JPS586131B2 - Positive displacement flowmeter rotor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotor for a positive displacement flowmeter having a pair of helical gear rotors that mesh and rotate with each other and are provided with cycloids and trochoids as tooth profile curves.

Regarding the rotor of this type of positive displacement flowmeter, the present inventor has already disclosed a new technology in the specification of Japanese Patent Application No. 52-4019. The basic configuration is a positive displacement flowmeter with a geared rotor, and a locking part that can be locked with a tooth profile that meshes and contacts near the pitch circle and uses a rotor with a pilot gear function. The present invention provides a rotor for a novel positive displacement flowmeter.

Of course, the invention of Japanese Patent Application No. 52-4019 and Japanese Patent Publication No. 57-12444 also discloses a rotor function in which a contact surface is provided at the tooth tips of the rotor body, but the present invention has a pitch circle that is smaller than that of the rotor. It is an object of the present invention to provide a rotor for a positive displacement flowmeter, which is characterized in that it can be locked at a point close to , and has extremely smooth meshing rotation with less friction and sliding.

An embodiment of the present invention will be described below with reference to the drawings.

The tooth profile curve diagram shown in the drawings and FIG. 1 shows an embodiment of the present invention in which the number of teeth of a pair of meshing helical gears is a rotor 1 with four teeth and a rotor 2 with three teeth. This shows a cross-sectional shape perpendicular to the axis of a type flowmeter A, and shows a fluid pressure difference P from the fluid inlet side 4 provided in the casing 3 toward the outlet side 4'.
A pair of rotors 1 and 2 can freely rotate based on =P1-P2.

5 and 6 are the pitch circle and tip circle of rotor 1, 7 and 8 are the pitch circle and tip circle of rotor 2, O1 and O2 are the respective rotor 1,
2, the center of the pitch circle, M indicates the pitch point.

Therefore, the rotors 1 and 2 have tooth profile curves A1B1 and A2B at the addendum and the dedendum, respectively, with the pitch circles 5 and 6 as boundaries.
2, and B1C1 and B2C2.

The details of the tooth profile curves of both rotors 1 and 2 are described in the above-mentioned patent application 1972.
Since it is described in the specification of No.-4019, it will be omitted.

91, 101 and 92, 102 are engaging tooth-shaped curved portions formed on the addendum and the dedendum around points B1 and B2 that are separated from the pitch circles 5 and 7 of both rotors 1 and 2,
For example, an involute curved section is formed with an involute curve, and although point contact is maintained in the cross section perpendicular to the axis, linear contact is maintained along the axial direction, and both rotors 1,
2 are in contact with each other, and the trajectories QMR'A and RMQ' shown by dotted lines centered on the pitch point M function to mesh with each other.

Therefore, the locus with respect to the stationary coordinate system where the intersection points A1 and A2 of the tooth profile curves of both rotors 1 and 2 formed on the addendum in contact with the tip circles 6 and 8 come into contact is S as shown by the dotted line in FIG.
US' and NKN', and the trajectories relative to the rest of the stationary coordinate system where the points B1 and B2 touch are R'S', SR, and Q'.
The contact points shown by arcs N' and NQ completely seal along the threaded tooth surface.

Additionally, in addition to the above structure, a pair of rotors 1 and 2 are formed in the locus of the seal line, as shown in Japanese Patent Application No. 52-4019.
In the axis-perpendicular cross-sectional shape of the rotors 1 and 2, the parts located at the tips of the cycloid teeth formed on the addendum with the pitch circles of both rotors 1 and 2 as boundaries are engaged as arcuate tooth shapes and brought into contact, thereby achieving an engaged state. A rotor for a positive displacement flowmeter that is reliable and has excellent wear resistance can be obtained.

Since the present invention has the configuration described above, the pair of rotors 1 and 2 can exhibit meshing motion without any interference, and the phase changes of the meshing motion are shown in FIGS. 1 to 8.

As is clear from this movement, the trajectories drawn by points A1 and A2 of both rotors 1 and 2 and points B1 and B2 are six circular arcs SUS', NKN', SR, R'S',
NQ, Q'N' and the four straight parts RM, MR', QM,
It can be understood as MQ'.

As described above, the present invention has the problem that impurities in the fluid to be measured may mesh with each other because the engaging tooth profile curved portion formed by, for example, an involute curve is provided near the pitch point of both rotors. In addition to reducing the risk of wear and tear, even if there is point contact in the cross section perpendicular to the axis, line contact is maintained in the axial direction, so the engaged state is ensured and it is practically possible to omit the so-called pilot gear. It has many characteristics such as

[Brief explanation of drawings]

FIG. 1 is a tooth profile diagram in a cross section perpendicular to the axis showing an embodiment of the rotor of a positive displacement flowmeter according to the present invention, and FIG.
FIG. 2 is a state explanatory diagram showing a phase change of the meshing rotation of the rotor. 1, 2... A pair of rotors, 3... Casing, 5, 7... Pitch circles of rotors 1 and 2,
6, 8...Rotor tip circles of rotors 1 and 2, 91, 92
, 101, 102... Engagement tooth profile curved portion.

Claims (1)

[Claims] 1 A pair of helical gears that mesh with each other are used as a pair of rotors, and a cycloid is formed in the addendum and a trochoid is formed in the dedendum with the boundary near the pitch circle of the rotor as the boundary, and the boundary point near the pitch circle is the center, A rotor for a positive displacement flowmeter having an axis-perpendicular cross-sectional shape of a tooth-shaped curve provided with a tooth-shaped curved portion such as an involute that is engaged with a portion of the cycloid and trochoid.