JPH09256964A - Oil pump rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a mechanical loss due to slide resistance between an outer rotor and a casing, by forming an external tooth of an inner rotor along an envelope drawn by a generate circle group positioning the center on a trochoid curve generated with a relation of an addendum circle diameter of the external tooth and a generate circle radius in a specific range. SOLUTION: An inner rotor having n teeth of external teeth and an outer rotor having n+1 teeth of internal teeth, meshed with this inner rotor, are provided in a casing. An axial center O1 of the inner rotor is supported to the center, in its external tooth 11, when assuming D(mm) for diameter of an addendum circle P connecting an addendum of each external tooth 11 and R(mm) for radius of a generate circle Q, in a range satisfying a formula: 0.15<=n.R/(π.D)<=0.25, a trochoid curve t is generated, the external tooth is formed along an envelope h drawn by a generate circle group positioning the center on the trochoid curve t. In a shape of the inner rotor, an area of an internal tooth of the outer rotor is lessened, as a result, a mechanical loss generated between the outer rotor and the casing is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil pump rotor that sucks and discharges fluid by changing the volume of cells formed between the tooth surfaces of both rotors when the inner rotor and the outer rotor rotate in mesh with each other. It is a thing.

[0002]

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

The cells are individually partitioned on the front side and the rear side in the direction of rotation by contact between the outer teeth of the inner rotor and the inner teeth of the outer rotor, and both sides are partitioned by a casing. This constitutes 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.

[0004]

By the way, in the oil pump having the oil pump rotor as described above, the gap between each end surface of the inner rotor and the outer rotor and the casing, and the gap between the outer periphery of the outer rotor and the casing are always maintained. The outer teeth of the inner rotor and the inner teeth of the outer rotor are always in sliding contact before and after each cell. This is an important condition for maintaining the liquid tightness of the cell that conveys the fluid, but on the other hand, if the resistance generated in each sliding contact part is large, the mechanical loss of the oil pump will significantly increase, It has been an issue to reduce the resistance generated in each sliding contact portion.

The present invention has been made in view of the above circumstances, and an object thereof is to improve mechanical efficiency while ensuring durability and reliability as an oil pump.

[0006]

As means for solving the above problems, in the oil pump rotor of the present invention, the outer teeth of the inner rotor, the tip circle diameter of the inner rotor, and the creation circle radius are D ( mm) and R (mm), the generation circle group whose center is located on the trochoidal curve created in the range satisfying the following expression 0.15 ≦ n · R / (π · D) ≦ 0.25 Form along the drawn envelope. Further, the shape of the inner teeth of the outer rotor is determined according to the shape of the inner rotor, and like the shape of the outer teeth of the inner rotor, the shape is formed along the envelope drawn by the generation circle group whose center is located on the trochoid curve. . As a result, the area of the inner tooth end surface of the outer rotor is reduced to the extent that the inner teeth are not easily damaged, and the sliding area of the outer rotor as a whole is reduced.

Here, the envelope drawn by a group of generating circles whose center is located on the trochoidal curve created in the range satisfying the following expression n · R / (π · D)> 0.25 If formed along the line, the end surface area of the inner teeth of the outer rotor becomes larger than the end surface area of the outer teeth of the inner rotor, and the sliding area of the outer rotor with respect to the casing becomes large.

The outer teeth of the inner rotor are along the envelope drawn by the group of generating circles whose center is located on the trochoidal curve created in the range satisfying the following expression n.R / (. Pi.D) <0.15. If the outer rotor inner teeth are smaller than the inner rotor outer teeth, the outer rotor inner teeth end surface area becomes smaller and the outer rotor sliding surface area becomes smaller. The width of the teeth becomes narrow.

Further, in this oil pump rotor, a relief portion which is not in contact with the inner teeth of the outer rotor is provided on the front side in the rotation direction of the outer teeth of the inner rotor, so that the cell moves along the suction port. The inner rotor and the outer rotor do not come into contact with each other in the process of increasing the volume thereof.

Further, by providing an escape portion which is not in contact with the inner teeth of the outer rotor on the rear side in the rotation direction of the outer teeth of the inner rotor, the cell moves along the suction port and its volume increases. The inner rotor and the outer rotor do not come into contact with each other even during the process and the process in which the cell moves along the discharge port and the volume decreases, and the process in which the outer teeth of the inner rotor mesh with the inner teeth of the outer rotor, and the maximum volume The inner rotor and the outer rotor come into contact with each other only in the process in which the broken cells move from the suction port side to the discharge port side.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of an oil pump rotor according to the present invention will be described with reference to the drawings. The oil pump rotor shown in FIG. 1 has an inner rotor 10 having n (n is a natural number, n = 10 in the present embodiment) outer teeth, and n + 1 inner teeth meshing with the outer teeth. The inner rotor 10 and the outer rotor 20 are housed inside a casing 30.

The inner rotor 10 is attached to a rotary shaft and is rotatably supported about an axis O ₁ . As shown in FIG. 2, the outer teeth 11 of the inner rotor 10 have a diameter of a tip circle P connecting the tips of the outer teeth 11 with D (m
m), when the radius of the creation circle Q is R (mm), the center is on the trochoidal curve t created in the range that satisfies the following expression 0.15 ≦ n · R / (π · D) ≦ 0.25. Is formed along the envelope h drawn by the group of generating circles. (In Fig. 1, when nR / (πD) = 0.2)

[0013] The outer rotor 20 is eccentric to the axis O ₂ with respect to the axis O ₁ of the inner rotor 10 (eccentricity: e) to so arranged, it is rotatably supported about the axis O ₂ . Similarly to the outer teeth 11 of the inner rotor 10, the inner teeth 21 of the outer rotor 20 are also formed along the envelope drawn by the generation circle group whose center is located on the trochoid curve.

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 30, thereby forming an independent fluid transfer chamber. The cell C is rotationally moved as the rotors 10 and 20 rotate, and the volume is repeatedly increased and decreased with one rotation as one cycle.

The casing 30 includes both rotors 10 and 20.
Among the cells C formed between the tooth flanks, the arc-shaped suction port 31 is formed along the cell C whose volume is increasing, and the arc-shaped suction port 31 is formed along the cell C whose volume is decreasing. Discharge port 32 is formed.

After the volume of the cell C is minimized during the process of meshing between the outer teeth 11 and the inner teeth 21, the cell C expands its volume as it moves along the suction port 31, and sucks fluid. After the volume is maximized, the volume is reduced and the fluid is ejected when moving along the ejection port 32.

By the way, in the oil pump rotor constructed as described above, when the rotors 10 and 20 are rotated against the sliding resistance generated between the end surfaces of the rotors 10 and 20 and the casing 30. The friction torque T is expressed by the following formula T, where S is the sliding area, l is the distance from the center of rotation to the sliding portion, and M is the frictional force per unit area acting between the rotors 10 and 20 and the casing 30. = M · S · l From this formula, as a means for reducing the friction torque T, the sliding portion located far from the center of rotation, that is, the casing 30 at the end surface of the outer rotor 20.
It is possible to reduce the sliding area between the and.

With this in mind, along the envelope drawn by the group of generating circles whose center is located on the trochoidal curve created in the range of the following equation n · R / (π · D)> 0.25: FIG. 3 shows an oil pump rotor including an inner rotor 10 having outer teeth 11 formed thereon. In this oil pump rotor, since the area of the end surface S _o of the inner teeth 21 is larger than the area of the end surface S _i of the outer teeth 11, the sliding area of the outer rotor 20 is also large, and as a result, the friction torque T Will increase.
(In Fig. 3, when n · R / (π · D) = 0.36)

Further, the external teeth 11 are formed along the envelope drawn by the generating circle group whose center is located on the trochoidal curve created in the range of the following expression n · R / (π · D) <0.15. FIG. 4 shows an oil pump rotor provided with the inner rotor 10 thus prepared. In this oil pump rotor, since the area of the end surface S _o of the inner teeth 21 is smaller than the area of the end surface S _i of the outer teeth 11, the sliding area of the outer rotor 20 is also small, and as a result, the friction torque T Decreases. However, the internal teeth 21 along the rotation direction of the outer rotor 20
Since the width W of the inner tooth 21 is narrowed, the inner tooth 21 is likely to be chipped due to the meshing with the outer tooth 11, and the durability of the inner tooth 21 is reduced. (In FIG. 4, n · R / (π · D) = 0.1
45)

When the value of nR / (πD) is arbitrarily selected, the value is adopted and the mechanical efficiency of the oil pump including the inner rotor 10 having the outer teeth 11 is shown in FIG. First, it can be seen that in the range of n · R / (π · D)> 0.25, the larger the value of n · R / (π · D), the lower the mechanical efficiency of the oil pump. It can be seen that in the range of 0.15 ≦ n · R / (π · D) ≦ 0.25, the smaller the value of n · R / (π · D), the higher the mechanical efficiency of the oil pump. In the range of n · R / (π · D) <0.15, the mechanical efficiency of the oil pump is not significantly improved, and the smaller the value of n · R / (π · D) is, the more it is as shown in FIG. In addition, the width W of the inner teeth 21 along the rotation direction of the outer rotor 20 is narrowed, and the inner teeth 21 are easily damaged.

FIG. 6 shows an oil pump rotor used in the oil pump corresponding to each point on the graph of FIG. The oil pump rotors used in the oil pump corresponding to points I, II, and III on the graph are respectively shown in FIG.
(I), FIG. 6 (II), and FIG. 6 (III). The oil pump rotors used in the oil pump corresponding to points IV, V, and VI on the graph are those shown in FIGS. 1, 3, and 4, respectively.

Further, a point VII which is a boundary on the graph
FIG. 7 shows an oil pump rotor used for the oil pump corresponding to. The oil pump rotor shown in FIG.
The inner rotor 10 is formed along the envelope drawn by a group of creation circles whose center is located on a trochoid curve created by satisfying n · R / (π · D) = 0.25. . In this oil pump rotor, the area of the end surface S _o of the inner tooth 21 is configured to be slightly larger than the area of the end surface S _i of the outer tooth 11, and the durability of the outer rotor 20 is emphasized. It can be said to be a thing. Internal tooth 21 than this
If the area of the end surface S _o of is increased, the mechanical loss due to the sliding resistance increases and the mechanical efficiency cannot be sufficiently improved.

From the above, the oil pump rotor shown in FIG. 1 is created in a range in which the outer teeth 11 of the inner rotor 10 satisfy the following equation: 0.15 ≦ n · R / (π · D) ≦ 0.25. It is formed along the envelope drawn by the generation circle group whose center is located on the trochoidal curve that has been formed. The shape of the inner rotor 10 determines the shape of the outer rotor 20, and the inner teeth 21 of the outer rotor 20 are damaged. The area of the end surface S _o is reduced to such an extent that it is not easy, and as a result, the sliding area of the entire outer rotor 20 is reduced and the drive torque T is reduced, so that the durability of the inner teeth 21 is ensured while the outer teeth are secured. The mechanical loss due to the sliding resistance generated between the rotor 20 and the casing 30 can be reduced. Therefore, it is possible to improve mechanical efficiency while ensuring durability and reliability as an oil pump.

A second embodiment of the oil pump rotor according to the present invention will be described with reference to the drawings. The components already described are given the same reference numerals and the description thereof will be omitted. This oil pump rotor has outer teeth 1 of the inner rotor 10.
1 is a drawing of a group of generating circles whose center is located on a trochoid curve created in a range satisfying the formula 0.15 ≦ n · R / (π · D) ≦ 0.25 shown in the first embodiment. A relief portion 40 formed along the envelope and having no contact with the inner teeth 21 of the outer rotor 20 on the front side and the rear side in the rotation direction of each outer tooth 11.
Is formed.

FIG. 8 shows how the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 mesh with each other. When the tips of the outer teeth 11 of the inner rotor 10 mesh with the tooth spaces of the inner teeth 21 to rotate the outer rotor 20, the line indicating the direction of the force of the outer teeth 11 pushing the inner teeth 21 is called the action line. Indicated by l. The outer teeth 11 and the inner teeth 21 are meshed with each other along the line of action l. The points on the tooth surface of the outer tooth 11 forming the intersection K _{s at} which meshing starts and the intersection K _{e at} which meshing ends are always constant, and these points are referred to as meshing start point k _s and end point k _e of the outer tooth 11. I reckon. Looking at one external tooth 11, the meshing start point k
_s is formed on the rear side in the rotational direction, and the meshing end point k _e is formed on the front side in the rotational direction.

Next, FIG. 9 shows a state of contact between the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 when the volume of the cell C becomes maximum. The volume of the cell C becomes maximum when the tooth space between the outer teeth 11 and the tooth space between the inner teeth 21 face each other. At this time, the tip of the external tooth 11 and the tip of the internal tooth 21 located in front of the cell C _max have a contact point P _{1 with each other.}
And the tips of the external teeth 11 located behind the cell C _max are in contact with each other at a contact point P ₂ . The points on the tooth surface of the outer tooth 11 forming the contacts P ₁ and P ₂ that maximize the volume of the cell C are always constant, and these points are the front contact point p ₁ and the rear contact point p _{2 of the} outer tooth 11. To consider. Regarding one external tooth 11, the front contact point p ₁ is formed on the rear side in the rotation direction, and the rear contact point p ₂ is formed on the front side in the rotation direction.

The relief portion 40 has a meshing end point k _e and a rear contact point p ₂ located on the front side in the rotational direction with respect to one outer tooth 11.
And the tooth flank between the meshing start point k _s located on the rear side in the rotation direction and the front contact point p ₁ are cut off, and the tooth flank of the external tooth 11 between them is formed. It has no contact with the internal teeth 21.

With respect to the oil pump rotor constructed as described above, the increase and decrease in the volume of the cell C in one cycle and the state of contact between the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 are shown below. .

First, in the process of meshing the outer teeth 11 and the inner teeth 21, the outer teeth 11 mesh with the inner teeth 21 to rotate the outer rotor 20, as in the conventional case.

When the outer teeth 11 and the inner teeth 21 have finished meshing with each other,
When the process of increasing the volume of the cell C along the suction port 31 is performed, the relief portion 40 is provided on the front side in the rotation direction of the outer teeth 11 of the inner rotor 10 that were conventionally in contact with the inner teeth of the outer rotor.
The outer teeth 1 before and after the cell C due to the provision of
1 and the internal teeth 21 are no longer in contact with each other.

When the front of the cell C passes through the suction port 31, first, the tips of the external teeth 11 and the tips of the internal teeth 21 located in front of the cell C come into contact with each other. Then, when the rear side of the cell C passes through the suction port 31, the external teeth 11 located behind the cell C are
The tip of the tooth and the tip of the inner tooth 21 are in contact with each other, and a cell C _max having the maximum volume is formed between the suction port 31 and the discharge port 32. The tooth tips of the external teeth 11 and the internal teeth 21 located behind the cell C
The contact with the tooth tip of is maintained until the contact point reaches the discharge port 31.

In the process of decreasing the volume of the cell C along the discharge port 31, the relief portion 40 is formed on the rear side in the rotation direction of the outer tooth 11 of the inner rotor 10 which was in contact with the inner tooth 21 of the outer rotor 20. Since it is provided, the outer teeth 11 and the inner teeth 21 do not come into contact with each other.

By the way, the volume of the cell C is equal to the suction port 31.
In the process of increasing along with the discharge port 32, and in the process of increasing the volume of the cell C along the discharge port 32, the adjacent cells C are brought into communication by providing the escape portion 40. Cell C is intake port 3
1, or because it is located along the discharge port 32 and is in a communication state from the beginning, this does not cause a reduction in the transfer efficiency of the oil pump.

As a result, the process of engagement between the outer teeth 11 and the inner teeth 21 and the volume of the cell C becomes maximum, so that the suction port 3
The external teeth 11 and the internal teeth 21 contact each other only in the process of moving from the 1st side to the discharge port 32 side, and the process in which the volume of the cell C increases along the suction port 31 and the volume of the cell C changes to the discharge port 32. In the process of decreasing along, the outer teeth 11 and the inner teeth 21 do not come into contact with each other, and the number of sliding contact points between the inner rotor 10 and the outer rotor 20 decreases, so that the sliding resistance generated between the tooth surfaces decreases.

From these facts, this oil pump rotor has a trochoidal curve created in a range in which the outer teeth 11 of the inner rotor 10 satisfy the following equation: 0.15 ≦ n · R / (π · D) ≦ 0.25. An escape portion 40 which is formed along the envelope drawn by the generation circle group whose center is located above and which does not have contact with the internal teeth 21 of the outer rotor 20 on the front side and the rear side in the rotation direction of each external tooth 11. In addition to the effect described in the first embodiment, the meshing process of the outer teeth 11 and the inner teeth 21 and the volume of the cell C are maximized so that the suction port 31 side can discharge the discharge port 31 from the discharge port 31 side. The external teeth 11 only in the process of moving to the 32 side
And the inner teeth 21 come into contact with each other, and the volume of the cell C is reduced to the suction port 31.
And the volume of the cell C increases along the discharge port 3
In the process of decreasing along with 2, external teeth 11 and internal teeth 21
The inner rotor 10 and the outer rotor 2 do not come into contact with each other.
Since the number of sliding contact points with 0 is reduced and the sliding resistance generated between the tooth surfaces is reduced, the drive torque required to drive the oil pump can be reduced and the mechanical efficiency of the oil pump can be improved. Further, by providing the escape portion 40 on the rear side in the rotation direction of the outer teeth 11, the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 which are generated by the vibration of the oil pump when the oil pump is actually used. It is possible to prevent interference with and reduce mechanical loss.

In this embodiment, the inner rotor 10 is constructed by providing the relief portions 40 on the front side and the rear side of the outer teeth 11 in the rotation direction, but the relief portions 40 are formed only on the front side of the outer teeth 11 in the rotation direction. It may be provided.

[0037]

As described above, in the oil pump rotor of the present invention, the outer teeth of the inner rotor have a tip circle diameter of the inner rotor and a creation circle radius of D (m), respectively.
m) and R (mm), the generation circle group whose center is located on the trochoid curve created in the range satisfying the following formula 0.15 ≦ n · R / (π · D) ≦ 0.25 It is formed along the drawn envelope, the shape of the outer rotor is determined by the shape of this inner rotor, and the area of the end face is reduced to the extent that the inner teeth of the outer rotor are not easily damaged,
As a result, the sliding area of the entire outer rotor is reduced and the drive torque is reduced, so that mechanical loss due to sliding resistance generated between the outer rotor and the casing is reduced while ensuring the durability of the internal teeth. . Therefore,
It is possible to improve mechanical efficiency while ensuring durability and reliability as an oil pump.

Furthermore, in the oil pump rotor of the present invention, since the outer rotor of the inner rotor is provided with the relief portion on the front side in the rotational direction, or in addition to this, the relief portion is provided on the rear side in the rotational direction,
Only when the outer teeth and the inner teeth mesh with each other and when the cell volume becomes maximum and moves from the suction port side to the discharge port side, the outer teeth and the inner teeth come into contact with each other, and the cell volume becomes the suction port. During the process of increasing along the discharge port and the process of decreasing the cell volume along the discharge port, the outer and inner teeth do not come into contact with each other, and the sliding contact points between the inner rotor and the outer rotor decrease, causing a gap between the tooth surfaces. Since the sliding resistance is reduced, the drive torque required to drive the oil pump can be reduced and the mechanical efficiency of the oil pump can be improved. In addition, by providing a relief portion on the rear side of the external teeth in the rotation direction, interference between the external teeth and internal teeth that occurs when the oil pump vibrates when the oil pump is actually used is reduced, reducing mechanical loss. can do.

[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 the outer teeth of the inner rotor have the following formula: 0.15 ≦ n · R / (π · D) ≦ 0.25 FIG. 6 is a plan view showing an oil pump rotor formed along an envelope drawn by a generation circle group whose center is located on a trochoid curve generated in a range satisfying the above condition.

FIG. 2 is a plan view showing a procedure for creating the inner rotor shown in FIG.

FIG. 3 is a diagram to be compared with the oil pump rotor shown in FIG. 1, in which the outer teeth of the inner rotor are created in a range satisfying the following expression n · R / (π · D)> 0.25. It is a top view which shows the oil pump rotor formed along the envelope which the creation circle group which centered on the trochoid curve draws.

FIG. 4 is a view to be compared with the oil pump rotor shown in FIG. 1, in which the outer teeth of the inner rotor are created in a range satisfying the following expression n · R / (π · D) <0.15. It is a top view which shows the oil pump rotor formed along the envelope which the creation circle group which centered on the trochoid curve draws.

FIG. 5 is a graph showing mechanical efficiency of an oil pump including an inner rotor having outer teeth formed by arbitrarily selecting a value of n · R / (π · D).

6 is a graph of I, II, and III shown in FIG.
3 is a plan view showing an oil pump rotor used in the oil pump corresponding to each point of FIG.

7 is a plan view showing an oil pump rotor used in the oil pump corresponding to a point VII on the graph shown in FIG.

FIG. 8 is a view showing a second embodiment of the oil pump rotor according to the present invention, and is a plan view of relevant parts showing a state where the outer teeth of the inner rotor and the inner teeth of the outer rotor are meshed with each other.

FIG. 9 is likewise a plan view of relevant parts showing the state of contact between the outer teeth of the inner rotor and the inner teeth of the outer rotor when the cell volume is maximized.

[Explanation of symbols]

 10 Inner rotor 11 Outer tooth 20 Outer rotor 21 Inner tooth 30 Casing 31 Suction port 32 Discharge port P Tip circle Q Q Generating circle e Eccentric amount D Tip circle diameter R Generating circle radius t Trochoid curve h Envelope

Claims (3)

[Claims] 1. An inner rotor having n (n is a natural number) outer teeth formed, an outer rotor having n + 1 inner teeth formed to mesh with the outer teeth, an intake port for sucking fluid, and a fluid. When the rotors mesh with each other and rotate, the fluid is transferred by sucking and discharging the fluid due to the volume change of the cells formed between the tooth surfaces of the rotors. In the oil pump rotor used for the oil pump, when the outer teeth of the inner rotor are the tip circle diameter and the creation circle radius of the inner rotor are D (mm) and R (mm), respectively, the following formula 0.15 ≦ It is characterized in that it is formed along the envelope drawn by the group of creation circles whose center is located on the trochoidal curve created in the range satisfying n · R / (π · D) ≦ 0.25. Oil pump rotor that. 2. The oil pump rotor according to claim 1, wherein an escape portion that does not come into contact with the inner teeth of the outer rotor is provided on the front side in the rotation direction of the outer teeth of the inner rotor. Characteristic oil pump rotor. 3. The oil pump rotor according to claim 2, wherein the relief portion is provided on the rear side in the rotation direction of the outer teeth of the inner rotor.