.

The orbiting scroll 2 has a bearing portion 7b, and this portion engages with an eccentric portion of the crankshaft 6. The orbiting scroll 2 includes a wrap portion 2a formed in a spiral shape and an end plate portion 2b. The fixed scroll 1 also includes a wrap portion 1a and an end plate portion 1b which are formed in a spiral shape. The orbiting scroll 1 and the fixed scroll 2 are engaged with each other with their lap portions facing inside, and together form a compression working chamber 19. The compression chamber 19 and the back pressure chamber 20 communicate with each other through an intermediate pressure hole 20 provided in the end plate portion 2b of the orbiting scroll 2. Further, the outer circumferential portion of the end plate 2b is supported by the frame 3 and the outer circumferential portion of the fixed scroll 1 in a sandwich-like manner so that the orbiting scroll 2 can smoothly move while being engaged with the fixed scroll 1. The fixed scroll 1 has its outer peripheral portion fixed to the frame 3 with bolts 32. The fixed scroll 1 also has an inlet 23 extending to its outer circumference and a discharge port 13 at its center, and is provided with a check valve l4 and a retainer 15 opposite the discharge port 13.

Next, the operation will be explained according to FIG.

When electricity is supplied to the motor 10 from the outside via the hermetic terminal 22, the motor rotor 10b rotates, and the crankshaft 6 rotates accordingly. As a result, the orbiting scroll 2 rotates through the intervention of the Oldham ring 8, and the working fluid flows in from the suction port 23 and is taken into the compression working chamber 19, and as the orbiting scroll moves, the working fluid is compressed. The high-pressure working fluid is discharged from a discharge port 13 provided at the center of the fixed scroll 1. During this compression operation, the appropriately pressurized fluid fills the back pressure chamber 5 through the intermediate pressure hole 20.

As a result, the thrust force on the orbiting scroll 2 generated by the pressure in the back pressure chamber 5 exceeds the total thrust force generated by the gas force in the compression working chamber.
Since the orbiting scroll is pressed against the fixed scroll 1 during operation, a stable compression operation is performed. Further, the high-pressure gas discharged from the discharge port 13 flows into the motor chamber 9 from between the closed container 16 and the compression mechanism section including the scroll section 2, where the gas and lubricating oil are separated and the gas is It flows out of the compressor from the discharge pipe 24.

On the other hand, the separated lubricating oil flows downward due to gravity and reaches the oil reservoir 26. The lubricating oil is stored in this oil reservoir 2.
6 and are supplied to the bearings 7 through oil supply holes 31 provided in the crankshaft 6 due to the pressure difference. especially,
After lubricating the bearing parts 7a and 7b, it is discharged into the back pressure chamber 5, and then passes through the intermediate pressure hole 20 to the compression working chamber 1.
The oil enters into the oil reservoir 9 and is further discharged from the discharge port 13 together with the gas, and returns to the original oil sump 26. A valve plate 14 and a retainer 15 provided opposite to the spout 13 prevent high-pressure gas remaining in the closed container 16 from flowing back toward the suction pipe 23 when the compressor is stopped. , airtight container 1
When the maximum pressure in the compression working chamber is lower than the pressure in 6,
It works to prevent high pressure gas from flowing back into the compression chamber.

Next, still another embodiment will be described with reference to FIG. 2. In the case of this embodiment, the basic configuration is the same as that of the first embodiment. Therefore, the points that are different from FIG. 1 will be additionally explained. In this embodiment, an upper case 17 and a bottom case 18 are assembled and welded to a case 16 to form a closed container. Furthermore, the suction pipe 23 is press-fitted so as to penetrate the case 16 and reach the fixed scroll 1, and the case 16 and the suction pipe 23 are welded to maintain sealing performance. Further, the frame 3 that supports the compression elements and the like is fixed to the case 16. Further, the motor rotor 10b is also fixed to the shaft 6a by means such as press fitting. A spherical bearing 7c provided at the lower end of the shaft 6a is attached to a bearing holder 42.
a and 42b, and is fixed to the bearing support plate 21 with a plurality of fixing bolts 41. Further, this bearing support plate 21 is fixed to the case 16 by means such as welding. A plurality of support legs 40 are arranged along the circumferential direction of the case 16, thereby forming a vertical compressor. The operation and effect in this embodiment are as follows.
Since there is no major difference from the embodiment shown in the figure, the bearing 7c
This will be explained below. First, we will explain step by step how to assemble. Motor stator 10a in case 16
Fixed to. Next, prepare a structure in which the shaft 6 is assembled to the frame 3 and the motor rotor 10b is attached to the shaft 6, and this combination is inserted from the top of the case 16, and the outer circumference of the frame 3 is fixed to the case 16. . Now, frame 3, motor 10 and shaft 6
However, in this state, there is no compensation that the case 16 and the center of the shaft 6 match at the lower end of the shaft 6. Therefore, when assembling the lower bearing 7c, the spherical portion changes its posture appropriately, and the bearing 7c can be set in the correct state without hitting the shaft 6 unevenly. Then, in this state, the fixing bolt 41 of the lower bearing 7c is tightened to fix the spherical bearing 7c via the bearing holder. By fixing the fixing bolts 41, the spherical portions of the bearing 7C will not slide against each other even during operation. Therefore, the contact portion between the inner side of the bearing 7c and the crankshaft 6a maintains the form of a sliding bearing.

Still another embodiment will be described with reference to FIG. FIG. 3 shows a horizontal hermetic scroll compressor. In this embodiment, the crankshaft 6 is supported by bearings 7a and 7C arranged on both sides of the motor 10, and an oil supply pipe 44 is provided on the end face of the shaft, and lubricating oil 26 is supplied from each oil supply hole in the shaft 6. It is designed to be supplied to a sliding bearing 7. Further, the back pressure chamber 5 has a pressure between the suction pressure and the discharge pressure due to the intermediate pressure hole 19, and in particular, the lubricating oil after being used for lubrication of the bearings 7a and 7b is discharged into the back pressure chamber 5. , flows into the compression working chamber from the intermediate pressure hole 19, etc., is discharged from the discharge hole 13, and returns to the original oil reservoir. On the other hand, suction gas is sucked in from the suction boat 23, and high-pressure gas is discharged from the discharge port 13. This high pressure gas flows out into the cycle piping (not shown) of the air conditioner through the discharge pipe 24 shown on the right side of FIG.

Especially in a compressor configured in this way, the self-aligning bearing 7
The installation of c is very important, and can prevent uneven bearing contact and support the crankshaft so that the clearance between the stator 10a and the rotor 10b is always maintained at an optimum level.

〔Effect of the invention〕

According to the present invention, an assembly error occurs during compressor assembly;
Even if the center of the crankshaft 6 and the center of the closed container 16 are slightly misaligned, the self-aligning action of the bearing 7C can maintain a suitable bearing condition without uneven contact, so the bearing lubrication condition This has the effect of improving the reliability of each bearing, reducing friction loss occurring in the bearing, and improving the energy efficiency of the entire compressor.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the entire compressor showing one embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the entire compressor showing another embodiment, and FIG. 3 is a further another embodiment. FIG. 2 is a sectional view of the compressor. 1...Fixed scroll, 2...Orbiting scroll, 3
...Frame, 6...Crankshaft, 7c...
Lower bearing, 8... Oldham ring, 10... motor,
16...Casing, 21...Lower bearing housing,
23... Inlet, complete drawing j1 Otsu et al. 13 Fig. 2 helmet 3 O

Claims (1)

[Claims] 1. A fixed scroll having a spiral wrap on its end plate;
an orbiting scroll consisting of a wrap and an end plate that engage with the spiral wrap; an anti-rotation member that prevents rotation of the orbiting scroll; a crankshaft that causes the orbiting scroll to revolve on a circular orbit; In a hermetic scroll compressor formed by housing a frame supporting the crankshaft and an electric element in a sealed container, bearings that pivotally support the crankshaft are disposed on both sides of the motor, and one of the bearings is connected to the crankshaft. A plain bearing with a self-aligning function that matches the inclination of the shaft, or
A hermetic scroll compressor, characterized in that the outer peripheral part of the bearing is a sliding bearing having a spherical shape, the bearing support is provided separately from the bottom casing of the hermetic container, and is configured to be supported by the casing body.