GB2223593A

GB2223593A - Gas meter with magnetic coupling

Info

Publication number: GB2223593A
Application number: GB8920754A
Authority: GB
Inventors: Kinya Horibe; Masazumi Kawai; Yasukazu Hoshino; Yoshinori Fukazawa; Masashi Toyama
Original assignee: Yazaki Corp
Current assignee: Yazaki Corp
Priority date: 1988-09-14
Filing date: 1989-09-13
Publication date: 1990-04-11
Anticipated expiration: 2009-09-13
Also published as: DE3930798C2; DE3930798A1; JPH0277621A; GB8920754D0; GB2223593B

Description

223593 A

TITLE OF THE INVENTION

GAS METER BACKGROUND OF THE INVENTION

Field of the invention

The present invention relates to a gas meter for cumulatively displaying the amount of gas consumed.

Description of the Prior Art

Conventionally, as shown in Fig.1, there is known a gas meter of a cumulative display type that indicates the amount of gas consumed by converting a reciprocal movement caused by a measuring film (not shown) in a measuring portion 100 into a rotary movement at a crank portion 110, which then operates a counter portion (an electronic counter) 120 by the rotary movement. The conventional gas meter is for example shown in Japanese Laidopen Patent -Publication No. 62-153713.

In the conventional gas meter, the crank portion 110 and a cap-like rotary member 140 to which the rotary movement generated at the crank portion 110 is transmitted are provided in an upper case 130. In an outer peripheral groove 141 of the rotary member 140, there are mounted a plurality of magnets 150 such that each N pole and each S pole of the magnets 150 are arranged alternately. Moreover, a magnetic reluctance element 160 is arranged at a position of the counter portion 120 which faces the plurality of magnets 150 successively in accordance with the rotation of the rotary member 140.

When the reciprocal movement caused by the measuring film in the measuring portion 100 is converted into the rotary movement at the crank portion 110, which causes the rotary member 140 to be rotated, the magnetic reluctance element 160 successively faces the plurality of magnets - 1 150, thus resulting in reluctance changes due to the magnetic effects from the magnets 150. Thereafter, pulse signals are transmitted from the magnetic reluctance element 160 to the counter portion 120, and a gas flow amount is then cumulatively displayed on a liquid crystal display device 170 which is provided in the counter portion 120.

In the gas meter described above, when the rotar. y member 140 undergoes a single revolution, the same number of pulse signals as the number of the magnets 150 mounted in the rotary member 140 are transmitted to the counter portion 120. That is, when one rotation of the rotary member 140 corresponds to_0.7 I for the gas flow amount, the gas flow amount can be measured or detected by a unit of 0.7/ (the number at the magnets)-,e. In this case, please note that in this type of gas meter, measuring accuracy is improved in accordance with the increase of the number of the poles.

However, as stated above, since a plurality of the magnets 150 are mounted in the outer peripheral groove 141 of the rotary member 140 such that each N pole and each S pole of the magnets 150 are arranged alternately, the number of the magnets 150 or the magnetic poles must be limited. Thus, according to the conventional gas meter, the gas flow amount can not be measured at high accuracy.

Moreover, since both magnetic poles (N poles, S poles) of the magnets 150 must be arranged at the outer peripheral groove 141 of the rotary member 140 reversely and alternately, the number of processes in assembly will need to be increased, thus making production quite troublesome.

Furthermore, it is difficult to reduce the production costs because of such trouble in the manufacturing process.

SUMMARY OF THE INVENTION - 2 k The present invention has been made in order to solve the above-mentioned problems of the prior art, and so its object is to provide a gas meter which can measure a gas flow amount with high accuracy, which can be produced without much trouble, and which can be realized at reduced production costs.

In order to achieve the above object, a gas meter for cumulatively displaying the amount of a gas flow according to the present invention comprises a measuring portion, a measuring film provided in the measuring portion, the measuring film being moved reciprocally by the gas flow, a crank portion for converting the reciprocal movements of the measuring film into rotary movement, a rotary member rotated by the rotary movement transmitted from-the crank portion, the rotary member comprises an integrallymolded resin-bonded magnet in which a plurality of N poles and S poles are arranged alternately, a magnetic sensor arranged at a position which faces the N poles and the S poles of -the plastic magnet successively in accordance with the rotation of the rotary member, whereby producing signals, and a counter portion operated by the signals transmitted from the magnetic sensor to display the amount of the gas flow.

According to the gas meter of the present invention described above, a reciprocal movement caused by the measuring film in the measuring portion is converted into the rotary movement at the crank portion. The rotary movement is transmitted to the rotary member. Then, the rotary member is rotated such that the N poles and the S poles of the rotary member face the magnetic sensor successively and alternately, whereby the signals produced in the magnetic sensor are transmitted to the counter portion. Once the signals have reached the counter portion, the gas flow amount will be cumulatively displayed.

-1 In this case, since the rotary member comprises the integrally-molded resin-bonded magnet in which a plurality of N poles and S poles are arranged alternately, it becomes easy to increase the number of poles in the rotary member.

In addition, since the resin-bonded magnet with the plurality of N and S poles can be produced by a mold, it becomes easy to manufacture the rotary member in comparison with the conventional one in which a plurality of maghets are mounted on the outer periphery of the rotary member.

Further, in the gas meter according to the present invention, the resin-bonded magnet may be formed of magnetic powder as a filler and a binder for binding the powder. As the magnetic powder, a ferrite type magnetic powder such as Ba ferrite and Sr ferrite and so forth can be used. Further, rare earth type magnetic powder such as Sm lCO5" SM2 Co 171 Nd-Fe-B and R-Co (R = Y, Ce, Pr, Pt, La) or/and alnico alloy type magnetic powder can also be used. on the other hand, as the binder, a thermoplastic resin, -such as polyamide, polyacetal, polyethylene, polypropylene, polyphenylenesulfide and fluororesin, a thermosetting resin, such as epoxy resin, phenol resin or urea resin, or a rubber, such as natural rubber, silicon rubber or acrylonitrile-butadiene rubber can be used. As an option, a coating of an epoxy resin or an electrostatic coating may be applied on the surface of the plastic magnet.

Furthermore, the gas meter according the present invention may have a binder for forming the resin-bonded magnet formed of a material having an excellent corrosion resistance to the gas to be measured.

In this case, there are advantage that the rotary member is not corroded by the gas to be measured.

These and other objects, features and advantages of the present invention will be more apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings.

- 4 BRIEF DESCRIPTION OF THE DRAWINGS is Fig. 1 is a partially cutaway side view showing a prior art gas meter.

Figs. 2 to 4(d) show an embodiment of a gas meter which relates to the present invention, in which:

Fig. 2 is an expanded and partially cutaway front view of a gas meter according to the present invention; Fig. 3 is a partially cutaway side view of the same gas meter as that shown in Fig. 2; and Figs. 4(a) to 4(d) are explanatory drawings showing the arrangement relationships between a rotary member and a magnet sensor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the present invention W:1M be described with reference to the drawings.

Fig. 2 is an expanded and partially cutaway front view of a gas meter of the embodiment of the present invention, and Fig. 3 is a partially cutaway side view of the same gas meter as that shown in Fig. 2. In these drawings, there are shown a bottom case 10 which constitutes a gas measuring chamber and an upper case 20 provided with a gas inlet 21 and a gas outlet 22, both of which communicate with the gas measuring chamber.

In the bottom case 10, a pair of film plates (measuring films) 11 are disposed. The film plates 11 repeat their reciprocal operations by a gas which flows into the measuring chamber from the gas inlet 21 and flows out of the gas outlet 22 through the gas measuring chamber. On the front side of the upper case 20, there is provided a counter portion 30. In the upper case 20, there is provided a crank 25 which is equipped with links 23, 24 to be coupled to a wing shaft (not shown) which is driven by the reciprocal rotary movement of the film plates 11.

The crank 25 functions to convert the reciprocal rotary movement of the wing shaft into one-direction rotary movement. To the crank 25 is connected a rotary member 40 which comprises an integrally-molded resin-bonded magnet in which a plurality of N poles and S poles of magnets are arranged alternately. Further, in the counter portion 30, a magnet sensor 50 is disposed at a position where the magnet sensor 50 can face the magnetic poles (N poles, S poles) of the rotary member 40 successively.

The resin-bonded magnet which constitutes the rotary member 40 is formed of magnetic powder hardened with a binder such as, a thermoplastic resin, a thermosetting resin or a rubber. Optionally, an epoxy coating or an electrostatic coating can be applied on the outer surface of the thus formed plastic magnet. The number of the -magnetic poles of the resin-bonded magnet can be set into, for example, 8 poles or 16 poles. (See Figs. 4(a) to 4(d).) Examples of the magnetic powder preferred include a ferrite type magnetic powder, such as Ba ferrite (barium ferrite) or Sr ferrite (strontium ferrite); a rare earth type magnetic powder such as Sm lCO5r SM2 Co 17, Nd-Fe-B or R-Co type (R = Y, Ce, Pr, Pt, La); an alnico alloy type magnetic powder; and magnetic powder such as MnBi, MnAl, Vicalloy.

Examples of the thermoplastic resin include polyamide, polyacetal, polyethylene, polypropylene, fluororesin (polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidenefluoride) and polypheneylenesulfide.

Examples of the thermosetting resin include epoxy resin, phenol resin, urea resin, melamine resin and diallylphthalate.

6 - j Examples of the rubber include natural rubber, silicon rubber, acrylonitrile-butadiene rubber, styrenebutadiene rubber, polyisoprene rubber and cispolybutadiene rubber.

With respect to the corrosion resistance against the gas to be measured, for example, among the thermoplastic resins, polyacetal is the most preferable, followed by polyamideimide, polyamide, fluororubber, vinylidene chloride, ionomer, polypropylene and polyethylene in -that order. Further, among the thermoplastic resins, epoxy resin is the most preferable, followed by phenol resin, urea resin, melamine resin, diallylphthalate in that order. Finally, among the rubbers, syrene-butadiene rubber is the most preferable, followed by polyisoprene rubber and cispolybutadiene rubber in that order.

Incidentally, in this case, an appropriate amount of an additive, such as a plasticizer, a lubricant or a coupling agent may be added to the resing-bonded magnet.

Further, as the magnetic sensor 50, a reed switch, a -Hall element, a Hall IC or a magnetic reluctance element can be used.

In a case where a reed switch is used as the magnetic sensor 50, when the magnetic pole comes near thereto, reeds of the reed switch (tongue portions) formed from a magnetic body are magnetized, and then the distal portions of the reeds are pulled and contact with each other, thereby turning the switch to an ON state. On the other hand, when the magnetic pole goes away from the reed switch, the force pulling the reeds to each other becomes weakened, and then the reeds separate from each other by a spring return force of the reeds in themselves, thus the switch becomes an OFF state.

When the reed switch is used as the magnetic sensor 50, it is arranged to the rotary member 40, for example, as shown in Figs, 4(a), 4(b). In Fig. 4(a), the reed switch 50 is arranged in the radial direction of the rotary member 40, while in Fig. 4(b), it is arranged in the axial direction thereof.

When one read of the switch faces the N pole and the other read faces the S pole, both the reeds are pulled to 5 each other, and then the switch becomes the ON state. Then, in accordance with the rotation of the rotary member 40 from the above position, the pulling force (magnetic force) is gradually weakened until one reed faces thE S pole and the other reed faces the N pole. In this condition, the spring return force of the reeds acts on them, so that the switch becomes the OFF state. Thereafter, the switch becomes the ON state again when the one reed faces the S poleand the other reed faces the N pole. Accordingly, during one revolution of the rotary member 40, the same number of pulses as that of the magnetic poles are outputted from the reed switch, and they are transmitted into the counter portion 30. In this condition, since the reed switch can not be formed in so -small size, the number of the poles of the resin-bonded magnet is limited to eight poles.

Further, in the provision of the Hall element or the Hall IC, when a magnetic field acts in the vertical direction with respect to a current which flows therethrough, a hall voltage is generated in the vertical direction with respect to the directions of the current and the magnetic field.

When the Hall element or the Hall IC is used as the magnetic sensor 50, it is arranged to the rotary member 40, for example, as shown in Figs. 4(c), 4(d). In Fig. 4(c), the Hall element or the Hall IC is arranged in the radial direction of the rotary member 40, while in Fig. 4(d), it is arranged in the axial direction thereof. In this case, when the Hall element or the Hall IC which faces the N pole becomes to face the next S pole in accordance with the rotary movement of the rotary member 40, the direction-of - 8 I the magnetic field which acts against the Hall element or the Hall IC is changed, so that the hall voltage VH is also changed, for example, from + V H to -V H

Accordingly, during one revolution of the rotary member 40, the pulse signals whose number is half of the number of the magnetic poles are outputted from the Hall element or the Hall IC, and then they are transmitted into the counter portion 30. In this case, since the Hall' element or the Hall IC is smaller than the reed switch, it is possible to set the number of the poles of the resin-bonded magnet at sixteen.

Furthermore, in the magnetic reluctance element, reluctance thereof becomes maximum when the direction of the current which flows through the element and the direction of the magnetic field (line of magnetic force) become parallel to each other, while it becomes minimum when the directions become vertical to each other.

In a case where the magnetic reluctance element is -used as the magnetic sensor 50, the element is arranged with reference to the rotary member 40 in the same manner as the Hall element or the like. (See Figs. 4(c) and 4(d).) Accordingly, during one revolution of the rotary member, the pulse signals whose number is the same as the number of the magnetic poles are outputted. When bias magnet that creates bias magnetic field and that displaces strength of the magnetic field including the magnetic reluctance element is used, pulse signals whose number is half of the number of the magnetic poles are outputted, and they are transmitted into the counter portion 30. As is similar to the Hall element or Hall IC, the magnetic reluctance element is smaller than the reed switch, so that it is possible to set the number of the poles of the resin-bonded magnet at sixteen.

The counter portion 30 comprises an electronic counter which is operated by the pulse signals from the magnetic sensor 50 so as to enable the cumulatively display of the amount of gas flow. In the counter 30, there is provided a liquid crystal display device 60 for substantially enabling the cumulative display of the amount of gas flow.

According to the above-mentioned.embodiment, when the film plates 11 repeat their reciprocal operations by the gas flow from the gas inlet 21 to the outlet 22 through the measuring chamber, the wing shaft effects its reciprocal rotary movement. Then, the reciprocal movement of the wing shaft is converted into the one-direction rotary movement at the crank portion 25, thereby rotating the rotary member 40. With the rotation of the rotary member 40, the pulse signals are outputted from the magnetic sensor 50 to the counter portion 30, and then the counter portion 30 is operated and the gas flow amount is cumulatively displayed on the liquid crystal display device 60.

In this embodiment, since the resin-bonded magnet which constitutes the rotary member 40 is integrally molded -by injection molding or compression molding, manufacturing process does not become difficult even though the number of the magnetic poles is increased. Accordingly, it is possible to increase the number of magnetic poles and realize the measurement at high accuracy without any trouble. Further., according to the rotary member 40 of the present invention, the number of steps in the manufacturing process can be much reduced in comparison with the conventional one in which a plurality of magnets are mounted in a ring state. Furthermore, it is possible to fix a shaft 41 to the rotary member 40 by inserting it in a mold for molding the rotary member 40 in advance. Moreover, since the rotary member 40 comprising the resin-bonded magnet is not so fragile as a magnet comprising sintering the magnetic powder, the treatment thereof becomes easy.

- 1 Further, by applying elecrostatic coating or epoxy resin coating on the surface of the rotary member 40, the corrosion resistance thereof to a gas to be measured can be improved.

Furthermore, if polyacetal as the thermoplastic resin, epoxy resin as the thermoplastic resin or styrene-butadiene rubber as the rubbers is used as the binder for the resin-bonded magnet, the magnet is not corroded evenif it is used for a long time, thereby further improving the corrosion resistance.

In summary, according to the gas meter of the present invention, since the rotary member comprises the integrally-molded resin-bonded magnet in which a plurality of N poles and S poles of the magnets are alternately arranged, and the magnet sensor provided at the position where the sensor can face the N poles and S poles successively by rotation of the rotary member, the gas flow amount can be measured at high accuracy, and the gas meter -can be easily manufactured with a low cost.

Additionally, according to the gas meter of the present invention, if epoxy resin coating or electrostatic coating is applied on the rotary member, it is possible for the rotary member to have an advantage, in addition to the above-mentioned advantage, that the rotation member is not corroded by a gas to be measured even if it is used for a long time.

Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.

11 -

Claims

WHAT IS CLAIMED IS:

1. A gas meter for cumulatively displaying the amount of a gas flow, comprising:

measuring portion; measuring film provided in the measuring portion, the measuring film being moved reciprocally by the gas flow; a crank portion for converting the reciprocal movements of the measuring film into rotary movement; a rotary member rotated by the rotary movement transmitted from the crank portion, the rotary member comprises an integrally-molded resin-bonded magnet in which a plurality of N poles and S poles are arranged alternately; a magnetic sensor arranged at a position which faces the N poles and the S poles of the resin-bonded magnet successively in accordance with the rotation of the rotary member. whereby producing pulse signals; and a counter portion operated by the signals transmitted from the magnetic sensor to display the amount of the gas flow.

2. A gas meter according to claim 1, wherein the resin-bonded magnet of the rotary member comprises magnetic powder as a filler and a binder for binding the magnetic powder.

3. A gas meter according to claim 2, wherein the magnetic powder is a ferrite type magnetic powder such as Ba ferrite and a Sr ferrite.

4. A gas meter according to claim 2, wherein the magnetic powder is a rare earth type magnetic powder such as Sm 1C050' Sm 2 co 171 Nd-Fe-B and R-Co (R = Y, Ce, Pr, Pt, La).

12 5. A gas meter according to claim 2, wherein the magnetic powder is an alnico alloy type magnetic powder, or magnetic powder such as MnBi, MnAl or Vicalloy.

6. A gas meter according to claim 2, wherein the binder is a thermoplastic resin, such as polyamide, polyacetal, polyethylene, polypropylene, polyphenylenesulfide or fluororesine.

7. A gas meter according to claim 2, wherein the binder is a thermosetting resin, such as epoxy resin, phenol resin or urea resin.

8. A gas meter according to claim 2, wherein the binder is a rubber such as natural rubber, silicon rubber or acrylonitrile- butadiene rubber.

9. A gas meter according to claim 2, wherein the resin-bonded magnet further comprises an amoint of an additive such as a plasticizer, a lubricant or a coupling agent.

10. A gas meter according to claim 1, wherein an epoxy resin coating or an electrostatic coating is applied onto the resin-bonded magnet of the rotary member.

11. A gas meter according to claim 1, wherein the magnetic sensor comprises a reed switch, a Hall element, a Hall ic or a magnetic reluctance element.

1 12. A gas meter comprising a rotary member, which rotary member comprises an integrally-moulded resin-bonded magnet in which a plurality of N poles and S poles are arranged alternately, a magnetic sensor for detecting and counting the movement of the poles of the magnet relative to the sensor and means for rotating the rotary member relative to the magnetic sensor in accordance with gas flow.

13. A gas meter substantially as hereinbefore described, with reference to, and as shown inj Figures 2, 3 and 4(a) or 10 4(b) or 4(c) or 4(d) of the accompanying drawings.

14. Any novel feature or combination of features described herein.

is Published 1990 a, The Patent Office. State House. 66771 High Holborn, London WCIR 4TP. Purther copiesmaybe obtainedfroin The PatentOffIce Sales Branch. St Ma,3! Crky. Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd. St Mary Cray. Kent. Con 187