JP2003322089A - Oil pump rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve quietness of an oil pump by properly setting profiles of teeth of an inner rotor and an outer rotor thereof and a space between both the rotors and reducing sliding resistance and rattle between the tooth surfaces of both the rotors. <P>SOLUTION: The inner rotor 10 having 'n' teeth is formed such that the tooth tip profile and tooth space profile thereof are formed by using cycloid curves which are formed by rolling a first circumscribed-rolling circle Ai and a first inscribed-rolling circle Bi along a base circle Di, respectively. The outer rotor 20 having 'n+1' teeth is formed such that the tooth tip profile and tooth space profile thereof are formed by using cycloid curves which are formed by rolling a second circumscribed-rolling circle Ao and a second inscribed-rolling circle Bo along a base circle Do, respectively. When the diameters of Di, Ai, Bi, Do, Ao and Bo are taken as ϕDi, ϕAi, ϕBi, ϕDo, ϕAo and ϕBo, respectively, and clearance is taken as t, each rotor 10 and 20 is constituted by satisfying ϕBo=ϕBi, ϕDo=(n+1).ϕDi/n+(n+1).t/(n+2), ϕAo=ϕAi+t/(n+2). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor for an oil pump that sucks and discharges fluid by changing the volume of cells formed between an inner rotor and an outer rotor.

[0002]

2. Description of the Related Art A conventional oil pump includes an inner rotor having n (n is a natural number) outer teeth, an outer rotor having (n + 1) inner teeth meshing with the outer teeth, and a fluid And a casing in which a discharge port for discharging the fluid is formed, and by rotating the inner rotor, the outer teeth mesh with the inner teeth to rotate the outer rotor, and between the rotors. The fluid is sucked and discharged by the volume change of the formed cells.

The cell has a front side and a rear side in the rotation direction,
The outer teeth of the inner rotor and the inner teeth of the outer rotor are in contact with each other, so that they are individually partitioned and both side surfaces are partitioned by a casing, thereby forming an independent fluid transfer chamber. Then, after the volume of each cell becomes the minimum during the process of meshing between the external teeth and the internal teeth, the volume is expanded when the cells move along the suction port to suck the fluid, and the volume becomes maximum. Then, the volume is reduced as it moves along the discharge port to discharge the fluid.

The oil pump having the above-described structure is widely used as a lubricating oil pump for automobiles, an oil pump for automatic transmissions, etc. because of its small size and simple structure. As a drive means of an oil pump mounted on a vehicle, there is a crankshaft direct coupling drive in which an inner rotor is directly coupled to a crankshaft of an engine and is driven by rotation of the engine.

With respect to the oil pump as described above, in order to reduce noise generated by the pump and to improve mechanical efficiency accompanied therewith, the inner rotor at a position rotated by 180 ° from the meshed position in a state where the inner rotor and the outer rotor are combined with each other. An appropriate size of tip clearance is set between the tip of the rotor and the tip of the outer rotor.

As means for ensuring the tip clearance, the tooth profiles of the outer rotor are evenly driven to provide clearances between the tooth surfaces of both rotors, and the tip clearances are secured between the tooth tips of both rotors in the meshed state. And those by flattening the cycloid curve.

By the way, the conditions necessary for determining the tooth profiles of the inner rotor and the outer rotor are as follows. First, for the inner rotor ri, the first abduction circle ai (diameter φa
i) and the rolling distance of the first adder circle bi (diameter φbi) must be closed in one round, that is, the first adder circle ai
And the integral multiple (the number of teeth times) of the sum of the rolling distances of the first adder circle bi is the basic circle di (diameter φdi) of the inner rotor ri.
Since it must be equal to the circumference of, φdi = n · (φai + φbi)

Similarly, for the outer rotor ro, an integer multiple (the number of teeth) of the rolling distance of the second abduction circle ao (diameter φao) and the second adduction circle bo (diameter φbo) is the outer rotor ro. Since it must be equal to the circumference of the basic circle do (diameter φdo), φdo = (n + 1) · (φao + φbo)

Next, since the inner rotor ri and the outer rotor ro mesh with each other, the eccentricity of both rotors is e
As φai + φbi = φao + φbo = 2e

From the above equations, (n + 1) φdi = nφdo, and the inner rotor ri and the outer rotor ro are
The tooth profile of is configured to satisfy these conditions.

Here, in order to divide the clearance = s into the clearance between the tooth groove and the tooth tip at the meshing position and the clearance between the tooth tips at a position rotated 180 ° from the meshing position (tip clearance), φao = Each abduction circle and adduction circle is configured so as to satisfy φai + s / 2 and φbo = φbi−s / 2. In other words, by increasing the outer rotation circle on the outer side, as shown in FIG.
A clearance s / 2 is created between the tooth groove of o and the tooth tip of the inner rotor ri, and the adder circle has a smaller inner side, so that the tooth tip of the outer rotor ro at the meshing position as shown in FIG. A clearance s / 2 is created between the tooth gap and the tooth groove of the inner rotor ri (see, for example, Patent Document 1).

An oil pump rotor constructed so as to satisfy the above relationships is shown in FIGS. 4 to 6. In this oil pump rotor, the basic circle di of the inner rotor ri is φdi = 5
2.00 mm, the first abduction circle ai is φai = 2.50 m
m, the first adduction circle bi is φbi = 2.70 mm, the number of teeth n =
10, outer diameter of outer rotor ro is φ70 mm, basic circle do is φdo = 57.20 mm, second outer circle ao is φa
o = 2.56 mm, the second adder circle bo is φbo = 2.64
mm, the number of teeth n + 1 = 11, and the amount of eccentricity e = 2.6 mm.

Between the outer teeth of the inner rotor and the inner teeth of the outer rotor, as shown in FIGS. 5 and 6, a radial clearance s1 at the center of the tooth tip and tooth groove is provided.
Not only is there a circumferential clearance s2 in the vicinity of the intersection of each base circle and the tooth surface.

[0014]

[Patent Document 1] JP-A-11-264381

[0015]

However, when the clearance s is formed by adjusting the diameters of the second outer rotation circle ao and the second inner rotation circle bo of the outer rotor as described above, the radial clearance s1 = If s / 2 is secured, the circumferential clearance s2 becomes large as shown in FIGS. 5 and 6, and the rattling of the outer rotor with respect to the inner rotor and the slip between the tooth surfaces become large, so that the torque transmission of There have been problems of increased loss, heat generation, and generation of noise due to impact between both rotors.

The present invention has been made in view of the above problems, and sets the tooth profile of the inner rotor and the tooth profile of the outer rotor in an appropriate shape in the process of meshing the rotors with each other, and a gap between the rotors. Is set appropriately and the sliding resistance and rattling between the tooth surfaces of both rotors are reduced to improve the quietness of the oil pump.

[0017]

In order to solve the above-mentioned problems, an oil pump rotor according to the invention of claim 1 meshes with an inner rotor having n outer teeth formed thereon (n + 1). An outer rotor having a sheet of internal teeth,
A casing having a suction port for sucking the fluid and a discharge port for discharging the fluid is formed, and when the rotors mesh with each other and rotate, the fluid is discharged by the volume change of the cells formed between the tooth surfaces of the rotors. In an oil pump rotor used for an oil pump that conveys fluid by sucking and discharging, the tooth profile of the inner rotor is an abduction cycloid curve created by a first abduction circle Ai that circumscribes the basic circle Di and rolls without slipping. Is the tooth profile of the tooth tip,
The first adder circle Bi that inscribes on the base circle Di and rolls without slipping
The adduction cycloid curve created by is formed as the tooth profile of the tooth groove, and the tooth profile of the outer rotor is the basic circle Do.
An abduction cycloidal curve created by a second abduction circle Ao that circumscribes the surface and has a tooth profile of the tooth groove, and an inversion created by a second abduction circle Bo that inscribes and rolls without slipping on the basic circle Do. The cycloid curve is formed as a tooth profile of the tooth tip, and the diameter of the basic circle Di of the inner rotor is φDi, the diameter of the first abduction circle Ai is φAi, the diameter of the first inversion circle Bi is φBi, and the foundation of the outer rotor is The diameter of the circle Do is φDo, the diameter of the second abduction circle Ao is φAo, the diameter of the second abduction circle Bo is φBo, and the size of the gap between the tooth tips of the inner rotor and the outer rotor is t (≠ 0), φBo = φBi and φDo = φDi · (n + 1) / n + t · (n + 1) /
(N + 2) φAo = φAi + t / (n + 2) is satisfied to configure the inner rotor and the outer rotor.

That is, in order to determine the tooth profile of the inner rotor and the outer rotor, first, since the rolling distances of the outer and inner rotating circles of the inner and outer rotors must be closed in one round, φDi = n. ( φAi + φBi) φDo = (n + 1) · (φAo + φBo) must be satisfied. Further, in the present invention, in order to reduce the circumferential clearance between the tooth groove of the inner rotor and the tooth tip of the outer rotor, the diameters of the inner circles of the inner rotor and the outer rotor are made the same. φBo = φBi

Under these conditions, the inner circle of the outer rotor becomes larger than that of the conventional one (φBi-t / 2). Therefore, in order to secure an appropriate clearance t, the basic circle of the outer rotor is the conventional one. (ΦDi · (n + 1) /
n). φDo = φDi · (n + 1) / n + (n + 1) · t /
(N + 2) If the outer circle of the outer rotor is adjusted to close the rolling distance of the outer circle and the inner circle with the change of the basic circle, φAo = φAi + t / (n + 2)

According to the present invention, the radial clearance between the outer teeth of the inner rotor and the inner teeth of the outer rotor is secured, and the circumferential clearance between the tooth flanks of each rotor is smaller than in the prior art. It is possible to realize an oil pump with low rattling and high quietness.

An oil pump rotor according to a second aspect of the present invention is the oil pump rotor of the first aspect, wherein the inner rotor and the outer rotor are set within a range of 0.03 mm ≦ t ≦ 0.25 mm (mm: millimeter). It is characterized in that the rotor is configured.

According to the present invention, the pressure pulsation, the cavitation noise, and the wear of the tooth surface are prevented by setting 0.03 mm≤t, and the volumetric efficiency is prevented from decreasing by setting t≤0.25 mm. You can

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS. The oil pump shown in FIG. 1 has an inner rotor 10 in which n (n is a natural number, n = 10 in this embodiment) outer teeth are formed.
And an outer rotor 20 having (n + 1) (n + 1 = 11 in the present embodiment) inner teeth formed to mesh with the outer teeth. The inner rotor 10 and the outer rotor 20 are provided inside the casing 50. It is stored.

Inner rotor 10, outer rotor 20
A plurality of cells C are formed between the tooth flanks along the rotation direction of the rotors 10 and 20. Each cell C has both rotors 1
The inner rotor 10 is provided on the front side and the rear side in the rotation direction of 0 and 20.
The outer teeth 11 and the inner teeth 21 of the outer rotor 20 are individually partitioned by contacting each other, and both side surfaces are partitioned by the casing 50, thereby forming an independent fluid transfer chamber. The cell C is rotationally moved with the rotation of both rotors 10 and 20, and the volume is repeatedly increased and decreased with one rotation as one cycle.

The inner rotor 10 is attached to a rotating shaft and is supported rotatably about an axis Oi, and is created by a first abduction circle Ai which circumscribes the basic circle Di of the inner rotor 10 and rolls without slipping. The abduction cycloidal curve is formed as the tooth profile of the tooth tip, and the abduction cycloidal curve created by the first abduction circle Bi inscribed in the basic circle Di and rolling without slipping is formed as the tooth profile of the tooth space.

The outer rotor 20 is arranged such that the axis Oo is eccentric (the amount of eccentricity: e) with respect to the axis Oi of the inner rotor 10, and is rotatably supported inside the casing 50 about the axis Oo. The outer rotor 20
Second abduction circle A that circumscribes the base circle Do of
The abduction cycloid curve created by o is the tooth profile of the tooth groove, and the abduction cycloid curve created by the second adduction circle Bo that is inscribed in the basic circle Do and rolls without slipping is formed as the tooth profile of the tooth tip. .

The diameter of the basic circle Di of the inner rotor 10 is φDi, the diameter of the first abduction circle Ai is φAi, and the first abduction circle B is
When the diameter of i is φBi, the diameter of the basic circle Do of the outer rotor 20 is φDo, the diameter of the second abduction circle Ao is φAo, and the diameter of the second inversion circle Bo is φBo, the inner rotor 1
The following relational expression holds between 0 and the outer rotor 20. In this case, the unit of measurement is mm (millimeter).
And

First, regarding the inner rotor 10,
The abduction circle Ai and the first abduction circle Bi must be closed in one rolling distance. That is, the sum of the integer multiples (the number of teeth times) of each rolling distance of the first abduction circle Ai and the first abduction circle Bi must be equal to the circumference of the basic circle Di, so that π · φDi = n · π · (φAi + φBi) That is, φDi = n · (φAi + φBi) (Ia) Similarly, for the outer rotor 20, the second outer rotation circle Ao.
And since the sum of the integer multiples (the number of teeth times) of each rolling distance of the second adder circle Bo must be equal to the circumference of the basic circle Do, π · φDo = (n + 1) · π · (φAo + φBo) , ΦDo = (n + 1) · (φAo + φBo) (Ib)

Next, regarding the outer rotor 20, the outer rotor ro (second outer circle a
The conditions for determining the tooth profile of the outer rotor 20 of the present embodiment will be described based on o (diameter φao), second adduction circle bo (diameter φbo), basic circle do (diameter φdo)). The outer rotor ro is disposed eccentrically with respect to the inner rotor 10 of the present embodiment (eccentricity e), meshes with a clearance t, and as described above, φdo = φDi · (n + 1) / n ... (II) and φdo = (n + 1) · (φao + φbo) (III) φao = φAi + t / 2 (IIIa) φbo = φBi-t / 2 (IIIb). The inner rotor 10 that meshes with the outer rotor ro satisfies the general relational expression φai + φbi = φAi + φBi = 2e (1) φDi = φdo-2e (2).

In the present embodiment, in order to reduce the circumferential clearance t2 between the tooth tips of the outer rotor 20 and the tooth grooves of the inner rotor 10 at the meshing position and to secure the radial clearance t1, φBo = φbi = φBi (IV) Further, from this equation (VI) and equation (1), φai = φAi (3) When the inner circle of the outer rotor 20 is set in this way, t = (φDo−φBo + φAo) − (ΦDi + φAi +
The clearance t, which is φAi), becomes t = (φDo−φdo) + (φAo−φai) (V) from Equations (1) to (3) and Equation (IV). The above formulas (Ib), (III), (IV),
From (V), t = (φAo−φai) · (n + 2) (VI), so φAo = φai + t / (n + 2).

First, the diameter φDo of the basic circle Do is obtained. From (Ib) and (III), φDo−φdo = (n + 1) · (φAo + φBo) −
(N + 1) · (φao + φbo), and further (IIIa), (IIIb), (I
V) φDo−φdo = (n + 1) · (φAo−φai) (VII) From (VI) to (VII) becomes φDo−φdo = (n + 1) · t / (n + 2). , ΦDo is φDo = (n + 1) · φDi / n + (n + 1) · t / (n + 2) (A)

Next, from (Ib) φAo = φDo / (n + 1) −φBo Therefore, according to (A) φAo = φDi / n + t / (n + 2) −φBo From (Ia) and (IV) φAo = φAi + t / (n + 2) (B)

Summarizing the above equations, the outer rotor 20 has a φBo = φbi = φBi (IV) φDo = (n + 1) · φDi / n + (n + 1) · t / (n + 2) (A) φAo = φAi + t / (N + 2) (B) is satisfied.

FIG. 1 shows an inner rotor 10 (having a basic circle Di of φDi = 52.00) constructed to satisfy the above relationship.
mm, the first abduction circle Ai is φAi = 2.50 mm, the first abduction circle Bi is φBi = 2.70 mm, the number of teeth n = 10, and the outer rotor 20 (outer diameter φ70 mm, basic circle Do)
Is φDo = 57.31 mm, and the second abduction circle Ao is φAo =
2.51 mm, the second adder circle Bo is φBo = 2.70 m
m) is clearance t = 0.12 mm, eccentricity e = 2.
6 shows an oil pump rotor combined at 6 mm.

The casing 50 includes both rotors 10 and 20.
Among the cells C formed between the tooth flanks, an arc-shaped suction port (not shown) is formed along the cell C whose volume is increasing, and the cell C whose volume is decreasing is formed.
A discharge port (not shown) having an arc shape is formed along the line.

The cell C expands its volume as it moves along the suction port after the volume becomes a minimum during the meshing process of the outer teeth 11 and the inner teeth 21, and the fluid is sucked in by the volume. After the maximum, the volume is reduced and the fluid is discharged as it moves along the discharge port.

If the clearance t is too small, pressure pulsation occurs in the fluid squeezed out of the cell C whose volume is decreasing, cavitation noise is generated, the operating noise of the pump is increased, and the pressure pulsation causes both rotors to rotate. Will not rotate smoothly. On the other hand, if the clearance t is too large, the pressure pulsation of the fluid does not occur, the operating noise is reduced, and the backlash is increased, so that the sliding resistance between the tooth flanks is reduced and the mechanical efficiency is improved. The liquid tightness in the cell C is impaired, and the pump performance, especially the volume efficiency is deteriorated. Moreover, the transmission of the drive torque at the correct meshing position is not performed,
Since the loss of rotation increases, the mechanical efficiency also decreases. Therefore, the clearance t is 0.03 mm ≦ t
It is preferable to set the range to satisfy ≦ 0.25 mm, and the most preferable value is 0.12 mm in the present embodiment.

By the way, in the oil pump rotor configured as described above, the above formulas (IV), (A),
By satisfying the relationship of (B), as shown in FIG.
The tooth profile of the tips of the outer rotor 20 is the inner rotor 10.
The tooth profile of the tooth groove is almost the same. As a result,
As shown in, the circumferential clearance t2 is reduced while the radial clearance t1 at the meshing position is kept at t / 2 = 0.06 mm, which is the same as the conventional clearance.
The impact that the rotors 10 and 20 receive when rotating is small. Further, since the pressure direction at the time of meshing is perpendicular to the tooth surface, torque transmission between the rotors 10 and 20 is performed with high efficiency without slippage, and heat generation and noise due to sliding resistance are reduced.

FIG. 3 shows a graph comparing the noise generated when the oil pump rotor according to the prior art is used with the noise generated when the oil pump rotor according to the present embodiment is used. From this graph, it can be seen that the oil pump rotor according to the present embodiment has lower noise and higher quietness than the conventional one.

[0040]

As described above, according to the oil pump rotor of the first aspect, the inner circle of the outer rotor has the same diameter as the inner circle of the inner rotor, so that the radial clearance is secured. In addition, since the circumferential clearance can be made smaller than before, it is possible to realize an oil pump with less rattling of both rotors and high quietness.

According to the oil pump rotor of the second aspect of the present invention, by setting 0.03 mm ≦ t, pressure pulsation, cavitation noise, and tooth surface wear can be prevented, and by setting t ≦ 0.25 mm. It is possible to prevent a decrease in volumetric efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of an oil pump rotor according to the present invention, in which an inner rotor and an outer rotor are φBo = φBi and φDo = φDi · (n + 1) / n + t · (n + 1) /
(N + 2) is a plan view showing an oil pump that satisfies the relationship of φAo = φAi + t / (n + 2) and is configured such that the value of t is set to t = 0.12 mm 2.

FIG. 2 is an enlarged view of a II portion showing a meshing portion of the oil pump shown in FIG.

FIG. 3 is a graph showing a comparison between the noise caused by the oil pump shown in FIG. 1 and the noise caused by the conventional oil pump.

FIG. 4 is a diagram showing a conventional oil pump rotor, in which an inner rotor and an outer rotor have φdi = n · (φai + φbi) and φdo = (n + 1).
・ (Φao + φbo) (n + 1) ・ φdi = n ・ φdo φao = φai + s / 2, φbo = φbi-s / 2, and the value of s is set to s = 0.12 mm. FIG.

5 is an enlarged view of a V portion showing a meshing portion of the oil pump shown in FIG.

6 is an enlarged view showing a meshing portion of the oil pump shown in FIG. 4 and showing a state in which a tooth tip of an outer rotor and a tooth groove of an inner rotor are meshed with each other.

[Explanation of symbols]

10 Inner rotor 11 external teeth 20 Outer rotor 21 internal teeth 50 casing Ai Inner rotor abduction circle (first abduction circle) Ao Outer rotor abduction circle (second abduction circle) Bi Inner rotor adduction circle (first addition circle) Bo Outer rotor adduction circle (second adduction circle) C cell Di Inner rotor basic circle Do Outer rotor basic circle Oi Inner rotor shaft center Oo Outer rotor axis

Claims (2)

[Claims] 1. An inner rotor having n outer teeth formed therein, an outer rotor having (n + 1) inner teeth meshing with the outer teeth, an intake port for sucking fluid, and a fluid discharged. And a casing in which a discharge port is formed, and when both rotors mesh and rotate, an oil pump that conveys the fluid by sucking and discharging the fluid due to the volume change of cells formed between the tooth surfaces of the rotors. In the oil pump rotor used for, the tooth profile of the inner rotor has an abduction cycloidal curve created by the first abduction circle Ai circumscribing the basic circle Di and rolling without slipping, and the tooth profile of the tooth tip is The adder cycloid curve created by the first adder circle Bi that contacts and rolls without slipping is formed as the tooth profile of the tooth groove, and the tooth profile of the outer rotor is the basic circle D. An abduction cycloidal curve created by a second abduction circle Ao that circumscribes the surface and has a tooth profile of the tooth groove, and an inversion created by a second abduction circle Bo that inscribes and rolls without slipping on the basic circle Do. The cycloid curve is formed as the tooth profile of the tooth tip, and the diameter of the basic circle Di of the inner rotor is φDi, the diameter of the first abduction circle Ai is φAi, and the diameter of the first abduction circle Bi is φBi,
The diameter of the basic circle Do of the outer rotor is φDo, the diameter of the second abduction circle Ao is φAo, and the diameter of the second inversion circle Bo is φB.
o, where the size of the gap between the tooth tips of the inner rotor and the outer rotor is t (≠ 0), φBo = φBi and φDo = φDi · (n + 1) / n + t · (n + 1) /
An oil pump rotor characterized in that an inner rotor and an outer rotor are formed by satisfying (n + 2) φAo = φAi + t / (n + 2). 2. The oil pump rotor according to claim 1, wherein the inner rotor and the outer rotor are configured within a range of 0.03 mm ≦ t ≦ 0.25 mm (mm: millimeter). Characteristic oil pump rotor.