JPS6229730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positive displacement flowmeter in which the rotation of the rotor is static and non-pulsating, and there is no energy exchange between both rotors, and a pilot gear is not required.

Conventionally, roots-type flowmeters are known as positive displacement flowmeters using spur gears, but such flowmeters require a pilot gear and have the disadvantage of pulsation due to the non-uniform rotation of the rotor. is a widely known place.

It is also well known that by forming the rotor into a helical gear and giving it an optimum helix angle, a positive displacement flowmeter without pulsation and without the need for a pilot gear can be constructed.

The present invention has been made by focusing on the above points,
Not only can this be achieved by eliminating the auxiliary structure of the pilot gear, but also by using a continuous contact gear that does not cause a confinement phenomenon in the tooth profile curve, the torsion rate i can be reduced to 1,
2. Construct a pair of helical gears of the same shape and size given by i ₀ (positive integer) as a rotor, thereby making the rotor pulsation-free and allowing energy exchange between both rotors. In addition to making it possible to rotate with zero tooth surface force, a tooth profile with a slip ratio of 0, for example, an arc tooth profile is provided in a part corresponding to the second tooth profile part of the pair of rotors, and the first tooth profile is used to remove waste liquid such as sludge. An object of the present invention is to provide a positive displacement flowmeter that can be adapted to metering.

The theoretical basis of the present invention will be explained below with reference to the drawings.

That is, one embodiment of the positive displacement flowmeter shown in FIG.
It is an explanatory view of a part of a cross section perpendicular to the axis, and 1 and 2 are rotors consisting of a pair of helical gears of the same shape and size formed with an arbitrary number of teeth that mesh with each other, and the rotors 1 and 2 are designed to fit the desired flowmeter body. It is rotatably provided around the axes 3 and 4 within the casing. 5 and 6 indicate the pitch circle and tip circle of rotor 1, 7 and 8 indicate the pitch circle and tip circle of rotor 2, and 9 and 10 indicate the root circles of both rotors 1 and 2, respectively.

Therefore, the curve A ₁ B ₁ C ₁ of rotor 1 and the curve A ₂ B ₂ C ₂ of rotor 2 are tooth profile curves formed in the addendum, respectively, and the curve A ₁ B ₁ and the curve A ₂ B ₂ are both rotor 1,
The curve B ₁ C ₁ and the curve B ₂ C ₂ are each formed as a cycloid tooth shape. Also curve C ₁ D ₁ and curve
C ₂ D ₂ is a tooth profile curve formed on the dedendum of both rotors 1 and 2, and the pitch circles 5 and 2 of both rotors 1 and 2 are
It is formed with a circular arc tooth profile with its center on 7.

Note that the ends of the arcuate tooth profiles located at the tooth tips and tooth bottoms of both rotors 1 and 2 are adjacent tooth profile curves with circular arcs centered on the axes 3 and 4 of the rotors 1 and 2, respectively. It is continuous.

Therefore, a part of each of the tooth profile curves A ₁ B ₁ C ₁ and A ₂ B ₂ C 2 formed on the addendum of the rotors 1 and ₂ has a first tooth profile and an arcuate tooth profile with a slip ratio of 0. 11,1
2. Also, there is a tooth profile, for example, a first tooth profile, which is in contact with a part of each of the tooth profile curves C ₁ D ₁ and C ₂ D ₂ formed in the dedendum of the rotors 1 and 2, and the slip ratio is 0.
The curved portions other than the circular arc tooth shapes 11, 12, 13, and 14 are slightly set aside by an amount Δ to maintain a non-contact configuration.

In this case, the opposite sides of the tooth profile curves appear symmetrically about the radial axis, so their explanation will be omitted.

Thus, a pair of rotors 1 and 2 having the same shape and size as described above have circular arc tooth profiles 11, 12, 13, 14.
When the two contact and rotate without slipping due to their teeth, the locus of the contact point between the two is four circular arcs PMQ,
It can be expressed as P′MQ′, PRQ, and P′R′Q′.

Now, the contact points between the two rotors, ie, the two rotors 1 and 2
Fig. 2 shows the meshing seal line expanded in the length direction.

In the equation, let β be the helix angle of the helical gears constituting rotors 1 and 2, L be the gear length, Z be the number of teeth, and M be the module, L=iR2π/Z/tanβ=iMπ/tanβ... (1) [However, R: the radius of the pitch circle] If i is the torsion rate, then when i = 1 or its vicinity, the rotational torques T ₁ and T 2 of both rotors 1 and ₂ are becomes.

That is, the rotational torque of both rotors 1 and 2 is constant at each meshing position.

In addition, R _r : Radius of the root circle R ₀ : Radius of the tip circle R _c : Distance from the shaft center to the cycloid curve B ₁ C ₁ : Adjacent arc ends A ₁ on the tip circle Similarly, when the torsion rate i is 2, 3,..., i÷
As in 1, T ₁ + T ₂ = constant, and T ₁ - _{T 2} = 0, so the rotation of rotors 1 and 2 is constant without pulsation, and the energy transfer between the two rotors is constant. Therefore, a so-called ideal shape can be obtained without applying tooth surface force.

Next, we will consider the theoretical discharge amount q.

The theoretical discharge amount q is approximately given by the following equation.

q=2πR ² L {(R ₀ /R) ² −1}……(3) Therefore, it can be seen that the larger R ₀ /R is, the larger the theoretical discharge amount q is, which is advantageous, but the following Calculating the relationship between the number of teeth and the number of teeth, (R ₀ /R) max = 1 + 2 sin π / 4Z (4) Therefore, when Z = 2, R ₀ /R = 1.7654 When Z = 3, R ₀ /R=1.5176 When Z=4, R ₀ /R=1.3902. It goes without saying that R ₀ /R is maximum when Z=2, but since the rotor structure necessarily requires a shaft and a bearing, the root diameter of the rotor cannot be made very small. Therefore, it can be said that R ₀ /R=1.5 is the optimum value.

On the other hand, in the case of helical gears, the phenomenon of the tube coming off from the casing must be taken into account. That is, there is a limit to the twist angle β, and the following equation must be satisfied regarding the twist rate i.

i〓(Z-1)-Z/πcos ^-1 R/R ₀ +Z/2
π...... (5) Figure 3 shows the calculation of equation (5).

As is clear from FIG. 3, when Z=2, in order to make the torsion rate i 1, it is necessary to greatly reduce R ₀ /R, which is not practical.

For this, i=1 for Z=3 and i for Z=4.
=1, i=2 are possible, but Z=3 and Z=4
The theoretical discharge amount when (R ₀ /R)max in equation (4) differs considerably, but all of them satisfy the intended purpose as positive displacement flowmeters using continuous contact teeth. It can be said.

Since the present invention exhibits the above-mentioned configuration and operation, the helical gears may be used as a pair of same large rotors of the same shape, and the torsion rate i may be set to i ₀ (a positive integer, preferably 1).
(or its vicinity), and both rotors have a part of the tooth profile curve formed at the addendum and the dedendum, and the tooth profile that contacts this part is constituted and meshed with, for example, a circular arc tooth profile, so it has a sludge-like tooth profile. It is suitable for measuring waste liquid, and can also improve manufacturing accuracy.It is possible to provide high-precision products that can measure flow rates without pulsation and without energy load, and can also be used with hydraulic motors, pumps, and other fluid This has an effect that can also be applied to equipment.

[Brief explanation of the drawing]

Fig. 1 is a tooth profile diagram in a cross section perpendicular to the axis of the main structure of an embodiment of a positive displacement flowmeter according to the present invention, Fig. 2 is a developed view of the same tooth profile seal line, and Fig. 3
The figure is a chart showing the relationship between the theoretical discharge amount and the torsion rate in addition to the relationship with the number of teeth. 1, 2... A pair of identical rotors, 5, 7... Pitch circles of rotors 1 and 2, 6, 8... Tip circles of rotors 1 and 2, 9, 10... Rotors 1 and 2 root circle, 1
1, 12, 13, 14...addendum of rotors 1, 2, circular tooth profile protruding from the outer periphery of the dedendum, curve A ₁ B ₁ C ₁ , curve A ₂ B ₂ C ₂ ...both rotors 1, 2 Tooth profile curves formed on the addendums of the rotors 1 and 2, curve C ₁ D ₁ , curve C ₂ D ₂ ... tooth profile curves formed on the dedendums of both rotors 1 and 2.

Claims (1)

[Claims] 1 Using a continuous contact tooth profile that does not cause a confinement phenomenon in the tooth profile curve, and assuming that the front module M, the tooth profile height L, and the torsion angle β are, the torsion rate i expressed by Ltan/Mπ is i ₀ (i ₀ is a positive A pair of helical gears of the same shape and the same size given by an integer of 1 or its vicinity) are configured as a rotor, and the circular arc tooth profile meshes with a part of the tooth profile curve formed at the addendum and dedendum of the rotor. A positive displacement flowmeter characterized by being provided with.