JP6014955B2 - Inner rotor of internal gear pump - Google Patents

Description

  The present invention relates to an inner rotor of an internal gear pump. More specifically, the present invention relates to an inner rotor of an internal gear pump in which a groove for fitting a drive shaft is formed at the periphery of the central hole of the inner rotor.

  For example, an internal gear pump is used to circulate and supply lubricating oil to an engine or transmission in an internal combustion engine. In such a gear pump, an outer rotor is disposed in a rotatable state in a pump casing, and an inner rotor having a rotation center eccentric from the center of the outer rotor is disposed on the inner diameter side of the outer rotor. . When the inner rotor is driven to rotate, the lubricating oil is sucked and discharged by meshing the outer teeth of the inner rotor and the inner teeth of the outer rotor.

  As a method for rotationally driving the inner rotor of such a gear pump, two or four grooves or notches are formed at equal intervals on the periphery of the central hole of the inner rotor, and these grooves extend from the drive shaft. There is a method of rotating the inner rotor by fitting the shafts that have been made and rotating the drive shaft.

  By the way, in the drive system using the groove | channel mentioned above, as shown in FIGS. 7-8, the center of the said inner rotor 21 and 31 is hold | maintained to the internal diameter side of the inner rotor 21 and 31 in which the groove | channels 20 and 30 were formed. Ring-shaped bushes 22 and 32 are press-fitted for fitting with the shaft. Due to the press-fitting of the bushes 22 and 32, a radially outward force is applied to the inner rotors 21 and 31, and the outer shape (the shape of the teeth 23 and 33) is deformed. However, in the conventional inner rotors 21 and 31, Since the number of teeth of 6 to 15 and the number of grooves (2 or 4) do not match, the deformation of the outer shape of the inner rotors 21 and 31 does not become a uniform deformation amount. The amount of deformation is small at a portion with 30 and the amount of deformation is large at a portion without the grooves 20 and 30. As a result, the roundness of the tooth tips 23a and 33a and the tooth bottoms 23b and 33b of the inner rotors 21 and 31 that should originally be perfect circles deteriorates, and abnormal noise is generated when meshing with the inner teeth of the outer rotor. May cause problems.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an inner rotor of an internal gear pump capable of preventing deterioration of roundness due to bush press-fitting.

(1) The inner rotor (hereinafter also simply referred to as “inner rotor”) of the internal gear pump of the present invention has a predetermined number of teeth formed on the outer periphery, and has a bush press-fitting hole in the center. An inner rotor of a tangential gear pump,
Along the periphery of the hole, the same number of grooves as the number of teeth are formed at equal intervals corresponding to the positions of the teeth ,
The width and depth of each groove are characterized by having the same value .

  In the inner rotor of the present invention, since the same number of grooves as the number of teeth of the inner rotor are formed at equal intervals along the peripheral edge of the central hole, the deformation amount of the outer shape (tooth shape) of the inner rotor is reduced. It can be made uniform in the circumferential direction. As a result, the meshing with the inner teeth of the outer rotor can be made smooth, and problems such as the generation of abnormal noise during meshing can be prevented.

(2) In the inner rotor of (1), the inner rotor is formed of a sintered body obtained by sintering a compact of iron-based metal powder, and the groove is formed corresponding to the tooth tip position. It may be. In this case, the minimum value of the radial distance (wall thickness) from the inner edge to the outer edge of the inner rotor can be increased as compared with the case of forming the groove corresponding to the tooth bottom, and the molded body is produced. Furthermore, the iron-based metal powder can be uniformly fed into the mold.

  According to the inner rotor of the present invention, it is possible to prevent deterioration of roundness due to bush press-fitting.

(A) is a top view of one Embodiment of the inner rotor of this invention, (b) is the sectional view on the AA line of the top view. (A) is a top view of the bush by which the inner rotor shown by FIG. 1 is inserted thickly, (b) is the BB sectional drawing. FIG. 3 is a plan view showing a state in which the bush shown in FIG. 2 is press-fitted into the inner rotor shown in FIG. 1. (A) is the top view of other embodiment of the inner rotor of this invention, (b) is CC sectional view taken on the line of the same top view. (A) is a top view of the bush by which the inner rotor shown by FIG. 4 is inserted thickly, (b) is the DD sectional view taken on the line. FIG. 6 is a plan view showing a state where the bush shown in FIG. 5 is press-fitted into the inner rotor shown in FIG. 4. It is a top view of the inner rotor which concerns on the comparative example 1 in which the bush was press-fitted. It is a top view of the inner rotor which concerns on the comparative example 2 in which the bush was press-fitted.

  Hereinafter, embodiments of the inner rotor of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1A is a plan view of an inner rotor 1 according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA of the plan view.

  The inner rotor 1 is a substantially disk-shaped member having a hole 2 in the center, and eight teeth 3 are formed on the outer periphery thereof at equal intervals in the circumferential direction. Further, on the periphery of the central hole 2, the same number of teeth 3, that is, eight grooves 4 are formed at equal intervals in the circumferential direction corresponding to the positions of the teeth 3. More specifically, the groove 4 is formed so that the center line in the circumferential direction of the groove 4 coincides with the center line in the circumferential direction of the tooth 3.

  The inner rotor 1 can be made of a metal material containing iron as a main component, but the inner rotor 1 in the present embodiment is a metal powder containing iron as a main component, specifically, for example, copper by weight ratio. A metal powder containing 1.5 to 6.0% of carbon, 0.2 to 1.0% of carbon, and the balance of iron is pressure-molded to produce a powder molded body. It is produced by sintering with a gas and a firing temperature, and subjecting the obtained sintered body to a heat treatment such as induction hardening and tempering.

  The groove 4 is a portion into which a shaft extending from a drive shaft (not shown) that rotationally drives the inner rotor 1 is inserted, and the width w and the depth d are appropriately selected according to the size of the shaft. For example, the width w may be 2 to 20 mm and the depth d may be 2 to 10 mm. In the present embodiment, the cross-sectional shapes of the eight grooves 4 are almost rectangular, and the width w and the depth d are the same value.

  For example, a ring-shaped bush 5 as shown in FIG. 2 is press-fitted into the inner diameter side of the inner rotor 1 in which the groove 4 is formed in order to fit with the shaft that holds the center of the inner rotor 1. . The bush 5 can be produced by, for example, winding a band-shaped plate material made of SPCC (cold rolled steel plate) in a ring shape and welding the joint.

  The press-fitting allowance when the bush 5 is press-fitted into the central hole 2 of the inner rotor 1 is not particularly limited in the present invention, but can be, for example, about 0.04 to 0.11 mm. FIG. 3 shows the inner rotor 1 after the bush press-fitting. Due to the press-fitting of the bush 5, a radially outward force is applied to the inner rotor 1 and its outer shape (the shape of the teeth 3) is deformed. In the present embodiment, along the periphery of the central hole 2, the inner rotor 1 is deformed. Since the same number of grooves 4 as the number of teeth of the rotor 1 are formed at equal intervals, the deformation amount of the outer shape (the shape of the teeth 3) of the inner rotor 1 can be made uniform in the circumferential direction. As a result, the meshing with the inner teeth of the outer rotor (not shown) can be made smooth, and problems such as the generation of abnormal noise during meshing can be prevented.

  Further, in the present embodiment, since the groove 4 is formed corresponding to the tooth tip position of the tooth 3 of the inner rotor 1, the inner rotor is compared with the case where the groove 4 is formed corresponding to the tooth bottom 6. The minimum value of the radial distance (thickness) from the inner edge to the outer edge can be increased. When producing a powder compact that is an intermediate product when producing the inner rotor 1, the iron-based metal powder is fed into the mold, and the feeding is performed evenly by eliminating a narrow space. be able to.

  FIG. 4 is a plan view and a cross-sectional view of an inner rotor 11 according to another embodiment of the present invention. Unlike the inner rotor 1 shown in FIG. 1 or FIG. 3, the inner rotor 11 has nine teeth 13 formed on the outer periphery at equal intervals in the circumferential direction. Further, the same number of grooves 14 as the number of teeth 13 are formed at equal intervals in the circumferential direction on the periphery of the central hole 12. Also in the present embodiment, the groove 14 is formed corresponding to the tooth tip position of the tooth 13.

  A bush 15 as shown in FIG. 5 is press-fitted into the central hole 2 of the inner rotor 11. FIG. 6 shows the inner rotor 11 after the bush press-fitting. Also in the inner rotor 11 shown in FIG. 4 or 6, the same number of grooves 14 as the number of teeth of the inner rotor 11 are formed at equal intervals along the peripheral edge of the central hole 12. The amount of deformation of the outer shape of 11 (the shape of the teeth 13) can be made uniform in the circumferential direction.

[Examples and Comparative Examples]
Next, the inner rotor of the present invention will be described based on examples, but the present invention is not limited to such examples.
<Example 1>
The bush (made of cold-rolled steel plate) shown in FIG. 2 was press-fitted into an 8-tooth inner rotor (iron metal powder sintered product) shown in FIG. The specifications of the inner rotor and bush were as follows. The press-fitting allowance was 0.07 mm.
Inner rotor tooth tip diameter Dt: 48.5 mm
Tooth root diameter Db: 37.0 mm
Thickness t: 10 mm
Groove width w: 4 mm
Groove depth d: 5 mm
Bush outer diameter: 18mm
Inner diameter: 13 mm
Height: 10mm

  In FIG. 3 showing the state after the press-fitting of the bush, the tip (tooth tip) of the uppermost position is No. No. 1 in the clockwise direction. No. 8 and the above No. The tooth root immediately adjacent to the tooth tip of No. 1 is also No. No. 1 in the clockwise direction. Number up to 8, and each No. The amount of deformation (mm) of the tooth tip and the tooth bottom was investigated using FEM analysis. The amount of change is the amount of change in the size in the radially outward direction (the distance from the center of the inner rotor to the tooth tip or the tooth bottom) due to the press-fitting of the bush. The results are shown in Table 1. In Table 1 and Tables 2 to 4 to be described later, “R” represents a difference between the maximum displacement amount and the minimum displacement amount.

<Comparative Example 1>
As shown in FIG. 7, the amount of deformation (mm) of the tooth tip and the root of the tooth is changed in the same manner as in Example 1 except that the number of grooves is four and the width of each groove is 8 mm which is twice the width of 4 mm. We investigated using analysis. The results are shown in Table 2.

<Example 2>
The bush (made of cold-rolled steel plate) shown in FIG. 5 was press-fitted into a 9-tooth inner rotor (iron metal powder sintered product) shown in FIG. The specifications of the inner rotor and bush were as follows. The press-fitting allowance was 0.07 mm.
Inner rotor tooth tip diameter Dt: 73mm
Tooth root diameter Db: 59 mm
Thickness t: 10 mm
Groove width w: 5 mm
Groove depth d: 5 mm
Bush outer diameter: 36mm
Inner diameter: 31 mm
Height: 10mm

  In FIG. 6 showing the state after the press-fitting of the bush, the tooth tip (tooth tip) at the uppermost position is No. No. 1 in the clockwise direction. No. 9 and the above No. 9 are assigned. The tooth root immediately adjacent to the tooth tip of No. 1 is also No. No. 1 in the clockwise direction. Number up to 9, and each No. The amount of deformation (mm) of the tooth tip and the tooth bottom was investigated using FEM analysis. The amount of change is the amount of change in size in the radially outward direction due to bush press-fitting. The results are shown in Table 3.

<Comparative Example 2>
As shown in FIG. 8, the amount of deformation of the tooth tip and the root is the same as in Example 2 except that the number of grooves is four and the width of each groove is 11.25 mm (5 mm × 9/4). (Mm) was investigated using FEM analysis. The results are shown in Table 4.

  As can be seen from Tables 1 to 4, by making the number of teeth and the number of grooves the same, the amount of deformation of the outer shape of the inner rotor after bush press-fitting can be made uniform in the circumferential direction. It is possible to prevent deterioration of the roundness of the tooth bottom. Of the comparative examples in which the number of grooves is 4 regardless of the number of teeth, in Comparative Example 1 in which the number of teeth is 8, the deformation amount of the root is uniform and the roundness is not deteriorated. The amount of deformation of the tooth tip without the groove was about twice that of the tooth tip with the groove. Further, in Comparative Example 2 where the number of teeth was 9, the amount of deformation was not uniform in the circumferential direction for both the tip and the root. For this reason, roundness deteriorated in both the tooth tip and the tooth bottom.

[Other variations]
It should be noted that the embodiment disclosed this time is merely an example in all respects and is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, in the above-described embodiment, the number of teeth is 8 or 9, but the number of teeth may be 7 or less, or 10 or more.

  In the above-described embodiment, the cross-sectional shape of the groove is substantially rectangular, but may be other shapes such as a semicircular shape or a parabolic shape.

1 Inner rotor 2 Hole 3 Tooth 4 Groove 5 Bush 11 Inner rotor 12 Hole 13 Tooth 14 Groove 15 Bush

Claims (2)

A predetermined number of teeth are formed on the outer periphery, and an inner rotor of an internal gear pump having a hole for bush press-fitting in the center,
Along the periphery of the hole, the same number of grooves as the number of teeth are formed at equal intervals corresponding to the positions of the teeth ,
An inner rotor of an internal gear pump, wherein the width and depth of each groove are the same as each other .   2. The inscribed type according to claim 1, wherein the inner rotor is formed of a sintered body obtained by sintering a compact of iron-based metal powder, and the groove is formed corresponding to a tooth tip position of the tooth. Inner rotor of gear pump.

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