JPS6347914B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an internal gear pump having two gears (an inner rotor and an outer rotor) with a difference in the number of teeth of one. [Prior Art] Conventionally, as this type of gear pump, a trochoid pump that utilizes trochoid tooth profiles as the tooth profile of an inner rotor and an outer rotor has been widely used. In this trochoid pump, each tooth of the inner rotor is brought into contact with each tooth of the outer rotor, and pressurized oil is discharged by increasing or decreasing the space formed between each contact part. The position of the inner rotor moves as the space increases or decreases, that is, as the inner rotor rotates. In this way, in the trochoid pump, a large number of contact parts move as the inner rotor rotates, so in order to ensure smooth movement, it is necessary to minimize tooth profile errors. However, in trochoid pumps, each tooth profile of the inner rotor and outer rotor is formed by a trochoid curve, which is more complex than a straight line or circular arc, so it is extremely difficult to manufacture the inner rotor and outer rotor, and it is difficult to make a comparison. Large tooth profile errors are likely to occur. When a large tooth profile error occurs, the teeth of the inner rotor and the outer rotor repeatedly come into contact with each other and separate from each other, resulting in a problem that relatively large noise is generated. [Object of the Invention] This invention was made to solve the above-mentioned problems, and an object of the invention is to provide an internal gear pump that can suppress noise to a low level. [Structure of the Invention] In an internal gear pump, it is only necessary to divide the space formed between the inner rotor and the outer rotor into a suction side and a discharge side. This is based on the novel idea that there is no need for the teeth of the inner rotor and outer rotor to be in contact with each other. That is, in this invention, the tooth profiles of the tooth tips and tooth bottoms of the inner rotor are formed by circular arcs that are substantially in contact with each other, while the tooth profiles of the tooth tips of the outer rotor constitute the tooth bottom of the inner rotor. Consisting of a circular arc with a radius of curvature approximately equal to the circular arc,
The tooth bottom portion of the outer rotor is formed to have dimensions equal to or larger than the tooth tip portions of the inner rotor. In this way, if arcuate tooth profiles are used as the tooth profiles of the inner rotor and outer rotor, the teeth required to divide the space formed between the inner rotor and outer rotor into the suction side and the discharge side can be They only touch, and the other teeth do not touch each other. Therefore, compared to a trochoid pump, the number of contact points between the inner rotor and the outer rotor can be reduced. Moreover, since the tooth profile is constituted by a circular arc, which is a simple curve, the inner rotor and the outer rotor can be manufactured easily, and the accuracy of the tooth profile can be improved accordingly. As a result of the reduction in the number of contact points and the improvement in tooth profile accuracy, the internal gear pump of the present invention produces less noise. In addition, in the case of a trochoid pump, as a result of each tooth of the inner rotor and outer rotor coming into contact, a plurality of mutually independent spaces are formed on the suction side and the discharge side, but the internal gear pump of the present invention In this case, one large space is formed on the suction side and the discharge side, which corresponds to a plurality of spaces in a trochoid pump that communicate with each other.
As a result, pressure fluctuations within the space can be suppressed to a small level, and pulsation of the discharged pressurized fluid can be reduced. [Example] Hereinafter, an example of the present invention will be described in attached No. 1.
This will be explained with reference to the figures and FIG. In addition, the first
The figure shows the tooth profiles of the inner rotor and the outer rotor, and FIG. 2 shows the meshing state of these two rotors. In these figures, numeral 1 indicates an inner rotor having n (n≧2) teeth, and numeral 2 indicates n+1 teeth.
The outer rotor has two teeth. The inner rotor 1 and outer rotor 2 are each formed into tooth shapes as follows. The tooth profile of the inner rotor 1 is composed of a circular arc with a radius R ₁ that forms a tooth tip 11 and a circular arc with a radius R ₂ that is in contact with this circular arc and forms a tooth bottom 12 . Here, the tip circle radius of the inner rotor 1 is a,
The radius of the root circle is b, and the center of the inner rotor 1 is
A straight line passing through O ₁ and passing through the center C ₁ of an arc with radius R ₁ is
axis, perpendicular to this X-axis, and the center of inner rotor 1
If the straight line passing through O ₁ is the Y axis, the radii of the two circular arcs R ₁ and R ₂ can be found from the following equations. (X _{1 - X 2} ) ² ₊ (Y _{1 -} Y ₂ ) ² = ₍ ^R ₁ + _{R 2 ) 2} However _, Coordinates of center C ₁ of arc with radius R ₁ (X ₁ , Y ₁ ) Coordinates of center C ₂ of arc with radius R 2 (X ₂ , Y ₂ ) θ ₁ =∠C ₁ O, C ₂ = π/ It is n. On the other hand, the tooth root radius c and the tooth tip radius d of the outer rotor 2 are determined from the following equation in relation to the inner rotor 1. o=a+e+Δa d=b+e+Δb where e; Eccentricity=(a-b)/2 O≦Δa≦0.25mm O≦Δb≦0.25mm. In addition, the tooth profile of the outer rotor 2 is
It is composed of a circular arc with a radius R ₃ forming a , a root circle with a radius c, and a circular arc with a radius R ₄ that is tangent to these arcs and the root circle. radius of two arcs
R ₃ and R ₄ are set as follows. R ₃ =R ₂ +ΔR R ₄ ≦R _1However , O≦ΔR≦1.5mm. In addition, when R ₄ = R ₁ , the dimension of the tooth bottom portion 22 of the outer rotor 2 is the same as that of the inner rotor 1.
When R ₄ <R ₁ , the dimension of the tooth bottom portion 22 of the outer rotor 2 is larger than the dimension of the tooth tip portion 11 of the inner rotor 1 . Inner rotor 1 and outer rotor 2 configured in this way, the outer rotor 2 is rotatably provided in a casing (not shown) and the inner rotor 1 is engaged with the outer rotor 2, similar to a conventional trochoid pump. It is designed to rotate in the direction of arrow A in FIG. 2 in a hanging state. and,
In the state shown in Fig. 2, there is a space separated from each other between the inner rotor 1 and the outer rotor 2.
S ₁ and S ₂ are formed, hydraulic oil flows into the space S ₁ from the suction port 3, and pressure oil is discharged from the space S ₂ to the discharge port 4. [Example] Next, the results of noise tests conducted on the pump according to the present invention and a conventional trochoid pump will be introduced. The specifications of the pump according to the present invention are as follows, and the specifications of the conventional trochoid pump are as follows: The discharge amount is the same as that of the pump of the present invention, and the inner rotor and outer rotor have the same tip diameter. It was decided that

[Table] The test results are as follows. Note that noise measurements are performed using a FET analyzer (frequency analyzer).
In addition, the hydraulic oil is #30 mechanical hydraulic oil, and the oil temperature is 100℃.
And so.

〔Effect of the invention〕

As explained above, according to the internal gear pump of the present invention, the tooth profiles of the tooth tips and the tooth bottoms of the inner rotor are formed by circular arcs that are substantially in contact with each other, while the tooth profiles of the tooth tips of the outer rotor By forming the tooth profile into an arc having a radius of curvature approximately equal to the arc constituting the tooth bottom of the inner rotor, and by forming the tooth bottom of the outer rotor to have dimensions equal to or greater than the tooth tips of the inner rotor. Since the space between the inner rotor and the outer rotor is divided into two spaces, one communicating with the suction port and the other communicating with the discharge port, the noise of the pump during operation can be kept low. Moreover, effects such as being able to reduce pulsation of the discharged oil can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view showing tooth profiles of an inner rotor and an outer rotor according to the present invention, and FIG. 2 is a partially omitted view showing an embodiment of the present invention. 1...Inner rotor, 2...Outer rotor, 11...Tooth tip, 12...Tooth bottom, 21...
Tooth tip, 22... Tooth bottom.

Claims (1)

[Claims] 1. In an internal gear pump equipped with an inner rotor having a number of teeth of n (n≧2) and an outer rotor having a number of teeth of n+1, the inner rotor has a tooth tip portion and a tooth bottom portion. Each of the tooth profiles is formed by an arc that substantially touches each other, and the outer rotor is formed by an arc whose tooth profile at the top of the tooth has a radius of curvature that is substantially equal to the arc that forms the bottom of the tooth of the inner rotor. and the tooth bottom portion thereof is formed to have dimensions equal to or larger than the tooth tip portion of the inner rotor, so that the space between the inner rotor and the outer rotor is a space communicating with the suction port, An internal gear pump characterized by being divided into only two spaces: a space communicating with a discharge port.