JP2563438Y2 - Screw pump rotor / shaft coupling structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a screw pump for gas pressure feeding.

(Prior Art) Roots blower having a screw-shaped rotor and a means for fixing the rotor and the shaft by press-fitting a shaft having a spline and a cylindrical guide into a stepped hole of the rotor,
Japanese Patent Application Laid-Open No. 60-11695 discloses that a roots blower rotor and a shaft are press-fitted by similar means, and a stopper pin is provided near the center of the rotor to penetrate the rotor and the shaft in the diameter direction. The thing is shown in Jitsuhei 1-21192.

(Issues to be solved by the invention) Gas pumps become hot due to friction and compression of gas.
The clearance between adjacent members also changes due to the difference in expansion. In the blower disclosed in Japanese Patent Application Laid-Open No. 60-11695, means for actively preventing the rotor from being displaced in the axial direction with respect to the shaft is not used. The airtightness is likely to decrease due to the occurrence of a gap or a change in the clearance between the rotor end face and the inner surface of the housing, and the pump efficiency is also likely to decrease.

In addition, since the connection is made by a relatively shallow spline, there is a problem that a large connection strength cannot be obtained.

In addition, the roots blower of Japanese Utility Model No. 1-21922 is connected with a retaining pin at the center of the rotor,
The dimensional change due to thermal expansion is divided into left and right, and the clearance changes equally between the left and right. For a roots blower that does not have a pressure difference in the axial direction, there is no problem.However, if this coupling means is used for a screw pump with a pressure difference, leakage from the high-pressure discharge side will be large and the efficiency will decrease. become.

Therefore, an object of the present invention is to improve the disadvantages of these conventional techniques.

(Means for Solving the Problems) The means for solving the above problems in the present invention is to provide a large-diameter hole on the discharge side serving as a high-pressure part of the pump and a suction side serving as a low-pressure part through the center of a screw rotor made of light metal. A stepped hole having a small-diameter hole is formed in the rotor, and a single shaft having a spline press-fitted into the large-diameter hole and a guide portion fitted into the small-diameter hole is press-fitted into the stepped hole. And a shaft, and a spline connecting portion is provided with a fixing pin which penetrates the rotor and the shaft in the diametrical direction and regulates the axial movement of the rotor during extension and contraction.

(Operation) Since the above means are provided, the distance from the fixing pin to the discharge side end face of the rotor is short, and the dimensional change is small even if expansion due to temperature rise occurs. Therefore, the clearance between the discharge side housing inner surface and the rotor end face changes. do not do. Therefore, the clearance can be set to a minimum to minimize leakage from the high pressure side. The retaining pin also serves to transmit torque, and also serves to reinforce the spline portion. (Embodiment) Hereinafter, an embodiment in which the present invention is applied to a supercharger A of an engine will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a gear case of the supercharger A, on one side of which a light metal housing 3 of a screw pump 2 is connected by bolts 4 and, on the other side, an input shaft 5 is supported therethrough. A pulley 6 driven by an engine via a belt is provided at an outer end of the input shaft 5.
, And a drive gear 8 is mounted in the gear case 1.

Screw-shaped male and female rotors 10 and 11 made of light metal are supported in the housing 3 in a meshing manner. The shafts 12 and 13 are made of steel and have a side wall 14 of the gear case 1 and a side wall 15 of the housing. , Are supported by bearings 16, 17, 18, and 19 mounted on. Timing gears 20 and 21 are fixedly engaged with portions of the shafts 12 and 13 projecting into the gear case.
A pinion 22 is fixed to an end portion of the drive gear 12 and is driven at an increased speed by meshing with the drive gear 8.

The two rotors 10, 11 are driven by timing gears 20, 21 in the direction of the arrow shown at the right end, and the intake air is provided on both sides or the back side of the end faces of the rotors 10, 11 in contact with the side wall 18. It is introduced into the screw groove from the suction port (not shown) as indicated by the dotted arrow 23, is carried to the front side along with the rotation of both rotors 10, 11, and the screw starts meshing, and the meshing position moves from the right side to the left side. It moves and is discharged from a discharge port (not shown) provided on the surface near the side wall 14 as shown by a solid line arrow 24 and supplied to the intake side of the engine.

The means for fixing the rotor and the shaft will be described with reference to FIG. 2 with respect to the male rotor 10 and the shaft 12. The rotor 10 is provided with a stepped hole 25 having a large diameter on the discharge port side of the pump and a small diameter on the suction port side. details l _1, l _2, the large-diameter hole 26 having a length of l _3, middle-diameter hole 27, the small-diameter hole 28 are sequentially formed.

On the other hand, the shaft 12 has a spline 30 from the discharge port side, a small-diameter intermediate portion 31, a guide portion 32 slightly larger in diameter than the intermediate portion 31 and pressed into the small-diameter hole 28, a tapered portion 33 for facilitating insertion, The support portions 34 are sequentially formed, a ring groove is cut in the middle of the support portions 34, a Teflon ring 35 is fitted, and the support portion 34 is fitted to the inner race of the bearing 18 via the Teflon ring 35.
The Teflon ring 35 is for improving the sliding of the bearing 18 with respect to the shaft 12 when the housing 3 expands and contracts with respect to the shaft 12 due to a difference in the amount of expansion.

The shaft 12 is assembled to the rotor 10 by using the large-diameter hole
This is performed by press-fitting the guide portion 32 side of the shaft 12 from the 26 side. When the guide portion 32 enters the small-diameter hole 28, the straightness of the shaft 12 is ensured, and when the shaft 12 is further pushed in, the spline 30 increases the size. A spline groove is formed in the inner surface of the diameter hole 26 and spline-coupled, and the guide portion 32 and the small diameter hole 28 are tightly fitted to integrate the two members. Further, a pin hole is bored through the spline connection portion in the diameter direction, and a fixing pin 36 is press-fitted into the pin hole as shown in FIG. 3 to prevent the relative movement of the two members in the axial direction. And a torque transmission action is performed together with the spline.

The above-mentioned fixing means is the same for the female rotor 11 and the shaft 13, and the two shafts 12, 13 to which the rotor is assembled are arranged such that the bearings 16, 17 are held between the thrust rings 37, 38 and the timing gears 20, 21. Is attached to the gear case 1 to prevent axial movement.
Relative movement with 19 is possible. Clearance C ₁ between the end face 39 and the side wall 14 of the discharge side of the rotor 10 shown in FIG. 2 in this state the high pressure gas of a very small discharge side is prevented from leaking to the back side through the clearance C _1.

Even each part has a thermal expansion by increasing the operating in the temperature, the discharge side clearance change C ₁ is hardly no airtightness change for near fixing pin 36 is sidewall 14, the thermal expansion of the rotor suction side Escaped to Clearance C ₂ is changed because this time the housing 3 is also thermally expanded, the initial clearance are then sized to avoid interference during reduction. However, in the suction side does not occur practically without hindrance, such leakage is as pressure difference less since high pressure on the discharge side be greater clearance C ₂ is the outside.

(Effects of the Invention) As described above, in the present invention, since the rotor and the shaft are spline-coupled on the discharge side of the pump and the spline portion is pin-coupled, the relative movement between the rotor and the shaft on the spline press-fit coupling portion side is reduced. Thus, there is no possibility that the coupling portion is maintained in the initial engagement state and rattling occurs. In addition, since the thermal expansion of the rotor is released to the suction side and the clearance between the discharge side end face and the housing side wall can be maintained constant regardless of the temperature change, the clearance can be set to be extremely small, and leakage of high pressure gas on the discharge side can be prevented. This has the effect of minimizing the pump efficiency and preventing a decrease in pump efficiency. Further, since the fixing pin also serves as a torque transmitting member together with the spline, it has the effect of reducing the load on the spline and increasing the durability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a turbocharger embodying the present invention, FIG. 2 is a longitudinal sectional view showing a fitted state of a rotor and a shaft, and FIG. 3 is III in FIG. FIG. 3 is a sectional view taken along line III. 2. Screw pump 3. Housing 10, 11 ... Rotor 12, 13 ... Shaft 14, 15 ... Side wall 25 ... Stepped hole 26 ... Large diameter hole 28 ... Small diameter hole 30 ... Spline 32 ... Guide part 36 ... Fixed pin

Claims (1)

(57) [Scope of request for utility model registration] 1. A stepped hole having a large-diameter hole on a discharge side serving as a high-pressure part and a small-diameter hole on a suction side serving as a low-pressure part is formed through the center of a light metal screw rotor. One shaft having a spline press-fitted into the large-diameter hole and a guide portion fitted into the small-diameter hole is press-fitted into the stepped hole to couple the rotor and the shaft of the screw pump. A screw-rotor-shaft coupling structure, characterized in that a fixing pin that penetrates in a diametric direction and regulates axial movement of the rotor during expansion and contraction is provided.