JP2006063883A - Internal gear type pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal gear type pump increasing volume efficiency by suppressing leak from a sliding clearance part between an internal gear rotor and a pump case storing the same. <P>SOLUTION: An inner circumference edge 7a of a delivery port 7 provided on a pump case 5 with corresponding to a pump chamber 4 formed between an inner rotor 1 and an outer rotor 2 is arranged in an inner rotor outer diameter side of locus of a tooth bottom of the inner rotor 1 to increase seal width T of a sliding clearance part. Consequently, quantity of liquid leaking out of the delivery port 7 to an intake port 6 and an inner diameter 13 side through the sliding clearance part is reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal gear pump in which volumetric efficiency (discharge efficiency) is improved by reducing liquid leakage from a sliding clearance portion of an internal gear rotor.

  Among known internal gear pumps, for example, there are those disclosed in Patent Documents 1 and 2 below. These internal gear pumps employ an internal gear rotor (pump rotor) in which an inner rotor and an outer rotor having a single tooth difference are combined.

  A conventional example of an internal gear pump having such an internal gear rotor is shown in FIG. The inner rotor 1 and the outer rotor 2 constituting the internal gear rotor 3 are combined in an eccentric arrangement. A suction port 6 and a discharge port 7 corresponding to a pump chamber 4 formed between the inner rotor 1 and the outer rotor 2 are provided in the pump case 5.

The suction port 6 and the discharge port 7 have an inner peripheral edge (periphery on the rotor center side) 6a, 7a in an arc substantially overlapping the locus of the bottom of the inner rotor 1, and an outer peripheral edge (periphery on the rotor outer diameter side) 6b. , 7b are formed by arcs substantially overlapping with the locus of the tooth bottom of the outer rotor 2. The arc radii of the inner peripheral edges 6a and 7a of both ports are R1 _INN = R1 _OUT , and the arc radii of the outer peripheral edges 6b and 7b are R2 _INN = R2 _OUT , and the width of the suction port 6 and the discharge port 7 (R2 _INN − R1 _INN and _{R2 OUT -R1} OUT) are equal.

  In this internal gear type pump, the seal of the pump chamber 4 that has shifted to the discharge stroke is formed by a sliding clearance between the end surface of the internal gear rotor 3 and the inner surface of the pump case 5. The seal width of the sliding clearance portion is indicated by T.

  The seal width T becomes narrower as the size of the internal gear rotor 3 becomes smaller, and accordingly, the amount of liquid leakage from the sliding clearance portion increases and the volumetric efficiency of the pump decreases.

  Internal gear pumps are widely used as automobile oil pumps, and in such applications, there is a strong demand for downsizing. However, if the internal gear rotor is downsized, the amount of liquid leakage from the sliding clearance portion increases as described above, and the volumetric efficiency of the pump decreases.

Although Patent Documents 1 and 2 suppress a decrease in discharge efficiency due to cavitation, the improvement measures described in these documents suppress liquid leakage from the sliding clearance portion of the internal gear rotor. It was not always easy to do.
JP 2003-214356 A JP 2003-227474 A

  This invention makes it possible to increase the volumetric efficiency of the pump by suppressing liquid leakage from the sliding clearance portion of the end face of the internal gear rotor, or to reduce the size of the pump while maintaining the same discharge rate as before. The challenge is to make it uniform.

In order to solve the above problems, in the present invention, an internal gear pump in which the discharge port side seal area between the inner rotor and the pump case is larger than the suction port side seal area,
As a specific form thereof, the inner peripheral edge of the discharge port provided in the pump case corresponding to the pump chamber formed between the inner rotor and the outer rotor is positioned closer to the outer diameter side of the inner rotor than the locus of the bottom of the inner rotor. An internal gear pump in which the discharge port side seal area between the inner rotor and the pump case is larger than the suction port side seal area,
An internal gear pump in which the inner peripheral edge of the discharge port provided in the pump case corresponding to the pump chamber formed between the inner rotor and the outer rotor is arranged on the outer diameter side of the inner rotor from the locus of the bottom of the inner rotor. When,
The inner peripheral edge of the discharge port and the inner peripheral edge of the suction port provided in the pump case are arcs concentric with the center of the inner rotor, the arc radius of the inner peripheral edge of the suction port is R1 _INN , and the arc radius of the inner peripheral edge of the discharge port is R1 _OUT An internal gear pump that satisfies the condition of R1 _OUT > R1 _INN is provided.

  In these pumps, the inner peripheral edge of the suction port may be arranged closer to the center side of the inner rotor than the locus of the bottom of the inner rotor, and an internal gear pump having such an arrangement is also provided.

Further, in addition, an internal gear pump in which the outer peripheral edge of the discharge port is disposed closer to the outer rotor center side than the locus of the bottom of the outer rotor,
As a specific form, the inner peripheral edge of the discharge port and the inner peripheral edge of the suction port provided in the pump case are concentric with the center of the inner rotor, the outer peripheral edge of the discharge port, and the suction provided in the pump case corresponding to the pump chamber. The outer peripheral edge of each port is an arc concentric with the center of the outer rotor, the arc radius of the inner peripheral edge of the suction port is R1 _INN , the arc radius of the inner peripheral edge of the discharge port is R1 _OUT , and the arc radius of the outer peripheral edge of the suction port is R2 _INN, the arc radius of the outer peripheral edge of the discharge port as _{R2 OUT,} also provides R1 _{OUT> R1 INN} and _{R2 INN> R2 OUT} internal gear pump which satisfy the conditions of the.

  Furthermore, the inner rotor center and the outer rotor are combined with the outer rotor by combining the inner rotor having a tooth profile formed by a hypocycloid curve, a meshing portion with the outer rotor, an involute curve, and a tooth tip portion having an arbitrary curve. An internal gear rotor (hereinafter referred to as a specially shaped rotor) in which the center eccentricity e is larger than the eccentricity of a trochoid or cycloid internal gear rotor having the same outer diameter, rotor thickness and number of teeth, In addition, an internal gear pump in which the above-described configuration is added is also provided. The trochoidal internal gear rotor means that the tooth profile is formed only by a trochoid curve, and the cycloid internal gear rotor means that the tooth profile is formed only by a cycloid curve.

  The outer rotor employed in the above-mentioned special-shaped rotor is formed by revolving the inner rotor center around the center of the outer rotor by drawing a circle with a diameter (2e + t) while the inner rotor center makes one round of the circle. The envelope of the inner rotor tooth profile curve group produced by rotating / n times is defined as the tooth profile.

Where, e: the amount of eccentricity between the center of the inner rotor and the center of the outer rotor
t: Maximum clearance between outer rotor and inner rotor pressed against it
n: Number of teeth of inner rotor

  If the inner peripheral edge of the discharge port is arranged on the outer diameter side of the inner rotor than the locus of the root of the inner rotor, the distance from the inner peripheral edge of the discharge port to the suction port is increased, and the seal width is increased by the sliding clearance portion between them. This reduces the amount of liquid leakage from the sliding clearance.

  Since the amount of liquid leakage from the sliding clearance portion increases in proportion to the pressure difference between the suction port and the discharge port, the effect of the present invention is particularly remarkable in a pump in which the pressure difference is large.

  In addition, a pump in which the inner peripheral edge of the suction port is arranged closer to the inner rotor center side than the locus of the root of the inner rotor can be expected to reduce the driving torque by reducing the sliding area of the rotor.

  The liquid leakage occurs mainly because the liquid pumped up by the pump escapes from the discharge port to the inner diameter 13 (see FIG. 1) through the sliding clearance between the inner rotor and the pump case. In the case of a pump in which the outlet passage 8 from the discharge port 7 is provided by cutting out the sliding surface with the outer periphery of the outer rotor as shown in FIG. It is conceivable that the liquid leaked from the sliding clearance portion of the end face of the outer rotor leaks from the notched portion, and in such a pump, the outer peripheral edge of the discharge port 7 is more than the locus of the outer rotor tooth bottom. It is also effective to increase the seal width of the sliding clearance portion on the outer rotor side by disposing it on the center side.

  The internal gear pump adopting the above-mentioned specially shaped rotor increases the eccentric amount e of the inner rotor and outer rotor than the conventional pump to increase the discharge amount of the pump. What added the said structure which expands a width | variety becomes a thing with better discharge performance.

  Embodiments of the present invention will be described below with reference to FIGS. 1 to 6 of the accompanying drawings. The illustrated internal gear type pump is configured by housing the internal gear rotor 3 in a pump case 5.

  The internal gear rotor 3 uses a combination of an inner rotor 1 and an outer rotor 2 having one tooth difference in an eccentric arrangement, as in the conventional pump of FIG. The pump case 5 is provided with a suction port 6 and a discharge port 7 corresponding to a pump chamber 4 formed between the inner rotor 1 and the outer rotor 2.

  As shown in FIG. 2, the pump case 5 includes a main body 5a and a cover 5b. In FIG. 2, the suction port 6 and the discharge port 7 are provided on both the inner surface of the main body 5a and the inner surface of the cover 5b (both surfaces that face the rotor end surface), but may be provided only on the inner surface of the main body 5a. is there.

As shown in FIG. 3, the suction port 6 has an inner peripheral edge 6a formed with an arc having a radius R1 _INN and an outer peripheral edge 6b formed with an arc having a radius R2 _INN , while the discharge port 7 has an inner peripheral edge 7a. in the arc of radius _{R1 OUT,} to form respectively the outer peripheral edge 7b in arc having a radius _{R2 OUT.}

The arc radii R2 _OUT and R2 _INN are equal to each other, and the outer peripheral edge 6b of the suction port and the outer peripheral edge 7b of the discharge port are in positions that substantially overlap the locus of the tooth bottom of the outer rotor 2. On the other hand, the arc radius R1 _OUT is larger than R1 _INN . The inner peripheral edge 6a of the suction port having the radius R1 _INN is substantially overlapped with the locus of the root of the inner rotor 1, and the inner peripheral edge 7a of the discharge port having the radius R2 _INN is closer to the inner rotor 1 than the locus of the root of the inner rotor 1. It is on the outer diameter side. Accordingly, the width of the discharge port 7 is narrower than the width of the suction port 6, and the seal width T of the sliding clearance portion between the end face of the inner rotor 1 and the pump case 5 becomes larger than before, and the liquid from this portion Leakage is reduced.

  When the inner peripheral edge 6a of the suction port 6 is arranged closer to the inner rotor center side than the locus of the bottom of the inner rotor 1 as shown by a chain line in FIG. The inner peripheral edge 7a of the discharge port 7 may be arranged at a position where the decrease in the seal width can be offset by an increase in the seal width on the discharge port side, or on the rotor outer diameter side.

  Next, the principal part of an example of the inner rotor which comprises the above-mentioned special shape rotor is expanded and shown in FIG. The inner rotor 11 is proposed by the present applicant in Japanese Patent Application No. 2003-274844, wherein the tooth gap 11c is a hypocycloid curve, the meshing portion 11b with the outer rotor is an involute curve, and the tooth tip portion Arbitrary curve that smoothly connects 11a to the meshing part 11b (for example, an epicycloid curve that is smoothly connected to the involute curve of the meshing part 11b is preferable, but an arc curve or a curve that forms part of an ellipse may also be used) Each is made up of.

  The hypocycloid curve of the tooth gap 11c is formed by a locus of one point of the rolling circle 9 at that time, when the rolling circle 9 having the diameter d rolls in contact with the base circle 10 having the diameter D1 without slipping. The diameter D of the base circle (pitch circle) 20 of the involute curve of the meshing part 11b is smaller than the diameter D1 of the base circle 10 of the hypocycloid curve. The base circles 10 and 20 are circles having a center at the same position.

  In this tooth profile, the position of the surface of the meshing portion 11b is set first, and the surface of the hypocycloid curve of the tooth groove 11c with respect to that surface (involute curve) is preferably Q point with an inclination angle α of about 65 ° to 85 °. The diameter D1 of the basic circle 10 and the diameter d of the rolling circle 9 of the hypocycloid curve are determined so as to be connected to each other.

  The aforementioned inclination angle α is a line perpendicular to the radial line L passing through the center (not shown) of the basic circles 10 and 20 and the connection point Q (centering on the center of the inner rotor passing through the connection point Q). It is an inclination angle with reference to a tangent at a circle connection point Q) (0 °).

  If the diameter of the inner rotor 1, the number of teeth, the tooth height, the inter-pitch pitch, the position of the surface of the meshing portion 11b, and the inclination angle α of the surface (involute curve) at the connection point Q are determined, the hypocycloid curve forming the tooth groove 11c. Appropriate sizes of the diameter D1 of the basic circle 10 and the diameter d of the rolling circle 9 are obtained.

  The tooth profile of the outer rotor 12 (see FIG. 5) combined with the inner rotor 11 having such a tooth profile is created by the following method.

  As shown in FIG. 6, the center Oi of the inner rotor 11 is revolved by drawing a circle S having a diameter (2e + t) around the center Oo of the outer rotor (t: the inner rotor 11 pressed against the outer rotor 12 and the outer rotor 12. The maximum gap between the two).

  Further, while the center Oi of the inner rotor 11 makes one round of the circle S, the inner rotor 11 rotates by 1 / n (n: number of teeth of the inner rotor). If it carries out like this, the tooth profile curve of the inner rotor 11 shown with a dashed-dotted line in FIG. 6 will appear in each position of the revolution accompanying rotation of an inner rotor. The envelope of the tooth profile curve group is used as the tooth profile of the outer rotor 12. The tooth profile of the outer rotor obtained in this way is the final tooth profile, if necessary, modified so that interference does not occur in meshing rotation with the inner rotor.

  The special shape rotor described above has a degree of freedom in setting the eccentricity e between the inner rotor center and the outer rotor center, and the eccentricity e is determined based on the trochoidal internal gear rotor or cycloid having the same outer diameter, rotor thickness, and number of teeth. The pump discharge amount can be increased by setting it to be larger than the eccentric amount of a conventional pump that employs a mold internal gear rotor, and the amount of liquid leakage from the sliding clearance portion of the pump is reduced by the structure described above. Thus, it is possible to provide an internal gear pump having a superior discharge performance.

The front view which shows the principal part of embodiment of the internal gear type pump of this invention Sectional view along the line II-II in FIG. Front view of the port provided in the pump case Diagram showing inner rotor tooth profile of special shape rotor Front view of special shape rotor The figure which shows the tooth profile creation method of the outer rotor of FIG. Front view showing the main parts of a conventional internal gear pump The figure which shows the example which provided the exit passage from the discharge port in the position which cuts off the inner surface of a pump case

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 Inner rotor 2, 12 Outer rotor 3 Internal gear rotor 4 Pump chamber 5 Pump case 6 Suction port 7 Discharge port 8 Outlet passage 9 Rolling circle 10 Hypocycloid curve basic circle 20 Involute curve basic circle 11b Involute curve Formed meshing part 13

Claims (7)

  In an internal gear type pump configured by housing an internal gear rotor in which an inner rotor and an outer rotor are arranged eccentrically in a pump case, the discharge port side seal area between the inner rotor and the pump case is the suction port. An internal gear pump characterized in that it is larger than the side seal area.   The inner peripheral edge of the discharge port provided in the pump case corresponding to the pump chamber formed between the inner rotor and the outer rotor is arranged on the outer diameter side of the inner rotor from the locus of the root of the inner rotor. The internal gear pump according to claim 1. The inner peripheral edge of the discharge port and the inner peripheral edge of the suction port provided in the pump case so as to correspond to the pump chamber are arcs concentric with the center of the inner rotor, and the arc radius of the inner peripheral edge of the suction port is R1 _INN . inner peripheral edge of the arc radius as _{R1 OUT, R1 OUT> R1 INN} internal gear pump according to claim 1 or 2 condition was satisfied in the.   The internal gear pump according to any one of claims 1 to 3, wherein an inner peripheral edge of the suction port is disposed closer to an inner rotor center side than a locus of a root of the inner rotor.   The internal gear pump according to claim 1 or 2, wherein an outer peripheral edge of the discharge port is arranged closer to the outer rotor center side than a locus of a tooth bottom of the outer rotor. The inner peripheral edge of the discharge port and the inner peripheral edge of the suction port provided in the pump case corresponding to the pump chamber are arcs concentric with the center of the inner rotor, respectively, and the outer peripheral edge of the discharge port and the outer peripheral edge of the suction port are outer A circular arc concentric with the rotor center, the arc radius of the inner peripheral edge of the suction port is R1 _INN , the arc radius of the inner peripheral edge of the discharge port is R1 _OUT , the arc radius of the outer peripheral edge of the suction port is R2 _INN , and the outer peripheral edge of the discharge port The internal gear pump according to claim 5, wherein the conditions of R1 _OUT > R1 _INN and R2 _INN > R2 _OUT are satisfied, with the arc radius of R2 _OUT being R2.   Combining the inner rotor with the outer rotor, the inner rotor having a tooth profile formed with a hypocycloid curve, the meshing part with the outer rotor being an involute curve, and the tooth tip being an arbitrary curve. The internal gear rotor according to any one of claims 1 to 6, wherein an internal gear rotor having an eccentric amount e larger than an eccentric amount of a trochoid type or cycloid type internal gear rotor having the same outer diameter, rotor thickness, and number of teeth is employed. Closed gear pump.

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