JP2005068999A - Oil pump rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of noise, deterioration in pump performance and lowering of mechanical efficiency, by setting a tooth shape of mutually meshing inner rotor and outer rotor in a proper shape. <P>SOLUTION: This oil pump rotor has a tooth surface shape comprising a curve obtained by separating at least either one of the inner rotor 10 or the outer rotor 20 by a distance of 1/4 to 3/4 of tip clearance by dividing a cycloid curve into two parts at the central point. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil pump rotor that sucks and discharges fluid by changing the volume of a cell formed between an inner rotor and an outer rotor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, internal gear type oil pumps having a small size and a simple structure have been widely used as automobile lubricating oil pumps, automatic transmission oil pumps, and the like. Such an oil pump includes an inner rotor formed with n (n is a natural number) external teeth, an outer rotor formed with n + 1 internal teeth that mesh with the external teeth, and a suction port through which fluid is sucked. And a casing formed with a discharge port through which fluid is discharged, and by rotating the inner rotor, the outer teeth mesh with the inner teeth to rotate the outer rotor, and a plurality of cells formed between the two rotors. The fluid is sucked and discharged by the change in volume.
[0003]
In such an internal gear type oil pump, for the purpose of reducing noise and improving mechanical efficiency, a tip clearance of an appropriate size is set between the teeth of both rotors, or a cycloid curve or the like is used. A device such as correcting the tooth profile has been added. Specifically, various measures have been taken, such as correction to flatten the cycloid curve by providing clearance between the tooth surfaces of both rotors by uniformly driving the tooth profile of the outer rotor (see, for example, Patent Documents). 1).
[0004]
[Patent Document 1]
JP 05-256268 A
[0005]
[Problems to be solved by the invention]
However, conventional studies such as setting the tip clearance by driving the tooth profile uniformly, adjusting the diameter of the rolling circle that creates the cycloid curve, and flattening the cycloid curve by configuring a part of the tooth profile as a straight line have been studied. In this measure, the tip clearance is set appropriately, but the clearance of the entire tooth surface is increased, resulting in an increase in torque transmission loss due to rattling between the rotors and slippage between the tooth surfaces, and the impact between the rotors. There was a problem such as noise.
Furthermore, if the clearance between the tooth surfaces becomes inappropriate due to the setting of the tooth surface shape, there is a problem that pressure pulsation of the fluid occurs or increases, resulting in a decrease in pump performance and mechanical efficiency, noise, and the like.
[0006]
The present invention has been made in view of such problems, and the tooth shapes of the inner rotor and the outer rotor that mesh with each other are set to appropriate shapes to prevent reduction in pump performance and mechanical efficiency, and prevention of noise generation. With the goal.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the oil pump rotor of the present invention divides the cycloid curve forming the tooth tip part into two equal parts at the center point and separates them from each other along the circumferential direction of the base circle. This is characterized in that the tooth thickness in the circumferential direction of the portion is increased and the tooth surface interval (clearance) in the tooth width direction in the meshing of both rotors is reduced.
[0008]
That is, in the oil pump rotor according to the first aspect of the present invention, the center point of the abduction cycloid curve created by the abduction circle Ai in which the tooth tip portion of the inner rotor circumscribes the base circle Di and rolls without slipping is provided. The two external tooth partial curves obtained by equally dividing are separated along the circumferential direction of the basic circle Di, and the two external tooth partial curves thus separated are connected by a curve or a straight line and drawn smoothly. It is characterized by being formed as a tooth profile.
[0009]
In this oil pump rotor, the tooth profile of the tooth groove portion of the inner rotor is formed on the basis of an inversion cycloid curve created by an inversion circle Bi that inscribes the base circle Di and rolls without slipping. Further, the outer rotor has an abduction cycloid curve created by an abduction circle Ao that circumscribes the base circle Do and rolls without slipping as a tooth shape of the tooth gap portion, and is inscribed by an inscribed circle Bo that inscribes the base circle Do and rolls without slipping. The created adduction cycloid curve is formed as the tooth profile of the tooth tip.
[0010]
In this oil pump rotor, the size of the tip clearance (the center of both rotors is connected at the rotational position where the tips of the outer teeth of the inner rotor and the tips of the inner teeth of the outer rotor face each other). When the total distance between the tooth surfaces on the line is t) and the distance between the separated external tooth curve is α, both rotors are
t / 4 ≦ α ≦ 3t / 4
It is formed to satisfy.
[0011]
In this oil pump rotor, the distance α between the separated external tooth curve is
2t / 5 ≦ α ≦ 3t / 5
It is more preferable to satisfy.
[0012]
The oil pump rotor according to the invention of claim 3 bisects an inversion cycloid curve created by an inversion circle Bo in which a tooth tip portion of an outer rotor is inscribed in a base circle Do and rolls without slipping at the center point. Then, the two internal tooth partial curves obtained are separated along the circumferential direction of the base circle Do, and the two internal tooth partial curves thus separated are connected by a curve or a straight line so that the curve is drawn smoothly. It is characterized by being formed as a tooth profile.
[0013]
In this oil pump rotor, the tooth profile of the tooth groove portion of the outer rotor is formed based on an inversion cycloid curve created by an abduction circle Ao circumscribing the base circle Do and rolling without slipping.
Further, the inner rotor uses an abduction cycloid curve created by an abduction circle Ai that circumscribes the base circle Di and rolls without slipping as a tooth profile at the tip of the tooth, and an inversion circle Bi that inscribes the base circle Di and rolls without slipping. Is formed as the tooth profile of the tooth gap portion.
[0014]
In this oil pump rotor, when the size of the tip clearance is t and the distance between the separated internal tooth curve is β, both rotors are
t / 4 ≦ β ≦ 3t / 4
It is formed to satisfy.
[0015]
Moreover, in this oil pump rotor, the distance β between the separated internal tooth partial curves is
2t / 5 ≦ β ≦ 3t / 5
It is more preferable to satisfy.
[0016]
The oil pump rotor according to the invention of claim 5 bisects the abduction cycloid curve created by the abduction circle Ai in which the tooth tip portion of the inner rotor circumscribes the base circle Di and rolls without slipping at the center point. The two external tooth partial curves obtained are separated along the circumferential direction of the base circle Di, and the two external tooth partial curves thus separated are connected by a curve or a straight line so that the curve is drawn smoothly. And the tip part of the outer rotor was inscribed in the base circle Do and rolled without slippage, and the inversion cycloid curve created by the inversion circle Bo was divided into two equal parts at the center point. Two internal tooth partial curves are spaced apart along the circumferential direction of the base circle Do, and these separated internal tooth partial curves are connected by a curve or straight line to form a curved line drawn as a tooth profile. It is characterized in that there.
[0017]
In this oil pump rotor, the tooth profile of the tooth groove portion of the inner rotor is formed on the basis of an inversion cycloid curve created by an inversion circle Bi that inscribes the base circle Di and rolls without slipping.
Further, the tooth profile of the tooth groove portion of the outer rotor is formed based on an abduction cycloid curve created by an abduction circle Ao circumscribing the base circle Do and rolling without slipping.
[0018]
And in this oil pump rotor, when the size of the tip clearance is t, the distance between the separated external tooth partial curves is α, and the distance between the internal tooth partial curves is β,
t / 4 ≦ α ≦ 3t / 4, t / 4 ≦ β ≦ 3t / 4
It is formed to satisfy.
[0019]
Further, in this oil pump rotor, the distance α between the separated external tooth partial curves, the distance β between the internal tooth partial curves,
2t / 5 ≦ α ≦ 3t / 5, 2t / 5 ≦ β ≦ 3t / 5
It is more preferable to satisfy.
[0020]
According to the present invention, the tooth profile of at least one of the inner rotor and the outer rotor slightly increases the circumferential tooth thickness of the tooth tip by displacing a partial curve based on the cycloid curve along the circumferential direction. Since it is formed, it is possible to obtain an oil pump rotor in which not only the tip clearance but also the clearance of the entire tooth surface is appropriately set.
[0021]
That is, based on the shape of the oil pump rotor in which the tip clearance is appropriately formed, the tip surface of the tooth tip does not change by forming the tooth surface of the tooth tip portion in the circumferential direction of the base circle. Since the circumferential tooth thickness is large, it is possible to obtain an oil pump rotor that is more silent and mechanical performance than conventional.
[0022]
The number of outer teeth of the inner rotor is n (n is a natural number), the number of teeth of the inner teeth of the outer rotor is (n + 1), the diameter of the basic circle Di of the inner rotor is φDi, and the diameter of the abduction circle Ai ΦAi, the diameter of the inversion circle Bi is φBi, the diameter of the outer circle basic circle Do is φDo, the diameter of the abduction circle Ao is φAo, the diameter of the inversion circle Bo is φBo, and the amount of eccentricity between the inner rotor and the outer rotor As e
φAi + t / (n + 2) = φAo, φBi = φBo
φAi + φBi = 2e
φDi = n · (φAi + φBi)
φDo = φDi · (n + 1) / n + t · (n + 1) / (n + 2)
If the inner rotor and the outer rotor are formed so as to satisfy, the clearance between the tooth surfaces of both rotors becomes appropriate.
[0023]
Also,
φAi = φAo, φBi + t / (n + 2) = φBo
φAi + φBi = 2e
φDi = n · (φAi + φBi)
φDo = φDi · (n + 1) / n + t · (n + 1) / (n + 2)
Even if the inner rotor and the outer rotor are formed so as to satisfy the above, the clearance between the tooth surfaces can be appropriately formed.
[0024]
Also,
φAi + t / 2 = φAo, φBi−t / 2 = φBo
φAi + φBi = φAo + φBo = 2e
φDi = n · (φAi + φBi), φDo = (n + 1) · (φAo + φBo)
(N + 1) · φDi = n · φDo
Even if the inner rotor and the outer rotor are formed so as to satisfy the above, the clearance between the tooth surfaces can be appropriately formed.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The oil pump shown in FIG. 1 has (n + 1) sheets (this embodiment) meshing with the outer rotor 11 and the inner rotor 10 formed with n pieces (n is a natural number, n = 10 in this embodiment) of outer teeth 11. The outer rotor 20 is formed with 11 inner teeth 21 in the form, and the inner rotor 10 and the outer rotor 20 are housed inside the casing 30.
[0026]
A plurality of cells C are formed between the tooth surfaces of the inner rotor 10 and the outer rotor 20 along the rotational direction of the rotors 10 and 20. Each cell C is individually partitioned by the contact between the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 on the front and rear sides in the rotational direction of the rotors 10 and 20, respectively. It is partitioned by the casing 30, thereby forming an independent fluid transfer chamber. The cell C rotates with the rotation of the rotors 10 and 20, and repeats the increase and decrease in volume with one rotation as one cycle.
[0027]
The casing 30 is provided with a suction port that communicates with the cell C when the volume increases, and a discharge port that communicates with the cell C when the volume decreases. It is conveyed with the rotation of 10, 20 and discharged from the discharge port.
[0028]
Here, the clearance between the tip of the tooth tip portion 12 of the inner rotor 10 and the tip of the tooth tip portion 22 of the outer rotor 20 facing each other on a straight line connecting the centers Oi and Oo of each rotor is referred to as a tip clearance. The size t of the tip clearance is set so that the clearance between the tooth tip portion 12 of the inner rotor 10 and the tooth groove portion 23 of the outer rotor 20 meshing with each other on the opposite side of the straight line passing through the centers Oi and Oo is zero. , 20 is the size when arranged.
When the rotor is driven, the center Oi of the inner rotor 10 and the center Oo of the outer rotor 20 have equal t / 2 clearances between the tooth surfaces facing each other at two points on a straight line passing through the centers Oi and Oo. So as to be eccentric. The amount of eccentricity of the centers Oi and Oo is assumed to be e.
[0029]
The inner rotor 10 is attached to a rotating shaft and supported so as to be rotatable about a center Oi. The outer rotor circle Ai (diameter φAi) circumscribes the basic circle Di (diameter φDi) of the inner rotor 10 and rolls without slipping. The tooth profile of the external teeth 11 is formed on the basis of the abduction cycloid curve 16 created by the above and the abduction cycloid curve 17 created by the inversion circle Bi (diameter φBi) inscribed in the base circle Di and rolling without slipping. Has been.
[0030]
The outer rotor 20 is arranged with the center Oo eccentrically (eccentric amount: e) with respect to the center Oi of the inner rotor 10, and is supported in the casing 30 so as to be rotatable about the center Oo. The inner teeth 21 of the outer rotor 20 are inscribed in the abduction cycloid curve 27 created by an abduction circle Ao (diameter φAo) that circumscribes the base circle Do (diameter φDo) and slides inscribed in the base circle Do. The tooth profile is formed on the basis of the adductor cycloid curve 26 created by the inwardly rotating circle Bo (diameter φBo) that rolls.
[0031]
Here, the following relational expression is established between the inner rotor 10 and the outer rotor 20. Here, the unit of dimension is mm (millimeter).
[0032]
Regarding the curve that forms the tooth shape of the inner rotor 10, an integral multiple (number of teeth times) of the sum of the rolling distances of the outer rotation circle Ai and the inner rotation circle Bi must be equal to the circumference of the basic circle Di. From
π · φDi = n · π · (φAi + φBi)
That is, φDi = n · (φAi + φBi) (Ia)
[0033]
Similarly, with respect to the curve that forms the tooth shape of the outer rotor 20, the integral multiple (the number of teeth) of the sum of the rolling distances of the outer rotation circle Ao and the inner rotation circle Bo must be equal to the circumference of the basic circle Do. Because you have to
π · φDo = (n + 1) · π · (φAo + φBo)
That is, φDo = (n + 1) · (φAo + φBo) (Ib)
[0034]
Next, since the inner rotor 10 and the outer rotor 20 mesh with each other,
φAi + φBi = φAo + φBo = 2e (II)
From the above formulas (Ia), (Ib), (II),
(N + 1) · φDi = n · φDo (III)
[0035]
Further, when the tooth tip of the outer tooth 11 and the tooth tip of the inner tooth 21 face each other at a position advanced by a half turn from the meshing position of the rotors 10 and 20, the size of the clearance t / From 2
φAi + t / 2 = φAo
φBi−t / 2 = φBo
Satisfy the relationship.
[0036]
Here, the detailed shape of the outer teeth 11 of the inner rotor 10 will be described with reference to FIGS. 2 (a) to 2 (c). The outer teeth 11 of the inner rotor 10 are formed with tooth tips 12 and tooth gaps 13 alternately and continuously in the circumferential direction.
[0037]
In order to draw the shape of the tooth tip portion 12, first, the abduction cycloid curve 16 (FIG. 2 (a)) by the abduction circle Ai is divided into two equal parts at the center point A, and the external tooth partial curves 12a, 12b and To do. Here, the center point A of the abduction cycloid curve 16 is a point that symmetrically bisects the abduction cycloid curve 16 created by rotating the abduction circle Ai on the basic circle Di of the inner rotor 10 without slipping. In other words, when the abduction circle Ai rotates halfway, one point on the abduction circle Ai that draws the abduction cycloid curve 16 arrives.
Next, as shown in FIG. 2B, the external tooth partial curves 12a and 12b are displaced around the center Oi of the basic circle Di along the circumferential direction of the basic circle Di, and a distance α between the two curves 12a and 12b is obtained. Only separate. At this time, an angle formed by two line segments connecting the ends of both curves 12a and 12b and the center Oi of the basic circle Di is defined as θi.
Then, as shown in FIG. 2 (c), the two curved lines 12 a and 12 b separated from each other are connected by a complementary line 14 formed of a curve or a straight line, and the obtained continuous line is used as the tooth surface shape of the tooth tip portion 12. .
That is, the tooth tip portion 12 is formed by a continuous line composed of the external tooth portion curve 12a and the external tooth portion curve 12b that are separated from each other, and the complementary line 14 that connects the two curves 12a and 12b.
[0038]
As a result, the tooth tip 12 of the inner rotor 10 has two line segments connecting both ends of the complementary line 14 and the center Oi of the basic circle Di, as compared with a tooth tip shape consisting only of a simple abduction cycloid curve 16. The tooth thickness is increased in the circumferential direction by the angle θi formed by In addition, in this embodiment, although the complement line 14 which connects between the both external tooth part curves 12a and 12b is made into the straight line, the complement line 14 may be a curve.
[0039]
In this embodiment, the tooth tip portion 12 having the increased tooth thickness in the circumferential direction is formed by reducing the width in the circumferential direction of the tooth gap portion 13 in this embodiment, and the tooth surface shape is smoothly continued over the entire circumference. ing.
That is, in order to draw the shape of the tooth gap portion 13, first, the adduction cycloid curve 17 (FIG. 2 (a)) by the addendum circle Bi is divided into two equal parts at the center point B to form partial curves 13a and 13b. . Here, the center point B of the inversion cycloid curve 17 is a point that symmetrically bisects the inversion cycloid curve 17 created by rotating the inversion circle Bi one time on the basic circle Di of the inner rotor 10 without slipping. In other words, when the inversion circle Bi rotates halfway, one point on the inversion circle Bi that draws the inversion cycloid curve 17 arrives. Next, as shown in FIG. 2B, the partial curves 13a and 13b are arranged in the circumferential direction of the basic circle Di so as to connect the end points of both curves 13a and 13b to the end points of the continuous line that draws the tooth tip portion 12. Displace along. At this time, both the curves 13a and 13b intersect with the center point B as the center, and the angle formed by the two line segments connecting both ends of the intersection 15 and the center Oi of the basic circle Di is θi. Then, as shown in FIG. 2C, a continuous line in which both the curves 13 a and 13 b are smoothly connected is defined as a tooth surface shape of the tooth gap portion 13.
As a result, the tooth gap portion 13 has a shape having a smaller width in the circumferential direction by the angle θi as compared with a tooth groove shape consisting of only the simple inversion cycloid curve 17.
[0040]
In other words, the outer teeth 11 of the inner rotor 10 are tooth teeth as compared with the case where the abduction cycloid curve 16 and the adduction cycloid curve 17 created by the abduction circle Ai and the inversion circle Bi are directly shaped as tooth surfaces. The circumferential tooth thickness of the tip portion 12 is increased and the circumferential width of the tooth gap portion 13 is reduced.
[0041]
Here, in the inner rotor 10, the distance α between the two external tooth curve segments 12a and 12b is:
t / 4 ≦ α
Is set to satisfy the range of, more preferably
2t / 5 ≦ α
By satisfying this range, the clearance between the tooth surfaces with respect to the outer rotor 20 becomes appropriate, and the quietness is sufficiently improved.
[0042]
In the inner rotor 10, the distance α between the two external tooth curve segments 12a and 12b is
α ≦ 3t / 4
Is set to satisfy the range of, more preferably
α ≦ 3t / 5
By satisfying this range, it is possible to prevent the clearance with respect to the outer rotor 20 from becoming too small, and to prevent the oil pump rotor from rotating, increasing the amount of wear, and reducing the durability.
[0043]
Next, the shape of the inner teeth 21 of the outer rotor 20 will be described with reference to FIGS. 3 (a) to 3 (c). The internal teeth 21 are formed by alternately and continuously forming a tooth tip portion 22 and a tooth groove portion 23 in the circumferential direction.
[0044]
In order to draw the shape of the tooth tip portion 22, first, the adduction cycloid curve 26 (FIG. 3 (a)) by the addendum circle Bo is divided into two equal parts at the center point C, and the inner tooth partial curves 22a, 22b and To do. Here, the center point C of the inversion cycloid curve 26 is a point that symmetrically bisects the inversion cycloid curve 26 that is created by rotating the inversion circle Bo on the basic circle Do of the outer rotor 20 without slipping. In other words, when the inversion circle Bo is rotated halfway, one point on the inversion circle Bo that draws the inversion cycloid curve 26 arrives. Next, as shown in FIG. 3B, the internal tooth partial curves 22a and 22b are displaced along the circumferential direction of the basic circle Do so as to be separated from each other, thereby separating the two curves 22a and 22b by a distance β. At this time, an angle formed by two line segments connecting the end portions of both curves 22a and 22b and the basic circle Do is defined as θo. Then, as shown in FIG. 3C, the spaced apart internal tooth portion curves 22 a and 22 b are connected by a complementary line 24 made of a straight line, and the obtained continuous line is defined as the shape of the tooth tip portion 22.
That is, the tooth tip portion 22 is formed by a continuous line composed of the inner tooth portion curve 22a and the inner tooth portion curve 22b that are separated from each other, and the complementary line 24 that connects the two curves 22a and 22b.
[0045]
As a result, the tooth tip portion 22 has an angle θo formed by two line segments connecting both ends of the complementary line 24 and the center Oo of the base circle Do as compared with a tooth tip shape consisting of only a simple adduction cycloid curve 26. Thus, the tooth thickness is increased in the circumferential direction. In the present embodiment, the complementary line 24 connecting the two internal tooth partial curves 22a and 22b is a straight line, but the complementary line 24 may be a curved line.
[0046]
In this embodiment, the tooth tip portion 22 having an increased tooth thickness in the circumferential direction is formed by reducing the circumferential width of the tooth gap portion 23 in this embodiment, and the tooth surface shape is smoothly continued over the entire circumference. ing.
That is, in order to draw the shape of the tooth gap 23, first, the abduction cycloid curve 27 (FIG. 3 (a)) by the abduction circle Ao is divided into two equal parts at the center point D to form partial curves 23a and 23b. . Here, the center point D of the abduction cycloid curve 27 is a point that symmetrically bisects the abduction cycloid curve 27 created by rotating the abduction circle Ao on the basic circle Do of the outer rotor 20 without slipping. In other words, when the abduction circle Ao rotates halfway, one point on the abduction circle Ao that draws the abduction cycloid curve 27 arrives.
Next, as shown in FIG. 3 (b), the partial curves 23a and 23b are arranged in the circumferential direction of the basic circle Do so as to connect the end points of both curves 23a and 23b to the end points of the continuous line that draws the tooth tip portion 22. Displace along. At this time, both the curves 23a and 23b intersect with the center point D as the center, and an angle formed by two line segments connecting both ends of the intersecting portion 25 and the center Oo of the basic circle Do is θo.
And as shown in FIG.3 (c), let the continuous line which connected both the curves 23a and 23b smoothly be the tooth surface shape of the tooth gap part 23. FIG.
As a result, the tooth gap 23 has a shape having a smaller width in the circumferential direction by the angle θo as compared with a tooth groove formed by only a simple abduction cycloid curve 27.
[0047]
In other words, the inner teeth 21 of the outer rotor 20 have tooth shapes compared to the case where the abduction cycloid curve 27 and the adduction cycloid curve 26 created by the abduction circle Ao and the inversion circle Bo are directly used as tooth surfaces. The circumferential tooth thickness of the tip portion 22 is increased, and the circumferential width of the tooth gap portion 23 is reduced.
[0048]
Here, in the outer rotor 20, the distance β between the two internal tooth partial curves 22 a and 22 b is
t / 4 ≦ β
Is set to satisfy the range of, more preferably
2t / 5 ≦ β
By satisfying this range, the clearance between the tooth surfaces with respect to the inner rotor 10 becomes appropriate, and the quietness is sufficiently improved.
[0049]
Further, in the outer rotor 20, the distance β between the two inner tooth partial curves 22a and 22b is
β ≦ 3t / 4
Is set to satisfy the range of, more preferably
β ≦ 3t / 5
By satisfying this range, it is possible to prevent the clearance with respect to the inner rotor 10 from becoming too small, and to prevent the inability to rotate, the increase in wear amount, and the decrease in durability.
[0050]
1 shows φDi = 52 mm, φAi = 2.5 mm, φBi = 2.7 mm, φDo = 57.2 mm, φAo = 2.56 mm, φBo = 2.64 mm, e = 2.6 mm, and t = 0. 12 mm, the distance α between both external tooth partial curves 12a and 12b and the distance β between both internal tooth partial curves 22a and 22b,
α = β = t / 2 (= 0.06 mm)
The inner rotor 10 and the outer rotor 20 formed as shown in FIG.
[0051]
In the inner rotor 10 and the outer rotor 20, α and β are extremely small, and it is difficult to understand the displacement of each partial curve at the actual size. Therefore, FIGS. 2 (a) to 2 (c) and FIGS. 3 (a) to 3 ( In c), in order to explain the detailed shape of the tooth surface, each displacement amount is greatly exaggerated and is different from the actual shape shown in FIG.
[0052]
In the above embodiment, the shape of the tooth tip portions 12 and 22 is increased in the circumferential direction for both the inner rotor 10 and the outer rotor 20, but the present invention is not limited to this, and the inner rotor 10 and As the shape in which any one tooth tip portion of the outer rotor 20 is increased, the cycloid curve itself may be formed as a tooth surface shape without applying the above-described correction.
[0053]
In addition, a curve that satisfies the following relational expression between the inner rotor 10 and the outer rotor 20 can also be adopted as a curve that serves as a basis for applying the above-described correction.
[0054]
That is, for the curve that forms the tooth shape of the inner rotor 10, an integral multiple (number of teeth times) of the sum of the rolling distances of the outer rotation circle Ai and the inner rotation circle Bi must be equal to the circumference of the basic circle Di. Because it does not become
π · φDi = n · π · (φAi + φBi)
That is, φDi = n · (φAi + φBi) (Ia)
[0055]
Similarly, with respect to the curve that forms the tooth shape of the outer rotor 20, the integral multiple (the number of teeth) of the sum of the rolling distances of the outer rotation circle Ao and the inner rotation circle Bo must be equal to the circumference of the basic circle Do. Because you have to
π · φDo = (n + 1) · π · (φAo + φBo)
That is, φDo = (n + 1) · (φAo + φBo) (Ib)
[0056]
Next, in order to properly form the clearance between the central part of the tooth groove of the inner rotor 10 and the central part of the tooth tip of the outer rotor 20, the relationship between the inversion circles Bi and Bo is determined.
φBi = φBo
On the other hand, the basic circle Do of the outer rotor 20 is
φDo = φDi · (n + 1) / n + t · (n + 1) / (n + 2)
Shall be satisfied.
[0057]
Accordingly, since the integral multiple (the number of teeth) of the sum of the rolling distances of the abduction circle Ao and the inversion circle Bo must be equal to the circumference of the basic circle Do, the abduction circle Ao is
φAo = φAi + t / (n + 2)
And
The oil pump rotor of the present invention can be formed based on a curve that satisfies the above relationship.
[0058]
It can also be based on a curve that satisfies the following relationship.
That is, for the curve that forms the tooth shape of the inner rotor 10, an integral multiple (number of teeth times) of the sum of the rolling distances of the outer rotation circle Ai and the inner rotation circle Bi must be equal to the circumference of the basic circle Di. Because it does not become
π · φDi = n · π · (φAi + φBi)
That is, φDi = n · (φAi + φBi) (Ia)
[0059]
Similarly, with respect to the curve that forms the tooth shape of the outer rotor 20, the integral multiple (the number of teeth) of the sum of the rolling distances of the outer rotation circle Ao and the inner rotation circle Bo must be equal to the circumference of the basic circle Do. Because you have to
π · φDo = (n + 1) · π · (φAo + φBo)
That is, φDo = (n + 1) · (φAo + φBo) (Ib)
[0060]
Next, in order to properly form the clearance between the center of the tooth tip of the inner rotor 10 and the center of the tooth gap of the outer rotor 20, the relationship between the abduction circles Ai and Ao is determined.
φAi = φAo
On the other hand, the basic circle Do of the outer rotor 20 is
φDo = φDi · (n + 1) / n + t · (n + 1) / (n + 2)
Shall be satisfied.
[0061]
Accordingly, since the integral multiple (the number of teeth) of the sum of the rolling distances of the abduction circle Ao and the adduction circle Bo must be equal to the circumference of the basic circle Do,
φBo = φBi + t / (n + 2)
The oil pump rotor of the present invention can be formed based on a curve that satisfies the above relationship.
[0062]
【The invention's effect】
As described above, according to the oil pump rotor of the present invention, the tooth profile of at least one of the inner rotor and the outer rotor forms a tooth surface based on the shape of the oil pump rotor in which the tip clearance is appropriately formed. The cycloid curve is divided into two equal parts at the center point, and the obtained two partial curves are displaced along the circumferential direction of the base circle, so that the tip position of the tooth tip portion does not change. In addition, since the tooth thickness in the circumferential direction is large, it is possible to obtain an oil pump rotor that is more excellent in quietness and mechanical performance than in the past.
[0063]
In particular, the clearance between the tooth surfaces of both rotors can be reduced by setting the distance α between the external tooth partial curves and the distance β between the internal tooth partial curves to be ¼ or more of the tip clearance. An oil pump having high mechanical efficiency and high quietness can be provided by preventing rattling and pulsation between rotors caused by a large clearance between the surfaces.
[0064]
Further, by setting the distance α between the outer tooth partial curves and the distance β between the inner tooth partial curves to be 3/4 or less of the tip clearance, the clearance between the tooth surfaces of both rotors can be secured. It is possible to realize an oil pump rotor that rotates at high speed and has high durability.
[Brief description of the drawings]
FIG. 1 is a diagram showing an oil pump rotor according to an embodiment of the present invention.
FIG. 2 is a partially enlarged view showing a tooth shape of an inner rotor constituting the oil pump rotor shown in FIG. 1;
3 is a partially enlarged view showing a tooth shape of an outer rotor constituting the oil pump rotor shown in FIG. 1. FIG.
[Explanation of symbols]
10 Inner rotor
11 external teeth
12 Tooth tips
12a external tooth curve
12b External tooth curve
13 tooth gap
13a Partial curve
13b Partial curve
14 Complementary line
15 Intersection
20 Outer rotor
21 internal teeth
22 tooth tip
22a Internal tooth curve
22b Internal tooth curve
23 tooth gap
23a Partial curve
23b Partial curve
24 Complementary line
25 Intersection

Claims (9)

An inner rotor formed with n (n is a natural number) external teeth, an outer rotor formed with (n + 1) internal teeth engaging with the external teeth, a suction port for sucking fluid, and a fluid are discharged And an oil pump that conveys fluid by sucking and discharging fluid by a volume change of a cell formed between the tooth surfaces of both rotors when the rotors mesh with each other and rotate. In the oil pump rotor used,
An outer rotation cycloid curve created by an abduction circle Ao that circumscribes the base circle Do and rolls without slippage is formed as a tooth shape of the tooth gap, and is created by an inversion circle Bo that inscribes the base circle Do and rolls without slipping. Is formed as the tooth profile of the tip of the addendum cycloid curve,
The tooth profile of the tooth groove portion of the inner rotor is formed on the basis of an inversion cycloid curve created by an inversion circle Bi inscribed in the base circle Di and rolling without slipping,
An outer rotation cycloid curve created by an abduction circle Ai in which the tooth tip portion of the inner rotor circumscribes the base circle Di and rolls without slipping is divided into two equal parts at the center point, and two outer tooth partial curves obtained are obtained. Is formed along the circumferential direction of the base circle Di, and the curved line drawn by smoothly connecting these two external tooth partial curves separated by a curve or a straight line is formed as a tooth profile,
When the size of the tip clearance is t and the distance between the separated external tooth curve is α,
t / 4 ≦ α ≦ 3t / 4
An oil pump rotor characterized by satisfying The distance α between the separated external tooth partial curves is 2t / 5 ≦ α ≦ 3t / 5.
The oil pump rotor according to claim 1, wherein: An inner rotor having n (n is a natural number) external teeth, an outer rotor having (n + 1) internal teeth meshing with the external teeth, a suction port for sucking fluid, and a fluid discharge And a casing having a discharge port formed therein, and an oil pump that conveys fluid by sucking and discharging fluid by a change in the volume of cells formed between the tooth surfaces of both rotors when both rotors mesh and rotate In the oil pump rotor used for
The inner rotor is formed by an abduction cycloid curve created by an abduction circle Ai that circumscribes the base circle Di and rolls without slipping, and has an addendum circle Bi that inscribes the base circle Di and rolls without slipping. The created adductor cycloid curve is formed as the tooth profile of the tooth gap part,
The tooth profile of the tooth groove portion of the outer rotor is formed based on an abduction cycloid curve created by an abduction circle Ao circumscribing the base circle Do and rolling without slipping,
An inner rotation cycloid curve created by an inversion circle Bo in which the tooth tip portion of the outer rotor is inscribed in the basic circle Do and rolls without slipping is divided into two at the center point, and two inner tooth partial curves obtained are obtained. Is formed along the circumferential direction of the basic circle Do, and a curved line drawn by smoothly connecting these two internal tooth partial curves separated by a curved line or a straight line is formed as a tooth profile,
When the size of the tip clearance is t and the distance between the separated internal tooth curve is β,
t / 4 ≦ β ≦ 3t / 4
An oil pump rotor characterized by satisfying The distance β between the separated internal tooth partial curves is
2t / 5 ≦ β ≦ 3t / 5
The oil pump rotor according to claim 3, wherein: An inner rotor having n (n is a natural number) external teeth, an outer rotor having (n + 1) internal teeth meshing with the external teeth, a suction port for sucking fluid, and a fluid discharge And a casing having a discharge port formed therein, and an oil pump that conveys fluid by sucking and discharging fluid by a change in the volume of cells formed between the tooth surfaces of both rotors when both rotors mesh and rotate In the oil pump rotor used for
The tooth profile of the tooth groove portion of the inner rotor is formed on the basis of an inversion cycloid curve created by an inversion circle Bi inscribed in the base circle Di and rolling without slipping,
An outer rotation cycloid curve created by an abduction circle Ai in which the tooth tip portion of the inner rotor circumscribes the base circle Di and rolls without slipping is divided into two equal parts at the center point, and two outer tooth partial curves obtained are obtained. Is formed along the circumferential direction of the base circle Di, and the curved line drawn by smoothly connecting these two external tooth partial curves separated by a curve or a straight line is formed as a tooth profile,
The tooth profile of the tooth groove portion of the outer rotor is formed based on an abduction cycloid curve created by an abduction circle Ao circumscribing the base circle Do and rolling without slipping,
An inner rotation cycloid curve created by an inversion circle Bo in which the tooth tip portion of the outer rotor is inscribed in the basic circle Do and rolls without slipping is divided into two at the center point, and two inner tooth partial curves obtained are obtained. Is formed along the circumferential direction of the basic circle Do, and a curved line drawn by smoothly connecting these two internal tooth partial curves separated by a curved line or a straight line is formed as a tooth profile,
When the tip clearance size t, the distance between the separated external tooth partial curves is α, and the distance between the internal tooth partial curves is β,
t / 4 ≦ α ≦ 3t / 4, t / 4 ≦ β ≦ 3t / 4
An oil pump rotor characterized by satisfying The distance α between the external tooth partial curves separated from each other, and the distance β between the internal tooth partial curves,
2t / 5 ≦ α ≦ 3t / 5, 2t / 5 ≦ β ≦ 3t / 5
The oil pump rotor according to claim 5, wherein: The diameter of the base circle Di of the inner rotor is φDi, the diameter of the abduction circle Ai is φAi, the diameter of the inversion circle Bi is φBi, the diameter of the foundation circle Do of the outer rotor is φDo, and the diameter of the abduction circle Ao is φAo The diameter of the inversion circle Bo is φBo, and the eccentricity between the inner rotor and the outer rotor is e.
φAi + t / (n + 2) = φAo, φBi = φBo
φAi + φBi = 2e
φDi = n · (φAi + φBi)
φDo = φDi · (n + 1) / n + t · (n + 1) / (n + 2)
The oil pump rotor according to claim 1, wherein: The diameter of the base circle Di of the inner rotor is φDi, the diameter of the abduction circle Ai is φAi, the diameter of the inversion circle Bi is φBi, the diameter of the foundation circle Do of the outer rotor is φDo, and the diameter of the abduction circle Ao is φAo The diameter of the inversion circle Bo is φBo, and the eccentricity between the inner rotor and the outer rotor is e.
φAi = φAo, φBi + t / (n + 2) = φBo
φAi + φBi = 2e
φDi = n · (φAi + φBi)
φDo = φDi · (n + 1) / n + t · (n + 1) / (n + 2)
The oil pump rotor according to claim 1, wherein: The diameter of the base circle Di of the inner rotor is φDi, the diameter of the abduction circle Ai is φAi, the diameter of the inversion circle Bi is φBi, the diameter of the foundation circle Do of the outer rotor is φDo, and the diameter of the abduction circle Ao is φAo The diameter of the inversion circle Bo is φBo, and the eccentricity between the inner rotor and the outer rotor is e.
φAi + t / 2 = φAo, φBi−t / 2 = φBo
φAi + φBi = φAo + φBo = 2e
φDi = n · (φAi + φBi), φDo = (n + 1) · (φAo + φBo)
(N + 1) · φDi = n · φDo
The oil pump rotor according to claim 1, wherein:

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