JP2008138601A - Inscribed gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce noise and a drive torque loss of an inscribed gear pump in which at least a gear profile of an inner rotor is formed of a cycloid curve. <P>SOLUTION: In an inscribed gear pump in which the difference of the number of gear teeth between the inner rotor and an outer rotor is one, the gear profile of the inner rotor 1 of the pump is formed by using two basic circles. Here, an addendum 1a has a locus (outer rolling cycloid curve) of a point at the outer periphery of a second rolling circle bi circumscribed by a second base circle Di2, and a dedendum 1b is formed of a locus (inner rolling cycloid curve) of a point of a first rolling circle ai inscribed with a first base circle Di1 with a diameter greater than its second base circle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal gear pump having an inner rotor having a tooth profile formed in a cycloid curve, and more specifically, a pump rotor configured by combining an inner rotor and an outer rotor to smoothly rotate and generate noise such as meshing noise. The present invention relates to an internal gear pump that reduces the loss of drive torque.

  Internal gear pumps are widely used as oil pumps for car engines and automatic transmissions. Among the internal gear type pumps, there is one in which the tooth profile of the rotor is formed by a cycloid curve (see Patent Documents 1 to 6 below).

  Patent Document 1 discloses an internal gear in which tooth shapes of an inner rotor and an outer rotor are formed by a cycloid curve drawn by a trajectory of an inversion circle and an outer rotation circle that are in contact with the basic circle and roll without slipping on the basic circle. Disclosed is a pump. The inner and outer rotation circles use four rolling circles with different diameters. The tooth tip of the inner rotor and the tooth bottom of the outer rotor are abduction cycloid curves, and the tooth tip of the outer rotor and the tooth bottom of the inner rotor are Each is formed by an adduction cycloid curve.

  Further, in Patent Document 2, the center of the inner rotor whose root is formed by an inversion cycloid curve is rotated around the center of the outer rotor, and the outer rotor is represented by an envelope of the tooth profile curve group of the inner rotor at this time. An internal gear pump in which the tooth profile is created is disclosed.

  Further, Patent Documents 3 to 6 disclose that the cycloid curve forming the tip of the inner rotor or the outer rotor is divided into two equal parts at the center (vertex), and the curves are separated by a predetermined amount or shortened. .

  In the internal gear pumps disclosed in these patent documents, for example, the cycloid curves of the tooth tip and the tooth bottom of the inner rotor are drawn using the same basic circle.

  FIG. 7 shows the situation. The tooth tip 1a and the tooth bottom 1b of the inner rotor 1 are in contact with a basic circle having a diameter Di (referred to as a basic circle Di), and the two rolling diameters ai and bi are rolled without sliding on the basic circle. It is formed by the locus of one point on the outer circumference of each circle. An inversion circle with a diameter ai is an inversion circle (this is referred to as a second inversion circle ai), and draws an inversion cycloid curve of the root 1b. Moreover, the rolling circle of diameter bi is an abduction circle (this is called 1st rolling circle bi), and the abduction cycloid curve of the tooth tip 1a is drawn. The abductor cycloid curve forming the tooth tip and the adductor cycloid curve forming the tooth bottom each contact with each other on the basic circle Di by a 90-degree crossing angle with the basic circle Di in design. C is the intersection of the abduction cycloid curve and the adduction cycloid curve.

The diameter Di of the inner rotor base circle, the diameter ai of the second rolling circle, the diameter bi of the first rolling circle, the eccentricity e of the inner rotor and the outer rotor, and the number of teeth n of the inner rotor are established by the following equations: It is set to be.
Di = n (bi + ai)
ai + bi = 2e

Similarly, some outer rotors draw a cycloid curve of a tooth tip and a root using one basic circle. In this case, the basic circle is set to a size of (n + 1) * 2e.
JP 2003-56473 A JP 2004-353656 A JP 2005-68999 A JP 2005-69000 A JP 2005-69001 A JP 2005-69002 A

  When the abduction cycloid curve forming the tooth tip of the inner rotor and the adduction cycloid curve forming the tooth bottom are drawn using the same basic circle, as shown in FIG. A situation occurs in which the (inversion cycloid curve and abduction cycloid curve) are not accurately connected at the original position of the intersection C.

Since the change of the inclination θ shown in FIG. 9 is small in the vicinity of the basic circle Di, each cycloid curve of adduction and abduction is a conventional method of connecting two cycloid curves of adduction and abduction on the same basic circle. It is difficult to complement (correct) the shift of the joint due to a processing error, and a step is likely to occur at the position of the joint. Also, since the two cycloid curves of adduction and abduction need to be connected to each other at the point of intersection C where they intersect with the basic circle at an angle of 90 degrees, both cycloid curves are obtained when the tool for finishing the tooth surface bites in even a little. There may be an undercut at the joint. The undercut state refers to, for example, a state as shown in FIG. 8 in which the end of the adduction cycloid curve (the tooth bottom 1b) enters inside the end of the abduction cycloid curve (the tooth tip 1a).
9 is the angle between the tangent line of the tooth profile curve at one point A on the tooth profile curve and the tangent line P at the point A of the circle centering on the rotor center O passing through the point A. Point to.

  The undercut also creates a step between the two curves. Due to the level difference, a situation occurs in which the pump rotor cannot rotate smoothly, which causes noise. Further, since the smooth rotation is hindered, the driving torque loss also increases.

  An object of the present invention is to eliminate noise and drive torque loss of an internal gear pump in which at least the tooth profile of the inner rotor is formed with a cycloid curve without the above-described disadvantages.

  In order to solve the above-described problem, in the present invention, a basic circle that forms the tooth tip of the inner rotor and a basic circle that forms the tooth bottom are separated. Specifically, the inner rotor of the internal gear type pump that combines an inner rotor with n teeth and an outer rotor with (n + 1) teeth, with the tooth tip circumscribing the second basic circle. It is formed by the abduction cycloid curve created by the second rolling circle that rolls without sliding on the second basic circle, and its root is inscribed in the first basic circle having a diameter larger than that of the second basic circle. It is formed by the inversion cycloid curve created by the first rolling circle that rolls without sliding on the first basic circle.

  The inclination angles at the joints between the addendum cycloid curve of the tooth tip and the addendum cycloid curve of the root may be equal.

In this internal gear pump, the following (1) and (2) can be considered as the form of the outer rotor, and the object of the invention can be achieved by adopting either of them.
(1) The tooth tip is formed by an inversion cycloid curve created by a third rolling circle inscribed in the third foundation circle and rolling without slipping on the third foundation circle. An outer rotor formed by an abduction cycloid curve created by a fourth rolling circle circumscribing a fourth foundation circle having a smaller diameter than the circle and rolling on the fourth foundation circle.
(2) Revolve the center of the inner rotor around the center of the outer rotor by drawing a circle of diameter (2e + t), and rotate the inner rotor 1 / n times while the center of the inner rotor revolves around the circle An outer rotor in which the envelope of the inner rotor tooth profile curve group thus formed is an outer rotor tooth profile.
Where, e: the amount of eccentricity between the center of the inner rotor and the center of the outer rotor
t: Rotor clearance between the outer rotor and the inner rotor pressed against it
Maximum value of
n: Number of teeth of the inner rotor Note that the above definitions for e, t, and n also apply to the following.

In this invention, the basic circle is divided into two parts, a first basic circle and a second basic circle, and the tooth of the inner rotor is represented by a locus (an abduction cycloid curve) of one point on the outer periphery of the second rolling circle rolling on the second basic circle. The tip of the inner rotor is respectively drawn by a locus (inner cycloid curve) of the outer periphery of the first rolling circle rolling on the first basic circle having a diameter larger than that of the second basic circle Di2. By doing so, the abduction cycloid curve can be connected to the inversion cycloid curve before intersecting the second basic circle (before the inclination angle θ becomes 90 degrees), while the abduction cycloid curve is It can be connected to the abduction cycloid curve before crossing the basic circle (also before the inclination angle θ becomes 90 degrees).
The abduction cycloid curve has an inclination angle of 90 ° at the position intersecting the second basic circle, and the adduction cycloid curve has an inclination angle of 90 ° at the position intersecting the first basic circle.

Thereby, it becomes easy to avoid each cycloid curve of outer rotation and inner rotation being in an undercut state, and it is also easy to complement (correct) the shift of the joint. Misalignment of joints can be easily achieved by increasing the slope angle of the joint when both cycloid curves are too close to the design value, and conversely decreasing the slope angle of the joint when both cycloid curves are too far from the design value. It can be corrected. By correcting this deviation, the abduction cycloid curve and the inversion cycloid curve are connected without any step, so that the rotation of the pump rotor is smoothed, so that noise is reduced and loss of driving torque is also reduced.

  Embodiments of an internal gear pump according to the present invention will be described below with reference to FIGS. The internal gear pump 10 shown in FIG. 1 comprises a pump rotor 3 by combining an inner rotor 1 having n teeth and an outer rotor 2 having (n + 1) teeth, and this pump rotor 3 is sucked into the pump rotor 3. It is configured to be housed in a housing 6 having a port 4 and a discharge port 5. Oi is the rotation center of the inner rotor, Oo is the rotation center of the outer rotor, and Oi and Oo are decentered.

  A rotating shaft 7 is connected to the inner rotor 1. A driving force is transmitted from the rotating shaft 7 to the inner rotor 1 to rotate the inner rotor 1. At this time, the outer rotor 2 is driven to rotate. As the pump rotor 3 rotates, the volume of the chamber (pump chamber) 8 formed between the inner rotor 1 and the outer rotor 2 increases and decreases, and fluid such as oil is sucked and discharged.

  As shown in FIG. 2, the inner rotor 1 creates a tooth profile using two basic circles Di1 and Di2. Di1 is a first basic circle, and an inversion cycloid curve is created by the locus of one point of the outer circumference of the first rolling circle ai that is inscribed in the first basic circle Di1 and rolls without sliding on the first basic circle Di1. The root 1b is formed by the introductory cycloid curve. Di2 is the second basic circle, and an abduction cycloid curve is created by the locus of one point of the outer periphery of the second rolling circle bi that circumscribes the second basic circle Di2 and rolls without sliding on the second basic circle Di2. The tooth tip 1a is formed by the abduction cycloid curve.

The diameter of the first basic circle is Di1, the diameter of the second basic circle is Di2, the diameter of the first rolling circle inscribed in the first basic circle is ai, and the diameter of the second rolling circle circumscribed in the second basic circle is bi. Think. Among these, the diameter Di1 of the first basic circle and the diameter Di2 of the second basic circle can be determined as follows, for example. First, the inner rotor short diameter (tooth root diameter) dih is determined, and the inner rotor long diameter (tooth tip diameter) die is determined based on the formula die = dih + 4e. Next, the diameter ai of the first rolling circle is determined, and the diameter Di1 of the first basic circle is obtained by the formula Di1 = dih + 2ai.
Further, the diameter bi of the second rolling circle intersecting with the cycloid curve drawn by the locus of one point on the first rolling circle that rolls without sliding on the first basic circle is obtained, and further, Di2 = die-2bi. The diameter Di2 of the second basic circle is obtained from

  The abduction cycloid curve created by the first rotation circle ai and the abduction cycloid curve created by the second rotation circle bi can be connected to each other between the first basic circle Di1 and the second basic circle Di2.

It should be noted that at the joint, the abduction cycloid curve and the adduction cycloid curve may deviate from the design intersections due to inevitable machining errors or the like, and the two curves may not be directly connected. In that case, it is good to form a joint by the tangent (11 of FIG. 3) with respect to both an abduction cycloid curve and an adduction cycloid curve. If the joint between the abduction cycloid curve and the adduction cycloid curve is formed by tangents to both curves, the joints have the same inclination angle and the joints become smooth. Also, when the abduction cycloid curve and adduction cycloid curve are too close to the design value, the slope angle of the joint (tangent) is increased, and conversely, when both cycloid curves are too far apart from the design value, the slope angle of the tangent line is increased. By making it small, the shift can be easily corrected, and the joints can be easily processed.

  FIG. 4 shows details of an example of the outer rotor 2. The outer rotor 2 creates a tooth profile using two basic circles Do1 and Do2. Do1 is a third basic circle (the diameter of the circle is also assumed to be Do1), and an inversion cycloid curve is formed by a third rolling circle ao that is inscribed in the third basic circle Do1 and rolls without sliding on the third basic circle Do1. The tooth tip 2a is formed by the introductory cycloid curve. Do2 is a fourth basic circle (the diameter of the circle is also Do2), and an abduction cycloid curve is formed by a fourth rolling circle bo that circumscribes the fourth basic circle Do2 and rolls without sliding on the fourth basic circle Do2. And a tooth bottom 2b is formed by the abduction cycloid curve.

  In designing the outer rotor, the outer rotor short diameter (tooth tip diameter) doh is first determined, and the outer rotor long diameter (tooth bottom diameter) doe is determined based on the formula doe = doh + 4e. Next, the diameter ao of the third rolling circle is determined, and the diameter Do1 of the third basic circle is determined by the formula Do1 = doh + 2ao. Further, the diameter bo of the fourth rolling circle intersecting with the cycloid curve drawn by the locus of one point on the third rolling circle ao rolling without sliding on the third basic circle Do1, and the formula of Do2 = doe-2bo The diameter Do2 of the 4th foundation circle by is calculated. The third rolling circle ao is inscribed in the third basic circle Do1 whose diameter is determined in this way, and the third rolling circle ao is rolled without sliding to draw an inversion cycloid curve of the tooth tip 2a. Further, the fourth rolling circle bo is circumscribed on the fourth basic circle Do2, and the fourth rolling circle bo is rolled without sliding to draw an abduction cycloid curve of the tooth bottom 2b. Then, the abduction cycloid curve and the addendum cycloid curve of the tooth tip 2a can be connected between the third basic circle Do1 and the fourth basic circle Do2. Also in this case, similarly to the inner rotor 1, the tooth tip and the tooth bottom, that is, the inversion cycloid curve and the abduction cycloid curve can be smoothly connected.

  The diameter ao of the third rolling circle is preferably set so that ai> ao for smooth rotation of the rotor, and the diameter bo of the fourth rolling circle is set to bo> bi.

  5 and 6 show another example of a method for creating a tooth profile of the outer rotor. Using the inner rotor 1 of the present invention in which the tooth profile of the cycloid curve is formed using the first basic circle and the second basic circle, the center Oi of the inner rotor 1 is set around the center Oo of the outer rotor as shown in FIG. A circle (2e + t) with a diameter (2e + t) is drawn and revolved, and the inner rotor is rotated 1 / n times while the inner rotor center Oi revolves around the circle S. The envelope of the inner rotor tooth profile curve group thus created 12 (see FIG. 6) is the tooth profile of the outer rotor 2.

  The tooth profile created in this way smoothly connects the tooth tip and the tooth bottom. Therefore, the pump in which the outer rotor 2 having the tooth profile is combined with the inner rotor using the tooth profile is also smoothly rotated, and the effects of reducing noise and reducing driving torque loss can be obtained.

FIGS. 10A and 10B show a more detailed embodiment of the pump rotor used in the internal gear pump of the present invention. The illustrated pump rotor includes an inner rotor 1 having an eccentricity of 3.10 mm and 10 teeth, and an outer rotor 2 having 11 teeth. The dimensions of the inner rotor 1 and the outer rotor 2 are as follows.
-Inner rotor-
Short diameter dih: 57.65 mm
Long diameter die: 70.050 mm
Inner diameter di: φ40mm
First rolling circle ai (see FIG. 2): 3.20 mm
First basic circle Di1 (see FIG. 2): 64.050 mm
Second rolling circle bi (see FIG. 2): 3.20 mm
Second basic circle Di2 (see FIG. 2): 63.650 mm
Tilt angle θ (see FIG. 9): 80 °
-Outer rotor-
Short diameter doh: 63.970mm
Long diameter doe: 76.370 mm
Outer diameter do: φ85mm
Third rolling circle ao (see FIG. 4): 3.131 mm
Third basic circle Do1 (see FIG. 4): 70.232 mm
Fourth rolling circle bo (see FIG. 4): 3.251 mm
Fourth basic circle Do2 (see FIG. 4): 69.868 mm
Tilt angle θ (see FIG. 9): 80 °

  It was confirmed by experiments that the pump employing the pump rotor of this embodiment was smoothly rotated, and that the effect of reducing noise and driving torque loss was obtained as compared with the conventional product.

The figure which shows embodiment of the internal gear type pump of this invention in the state which removed the cover The figure which shows the creation state of the tooth profile of the inner rotor The figure which shows the state which connected each cycloid curve of adduction and abduction with tangent The figure which shows an example of the creation state of the tooth profile of an outer rotor Diagram showing tooth profile displacement when the inner rotor revolves while rotating. The figure which shows the tooth profile of the outer rotor formed with the envelope of the inner rotor tooth profile curve group The figure which shows the example which draws the tooth tip and tooth bottom of an inner rotor using one basic circle The figure which shows the state where the level difference has occurred in the joint where the joint of the tooth tip and the tooth bottom is in an undercut state Illustration of the definition of the tilt angle θ The figure which shows the inner rotor and outer rotor which were employ | adopted for the pump of the Example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner rotor 1a Tooth tip 1b Tooth bottom 2 Outer rotor 2a Tooth tip 2b Tooth bottom 3 Pump rotor 4 Suction port 5 Discharge port 6 Housing 7 Rotating shaft 8 Chamber 10 Internal gear type pump 11 Tangential line 12 Envelope line Di1 First basic circle Di2 2nd basic circle Do1 3rd basic circle Do2 4th basic circle ai 1st rolling circle bi 2nd rolling circle ao 3rd rolling circle bo 4th rolling circle

Claims (4)

In the internal gear pump in which the inner rotor (1) having n teeth and the outer rotor (2) having (n + 1) teeth are combined,
The inner rotor (1)
The tooth tip (1a) is formed by an abduction cycloid curve created by a second rolling circle (bi) that circumscribes the second basic circle (Di2) and rolls without sliding on the second basic circle, The root (1b) is inscribed by the first rolling circle (ai) that is inscribed in the first basic circle (Di1) having a larger diameter than the second basic circle (Di2) and rolls on the first basic circle without slipping. An internal gear pump characterized in that it is formed by an introductory cycloid curve created.   2. The internal gear pump according to claim 1, wherein an inclination angle of a joint of the abduction cycloid curve and the inversion cycloid curve is made equal. The outer rotor (2) is
The tooth tip (2a) is formed by an inversion cycloid curve created by a third rolling circle (ao) inscribed in the third basic circle (Do1) and rolling without slipping on the third basic circle, The root (2b) is created by a fourth rolling circle (bo) that circumscribes the fourth basic circle (Do2) having a smaller diameter than the third basic circle (Do1) and rolls on the fourth basic circle without slipping. 3. The internal gear pump according to claim 1, wherein the internal gear pump is formed by a generated abduction cycloid curve. The outer rotor (2) is
The center (Oi) of the inner rotor (1) is revolved by drawing a circle with a diameter (2e + t) around the center (Oo) of the outer rotor, and the center of the inner rotor (Oi) is 1 on the circle with the diameter (2e + t). The inner rotor (1) is rotated 1 / n times during the revolution, and the envelope (12) of the inner rotor tooth profile curve group thus formed is the tooth profile of the outer rotor. The internal gear pump according to 1 or 2.
Where, e: the amount of eccentricity between the center of the inner rotor and the center of the outer rotor
t: Rotor clearance between the outer rotor and the inner rotor pressed against it
Maximum value of
n: Number of teeth of inner rotor

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