JP2005069002A - 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 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 or the outer rotor 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, an internal gear type oil pump having a small size and a simple structure has been widely used as a lubricating oil pump for an automobile, an oil pump for an automatic transmission, or 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 tooth tips 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 providing clearance between the tooth surfaces of both rotors by uniformly driving the tooth profile of the outer rotor, and correcting the flattening of the cycloid curve.
[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-mentioned problems, the oil pump rotor of the present invention has a tangential direction in which the cycloid curve forming the tooth tip portion is equally divided by the center point and drawn at the circumferential direction of the basic circle and the center point of the cycloid curve. , The tooth width of the tooth tip portion is widened, and the tooth surface interval (clearance) in the tooth width direction in the meshing state 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. Equally divide the two external tooth partial curves obtained along the tangential direction drawn at the center point of the abduction cycloid curve, and then displace them along the circumferential direction of the base circle Di. In addition, it is characterized in that a curved line drawn by smoothly connecting these two external tooth partial curves with a curved line or a straight line is 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. The two inner tooth partial curves obtained were displaced along the tangential direction drawn at the center point of the adductor cycloid curve, and then displaced along the circumferential direction of the base circle Di, and separated. It is characterized in that it is formed by a curve drawn by connecting two internal tooth partial curves with a curve or straight line and smoothly continuing them.
[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 were displaced along the tangential direction drawn at the center point of the abduction cycloid curve, and then displaced along the circumferential direction of the base circle Di, and separated. An inversion circle in which a curve drawn by connecting two external tooth partial curves with a curve or straight line and smoothly continuing is formed as a tooth shape, and the tooth tip of the outer rotor is inscribed in the base circle Do and rolls without slipping. The addendum cycloid curve created by Bo is divided into two equal parts at its center point, and the two internal tooth partial curves obtained are displaced along the tangential direction drawn at the center point of the addendum cycloid curve and then the foundation Is displaced along the circumferential direction of Di is spaced, is characterized in that it is formed a curve drawn by causing continuous smoothly connect with spaced curved or straight these internal tooth curve segments were as teeth.
[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]
In this oil pump rotor, when the tip clearance is t, the distance between the separated external tooth curve is α, and the distance between the internal tooth curve is β, both rotors are:
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 external tooth partial curves and the distance β between the internal tooth partial curves are
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 is displaced along the circumferential direction of the foundation circle after the tooth surface is displaced along the tangential direction of the center point of the cycloid curve. Thus, since the tooth thickness in the circumferential direction of the tooth tip is slightly increased, an oil pump rotor in which not only the tip clearance but also the entire tooth surface clearance is appropriately set can be obtained.
[0021]
That is, based on the shape of the oil pump rotor with the tip clearance appropriately formed, the tooth tip portion is formed large along the tangential direction drawn at the center point of the cycloid curve and the circumferential direction of the base circle. Since the circumferential tooth thickness is increased without changing the tip position, it is possible to obtain an oil pump rotor that is more silent and mechanical performance than conventional.
[0022]
The number of external teeth of the inner rotor is n, (n is a natural number), the number of internal teeth of the outer rotor is (n + 1), the diameter of the basic circle Di of the inner rotor is φDi, and the abduction circle Ai The diameter is φAi, the diameter of the addendum 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 addendum circle Bo is φBo, and the inner rotor and the outer rotor are eccentric. Let e be the amount
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, from the size of the tip clearance formed between the tooth tips when the tooth tips of the external teeth 11 and the tooth tips of the internal teeth 21 face each other at a position advanced half a turn from the meshing position of the rotors 10 and 20. ,
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 (d). 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, a 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 along the tangential direction drawn at the center point A of the abduction cycloid curve 16, and the distance between the two curves 12a and 12b is obtained. Separate by α ′.
[0038]
Further, as shown in FIG. 2 (c), the external tooth partial curves 12a and 12b are arranged around the center Oi of the basic circle Di so that the two curves 12a and 12b are separated by a distance α. The angle θi / 2 is displaced along the direction.
Then, as shown in FIG. 2 (d), the two separated curves 12 a and 12 b are connected by a complementary line 14 made of 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.
[0039]
As a result, the tooth tip 12 of the inner rotor 10 has a shape in which the tooth thickness is larger in the circumferential direction by the amount of the inserted complementary line 14 compared to the tooth tip shape consisting of only the simple abduction cycloid curve 16. Yes. In the present embodiment, the complementary line 14 that connects between the external tooth partial curves 12a and 12b is a straight line, but the complementary line 14 may be a curved line.
[0040]
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 is half-rotated, one point on the inversion circle Bi that draws the inversion cycloid curve 17 arrives.
Next, as shown in FIG. 2 (b), the partial curves 13a and 13b are turned inward so that the end points of both curved lines 13a and 13b are connected to the end points of both external tooth partial curves 12a and 12b in the displaced state. It is displaced along the tangential direction drawn at the center point B of the cycloid curve 17. Thereby, both the curves 13a and 13b intersect centering on the central point B.
[0041]
Further, as shown in FIG. 2 (c), the partial curves 13a and 13b are arranged along the circumferential direction of the basic circle Di so that the end points of both the curves 13a and 13b are connected to the end points of the continuous line drawing the tooth tip portion 12. To displace.
Then, as shown in FIG. 2 (d), a continuous line in which both 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 with a smaller width in the circumferential direction by the amount of the complementary line 14 inserted into the tooth tip portion 12 as compared with a tooth groove shape consisting of only a simple adduction cycloid curve 17. .
[0042]
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.
[0043]
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.
[0044]
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.
[0045]
Next, the detailed shape of the inner teeth 21 of the outer rotor 20 will be described with reference to FIGS. 3 (a) to 3 (d). The internal teeth 21 are formed by alternately and continuously adding the tooth tip portions 22 and the tooth gap portions 23 in the circumferential direction of the basic circle.
[0046]
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 B of the adduction cycloid curve 26 is a point that symmetrically bisects the adduction cycloid curve 26 created by rotating the addendum circle Bo on the basic circle Do of the outer rotor 20 without slipping. In other words, when the inversion circle Bo is half-rotated, 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 tangential direction drawn at the center point C of the adductor cycloid curve 26, and the distance β between the two curves 22a and 22b is obtained. 'Just apart.
[0047]
Further, as shown in FIG. 3 (c), the inner tooth partial curves 22a and 22b are arranged around the center Oo of the basic circle Do in the circumferential direction so that the two curves 22a and 22b are separated by a distance β. Along each, an angle θo / 2 is displaced.
And as shown in FIG.3 (d), between the spaced apart internal tooth part curve 22a, 22b is connected by the complementary line 24 which consists of a straight line, and the obtained continuous line is made into the shape of the tooth tip part 22. FIG.
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.
[0048]
As a result, the tooth tip portion 22 has a tooth thickness that is thicker in the circumferential direction by the amount of the inserted complementary line 24 than the tooth tip shape consisting of only the simple adduction cycloid curve 26. 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.
[0049]
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 connected to the center point of the abduction cycloid curve 27 so that the end points of both curves 23a and 23b are connected to the end points of both internal tooth partial curves 22a and 22b. It is displaced along the tangential direction drawn by D and intersects with the center point D as the center.
[0050]
Further, as shown in FIG. 3 (c), the partial curves 23 a and 23 b are displaced along the circumferential direction of the basic circle Do, and the end points of both the curves 23 a and 23 b are connected to the end points of the continuous line that draws the tooth tip portion 22. Let
And as shown in FIG.3 (d), the continuous line which connected these partial curves 23a and 23b smoothly is formed, and it is set as the tooth surface shape of the tooth gap part 23. FIG.
As a result, the tooth gap portion 23 has a shape with a smaller width in the basic circumferential direction by the amount of the complementary line 24 inserted into the tooth tip portion 22 as compared with a tooth groove shape consisting only of a simple abduction cycloid curve 27. ing.
[0051]
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.
[0052]
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.
[0053]
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.
[0054]
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.
[0055]
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 (d) and FIGS. 3 (a) to 3 ( In d), the displacement amounts are greatly exaggerated in order to explain the detailed shape of the tooth surface, which is different from the actual shape shown in FIG.
[0056]
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.
[0057]
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.
[0058]
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 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.
[0061]
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.
[0062]
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)
[0063]
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)
[0064]
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.
[0065]
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.
[0066]
【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 two obtained partial curves are displaced along the tangential direction drawn at the center point of the cycloid curve and the circumferential direction of the base circle. As a result, since the circumferential tooth thickness is increased without changing the tip position of the tooth tip portion, an oil pump rotor that is more excellent in quietness and mechanical performance than before can be obtained.
[0067]
In particular, by setting the distance α between the outer tooth partial curves and the distance β between the inner tooth partial curves to be ¼ or more of the tip clearance, and more preferably 2/5 or more, the clearance between the tooth surfaces of both rotors is reduced. Since the rotor can be made small, rattling and pulsation between the rotors caused by the large clearance between the tooth surfaces can be prevented, and an oil pump with high mechanical efficiency and high quietness can be provided.
[0068]
Further, by setting the distance α between the external tooth partial curves and the distance β between the internal tooth partial curves to 3/4 or less of the tip clearance, more preferably 3/5 or less, the clearance between the tooth surfaces of both rotors is achieved. Therefore, an oil pump rotor that rotates smoothly and has good durability can be realized.
[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
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

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 slipping is formed as a tooth shape of the tooth gap part, and the outer rotor 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 displaced along the tangential direction drawn at the center point of the abduction cycloid curve, and then displaced along the circumferential direction of the base circle Di and separated, and the two external tooth partial curves separated from each other are curved or A curved line drawn by connecting straight lines and continuing smoothly 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 curve is
2t / 5 ≦ α ≦ 3t / 5
The oil pump rotor according to claim 1, wherein: 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,
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 displaced along the tangential direction drawn at the center point of the adductor cycloid curve, and then displaced along the circumferential direction of the base circle Di and separated, and these two internal tooth partial curves separated from each other are curved or A curved line drawn by connecting straight lines and continuing smoothly 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 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,
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,
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 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 displaced along the tangential direction drawn at the center point of the abduction cycloid curve, and then displaced along the circumferential direction of the base circle Di and separated, and the two external tooth partial curves separated from each other are curved or A curved line drawn by connecting straight lines and continuing smoothly is formed as a tooth profile,
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 displaced along the tangential direction drawn at the center point of the adductor cycloid curve, and then displaced along the circumferential direction of the base circle Di and separated, and these two internal tooth partial curves separated from each other are curved or A curved line drawn by connecting straight lines and continuing smoothly is formed as a tooth profile,
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
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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