JPH08284673A - Screw type supercharger - Google Patents

Abstract

PURPOSE: To keep proper compression efficiency by reducing thermal expansion of a rotor per se, and securing minimum clearance in a compressor between the male and female rotors. CONSTITUTION: A male rotor 2 and a female rotor composed of spiral teeth mesed with each other for composing a compressor are fitted and fixed to a pair of parallel rotor shafts 2B which are synchronously rotated in opposite directions. The teeth 2A of the male rotor 2 are formed in a hollow manner. Air circulates through hollow portions 7D to 7F of the teeth 2A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw type supercharger installed in an intake system of an internal combustion engine. It can also be applied to various industrial screw compressors.

[0002]

2. Description of the Related Art A screw type supercharger of this type is provided with a male rotor and a female rotor which are composed of a plurality of spiral teeth that mesh with each other to form a compression portion by rotating in opposite directions synchronously. In order to avoid the adverse effect of the difference in thermal expansion of materials, each rotor is generally formed integrally with its rotor shaft.
However, when the cast iron integrated structure is adopted, the weight becomes large and it is not suitable for mounting on an automobile. Therefore, it has been proposed to reduce the weight by integrally molding the rotor and the rotor shaft with an aluminum alloy. As a result, it is lightweight and easy to process, but the aluminum rotor shaft cannot withstand high-speed rotation, and the rotor shaft only has to be made of iron. Therefore, due to the high heat during operation of the supercharger, the difference between the coefficient of thermal expansion of the rotor shaft made of iron and the coefficient of thermal expansion of the rotor made of aluminum alloy affects the thermal expansion in the male and female rotors with different wall thicknesses. However, the clearance of the compression part between the male and female rotors was deviated.

Therefore, in order to avoid the adverse effects of the combination of the rotors having different thermal expansion coefficients and the rotor shaft, the one disclosed in Japanese Utility Model Laid-Open No. 2-37286 as shown in FIG. 4 has been proposed. The conventional example will be briefly described below. The rotor bodies (teeth) 22A, 23A and the shafts 22B, 23 are described below.
A male rotor 22 and a female rotor 23, each of which has a male rotor 22 and a female rotor 23.
23A is made of a lightweight material such as an aluminum alloy, and the respective shafts 22B and 23B of the male rotor 22 and the female rotor 23 are formed.
Is made of a material having a linear expansion coefficient close to that of the material used for the rotor bodies 22A and 23A, and the rotor body 22A and the shaft 22B of the male rotor 22 and the rotor body 23A and the shaft 23B of the female rotor 23. Are integrally formed. Reference numeral 21 is a casing, 24
Indicates a suction port, and 25 indicates a discharge port. by this,
In addition to reducing the overall weight, the difference in thermal expansion between the rotor body and the shaft was eliminated to maintain an appropriate clearance between the male and female rotors.

[0004]

However, although the above-mentioned proposal has solved the adverse effect due to the difference in thermal expansion between the rotor body (tooth) and the rotor shaft to some extent, the high heat during operation of the supercharger causes It is unavoidable that the teeth themselves expand, and the delicate clearance of the compression part between the male and female rotors in the screw type turbocharger is still inconsistent, which tends to affect the compression efficiency (volumetric efficiency). Met. In the worst case, the male and female rotor teeth may come into contact with each other and the coating may peel off. Therefore, the present invention solves the problems in the conventional screw type supercharger, reduces the thermal expansion of the rotor teeth themselves, and secures the minimum gap in the compression portion between the male and female rotors to achieve an appropriate compression. Provide a screw type supercharger that can maintain efficiency.

[0005]

For this reason, the present invention is directed to spiral teeth that are fitted and fixed on a pair of parallel rotor shafts that rotate in opposite directions synchronously and that mesh with each other to form a compression portion. In a screw type supercharger including a male rotor and a female rotor, each tooth of the male rotor is formed hollow, and air is circulated in the hollow portion of the tooth. , Is a means for solving the problems. Further, according to the present invention, the hollow portion of each tooth has an opening portion on the suction port side, and in the vicinity of the other end surface, from the hollow portion of one tooth of the male rotor having at least three helical teeth to another. Is provided with an orifice that communicates with the hollow portion of the tooth, and an air intake fin is provided in the opening portion of the one tooth. This is a means for solving the problem. .

[0006]

Each tooth 2A of the hollow male rotor has openings 7A, 7B and 7C on the suction port side. When the rotor starts to rotate, one of these teeth has an opening 7A.
Part of the intake air near the air intake fin 8A provided in the air flows toward the other in the axial direction inside the hollow portion 7D of the tooth by the fin 8A, and is provided near the other end face.
Hollow part 7D of one tooth to hollow parts 7E, 7 of the other two teeth
After passing through the orifices 9A and 9B communicating with F, the hollow portions 7E and 7F of the other two teeth are circulated toward the openings 7B and 7C. In this way, the male rotor teeth forming the screw type supercharger are made hollow, and the male rotor teeth are cooled from the inside by circulating the air on the inlet side that is equal to the atmospheric temperature, and Even under high heat, the effects of thermal expansion on thick male rotor teeth can be significantly reduced, so even if the rotor shaft with high strength and the rotor teeth made of aluminum alloy are combined, those heat It is possible to maintain a proper compression efficiency by ensuring a minimum gap in the compression section between the male and female rotors without being particularly concerned with the difference in expansion coefficient. Further, by making the male rotor teeth hollow, it is possible to reduce the weight of the thick male rotor teeth. Furthermore, since the air intake fins 8A are provided in the opening 7A of one tooth that serves as an air intake, the forced circulation of the air becomes possible, and a higher cooling effect can be obtained. Further, by providing the orifice that communicates from the hollow portion of one tooth to the hollow portions of at least two other teeth, the volume of the forced circulation air passing through the orifice is expanded to approximately double and further cooled. , Its cooling effect is increased, which is extremely effective.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of a screw type supercharger of the present invention, FIG. 1 shows a male rotor as an essential part, and FIG. 2 shows an overall view of the screw type supercharger. As shown in FIG. 2, the screw type supercharger of the present invention includes a pair of parallel rotor shafts 2 which are synchronously rotated in opposite directions in a casing 1.
A male rotor 2 and a female rotor 3 each having at least three helical teeth that are fitted and fixed on B and 3B and mesh with each other to form a compressed portion. The driving torque from the input pulley 11, which is suspended around the engine crankshaft (not shown), is transmitted from the input gear 12 to the speed increasing gear 1.
3 is transmitted to a female timing gear 14 fixed to the female rotor shaft 3B and a male timing gear 15 fixed to the male rotor shaft 2B meshing with the gear 14. As a result, the male and female rotors 3 and 2 synchronously rotate in opposite directions. The rotor teeth of the male rotor 2 and the rotor teeth of the female rotor 3 mesh with each other to form a compression portion 6 in the axial direction. The air supplied from the supply path orthogonal to the paper surface flows in from the suction port 4, is compressed by the compression unit 6 and flows down in the axial direction, and is discharged from the discharge port 5 to the discharge path perpendicular to the paper surface.
Used for high-power combustion of the engine.

Next, the male rotor 2 of the first embodiment of the present invention will be described with reference to FIG. As described above, the rotor shaft 2B that rotates synchronously with the female rotor in opposite directions is made of an appropriate material having high strength. The same applies to the female rotor shaft, but the male rotor shaft 2B has its rotor teeth 2A.
Although it is desirable that the coefficient of thermal expansion be substantially the same, it is not necessarily limited to this. As shown in FIGS. 1B and 1D, on the rotor shaft 2B, a male rotor having at least three helical teeth that mesh with female rotor teeth (not shown) to form a compression portion. The teeth 2A are fitted and fixed by press fitting or the like. Each of the rotor teeth 2A has a hollow portion 7D, 7E, 7F (see FIG. 1C) therein and is formed hollow so that air circulates in the hollow portions 7D to 7F of the tooth 2A. It is configured. 1 (A) and (D)
As shown in FIG. 5, the hollow portions 7D to 7F of the teeth 2A have openings 7A, 7B and 7C on one end face (for example, the suction port 4 side of the supercharger) in the axial direction, and the other discharge port 5 Near the closed end face on the side, there are provided orifices 9A and 9B communicating from the hollow portion 7D of one tooth to the hollow portions 7E and 7F of at least two other teeth, and the opening portion 7A of the one tooth. The air intake fins 8 are provided in the. In addition,
Reference numeral 8B is a reinforcing fin provided on the inner surface on the outer peripheral side of each of the openings 7A, 7B, 7C. Further, the partition plate 10 for rectifying can be installed in the hollow portion 7D of one tooth, and if necessary, it can be extended in the radial direction to reinforce each tooth which is a hollow portion as the partition plate 10 and can be malely extended. It may be configured by connecting the boss portion and the outer peripheral portion of the rotor. Reference numeral 16 in FIG. 1 (D) denotes a pin embedded in the wall portion 17 of the male rotor 2 to close the hole for the skirting board provided for fixing the core when forming the mold of the male rotor 2. The end face of the male rotor 2 on the discharge port 5 side is closed by the pin 16 to form a wall portion, and the air compressed between the male and female rotors 3 and 2 is hollow portions 7D to 7F.
It is possible to prevent leakage from the inside and improve the volumetric efficiency.

When the screw type supercharger constituted by the male rotor 2 as described above is operated, a pair of the male rotor 2 and the female rotor 3 which rotate synchronously in opposite directions as shown in FIG. The portion 6 has a compressive action, and the rotation of the male rotor 2 causes the air in the vicinity of the air intake fins 8A provided in the opening 7A of one of the plurality of teeth of the male rotor 2 The air supplied for compression in the feeder is also used for cooling)
A flows in the hollow portion 7D of the tooth toward the other in the axial direction, and communicates from the hollow portion 7D of one tooth, which is bored near the other end face, to the hollow portions 7E and 7F of at least two other teeth. Through the orifices 9A and 9B which are used to circulate the hollow portions 7E and 7F of the other two teeth toward the openings 7B and 7C. Thus, the male rotor teeth that make up the screw type turbocharger are hollow and the air is circulated to cool the male rotor teeth from the inside. Since the effect of thermal expansion on the male rotor teeth can be significantly reduced, even with a combination of a rotor shaft of high strength and aluminum alloy rotor teeth,
Without being particularly concerned about the difference in their coefficient of thermal expansion,
The minimum gap in the compression section between the male and female rotors is secured, and proper compression efficiency can be maintained. Further, by making the male rotor teeth hollow, it is possible to reduce the weight of the thick male rotor teeth. In addition, one tooth opening 7 that serves as an air intake
Since the air intake fins 8A are provided in A, the forced circulation of air is enabled by this, and a higher cooling effect is obtained. Further, by providing the orifice that communicates from the hollow portion of one tooth to the hollow portions of at least two other teeth, the volume of the forced circulation air passing through the orifice is expanded to approximately double and further cooled. , Its cooling effect is increased, which is extremely effective.

FIG. 3 shows a second embodiment of the male rotor of the present invention. In this embodiment, the air intake provided in the opening 7A of one of the plurality of teeth of the male rotor 2 is taken in. Fin 8
As A, a sloping plate extending in the radial direction is formed across the boss portion and the outer peripheral portion of the hollow tooth, and other configurations are the same as those in the first embodiment. In this embodiment, the air intake fin 8A has a large area for air intake, and is excellent in the forced circulation ability of the cooling air.

The embodiments of the present invention have been described above.
Within the scope of the present invention, the cross-sectional shape of the hollow portion in the rotor tooth, the cooling air flow path shape, the number of orifices, the shape, the material of the rotor shaft and teeth, the number of teeth, the position of the suction port and the discharge port. It is needless to say that the fitting form of the rotor shaft and the rotor teeth, the method of synchronizing the male and female rotors, and the like can be appropriately selected. Also, the hollow part for cooling air in the rotor tooth may be formed so that both sides in the axial direction are open, and fins for forced circulation of air or orifices for increasing the cooling effect may be arranged. it can.

[0012]

As described above in detail, according to the present invention, the male rotor teeth are made hollow to circulate the air to cool the male rotor teeth from the inside, and the high heat during operation of the supercharger is obtained. Even if it is below, the effect of thermal expansion on thick male rotor teeth can be significantly reduced, and even if the rotor shaft with high strength and the rotor teeth made of aluminum alloy are combined, their thermal expansion coefficient It is possible to maintain a proper compression efficiency by ensuring a minimum gap in the compression section between the male and female rotors without being particularly concerned with the difference between the two. Further, by making the male rotor teeth hollow, it is possible to reduce the weight of the thick male rotor teeth. Furthermore, an air intake fin is provided at the opening of one tooth that serves as an air intake, whereby forced circulation of air is possible and a higher cooling effect is obtained. Furthermore, by providing an orifice that communicates from the hollow of one tooth to the hollow of at least two other teeth,
The forced circulation air passing through the orifice expands its volume almost twice and is further cooled, and its cooling effect is increased to be extremely effective.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a male rotor of a screw type supercharger of the present invention.

FIG. 2 is an overall view showing a screw type supercharger of the present invention.

FIG. 3 is a view showing a second embodiment of the male rotor of the screw type supercharger of the present invention.

FIG. 4 is a diagram of a conventional screw type supercharger.

[Explanation of symbols]

 2 Male rotor 2A Male rotor tooth 7A to 7C Opening 7D to 7F Hollow part 8A Air intake fin 9A, 9B Orifice

Claims (2)

[Claims] 1. A screw provided with a male rotor and a female rotor, each of which has spiral teeth that are fitted and fixed on a pair of parallel rotor shafts that rotate synchronously in mutually opposite directions and that mesh with each other to form a compression portion. A screw type supercharger, characterized in that each tooth of the male rotor is formed hollow and air is circulated in the hollow portion of the tooth. 2. The male rotor has at least three helical teeth, and the hollow portion of each tooth has an opening on the suction port side.
In the vicinity of the other end face, an orifice that communicates from the hollow portion of one tooth to the hollow portions of at least two other teeth is provided, and an air intake fin is provided at the opening portion of the one tooth. The screw type supercharger according to claim 1.