JPH06280772A - Rotor and manufacture thereof - Google Patents

Abstract

PURPOSE:To facilitate a press-in work and to improve press-in precision, in the rotor of a screw pump formed such that a rotor shaft is pressed in the central hole of a rotor body for coupling. CONSTITUTION:In a rotor comprising a rotor body 1; and a rotor shaft 2 pressed in the central shaft hole 4 of the rotor body 1 for coupling, metal plating of Sn and the like for reducing a press-in frictional force is previously applied on the press-fit part 13 of the r6tor shaft 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor such as a screw rotor of a screw pump for a supercharger of an internal combustion engine and a method for manufacturing the rotor.

[0002]

2. Description of the Related Art Conventionally, a male and a female screw rotor of a screw pump used for a supercharger of an internal combustion engine has a rotor body and a rotor shaft which are separated from each other in order to secure required strength and reduce weight. The body, that is, the rotor body is
Made of light alloy such as alloy, the rotor shaft is made of steel, the rotor shaft is press-fitted into the central shaft hole drilled in the rotor body, and the rotor body and rotor shaft are fixed to pin holes that penetrate them in the diameter direction. A structure in which a pin is press-fitted is already known (see Japanese Utility Model Publication No. 4-47190).

[0003]

By the way, in such a screw pump, in order to prevent metal contact between the rotors or between the rotor and the housing and improve their airtightness, a fixed lubricant is applied to the outer surface of each rotor body. It is generally practiced to prevent direct contact between metals by coating a resin film as a film. By the way, in the case of manufacturing each screw rotor by forming the rotor body and the rotor shaft as separate bodies and connecting them by a fixing pin as described in the above publication, the following manufacturing method is adopted. Become. Ie. The rotor shaft is press-fitted into the central shaft hole of the rotor body.

.. A pin hole is drilled to extend over the rotor body and the rotor shaft.

.. A fixing pin is press-fitted into the pin hole.

[0006] After finishing the machining of
After degreasing, the outer surface of the rotor body is coated with a resin film as a fixed lubricant film.

However, in such a manufacturing method, since the rotor body is drilled and the rotor shaft and the fixing pin are press-fitted before the coating of the resin film, the cutting oil and the drilling oil during the drilling process are used. When the rotor shaft and fixing pin are press-fitted, the outer surface of the rotor body is coated with a resin film of relatively high temperature while the air remains in the rotor body. There is an inconvenience that it leaks from the central shaft hole and the pin hole to hinder the coating of the resin film.

[0008] Therefore, in order to eliminate the conventional inconvenience,
The applicant of the present invention press-fits the rotor shaft into the central shaft hole of the rotor body, and the fixing pin into the pin hole extending over the rotor body and the rotor shaft with a large tightening margin in an airtight manner, and leaves them inside the rotor. A new technique has been proposed in which expanded cutting oil, air, etc. are prevented from leaking to the outside of the rotor so that the resin film can be favorably coated (see Japanese Utility Model Laid-Open No. 4-121488).

However, it has turned out that such a new technique also has problems. That is, when the rotor shaft is press-fitted into the central shaft hole of the rotor body in an airtight manner, an excessive pressurizing force is applied to the rotor shaft in the axial direction, which not only increases the press-fitting cost but also increases the rotor shaft. May be deformed or the surface may be damaged, and when the fixing pin is press-fitted into the pin hole that extends between the rotor body and the rotor shaft, the fixing pin should be supported with both ends of the rotor shaft supported. Since the press-fitting work is performed by excessively pressing the pin hole, the rotor shaft may be bent and deformed. In particular, when the pin hole is a dead end, the air compressed in the hole is generated. Since there is no escape area, there is a problem that the press-fitting force becomes more excessive and the flexural deformation of the rotor shaft becomes more remarkable.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel rotor and a method for manufacturing the same, which solves all of the above problems.

[0011]

In order to achieve the above-mentioned object, the first feature of the rotor of the present invention is that the rotor main body is provided with a central shaft hole, and the rotor is press-fitted into the central shaft hole. The rotor shaft has a press-fitting fitting portion (13) plated with metal for reducing press-fitting frictional force.

A second feature of the rotor of the present invention is that the rotor body is provided with a central shaft hole, and the rotor shaft is press-fitted into the central shaft hole. Is that a dead end bag-shaped pin hole extending in the radial direction is bored, and a hollow fixing pin having both ends opened is press-fitted into the pin hole.

Further, the rotor manufacturing method of the present invention is characterized in that a rotor body having a central shaft hole formed therein, a rotor shaft press-fitted into the central shaft hole, and the rotor body and the rotor shaft are provided with the rotor shaft. A rotor manufacturing method, comprising: a fixed pin having both ends opened, which is press-fitted into a dead end bag-shaped pin hole that is bored across in the radial direction, wherein the rotor shaft has an outer peripheral surface of the press-fitted portion. After metal plating, the step of dry press-fitting the rotor shaft into the central axis hole of the rotor body, the step of coating a resin coating on the outer surface of the rotor body, and the pin hole in the rotor body. Drilling and press-fitting and coupling the hollow fixing pin into the pin hole.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a male rotor of a screw pump will be described below with reference to FIGS.

FIG. 1 is a side view of a male rotor of a screw pump embodying the present invention, FIG. 2 is a cross-sectional view of the male rotor taken along line 2-2 of FIG. 1, and FIG. 3 is a side face of a rotor shaft. 4 and 5 are perspective views of the fixing pin.

The male rotor Rm of the screw pump is composed of a rotor body 1, a rotor shaft 2 and a fixing pin 3.

The rotor body 1 is made of a light alloy, that is, Al.
It is made of an alloy and has a central shaft hole 4 opened at both end faces at the center thereof. Further, a pin hole 5 is bored at one end of the rotor body 1 in the axial direction on the discharge side in the diametrical direction, that is, orthogonal to the central axis hole 4. This pin hole 5
Is formed in the shape of a dead end, and one end thereof is opened to the outer peripheral surface of the rotor body 1. Male screw teeth 6 are formed on the outer peripheral surface of the rotor body 1 as usual, and the open ends of the pin holes 6 are opened in the valleys of the male screw teeth 6 as shown in FIG. . The outer surface of the rotor body 1, that is, the outer peripheral surface on which the male screw teeth 6 are formed and both end surfaces thereof are coated with a resin film 7 as a fixed lubricant film, as described later.

On the other hand, the rotor shaft 2 is made of steel and is configured to penetrate through the central shaft hole 4 of the rotor body 1 and to be press-fitted and coupled thereto. The rotor shaft 2 has a discharge side journal shaft portion 8 from the discharge end side (the left end in FIG. 3), and this shaft portion 8
A seal receiving portion 9 having a diameter larger than that, a rotor body fitting portion 10 having a diameter slightly smaller than the seal receiving portion 9, a taper portion 11 for facilitating insertion, and a suction side journal having a diameter smaller than the discharge side journal shaft portion 8. The shaft portion 12 is sequentially formed.
The outer periphery of the end of the rotor main body fitting portion 10 adjacent to the suction side journal shaft portion 12 is metal-plated for reducing the press-fit frictional force, that is, Sn plating.
3 is formed. The press-fitting fitting portion 13 is formed to have a diameter slightly larger than that of the rotor body 1 so that the press-fitting fitting portion 13 can be press-fitted into the central shaft hole 4 of the rotor body 1 with a predetermined interference. It has a large diameter. The metal plating may also be applied to the tapered portion 11.

A pin hole 14 whose both ends are opened in the diametrical direction is formed in the rotor shaft fitting portion 10 of the rotor shaft 2 close to the seal receiving portion 9, that is, at the discharge side end.
When the rotor shaft 2 is press-fitted into the rotor body 1 as shown in FIG. 1, the pin holes 5 and 14 of the rotor body 1 straddle the rotor body 1 as described in detail later. Then, the fixing pin 3 is press-fitted.

The fixing pin 3 is made of steel and is formed of a hollow cylindrical body having both ends open as shown in FIG. Is also formed with a large diameter. Thus, the thickness of the fixing pin 3 is determined in consideration of the rotational balance of the male rotor Rm itself.

Next, the manufacturing process of the male rotor composed of the rotor body 1, the rotor shaft 2 and the fixing pin 3 as described above will be explained mainly with reference to FIG. 5. First, as shown in FIG. The press-fitting fitting portion 13 is formed by previously applying metal plating for reducing the press-fitting frictional force, that is, Sn plating, to the suction side end portion of the rotor body fitting portion 10 of the rotor shaft 2. Next, as shown in FIG. 5B, after the rotor body 1 is installed vertically on the pedestal 15, the rotor shaft 2 is inserted into the central shaft hole 4.
Is dry press-fitted from the suction end side, that is, the suction side journal shaft portion 12. At this time, since the press-fitting fitting portion 13 of the rotor shaft 2 is preliminarily plated with Sn, the press-fitting friction is reduced even though they are press-fitted in an airtight manner, and dry press-fitting work is performed. Not only it becomes easier, but also the bending due to the press-fitting load of the rotor shaft 2 can be prevented, and furthermore, the occurrence of galling between the central shaft hole 4 of the rotor body 1 and the rotor shaft 2 can be suppressed, and the press-fitting surface of those can be suppressed. It is possible to prevent scratches.

Next, as shown in FIG. 5C, the rotor body 1
After coating the resin film 7 as a solid lubricant film on the outer peripheral surface and both end surfaces of the rotor, both ends of the rotor shaft 2 of the male rotor Rm are supported by the supporting members 16 at both ends as shown in FIG. Dead end bag-shaped pin hole 5 and pin hole 1
4 is drilled with a drill 17, and finally Fig. 5 (e)
As shown in, the hollow cylindrical fixing pin 3 having both ends open is press-fitted to the pin holes 5 and 14. At this time, since the pin hole 5 is formed in a dead-end bag shape and the fixed pin 3 is formed in a hollow cylindrical shape with both ends open, residual air in the pin hole 5 passes through the fixed pin 3 to the outside. It is possible to significantly reduce the load (50% or less) compared to the case where the fixed pin that is released and has the same press-fitting margin is press-fitted. As a result, the press-fitting work becomes easier and the rotor shaft The bending stress applied to the rotor shaft 2 can be reduced to prevent the bending deformation of the rotor shaft 2.

As described above, the male rotor R coated with a good resin film that is free from bending and scratches, has a very high precision, and does not peel off by the press-fitting process shown in FIGS.
m can be produced.

6A and 6B show a modification of the fixing pin. The fixing pin 3 ₁ shown in FIG. 6 (A) has a single slit 18 formed along the generatrix direction of the hollow cylindrical body. According to this fixing pin 3 ₁ , the press-fitting load into the pin hole 5 is further improved. It can be reduced. The other fixed pins 3 ₂ is larger chamber or resonator chamber relatively volume inside the hollow cylindrical body 19 shown in FIG. 6 (B)
And the fixing pin 3 ₂
The resonator chamber 19 has a muffling function and helps reduce the operating noise of the screw pump.

In the above embodiment, the case where the screw pump is applied to the male rotor Rm has been described.
The female rotor Rf meshed with the male rotor Rm has the same structure as that of the male rotor Rm, that is, as shown in FIG.
The rotor shaft 102 is press-fitted and coupled into the central shaft hole 104, and the fixing pins 103 are further press-fitted and fitted in the radial direction thereof.
The female rotor Rf is also manufactured by the same method as the male rotor Rm.

7 to 9 show a screw pump used as a supercharger for an automobile, which is constructed as described above and incorporates the novel male and female screw rotors Rm and Rf.

The specific structure of this screw pump will be described below.

FIG. 7 is a vertical sectional side view of the supercharger, and FIG.
Is a partially enlarged view of the arrow 8 line in FIG. 7, and FIG. 9 is 9-9 in FIG.
It is sectional drawing which follows the line.

In FIG. 7, a split gear case 21 is integrally connected to one end of the pump housing 20. The pump housing 20 accommodates a pair of male and female screw rotors Rm, Rf having the above-described structure in a meshed state, and the rotor shafts 2, 1 of these rotors Rm, Rf are accommodated.
02, the suction side journal shaft portions 12 and 112 are rotatably supported on the wall portion of the pump housing 20 through bearings 22 and 122, and the discharge side journal shaft portions 8 and 1 thereof.
08 is rotatably supported on the wall portion of the gear case 21 via double row bearings 23 and 123. Also, the gear case 21
An input shaft 26 is rotatably supported by the bearings 24 and 25 on the drive shaft 27.
The male and female rotors Rm and Rf are interlocked and connected via a transmission gear group G including a driven gear 28 and timing gears 29 and 30. Further, at the outer end of the input shaft 26,
A drive pulley 31 is fixed, and the drive pulley 31 is connected to an internal combustion engine (not shown) via a transmission belt.
According to the drive of the internal combustion engine, the male and female rotors Rm, R are driven via the drive pulley 31 and the transmission gear group G.
f is driven to rotate synchronously, and the outside air is sucked into the pump housing 20 from the right end from the import as shown by the dotted line arrow I in FIG. 7 and is pressurized there from an unillustrated out port to the left end as shown by the dotted line arrow O in FIG. Is discharged to the outside.

By the way, in the double row bearings 23 and 123 for rotatably supporting the discharge end side journal shaft portions 8 and 108 of the male and female rotors Rm and Rf, their outer rings are the gear cases 21.
Are press-fitted to the rotor shafts 2 and 102 in the axial direction without play by preloading the inner rings of the connecting bolts 32 and 33 via the timing gears 29 and 30, respectively. It is tightly coupled. Therefore, the discharge-side journal shaft portions 8 and 108 of the male and female rotors Rm and Rf are the discharge-side double-row bearings 23 and 12, respectively.
It is movably supported in the axial direction by 3. The seal receiving portions 9 and 109 of the rotor shafts 2 and 102 are supported by the gear case 21 via seals 34 and 134, respectively.

On the other hand, the suction side bearings 22, 122 for rotatably supporting the suction side journal shaft portions 12, 112 of the male and female rotors Rm, Rf have their outer rings press-fitted to the pump housing 20 as shown in FIG. As shown in FIG. 8, the inner rings are elastically supported in an airtight manner on elastic rings 36, 36 made of synthetic resin rings bonded to the ring grooves 35, 35 provided in the journal shaft portions 12, 112. There is. These elastic rings 36, 36 have a rectangular cross section as shown in FIGS. 8 and 9, and are integrally injection-molded into the ring grooves 35, 35 having a flat portion on the bottom surface. The rotor shafts 2 and 102 are always rotated integrally with each other. The elastic rings 36, 36 may be bonded to the ring groove.

Thus, the suction side journal shaft portions 12, 112
The inner rings of the bearings 22, 122 of the elastic ring 36,
It is possible to move in the axial direction while making uniform contact with the upper surface of the screw shaft 36. Therefore, it is possible to absorb axial displacement due to thermal expansion of the rotor shafts 2 and 102, thereby eliminating axial play of the screw pump and making it impossible in the same direction. It can contribute to the improvement of pump performance without applying force.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment and various embodiments are possible within the scope of the present invention. For example, in the above embodiment, the case where the present invention is applied to the screw rotor has been described, but it is needless to say that the present invention can be applied to a roots rotor and other rotors, and in the above embodiment, the rotor body and the rotor shaft are fixed together. Although they are connected by pins, they may be connected by a plurality of fixed pins. Further, the fixed pin is set with the axial coupling position, the number, the length, the thickness, etc. of the rotor in consideration of the rotational balance of the rotor.

[0034]

As described above, according to the rotor of the present invention as set forth in claim 1, the rotor main body is provided with a central shaft hole, and the rotor shaft is press-fitted into the central shaft hole. Since the press-fitting fitting portion is plated with metal for press-fitting frictional force reduction, the frictional force of the press-fitting portion between the central shaft hole of the rotor body and the rotor shaft is significantly reduced by the metal plating. As a result, it is possible to reduce the press-fitting force applied to the rotor shaft, eliminate galling between them, prevent the rotor shaft from bending, and obtain a highly accurate rotor, and facilitate press-fitting work to reduce press-fitting cost. it can.

Further, according to the rotor of the present invention as defined in claim 2, the rotor main body is provided with a central shaft hole, and the rotor shaft is press-fitted into the central shaft hole. A dead end bag-shaped pin hole that spans the radial direction is bored, and a hollow fixing pin with both ends opened is press-fitted into this pin hole, so that the fixing pin extends across the rotor body and rotor shaft. When press-fitting, the air enclosed in the pin hole is easily discharged to the outside by the cooperation of the hollow fixing pin and the bag-shaped pin hole, and the press-in force of the fixing pin can be greatly reduced, and the rotor It is possible to prevent bending of the shaft, obtain a highly accurate rotor, and facilitate press-fitting work to reduce press-fitting cost. According to the rotor manufacturing method of the present invention as defined in claim 3,
A rotor body having a central shaft hole formed therein, a rotor shaft press-fitted into the central shaft hole, and a dead end bag-shaped pin hole formed in the rotor body and the rotor shaft in the radial direction thereof. A method of manufacturing a rotor having press-fitting fixed pins having both ends opened, wherein the rotor shaft is plated with metal on its outer peripheral surface, and then the rotor shaft is centered on the rotor body. Dry press-fitting connection to the shaft hole, coating a resin film on the outer surface of the rotor body, forming the pin hole in the rotor body, and press-fitting the hollow fixing pin into the pin hole. Since it includes the process and
Both the press-fitting of the rotor shaft into the rotor body and the press-fitting of the fixed pin into the pin hole extending over the rotor body and the rotor shaft can be performed with a pressure input that is as low as possible compared to the conventional pressure input. The press-fitting work efficiency can be greatly improved and the press-fitting accuracy can be improved.
In addition, the outer surface of the rotor body can be surely coated with a good resin coating.

[Brief description of drawings]

FIG. 1 is a side view of a male rotor of a screw pump embodying the present invention.

2 is a cross-sectional view of the male rotor taken along the line 2-2 in FIG.

FIG. 3 is a side view of the rotor shaft.

FIG. 4 is a perspective view of a fixing pin.

FIG. 5: Manufacturing process diagram of rotor

FIG. 6 is a perspective view of a modified example of a fixing pin.

FIG. 7 is an overall vertical sectional side view of a supercharger including the rotor of the present invention.

FIG. 8 is a partially enlarged view of arrow 8 in FIG.

9 is a sectional view taken along the line 9-9 of FIG.

[Explanation of symbols]

 1 Rotor Main Body 101 Rotor Main Body 2 Rotor Shaft 102 Rotor Shaft 3 Fixing Pin 103 Fixing Pin 4 Center Shaft 104 Center Shaft 5 Pin Hole 13 Press Fit Fitting 14 Pin Hole

Claims (3)

[Claims] 1. A rotor body (1,101) having a central shaft hole (4,104) formed therein, and a rotor shaft (2,102) press-fitted into the central shaft hole (4,104). , The press-fitting fitting portion (1
A rotor characterized in that 3) is plated with metal for reducing press-fit frictional force. 2. A rotor body (1,101) having a central shaft hole (4,104) formed therein, and a rotor shaft (2,102) press-fitted into the central shaft hole (4,104). , The rotor body (1, 101) and the rotor shaft (2, 102)
A dead end bag-shaped pin hole (5, 14) is pierced in the radial direction, and a hollow fixing pin (3, 103) having both ends opened is press-fitted into the pin hole (5, 14). A rotor characterized by being combined. 3. A rotor body (1, 101) having a central shaft hole (4, 104) formed therein, a rotor shaft (2, 102) press-fitted into the central shaft hole, and the rotor body (1, 101). 10
1) and the rotor shaft (2, 102), which are press-fitted into dead end bag-shaped pin holes (5, 14) that are formed in the rotor shaft (2, 102) in the radial direction thereof. 103)
A method of manufacturing a rotor comprising: a rotor shaft (2, 102), the outer peripheral surface of the press-fitting fitting portion (13) being plated with metal, Dry press-fitting and coupling to the central shaft hole (4, 104) of the rotor body (1, 101);
1) a step of coating the outer surface of the resin coating (7), and the rotor body (1, 101) with the pin hole (5, 5).
14), and press-fittingly coupling the hollow fixing pin (3, 103) into the pin hole (5, 14).