JP2005194890A - Inscribed gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal gear pump capable of reducing the sliding resistance thereof and also minimizing the occurrence of noises and a reduction in the efficiency of a pump even by such a structure. <P>SOLUTION: This internal gear pump conveys a fluid by sucking/discharging the fluid when an outer rotor 20 having an internal gear 21 and an inner rotor 10 having an external gear 11 are meshed with each other and rotated. The inner diameter of a hole 31 for storing both rotors 10 and 20 formed in a casing 30 is set larger by 0.1 to 0.6 mm than the outer diameter of the outer rotor 20, and where an eccentric amount between the inner rotor 10 and the outer rotor 20 is er and an eccentric amount between the inner rotor 10 and the casing 30 is eh, the requirement of 0.005 mm ≤ (eh-er) ≤ 0.030 mm is satisfied. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an internal gear pump that sucks and discharges fluid by a volume change of a cell formed between tooth surfaces of both rotors when an inner rotor and an outer rotor are engaged with each other and rotate.

  Conventionally, an internal gear pump has an inner rotor having n outer teeth, an outer rotor formed with n + 1 inner teeth meshing with the outer teeth, a suction port through which fluid is sucked, and fluid is discharged. A casing formed with a discharge port, and with both rotors housed in holes formed in the casing, the outer rotor meshes with the inner teeth by rotating the inner rotor connected to the drive shaft. The fluid is sucked and discharged by changing the volume of a plurality of cells formed between the rotors.

  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 and rear sides in the direction of rotation, and independent fluid conveyance that rotates and moves as the inner rotor rotates. Make up the room. Each cell has a minimum volume during the process of meshing between the external teeth and the internal teeth, and then expands the volume while moving along the suction port to suck fluid from the suction port. Then, the cell whose volume is maximized decreases the volume while moving along the discharge port, and discharges fluid from the discharge port (see, for example, Patent Document 1).

The inner rotor and the outer rotor are arranged eccentrically by a predetermined amount, and the outer rotor and the hole of the casing are arranged coaxially.
Since the internal gear pump having such a configuration is small and has a simple structure, it is widely used as a lubricant pump for automobiles, an oil pump for automatic transmissions, and the like. As a drive means for this pump when mounted on an automobile, there is a crankshaft direct drive that is driven by the rotation of the engine with an inner rotor directly connected to the crankshaft of the engine.

  By the way, for the convenience of assembly, such an inscribed gear pump is generally set to such a size that each of the members has a predetermined play when the gear pump is formed. That is, the inner diameter of the through hole drilled in the central portion of the inner rotor is about 0.1 mm to 0.6 mm larger than the outer diameter of the drive shaft inserted into the through hole, and is formed in the casing. The inner diameter of the hole is about 0.1 mm to 0.6 mm larger than the outer diameter of the outer rotor. As described above, the outer rotor and the hole of the casing are coaxially arranged. In other words, a clearance of about 0.05 mm to 0.3 mm is provided between the outer circumferential surface of the outer rotor and the inner circumferential surface of the hole formed in the casing over the entire circumference.

  Therefore, when the inscribed gear pump configured as described above is driven, the inner rotor is approximately 0.05 mm in the radial direction with respect to the central axis of the drive shaft due to the clearance between the inner rotor and the drive shaft. It is rotated while swinging about 0.3 mm, and due to the clearance between the outer rotor and the hole formed in the casing, the outer rotor is about 0.05 mm in the radial direction with respect to the central axis of the casing hole. It is rotated while swinging about 0.3 mm. For this reason, the outer teeth of the inner rotor collide with the inner teeth of the outer rotor, and the outer peripheral surface of the outer rotor collides with the inner peripheral surface of the hole formed in the casing by the driving force received by the outer rotor at this time. There is a case. Therefore, when the inscribed gear pump is driven, noise is generated and the pump efficiency may be reduced.

As a means for suppressing the occurrence of a collision between the outer peripheral surface of the outer rotor and the inner peripheral surface of the hole formed in the casing, conventionally, an inlay is formed at the radial center portion of the inner rotor. A configuration is adopted in which the groove portion formed in the bottom surface of the hole of the casing is inserted, the swinging of the inner rotor is suppressed, and the collision between the outer peripheral surface of the outer rotor and the inner peripheral surface of the hole of the casing is avoided. Yes.
Japanese Patent No. 3293507

  However, in the prior art, a sliding resistance is generated between the spigot formed in the inner rotor and the groove formed in the casing, and the amount of energy loss due to this sliding resistance is generated when the internal gear pump is driven. This accounted for about 25% of the total energy loss, and there was a limit to further increase the efficiency of this gear pump.

  The present invention has been made in view of such circumstances, and it is possible to reduce the sliding resistance of the internal gear pump. Even with such a configuration, noise generation and pump efficiency can be reduced. An object of the present invention is to provide an internal gear pump that can suppress the reduction to a minimum.

In order to solve the above-described problems and achieve such an object, the present invention proposes the following means.
According to the first aspect of the present invention, there is provided an inner rotor formed with n (n is a natural number) external teeth, an outer rotor formed with n + 1 internal teeth meshing with the external teeth, and suction for fluid intake And a casing formed with a discharge port through which fluid is discharged, and by sucking and discharging fluid by the volume change of cells formed between the tooth surfaces of both rotors when both rotors mesh and rotate. An internal gear pump for transporting fluid, wherein an inner diameter of a hole formed in the casing for accommodating both rotors is set to be 0.1 mm or more and 0.6 mm or less larger than an outer diameter of the outer rotor, When the amount of eccentricity between the inner rotor and the outer rotor is er, and the amount of eccentricity between the inner rotor and the hole formed in the casing is eh,
0.005 mm ≦ (eh-er) ≦ 0.030 mm
It is characterized by satisfying.

According to the present invention, the inner peripheral surface of the hole formed in the casing and the outer peripheral surface of the outer rotor at the meshing position where the outer teeth of the inner rotor and the inner teeth of the outer rotor mesh with each other and the volume of the cell is minimized. The distance is minimized.
Therefore, the driving force is transmitted from the outer teeth of the inner rotor to the inner teeth of the outer rotor, the outer rotor moves to the front side in the rotational direction in the tangential direction of the meshing position of the rotor, and on the inner peripheral surface of the hole of the casing. When attempting to rotate by moving along, the movement toward the front side in the rotation direction is restricted by the inner peripheral surface of the hole formed in the casing.
This stabilizes the arrangement position of the outer rotor in the casing hole, so that the collision between the outer teeth of the inner rotor and the inner teeth of the outer rotor, and the outer peripheral surface of the outer rotor and the inner peripheral surface of the hole of the casing. Collisions are minimized. Even if these collisions occur, the amount of collision energy at this time is minimized.

Further, when the outer rotor is restrained from moving forward in the rotation direction and is along the inner peripheral surface of the hole of the casing, the amount of movement toward the position facing the meshing position and the rotation center is not limited. The outer rotor is urged to the opposite position. As a result, the occurrence of collision between the outer teeth of the inner rotor and the inner teeth of the outer rotor at this facing position is suppressed.
Furthermore, since the distance between the inner peripheral surface of the casing hole and the outer peripheral surface of the outer rotor is ensured to the maximum at the facing position, the outer peripheral surface of the outer rotor and the inner peripheral surface of the casing hole at the opposing position collide with each other. Occurrence is suppressed.

  From the above, it is not necessary to adopt a configuration in which an inlay is formed in the radially central portion of the inner rotor and this inlay is inserted into a groove formed in the bottom surface of the hole of the casing, and the collision between the outer rotor and the casing, and It is possible to suppress the occurrence of collision between the outer teeth of the inner rotor and the inner teeth of the outer rotor. Accordingly, it is possible to reduce the sliding resistance of the inscribed gear pump, and even with such a configuration, it is possible to minimize noise generation and reduction of pump efficiency.

  According to the internal gear pump of the present invention, it is possible to reduce the sliding resistance of the internal gear pump, and even with such a configuration, noise generation and reduction in pump efficiency are minimized. Can be suppressed.

An embodiment of an inscribed gear pump according to the present invention will be described with reference to FIGS. 1 and 2.
The internal gear pump shown in FIG. 1 has an inner rotor 10 formed with eight external teeth 11, an outer rotor 20 formed with nine internal teeth 21 that mesh with the external teeth 11, and fluid is sucked. And a casing 30 formed with a discharge port through which fluid is discharged.
A hole 31 is formed in the casing 30, and the rotors 10 and 20 are accommodated in the hole 31. Note that the suction port and the discharge port are not shown in FIG.

  The inner rotor 10 has a through hole 12 formed in the central portion in the radial direction, and the inner diameter is about 0.1 mm to 0.6 mm larger than the outer diameter of the drive shaft inserted into the through hole 12. Yes. The drive shaft is directly connected to a crankshaft of an engine (not shown), so that the inner rotor 10 is supported by the rotation of the engine so as to be rotatable in the circumferential direction around the axis O1 in the casing 30. It has been configured. Therefore, the axis O1 is not only the center of rotation of the inner rotor 10 and the drive shaft, but also the center of the through hole 12.

  The outer rotor 20 is arranged with the shaft center O2 being eccentric (eccentricity: er) with respect to the shaft center O1 of the inner rotor 10, and the inner teeth 21 are meshed with the outer teeth 11, and the casing is centered on the shaft center O2. 30 is rotatably supported in the circumferential direction.

  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.

By the way, the eccentricity er between the axis O1 of the inner rotor 10 and the axis O2 of the outer rotor 20 is obtained by sequentially connecting the tops of the tooth tips 11a of the outer teeth 11 of the inner rotor 10 in the circumferential direction. The circular diameter, that is, the large diameter of the inner rotor is defined as d, and the circular diameter obtained by sequentially connecting the bottoms of the tooth groove portions 11b of the external teeth 11 of the rotor 10 in the circumferential direction, that is, the small diameter of the inner rotor 10 is defined. When D, the following equation is obtained.
er = (d−D) / 4

Both rotors 10 and 20 are meshed with each other by their tooth surface shapes and rotated by the rotation of the drive shaft. A cell S that is a fluid transfer chamber is formed between the meshing points of the rotors 10 and 20 that mesh with each other. A suction port and a discharge port that open to the cell S are formed in the casing 30, and fluid exchange with each cell S is performed from the suction port and the discharge port.
The volume of the cell S changes as the rotors 10 and 20 rotate, so that the fluid is sucked from the suction port in the process of expanding the volume of the cell S, and the process of reducing the volume of the cell S The fluid is discharged from the discharge port.

As described above, the casing 30 is formed with the hole 31 for accommodating both the rotors 10 and 20. The inner diameter of the hole 31 is about 0.1 mm or more and 0.6 mm or less larger than the outer diameter of the outer rotor 20. ing. As shown in FIG. 1, the center O3 of the hole 31 is 0 from the axis O2 of the outer rotor 20 in a direction away from the axis O1 of the inner rotor 10 and the meshing position A across the axis O2. 0.005 mm or more and 0.030 mm or less, more preferably 0.010 mm or more and 0.020 mm or less. That is, when the amount of eccentricity between the inner rotor 10 and the outer rotor 20 is er, and the amount of eccentricity between the inner rotor 10 and the hole 31 of the casing 30 is eh,
0.005 mm ≦ (eh-er) ≦ 0.030 mm
It has a configuration that satisfies.
The meshing position A is a position where the rotational driving force of the inner rotor 10 is transmitted to the outer rotor 20 as shown in FIG.

Thereby, as shown in FIG. 1, the clearance t between the inner peripheral surface of the hole 31 of the casing 30 and the outer peripheral surface of the outer rotor 20 has a minimum clearance tA at the meshing position A, and the clearance tA rotates from this position A. The clearance tB is gradually increased from the meshing position A toward the position B so that the clearance tB at the circumferential position B shifted by 180 ° to the front side or the rear side is maximized.
As described above, the clearance tA at the meshing position A is 0.020 mm or more and 0.295 mm or less, and the clearance tB at the position B is 0.055 mm or more and 0.330 mm or less.
In FIG. 1, the hole 31 of the casing 30 is drawn greatly for convenience of explanation.

Here, specification values of the inner rotor 10, the outer rotor 20, and the casing 30 shown in FIG. 1 are shown in FIG. 2 (a) and FIG. 2 (b) together with the comparative example 1 as the prior art.
In FIG. 2 (a), the large diameter of the outer rotor indicates a circular diameter obtained by sequentially connecting the bottoms of the tooth groove portions 21b of the respective internal teeth 21 in the circumferential direction. The circular diameter obtained by sequentially connecting the tops of the tooth tips 21a of the teeth 21 in the circumferential direction is shown.
Here, in both Example 1 and Comparative Example 1 shown in FIG. 2, the inner diameter of the hole formed in the casing, in which the two rotors are accommodated, is 79.99 mm or more and 80.01 mm or less. The outer diameter of the outer peripheral surface of the outer rotor facing the surface is 79.75 mm or more and 79.80 mm or less.

As shown in FIG. 2B, the first embodiment does not change the positions of the inner rotor 10 (axial center O1) and the hole 31 (center O3) of the casing 30 as compared with the first comparative example. The position of the outer rotor 20 (axial center O2) is shifted by 0.015 mm toward the meshing position A side, that is, the lower side of the paper surface in FIG. 1, and the eccentricity er is made 0.015 mm smaller than that of the first comparative example. Yes. Then, in the meshing position A, a gap is generated between the tooth tip portion 11a of the external tooth 11 and the tooth groove portion 21b of the internal tooth 21 at the meshing position A. Since the gap between the tooth tip portion 11a of the tooth 11 and the tooth groove portion 21b of the internal tooth 21 becomes small and the meshing state of the gear pump changes, in order to maintain this meshing state, as shown in FIG. As described above, the diameter of the first abduction circle Ai that creates the tooth tip portion 11a of the external tooth 11 is reduced by 0.030 mm, and the diameter of the second abduction circle Ao that creates the tooth gap portion 21b of the internal tooth 21 Is reduced by 0.030 mm.
Here, as described above, since the eccentricity er is calculated from the large diameter d and the small diameter D of the inner rotor, in other words, the tooth heights of both rotors are compared with those of Comparative Example 1 as the prior art. The first embodiment is realized by making it smaller by 0.015 mm.

  As described above, the clearance tA between the inner peripheral surface of the hole 31 of the casing 30 and the outer peripheral surface of the outer rotor 20 at the meshing position A can be suppressed to a minimum. The meshing state between the inner teeth 11 and the inner teeth 21 can be maintained equivalent to the conventional one.

As described above, according to the internal gear pump according to the present embodiment, the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 are engaged with each other at the engagement position A where the volume of the cell S is minimized. The clearance tA between the inner peripheral surface of the hole 31 formed in the casing 30 and the outer peripheral surface of the outer rotor 20 can be minimized.
Accordingly, the driving force is transmitted from the outer teeth 11 of the inner rotor 10 to the inner teeth 21 of the outer rotor 20, the outer rotor 20 moves to the front side in the rotational direction in the tangential direction of the meshing position A of the rotor 20, and the casing. When an attempt is made to rotate along the inner peripheral surface of the 30 hole 31, this forward movement in the rotational direction is restricted by the inner peripheral surface of the hole 31 of the casing 30.
Thereby, since the arrangement position of the outer rotor 20 in the hole 31 of the casing 30 is stabilized, the outer teeth 11 of the inner rotor 10 collide with the inner teeth 21 of the outer rotor 20, and the outer peripheral surface of the outer rotor 20 and the casing. The occurrence of collision with the inner peripheral surface of the 30 holes 31 can be minimized. Even if these collisions occur, the amount of collision energy at this time can be minimized.

Further, when the outer rotor 20 is restrained from moving forward in the rotational direction and is along the inner peripheral surface of the hole 31 of the casing 30, the rotor 20 is rotated 180 degrees from the meshing position A to the front side or the rear side in the rotational direction. The amount of movement toward the circumferential position B deviated is increased by the amount of restraint, that is, the outer rotor 20 is biased to the position B. Thereby, the collision of the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 at this position B can be suppressed.
Further, since the distance tB between the inner peripheral surface of the hole 31 of the casing 30 and the outer peripheral surface of the outer rotor 20 at the position B is secured to the maximum, the outer peripheral surface of the outer rotor 20 and the hole 31 of the casing 30 at this position B are secured. It is possible to suppress the occurrence of collision with the inner peripheral surface.

  As described above, it is not necessary to adopt a configuration in which an inlay is formed in the central portion in the radial direction of the inner rotor 20 and this inlay is inserted into a groove formed in the bottom surface of the hole 31 of the casing 30. And the occurrence of a collision between the outer teeth 11 of the inner rotor 10 and the inner teeth 21 of the outer rotor 20 can be suppressed. Therefore, it is possible to greatly reduce the sliding resistance of the inscribed gear pump, and even in such a configuration, it is possible to suppress noise generation and reduction in pump efficiency to a minimum.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the said embodiment, although the tooth profile formed based on the cycloid curve was shown as the external tooth 11 of the inner rotor 10, and the internal tooth 21 of the outer rotor 20, it does not restrict to this, For example, it forms based on a trochoid curve. Even a tooth profile that has been made is applicable. The specification values according to the present invention in this case are shown as Example 2 in FIG. 3 together with Comparative Example 2 as the prior art. In both Example 2 and Comparative Example 2 shown in this figure, the inner diameter of the hole formed in the casing, in which the rotors are accommodated, is 59.99 mm or more and 60.01 mm or less, and faces the inner peripheral surface of the hole. The outer diameter of the outer peripheral surface of the outer rotor is 59.80 mm or more and 59.85 mm or less, the number of external teeth of the inner rotor is 9, and the number of internal teeth of the outer rotor is 10. Even in this case, the same effects as those of the above-described embodiment can be obtained.

  Moreover, in the said embodiment, although the inner rotor 10 was connected with the drive shaft directly connected with the crankshaft of the engine and the structure of the crankshaft direct drive driven by this engine rotation was shown, it is not restricted to this. For example, the present invention is also applicable to an internal gear pump that transports a fuel such as a light oil having a relatively high viscosity by driving a DC motor having a relatively small driving force. In other words, as described above, the present invention can realize a so-called inlay-less configuration without causing problems such as the occurrence of a collision, so that a significant reduction in sliding resistance can be realized.

Furthermore, in the said embodiment, as shown in FIG. 1, among the extension lines obtained by connecting the center O3 of the hole 31 of the casing 30 with the axis O1 of the inner rotor 10 and the axis O2 of the outer rotor 20, Although the configuration is shown in which the center O3 is disposed on the opposite side of the axis O1 and the meshing position A across the axis O2, the center O3 is not limited to this, and the center O3 of the inner rotor 10 is the center. On the circumference of the radius eh, the axis O2 is sandwiched so that the angle between the straight line obtained by connecting the axis O1 and the center O3 and the extension line is 0 ° or more and 30 ° or less. You may arrange | position in the part located in the other side of the axial center O1 and the meshing position A. FIG.
Even in this case, the same effects as those of the above-described embodiment are obtained.

  It is possible to reduce the sliding resistance of the internal gear pump, and even with such a configuration, it is possible to provide an internal gear pump that can suppress noise generation and reduction in pump efficiency to a minimum.

It is a top view which shows the internal gear pump by one Embodiment of this invention. It is the item value shown as 1st Embodiment of the inscribed gear pump shown in FIG. It is a specification value of the internal gear pump by 2nd Embodiment of this invention.

Explanation of symbols

10 Inner rotor 20 Outer rotor 30 Casing 31 Hole S cell er Eccentricity between inner rotor and outer rotor eh Eccentricity between inner rotor and hole formed in casing

Claims (1)

Inner rotor formed with n (n is a natural number) external teeth, outer rotor formed with n + 1 internal teeth meshing with the external teeth, a suction port for sucking fluid, and a discharge for discharging fluid And an internal gear pump that conveys fluid by sucking and discharging fluid by a change in volume of cells formed between the tooth surfaces of both rotors when both rotors mesh with each other and rotate. Because
The inner diameter of the hole in which the two rotors are accommodated formed in the casing is set to be larger by 0.1 mm or more and 0.6 mm or less than the outer diameter of the outer rotor,
When the amount of eccentricity between the inner rotor and the outer rotor is er, and the amount of eccentricity between the inner rotor and the hole formed in the casing is eh,
0.005 mm ≦ (eh-er) ≦ 0.030 mm
An inscribed gear pump characterized by satisfying

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