초록 ▼

A union is adapted to butt two reused plastic bottles at their mouths to provide a teaching aid for simulating the forming of spring and convection due to a pressure difference between two spaces. The union includes a hollow tubular body having a radially extended middle partition. An internal screw

A union is adapted to butt two reused plastic bottles at their mouths to provide a teaching aid for simulating the forming of spring and convection due to a pressure difference between two spaces. The union includes a hollow tubular body having a radially extended middle partition. An internal screw thread is provided on an inner wall surface of the union at each side of the middle partition to engage with an external screw thread on the mouth of the plastic bottle. The middle partition is provided with two symmetrical through holes, each of which is axially divided into two parts by a radially inward projected annular rib. Each part of the through holes is sized for a suction tube of predetermined dimensions to insert thereinto. By inserting two or three suction tubes into different parts of the two through holes, screwing the plastic bottles, one of which is partially filled with liquid, to two ends of the union, and turning the union upside down to locate the bottle having liquid at an upper position, the forming of springs and convections at different rates could be simulated in the bottles.

대표청구항 ▼

1. A union for butting two reused plastic bottles at their mouths to provide a teaching aid for simulating the forming of spring and convection due to a pressure difference between two spaces, said union comprising a substantially hollow tubular body having a radially extended middle partition of a

1. A union for butting two reused plastic bottles at their mouths to provide a teaching aid for simulating the forming of spring and convection due to a pressure difference between two spaces, said union comprising a substantially hollow tubular body having a radially extended middle partition of a predetermined thickness; said middle partition being provided with two laterally symmetrical through holes, each of which is provided at an axially middle point with an annular rib radially projected toward a center of said through hole, dividing said through hole into a first and a second part opposite to each other, and said first and said second parts are so sized that a suction tube of predetermined dimensions is adapted to insert into these parts; and said tubular body being provided on an inner wall surface at each side of said middle partition with an internal screw thread adapted to engage with an external screw thread provided on the mouth of said plastic bottle.