US20120258003A1

US20120258003A1 - Scroll compressor with spring to assist in holding scroll wraps in contact

Info

Publication number: US20120258003A1
Application number: US13/080,703
Authority: US
Inventors: Gregory W. Hahn
Original assignee: Individual
Current assignee: Danfoss Scroll Technologies LLC
Priority date: 2011-04-06
Filing date: 2011-04-06
Publication date: 2012-10-11
Also published as: CN102734156A; DE102012003002A1; CN102734156B

Abstract

An electric motor drives a shaft to cause one scroll member to orbit relative to another scroll member. The shaft has an eccentric pin extending upwardly into a slider block. The eccentric pin is further provided with a generally flat drive surface, with clearance provided between the bore of the slider block and an outer periphery of the eccentric pin such that the slider block can move relative to the eccentric pin. The slider block extends upwardly into a boss extending away from the base of one scroll member wrap. A spring is positioned to bias the one scroll wrap toward the other scroll member wrap. The spring is positioned between the eccentric pin and the bore of the slider block.

Description

BACKGROUND

This application relates to a scroll compressor wherein a spring is provided between an eccentric pin and an associated slider block, and biases the scroll wraps into contact together.
Scroll compressors are known, and are widely utilized in refrigerant compression applications. In a standard scroll compressor, a first scroll member has a base and a generally spiral wrap extending from its base. The first scroll member interfits with a second scroll member also having a spiral wrap extending from its base. The second scroll member is caused to orbit relative to the first scroll member, and as this orbiting movement occurs, an entrapped refrigerant is compressed toward a discharge port.
When the scroll compressor is driven to orbit, a centrifugal force is provided by the orbiting movement. It is known to provide a counterweight to counteract this centrifugal force. Typically, the counterweight has been provided on a driveshaft for the orbiting scroll. However, more recently, counterweights have been incorporated into a drive connection between the driveshaft and orbiting scroll.
In one known type of drive connection, an eccentric pin extends away from a driveshaft which is driven by a motor. The pin extends into a bore of a slider block. The slider block is typically provided with a generally circular bore, and a generally flat face which is contacted by a mating generally flat face of the eccentric pin. However, there is movement allowed between the eccentric pin and the slider block, by having the bore of the slider block be larger than the outer periphery of the eccentric pin. This movement allows the two scroll wraps to move out of contact with each other when compression of liquid is attempted and mechanically protects the scrolls by controlling the maximum forces from ingestion of liquid.
When the orbiting scroll is being driven, the centrifugal force has generally caused the slider block to move in a direction which holds the scroll compressor wraps in contact. If the wraps move out of contact, then there will be a leak, and compression efficiency will be hurt.
The use of the counterweight at the drive connection, and in particular about the slider block acts to counteract this centrifugal force.
It has been proposed to have a drive surface between the eccentric pin and the slider block be at an angle which is non-parallel to a center of the counterweight. In this way, a drive force is generated which tends to hold the scroll wraps in contact. At lower speed, this drive force can still hold the wraps in contact, however, as speed increases, the drive force may not be sufficient.

SUMMARY

A scroll compressor has a first scroll member having a base and a generally spiral wrap extending from said base, and a second scroll member having a base and a generally spiral wrap extending from its base. The wraps interfit to define compression chambers. An electric motor drives a shaft to cause the second scroll member to orbit relative to the first scroll member. The shaft has an eccentric pin extending upwardly into a slider block, which is provided with a bore with a generally flat drive surface, and a curved surface at locations removed from the generally flat drive surface. The eccentric pin is further provided with a generally flat drive surface, with clearance provided between the bore of the slider block and an outer periphery of the eccentric pin such that the slider block can move relative to the eccentric pin. The slider block extends upwardly into a boss extending away from the base of said second scroll member, with movement of the slider block relative to the eccentric pin causing movement of the second scroll wrap member relative to the first scroll member. A spring is positioned to bias the second scroll wrap toward a wrap of the first scroll member. The spring is positioned between the eccentric pin and the bore of the slider block.
These and other features of the present invention can be best understood from the following specification and drawings, of which the following is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a scroll compressor.

FIG. 2 shows a detail of a drive connection in a scroll compressor.

FIG. 3 shows another embodiment.

FIG. 4 shows yet another embodiment.

FIG. 5 shows a view of the FIG. 4 embodiment.

DETAILED DESCRIPTION

A compressor 20 is illustrated in FIG. 1 having a drive motor 122 driving a shaft 24. Shaft 24 is provided with an eccentric pin 26. A slider block 28 has a bore surrounding the eccentric pin 26. As is known, the slider block and pin each have a generally cylindrical section over a good deal of circumferential extent of the two. However, a relatively flat drive face is formed on both the eccentric pin and the slider block over a limited circumferential extent. These two relatively flat drive surfaces are brought into contact to cause an orbiting scroll member 21 to orbit relative to a non-orbiting scroll member 22. In addition, a non-rotating coupling, such as an Oldham coupling, may be positioned to cause the orbiting movement, as known. While the term “flat faces” have been utilized to describe surfaces on the eccentric pin and slider block, in practice, there may be a slight curve or barrel shape to one or both, and the term “flat” should be interpreted with this in mind.
A counterweight 30 surrounds the slider block 28. As shown, a cylindrical ring 36 on the counterweight 30 surrounds the slider block 28, and an extending portion 34 extends upwardly such that it circumferentially surrounds a boss 32 that receives the slider block 28 and eccentric pin 26. As shown, a hydrodynamic oil bearing 400 is positioned intermediate the inner periphery of the boss 32, and the outer periphery of the slider block 28.
As is well known in scroll compressors, refrigerant to be compressed enters the compressor 20 through a suction tube 160, and flows into a suction pressure chamber 101 surrounding the motor 122. That refrigerant passes upwardly into compression chambers 105 formed between the scroll members, and is compressed and delivered into a discharge pressure chamber 102. From the discharge pressure chamber 102, the refrigerant flows outwardly through a tube 103.
As shown in FIG. 2, counterweight 30 surrounds the slider block 28. There is a flat drive face 62 on the interior bore 60 of the slider block 28. The outer periphery of the eccentric pin 26 is shown, and can be seen to have a mating drive face 99. As shown, the outer periphery of the eccentric pin 26 also has a cylindrical portion 98 at locations spaced from the flat drive surface 99. Similarly, there is a cylindrical portion 61 forming part of the bore 60 of the slider block 28.
The inner periphery of the bore of cylindrical ring 36 of the counterweight may be provided with a flat as may be the outer periphery of the slider block. This will ensure proper positioning of the counterweight on the slider block.
As is clear from FIG. 2, the bore within the slider block is larger than the outer periphery of the eccentric pin such that some movement is allowed. This movement allows the scroll wraps to move out of contact in certain conditions.
As shown, a centerline of the counterweight is generally aligned with a centrifugal force. The force from the drive angle provided by surfaces 62 and 99 is along line Fda. The force of the counterweight C acts in opposition to the centrifugal force, and thus limits the force holding the scroll members in contact. The angle A increases the holding force to help hold the scroll members in contact. In practice, this angle A is non-zero and may be between 6° and 40°, and more particularly between 5° and 20°, and more particularly, between 6° and 20°. In one embodiment, the angle was between 7.5° and 17.5°.
By having this relationship between the flat drive surface 62 and the counterweight center axis, better control of the operation of the scroll compressor is achieved. The angle provides extra closing force, and better control to hold the wraps in contact during compression. The centrifugal force created by the moving elements has a part in holding the wraps in contact, and the use of the counterweight will somewhat limit that centrifugal force. As such, this angle provides additional force. On the one hand, if the angle is too small, there may not be enough force, but excessive force would also be undesirable. As such, the mentioned ranges provide valuable benefits.
In this application, a spring 208 has been added into the bore of the slider block 28, and has an end which is positioned in a notch at the end of the flat surface 62, and an opposed end in notch 212. As can be appreciated, the ends of the spring are snapped into indentations in the bore 60 of the slider block 28. There may be a plurality of these springs positioned into the plane of this Figure. The leaf springs serve to bias the slider block 28 and counterweight 30 generally upwardly as shown in FIG. 2. This will further serve to hold the compressor wraps in contact.
The use of the spring provides a holding force that is able to withstand even high speed operation to maintain the scroll wraps in reliable contact, and preserve the efficient operation of the scroll compressor.
In addition, as is clear, a clearance 220 exists between the spring 208, and a surface 221 which forms part of the bore in the slider block 28. The space for receiving the spring is not a continuation of the cylindrical portion 61.
FIG. 3 shows another embodiment slider block 300. As shown here, the flat drive face 302 would not be at an angle as is found in the FIG. 2 embodiment, but generally parallel with the centerline of a counterweight as shown in FIG. 2. In the embodiment 300, notches 304 and 306 receive a pair of leaf springs 308 and 310. While a counterweight is utilized in FIG. 2, and may be utilized in FIG. 3, it is also possible that a counterweight be located elsewhere with this embodiment.
FIG. 4 shows another embodiment slider block 230. Again, the flat drive face 231 may be generally parallel with the centerline of a counterweight as shown in FIG. 2. This embodiment could be used with or without a counterweight located about the slider block. Notches 232 and 234 are shown receiving a plurality of springs 236, 238, 240, and 242.
FIG. 5 shows the slider block 230 sitting about an eccentric pin 229. The springs 236, 238, 240, and 242 can be seen to be biasing the slider block 230 generally to the right as shown in this Figure, and thus also moving the orbiting scroll member boss 32 generally to the right. This will hold the wraps in contact, as described above. While this view is shown only to the FIG. 4 embodiment, a similar location would be true of the FIGS. 2 and 3 embodiments also.
Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.

Claims

1. A scroll compressor comprising:

a first scroll member having a base and a generally spiral wrap extending from said base;

a second scroll member having a base and a generally spiral wrap extending from its base, said wraps of said first and second scroll members interfitting to define compression chambers;

an electric motor driving a shaft to cause said second scroll member to orbit relative to said first scroll member, and said shaft having an eccentric pin extending upwardly into a slider block, said slider block being provided with a bore with a generally flat drive surface, and a curved surface at locations removed from said generally flat drive surface, said eccentric pin further being provided with a generally flat drive surface, with clearance provided between said bore of said slider block and an outer periphery of said eccentric pin such that said slider block can move relative to said eccentric pin;

said slider block extending upwardly into a boss extending away from said base of said second scroll member, with movement of said slider block relative to said eccentric pin causing movement of said second scroll member relative to said first scroll member; and

a spring biasing said second scroll member wrap toward said first scroll member wrap, said spring being positioned between said eccentric pin and said bore of said slider block.

2. The scroll compressor as set forth in claim 1, wherein said spring is a leaf spring.

3. The scroll compressor as set forth in claim 2, wherein said leaf spring is positioned within said bore of said slider block, and within said curved portion.

4. The scroll compressor as set forth in claim 3, wherein one end of said leaf spring is formed adjacent an end of said flat drive surface.

5. The scroll compressor as set forth in claim 4, wherein said flat drive face of said slider block is formed along a line which is non-parallel to a center line of said counterweight.

6. The scroll compressor as set forth in claim 4, wherein said flat drive face of said slider block is formed to be parallel to a centerline of a counterweight received about said slider block.

7. The scroll compressor as set forth in claim 1, wherein there are a plurality of springs.

8. The scroll compressor as set forth in claim 7, wherein there are at least four leaf springs.

9. The scroll compressor as set forth in claim 1, wherein a face of said spring facing an inner periphery of said slider block bore is spaced from said slider block bore.