JPS631472B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal gear type fluid machine, such as a fluid pump or a fluid motor, which has an internal gear with an internal disc meshing with a pinion with an external disc.

Various types of internal gear type fluid machines such as fluid pumps and fluid motors have been proposed, but conventional ones do not always have enough power over the entire range of possible tooth numbers when the number of teeth is changed. In the case of a pump, for example, it is not possible to obtain a large discharge amount compared to the size of the machine, and the meshing between the internal gear and pinion is not good, so Since proper meshing action cannot be obtained, a lot of vibration and noise are generated, and since the surface of each tooth tip is tilted against the direction of rotation of the gear, not only does the force applied to the surface of the tooth tip become large, but also The relative sliding amount between the surface of the tooth tip of the internal gear and the surface of the tooth tip of the pinion increases, thus creating a gap between the internal gear and the pinion, which reduces efficiency, and therefore requires In order to obtain a high output, the machine had to become large in size.

In the internal gear type fluid machine of the present invention, the meshing tooth surfaces of the internal teeth of the internal gear roll on a fixed circle coaxial with the axis of the internal gear, and the rolling circle has the same diameter as the fixed circle of the pinion. The inner cycloid is determined by the equidistant line from the inner cycloid formed by the inner cycloid, and the inner cycloid is determined by a fraction whose denominator is the diameter of the fixed circle and the numerator is the diameter of the fixed circle of the pinion. It is characterized in that it is formed to be equal to an irreducible fraction whose denominator is the number of teeth and whose numerator is an integer greater than or equal to 2 and less than or equal to the number of teeth of the internal gear minus 2.

In the internal gear type fluid machine of the present invention, the tooth profile of the internal gear is defined by the envelope of a rolling circle of the same diameter centered on the internal cycloid of the internal gear.
It is represented as an equidistant line of the endocycloid. The internal cycloid of the internal gear used in the present invention has a pitch circle or fixed circle (hereinafter referred to as fixed circle) of the pinion with respect to the center of the pitch circle or fixed circle of the internal gear (hereinafter referred to as fixed circle). means that a rolling circle of equal diameter is formed by rolling on a fixed circle of an internal gear, which does not reach its starting point until at least two full revolutions;
For example, the ratio of the fixed circle diameter of the pinion to the fixed circle diameter of the internal gear is 3/9, or 1/9 excluding 6/9.
2/9, which further excludes 1/9 and 8/9 among endocycloids having a value of 9 to 8/9;
Cases of 4/9, 5/9, and 7/9 fall within the scope of the gear of the present invention. In the case of 1/9 and 8/9, the teeth are arcuate in the case of an Eaton gear system, and in this Eaton gear system, the engagement in the tip region is not satisfactory because a gap always occurs between the teeth. Furthermore, in the present invention, two rolling circles whose total diameter is equal to the diameter of the fixed circle form the same endocycloid, so two cases, 2/9 or 7/9 and 4/9 or 5/9, are suitable.

Figure 5 shows the drawing of a point on the rolling circle that reaches the starting point after making two revolutions on the fixed circle of the internal gear with respect to the center of the fixed circle when generating an internal gear with 7 teeth. The endocycloid is shown as an example. Since the number of teeth on the internal gear is odd, here the number of revolutions until the point producing the endocycloid reaches its starting point again must be an even number. In the case of 7 teeth, practically only 2 revolutions can be selected here. As shown in Figure 6, in the case of a large number of teeth, such as 21 teeth, in order to prevent the teeth from becoming flattened, the point at which an endocycloid is generated is 4.
Preference is given to endocycloids which after rotation reach the starting point on the fixed circle of the inner gear again.

As is clear from the above, by correctly selecting the ratio of the rolling circle diameter to the fixed circle diameter of the internal gear within the above-mentioned limits, the freedom of the tooth profile becomes increasingly greater as the number of teeth increases. becomes. For example, when the number of teeth is small, such as 7 teeth for an internal gear, there is little freedom. In this case, the ratio of the rolling circle diameter to the fixed circle diameter of the internal gear is 1/
7, 2/7, 3/7, 4/7, 5/7 or 6/
It must be proportional to 7. In the case of the invention, which does not include the Eaton gear system with the drawbacks mentioned above, only the endocycloids determined by the fractions 2/7 or 5/7 and 3/7 or 4/7 remain.

In many cases, it is sufficient for the tooth surfaces of internal gears to be ground from the tooth tip to the fixed circle of the endocycloid. In such a case, the engagement range is limited to the tooth flank portion between the tooth tip and the fixed circle. The rest of the tooth surface is of course freely machined and does not come into contact with the pinion teeth. When the teeth of an internal gear have an end face with a certain degree of expansion in the circumferential direction of the tooth end circle, in other words, when the tooth has an end face, the tooth end face and the tooth face are separated before hardening and polishing. It is advantageous to cut the ridge between them diagonally. In general, in the case of the gear machine according to the invention, the tooth flanks of the pinion are also determined in principle by the rolling movement of the pinion in the internal gear.

In particular, at least the upper half of the tooth profile of the pinion is determined by the rolling motion of the pinion in the internal gear, and at least the upper half of the tooth profile of the internal gear is perpendicular to the internal gear. It can be formed into a circular arc in the cross section. This arc contacts, at least approximately at the tooth end, an equidistant line that determines the tooth flank of the internal gear meshing with the pinion. The radius of the arc enclosing the equidistant line with the smallest possible distance is equal to or only slightly larger than the radius of curvature of the equidistant line at the contact location. The outermost tooth flanks of the two teeth of the hypothetical internal gear are defined by a common arc in at least the upper half of the tooth flanks. Said opposite tooth flank is the outermost tooth flank of a series of tooth groups whose number of teeth is equal to the denominator of said fraction. In this case, the tooth surface of the pinion is ground at least the upper half of the tooth. This type of polishing method has the great advantage that polishing can be done using a polishing tool that pivots about an axis parallel to the axis of the workpiece to be polished.

If the above conditions are not met, a relatively complex device is required for accurate grinding of the pinion tooth surface. Another method for polishing the pinion tooth surface is to grind this tooth surface by indexing. This method is easier for pinions than for internal gears.

Hereinafter, the present invention will be explained in the form of embodiments with reference to FIGS. 1 to 4. In this connection, it should be pointed out that the illustration of the device according to the invention has been simplified below in order to make the principle easier to understand.

The gear machine shown in FIGS. 1 and 2 has a two-part casing 3, in which an internal gear 1 is provided.
is rotatably mounted. A pinion rotation axis 4 extends through both bearing bushes of the casing 3. This machine is equipped with an inflow hole 5 and an outflow hole 6, which are indicated by a broken line pattern in FIG.
And if the pinion is driven, this machine is a gear transmission pump. The moon-shaped pieces commonly used in this type of gear machine have been omitted from the drawing for convenience. When introducing the processed fluid through one of the two holes, the machine acts as a motor with the rotating shaft 4 as the drive shaft.

The gear device of the internal gear that meshes with this pinion will be explained below with reference to FIG. In the internal gear section shown here, the fixed circle F has a radius rF. Internal cycloid H that determines the tooth surface of internal gears
is caused by the rolling of a rolling circle R with radius rR on a fixed circle F. In that case, point P on the rolling circle describes an endocycloid. The same internal cycloid is also produced by rolling on a fixed circle F in the opposite direction of rotation of a rolling circle R' with radius R'=rF-rR. In the example shown here, the internal gear 1 has nine teeth. Correspondingly, in the case of the gear machine of the present invention which is not an Eaton gear as described above, the radius rR of the rolling circle R is equal to 2/9 or 4/9 of the fixed circle radius rF, and the rolling circle
The radius rR' of R' is 7/9 or 5/5 of the fixed circle radius rF.
Equal to 9. In the case of 4/9, the total tooth depth becomes too large, so that the teeth necessary to ensure the desired engagement can no longer have a ridge-shaped tooth tip, but instead have a tooth surface. . This is a disadvantage for pinions, which need to have a very small number of teeth. The ratio of rolling circle radius rR to fixed circle radius rF is therefore chosen to be 7:9 or 2:9. For the production of internal gears, the grinding tool is moved along an endocycloid formed by a point on the rolling circle that reaches its starting point after two revolutions of its axis about a fixed circle center. Thereby, the circumference of the polishing tool with radius rS forms an equidistant line E with respect to the endocycloid. In fact, as shown in the drawing, the equidistant line does not touch both the two tooth flanks 1a and 1b facing each other of two adjacent teeth of the internal gear (the internal gear It contacts only those tooth flanks 1b which have exactly the shape of an equidistant line (as seen from the center point of The polishing tool is free from the tooth surface 1a. As a result, only a small amount of reaction force acts on the polishing tool during polishing. When the outer abrasive tool is worn out, the abrasive tool can be fed towards the tooth flank 1b. As can be seen in the drawings, the internal gear assembly is pre-machined before grinding and hardening in such a way that the grinding tool is free in the area outside the fixed circle. In this unpolished area, no contact between the internal gear and the pinion occurs. The teeth are then ground only within the area 1d at most.

The desired gear arrangement is ground by the method already briefly described in FIG. 3, ie by guiding the shaft of the grinding tool along an endocycloid of the type described above. When the tooth flanks 1b of all the teeth have been polished as shown in FIG. Surface 1a
It is sufficient to adjust the angle such that the angle is machined by the circumference of the abrasive tool. For ease of understanding, it is assumed in this description that the abrasive tool is not worn, does not need to be sent elsewhere, and that the entire tooth flank is machined in one stroke. Of course, the reality is different and the abrasive tool wears out. It is also necessary to feed the abrasive tool radially outwardly relative to the internal gear. The processes that are well known in this polishing technique will not be described in detail here in order to provide a better understanding of the invention.

Next, we will describe the simplest method of manufacturing a pinion that meshes with an internal gear. In this case, the invention is based on the basic idea that if the pinion rotates correctly in the internal gear, each point of the pinion also describes an endocycloid. The fixed circle of the internal gear is a fixed circle with respect to the internal cycloid H, and the fixed circle of the pinion rolls on it. The fixed circle diameter of the pinion is the diameter of the rolling circle forming the pinion cycloid. Then, an internal gear segment as a processing tool having the same tooth profile as the pinion is fixedly arranged, the segment is assumed to be an internal gear, and when the pinion cycloid is drawn within the internal gear, a similar rolling motion is generated. When the pinion is rolled against the segment, the tooth flanks of the pinion are precisely ground by the internal gear segment as a tool.

Although it is possible to produce a very accurate pinion according to the method described above, it is not possible to harden this pinion without also creating some distortion. In order to eliminate this difficulty, the shape of the tooth flank of the internal gear is replaced by an adapted circular arc for grinding of the tooth flank of the pinion.

The geometric basis for this is represented in FIG. A portion of the teeth of the pinion 2 as well as a portion of the tooth profile of the internal gear 1 are shown here. The internal gear has a pitch circle or fixed circle Ta with radius ra. The pinion has a pitch circle or fixed circle Ti with radius ri. The momentary contact point of both circles is designated by B. The center point of the pinion is always on the straight line connecting the center point of the internal gear and the contact point. The rolling motion of the pinion in the internal gear can be easily imagined by mounting the pinion on a table of a processing device or the like that rotates around the center point of the pinion. This table is mounted on an eccentric shaft that rotates around the center point of an assumed fixed internal gear. The rotation speed of the eccentric shaft that rotates around the assumed center point of the internal gear, and the rotation speed of the table that rotates around the center point of the pinion on the eccentric circle of the eccentric shaft and holds the internal gear. The ratio is the ratio between the number of teeth on the pinion and the difference between the number of teeth on the internal gear and the pinion, or the ratio between the fixed circle radius of the pinion and the difference between the fixed circles of the internal gear and each fixed circle of the pinion. Proportional.

As shown in Fig. 4, both outermost tooth flanks of a group (inclusive of two teeth in Fig. 4) (this tooth flank is the endocycloidal equivalent of an internal gear) determined by the distance line) is
It can be replaced by an arc that is close to the equidistant line and touches the tips of both teeth. The arc must be determined so that, over the entire range of the tooth flank, it has a distance from its center point that is equal to or greater than the equidistant line that determines the tooth flank of the actual internal gear. This arc K has a radius rK. The center point must clearly lie on the straight line that cuts the tooth group enclosed by the endocycloid curve in half through the center of the inner gear. Furthermore, the center point of the radius of curvature of the inner cycloid H that actually determines the tooth surface of the inner gear 1 is the evolute line S shown in FIG.
located above. The evolute line is the geometric locus of all curvature centers of the endocycloid. A part of the evolute line S is also shown in FIG. In a preferred embodiment of the invention, the spindle of the abrasive tool guided along the endocycloid H first abrades only the right tooth flank and then the left tooth flank during the working stroke, so that FIG. The outer tip of the middle evolute line S is not suitable as the center point for the radius of curvature of the approximate circle K, but it is a point near the intersection of both evolute lines S with the straight line M. This method allows the center point of the approximate circle to be found.

Another easier and better way to find the center point of this approximation circle is to represent the tooth profile of the internal gear as a strongly enlarged ladder scale, and then represent the inner gear tooth group wrapped by the inner cycloid curve. This method is to draw a bisector that passes through the center of the gear, and then simply use a compass to find the appropriate radius rK.
The distance from the equidistant line of the circular arc must be as small as possible, at least in the area of the teeth in the upper half of the internal gear envisaged.

Thereby, the tooth flank of the internal gear is substituted by a grinding tool SS (Fig. 4) that revolves around the center point Q of the approximate circle K, but the grinding tool SS (Fig. 4) revolves around point Q such that the envelope of is circle K. The connecting line between the polishing tool axis and the circle center point Q is U.

The rod corresponding to the straight line U is rotated by the guide around the center point of the non-eccentric part of the eccentric shaft (i.e. around the center point of the fixed circle of the internal gear), that is, at the same number of revolutions as the eccentric shaft rotates. As shown by rotating Ta, U is always a constant circle Ta
If care is taken to pass through the contact point B of the circle Ti, the abrasive tool will machine the teeth of the pinion 2 as long as the teeth of the pinion are engaged with the substitute mold of the internal gear substituted by the circle K. can do. If the ratio of the number of teeth of the pinion to the number of teeth of the internal gear is not equal to the ratio of the rolling circle diameter of the internal cycloid that determines the internal gear and its fixed circle diameter, the polishing tool SS is Polishing tools only when inside
SS may machine the teeth of the pinion, but when the abrasive tool crosses the tooth groove between the two teeth of the internal gear on its arc, it must not be machined, so the abrasive tool must not be machined while it crosses this. The SS must always be pulled out from the machining area perpendicular to the drawing in Figure 4. As long as the abrasive tool is within the range of the expected internal gear tooth flank, the abrasive tool will machine the corresponding part of the pinion tooth. The unground portion of the pinion tooth profile is made appropriately deep as shown at 40 during pinion pre-machining. When the pinion satisfies the condition that the ratio of the number of teeth of the pinion to the number of teeth of the internal gear is the same as the ratio of the radius of the rolling circle of the internal cycloid forming the internal gear to the radius of its fixed circle, and each of the internal cycloids The two curves are adjacent to each other.
If only one tooth is to be touched, no raising of the abrasive tool is necessary while it traverses the tooth slot of the internal gear. In this case, the tool is disengaged from the pinion blank in order to grind both flanks and the end depth of each pinion tooth in one stroke and return to its arc.

As described above, the present invention has the following excellent effects.

(b) An internal cycloid formed by a rolling circle with the same diameter as the fixed circle of the pinion, in which the meshing tooth surfaces of the internal teeth of the internal gear roll on a fixed circle coaxial with the shaft of the internal gear. The inner cycloid is determined by an equidistant line from And since it is formed so that it is equal to an irreducible fraction whose numerator is an integer less than or equal to the number of teeth of the internal gear minus 2, a point on the pinion's fixed circle is Only after the gear has rotated two or more times inside the fixed circle can it return to its original position, which allows for sufficient tooth depth and module.

(b) Since the tooth depth and modules can be made sufficiently large, the capacity for press-in or discharge of fluid is large, and a small machine can be used to obtain the required output.

(c) Since only enough teeth or modules can be taken, the surface of the tooth tip stands up (not lies down) with respect to the rotation direction of the gear, so the fixed circle of the pinion is the same as the fixed circle of the inner gear. Compared to a cycloid gear, which returns to its original position by rotating once,
Since both tooth surfaces of the internal gear and pinion contact each other at a nearly right angle (contact with a small angle of inclination), force is easily transmitted from one gear to the other. Also, since the tooth surface is not flat, the force applied to the tooth surface is small, so there is no need to make each part large, so a relatively small machine can be used for the output.

(d) Since the surfaces of the gears are not tilted with respect to the rotational direction of the gears, there is little relative deviation between the surfaces of the tooth tips of both gears, and as mentioned above, the force applied to the surfaces of the tooth tips is small. Combined with this, there is less wear on the tooth surface.

(e) There is less wear on the tooth surface, so there is less loss of efficiency.

(F) Since there is less wear on the tooth surfaces, the gap between the internal gear and pinion is small, and there is less operational vibration and noise.

The embodiments of the present invention are as follows.

(1) A patent claim characterized in that the points P delineating one or more endocycloids H that determine the tooth flanks of the internal gear 1 are located on the periphery of a rolling circle (R or R'). Gear machine according to scope 1.

(2) The distance from the internal cycloid H to the equidistant line E is half the linear distance of the polished area of the mutually facing tooth surfaces of adjacent teeth of the internal gear at the closest point of the polished area. The gear machine according to item (1) above, characterized in that the gear machine is slightly smaller than the gear machine.

(3) The tooth surface shape of at least the upper half of the teeth of pinion 2 is determined by the rolling movement of pinion 2 in the assumed internal gear 1c, and that the half part is formed by a circular arc K in a cross section perpendicular to the axis A of the internal gear;
This arc K touches the equidistant line E, which determines the tooth surface of the internal gear 1 that actually meshes with the pinion 2, at least almost at the tooth end, and the radius of the arc K is the radius of curvature of the equidistant line E at the contact point. be the same as or slightly larger, and the tooth surfaces of the assumed inner gear 1c that are closest to both ends of the arched inner cycloidal curve and are outermost are at least in the upper half of the teeth in a common arc K. and the tooth surface of the pinion 2 is ground at least in the upper half of the tooth. Gear machines described in Section.

(4) The number of teeth of the internal gear 1 does not have a common divisor with the number of teeth of the pinion 2, as described in the claims and one of the preceding items (1) to (3). Steel gear machinery.

[Brief explanation of the drawing]

FIG. 1 is a sectional view passing through the rotation axis of the internal gear and pinion of the gear machine according to the present invention, FIG. 2 is a sectional view taken along the - line of FIG. 1, and FIG. 3 is the geometry of the internal gear according to the present invention. Figure 4 is a diagram showing the geometric relationship when the pinion according to the present invention is polished using a movable polishing tool along an arc, and Figures 5 and 6 are internal diagrams. FIG. 3 is a diagram showing an example of an endocycloid forming a helical gear. 1...Internal gear, 2...Pinion, E...Equidistance line, H...Internal cycloid.

Claims (1)

[Scope of Claims] 1. In an internal gear type fluid machine in which a pinion having external teeth internally meshing with internal teeth is arranged eccentrically in an internal gear to convey fluid, Determined by the equidistant line from the inner cycloid formed by the rolling circle with the same diameter as the fixed circle of the pinion, where the meshing tooth surface of the tooth rolls on a fixed circle coaxial with the axis of the inner gear. The inner cycloid has a fraction with the diameter of the fixed circle as the denominator and the diameter of the fixed circle of the pinion as the numerator, the number of teeth of the inner gear as the denominator, and is 2 or more, and the number of teeth of the inner gear An internal gear type fluid machine characterized in that the internal gear type fluid machine is formed to be equal to an irreducible fraction whose numerator is an integer less than or equal to 2 minus 2. 2. The internal cycloid of one tooth surface and the other tooth surface of each tooth of the internal gear is slightly rotated about the center of the internal gear. Gear type fluid machine.