JPH10205458A - Inscribed gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inscribed gear pump to optimize a design for the shapes of external and internal tooth gears, reduce a leakage amount through improvement of cutting-off ability between the suction side and the discharge side, and have high discharge amount. SOLUTION: In an inscribed gear pump wherein an internal tooth gear has the number of teeth higher than that of an external tooth gear 3 by one tooth and the addenda of two gears are brought into slide over each other on the opposite side to a part where the two gears most deeply engaged with each other, the the tooth shape of the external gear 3 is formed such that an addendum surface 3b, a bottom surface 3c and tooth surface 3d are formed in a shape where a plurality of circular arcs are smoothly and continuously combined together and the tooth shape of the internal tooth gear is a shape generated by the tooth shape of the external tooth gear 3. The curvature centers and the curvatures of radius R1-R5 of the respective circular arcs of the addendum surface 3b, the bottom surface 3c, and the tooth surface 3d so that the approximate whole of the tooth shape of the external tooth gear 3 are positioned on the envelope of a locus drawn by the tooth shapes during the generation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an internal gear pump.

[0002]

2. Description of the Related Art As a pump used in a hydraulic apparatus, there is a trochoid tooth type internal gear pump (trochoid pump) 10 as shown in FIG. The internal gear pump 10 includes a trochoid external gear 11 and an internal gear 12
And a housing (not shown) for accommodating them. The side surfaces of these two gears 11 and 12 are sealed by side plates of the housing. External gear 1
The number of teeth of 1 is set to be smaller than the number of teeth of the internal gear 12 by one tooth. When the external gear 11 rotates in the direction of arrow A, the internal gear 12 is driven to rotate. And discharges the fluid to the discharge port 14.

The internal gear pump 10 has a suction or discharge operation performed in a long section almost equal to half a circumference as compared with other gear pumps such as an internal gear pump and an external gear pump using a partition plate. The volume change of the space holding the fluid is not abrupt, but is performed continuously and slowly,
It has the characteristic of low noise. It is used for many pumps such as a hydraulic pump for engine lubrication of a vehicle, a hydraulic pump for an automatic transmission, and a fuel supply pump.

[0004]

However, in the conventional internal gear type pump, the suction port 13 and the discharge port 14 are not provided.
And the number of teeth 11a and 12a for closing the gap between the suction port 13 and the discharge port 14 is small (in most cases, one tooth). A large amount of fluid leaks from the high pressure side) to the suction side (low pressure side). For this reason, there is a problem that the discharge amount is reduced and efficiency is low.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made to optimize the design of the tooth profile of an external gear and an internal gear, to increase the shut-off property between the suction side and the discharge side, and to reduce the amount of leakage. And to provide an internal gear pump with a high discharge rate.

[0006]

According to the present invention, there is provided an internal gear rotatably mounted in a housing, and external teeth eccentrically disposed in the internal gear. And an internal gear pump in which both gears rotate while meshing with each other, and suck and discharge fluid between the two gears, wherein the internal gear has one more tooth than the external gear. In a pump of the type in which the tips of the two gears slide on opposite sides of the part where the two gears mesh deepest with each other, the tooth profile of one of the gears smoothes a plurality of arcs. The tooth shape of the other gear is a shape created by the tooth shape of the one gear, and substantially the entire tooth surface of the one gear is the tooth shape of the gear at the time of creation. The one tooth so that it is located on the envelope of the locus The center of curvature and the curvature radius each arc of the tooth profile is characterized by being respectively set.

According to a second aspect of the present invention, the tooth surface of the external gear is set closer to the gear center than the pitch circle of the external gear. Claim 3 is characterized in that the one gear is the external gear and the other gear is an internal gear. The tooth profile of the external gear of the internal gear pump is formed by smoothly and continuously combining a plurality of arcs, the tooth profile of the internal gear is formed by the tooth profile of the external gear, and the tooth profile of the external gear is By setting the center of curvature and the radius of curvature of each arc of the tooth profile of the external gear so that substantially the entire tooth surface is located on the envelope of the locus drawn by the tooth profile of the gear at the time of creation, the suction side of the pump and the discharge It is possible to reduce the gap between the tooth tips to be closed to the side. Furthermore, by making the tooth profile of the external gear into a shape in which a plurality of arcs are smoothly and continuously combined, it is easy to increase the number of teeth, and it is possible to use a plurality of teeth for the cutoff between the suction port and the discharge port. It is possible to make the tip space of the plurality of closing teeth the same. As a result, the closing performance is improved, and the discharge amount is increased.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below by way of examples. In FIG. 1, an internal gear pump 1
Has an internal gear 2 and an external gear 3, and the external gear 3 is eccentrically arranged in the internal gear 2. The internal gear 2 is
For example, the external gear 3 has 13 teeth 2a, and the external gear 3 has 12 teeth 3a, one tooth smaller than the internal gear 2. The internal gear 2 is rotatably housed in a housing (not shown), and the side surfaces of the two gears 2 and 3 are sealed by side plates of the housing. In addition, a suction port 4 and a discharge port 5 are formed on one side plate as shown by a two-dot chain line. In addition, the rotating shaft 6 is fixed to the center of the external gear 3. The rotating shaft 6 is driven by external power, and the external gear 3 is rotated in the direction of arrow A to be used as the input shaft of the internal gear pump 1.

The external gear 3 is arranged eccentrically with respect to the internal gear 2, and both gears mesh with each other and rotate in the same direction. The tip surfaces 2b and 3b of the two gears 2 and 3 are slidable with a slight gap δ at a position Y0 opposite to the portion X where the teeth 2a and 3a mesh most deeply. In addition, a plurality of, for example, three teeth 2a and 3a are closed between the suction port 4 and the discharge port 5.

Then, a range of a predetermined rotation angle θ is set on both front and rear sides in the rotation direction with respect to the center (Y0 position) tooth among the three cut-off teeth of the internal gear 2 and the external gear 3 respectively. In this embodiment, the tooth gap between each tooth 2a of the internal gear 2 and each tooth 3a of the external gear 3 is set to be the same at a small gap δ, for example, at an interval of 50 μm. Is set. The range of the rotation angle θ where the gap δ is narrow is preferably long, but need not be too long. Therefore, in this embodiment,
As an example, it is set to about 2.5 teeth (rotation angle θ is about 69 °). The range in which the gap δ is provided is at least a cutoff range for shutting off the suction port 4 and the discharge port 5 from Y-1 to Y + 1.
It should be within the range of 3 teeth, but Y-2 to Y
Set to the range of +2.

First, the shape of the teeth 3a of the external gear 3 will be described. As shown in FIG. 2, the teeth 3a of the external gear 3
Is composed of a tooth tip surface 3b, a tooth bottom surface 3c, and a tooth surface 3d. The tooth surface 3d has a central surface 3e, a root surface 3f, and a tooth end surface 3g.
Consists of The central surface 3e of the tooth surface 3d has a large radius R
The tooth bottom surface 3c is formed of a part of a cylindrical surface having a radius R2, and the tooth tip surface 3b is formed of a part of a cylindrical surface having a radius R4. The tooth root surface 3f is composed of a part of a cylindrical surface having a radius R3 inscribed in the central portion surface 3e and the tooth bottom surface 3c, and the tooth tip surface 3g is circumscribed to the tooth tip surface 3b and is in contact with the central surface 3e.
e and a part of a cylindrical surface having a radius R5 inscribed in e. Thus, the tooth shape of the tooth 3a is a curved surface in which the tooth surface 3d smoothly continues from the tooth tip surface 3b to the tooth bottom surface 3c.

When the tooth surface 3d of the external gear 3 is formed, the radius R1 forming the surface 3e at the center of the tooth surface 3d is a value determined by the basic specifications of the module and the like, and the remainder depends on the pressure angle. It cannot be changed significantly. On the other hand, tooth surface 3
The radius R3 forming f is formed by the central surface 3e and the tooth bottom surface 3c.
Are set so as to be in contact (smoothly continuous) with the arc of each of the circle radii R1 and R2, and the value of the radius R3 can be arbitrarily changed. Therefore, the gap δ is secured by changing the radii R2 and R3 without changing the radius R1. The radius R2 of the tooth bottom surface 3c and the tooth root surface 3
By setting a large number of radii of f, the accuracy of the gap δ can be improved. For example, although the tooth root surface 3f is a part of one cylindrical surface of radius R3, a part of cylindrical surfaces of a plurality of different radii (for example, R3a, R3b, R3c, etc.) is smoothly and continuously combined. May be formed. However, it is sufficient to adjust the two radii R2 and R3.

The tooth shape of the tooth 3a is symmetrical, and the tooth surfaces 3d on both sides have the same shape. Thus, the tooth profile of the teeth 3a of the external gear 3 is determined. By the way, the radius R1
For example, assuming that the tooth height of the tooth 3a is H, R1 = 4.5H, R2 = 1.3H, R3 = 0.6H, R
4 = 4H and R5 = 0.48H. By the way, the internal gear pump is different from the internal gear 2 and the external gear 3 in terms of pump performance.
It is preferable to provide a slight gap between the tooth top surface 3b of the external gear 3 and the tooth bottom surface 2c of the internal gear 2 in a state where the gears are meshed most deeply. Therefore, the external gear 3 is set so that the addendum circle (the addendum surface 3b) is located slightly inside (center side) of the pitch circle 3h, and as shown in FIG. The circle 2h is set so as to be located slightly outside the root circle (the root 2c).

Next, the tooth profile of the internal gear 2 is created by the tooth profile of the external gear 3. As shown in FIG.
It has the same shape as the external gear 3, and the internal gear 2 is created by the cutter 7. In this case, each of the five teeth 3a of the external gear 3 and the internal gear 2 in the range of the rotation angle 2θ.
The gap δ between the tooth surface 2g and the tooth tip surface 2b of the tooth surface 2d of the internal gear 2 is determined by the shape of the tooth tip surface 2b. The shape is determined by the shape of the root surface 3c (from the start position A of the root surface 3f in FIG. 4 to the center position B of the root surface 3c). Therefore, the center of curvature of each of the arcs R1 to R5 of the tooth surface 3d and the center of curvature of the tooth surface 3d so that substantially the entire tooth surface 3d of the external gear 3 is located on the envelope of the locus drawn by the tooth profile of the gear 3 when the internal gear 2 is created. Set the radius of curvature.
Then, the shapes (ie, radii) of the blade surfaces 7f and 7c of the cutter 7 corresponding to the tooth root surface 3f and the tooth bottom surface 3c of the external gear 3 are adjusted to adjust the internal gear 2 as shown by a two-dot chain line. Tooth surface 2d
To the shape when the tooth surface 3d of the external gear 3 moves away with the gap δ. That is, the blade surface 7 of the cutter 7
This adjustment is possible because f, 7c and the tooth surfaces 2b, 2g and 3b, 3g are independent. Thereby, the gap δ between the external gear 3 and the internal gear 2 when the tooth surfaces 3d of the external gear 3 and the internal gear 2 move away from the corresponding tooth surfaces 2d can be made equal within the range of the rotation angle θ.

The operation will be described below. FIG. 5 shows the movement from the beginning of meshing of these teeth 2a and 3a to the end of meshing at a portion X where the teeth 2a of the internal gear 2 and the teeth 3a of the external gear 3 mesh most deeply. Is stopped, the external gear 3 is rotated in the direction of arrow A. In FIG. 5, the teeth 3a of the external gear 3
Begin to mesh with a gap δ from the position of the apex B of the tooth tip surface 2b of the tooth 2a of the internal gear 2 as shown by the curves I to IV indicated by the solid line, and from the position beyond the position of the point A The meshes are meshed with the bottom surface 2c as shown by the solid lines IV to VI, and from the tooth bottom surface 2c to the point A of the next tooth 2a are separated by backlash as shown by the dashed lines VII and VIII. This backlash can be secured by creating the internal teeth with the external teeth having a tooth thickness larger by the backlash. Further, the tooth 3a is
Curves IX to X indicated by dashed lines up to the vertex B of the tooth tip surface 2b of FIG.
As shown by, it leaves the tooth surface 2d with a gap δ.
The trajectory of the tooth tip surface 3b of the tooth 3a at this time is indicated by a chain line XV. Thereby, the gap between each of the five teeth 2a and the teeth 3a in the range of 2θ shown in FIG. 1 becomes a constant gap δ.

The clearance δ is extremely narrow, 50 μm, and the gap between the suction port 4 and the discharge port 5 is completely closed by a plurality of teeth (three in this embodiment) 2a. To improve. As a result, leakage of the pressure fluid from the discharge side to the suction side is significantly reduced, and the discharge amount is increased.

[0017]

As described above, according to the present invention, the tooth profile of the external gear of the internal gear pump is formed by smoothly and continuously combining a plurality of arcs, and the tooth profile of the internal gear wheel is changed. The center of curvature of each arc of the tooth profile of the external gear so that it is shaped by the tooth profile of the external gear and that substantially the entire tooth surface of the external gear is located on the envelope of the locus drawn by the tooth profile of the gear at the time of generation. By setting the radius of curvature and the radius of curvature, respectively, it is possible to reduce the gap between the tooth tips that shuts off the suction side and the discharge side of the pump, and it is possible to set a large number of teeth. A plurality of teeth can be used for the cutoff, and the interval between the tips of these teeth can be the same, the cutoff performance is improved, the discharge amount is increased, and the efficiency of the pump is improved. improves.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a relationship between an internal gear and an external gear of an internal gear pump according to the present invention.

FIG. 2 is an explanatory diagram of a tooth profile of the external gear shown in FIG. 1;

FIG. 3 is an explanatory diagram of a tooth profile of the internal gear of FIG. 1;

FIG. 4 is an explanatory diagram in a case where a tooth profile of an internal gear is created based on a tooth profile of an external gear in FIG. 2;

FIG. 5 is an explanatory diagram of meshing between the internal gear and the external gear of FIG. 1;

FIG. 6 is an explanatory diagram showing a relationship between an internal gear and an external gear of a conventional trochoid pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal gear pump 2 Internal gear 3 External gear 2a, 3a Tooth 2b, 3b Tooth surface 2c, 3c Bottom surface 2d, 3d Tooth surface 2h, 3h Pitch circle

Claims (3)

[Claims] An internal gear rotatably mounted in a housing, and an external gear disposed eccentrically in the internal gear, wherein both gears rotate while meshing with each other. An internal gear pump that sucks and discharges fluid between the internal gears, wherein the internal gear has one more tooth than the external gear, and the two gears are on opposite sides of a portion where the two gears mesh deepest with each other. In a pump of the type in which the tooth tips of both gears slide with each other, the tooth shape of one of the gears is a shape formed by smoothly and continuously combining a plurality of arcs, and the tooth shape of the other gear is The tooth profile of the one gear is a shape created by the tooth profile of the one gear, and substantially the entire tooth surface of the one gear is located on the envelope of the locus drawn by the tooth profile of the gear at the time of creation. The center of curvature and radius of curvature of each arc are set respectively. Internal gear pump according to claim Rukoto. 2. The internal gear pump according to claim 1, wherein the tooth surface of the external gear is set closer to the center of the gear than the pitch circle of the external gear. 3. The one gear is the external gear,
The internal gear pump according to claim 1, wherein the other gear is an internal gear.