JPH06280765A - Shim thickness measuring method for screw type pump - Google Patents

Abstract

PURPOSE:To perform reliable prevention of contact of a rotor with a cover body owing to thermal expansion of a rotor by a method wherein a given amount of a gap is ensured at the narrowmost part of a gap even when a gap between the end face of the rotor and the inner surface of the cover body is made uneven owing to a processing error. CONSTITUTION:A screw type supercharger is formed such that a rotor 2 contained in a housing 1 is supported to a bearing 4, attached to the cover body 3 of the housing, on a stepped shaft 5 protruded from the end face of the rotor. In the screw type supercharger, the thickness (t) of a shim 11 located between the stepped part 5c of the stepped shaft and the inner end face of the bearing is calculated from a hole depth L2 from the shaft length L1 of the large part 5b of the stepped shaft and the inner surface of the cover body to the inner end face of the bearing so that a given gap CL is ensured between the end face of the rotor and the end face of the cover body. The shaft length L1 is measured as an axial direction between the axial outermost spot of the end face of the rotor and the stepped part 5c and the hole depth is measured as an axial distance between the axial innermost sport of the inner surface of the cover body and the inner end face of the bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting the thickness of a shim incorporated in a screw type pump used in an engine supercharger or the like.

[0002]

2. Description of the Related Art A screw type pump used as a supercharger for an engine has a housing 1 with a single screw as shown in FIG.
A pair of bearings 4 and 4 are attached to a lid 3 that houses a pair of rotors 2 and 2 and is attached to the open end of the housing 1, and each bearing is provided on a stepped shaft 5 that projects each rotor 2 on its end surface. 4, a gear cover 6 is attached to the outer surface of the lid body 3, and a drive shaft 7 driven by an engine via a pulley 7a is installed in the cover 6 and the drive shaft 7 is provided.
A timing gear, in which a driven gear 8 ₂ that meshes with the upper drive gear 8 ₁ is attached to the stepped shaft 5 of one rotor 2 and the stepped shaft 5 and the stepped shaft 5 of the other rotor 2 mesh with each other. 8 ₃ and 8 ₃ are attached, both rotors 2 and 2 are rotated by the power from the engine, and air is compressed from the intake port on the end wall side of the housing 1 to the air supply port on the lid 3 side to supply air. Is configured. Reference numeral 9 in the figure denotes a gear fixing nut screwed to the outer end of the stepped shaft 5, and the rotor 2 uses the gear collar 10 that comes into contact with the outer end surface of the bearing 4 as the reaction force is received by the rotor 2 when the nut 9 is tightened. It is designed to be attracted to the 3rd side.

By the way, the rotor 2 is generally made of an aluminum-based material for weight reduction. However, since aluminum has a large coefficient of thermal expansion, the rotor 2 is thermally expanded by the heat generated by the compression of air, and It is possible that the end surface of 2 may come into contact with the end surface of the lid body 3, and thus the end surface of FIG.
As clearly shown in (b), a shim 11 is provided between the small-diameter portion 5a of the stepped shaft 5 fitted to the bearing 4 and the stepped portion 5c of the large-diameter portion 5b and the inner end surface of the bearing 4, and the rotor 2 A predetermined gap is secured between the end surface of the cover and the inner surface of the lid 3. The length CL of the gap is defined by the axial length of the large diameter portion 5b of the stepped shaft 5 being L1, the hole depth between the inner surface of the lid 3 and the inner end surface of the bearing 4 being L2, and the thickness of the shim 11. As t, CL = L1 + t−L2. Thus, by measuring L1 and L2, it is possible to calculate the shim thickness t required to bring CL to a predetermined value.

[0004]

By the way, the end surface of the rotor may be slightly inclined from the surface perpendicular to the rotor axis due to machining error or the like. Due to this inclination, the gap between the rotor end surface and the inner surface of the lid is not uniform. become. Therefore, if the shim thickness t is set by simply measuring the axial length L1 of the large-diameter portion, the gap becomes partially narrower than a predetermined value, and the rotor end surface in this portion causes the thermal expansion of the rotor to cause the inner surface of the lid to be closed. May come into contact with. In view of the above points, an object of the present invention is to provide a shim thickness setting method capable of preventing contact between the rotor end surface and the lid inner surface even if there is a processing error.

[0005]

[Means for Solving the Problems] In order to achieve the above object,
The present invention relates to a screw pump in which a bearing for supporting a fitting small axis portion on the outer end side of a stepped shaft protruding from the end face of a rotor housed in a housing is attached to a lid body attached to an open end of the housing. , The thickness of the shim provided between the stepped portion of the stepped shaft and the inner end surface of the bearing is set so that the end surface of the rotor faces the inner surface of the lid with a predetermined gap. A large diameter portion of the stepped shaft between the stepped portion of the stepped shaft and the stepped portion of the stepped shaft, and the hole depth between the inner surface of the lid and the inner end surface of the bearing. It is characterized in that the axial length of the portion is measured as the axial distance between the axially outermost portion of the end surface of the rotor and the stepped portion of the stepped shaft.

[0006]

[Function] Since the axial length of the large diameter portion of the stepped shaft is measured with reference to the axially outermost portion of the rotor end surface where the gap between the rotor end surface and the lid inner surface is the narrowest, the maximum gap The shim thickness can be set so that the length of the narrow portion becomes a predetermined value, and contact between the rotor end surface and the lid inner surface due to thermal expansion of the rotor does not occur. In this case, a collar having a predetermined thickness is inserted into the collar so that the large diameter portion of the stepped shaft is seated on the end surface of the rotor, and the stepped inspection tool is capable of inserting the small diameter portion of the stepped shaft. It is preferable that the shaft length is measured by seating on a stepped portion of the shaft and bringing a probe of a displacement gauge attached to the inspection tool into contact with the collar.
That is, by inserting the large diameter portion of the stepped shaft into the collar, the collar is seated at the axially outermost portion of the rotor end face while keeping the squareness with respect to the rotor axis, and the rotor end face is scanned over the entire surface. Even if the axially outermost portion is not detected, the axial distance between the portion and the step portion can be measured.

Although the squareness of the inner surface of the lid with respect to the bearing axis may be deviated due to a processing error, the hole depth may be the axially inward portion of the inner surface of the lid facing the rotor and the inner end surface of the bearing. If it is measured as an axial distance between the and, it is possible to deal with a processing error on the inner surface of the lid. in this case,
A small diameter portion of a stepped shaft-shaped inspection tool is fitted into the bearing so that the stepped portion of the inspection tool abuts the inner end surface of the bearing, and a collar of a predetermined thickness is attached to the collar to increase the diameter of the inspection tool. If the portion is fitted and seated on the inner surface of the lid, and the probe of the displacement meter attached to the inspection tool is brought into contact with the collar and the hole depth is measured, the same as the measurement of the axial length described above. Even if the collar is seated at the innermost axial position on the inner surface of the lid while keeping the right angle to the bearing axis, and the inner surface of the lid is scanned over the entire surface without detecting the innermost axial position. The axial distance between the point and the inner end surface of the bearing can be measured.

[0008]

EXAMPLE An example to which the present invention is applied as a method for setting the thickness t of the shim 11 of the screw type pump shown in FIG. 1 will be described. FIG. 2 shows a process of measuring the axial length L1 of the large diameter portion 5b of the stepped shaft 5, and as shown in FIG. 2A, the large diameter portion 5b of the stepped shaft 5 is fitted to the collar 20 having a predetermined thickness. Then, the collar 20 is seated on the end face of the rotor 2, and further, the inspection tool 21 into which the small diameter portion of the stepped shaft 5 can be inserted is seated on the stepped portion 5c of the stepped shaft 5 and attached to the inspection tool 21. Measuring element 22 of displacement meter 22
The measurement is performed by bringing a into contact with the collar 20. Before this measurement, as shown in FIG. 2B, the display adjustment of the displacement gauge 22 is performed using the master shaft 23. The master shaft 23 is
A stepped shaft having a large-diameter portion 23b having a predetermined length L1s is projectingly provided on the substrate 23a, and the collar 2 is provided on the substrate 23a.
0 is seated, the inspection tool 21 is seated on the stepped portion at the upper end of the large diameter portion 23b, and in this state, the contact point 22a of the displacement meter 22 is brought into contact with the collar 20. The display is adjusted so that the displayed value becomes the length L1s of the large diameter portion 22b. Thus, the display value of the displacement gauge 22 in the state of FIG. 2A represents the axial distance from the bottom surface of the collar 20 to the step portion 5c of the stepped shaft 5.

By the way, the collar 20 is to be seated on the end face of the rotor 2 while maintaining a right angle with respect to the rotor axis by the large diameter portion 5b of the stepped shaft 5 fitted therein, and the end face is shown in FIG. 2 (a). Even if it is inclined with respect to the rotor axis as indicated by the line a or has an uneven surface as indicated by the line b, it is perpendicular to the rotor axis including the axially outermost portion (the uppermost portion in the figure) of the end face. The bottom surface of the collar 20 is located on the flat surface. As a result, the axial distance between the axially outermost portion of the end surface of the rotor 2 and the step portion 5c of the stepped shaft 5 is displayed by the displacement meter 22, and this value is displayed as the large diameter portion 5b of the stepped shaft 5. It is recorded as the axial length L1 of.

FIG. 3 shows a step of measuring the hole depth L2 between the inner surface of the lid body 3 and the inner end surface of the bearing 4, and as shown in FIG. On the inner surface, seat a collar 30 having a predetermined thickness, which is approximately the same as the outer diameter of the rotor 2,
The stepped shaft-shaped inspection tool 31 is inserted into the mounting hole of the bearing 4 so that the small diameter portion 31a is fitted in the bearing 4 and the large diameter portion 31b is fitted in the collar 30, and a screw projectingly provided on the outer end of the small diameter portion 31a. The nut 31e is tightened on the portion 31d so as to abut the outer end surface of the bearing 4, and the step portion 31c of the inspection tool 31 is brought into pressure contact with the inner end surface of the bearing 4, and the probe 32a of the displacement meter 32 attached to the inspection tool 31 is attached. The collar 30 is brought into contact with and measured. Prior to this measurement, as shown in FIG. 3B, the master lid 3 having a recess 33a having a predetermined depth L2s is formed.
3, the collar 30 is seated, and the inspection tool 31
The large-diameter portion 31b of the displacement gauge 32 is fitted into the collar 30 and inserted into the recessed hole 33a, and the step portion 31c of the inspection tool 31 is seated on the bottom surface of the recessed hole 33a. The display is adjusted so that the display value of the displacement meter 32 at this time becomes the hole depth L2s of the concave hole 33a. Thus, the display value of the displacement gauge 32 in the state of FIG. 3A represents the axial distance from the bottom surface of the collar 30 to the inner end surface of the bearing 4.

Here, the collar 30 is to be seated on the inner surface of the lid body 3 while maintaining the right angle with respect to the bearing axis by the large diameter portion 31b of the inspection tool 31 which is fitted therein, and the inner surface is shown in FIG. ) Is inclined with respect to the bearing axis as shown by the line a or has an uneven surface like the line b, the inner surface portion of the lid 3 facing the collar 30 (this portion is also the portion facing the rotor 2). The bottom surface of the collar 30 is located on a plane that is perpendicular to the bearing axis including the innermost portion in the axial direction (the uppermost portion in the drawing). As a result, the axial distance between the axially innermost portion of the inner surface portion of the lid body 3 facing the rotor 2 and the inner end surface of the bearing 4 is displayed by the displacement meter 32, and this value is set as the hole depth L2. Record.

When measuring the axial length L1, the collar 2 is used.
0 tilts by a small angle due to the fitting clearance for the large diameter portion 5b of the stepped shaft 5, and when measuring the hole depth L2, the collar 30 has a small angle due to the fitting clearance for the large diameter portion 31b of the inspection tool 31. There is a possibility of tilting, and in order not to cause an error due to this tilting, the inspection tools 21 and 31 are rotated once and the measuring elements 22a and 32a of the displacement gauges 22 and 32 make the outer diameter of the rotor 2 on the collars 20 and 30. It is desirable to scan one round along substantially the same circumference and set the minimum display value during that period as the measured values of L1 and L2.

After measuring the axial length L1 and the hole depth L2 as described above, CLs is the required value of the gap between the end surface of the rotor 2 and the inner surface of the lid 3, and the thickness t of the shim 11 is set. Is calculated by the following equation: t = CLs + L2-L1.

If the shim 11 having the thickness t is provided between the step portion 5c of the stepped shaft 5 and the inner end surface of the bearing 4, the rotor axis line of the end surface of the rotor 2 or the inner surface of the lid body 3 is caused by a processing error. Even if the squareness with respect to the deviation occurs, the required amount CLs is obtained in the narrowest part of the gap between the end surface of the rotor 2 and the inner surface of the lid 3.
Thus, the problem that the end surface of the rotor 2 comes into contact with the inner surface of the lid 3 due to the thermal expansion of the rotor 2 is reliably prevented.

[0015]

As is apparent from the above description, according to the present invention, even if the gap between the rotor end face and the lid end face becomes non-uniform due to a processing error, the required amount at the narrowest portion of the gap is required. The shim thickness can be set so as to secure the clearance of, and contact between the rotor end surface and the inner surface of the lid due to thermal expansion of the rotor can be reliably avoided.

[Brief description of drawings]

FIG. 1A is a cutaway side view of a screw type pump, and FIG. 1B is an enlarged cutaway side view of a main part thereof.

2A is a diagram showing a process of measuring an axial length according to the present invention, and FIG. 2B is a diagram showing a process of adjusting a display of a displacement meter.

3A is a diagram showing a hole depth measuring process according to the present invention, and FIG. 3B is a diagram showing a display adjusting process of a displacement meter.

[Explanation of symbols]

1 Housing 2 Rotor 3 Lid 4 Bearing 5 Stepped Shaft 5a Small Diameter 5b Large Diameter 5c Step 11
Shim 20,30 Color 21,31 Inspection tool 22,
32 displacement gauge 22a, 32a probe

Claims (4)

[Claims] 1. A screw type pump comprising a bearing mounted to an opening end of a housing, and a bearing for supporting a fitting small axis portion on an outer end side of a stepped shaft projecting from an end surface of a rotor housed in the housing. The shim thickness provided between the stepped portion of the stepped shaft and the inner end surface of the bearing so that the end surface of the rotor faces the inner surface of the lid body with a predetermined gap.
In the method of setting based on the axial length of the large diameter portion of the stepped shaft between the end surface of the rotor and the stepped portion of the stepped shaft, and the hole depth between the inner surface of the lid and the inner end surface of the bearing, A shim thickness setting method in a screw pump, wherein the axial length of the large diameter portion is measured as an axial distance between an axially outermost portion of an end surface of a rotor and a stepped portion of a stepped shaft. 2. The shaft length is measured by inserting a collar of a predetermined thickness into the collar with a large diameter portion of the stepped shaft seated on an end surface of the rotor and fitting a small diameter portion of the stepped shaft. The screw type according to claim 1, wherein an insertable test tool is seated on a stepped portion of the stepped shaft, and a probe of a displacement gauge attached to the test tool is brought into contact with the collar. How to set shim thickness in pump. 3. The hole depth is measured as an axial distance between an axially innermost portion of an inner surface portion of the lid body facing the rotor and an inner end surface of the bearing. The shim thickness setting method in the screw pump according to 1 or 2. 4. The measurement of the hole depth is performed by fitting a small-diameter portion of a stepped shaft-shaped inspection tool into the bearing to bring the stepped portion of the inspection tool into contact with the inner end surface of the bearing and at a predetermined time. A thick collar is inserted into the large diameter portion of the inspection tool to be seated on the inner surface of the lid, and a stylus of a displacement gauge attached to the inspection tool is brought into contact with the collar. The shim thickness setting method in the screw type pump according to claim 3.