JPH0135287B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a twin rotor type flowmeter in which a pair of non-circular rotors are rotatably housed in a casing.

[Conventional technology]

Conventional twin rotor type flowmeters receive loads in the thrust direction with a thrust ring-shaped bearing fitted around the outer periphery of a shaft that passes through the rotor in order to maintain clearance between the non-circular rotor and the inner surface of the casing. It is a structure that maintains

[Problem that the invention seeks to solve]

In the conventional structure, since the ring surface is subjected to sliding motion at a portion away from the center of rotation, there is a large frictional resistance, which results in internal leakage of the fluid to be measured inside the instrument chamber, which reduces the metering function. A method in which the shaft end fixed to the rotor fitted into the shaft hole of the casing side plate is supported by a thrust bearing is a method in which solid foreign matter flowing mixed with the fluid to be measured enters the bearing part and accumulates, causing the bearing surface to become stagnant. It bites and causes damage. It is important that the rotor, which performs the measurement function of a positive displacement flowmeter, rotates lightly within the instrument chamber without encountering resistance and with few mechanical contact parts.

[Means for solving problems]

An object of the present invention is to simplify the structure of a positive displacement flowmeter and improve the measurement accuracy as an industrial meter by using a mechanism with a reduced frictional resistance portion of the rotor.

In the present invention, a non-circular rotor having a shaft hole on only one side is rotatably fitted into an upright fixed shaft inside a casing, and the radial load during rotation is received by the fixed shaft and the weight of the rotor is transferred in the thrust direction or onto a flat surface inside the casing. By receiving it at the center of rotation on the inner surface, the frictional resistance due to contact rotation in the axial direction can be made extremely small, which has the advantage of increasing the sensitivity of the instrument. This is because the rotor's own weight is received at the center of rotation, so the contact area that receives the load is small, and the sliding range is also small, so rotational friction, which is the cause of instrumental error, is significantly reduced.

〔Example〕

Figure 1 is a horizontal cross section of a non-circular gear type flowmeter,
The figure shows a cross section taken along the line A-A' in FIG. The shaft holes of the non-circular gear rotors 1 and 2 are fitted into the shafts 3 and 4, and the rotors 1 and 2 rotate freely. The shafts 3 and 4 stand upright in the instrument room with their bases fixed to the upper cover 7 attached to the casing 5 with screws 6. The fluid to be measured flowing through the inlet 8 and outlet 8' of the casing passes through the confined space between the instrument chamber 9 and the rotor 1.
Thrust bearings 10 and 11 are inserted and fixed into the lower ends of the shaft holes of rotors 1 and 2 to perform the measuring function, and the spherical end surfaces 12 and 13 of both bearings are in contact with the bottom surface of the casing 5, and the lower Clearance 14 and upper clearance 15 are maintained. The tip of the bearing is in contact with the bottom surface of the casing at the center of rotation of the rotor and rotates while supporting the mass of the rotor in a so-called top state, so that there is almost no rotational resistance and smooth rotation is performed. The radial load due to the inertia of the rotor is received by the shaft hole, and only the mass of the rotor is applied to the thrust bearing, so there is no risk of the contact parts 12 and 13 being worn out, no solid foreign matter gets mixed in, and the clearances 14 and 15 change. By not doing so, the accuracy of the instrument is maintained. In FIG. 2, symbol 16 indicates a magnet, and 17 indicates a sensor portion of the measuring mechanism, but other applications such as a magnetic coupling mechanism are also possible.

Figure 3 shows a disc-shaped bottom cover 9 on the bottom surface of the casing 5.
are attached to form the main body of the casing, and thrust bearings 16 and 17 are attached to the bottom cover 9 to form the rotors 1 and 2.
2 shows a vertical cross-section of another embodiment provided at the center of rotation. The rotors 1 and 2 each have a bearing hole above the center of rotation, and have a flat lower end surface. Bearings 16, 17
has a spherical upper surface and is embedded in the hole drilled in the bottom cover 9, and its top surface is convex by about 0.02 mm from the bottom surface and supports the rotor to maintain a predetermined clearance.

FIG. 4 is a plan view of the bottom cover 9, showing the positions of the bearings 16 and 17. A notch 18 is provided so that only the effective portion contacts the end face of the rotor. Although the rotor rotates with a small gap maintained between it and the casing side plate and is not in mechanical contact, the shape of the cutout portion is effective in reducing the influence of viscous resistance in the case of high viscosity fluids such as heavy oil. The contact portions 12 and 13 of the thrust bearing are effective for lubrication because they facilitate the formation of an oil film due to their sliding action at positions away from the center of rotation.

Note that the horizontal shaft configuration is also included in the present invention, and for example, the thrust bearing 1 shown in FIG.
It is possible to have a structure in which the inner surfaces of the shaft holes 0 and 11 are brought into contact with the tip surfaces of the fixed shafts 3 and 44 to maintain side clearances 14 and 15. In addition, it is also possible to have one of the rotors have an indicator transmission shaft structure, and the invention is not limited to the elliptical gear rotor of the above embodiment, but also includes an application example of a roots rotor within the technical scope of the present invention, Both are included as long as one of the bearings has such a configuration. In other words, the present invention has a structure that correctly maintains the minute clearance between both end faces of the rotor and the inner wall surface of the casing, minimizes the load in the thrust direction of the rotor, and reduces rotational resistance, and the rotating shaft is adjusted to vertical and horizontal positions. In either case, in order to maintain clearance between both end faces, either the end face of the fixed shaft standing upright in the casing or the end face in the closed shaft hole of the rotor is made into a protruding spherical surface, and these both ends constitute Application examples in which the contact sliding surface maintains a clearance between the other end surface of the rotor and the inner wall surface of the casing are also included within the scope of the claims. The pocketless structure, which has a small accumulation area for the measured flow rate, is particularly excellent as a food flow meter with a simple structure that is convenient for disassembly and assembly.

〔Effect of the invention〕

According to the present invention, the structure of the positive displacement flowmeter is simplified and the measurement accuracy is improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention in which a thrust bearing is fixed to the rotation center axis of a rotor of a non-circular gear type flowmeter, and FIG. 2 is a cross-sectional view taken along line A-A' in FIG.
FIG. 3 is a longitudinal sectional view showing another embodiment, and FIG. 4 is a plan view of the bottom cover of the embodiment shown in FIG. 1, 2...non-circular rotor, 3, 4...fixed shaft,
5...Casing, 7...Casing top cover, 9...
...Casing bottom cover, 10, 11... Thrust bearing member, 12, 13... Thrust bearing contact part, 1
4,15...Side clearance.

Claims (1)

[Claims] 1 In a twin rotor type flow meter constructed by a pair of non-circular rotors engaged with each other and housed in a measuring chamber, one of the shaft holes at the center of rotation is closed. is rotatably housed in a fixed shaft that stands upright in the casing, and the rotor end face is placed at the center of rotation on the flat inner surface on the other side of the casing or on the flat end face on the side where the shaft hole of the non-circular rotor is closed. In order to maintain a minute gap between the inner surface of the casing and the inner surface of the casing, a protrusion with a corresponding minute dimension is provided. A twin rotor type flow meter that is characterized by maintaining a very small distance.