JP2005120850A - Internal gear pump rotor and internal gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal gear pump rotor and an internal gear pump, surely reducing the driving torque. <P>SOLUTION: This internal gear pump rotor includes: an inner rotor 10 provided with n-number (n is a natural) of external teeth; and an outer rotor 20 provided with (n+1)-number of internal teeth meshing with the external teeth. When both rotors 10, 20 mesh with each other and rotate, a fluid is sucked and discharged by a change in volume of cells S formed between the tooth flanks of both rotors 10, 20 to carry the fluid. The internal tooth is provided with a missing correction part 40 not coming into contact with the external tooth. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an internal gear pump rotor and an internal gear pump for sucking and discharging fluid by changing the volume of a cell formed between an inner rotor and an outer rotor.

2. Description of the Related Art Conventionally, a small internal gear type internal gear pump having a simple structure has been widely used as a lubricating oil pump, a fuel pump, or the like of an automobile.
Such an internal gear pump has 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 fluid is sucked. A suction port and a casing formed with a discharge port through which fluid is discharged. A plurality of grooves formed between the two rotors by rotating the inner rotor to rotate the outer rotor with the outer teeth meshing with the inner teeth. The fluid is sucked and discharged by changing the volume of the cell.

  The cells are individually partitioned by contacting 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 rotational direction, respectively. Each cell has a minimum volume during the process of meshing between the external teeth and the internal teeth, and when moving along the suction port, the volume is increased to suck the fluid. Then, after the volume reaches the maximum, when moving along the discharge port, the volume is decreased and the fluid is discharged.

  By the way, in such an inscribed gear pump rotor, the end surfaces of both rotors and the casing, the outer periphery of the outer rotor and the casing are always in sliding contact, and the outer teeth of the inner rotor and the inner teeth of the outer rotor However, a large driving torque is required to drive the inscribed gear pump rotor against these sliding resistances.

As a means for solving such a problem, a missing correction portion that does not contact the inner teeth of the outer rotor is formed on the outer teeth of the inner rotor, and the outer teeth of the inner rotor are used as outer missing teeth. A configuration formed between a meshing point when meshing with the inner teeth of the rotor and a contact point between the outer teeth of the inner rotor and the inner teeth of the outer rotor when the volume of the cell is maximized is disclosed (for example, Patent Document 1).
Japanese Patent Laid-Open No. 9-166091

  However, such an inscribed gear pump rotor has not yet been able to effectively reduce the driving force of the inscribed gear pump rotor.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an inscribed gear pump rotor and an inscribed gear pump that can reliably reduce driving torque.

In order to achieve the above object, the present invention proposes the following means.
The invention according to claim 1 includes an inner rotor in which n (n is a natural number) external teeth are formed, and an outer rotor in which (n + 1) internal teeth that mesh with the external teeth are formed. An internal gear pump rotor that conveys fluid by sucking and discharging fluid by a volume change of a cell formed between tooth surfaces of both rotors when the rotor is meshed and rotated, and the outer teeth of the inner rotor Is a shape based on an abduction cycloid curve created by an abduction circle that circumscribes the first basic circle and rolls without slipping, and the tooth shape of the tooth gap is The inner tooth of the outer rotor has a tooth profile at the tip of the second base circle, and the inner tooth of the outer rotor has a shape based on an inversion cycloid curve created by an inversion circle inscribed in the base circle of 1 and rolling without slipping. Slip inscribed The shape is based on the adductor cycloid curve created by the rolling adductor circle, and the tooth profile of the tooth gap is formed by the abduction circle that circumscribes the second basic circle and rolls without slipping. It is a shape based on a rotating cycloid curve, and at least on the rear side in the rotational direction of the inner teeth of the outer rotor, a missing correction part that lacks a meat part that forms the inner teeth on the basis of the cycloid curve, The following formula,
0.1 ≦ b / (a + b) ≦ 0.5
And −0.2 ≦ c / d ≦ 0.2
However,
a: Distance in the normal direction between the end of the missing tooth correction portion on the tooth tip side of the internal tooth and the second basic circle b: The end of the missing correction portion on the tooth tip side of the internal tooth, and the internal tooth Distance c in the normal direction to the top of the tooth tip of the tooth d: distance in the normal direction between the end of the missing correction portion on the tooth gap side of the internal tooth and the second basic circle d: the second basic circle It is formed in the part which satisfy | fills the distance of the normal line direction with the tooth gap bottom part of a tooth | gear.

  According to the inscribed gear pump rotor according to the present invention, since the missing correction portion is formed only in the range indicated by the above formula among the inner teeth of the outer rotor, the outer teeth of the inner rotor are the outer rotor. The inner rotor and outer rotor can be brought into contact with each other in the process of meshing with the inner teeth and the process of moving the maximum volume cell from the suction port side to the discharge port side, and the cell increases along the suction port. In the process of decreasing along the discharge port, the inner rotor and the outer rotor can be prevented from contacting each other.

  Accordingly, it is possible to reduce the meshing resistance between the inner teeth of the outer rotor and the outer teeth of the inner rotor, and even in such a configuration, either the lowering of the fluid conveyance efficiency or either one of the two rotors can be achieved. It is possible to suppress a decrease in mechanical efficiency in which the rotational driving force is transmitted to the other, and to effectively reduce the driving force of the inscribed gear pump rotor.

  Further, when the missing correction portion is formed so as to reach the end in the tooth width direction of the outer rotor, the sliding contact portion between the casing in which the two rotors are housed and the outer rotor is also reduced. In this case, since the number of inner teeth of the outer rotor is greater than the number of outer teeth of the inner rotor, when the missing correction part is formed on all teeth, than when the missing correction part is formed on the inner rotor, When the outer rotor is formed, the amount of decrease in the sliding contact portion with the casing is larger.

  The invention according to claim 2 is the inscribed gear pump rotor according to claim 1, wherein at least a front side in the rotational direction of the outer teeth of the inner rotor is provided with a meat portion that forms the outer teeth on the basis of the cycloid curve. When the bulge correcting portion bulged outwardly meshes with the outer teeth and the inner teeth of the outer rotor, the surface along the surface shape of the missing correcting portion when the volume of the cell is minimized It is characterized by being formed into a shape.

  According to the inscribed gear pump rotor according to the present invention, since the bulging correction portion is formed on the external tooth, the interval between the bulging correction portion and the external tooth can be reduced, and the bulging correction is performed. It is possible to prevent the fluid from flowing back between the part and the external tooth. Therefore, in combination with the reduction of the sliding contact portion described above, not only the mechanical efficiency but also the pump efficiency can be improved.

  The invention according to claim 3 is the inscribed gear pump rotor according to claim 1 or 2, wherein at least one of the inner rotor and the outer rotor is made of a synthetic resin having viscoelastic characteristics. .

  Since the inscribed gear pump rotor according to the present invention is made of synthetic resin having viscoelastic characteristics, noise during driving of the inscribed gear pump rotor can be reduced. In particular, when a polyphenylene sulfide resin or a polyether ether ketone resin is used as the synthetic resin, it is possible to reliably withstand loads acting on these rotors when the inscribed gear pump rotor is driven. Further, since these are thermoplastic resins, they can be injection-molded, and low-cost and high-precision production can be realized.

  According to a fourth aspect of the present invention, there is provided an internal gear pump rotor according to any one of the first to third aspects, a casing in which a suction port for sucking fluid and a discharge port for discharging fluid are formed, and the inner And a direct current motor that rotationally drives the rotor, and is configured to convey the fuel by sucking and discharging the fuel used in an internal combustion engine or the like by the volume change of the cell formed between the tooth surfaces of the rotors. It is characterized by that.

  According to the internal gear pump according to the present invention, the sliding of the outer rotor is also achieved in the internal gear pump that transports a fuel such as light oil having a relatively high viscosity by driving a DC motor having a relatively small driving force. Since the resistance is reduced, it is driven well.

  According to the internal gear pump rotor and the internal gear pump according to the present invention, it is possible to reduce the meshing resistance between the inner teeth of the outer rotor and the outer teeth of the inner rotor. It is possible to suppress a decrease in fluid conveyance efficiency and a decrease in mechanical efficiency in which the rotational driving force of one of the rotors is transmitted to the other, effectively reducing the driving force of the internal gear pump rotor. Can be planned.

Hereinafter, an embodiment of an inscribed gear pump rotor and an inscribed gear pump according to the present invention will be described with reference to FIGS. 1 to 6.
The inscribed gear pump rotor shown in FIG. 1 includes an inner rotor 10 in which n (n is a natural number) external teeth 11 are formed, and an outer in which (n + 1) internal teeth 21 that mesh with the external teeth 11 are formed. The internal gear pump is housed inside the casing 30.

The inner rotor 10 includes n (9 in the present embodiment) external teeth 11 and is attached to a DC motor via a rotating shaft (not shown) and is surrounded around the axis O ₁ in the casing 30. It is supported so that it can rotate in the direction.
The outer rotor 20 is provided with n + 1 (10 in this embodiment) internal teeth 21, the eccentric the axis _{O 2} with respect to the axis _{O 1} of the inner rotor 10 (eccentricity: e) is not the inner Teeth 21 are arranged in meshed with the external teeth 11, it is rotatably supported in the circumferential direction at inside of the casing 30 about the axis O _2.

  Both the rotors 10 and 20 are made of a synthetic resin having viscoelastic properties. It is preferably made of a thermoplastic resin, more preferably a polyphenylene sulfide resin or a polyether ether ketone resin. This material is appropriately selected according to various loads such as driving torque and temperature acting on the rotors 10 and 20, the use environment, and the like.

  The casing 30 is formed with an arc-shaped suction port (not shown) along the cell S whose volume is increasing among the cells S formed between the tooth surfaces of the rotors 10 and 20. An arc-shaped discharge port (not shown) is formed along the cell S whose volume is decreasing.

Here, the external teeth 11 of the inner rotor 10 are based on the abduction cycloid curve created by the first abduction circle Ai in which the tooth profile of the tooth tip portion 11a circumscribes the first basic circle Di and rolls without slipping. And the tooth profile of the tooth gap portion 11b is based on the inversion cycloid curve created by the first inversion circle Bi inscribed in the first basic circle Di and rolling without slipping. ing.
The inner teeth 21 of the outer rotor 20 are based on an addendum cycloid curve created by a second addendum circle Bo in which the tooth profile of the tooth tip portion 21a is inscribed in the second basic circle Do and rolls without slipping. And the tooth profile of the tooth gap 21b is based on the abduction cycloid curve created by the second abduction circle Ao circumscribing the second base circle Do and rolling without slipping. Yes.

On the rear side and the front side in the rotation direction of the inner teeth 21 of the outer rotor 20, a missing correction part 40 is formed by missing the meat part forming the inner teeth with reference to the cycloid curve. The outer teeth 11 of the inner rotor 10 are not in contact with each other.
Further, on the rear side and the front side in the rotation direction of the outer teeth 11 of the inner rotor 10, bulge correction portions 50 are formed by bulging outward the meat portions forming the outer teeth 11 with reference to the cycloid curve. Then, the surface shape of the bulge correcting portion 50 is such that it follows the surface shape of the missing correcting portion 40 when the outer teeth 11 and the inner teeth 21 of the outer rotor 20 mesh with each other and the volume of the cell S is minimized. It is a simple shape.
In the present embodiment, the missing correction part 40 is formed on all the inner teeth 21, the bulging correction part 50 is formed on all the outer teeth 11, and the missing correction part 40 and the bulging correction part 50 are Both are formed in a planar shape as shown in FIGS.

As shown in FIG. 2, the missing correction portion 40 is an end portion 40a on the tooth tip portion 21a side of the tooth surfaces on the rear side and the front side in the rotation direction of the internal teeth 21 (hereinafter simply referred to as “tooth tip side end portion 40a”. ”) And an end 40b on the tooth groove 21b side (hereinafter simply referred to as“ tooth groove side end 40b ”).
Each of these end portions 40a and 40b is located on the tooth surface of the internal tooth 21 at a portion represented by the following formula. That is, in FIG. 2, the distance in the normal direction between the second basic circle Do and the tip portion side end portion 40a is a, the tip top portion 21c of the internal tooth 21, the tip portion side end portion 40a, Where b is the distance in the normal direction of
0.1 ≦ b / (a + b) ≦ 0.5
The tooth tip side end 40a is located at a portion satisfying the condition, and in FIG. 2, the distance between the second basic circle Do and the tooth gap side end 40b is c, and the tooth gap bottom 21d of the internal tooth 21 And the distance from the second basic circle Do as d,
−0.2 ≦ c / d ≦ 0.2
The tooth gap part side edge part 40b is located in the part which satisfy | fills. In addition, regarding the distance c, when the tooth gap portion side end portion 40b is positioned on the tooth groove portion 21b side from the second basic circle Do (see FIG. 2), it is positive (+), and the tooth groove portion side end portion 40b is the first portion. The case where it is located on the tooth tip 21a side of the second basic circle Do is shown as negative (-).

The tooth tip part side end 40a and the tooth gap part side end part 40b are positioned in a portion satisfying the above expression in the tooth surface on the rear side and the front side in the rotation direction of the internal tooth 21, and the missing correction part is within a range satisfying this expression. When 40 is formed, the missing correction part 40 is used when the inner tooth 21 of the outer rotor 20 engages with the outer tooth 11 of the inner rotor 10 and the volume of the cell S is maximized. It is formed between the contact point with the outer teeth 11 of the other.
The bulge correcting portion 50 is formed at a position facing the missing correcting portion 40 when the volume of the cell S is the smallest among the outer teeth 11 of the inner rotor 10, and the tooth surface of the outer teeth 11 and the missing correcting portion. It is formed so as to fill the interval with 40. Further, when the volume of the cell S is minimized, as described above, the surface of the bulge correcting portion 40 and the surface of the missing correcting portion 40 are substantially parallel, and the gap correcting portion 40 and the bulging correcting portion 50 are The distance is substantially constant in these formation regions.

Here, FIG. 3 shows a contact state 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 S is minimized.
The volume of the cell S is minimized when the tooth tip of the external tooth 11 and the tooth gap between the internal teeth 21 face each other.
In this figure, when the inner rotor 10 rotates about the axis O ₁ , the external teeth 11 come into contact with the internal teeth 21 of the outer rotor 20, and the tooth tips of the external teeth 11 become tooth gaps of the internal teeth 21. A point on the tooth surface of the outer tooth 11 and the inner tooth 21 that forms a point (meshing start point) k ₁ , and the outer tooth 11 starts to move away from the inner tooth 21 and a point at which the meshing ends (meshing end point) k ₂ is formed. For each, it is always constant. Looking at the one of the internal teeth 21, the start point k ₁ meshing is formed after the rotating direction side, meshing end point k ₂ is formed in the rotation direction front side. Also, looking at the one of the external teeth 11, the start point k ₁ meshing is formed in the rotation direction front side, the meshing end point k ₂ is formed after the rotating direction side.

FIG. 4 shows a contact state 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 S is maximized.
The volume of the cell S is maximized when the tooth gap between the external teeth 11 and the tooth gap between the internal teeth 21 face each other. At this time, the tooth tip of the external tooth 11 located in front of the cell S _{max in} the rotation direction and the tooth tip of the internal tooth 21 are in contact at the contact point P ₁ and the external tooth located behind the rotation direction of the cell S _max. 11 and tooth tips of the tooth tips and the inner teeth 21 of the contacts at the contact point P _2. The points on the tooth surface of the inner teeth 21 that form the contact points P ₁ and P ₂ where the volume of the cell S is maximum are always constant, and these points are the front contact point p ₁ and the rear contact point of the inner teeth 21. regarded as p _2. Looking at the one of the internal teeth 21, front contact point p ₁ is formed in the rotation direction front side, the rear contact point p ₂ is formed after the rotating direction side.

Missing correction unit 40, as shown in FIG. 5, after the end point k ₂ meshing positioned in the rotation direction front tooth surface between the front contact point p _1, and a start point k ₁ meshing positioned in the rotational direction of the rear side the tooth surfaces between the contact point p _2, based on the above-mentioned cycloid (see the two-dot chain lines in FIG. 5) is formed in a state of being cut up to 0.01mm above 1.00mm rotating direction The tooth surface of the inner tooth 21 in this portion has no contact with the outer tooth 21. That is, the missing correction part 40 is continuously formed over the entire region of the inner teeth 21 in the tooth width direction.

Here, when the formula b / (a + b) is smaller than 0.1, the tooth tip portion side end portion 40a of the missing correction portion 40 is moved to the tooth tip portion 21a from the arrangement position of the contact points p ₁ and p ₂ . Since it will be located on the top portion 21c side, the liquid tightness of the cell _{Smax with} the maximum volume cannot be maintained, leading to a decrease in fluid transfer efficiency. When this equation is larger than 0.5, It is not possible to satisfactorily reduce the meshing resistance between the external teeth 11 and the internal teeth 21. Therefore, the formula b / (a + b) is set to 0.1 or more and 0.5 or less.

Further, when the expression c / d is smaller than −0.2, the meshing resistance between the outer teeth 11 and the inner teeth 21 cannot be reduced satisfactorily. Since the tooth groove part side end part 40b of the part 40 is located on the bottom part 21d side of the tooth groove part 21b from the arrangement position of the meshing points k ₁ and k ₂ , the internal teeth 21 and the external teeth 11 are good. Engagement cannot be realized, leading to a reduction in transmission efficiency of the rotational driving force from the inner rotor 10 to the outer rotor 20. Therefore, the formula c / d is set to be not less than −0.2 and not more than 0.2.

  As described above, the bulge correcting portion 50 is formed at a position facing the missing correcting portion 40 when the volume of the cell S is minimized among the outer teeth 11 of the inner rotor 10. In a non-contact state, the gap between the tooth surface of the external tooth 11 and the missing correction portion 40 is filled. That is, the shape of the outer surface of the bulging correction portion 50 that faces the missing correction portion 40 is the same shape as the shape of the outer surface of the missing correction portion 40 that faces the bulging correction portion 50. When the volume of the cell S is minimized, the missing correction portion 40 and the bulging correction portion 50 are shaped so that the tangents of the surfaces facing each other are substantially parallel.

  About the internal gear pump rotor comprised as mentioned above, the increase / decrease in the capacity | capacitance in 1 cycle of the cell S and the contact state of the external tooth 11 of the inner rotor 10 and the internal tooth 21 of the outer rotor 20 are shown below.

First, in the process of meshing between the external teeth 11 and the internal teeth 21, the outer teeth of the external teeth 11 mesh with the tooth grooves of the internal teeth 21 and rotate the outer rotor 20, as in the past.
When the engagement between the outer teeth 11 and the inner teeth 21 is finished and the process proceeds to a process in which the volume of the cell S increases along the suction port, the outer rotor 20 that has been in contact with the outer teeth 21 of the inner rotor 20 in the related art. Since the missing correction part 40 is provided on the rear side in the rotation direction of the inner teeth 21, contact between the outer teeth 11 and the inner teeth 21 before and after the cell S is avoided.

When the front of the cell S in the rotation direction passes through the suction port, first, the tooth tip of the external tooth 11 located in front of the cell S in the rotation direction contacts the tooth tip of the internal tooth 21 (the front contact point p ₁ shown in FIG. 4). ). Subsequently, when the rotational direction rearward of the cell S passes through the suction port, the tooth tip of the external tooth 11 and the tooth tip of the internal tooth 21 located behind the rotational direction of the cell S are in contact with each other (the rear contact point p shown in FIG. 4). ₂ ) A cell S _max having a maximum volume is formed between the suction port and the discharge port. Contact between the tooth tip of the external tooth 11 and the tooth tip of the internal tooth 21 located behind the cell S in the rotation direction is maintained until the contact point reaches the discharge port.

  When the process proceeds to a process in which the volume of the cell S decreases along the discharge port, the missing correction portion 40 is provided on the front side in the rotation direction of the inner teeth 21 of the outer rotor 20 that have been in contact with the outer teeth 11 of the inner rotor 10 in the related art. Therefore, contact between the external teeth 11 and the internal teeth 21 is avoided.

  As a result, the external teeth 11 and the internal teeth 21 come into contact only in the process in which the external teeth 11 and the internal teeth 21 mesh with each other and in the process in which the volume of the cell S is maximized and moves from the suction port side to the discharge port side. In the process in which the volume of the cell S increases along the suction port and the process in which the volume of the cell S decreases along the discharge port, contact between the external teeth 11 and the internal teeth 21 is avoided. The number of sliding contact points between the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 is reduced, and the sliding resistance generated between these tooth surfaces is reduced.

Further, since the bulge correcting portion 50 is formed on the outer teeth 11, the distance between the outer teeth 11 and the inner teeth 21 is the minimum necessary so as not to inhibit the rotation of the inner rotor 10 in all the above processes. To be kept. Therefore, the occurrence of fluid backflow or the like can be suppressed, and the fluid conveyance efficiency can be maintained at or above the conventional level.
Furthermore, since the missing correction portion 40 is formed on the inner teeth 21 so as to reach the end of the outer rotor 20 in the tooth width direction, the outer rotor 20 and the casing 30 in the portion where the missing correction portion 40 is formed. Is avoided, and the sliding resistance generated between these portions 20 and 30 is also reduced.

  According to the inscribed gear pump rotor and the inscribed gear pump described in the present embodiment, the process of meshing between the outer teeth 11 and the inner teeth 21 and the volume of the cell S are maximized from the suction port side. Only in the process of moving to the discharge port side, the external teeth 11 and the internal teeth 21 come into contact with each other, the process of increasing the volume of the cell S along the suction port, and the volume of the cell S decreasing along the discharge port. In the process, the outer teeth 11 and the inner teeth 21 do not come into contact with each other, so the number of sliding contact points between the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 is reduced, and the sliding resistance generated between these tooth surfaces is reduced. Get smaller. Therefore, it is possible to reduce the driving torque necessary for driving the inscribed gear pump rotor and improve the mechanical efficiency of the inscribed gear pump rotor.

  Further, since both the rotors 10 and 20 are made of a synthetic resin having viscoelastic characteristics, it is possible to reduce noise when driving the inscribed gear pump rotor. In particular, when a polyphenylene sulfide resin or a polyether ether ketone resin is used as the synthetic resin, it is possible to reliably withstand the load acting on both the rotors 10 and 20 when the inscribed gear pump rotor is driven. Further, since these are thermoplastic resins, they can be injection-molded, and low-cost and high-precision production can be realized.

  As described above, the mechanical efficiency and the conveyance efficiency can be improved as described above even in the internal gear pump that conveys a fuel such as a light oil having a relatively high viscosity by driving a DC motor having a relatively small driving force. Therefore, the inscribed gear pump can be driven satisfactorily.

  By the way, in the process in which the volume of the cell S increases along the suction port and the process in which the volume of the cell S decreases along the discharge port, the adjacent cells S are provided with the omission correction unit 40. The communication state is established. However, since each cell S is located along the suction port or the discharge port in both processes, it is originally in a communicating state, and this does not cause a decrease in the conveyance efficiency of the inscribed gear pump rotor. .

A verification test was conducted on the effect of the inscribed gear pump described above.
First, schematic configurations of examples and comparative examples according to the present invention will be described.
The outer diameter of the outer rotor 20 is 25 mm, the number of the inner teeth 21 is nine, the number of the outer teeth 11 of the inner rotor 10 is eight, and the tooth width of each of these teeth 21 and 11 is 6 mm. , 20 was accommodated in the casing 30 to form an inscribed gear pump. In this configuration, the eccentric amount e of both the rotors 10 and 20 is 0.985 mm, and the theoretical discharge amount is 0.57 cm ³ / rev. The discharge pressure was 250 kPa.

  In the internal gear pump configured as described above, the rotational speed, the discharge amount, and the current consumption value when 12V was loaded on the DC motor that rotationally drives the inner rotor 10 were measured. As an example, missing correction portions 40 are formed in all the inner teeth 21 of the outer rotor 20 in the entire width direction of the outer rotor 20, and bulge correction is corrected in all of the outer teeth 11 of the inner rotor 10 in the entire width direction of the teeth. The part 50 was formed, and the thing of the conventional structure which does not have the missing correction part 40 and the bulging correction part 50 was used as a comparative example.

  As a result, in the comparative example, the rotation speed was 4000 rpm, the discharge amount was 82 L / hour, and the current consumption value was 6 A. In the example, the rotation speed was 5200 rpm, the discharge amount was 107 L / hour, and the current consumption value was 4 A. It was. From the above, it was confirmed that by forming the missing correction portion 40 in the outer rotor 20, it is possible to reduce the power consumption of the inscribed gear pump rotor, that is, to improve the mechanical efficiency and the conveyance efficiency.

Next, 10 types of inscribed gear pump rotors with different values of the aforementioned formulas b / (a + b) and c / d were formed, and the conveyance efficiency and mechanical efficiency were measured for each pump having these types of gear pump rotors. did.
First, schematic configurations of examples and comparative examples according to the present invention will be described.
The outer diameter of the outer rotor is 27.5 mm, the number of inner teeth 21 is 13, the number of outer teeth of the inner rotor is 12, and the tooth width of each tooth is 7 mm. An inscribed gear pump was formed by housing the mold gear pump rotor in a casing.
In this configuration, the eccentric amount e of both rotors is 0.79 mm, and the theoretical discharge amount is 0.67 cm ³ / rev. The discharge pressure was 250 kPa.

Further, in this configuration, a pump having an internal gear pump rotor in which the formula b / (a + b) satisfies 0.1 or more and 0.5 or less and the formula c / d satisfies −0.2 or more and 0.2 or less is illustrated. Examples 1 to 5 shown in FIG. 8 are used, and pumps having pump rotors whose formulas do not satisfy this range are shown as Comparative Examples 1 to 5 shown in FIG.
As shown in FIG. 8, in Examples 1 to 5, the expression b / (a + b) satisfies 0.1 or more and 0.5 or less, and the expression c / d satisfies −0.2 or more and 0.2 or less. The gear pump having the contact type gear pump rotor has a conveyance efficiency of 72% or more and a mechanical efficiency of 30% or more, and it was confirmed that a high level of both the conveyance efficiency and the mechanical efficiency can be realized.

In the present embodiment, the configuration in which the missing correction part 40 is formed on all the inner teeth 21 and the bulging correction part 50 is formed on all the outer teeth 11 is shown. However, at least one tooth 21, 11 is shown. It only has to be formed.
Moreover, although the structure which formed the omission correction | amendment correction | amendment part 40 and the bulging correction | amendment part 50 over the whole tooth width direction of each tooth | gear 21 and 11 was employ | adopted, it should just be formed in at least one part in this direction.

  Furthermore, a direct current motor is adopted as the driving means for the inscribed gear pump rotor, and fuel such as light oil is adopted as the fluid handled by the inscribed gear pump. Instead, the driving means is applied to the crankshaft of the engine. A crankshaft directly connected drive in which the inner rotor is directly connected and driven by the rotation of the engine may be employed, and lubricating oil may be employed as the fluid.

Furthermore, in this embodiment, although the structure which formed the missing correction part 40 and the bulging correction part 50 in the planar shape was shown, you may form in a curved surface shape, as shown in FIG. In this case, when the volume of the cell S is minimized, the missing correction portion 40 is formed with the curvature radius R1, and the bulging correction portion 50 is formed with the same center X as the curvature radius R1 and with a curvature radius R2 larger than the radius R1. May be formed.
Further, the number of rolling circles forming the inner teeth 21 and the outer teeth 11 may be any.

  It is possible to reduce the meshing resistance between the inner teeth of the outer rotor and the outer teeth of the inner rotor, and even in such a configuration, the fluid conveyance efficiency is reduced and either one of the rotors is rotated. A reduction in mechanical efficiency in which the driving force is transmitted to the other can be suppressed, and the driving force of the inscribed gear pump rotor can be effectively reduced.

1 is a plan view showing an inscribed gear pump rotor according to an embodiment of the present invention. It is a principal part top view which shows the internal tooth of the outer rotor in the internal gear pump rotor shown in FIG. 1, Comprising: It is a top view which shows the formation position of the missing correction part on the basis of the 2nd basic circle. FIG. 2 is a plan view of a main part showing a state of meshing between outer teeth of an inner rotor and inner teeth of an outer rotor in the inscribed gear pump rotor shown in FIG. 1. FIG. 2 is a plan view of a principal part showing a contact state between outer teeth of an inner rotor and inner teeth of an outer rotor when the volume of a cell in the inscribed gear pump rotor shown in FIG. 1 is maximized. FIG. 2 is a plan view of a main part showing inner teeth of an outer rotor in the inscribed gear pump rotor shown in FIG. 1, and is a plan view showing a position where a missing correction part is formed based on a meshing point and a contact point. It is a principal part top view which shows the external tooth of the inner rotor in the internal gear pump rotor shown in FIG. FIG. 6 is an enlarged plan view of a main part of an internal gear pump rotor according to a second embodiment of the present invention, showing a contact state between the inner teeth of the inner rotor and the outer teeth of the outer rotor when the volume of the cell is minimized. is there. It is a figure which shows the conveyance efficiency and mechanical efficiency of an internal gear pump which have the internal gear pump rotor which concerns on the Example and comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inner rotor 11 External tooth 11a External tooth tip 11b External tooth groove part 20 Outer rotor 21 Internal tooth 21a Internal tooth tip part 21b Internal tooth groove part 21c Internal tooth top part 21d Internal tooth Groove bottom portion 30 Casing 40 Missing correction portion 50 Swelling correction portion Ai first circumscribed circle Ao second circumscribed circle Bi first inscribed circle Bo second inscribed circle Di first basic circle Do second basic Yen S cell

Claims (4)

an inner rotor formed with n (n is a natural number) external teeth and an outer rotor formed with (n + 1) internal teeth meshing with the external teeth,
An internal gear pump rotor that conveys fluid by sucking and discharging fluid by a volume change of a cell formed between tooth surfaces of both rotors when the rotors are engaged with each other,
The external teeth of the inner rotor are shaped based on an abduction cycloid curve created by an abduction circle in which the tooth profile of the tooth tip part circumscribes the first basic circle and rolls without slipping, and the tooth gap part Is a shape based on an inversion cycloid curve created by an inversion circle inscribed in the first basic circle and rolling without slipping,
The inner teeth of the outer rotor are shaped based on an inversion cycloid curve created by an inversion circle in which the tooth profile of the tooth tip portion is inscribed in the second basic circle and rolls without slipping, and the tooth gap portion Is a shape based on an abduction cycloid curve created by an abduction circle that circumscribes the second basic circle and rolls without slipping,
At least on the rear side in the rotational direction of the inner teeth of the outer rotor, the missing correction part that has lost the meat part forming the inner teeth on the basis of the cycloid curve has the following formula:
0.1 ≦ b / (a + b) ≦ 0.5
And −0.2 ≦ c / d ≦ 0.2
However,
a: Distance in the normal direction between the end of the missing tooth correction portion on the tooth tip side of the internal tooth and the second basic circle b: The end of the missing correction portion on the tooth tip side of the internal tooth, and the internal tooth Distance c in the normal direction to the top of the tooth tip of the tooth d: distance in the normal direction between the end of the missing correction portion on the tooth gap side of the internal tooth and the second basic circle d: the second basic circle An inscribed gear pump rotor, characterized in that it is formed in a portion satisfying a distance in a normal direction from a tooth bottom portion of a tooth. The inscribed gear pump rotor according to claim 1,
At least on the front side in the rotational direction of the outer teeth of the inner rotor, a bulge correcting portion that bulges a meat portion forming the outer teeth outward with respect to the cycloid curve is provided between the outer teeth and the outer rotor. The internal gear pump rotor is formed so as to have a surface shape that follows the surface shape of the missing correction portion when the inner teeth of the cell mesh with each other and the volume of the cell is minimized. The inscribed gear pump rotor according to claim 1 or 2,
At least one of the inner rotor and the outer rotor is made of a synthetic resin having a viscoelastic property. An inscribed gear pump rotor according to any one of claims 1 to 3,
A casing formed with a suction port for sucking fluid and a discharge port for discharging fluid;
A DC motor that rotationally drives the inner rotor,
An internal gear pump characterized in that a fuel used for an internal combustion engine or the like is sucked and discharged by a change in volume of a cell formed between the tooth surfaces of the rotors to convey the fuel.

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