JP3860125B2 - Oil pump rotor - Google Patents

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]
A conventional 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 suction 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 parts formed between the rotors. Fluid is sucked and discharged by changing the volume of the cell.
[0003]
The cells are individually partitioned by the contact between the outer teeth of the inner rotor and the inner teeth of the outer rotor on the front side and the rear side in the rotation direction, and both sides are partitioned by a casing. The fluid transfer chamber is configured. Then, after the volume of each cell is minimized during the process of meshing between the external teeth and the internal teeth, the volume is expanded when moving along the suction port, and the volume is maximized. After that, when moving along the discharge port, the volume is reduced and the fluid is discharged.
[0004]
The oil pump having the above-described configuration is widely used as a lubricating oil pump for an automobile, an oil pump for an automatic transmission, and the like because of its small size and simple structure. As a drive means of the oil pump when mounted on an automobile, there is a crankshaft direct connection drive in which an inner rotor is directly connected to an engine crankshaft and driven by the rotation of the engine.
[0005]
For the oil pump as described above, the teeth of the inner rotor at a position rotated 180 ° from the meshing position in a state where the inner rotor and the outer rotor are combined for the purpose of reducing the noise generated by the pump and improving the mechanical efficiency associated therewith. A chip clearance of an appropriate size is set between the tip and the tooth tip of the outer rotor.
[0006]
As means for ensuring the tip clearance, a clearance is provided between the tooth surfaces of both rotors by uniformly driving in the tooth profile of the outer rotor, and a tip clearance is ensured between the tooth tips of both rotors in a meshed state, cycloid The thing by the flattening of a curve etc. are mentioned.
[0007]
By the way, the conditions necessary for determining the tooth profiles of the inner rotor and the outer rotor are first the rolling of the first abduction circle ai (diameter φai) and the first inversion circle bi (diameter φbi) for the inner rotor ri. The distance must be closed in one turn, that is, an integral multiple (number of teeth) of the sum of the rolling distances of the first abduction circle ai and the first addition circle bi is the basic circle di (diameter φdi) of the inner rotor ri. Because it must be equal to the circumference,
φdi = n · (φai + φbi)
[0008]
Similarly, for the outer rotor ro, an integral multiple (number of teeth times) of the sum of the rolling distances of the second abduction circle ao (diameter φao) and the second inversion circle bo (diameter φbo) is the basic circle do of the outer rotor ro. Since it must be equal to the circumference of (diameter φdo),
φdo = (n + 1) · (φao + φbo)
[0009]
Next, since the inner rotor ri and the outer rotor ro mesh with each other, the eccentric amount of both rotors is represented as e.
φai + φbi = φao + φbo = 2e
[0010]
From the above equations, (n + 1) · φdi = n · φdo
Thus, the tooth profiles of the inner rotor ri and the outer rotor ro are configured to satisfy these conditions.
[0011]
Here, in order to distribute the clearance = s to the clearance between the tooth gap and the tooth tip at the meshing position and the clearance between the tooth tips (tip clearance) at a position rotated by 180 ° from the meshing position,
φao = φai + s / 2, φbo = φbi−s / 2
Each abduction circle and adduction circle are configured to satisfy
That is, by increasing the outer rotation circle on the outer side, a clearance s / 2 is created between the tooth groove of the outer rotor ro and the tooth tip of the inner rotor ri at the meshing position as shown in FIG. By reducing the inner side of the circle, a clearance s / 2 is created between the tooth tip of the outer rotor ro and the tooth groove of the inner rotor ri at the meshing position as shown in FIG. 6 (see, for example, Patent Document 1). ).
[0012]
An oil pump rotor configured to satisfy the above relationship is shown in FIGS. In this oil pump rotor, the basic circle di of the inner rotor ri is φdi = 52.00 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. The outer diameter of the outer rotor ro is φ70 mm, the base circle do is φdo = 57.20 mm, the second abduction circle ao is φao = 2.56 mm, the second addendum circle bo is φbo = 2.64 mm, the number of teeth n + 1 = 11, eccentricity e = 2.6 mm.
[0013]
Between the outer teeth of the inner rotor and the inner teeth of the outer rotor, as shown in FIGS. 5 and 6, not only the radial clearance s1 at the center of the tooth tip and the tooth gap but also each basic circle and tooth. A circumferential clearance s2 near the intersection with the surface is also formed.
[0014]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-264381
[Problems to be solved by the invention]
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 in this way, if the radial clearance s1 = s / 2 is secured, FIG. As shown in FIG. 6, the circumferential clearance s2 becomes large, and the outer rotor rattling with respect to the inner rotor and slippage between the tooth surfaces become large, increasing torque transmission loss and heat generation, and between the two rotors. The generation of noise due to the impact of this was a problem.
[0016]
The present invention has been made in view of such problems, and sets the tooth profile of the inner rotor and the tooth profile of the outer rotor to an appropriate shape while the rotors are engaged with each other, and appropriately sets the gap between the rotors. The purpose is to improve the quietness of the oil pump by reducing the sliding resistance and rattling between the tooth surfaces of both rotors.
[0017]
[Means for Solving the Problems]
In order to solve the above-described problem, an oil pump rotor according to the invention of claim 1 includes an inner rotor formed with n external teeth and (n + 1) internal teeth that mesh with the external teeth. A volume of a cell formed between the tooth surfaces of both rotors, comprising an outer rotor and a casing in which a suction port for sucking fluid and a discharge port for discharging fluid are formed, and the rotors mesh with each other and rotate. In an oil pump rotor used in an oil pump that conveys fluid by sucking and discharging fluid by change, the tooth profile of the inner rotor is created by a first abduction circle Ai that circumscribes the base circle Di and rolls without sliding. An abductor cycloid curve is created by a first addendum circle Bi that is inscribed in the base circle Di and rolls without slipping. The tooth profile of the outer rotor is formed by the second abduction circle Ao that circumscribes the base circle Do and rolls without slipping, and the tooth profile of the outer groove is inscribed in the base circle Do. An addendum cycloid curve created by the second addendum circle Bo that rolls without slipping is formed as a tooth shape of the tooth tip, 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 addendum circle Bi is φBi, the diameter of the base circle Do of the outer rotor is φDo, the diameter of the second abduction circle Ao is φAo, the diameter of the second addendum circle Bo is φBo, (φDo−φBo + φAo) − When the clearance between the inner rotor and the outer rotor represented by (φDi + φAi + φAi) is t (≠ 0),
φBo = φBi and φDo = φDi · (n + 1) / n + t · (n + 1) / (n + 2)
The inner rotor and the outer rotor are configured to satisfy φAo = φAi + t / (n + 2).
[0018]
That is, in order to determine the tooth profile of the inner rotor and outer rotor, first, the rolling distance of the outer and inner rotation circles of the inner rotor and outer rotor must be closed in one round.
φDi = n · (φAi + φBi)
φDo = (n + 1) ・ (φAo + φBo)
It is necessary to satisfy each formula of
Furthermore, 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 rotation circles of the inner rotor and the outer rotor are made the same.
φBo = φBi
[0019]
Under these conditions, the inner rotation circle of the outer rotor becomes larger than the conventional one (φBi−t / 2). Therefore, in order to ensure an appropriate clearance t, the outer rotor base circle is the conventional one (φDi · (N + 1) / n).
φDo = φDi · (n + 1) / n + (n + 1) · t / (n + 2)
When adjusting the outer rotor abduction circle to close the rolling distance of the abduction circle and the inversion circle with the change of the base circle,
φAo = φAi + t / (n + 2)
[0020]
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 ensured, and the circumferential clearance between the tooth surfaces of each rotor is smaller than in the prior art. It is possible to realize an oil pump that is small in roughness and highly quiet.
[0021]
An oil pump rotor according to the invention of claim 2 is the oil pump rotor of claim 1,
0.03 mm ≦ t ≦ 0.25 mm (mm: millimeter)
It is characterized in that the inner rotor and the outer rotor are configured after being set in the range of.
[0022]
According to the present invention, pressure pulsation, cavitation noise, and tooth surface wear can be prevented by setting 0.03 mm ≦ t, and a decrease in volumetric efficiency can be prevented by setting t ≦ 0.25 mm.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. The oil pump shown in FIG. 1 has an inner rotor 10 formed with n (n is a natural number, n = 10 in this embodiment) outer teeth and meshes with each outer tooth (n + 1) (in this embodiment). n + 1 = 11) outer rotors 20 having inner teeth formed therein, and the inner rotor 10 and the outer rotor 20 are housed inside the casing 50.
[0024]
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 a casing 50, thereby forming an independent fluid transfer chamber. The cell C rotates and moves with the rotation of the rotors 10 and 20, and repeats the increase and decrease in volume with one rotation as one cycle.
[0025]
The inner rotor 10 is attached to a rotary shaft and is supported so as to be rotatable about an axis Oi. The inner rotor 10 is formed by a first abduction circle Ai that circumscribes the basic circle Di of the inner rotor 10 and rolls without sliding. An inversion cycloid curve formed by a first addendum circle Bi inscribed in the base circle Di and slipping without slipping is formed as a tooth profile of the tooth gap.
[0026]
The outer rotor 20 is arranged with the axis Oo eccentrically (eccentric amount: e) with respect to the axis Oi of the inner rotor 10, and is rotatably supported in the casing 50 around the axis Oo. The abduction cycloid curve created by the second abduction circle Ao that circumscribes the base circle Do of the outer rotor 20 and rolls without slipping is defined as the tooth profile of the tooth groove, and the second inversion circle that inscribes the base circle Do and rolls without slipping. An adductor cycloid curve created by Bo is formed as the tooth profile of the tooth tip.
[0027]
The diameter of the base circle Di of the inner rotor 10 is φDi, the diameter of the first abduction circle Ai is φAi, the diameter of the first abduction circle Bi is φBi, the diameter of the base circle Do of the outer rotor 20 is φDo, and the second abduction When the diameter of the circle Ao is φAo and the diameter of the second addendum circle Bo is φBo, the following relational expression holds between the inner rotor 10 and the outer rotor 20. Here, the unit of dimension is mm (millimeter).
[0028]
First, with respect to the inner rotor 10, the rolling distance of the first outer rotation circle Ai and the first inner rotation circle Bi must be closed in one round. That is, since the sum of the integral multiples (number of teeth times) of the respective rolling distances of the first abduction circle Ai and the first addition circle Bi must be equal to the circumference of the basic circle Di,
π · φDi = n · π · (φAi + φBi)
That is, φDi = n · (φAi + φBi) (Ia)
Similarly, for the outer rotor 20, the sum of integer multiples (number of teeth times) of the respective rolling distances of the second abduction circle Ao and the second addition circle Bo must be equal to the circumference of the basic circle Do.
π · φDo = (n + 1) · π · (φAo + φBo)
That is, φDo = (n + 1) · (φAo + φBo) (Ib)
[0029]
Next, the outer rotor 20 is based on the outer rotor ro (second abduction circle ao (diameter φao), second inversion circle bo (diameter φbo), basic circle do (diameter φdo)) described as the prior art. The conditions for determining the tooth profile of the outer rotor 20 of this embodiment will be described.
The outer rotor ro is arranged eccentrically with respect to the inner rotor 10 of the present embodiment (eccentric amount e) and meshes with a clearance t, and φdo = φDi · (n + 1) / n as described above. (II)
And φdo = (n + 1) · (φao + φbo) (III)
φao = φAi + t / 2 (IIIa)
φbo = φBi−t / 2 (IIIb)
Shall be satisfied.
For the inner rotor 10 meshing with the outer rotor ro, the general relational expression φai + φbi = φAi + φBi = 2e (1)
φDi = φdo-2e (2)
Meet.
[0030]
In the present embodiment, in order to reduce the circumferential clearance t2 between the tooth tip of the outer rotor 20 and the tooth groove of the inner rotor 10 at the meshing position, and to secure the radial clearance t1,
φBo = φbi = φBi (IV)
From the formula (VI) and the formula (1),
φai = φAi (3)
When the inner rotation circle of the outer rotor 20 is set in this way,
t = (φDo−φBo + φAo) − (φDi + φAi + φAi)
The clearance t, which is: from the formulas (1) to (3) and the formula (IV),
t = (φDo−φdo) + (φAo−φai) (V)
It becomes.
From the above formulas (Ib), (III), (IV), (V),
t = (φAo−φai) · (n + 2) (VI)
Because
φAo = φai + t / (n + 2)
It becomes.
[0031]
Here, the diameter φDo of the basic circle Do is first obtained. From (Ib) and (III), φDo−φdo = (n + 1) · (φAo + φBo) − (n + 1) · (φao + φbo)
Further, φDo−φdo = (n + 1) · (φAo−φai) (VII) from (IIIa), (IIIb), and (IV).
(VI) to (VII) are φDo−φdo = (n + 1) · t / (n + 2)
Therefore, from (II), φDo becomes φDo = (n + 1) · φDi / n + (n + 1) · t / (n + 2) (A)
[0032]
Next, from (Ib) to φAo = φDo / (n + 1) −φBo
Therefore, according to (A), φAo = φDi / n + t / (n + 2) −φBo
Further, from (Ia) and (IV), φAo = φAi + t / (n + 2) (B)
[0033]
Summarizing the above equations, the outer rotor 20 is
φBo = φbi = φBi (IV)
φDo = (n + 1) · φDi / n + (n + 1) · t / (n + 2) (A)
φAo = φAi + t / (n + 2) (B)
It is configured to satisfy.
[0034]
FIG. 1 shows an inner rotor 10 configured to satisfy the above relationship (basic circle Di is φDi = 52.00 mm, first abduction circle Ai is φAi = 2.50 mm, and first inversion circle Bi is φBi = 2. .70 mm, number of teeth n = 10) and outer rotor 20 (outer diameter is φ70 mm, basic circle Do is φDo = 57.31 mm, second abduction circle Ao is φAo = 2.51 mm, and second addendum circle Bo is φBo = 2.70 mm) shows an oil pump rotor combined with a clearance t = 0.12 mm and an eccentricity e = 2.6 mm.
[0035]
The casing 50 is formed with an arc-shaped suction port (not shown) along the cell C whose volume is increasing among the cells C formed between the tooth surfaces of the rotors 10 and 20. An arc-shaped discharge port (not shown) is formed along the cell C whose volume is decreasing.
[0036]
The cell C has a minimum volume during the process of meshing between the outer teeth 11 and the inner teeth 21, and then expands the volume when moving along the suction port to suck in the fluid. Then, when moving along the discharge port, the volume is reduced and the fluid is discharged.
[0037]
If the clearance t is too small, pressure pulsation is generated in the fluid squeezed out from the cell C whose volume is decreasing, cavitation noise is generated, pump operating noise is increased, and both rotors are rotated by the pressure pulsation. It will not be performed smoothly.
On the other hand, if the clearance t is too large, the pressure pulsation of the fluid does not occur and the operation noise is reduced, and the backlash is increased, so that the sliding resistance between the tooth surfaces is reduced and the mechanical efficiency is improved. The liquid tightness in the cell C is impaired, and the pump performance, particularly volumetric efficiency, is deteriorated. In addition, the transmission of drive torque at the correct meshing position is not performed, and the loss of rotation increases, so that the mechanical efficiency is also lowered.
Therefore, the clearance t is preferably in a range satisfying 0.03 mm ≦ t ≦ 0.25 mm, and is most preferably 0.12 mm in the present embodiment.
[0038]
By the way, in the oil pump rotor comprised as mentioned above, by satisfy | filling the relationship of the said Formula (IV), (A), (B), as shown in FIG. Is substantially equal to the tooth profile of the tooth groove of the inner rotor 10. As a result, as shown in FIG. 2, the radial clearance t1 at the meshing position is kept at t / 2 = 0.06 mm, which is the same as the conventional one, and the circumferential clearance t2 becomes small. The impact which 20 receives mutually 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 slipping, and heat generation and noise due to sliding resistance are reduced.
[0039]
FIG. 3 shows a graph comparing the noise generated when the oil pump rotor according to the prior art is used and 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 conventional ones.
[0040]
【The invention's effect】
As described above, according to the oil pump rotor of the first aspect, the inner rotor circle of the outer rotor has the same diameter as the inner rotor circle of the inner rotor, thereby ensuring the radial clearance while ensuring the radial clearance. Since the clearance can be made smaller than before, it is possible to realize an oil pump with low noise and high quietness of both rotors.
[0041]
According to the oil pump rotor of the second aspect of the present invention, pressure pulsation, cavitation noise, and tooth surface wear can be prevented by setting 0.03 mm ≦ t, and volume efficiency can be improved by setting t ≦ 0.25 mm. A decrease can be prevented.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of an oil pump rotor according to the present invention, wherein an inner rotor and an outer rotor are
φBo = φBi
And φDo = φDi · (n + 1) / n + t · (n + 1) / (n + 2)
φAo = φAi + t / (n + 2)
And the value of t is t = 0.12 mm
It is a top view which shows the oil pump comprised by setting to.
FIG. 2 is an enlarged view of a portion II showing a meshing portion of the oil pump shown in FIG.
FIG. 3 is a graph showing a comparison between noise from the oil pump shown in FIG. 1 and noise from a conventional oil pump.
FIG. 4 is a view showing a conventional oil pump rotor, in which an inner rotor and an outer rotor are
φdi = n · (φai + φbi), φdo = (n + 1) · (φao + φbo)
(N + 1) · φdi = n · φdo
φao = φai + s / 2, φbo = φbi−s / 2
And the value of s is s = 0.12mm
It is a top view which shows the oil pump comprised by setting to.
FIG. 5 is an enlarged view of a V portion showing a meshing portion of the oil pump shown in FIG. 4;
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 meshes with a tooth groove of an inner rotor.
[Explanation of symbols]
10 Inner rotor 11 Outer teeth 20 Outer rotor 21 Inner teeth 50 Casing Ai Inner rotor abduction circle (first abduction circle)
Ao Outer rotor abduction circle (second abduction circle)
Bi Inner rotor inversion circle (first inversion circle)
Bo Addendum circle of outer rotor (second addendum circle)
C Cell Di Inner rotor base circle Do Outer rotor base circle Oi Inner rotor axis Oo Outer rotor axis

Claims (2)

An inner rotor formed with n outer teeth, an outer rotor formed with (n + 1) inner teeth meshing with the outer teeth, a suction port for sucking fluid and a discharge port for discharging fluid are formed. And an oil pump used for an oil pump that conveys fluid by sucking and discharging fluid by changing the volume of a cell formed between the tooth surfaces of both rotors when both rotors mesh with each other and rotate In the rotor
The tooth profile of the inner rotor is the abduction cycloid curve created by the first abduction circle Ai that circumscribes the base circle Di and rolls without slipping. An abduction cycloid curve created by the second abduction circle Ao formed by the addendum cycloid curve created by the rolling circle Bi as the tooth profile of the tooth gap and the tooth profile of the outer rotor circumscribing the base circle Do and slipping. Is formed as a tooth profile of the addendum cycloid curve created by the second addendum circle Bo inscribed in the basic circle Do and slipping without slipping,
The diameter of the base 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, the diameter of the base circle Do of the outer rotor is φDo, and the second abduction circle Ao ΦAo, the diameter of the second addendum circle Bo is φBo, and the clearance between the inner rotor and the outer rotor represented by (φDo−φBo + φAo) − (φDi + φAi + φAi) is t (≠ 0),
φBo = φBi and φDo = φDi · (n + 1) / n + t · (n + 1) / (n + 2)
An oil pump rotor characterized in that an inner rotor and an outer rotor are configured to satisfy φAo = φAi + t / (n + 2). The oil pump rotor according to claim 1,
An oil pump rotor, wherein an inner rotor and an outer rotor are configured after being set in a range of 0.03 mm ≦ t ≦ 0.25 mm (mm: millimeter).

Images