GB2128341A

GB2128341A - Indicating gas flow

Info

Publication number: GB2128341A
Application number: GB08324864A
Authority: GB
Inventors: Shinji Takashima; Masato Ito
Original assignee: Ricoh Seiki Co Ltd; Ricoh Co Ltd
Current assignee: Ricoh Seiki Co Ltd; Ricoh Co Ltd
Priority date: 1982-09-20
Filing date: 1983-09-16
Publication date: 1984-04-26
Also published as: JPS5945525U; KR840006406A; GB2128341B; GB8324864D0; KR920001428Y1; JPH0412421Y2; HK43391A

Abstract

Low flow through a turbine type gas meter is indicated by the motion of a disc (44) magnetically coupled to the turbine in addition to the normal indicating means. The disc is provided with a pair of magnets 46a, 46b which interact with two magnets on an arm driven by the turbine. <IMAGE>

Description

SPECIFICATION Minute gas flow detector This invention generally relates to a flpw meter and in particular to a detector for detecting the presence of a minute gas flow through a duct.

More specifically, the present invention relates to a minute gas flow detector capable of detecting the presence of a flow of gas such as the one used for keeping seed fire in gas appliances, e.g., 4-5 litres per hour.

Description of the Prior Art Figs 1-3 schematically illustrate a typical prior art gas meter which generally includes a main body section 10, a counter section 20 for calculating cumulatively and displaying the amount of gas flow passed through the main body section 10 and a cover 30 for enclosing the counter section 20 for protection. As shown in Fig.

3, gas is introduced into the gas meter main body section 10 through an inlet port 11 and then discharged out of the main body section 10 through an outlet port 12 to a gas burner (not shown) or the iike. The gas meter 10 includes a rotary valve which is set in rotation when gas flows through the meter 10, and the rotation of rotary valve is transmitted to a pinion 13, which, in turn, is transmitted to the counter section 20 through a reduction gear train 14, whereby the amount of gas used is cumulatively displayed at the counter section 20. In such a gas meter, a pilot display device for indicating the presence of a flow of gas is typically provided.In the illustrated gas meter, it is so structured that a selected gear A in the gear reduction train 1 4 is made observable from the exterior to examine whether it is in rotation or not. However, such a prior art structure is disadvantageous because it is very difficult to detect accurately as well as rapidly the presence of a minute flow of gas in the order of 4-5 litres per hour for use in keeping seed fire in various gas appliances. For example, typically, if a flow of gas is 5 litres per hour, then a peripheral speed of the gear A is approximately 2.5 mm per minute. Thus, it is virtually impossible to accurately judge whether or not such a minute flow of gas is present.

The disadvantages of the prior art are overcome with the present invention and an improved minute gas flow detector is provided.

Therefore, it is a primary object of the present invention to provide an improved detector for detecting the presence of a minute gas flow quickly as well as accurately.

Another object of the present invention is to provide a minute gas flow detector simple in structure and thus easy to fabricate.

A further object of the present invention is to provide a minute gas flow detector reliable in operation and long in service life.

A still further object of the present invention is to provide a minute gas flow detector having an easily observable indicator which may be made practically as large as possible.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

Brief Description of the Drawings Fig. 1 is an exploded, perspective view showing a typical prior art gas meter; Fig. 2 is an exploded, perspective view showing the gas meter of Fig. 1 with its top cover 30 located above; Fig. 3 is a fragmentary, front view showing the gas meter shown in Figs. 1 and 2; Fig. 4 is a plan view showing a gas meter into which one embodiment of the present minute gas flow detector is incorporated; Fig. 5 is a cross-sectional view taken along the V-V line shown in Fig. 4, Fig. 6 is a cross-sectional view taken along the VI--VI line shown in Fig. 4; Fig. 7 is a plan view illustrating an example of indicator plate which may be used in the present minute gas flow detector; Fig. 8 is a front view of the indicator plate shown in Fig. 7; and Fig. 9 is a cross-sectional view taken along the IX-IX line shown in Fig. 7. Referring now to Figs. 4-6, there is shown a gas meter into which the minute gas flow detector constructed in accordance with one embodiment of the present invention is incorporated. As shown, the gas meter 10 includes an inlet port 11 and an outlet port 12, any gas lead into the gas meter 10 through the inlet port 11 is discharged out of the gas meter 10 through the outlet port 12, which may be connected to any desired gas appliance such as a hot water maker. The gas meter 10 also includes a rotary valve 1 5 which is so structured to rotate as gas flows through the meter 10 with its rotational speed proportional to the amount of gas flowing through the meter 10.

Also provided is a worm 1 6 which is operatively associated to the rotary valve 1 5. A pinion 1 7 is provided as operatively associated to the worm 16. The gas meter 10 also includes a counter section 20, a counter cover 30 which encloses the counter section 20 and a pilot indicator section 40 provided at top of the gas meter 1 0.

With such a structure, when the rotary valve 1 5 is set in rotation due to the presence of a gas flow through the meter 10, its rotation is transmitted to the worm 1 6, and the rotation of the worm 1 6 is then transmitted to the counter section 20 through the pinion 17, whereby the amount of gas used is cumulatively displayed at the counter section 20. In accordance with the present embodiment, an arm 1 9 is fixedly mounted on the worm 16 as extending radially from the worm 16, and a pair of small magnets 1 spa and 1 8b is fixedly mounted at each of its free ends as shown. As will be made clearer later, this structure allows to rotate the indicator disc provided at the indicator section 40 to move on a one-to-one basis.

Figs. 7-9 illustrate the detailed structure of one example of the indicator section 4Q, which may be advantageously applied to the meter shown in Figs. 4-6. As shown, an indicator disc includes a transparent cover 41 of acrylic resin, a base 42 of acrylic resin, a magnet support 43 of polyacetals, an indicator plate 44 of aluminum, a protective cover 45 of stainless steel and a pair of magnets 46a and 46b. In manufacture, the pair of magnets 46a and 46b is first affixed to the magnet support 43 and then the indicator plate 44 is fitted onto the magnet support 43.

Thereafter, such an assembled structure is placed between the base 42 and the cover 41 and a contact between the cover 41 and the base 42 indicated by the lower case letter "a" is fused, followed by the step of filling antifreeze 47 into an inner space and then the step of fitting the protective cover 45 thereby completing the indicator disc.

As described before, the gas meter 10 includes the arm 19 which is fixedly mounted on the worm 1 6 and which carries the pair of magnets 18a and 18b on both ends. Thus, the number of rotation of the worm 1 6 is equal to the number of rotation of the rotary valve 1 5. As best shown in Fig. 5, the indicator disc 40 is rotatably supported on top of the gas meter 10 in axial alignment with the worm 1 6 at such a position that the pair of magnets 46a and 46b receive sufficient magnetic interaction applied by the pair of magnets 18a and 18b mounted on the arm 1 9. As a result, when a minute flow of gas causes to rotate the rotary valve 15, the worm 1 6 is rotated, and, thus, through magnetic coupling between the pair of magnets 18a and 18b and the pair of magnets 46a and 46b, the indicator disc 40 is caused to rotate. Such rotation of the indicator disc 40 may be easily observed from the exterior, and, thus, the rotary valve 1 5 may be confirmed to be in rotation, indicating the presence of a flow of gas whatever small it may be.It is to be noted that, in the structure of the present invention, the rotation of the indicator disc 40 may be so set to correspond to the rotation of the rotary valve 1 5 on a one-toone basis.

In one example, the peripheral speed of the indicator plate 44 may be easily set at 10.2 mm per minute for a gas flow rate of 5 litres per hour, which indicates approximately four times improvements over the before-described prior art.

It should however be noted that further improvements may be made quite easily in the present invention because selection of a size for the indicator plate 44 is almost arbitrary, so that the larger the diameter of the indicator plate 44, the higher the accuracy and easiness in detection of gas flow. In the case of the illustrated embodiment, the cover 41 also functions as a magnifier so that detection of rotation of the indicator plate 44 and thus the presence of gas flow is made even more accurate and easier.

While the above provides a full and complete disclosure of the preferred embodiments of the present invention, various modifications, alternate constructions and equivalents may be employed without departing from the true spirit and scope of the invention. Therefore, the above description and illustration should not be construed as limiting the scope of the invention, which is defined by the appended claims.

Claims

1. A device for detecting the presence of a gas flow through a defined flow passage, comprising: rotary valve means which is caused to rotate when said gas flow is present in said flow passage; a first rotary member operatively associated with said rotary valve means; first magnetic coupling means fixedly mounted on said first rotary member; a second rotary member located generally coaxially with said first rotary member; and second magnetic coupling means fixedly mounted on said second rotary member.

2. A device of Claim 1 wherein either one of said first and second magnetic coupling means includes at least one magnet and the other includes at least one magnetically attractable material whereby said first magnetic coupling means may be magnetically coupled to said second magnetic coupling means thereby causing said first and second rotary members to rotate in unison.

3. A device of Claim 1 wherein both of said first and second magnetic coupling means include at least one magnet so that said first and second magnetic rotary members are caused to rotate in unison.

4. A device of Claim 1 further comprising a magnifier disposed in the vicinity of said second rotary member.

5. A minute gas flow detector substantially as hereinbefore described with reference to Figures 4 to 9 of the accompanying diagrammatic drawings.