JPH05296809A - Volume flowmeter - Google Patents

Abstract

PURPOSE:To obtain stabilized high accuracy of a volume flowmeter and to expand the flow-rate measuring range of the volume flowmeter by a method wherein the cause of a drop in the accuracy of the volume flowmeter is reduced to a minimum. CONSTITUTION:Cylindrical bearing members 7, 8 which are provided with bearing holes 7a, 8a are pressed previously into a through hole 5 in an inner tube 1; slender rotor shafts 10 whose ends, on one side, have been fixed and bonded to rotors 9 are brone by means of the bearing holes 7a, 8a in a cantilever manner. A measuring fluid, at a pressure P1, which has been introduced, via a liquid chamber 6a, from a through hole 6 into their bearing parts is pressed and fed, and the rotor shafts 10 are lubricated forcibly.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a volumetric flowmeter, and more particularly to a volumetric flowmeter capable of measuring from a small flow rate to a large flow rate range by reducing sliding friction torque.

[0002]

2. Description of the Related Art As is well known, in a positive displacement flowmeter, a pair of rotors are rotationally driven by a fluid pressure difference of a measurement fluid in a measuring chamber.
The flow rate is measured in proportion to the number of rotations of the rotor, with the volume of the fluid in the space formed by the measuring chamber and the rotor removed by the rotor as a reference flow rate. As described above, since the rotor of the flowmeter rotates in proportion to the flow rate, the positive displacement flowmeter is provided with the rotor shaft and the bearing that supports the rotor shaft. In medium- and small-sized positive displacement flowmeters, the rotor shaft is often fixed in the measuring chamber by embedding one end of the rotor shaft, and the bearing is fitted in the rotor. However, in a large volumetric flowmeter, a so-called shaft-rotation type in which a rotor shaft is inserted and fixed to a rotor and a bearing is mounted on a housing of a main body is mainly used.

The volumetric flowmeter is a volumetric flowmeter which measures the flow rate from the number of rotations of the rotor with the volume of the fluid in the measuring chamber removed by the rotor as a reference volume as described above. An ideal positive displacement flow meter is one in which fluid is removed from the metering chamber without leakage from the rotor over a range of flow rates from zero to a given flow rate. The rotor rotates due to the rotational moment that acts on the rotor due to the pressure difference between the front and rear of the rotor.However, the differential pressure changes due to various factors and the reference volume also changes. It is impossible to realize an ideal positive displacement flowmeter with zero.

As described above, in the actual volumetric flow meter, the reference volume of the fluid removed by the rotor from the measuring chamber is not constant from the small flow volume to the large flow volume, and various error factors are added. One of them is bearing friction. Naturally, the rotational moment acting on the rotor is large at a large flow rate and small at a small flow rate. Taking only bearing friction torque, if the bearing lubrication is sufficient, the friction torque can be ignored compared to the rotation moment of the rotor in the large flow rate range, but it cannot be ignored in the small flow rate range. The rotor stops when it strikes a balance. As a result, the rotation speed and flow rate of the rotor match in the high flow rate region, but in the low flow rate region, the fluid flows out from the minute gap between the rotor and the measuring chamber before the rotor stops, and The rotation of is gradually reduced.

If the rotor is a non-circular gear,
The meshing friction of the gears occurs, and the reaction force due to the pressure generated when the fluid is confined between the meshed tooth profiles acts between the rotor shaft and the bearing. These are other factors that reduce the accuracy of the positive displacement flowmeter. In order to reduce the bearing friction among the above-mentioned factors that reduce the accuracy, it is necessary to reduce the shaft diameter in order to reduce the surface area of the shaft.
If the shaft diameter is made smaller, in the case of a fixed shaft fixed in the measuring chamber, the shaft tends to tilt, and in the case of rotor sticking, the rotor shaft is easily deformed, so that the center of rotation of the rotor is secured correctly. It was difficult to do. Further, in order to reduce the meshing friction torque of the rotor and the shaft friction torque due to the closing pressure, it is necessary to reduce the thickness of the rotor, but there is no suitable structure for the conventional volumetric flowmeter.

[0006]

[PROBLEMS] The present invention has been made in view of the above circumstances, and a bearing structure that reduces friction torque of a bearing portion and a rotor shape provide high accuracy over a large flow rate to a small flow rate range. The purpose of the present invention is to provide a volumetric flow meter having characteristics.

[0007]

In order to achieve the above object, the present invention provides (1)
A rotor having a rotor shaft fixed at one end and projecting in a cantilevered manner at the other end, a cylindrical bearing member having a bearing hole for axially supporting the rotor shaft, and the rotor rotatably housed therein. An inner cylinder having a through-hole for mounting the measuring chamber having one surface opened and the bearing member by press-fitting or adhesion, and the measuring chamber side fixed to the measuring chamber side of the inner cylinder to close the opening of the measuring chamber, And a top lid having an inflow passage and an outflow passage opening on the upstream side and the downstream side sandwiching the rotor, or (2)
A rotor and a rotor shaft that rotatably supports the rotor;
A cylindrical member for fixing the rotor coaxially; an inner cylinder for rotatably accommodating the rotor and having a through hole for inserting and fixing the measuring chamber and an opening on one surface; The cylinder is fixed to the measuring chamber side and closes the opening of the measuring chamber, and is constituted by an upper side having an upstream side and an outflow passage sandwiching the rotor of the measuring chamber, and further, (3) above (1) Or (2), when the rotor is a pair of non-circular gears that mesh with each other, the major axis of the non-circular gear is D, the minor axis is d, and the thickness is t, the ratio of t to (D + d) / 2 1 to
0.1, and (4) In any one of (1) to (3) above, a flange for fixing the upper lid, and an outer casing having an outer peripheral wall into which the inner cylinder is fitted; It is characterized in that it has a through hole penetrating from the measuring chamber of the inner cylinder to the bottom; and a liquid chamber formed by the outer casing and the bottom surface of the inner cylinder to connect the through hole and the bearing hole. Hereinafter, it demonstrates based on the Example of this invention.

1 (a) and 1 (b) are views for explaining a positive displacement flow meter according to the present invention, and FIG. 1 (a) is shown in FIG.
1B is a cross-sectional view taken along the line BB of FIG. 1B, and FIG.
Is a sectional view taken along the line AA of FIG. 1, in which 1 is an inner cylinder, 2 is an outer housing, 3 is an upper lid, 4 is a measuring chamber, 5 is a bearing through hole, 6 is a through hole, and 7 and 8 are bearings. Member, 9 is a rotor, 10 is a rotor shaft,
11 and 12 are packings, 13 is a bolt, and 14 is a fixed flange.

In FIG. 1, an inner cylinder 1 is a molded part having a measuring chamber 4 and a through hole 5 and made of resin, stainless steel or the like. Cylindrical bearing members 7 and 8 are attached to both ends of the bearing through hole 5 of the inner cylinder 1 by press fitting or bonding. The rotor 9 is, for example, a non-circular gear having a shaft fixing hole 9a penetrating therethrough, and the rotor shaft 10 has one end fixed in the shaft fixing hole 9a and the other end protruding downward. Protruding rotor shaft 10
Is supported in the bearing holes 7a and 8a.

The inner cylinder 1 is fitted in the outer casing 2. Outer casing 2
Is a member having a concave portion formed by an inner peripheral wall 2a having an inner diameter slightly larger than the outer diameter of the outer wall of the inner cylinder 1 and a cylinder inner bottom surface 2b, and having a flange 2c on the outer peripheral surface of the upper end. Flange 2c
The depth of the recess reaching from the inner bottom surface 2b of the cylinder is slightly deeper than the height of the inner cylinder 1, and the inner cylinder 1 is placed on the packing 11 inserted into the inner bottom surface 2b of the recess. A through hole 6 penetrating the inner cylinder 1 from the measuring chamber 4 communicates with a liquid chamber 6a in a space defined by the inner cylinder 1 and the inner cylinder bottom surface 2b with the packing 11 as an outer peripheral wall.

Since the surface of the placed inner cylinder 1 on the side of the measuring chamber 4 is slightly higher than the surface of the flange 2c of the outer casing 2, the upper lid 3 is attached to the mounting flange via the port 13 and the nut 13a. By fixing the inner cylinder 1 to 14 and pressing the inner cylinder 1 with the upper lid 3, the opening surface of the measuring chamber 4 of the inner cylinder 1 is elastically sealed by the packing 11. Further, the rotor 9 of the weighing chamber 4 is provided on the upper lid 3.
An inflow passage 3a and an outflow passage 3b communicate with the chambers sandwiching the space.

Next, the operation of the volumetric flowmeter of the present invention constructed as described above will be described. First, in FIG. 1 (a),
When the measurement fluid having the pressure P ₁ flowing from the inflow passage 3a is introduced into the measuring chamber 4, a rotational force based on the pressure difference is generated in one of the meshing rotors 9, 9 to rotate. Rotor 9
The rotation force alternately acts on the respective rotors 9 as a result of the rotation, and the measurement fluid in the measuring chamber 4 is removed and the outflow passage 3b is removed.
More outflow. At this time, the rotor shaft 10 of the rotor 4 is
The outer diameter is as small as about 1/10 to 15 with respect to the major axis D of the rotor 9, and the shaft friction torque at the rotor shaft 10 is minimized. Further, the bearing-side end surface portion of the rotor shaft 10 is lower than the pressure P ₁ on the inflow passage 3a side. Since the pressure on the side of the inflow passage 3a and the pressure on the liquid chamber 6a are equal to each other and the pressure is P ₁ , a pressure difference occurs between the liquid chamber 6a and the bearing end surface portion of the rotor, and the pressure difference causes the measurement fluid to flow into the flow chamber 6a. Through the slight gap between the bearing holes 7a and 8a of the rotor shaft 10 to become the lubricating liquid for the flow shaft 10. Especially in the large flow rate range, the pressure difference increases, so that the shaft lubricity is good, and in the small flow rate range, the small flow limit extends to the small flow range due to the small friction torque. The action of this lubricating liquid can effectively cool the bearing portion.

When the rotor 9 is a non-circular gear,
If the major axis is D, the minor axis is d, and the thickness (tooth length) is t,
By setting the ratio of (D + d) / 2 and t to be 1 to 0.1, the friction torque due to the meshing friction of the rotor 9 and the narrowing pressure due to the meshing are also reduced, and the rotor shaft 10 is made thin and the bearing friction torque is reduced. In addition to the effect of reducing the above, it is possible to reduce the factor of deterioration in accuracy that occurs on the rotor 9 side.

FIG. 2 is a view for explaining another embodiment of the volumetric flow meter according to the present invention. In the figure, 71 and 81 are cylindrical members, and parts having the same functions as those in FIG. The same reference numeral as 1 is attached.

In the volumetric flowmeter shown in FIG. 2, the rotor shaft 10 of the volumetric flowmeter shown in FIG. 1 is fixed, and the rotor shaft 10 is coaxially fixed in the bearing and the through hole 5. The cylindrical members 71 and 81 are fitted into the shaft holes 71a and 81a and fixed axially. One end of the trochanter shaft 10 projects into the measuring chamber 4 and serves as a rotor shaft portion that pivotally supports the rotor 9.
At this time, the tubular member 71 on the side of the measuring chamber 4 slightly protrudes to the side of the measuring chamber 4 and serves as a thrust bearing of the rotor 9. According to this method, since the rotor is only the rotor 9, it is lightweight,
It is possible to rotate even with a small differential pressure with a small flow rate. FIG. 3 is a diagram showing another embodiment of the volumetric flow meter according to the present invention, in which the rotor 9 of the rotor shaft fixed type volumetric flow rate shown in FIG.
5 is inserted and the rotor is axially supported via the bearing 5.

[0016]

As is apparent from the above description, according to the present invention, (1) the rotor shaft has a small diameter to reduce the friction torque of the rotor shaft, and the bearing of the rotor shaft is used as a bearing member. Since the bearing member is formed by press-fitting the bearing member into the through hole formed in the inner cylinder, the coaxiality can be secured even if the shaft diameter of the rotor shaft is reduced. Furthermore, (2) In (1) above, since the ratio of the average value of the major diameter D and the minor diameter d of the non-circular gear to the tooth length t is set to 1 to 0.4, the rotor is thin and the bearing friction is small. Friction torque factors other than torque are also small, and high accuracy is achieved. Furthermore, (3) above (1) or (2)
Since the measured fluid was forcibly pumped and lubricated to the bearing portion of the rotor shaft, the shaft lubrication characteristics are excellent especially in the high flow rate range.
It is possible to reduce the factors that reduce the accuracy of the bearing.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of a volumetric flow meter according to the present invention.

FIG. 2 is a diagram for explaining another embodiment of the volumetric flow meter according to the present invention.

FIG. 3 is a view for explaining still another embodiment of the volumetric flow meter according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inner cylinder, 2 ... Outer casing, 3 ... Upper lid, 4 ... Measuring chamber, 5 ... Bearing through hole, 6 ... Through hole, 7,8 ... Bearing member, 9 ... Rotor, 1
0 ... Rotor shaft, 11, 12 ... Packing.

Claims (4)

[Claims] 1. A rotor having a rotor shaft fixed at one end and cantilevered at the other end, a cylindrical bearing member having a bearing hole for supporting the rotor shaft, and the rotor. A measuring chamber which is rotatably accommodated and has one side opened, and an inner cylinder having a through hole for mounting the bearing member by press-fitting or adhesive bonding, and the measuring chamber side of the inner cylinder is fixed to close the opening of the measuring chamber. The volumetric flowmeter is characterized in that it is constituted by an upper lid having an inflow passage and an outflow passage which are opened on the upstream side and the downstream side with the rotor of the measuring chamber interposed therebetween. 2. A rotor, a rotor shaft that rotatably supports the rotor, and a tubular member that fixes the rotor coaxially.
An inner cylinder that rotatably accommodates the rotor and has a through-hole for inserting and fixing the measuring chamber with one surface open and the tubular member, and a measuring chamber that is fixed to the measuring chamber side of the inner cylinder. A positive displacement flowmeter, comprising an upstream side with an opening closed and a rotor of the measuring chamber sandwiched therebetween and an upper lid having an outflow passage. 3. When the rotor is a pair of non-circular gears meshing with each other, the ratio of t to (D + d) / 2 is 1 where D is the major axis, d is the minor axis and t is the thickness. ~
The volumetric flowmeter according to claim 1 or 2, wherein the volumetric flowmeter is 0.1. 4. A flange for fixing the upper lid,
An outer casing having an outer peripheral wall into which the inner cylinder is fitted; a through hole penetrating from the measuring chamber of the inner cylinder to the bottom; a liquid formed by the outer casing and the bottom surface of the inner cylinder to communicate the through hole and the bearing hole The volumetric flowmeter according to any one of claims 1 to 3, further comprising a chamber.