Screw compressor with sliding bearings

Abstract

A screw compressor with sliding bearings includes a female rotor and a male rotor; a suction end-face of the male rotor and suction and exhaust end-faces of the female rotor are respectively provided with recessed holes, in which radial sliding bearings are arranged and matched with suction and exhaust side projecting shafts embedded; a thrust sliding bearing is arranged on an end-face of the suction side projecting shaft; passages are connected to the recessed holes are provided in the female and male rotors along the axis direction, and radial passages are provided to connect axial passages and rotor chamber. Using sliding bearings inside the rotors can simplify compressor structure and reduce occupied space and cost. Besides, the passages provided inside rotors simplify the liquid return structure of sliding bearings while cool the rotors, reduce the thermal deformation of the rotors, and improve the reliability and performance of the compressor.

Description

BACKGROUND OF THE PRESENT INVENTION

Field of Invention

The present invention relates to a field of screw compressors, and more particularly to a screw compressor with sliding bearings.

Description of Related Arts

The screw compressor generally has a body, a helical male and a female rotor engaged with each other and arranged in parallel in the body, namely screw rotors. The male rotor and the female rotor need to be supported by the bearings mounted in the body, so that projecting shafts are generally provided on both sides of the female and male rotors and fitted to the bearings.

Conventionally, there has been another screw compressor of the different structure. The screw compressor is not provided with projecting shafts on the end-faces of the female and male rotors to mount the bearing, but recessed holes are drilled on the suction end-faces and the exhaust end-faces of the male rotor and the female rotor respectively. The recessed holes are provided as bearing chambers and rolling bearings are disposed in the bearing chambers to support the screw rotors. For example, Japanese patent JP-7-279868 disclosed a screw compressor having a configuration in which projecting shafts at the suction side and exhaust side of the body enter the rolling bearings in the recessed hole bearing chambers of the male rotor and the female rotor respectively. The male and female rotors are supported by these rolling bearings.

Screw compressors are widely used in various industrial sectors such as refrigeration, power, chemical, machinery, etc., and have a high market share. However, the cost of screw compressors is high, which limits the expansion of the market share of screw compressors. Screw compressors generally use rolling bearings to support the screw rotors, but the cost of the rolling bearing is high, and it is not suitable for a screw compressor in which the bearing lubricant and injected medium into the compressor are the same liquid. In addition, in the case of a screw compressor where the screw rotor temperature is high, such as a water vapor screw compressor, the deformation of the screw rotor is large, and it is easy to cause the female and male rotors to be stuck. In order to prevent the female and male rotors from being stuck, a large meshing clearance and a large exhaust end-face clearance are generally provided, resulting in a decrease in the performance of the screw compressor. Therefore, it is necessary to reduce the temperature of the screw rotor and the deformation of the screw rotor, thereby increasing the performance of the screw compressor.

SUMMARY OF THE PRESENT INVENTION

In order to reduce compressor production costs and solve the problem of large deformation of screw rotors on the condition of high exhaust temperature, the present invention provides a screw compressor with sliding bearings.

Accordingly, in order to accomplish the above objects, the present invention provides:

A screw compressor with sliding bearings, comprising: a body, screw rotors, and a sliding support structure for supporting the screw rotors in the body, wherein recessed holes are provided on suction end-faces or/and exhaust end-faces of the screw rotors; the sliding support structure comprises radial sliding bearings which are arranged in the recessed holes and coaxially rotates with the screw rotors; or the sliding bearing structure has the recessed holes as bearing bushes of the radial sliding bearings; body projecting shafts fitted with the radial sliding bearings are arranged on the suction side or/and the exhaust side of the body, and the body projecting shafts and the radial sliding bearings form radial gaps at fitting positions; the radial gaps are connected to a lubricant inlet disposed on the body; passages are provided inside the screw rotors, and rotor chamber between the screw rotors and the body is connected to the recessed holes through the passages; lubricant enters the rotor chamber through the passages after lubricating the radial sliding bearings.

Preferably, liquid supply grooves respectively are connected the radial gaps and the lubricant inlet are disposed on the projecting shafts of the body.

Preferably, the sliding support structure comprises a radial sliding bearing at suction side of the male rotor, a radial sliding bearing at suction side of the female rotor and a sliding bearing at exhaust side of the female rotor, wherein the recessed holes for fixing the radial sliding bearings are provided on the suction end-face of the male rotor, the suction end-face and the exhaust end-face of the female rotor, or the suction end-face of the male rotor, the suction end-face and the exhaust end-face of the female rotor have the recessed holes as the bearing bushes of the radial sliding bearings; the body projecting shafts matching with the radial sliding bearings are respectively arranged on the suction side and the exhaust side of the body.

Preferably, the sliding support structure further comprises thrust sliding bearings (comprising a thrust sliding bearing at suction side of the male rotor and a thrust sliding bearing at suction side of the female rotor) disposed in the recessed holes on the suction end-faces of the screw rotors (comprising a female rotor and a male rotor), and the thrust sliding bearings match with thrust faces at bottoms of the recessed holes where the thrust sliding bearings are disposed; both the thrust faces and the thrust sliding bearings together bear axial force of the screw rotors.

Preferably, the thrust sliding bearings are connected to end-faces of the corresponding body projecting shafts, or the thrust sliding bearings are directly processed on the end-faces of the body projecting shafts.

Preferably, the passage comprises axial passages connected to the corresponding recessed holes in the male rotor and the female rotor of the screw compressor, and radial passages disposed in the male rotor and the female rotor of the screw compressor; wherein one end of the radial passages is connected to the axial passages, and the other end of the radial passages is connected to the rotor chamber.

Preferably, the number of the radial passages is determined by lubrication and sealing requirements in the rotor chamber, and positions of the radial passages towards the rotor chamber are determined by the injection flow rate through the radial passages; the axial passages are connected to bottoms of the recessed holes and extends along male and female rotor axes.

Preferably, the sliding support structure further comprises a radial sliding bearing, which matches with one end of the male rotor of the screw compressor which extends out of the body, and is fixed to the exhaust side of the body.

Beneficial effects of the present invention are as follows.

The present invention simplifies the structure of the screw compressor and reduces the manufacturing cost of the screw compressor by providing the radial sliding bearings in the recessed holes at the end-faces of the screw rotors or directly using the recessed holes as the bearing bushes of the radial sliding bearings. The present invention provides a passage structure in the screw rotors, which can be used as a cooling duct of the screw rotors, as a lubricant return passage of the sliding bearings, and as a injection pipe to the rotor chamber. The combination of various functions such as cooling, lubrication, sealing and lowering noise not only avoids the large meshing clearance and large exhaust end-face gap, but also improves the performance of the compressor.

Furthermore, the present invention provides the recessed holes on the end-faces of the male rotor and the female rotor, wherein the recessed holes are fitted with bearing bushes of the radial sliding bearings or are directly provided as the bearing bushes of the radial sliding bearings, and the projecting shaft on the suction side of the body is connected with the thrust sliding bearings or the thrust sliding bearings are directly processed on the end-faces. As a result, no rolling bearings are used to support the rotors, which simplifies the structure of the compressor, improves the bearing capacity of the bearings, and reduces the space occupied by the compressor and the cost. Especially, the present invention is suitable for occasions where space is limited.

Furthermore, the present invention simplifies the liquid return structure of the sliding bearings by providing the axial and radial passages in the male rotor and the female rotor as the return passages of the sliding bearing lubricant. At the same time, the passages can cool the rotors, reduce the thermal deformation of the rotors, so as to prevent the rotors from being stuck in a given gap and improve the reliability of the screw compressor.

Furthermore, the radial passage provided in the male rotor and the female rotor of the present invention is equivalent to an injection pipe to the rotor chamber, which can cool the compression medium, lubricate the rotors and seal the rotor chamber, so as to improve the performance of the screw compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram of a screw compressor using sliding bearings according to embodiment 1;

FIG. 2 is a structural diagram of a screw compressor using sliding bearings according to embodiment 2;

Element references: 1—suction end cap; 2—cylinder body; 3—radial sliding bearing at suction side of male rotor; 4—thrust sliding bearing at suction side of male rotor; 5—male rotor; 6—exhaust end cap; 7—radial sliding bearing at exhaust side of male rotor; 8—seal; 9—female rotor; 10—radial sliding bearing at exhaust side of female rotor; 11—radial passage in rotors; 12—axial passage in rotors; 13—thrust face in rotors; 14—thrust sliding bearing at suction side of female rotor; 15—radial sliding bearing at suction side of female rotor; 16—body axial passages; 17—body radial passages; 18—liquid supply groove of sliding bearing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be further described below in conjunction with the drawings and embodiments. The following embodiments are intended to illustrate the present invention instead of limiting it.

Embodiment 1

Referring to FIG. 1, a screw compressor comprises a body, screw rotors (comprising a female rotor 9 and a male rotor 5 arranged in parallel and engaged with each other), a radial sliding bearing at the suction side of the male rotor 3, a thrust sliding bearing at the suction side of the male rotor 4, a radial sliding bearing at exhaust side of male rotor 7, a radial sliding bearing at the suction side of the female rotor 15, a thrust sliding bearing at the suction side of the female rotor 14, and a radial sliding bearing at the exhaust side of the female rotor 10. The body comprises a cylinder body 2, and a suction end cap 1 and an exhaust end cap 6 which are respectively arranged at the suction side and the exhaust side, and connected to the cylinder body 2. A projecting shaft exists on the exhaust end-face of the male rotor 5 and extends out of the body. Recessed holes are provided at the suction end-face of the male rotor 5, the suction end-face and the exhaust end-face of the female rotor 9 to fix radial sliding bearings (i.e. the radial sliding bearing at the suction side of the male rotor 3, the radial sliding bearing at the suction side of the female rotor 15 and the radial sliding bearing at the exhaust side of the female rotor 10). A body projecting shaft at suction side and a body projecting shaft at the exhaust side are provided on internal side faces of the suction end cap 1 and the exhaust end cap 6 to match with radial sliding bearings in corresponding recessed holes, wherein the end-face of the body projecting shaft at the suction side is provided with thrust sliding bearings (i.e. the thrust sliding bearing at the suction side of the male rotor 4 and the thrust sliding bearing at the suction side of the female rotor 14, which are not contacted with the radial sliding bearing in the same recessed hole) but match with the thrust face (i.e. thrust face in rotors 13) at bottoms of corresponding recessed holes. Axial passages in rotors 12 connected to the recessed holes are provided inside the female rotor 9 and the male rotor 5 respectively along axial directions, and radial passages in rotors 11 are provided in radial directions, wherein the radial passages in rotors 11 is connected to the axial passages in rotors 12 and extends to the rotor chamber.

The body projecting shafts are provided with liquid supply grooves of sliding bearings 18, where body radial passages 17 are set in the body projecting shafts. Body axial passages 16 are inwardly provided from external faces of the suction end cap 1 and the exhaust end cap 6, and are connected to the body radial passages 17. The liquid supply grooves of sliding bearings 18, the body radial passages 17 and the body axial passages 16 integrally all together serve as a lubricant supply line for the sliding bearings. Clean, high-pressure and low-temperature lubricant enters corresponding radial sliding bearing clearances (i.e. radial gaps between bearing bushes and the body projecting shafts) through the supply line. After lubricating the radial sliding bearings, part of the lubricant enters the rotor chamber through suction and exhaust end gaps of rotors, and the other part flows through the thrust sliding bearings (or directly) to enter the axial passages in rotors 12 and the radial passages in rotors 11 through the thrust faces, and finally enters the rotor chamber. All of the lubricant eventually is discharged out of the compressor through the discharge port along with the compression medium.

The exhaust end cap 6 is provided with bearing chambers, and the projecting shaft on the male rotor matches with the radial sliding bearing at the exhaust side of the male rotor 7 disposed in the bearing chamber. The bearing chamber is provided with a liquid inlet hole (lubricant inlet) for the lubricant to enter the bearing chamber of the radial sliding bearing at the exhaust side of the male rotor 7 through the liquid inlet hole, and to enter the gap of the radial sliding bearing through the gap between the seal 8 and the bearing bush of the radial sliding bearing at the exhaust side of the male rotor 7. After lubricating the radial sliding bearing, the lubricant enters the rotor chamber through the exhaust end gap of the male rotor or another pipeline.

Embodiment 2

Referring to FIG. 2, compared with the embodiment 1, a screw compressor of the embodiment 2 omits the radial sliding bearing at the suction side of the male rotor 3, the thrust sliding bearing at the suction side of the male rotor 4, the radial sliding bearing at the exhaust side of the female rotor 10, the thrust sliding bearing at the suction side of the female rotor 14 and the radial sliding bearing at the suction side of the female rotor 15. In the embodiment 2, the recessed holes on the suction end-faces of the female and male rotors directly serve as bearing bushes of the radial sliding bearings and match with the body projecting shaft at the suction side. The thrust sliding bearing is directly processed on the end-faces of the body projecting shaft at the suction side, which works with the bottom faces of the recessed holes (the thrust faces). The recessed hole on the exhaust end-face of the female rotor is also directly used as bearing bushes of the radial sliding bearing and match with the body projecting shaft at the exhaust side. In summary, the screw compressor disclosed in the present invention adopts the radial sliding bearings and the thrust sliding bearings in the female and male rotors, and does not need to use a rolling bearing structure to support the rotors, which simplifies the structure of the compressor and reduces space occupied by the compressor and cost. Especially, the present invention is suitable for occasions where space is limited. In addition, since the cooling and lubrication passages (i.e. the axial passages and radial passages in rotors) connected to the lubrication passages of sliding bearings (i.e. the lubricant supply lines) is provided in the male rotor and the female rotor, the liquid return structure of the sliding bearings is further simplified. At the same time, it can cool the rotor, reduce the thermal deformation of the rotor, so as to prevent the rotor from being stuck in a given gap and improve the reliability of the screw compressor. Finally, the cooling lubrication passages in the male rotor and the female rotor are equivalent to increasing the injection passages to the rotor chamber, and can cool the compression medium, lubricate the rotors and seal the rotor chamber, so as to improve the performance of the screw compressor.

The present invention is applicable to all screw compressors in which the bearing lubricant and the injection medium of the compressor are the same liquid, such as oil-injected screw compressor, water-lubricated screw air compressor, water-lubricated steam screw compressor, refrigerant-lubricated refrigeration compressor, liquid process medium cooled and lubricated process gas compressor, etc.

Claims

1. A screw compressor with sliding bearings, comprising: a body, screw rotors, and a sliding support structure for supporting the screw rotors in the body, wherein the sliding support structure comprises radial sliding bearings which are arranged in recessed holes on suction end-faces or/and exhaust end-faces of the screw rotors and coaxially rotate with the screw rotors; or the sliding bearing structure has the recessed holes, as bearing bushes of the radial sliding bearings, located on the suction end-faces or/and the exhaust end faces of the screw rotors; body projecting shafts fitted with the radial sliding bearings are arranged on a suction side or/and an exhaust side of the body, and the body projecting shafts and the radial sliding bearings form radial gaps at fitting positions; the radial gaps are connected to a lubricant inlet disposed on the body; passages are provided inside the screw rotors, and a rotor chamber between the screw rotors and the body is connected to the recessed holes through the passages.

2. The screw compressor, as recited in claim 1, wherein liquid supply grooves respectively connecting the radial gaps and the lubricant inlet are disposed on the projecting shafts of the body.

3. The screw compressor, as recited in claim 1, wherein the sliding support structure comprises a radial sliding bearing at a suction side of a male rotor (3), a radial sliding bearing at a suction side of a female rotor (15) and a radial sliding bearing at an exhaust side of the female rotor (10), wherein the recessed holes for fixing the radial sliding bearings are provided on a suction end-face of the male rotor, a suction end-face and a exhaust end-face of the female rotor in the screw compressor, or the suction end-face of the male rotor, the suction end-face and the exhaust end-face of the female rotor have the recessed holes as the bearing bushes of the radial sliding bearings; the body projecting shafts matching with the radial sliding bearings are respectively arranged on the suction side and the exhaust side of the body.

4. The screw compressor, as recited in claim 1, wherein the sliding support structure further comprises thrust sliding bearings disposed in the recessed holes on the suction end-faces of the screw rotors, and the thrust sliding bearings match with thrust faces at bottoms of the recessed holes where the thrust sliding bearings are disposed.

5. The screw compressor, as recited in claim 4, wherein the thrust sliding bearings are connected to end-faces of the corresponding body projecting shafts, or the thrust sliding bearings are directly processed on the end-faces of the body projecting shafts.

6. The screw compressor, as recited in claim 1, wherein the passage comprises axial passages connected to the corresponding recessed holes in a male rotor and a female rotor of the screw compressor, and radial passages disposed in the male rotor and the female rotor of the screw compressor; wherein one end of the radial passages is connected to the axial passages, and the other end of the radial passages is connected to the rotor chamber.

7. The screw compressor, as recited in claim 6, wherein a number of the radial passages is determined by lubrication and sealing requirements in the rotor chamber, and positions of the radial passages towards the rotor chamber are determined by a injection flow rate through the radial passages; the axial passages are connected to bottoms of the recessed holes and extend along axes.

8. The screw compressor, as recited in claim 1, wherein the sliding support structure further comprises a radial sliding bearing, which matches with one end of a male rotor of the screw compressor which extends out of the body, and is fixed to the exhaust side of the body.