JP5561287B2 - Outer rotor tooth profile creation method and internal gear pump - Google Patents

Description

  The present invention relates to a method for generating a tooth profile of an outer rotor constituting an internal gear pump and an internal gear pump employing the method.

  An internal gear pump configured by combining an inner rotor with n teeth and an outer rotor with (n + 1) teeth in an eccentric arrangement, and storing the pump rotor consisting of the two in the rotor chamber of the housing, It is used as an oil pump for automobile engine lubrication and automatic transmission (AT).

  The internal gear pump has a suction port and a discharge port on the end face of the rotor chamber of the housing. The end between the suction port end and the discharge port start end is configured as a closed portion that separates the chamber (pump chamber) created between the teeth of the inner rotor and the outer rotor from the suction port and the discharge port, and the chamber faces the suction port. Then, the liquid is sucked into the chamber while moving while expanding the area (volume), and the liquid in the chamber is sent out to the discharge port while moving toward the discharge port while reducing the area.

Among the internal gear pumps, there are those described in the following a) and b).
a) By a tooth tip drawn by the locus of one point of an abduction circle rolling without slipping on the first basic circle, and by a locus of one point of an inversion circle rolling without slipping on the second basic circle having a smaller diameter than the first basic circle A pump having a tooth profile in which the drawn roots are connected by an involute curve (see Patent Document 1). The rotor of this pump is called a Mega Floyd (registered trademark of Sumitomo Electric) rotor.

b) A pump employing a tooth profile created by the method disclosed in Patent Document 2 (method I described later). The detailed description of the tooth profile creation method of Patent Document 2 will be given later.

  The internal gear pumps of Patent Documents 1 and 2 above alleviate the restriction on the setting of the tooth length of the inner rotor and the outer rotor, and the tooth height is higher than that of a pump having a tooth profile based on a trochoid curve or a cycloid curve. Can be bigger. Therefore, the volume of the chamber can be increased to increase the discharge amount of the pump, and the pump performance can be improved.

  In addition, the inner rotor having the tooth profile of Patent Documents 1 and 2 can realize a relatively smooth pump rotor when the tooth profile of the outer rotor combined therewith is created by the method described in Patent Document 3 below. The tooth profile of the outer rotor is created by the method of Patent Document 3 (method II described later).

Japanese Patent No. 4557514 Japanese Patent No. 4600844 No. 6-39109

  In an internal gear pump in which an inner rotor having n teeth and an outer rotor having (n + 1) teeth are combined, a predetermined tip clearance (tooth tip) is provided between the inner rotor and the outer rotor so that the pump rotates smoothly. Clearance).

  In other words, the center of the inner rotor and the center of the outer rotor are arranged at a predetermined eccentric position, and one of the top tips of the inner rotor and the bottom of the bottom of the outer rotor is on the linear eccentric axis where the centers of both rotors are placed. The desired position between the inner rotor and the outer rotor in an arbitrary theoretical arrangement in which the inner rotor and the outer rotor are rotated at a ratio of (n + 1): n from the reference position with reference to this position. Each tooth profile of the inner rotor and the outer rotor is designed so as to ensure the tip clearance.

  However, during actual pump rotation, the inner rotor and outer rotor mesh at least at one location, resulting in a state different from the theoretically arranged state (a state shifted from the position in the rotational direction). It will be different from the above numbers.

  Due to the difference and inevitable machining errors that occur in the manufacturing process, depending on the rotation angle of the inner rotor, the tip clearance may be minimized at locations other than the meshing part, or the tooth surfaces of the inner rotor and outer rotor may contact (interfere). Sometimes.

  The problem of minimizing the tip clearance and interference of the tooth surface is particularly likely to occur in pumps with a small tip clearance setting value and pumps having a rotor with a large tooth height as in Patent Documents 1 and 2 above. Is concerned.

  Therefore, the present invention secures an appropriate interdental gap between the inner rotor and the outer rotor at a place other than the meshing portion in actual use for the internal gear pump in which the inner rotor and the outer rotor having one tooth difference are combined. To be. Therefore, an object of the present invention is to provide a tooth profile creation method for the outer rotor and an internal gear pump that creates the tooth profile of the outer rotor by the method.

  In order to solve the above-described problems, in the present invention, the inner rotor having n teeth and the outer rotor having (n + 1) teeth having a correction front tooth profile are meshed with each other at a predetermined eccentric arrangement position. Inner rotor center where the tooth surface of the rotor is to be secured between the outer rotor and the outer rotor at a location other than the meshing portion with the outer rotor and where there is a concern about minimization between teeth or interference of teeth The inner rotor offset tooth surfaces that are obtained by offsetting the outer surface greatly and repetitively offset at the predetermined inner rotor rotation angle position are collected in one place, and the envelope of the assembled offset tooth surface group is corrected for the outer rotor. It becomes the tooth tip curve of the rear tooth profile.

  Although the above-mentioned tip clearance minimization and tooth surface interference can occur even in a pump in which the inner rotor and the outer rotor have a curved tooth profile based on a trochoid curve or a cycloid curve, there is a concern that this problem may occur. When applied to a high pump, a particularly great effect can be expected.

  A pump suitable as an application object of the present invention is, for example, an internal gear pump having a small set value of the tip clearance, an inner rotor, a tooth profile including an involute curve disclosed in Patent Document 1, or the above Patent Document An internal gear pump having a tooth profile created by the method of No. 2 and having an outer rotor having a tooth profile created by the method of Patent Document 3 mentioned above.

  In addition, since it is difficult to distinguish the one side and the other side of the pump rotor, the tooth tips of the outer rotor are symmetric so that the direction of the assembly does not occur in order to prevent assembly errors.

  In the internal gear pump in which the tooth profile of the outer rotor is created by such a method, a desired interdental gap is secured between the rotors at a location excluding the meshing portion between the inner rotor and the outer rotor. The inter-tooth gap does not become zero even if the maximum machining error occurs within the allowable range of the rotor. If the machining error of the rotor is ignored (assumed to be zero), the size will correspond to the offset amount of the inner rotor. If there is a machining error in the rotor, the machining error will be subtracted from the offset value of the inner rotor. Become. The present invention also provides its internal gear pump.

  In the internal gear pump in which the tooth profile of the outer rotor is created by the method of the present invention, the inter-tooth gap is reliably ensured between the inner rotor and the outer rotor even during actual use.

  For this reason, the tip clearance when using the pump is different from the design value, and inevitable machining errors occur in the manufacturing process. Absent.

An end view showing an example of the internal gear pump of the present invention with the cover of the housing removed (A): Explanatory drawing of the method of creating the tooth profile of the inner rotor of FIG. 1 using a creation circle with a constant diameter, (b): Image diagram showing the movement state of the center of the creation circle with a constant diameter Illustration of how to create outer rotor tooth profile curve (A)-(i): The figure which shows the change of the butt | matching state of a tooth surface when an inner rotor and an outer rotor are meshed | engaged and rotated. Illustration of tooth profile creation method for outer rotor

  Embodiments of a tooth profile generating method and an internal gear pump according to the present invention will be described below with reference to FIGS. 1 to 5 of the accompanying drawings.

The internal gear pump 1 shown in FIG. 1 comprises a pump rotor 4 by combining an inner rotor 2 having n teeth and an outer rotor 3 having (n + 1) teeth in an eccentric arrangement. It is configured to be housed in the rotor chamber 6 of the housing 5. Figure O _I is the inner rotor center, O _O the outer rotor center, e is, represents the eccentricity of the inner rotor 2 and the outer rotor 3. A suction port 7 and a discharge port 8 are formed on the end surface of the rotor chamber 6.

  The inner rotor 2 of the illustrated pump 1 has a tooth profile in which the tooth tip and the tooth bottom are connected by an involute curve, or a tooth profile created by the method of Patent Document 2 (Method I below).

  As the tooth profile formed by an involute curve between the tooth tip and the tooth bottom, one using a cycloid curve for the tooth tip and the tooth bottom, or one obtained by replacing the tooth tip with an arbitrary R curve may be considered.

  Method I uses a reference circle A concentric with the inner rotor, a tooth creation circle B, and a tooth creation circle C. The creation circles B and C are circles in which a point j on the circumference passes an intersection (reference point J) of the reference circle A and the Y axis.

In this method I, as shown in FIGS. 2 (a) and 2 (b), the creation circle B of the tooth tip and the creation circle C of the tooth bottom are moved based on the following conditions (1) to (3), A locus curve drawn by the point j on the generating circles B and C that overlaps the reference point J on the reference circle A concentric with the inner rotor center O _I is drawn from the reference circle center O _I to the tooth tip vertex T _T or the tooth root vertex. addendum curve of the tooth profile drawn to form a symmetrical shape with respect to the straight line L _2, L ₃ leading to T _B, formed with at least one of the tooth bottom curved.

-Movement conditions of creation circles B and C (1)-(3)-
(1) The creation circles B and C are arranged so that the point j on the creation circle overlaps the reference point J on the reference circle A. At this time, the positions where the creation circle centers pa and pb are located are set as the movement start points. While the creation circles B and C are rotated from the movement start points Spa and Spb at a constant angular velocity, the creation circle centers are moved around the creation circles AC ₁ and AC until the creation circle centers pa and pb reach the movement end points Lpa and Lpb. Move along ₂ . The movement end points Lpa and Lpb are positions where the point j on the generating circles B and C reaches the tooth top vertex T _T or the tooth bottom vertex T _B. Based on this condition (1), the locus curve drawn by the point j on the generating circles B and C becomes a tooth profile.

(2) The movement curves AC ₁ , AC ₂ have a reference radial direction distance from the inner rotor center O _I to the generating circle centers pa, pb, and tooth tips from the movement start points Spa, Spb to the movement end points Lpa, Lpb. The distance is increased for the curve 2a, and the distance is decreased for the root curve 2b.

As a result, the movement curves AC ₁ and AC _{2 become an} upward-sloping slope curve in FIG. 2A on the tooth tip side and a downward-sloping slope curve on the tooth bottom side, and accordingly the locus drawn by the point j. Draws a smooth tooth tip and root.

(3) the addendum vertex T _T or tooth root apex T _B is in the radial direction of the reference circle A, creating a circle B in moving start point to the distance R _O between moving start point Spa and the reference circle center O _I of the created circle B The distance from the reference circle center O _I exceeds the length obtained by adding the radius of. Or, it is close to the reference circle center O _I beyond the length obtained by subtracting the radius of creation circle C in moving start point of the distance r _O between moving start point Spb and the reference circle center O _I of the creation circle C.

  Under this condition, the tooth height of the tooth drawn by the locus curve of the point j becomes higher than the tooth profile of the cycloid curve drawn by the rolling circle rolling on the basic circle.

  The creation circles B and C are either a circle that moves from the movement start point to the movement end point while keeping the diameters Bd and Cd constant, or a circle that moves from the movement start point to the movement end point while reducing the diameters Bd and Cd. Is selected. In the latter creation circle that causes a change in diameter during movement, the diameter at the movement end point is preferably 0.2 times or more and 1 time or less with respect to the diameter at the movement start point.

Creation circle center pa, pb moving start point Spa of, Spb is being placed in FIGS. 2 (a) in on the straight line _{L 1,} sometimes the straight line _{L 1} is disposed in the moving forward of the creation circle.

Further, the movement end points Lpa and Lpb of the creation circle centers pa and pb may be set at positions shifted from the straight lines L ₂ and L ₃ .

As the movement curves AC ₁ and AC ₂ , the following curves and sine functions are used in which the change rate ΔR ′ of the distance from the inner rotor center O _I to the generating circle centers pa and pb is 0 at the movement end points Lpa and Lpb. These curves are used.

  For example, the reference circular radial direction movement amount ΔR from the movement start points Spa, Spb to the movement end points Lpa, Lpb of the creation circle centers pa, pb is a curve satisfying the following expression.

ΔR = R × sin {(π / 2) × (m / S)}
Here, R: radial movement amount of the creation circle (distance from the inner rotor center O _I to the creation circle center pa at the movement end point) − (distance from the inner rotor center O _I to the creation circle center pa at the movement start point) )
S: Number of steps (number obtained by equally dividing the movement angle θ _T or θ _B from the movement start point to the movement end point of the creation circle at equal intervals)
m: 0 → S

The moving angles θ _T and θ _B of the generating circles B and C are set in consideration of the number of teeth, the tip of the teeth, the ratio of the installation area of the root, and the like.

  The outer rotor combined with the inner rotor having the tooth profile created by the above method I creates the tooth profile by the method (method II) of Patent Document 3 using the inner rotor 2 to be combined.

In the method II, as shown in FIG. 3, the center O _I of the inner rotor 2 to be combined is placed on a circle S concentric with the outer rotor center of diameter: (2e + t), and the inner rotor center O _I is placed on the circle S. The inner rotor is rotated (1 / n) times per revolution while revolving, and the envelope of the inner rotor tooth profile curve group thus obtained becomes the tooth profile of the outer rotor.
Where n is the number of teeth of the inner rotor
e: Eccentricity of outer rotor and inner rotor
t: Tip clearance. This tip clearance is achieved by placing the center of the outer rotor and the center of the inner rotor on the eccentric shaft, and moving the center of the inner rotor along the eccentric shaft from the state where the outer rotor tooth tip and the inner rotor tooth tip are opposed to each other. The distance between the opposing outer rotor tooth tip and the inner rotor tooth tip when pressed against the outer rotor.

  The inner rotor 2 and the outer rotor 3 are combined in a predetermined eccentric arrangement, one of them is fixed in this theoretical arrangement, and the other is rotated and meshed as shown in FIG.

  In FIG. 4, the inner rotor 2 is fixed at the rotation angle positions of FIGS. 4B to 4I, and the outer rotor 3 is rotated in the direction opposite to the rotor rotation direction to engage the rotors.

In FIG. 4 (a), a meshing portion in the Y unit, also concerns minimizing or addendum interference interdental gap is a position that begins to appear in the portion other than the engaging portion Z ₁ parts in FIG . Therefore, the tooth surface of the inner rotor 2 corresponding to the interdental gap corresponding to the gap between the solid line position and the outer rotor 3 in FIG. Is offset larger than the machining error allowed for the rotor in the direction of decreasing the.

  Since the tooth tips of the inner rotor 2 and the outer rotor 3 can be overlapped in the drawing, the offset of the tooth surface of the inner rotor 2 can be performed without any problem.

  I in FIG. 5 represents the tooth surface (tooth tip curve) of the inner rotor 2 offset in FIG. 4A in correspondence with the tooth surface of the outer rotor 3.

  Next, the inner rotor 2 is rotated at an arbitrary angle while following the outer rotor 3 from the state of FIG.

  FIG. 4B shows a state where the inner rotor 2 is rotated clockwise by 5 ° from the position shown in FIG. Even at this position, in the same manner as described above, the machining error allowed for the rotor in the direction of reducing the interdental gap from the center of the inner rotor by an amount corresponding to the interdental gap to be secured between the inner rotor 2 and the outer rotor 3. Offset more than.

  FIG. 4C shows a state in which the inner rotor 2 is rotated by 10 ° from the position of FIG. 4 (d) shows the state rotated by 15 °, FIG. 4 (e) shows the state rotated by 20 °, and FIG. 4 (f) shows the state rotated by 25 °. 4 (g), FIG. 4 (h) shows the state rotated 35 °, and FIG. 4 (i) shows the state rotated 40 °.

  Even at each of these positions, the inner rotor 2 is more than the machining error allowed for the rotor in the direction of reducing the interdental gap relative to the center of the inner rotor by an amount corresponding to the interdental gap to be secured between the inner rotor 2 and the outer rotor 3. A large offset.

  5 corresponds to the offset tooth surface in FIG. 4B of the tooth surface of the inner rotor 2, and III in FIG. 5 corresponds to the tooth surface of the outer rotor 3 in FIG. 4C. Let it be expressed.

  Similarly, IV to IX in FIG. 5 also represent the offset tooth surfaces of the inner rotor at the positions in FIGS. 4D to 4I corresponding to the tooth surfaces of the outer rotor 3. The offset tooth surfaces I to IX are arranged in order according to the increase in the inner rotor rotation angle.

  As shown in FIG. 5, when the inner rotor offset tooth surfaces at each position of the inner rotor rotation angle are gathered in one place, the envelope 9 can be drawn by the gathered offset tooth face group. Therefore, the envelope 9 is used as the tooth tip curve of the outer rotor.

By creating in this way, among up to Z ₂ parts of FIG. 5 (i) from Z ₁ part of FIG. 5 (a), and ignoring the machining error of the rotor, between the inner rotor 2 and the outer rotor 3 The desired interdental gap is ensured. When there is a processing error in the inner rotor 2 and the outer rotor 3, the interdental clearance secured increases or decreases by an amount corresponding to the error.

  Even when the maximum amount of machining error occurs in the allowable range by setting the offset amount at each position of the inner rotor rotation angle of the inner rotor 2 larger than the machining error allowed in the rotor, the inner rotor Interference at positions other than the meshing part of the outer rotor is prevented.

  Depending on the application of the pump, it may be preferable that the interdental gap at a position other than the meshing portion of the pump rotor is made somewhat large in order to suppress a sudden change in the pressure in the chamber accompanying the rotation of the rotor.

  Further, the interference between the tooth tips of the inner rotor and the outer rotor hinders smooth driving of the pump and promotes wear of the tooth surface.

  In addition, the tooth tip of the outer rotor is made symmetrical by reversing the tooth tip shape of the created half tooth and transferring it to the remaining half tooth.

According to the above method I, the diameter of the reference circle A: 32.900 mm, the half tooth angle from the root to the tip (movement angle θ _T , θ _B from the movement start point to the movement end point of the creation circle): 22.5 °, Creation circle B diameter Bd: 2.0563 mm, creation circle C diameter Cd: 2.0563 mm, creation circle B radial movement: 0.0288 mm, creation circle C radial movement: 1.7266 mm, creation circle Number of steps of movement of B and C S: 60 each, creation circle B, C created a tooth profile with no change in diameter during movement Large diameter: 37.07 mm, Small diameter: 25.43 mm Number of teeth: 8 inner The rotor was designed.

  Further, using the inner rotor, the above-mentioned method II is performed under the conditions of the eccentric amount e: 2.76 mm and the tip clearance t: 0.02 mm, and the number of teeth having a large diameter: 42.61 mm and a small diameter: 31.57 mm: 9 Designed the outer rotor.

Next, the inner rotor and the outer rotor were combined, and the outer rotor was rotated to a position where both the rotors meshed with the inner rotor fixed. Then, Z as interdental gap 40μm between inner rotor and outer rotor occurs for up to ₂ parts, each of the inner rotor rotation angle in Fig. 4 in FIG. 4 (j) from Z ₁ part of FIGS. 4 (a) At the position, the tooth surface of the inner rotor was offset with respect to the center of the inner rotor.

  Thereafter, the offset tooth surfaces at each inner rotor rotation angle position are gathered in one place as shown in FIG. 5, and the corrected tooth profile of the outer rotor is obtained by making the envelope of the gathered offset tooth face group a tooth tip curve of the outer rotor. Actual product tooth profile).

  When the outer rotor thus obtained was combined with the inner rotor whose tooth profile was created by Method I and operated under the same conditions as in actual use, there was no interference of the tooth tips.

  Although the above description has been made by taking a pump having a specific tooth profile as an example, the present invention can also be applied to an internal gear pump having a curved tooth profile based on a trochoid curve or a cycloid curve.

DESCRIPTION OF SYMBOLS 1 Internal gear pump 2 Inner rotor 2a Tooth tip curve 2b Tooth bottom curve 3 Outer rotor 4 Pump rotor 5 Housing 6 Rotor chamber 7 Suction port 8 Discharge port 9 Inner rotor offset tooth surface envelope I-IX Inner rotor rotation angle Inner rotor offset tooth surface O _I inner rotor center at each position (reference circle center)
O _O Outer rotor center A Reference circle Ad Reference circle diameter B Tooth tip creation circle C Tooth root creation circle Bd, Cd Creation circle diameter AC ₁ , AC ₂ Creation circle center travel curve R Radial travel of creation circle moving start point Spa and the reference circle center _O distance between _{I r O} creation circle C a distance theta _T between the moving start point Spb and the reference circle center _{O I} of Ro creation circle B, theta of _B creating circular movement angle J on the base circle of Reference point j Point to draw trajectory curve T _T Tip top vertex T _B Bottom vertex L ₁ Straight line connecting inner rotor center and reference point J ₂ Straight line connecting inner rotor center and tooth tip
L ₃ straight line connecting the inner rotor center and the tooth bottom
pa, pb Creation circle center Spa, Spb Creation circle movement start point Lpa, Lpb Creation circle movement end point S Number of steps e Eccentricity of inner rotor center and outer rotor center t Tip clearance

Claims (3)

  The inner rotor (2) having n teeth of the internal gear pump and the outer rotor (3) having (n + 1) teeth having a correction tooth shape are meshed with each other at a predetermined eccentric arrangement position. 2) The tooth surface to be secured between the outer rotor (3) and the outer rotor (3) at a place other than the meshing portion with the outer rotor (3) and where there is a concern about minimization of tooth gaps or tooth interference. The offset tooth surface group is formed by gathering the offset tooth surfaces of the inner rotor obtained by repeating the offset at a predetermined inner rotor rotation angle position at one position, with a large offset to the outside corresponding to the gap between the inner rotors. The tooth profile creation method of the outer rotor which uses the envelope curve of the outer rotor as the tooth profile of the corrected tooth profile of the outer rotor The inner rotor (2) has a tooth profile formed by an involute curve between a tooth tip and a tooth bottom, or a tooth profile created by the following method I, and the outer rotor (3) is a corrected front tooth profile by the following method II. The tooth profile creation method for an outer rotor according to claim 1, wherein the tooth profile is created and the tooth profile of the outer rotor (3) of the internal gear pump is created.
Method I: Tooth tip creation circle (B) and root creation circle (C) are moved based on the following conditions (1) to (3), while the inner rotor center (O _I ) is concentric with the reference The locus curve drawn by the point (j) on the generating circle (B, C) that overlaps the reference point (J) on the circle (A) is drawn from the center of the reference circle (O _I ) to the tooth tip vertex (T _T ) or tooth The tooth tip curve or the root curve of the tooth profile is drawn so as to have a symmetrical shape with respect to the straight line (L ₂ , L ₃ ) leading to the bottom vertex (T _B ).
-Movement conditions for creation circles B and C-
(1) The creation circles (B, C) are arranged so that the points (j) on the creation circles overlap the reference point (J) on the reference circle (A). At this time, the creation circle center (pa , Pb) with a certain position as the movement start point, the creation circle center (pa, pb) rotates from the movement start point (Spa, Spb) at a constant angular velocity to the creation end point (Lpa, Lpb). The center of the creation circle is moved along the movement curve (AC ₁ , AC ₂ ) of the center until it reaches ().
(2) The movement curves (AC ₁ , AC ₂ ) move from the movement start point (Spa, Spb) a reference radial direction distance from the inner rotor center (O _I ) to the creation circle center (pa, pb). To the end point (Lpa, Lpb), the distance is increased for the tip curve (2a), and the distance is decreased for the root curve (2b).
(3) The tip of the tooth tip (T _T ) or the bottom of the tooth tip (T _B ) is between the movement start point (Spa) of the creation circle (B) and the center of the reference circle (O _I ) in the radial direction of the reference circle (A). The distance from the reference circle center (O _I ) exceeds the length obtained by adding the radius of the creation circle (B) at the movement start point to the distance (R _O ). Alternatively, the reference circle exceeds the length obtained by subtracting the radius of the creation circle (C) at the movement start point from the distance (r _O ) between the movement start point (Spb) of the creation circle (C) and the reference circle center (O _I ). Approaching the center (O _I ).
Method II: The inner rotor center (O _I ) makes one revolution on a circle with a diameter (2e + t) centered on the outer rotor center, and the inner rotor (2) rotates (1 / n) times during this time. The envelope of the tooth profile curve group of the inner rotor is used as the tooth profile of the outer rotor.
Where n is the number of teeth of the inner rotor
e: Eccentricity of outer rotor and inner rotor
t: Tip clearance An inner rotor number of n teeth (2), the outer rotor (3) pumps in combination with the eccentric arrangement of the rotor of the number of teeth having thus created have been teeth in Method towards according to claim 2 (n + 1) ( 4)
An inscribed structure configured such that a gap corresponding to the offset amount of the inner rotor is generated between the inner rotor (2) and the outer rotor (3) at a location other than the meshing portion during actual pump operation. Gear pump.

Images