JP4680496B2 - Rotating positive displacement pump and gear for rotary positive displacement pump provided with meshing gear that does not cause confinement - Google Patents

Description

  The present invention relates to the field of rotary positive displacement pumps.

  Various types of rotary pumps are known, such as gear pumps, lobe pumps, screw pumps and the like.

  The gear pump generally includes two gears, one gear called a drive gear is connected to a drive shaft, and the other gear called a driven gear is rotationally driven.

Applicant's EP1132618 discloses a helical rotary positive displacement gear pump in which the gear has a plurality of teeth that engage without causing fluid confinement, and the overlapping engagement is substantially complete or nearly coincident. Has been. The contents of this publication are incorporated herein by reference. Thus, by combining the tooth profile for preventing the confinement and the helical arrangement of the teeth, pulsation and noise during the pump operation can be reduced.
European Patent Application No. 1132618

  From experiments conducted by the applicant on various gears used in the known types of pumps as described above, the pump noise can be reduced and at the same time, it can be manufactured relatively easily. It has been found that there is a specific range of tooth forms that have the effect of being able to be suppressed. Furthermore, this series of identified tooth profiles has the advantage of high reliability in use, and is particularly advantageous when used in high pressure positive displacement pumps.

  In order to achieve the above object, according to the present invention, there is provided a gear having a plurality of teeth that can be meshed with the teeth of another corresponding gear, and the tooth profile of each tooth is defined in the claims. A gear having a shape is provided.

  In particular, the tooth profile of at least one tooth of one of the two gears is defined by a natural spline function passing through a plurality of nodes having predefined coordinates, and the tolerance is defined by a preferred plurality of nodes. It is ± 1/20 of the theoretical tooth profile. A node is defined by a pair of values {X ′, Y ′} expressed in a Cartesian coordinate system with the center of the pitch circle of the gear as the origin.

  Further according to the present invention, there is provided a rotary positive displacement pump comprising a pair of meshing gears having a tooth profile of the type described above.

  Further features and advantages of the present invention will be understood from the following description of preferred embodiments with reference to the accompanying drawings, which are non-limiting examples.

Referring to FIG. 1, the gear 10 of the present invention is designed to mesh with another corresponding gear (not shown) for use in a rotary positive displacement pump, preferably a high pressure operated rotary positive displacement pump. The tooth H has a plurality of teeth 11 having tooth shapes that can be meshed with other corresponding gear teeth without causing fluid confinement. The tooth profile of the tooth 11 cannot be expressed as a continuation of a simple geometric curve, but a plurality of nodes defined by a pair of values expressed in a Cartesian coordinate system with the center O of the pitch circle 13 of the gear 10 as the origin. 12 by a natural spline function.

  The Applicant has experimentally identified a series of tooth profiles that are particularly suitable for producing gears with 5, 6, 7, 8, 9, 10 teeth. The actual tooth profile of the tooth 11 falls within a tolerance range T which is a range of ± 1/20 of the tooth depth H of the gear.

  As shown in FIG. 2, a gear having 5 teeth has a plurality of nodes defined by a pair of values {X ', Y'} expressed in a Cartesian coordinate system with the center O of the pitch circle P of the gear as the origin. Has a theoretical tooth profile defined by a natural spline function through. The coordinates of the nodes change in the same way as the pair values {X, Y} shown in the list of Table 1.

As shown in FIG. 3, a gear with 6 teeth has a plurality of nodes defined by a pair of values {X ', Y'} expressed in a Cartesian coordinate system with the center O of the pitch circle of the gear as the origin. It has a theoretical tooth profile defined by a natural spline function that passes through it. The coordinates of the nodes change in the same way as the pair values {X, Y} shown in the list of Table 2.

  As shown in FIG. 4, a gear having 7 teeth has a plurality of nodes defined by a pair of values {X ′, Y ′} expressed in a Cartesian coordinate system with the center O of the pitch circle of the gear as the origin. It has a theoretical tooth profile defined by a natural spline function that passes through it. The coordinates of the nodes change in the same way as the pair values {X, Y} shown in the list of Table 3.

  As shown in FIG. 5, a gear having 8 teeth has a plurality of nodes defined by a pair of values {X ′, Y ′} expressed in a Cartesian coordinate system with the center O of the pitch circle of the gear as the origin. It has a theoretical tooth profile defined by a natural spline function that passes through it. The coordinates of the nodes change in the same way as the pair values {X, Y} shown in the list of Table 4.

  As shown in FIG. 6, a gear with 9 teeth has a plurality of nodes defined by a pair of values {X ′, Y ′} expressed in a Cartesian coordinate system with the center O of the pitch circle of the gear as the origin. It has a theoretical tooth profile defined by a natural spline function that passes through it. The coordinates of the nodes change in the same way as the pair values {X, Y} shown in the list of Table 5.

  As shown in FIG. 7, a gear having 10 teeth has a plurality of nodes defined by a pair of values {X ′, Y ′} expressed in a Cartesian coordinate system with the center O of the pitch circle of the gear as the origin. It has a theoretical tooth profile defined by a natural spline function that passes through it. The coordinates of the nodes change in the same way as the pair values {X, Y} shown in the list of Table 6.

If the center distance of the meshing gears of the positive displacement pump or the center distance of the characteristic circle of the gear, such as the pitch circle or outer diameter, is known or specified, the coordinate value {X ', Y'} Can be obtained by simple conversion from the above-mentioned pair of values {X, Y}. When a value representing a point on the tooth profile of the gear is obtained in this way, this value can be used in combination with a known gear cutting device, and in particular, the tool path of the numerical control device can be controlled.

  The manufacturing tolerance of the gear must ensure that the tooth profile of the cut tooth is within the tolerance range of ± 1/20 of the gear toothpaste.

FIG. 1 is a diagram showing a tooth profile of a gear according to the present invention, and shows a tolerance range of the tooth profile with respect to the tooth depth. FIG. 2 is a diagram showing a theoretical tooth profile of a gear having 5 teeth. FIG. 3 is a diagram showing a theoretical tooth profile of a gear having 6 teeth. FIG. 4 is a diagram showing a theoretical tooth profile of a gear having 7 teeth. FIG. 5 is a diagram showing a theoretical tooth profile of a gear having 8 teeth. FIG. 6 is a diagram showing a theoretical tooth profile of a gear having 9 teeth. FIG. 7 is a diagram showing a theoretical tooth profile of a gear having 10 teeth.

Explanation of symbols

10 Gear 11 Tooth 12 Node 13 Pitch circle H Tooth T T Tolerance range O Pitch circle center

Claims (2)

A gear having a plurality of teeth that can mesh with teeth of another corresponding gear,
For gears with 5, 6, 7, 8, 9, or 10 teeth, each has a plurality of predefined coordinates {X, Y} selected from the group consisting of the coordinates listed in Table 1 to Table 6 below. Rotation of high-pressure operation type , characterized in that the tooth profile of each tooth falls within a tolerance range of ± 1/20 of the tooth depth for a theoretical tooth profile similar to the tooth profile defined by the natural spline function passing through the nodes Positive displacement pump gear.

A rotary positive displacement pump comprising two gears according to claim 1, wherein the two gears mesh with each other without causing fluid confinement.

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