GB2265435A

GB2265435A - Adjustable gas spring

Info

Publication number: GB2265435A
Application number: GB9206531A
Authority: GB
Inventors: John Wang
Original assignee: LEE WANG INDUSTRY Ltd
Current assignee: LEE WANG INDUSTRY Ltd
Priority date: 1992-03-25
Filing date: 1992-03-25
Publication date: 1993-09-29
Anticipated expiration: 2012-03-25
Also published as: GB9206531D0; GB2265435B; DE9204971U1; FR2689950A3

Abstract

A first tubular member (1) with a closed top end slidably receives a second tubular member (2) with lower and upper closed ends, a piston (4) in the second tubular member (2) dividing the latter into upper and lower chambers (24, 25) which are filled with a pressurized gas. The piston rod (3) extends through the upper end of the second tubular member (2) to connect to the closed top end of the first tubular member (1). The piston (4) has a valve (53) which opens upon actuation of a press button (52) provided on the first tubular member (1), and is urged closed by a spring (51) provided on the upper end of the first tubular member. <IMAGE>

Description

A CUSHION DEVICE The invention relates to a cushion device, more particularly to a cushion device which uses a pressurized gas instead of a hydraulic oil to provide better stability than prior art cushions provide.

A prior art cushion device comprises vertical and tubular inner and outer cylinders. The inner cylinder is disposed coaxially in the outer cylinder so as to define an annular space therebetween. A lower fixing element seals the lower ends of the inner and outer cylinders. A piston is disposed movably in the inner cylinder so as to divide the interior of the inner cylinder into a sealed hydraulic inner chamber and a non-hydraulic inner chamber. A piston rod connects the piston to a base assembly and extends through the lower fixing element. A ring seal is disposed movably in the annular space so as to divide the annular space into a sealed hydraulic outer chamber and a non-hydraulic outer chamber. An upper fixing element seals the upper ends of the inner and outer cylinders and has a passage intercommunicating the hydraulic inner and outer chambers.All of the hydraulic inner and outer chambers, as well as the passage, are filled with a hydraulic liquid. A seat structure is carried on the upper fixing element. A hand-operated valve is mounted on the upper fixing element and is selectively operated to open or close the passage. A resilient body is disposed within the non-hydraulic outer chamber so as to bias the ring seal to move toward the upper fixing element.

When the valve is operated to open the passage, i.e. , when a downward force which is greater than the biasing force of the resilient body is applied to the upper fixing element, the inner and outer cylinders move downward relative to the piston rod so as to impel the liquid to flow from the inner chamber into the hydraulic outer chamber through the passage.

Similarly, when a downward force which is smaller than the biasing force of the resilient body is applied to the upper fixing element, the resilient body pushes the ring seal toward the upper fixing element so as to impel the liquid from the hydraulic outer chamber into the hydraulic inner chamber, thereby moving the inner and outer cylinders upward relative to the piston rod.

The base assembly of a stool has a threaded hole for engaging with the threaded end of the piston. A sleeve is fixed on the base assembly so as to prevent dust from entering the inner and outer cylinders.

Although the height of the stool can be easily adjusted by the above-mentioned cushion device, it has been found that the piston rod has a cross diameter of 8 mm. It is not easy to support a seat structure (P) in a stable position with a piston rod of 8 mm in diameter. To construct a piston rod of larger diameter would increase the cost of production of the cushion device due to the specific complex structure of the piston rod.

A primary feature of the present invention is to provide a cushion device which can provide more stability than the former cushion device while reducing the manufacturing cost thereof.

A second feature of the present invention is to provide a cushion device which uses a pressurized gas which is to be employed in a seat support so as to provide a stable cushioning effect in said seat support.

According to the present invention, the cushion device includes a first tubular member having an upper closed end and a bottom open end and a second closed tubular member which is sleeved into the first tubular member. The second tubular member has a piston therein dividing the former into an upper and lower sealed chamber. The connecting rod of the piston extends through the upper closed end of the second tubular member to connect the sealed top end of the first tubular member. The piston has a valve which opens or closes upon actuation of a press button provided on the closed top end of the first tubular member.

Other features and advantages of the present invention will become more apparent in the following detailed description, including drawings, all of which show a non-limiting form of the present invention, and of which: Figure 1 shows a cushion device of the present invention; Figure 2 shows the cushion device of the present invention in operation; Figure 3 shows the cushion device of the present invention attached to a sleeve of a seat member; Figure 4 shows an enlarged view of a second valve employed in the cushion device of the present invention; and Figure 5 shows an enlarged view of the second valve illustrating the configuration when closing the passage interconnecting the upper and lower portion of an inner cylinder employed in the cushion device of the present invention.

Referring to Figures 1 and 2, a cushion device of the present invention to be used in a chair includes a first tubular member (1) having a lower open end, an upper open end and a first seal member (11) which hermetically seals the upper open end and a second tubular member (2) having a bottom open end which is sealed by a second seal member (21) and a top open end which is sealed by a third seal member (22).

It is important to note that the third seal member (22) is made up of several partitions, each of which has a central opening (23) therethrough, with the lowest partition having a larger central opening (231) as shown in Figure 1, the purpose of which will be described hereinafter.

A piston (4) is slidably provided in the second tubular member (2), dividing the latter into an upper sealed chamber (25) and a lower sealed chamber (24) which is filled by a pressurized gas, such as nitrogen gas. The piston has an axial opening (41) which is sealed by a valve (53) in the lower sealed chamber (24).

In the preferred embodiment, the connecting rod of the piston (4) is formed as a hollow elongated tube (3), the outer diameter of which is exactly the same as that of the opening (23) of the two partitions, thus allowing it to sleeve fittingly through them with a clearance formed between the exterior of the elongated tube (3) and the interior wall of the lowest partition of the third seal member (22). The hollow elongated tube (3) has a radial opening (31) formed through its wall adjacent to the place where a lower bottom end of the same integrally forms with the piston (4). The top end of the elongated tube (3) is securely connected to the first seal member (11) in the first tubular member (1). Thus, the first and second tubular members (1,2) are connected to one another.

A push rod (5) is provided in the elongated tube (3), a bottom end of which is connected to the valve of the piston (4) and a top end of which extends out from the elongated tube (3) to connect with a press button (52). The press button (52) includes a resilient body (51) which biases the push rod (5) in an upright position, pulling the bottom end of the push rod (5) so as to close the valve (53) of the piston (4) in a normal condition.

One thing to note is that the elongated tube (3) and the push rod (5) are made by a known art to seal hermetically in the central opening of the two partitions of the third seal member (22) and the axial opening (41) of the piston (4), respectively. The bottom end of the second tubular member (2) is then secured to a base assembly of a seat support (6), and a seat portion (not shown) can be provided on the top end of the first tubular member (1).

A sleeve member (61) can be provided in the upper portion of the seat support to hold the first tubular member (1) centrally, as shown in Figure 3.

After a person is seated on the seat portion, the press button (52) is pressed downward, pushing the bottom end of the push rod (5) to open the valve (53) of the piston (4). The pressurized gas in the lower sealed chamber (24) will flow into the upper sealed chamber (25) through the axial opening (41) of the piston (4) and the radial opening (31) of the elongated tube (3). The entering gas in the upper sealed chamber (25) continues to push the piston (4) downward until the first tubular member (1) comes to a predetermined height or until it-is deliberately stopped. The valve (53) at this time is closed due to the descent of the piston (4). While the seat portion .moves downward, the person can let go of the press button (52), thereby closing the valve (53), if he or she feels the proper height has been obtained.

When the first tubular member (1) is at the predetermined height, the gas in the upper and lower sealed chambers (24,25) are under the same pressure and the valve (53) is at a closed position The upper chamber (25) has a volume smaller than the lower chamber (24) due to the elongated tube (3), and the gas therein is more compressed when compared to the gas in the lower chamber (24). After a while, if the person wishes to raise the height of the seat portion, he or she only needs to press the push button (52) again, thus opening the valve. The pressurized gas in the upper sealed chamber (25) is compressed by the weight of the seated person so that the gas will flow back into the lower sealed chamber (24) through the radial opening (31) of the elongated tube (3) and the axial opening (41) of the piston.The entering gas-in the lower sealed chamber pushes the piston (4) upward so that the seat portion on the first tubular member (1) will rise to a height higher than the predetermined height. The user can choose the height as in the previous manner.

Referring to Figure 4, in one preferred embodiment,the push rod (5) has a lower enlarged end (55) with a shoulder (56) formed thereon and it is connected to the valve (53). The piston (4) has a narrow section (42) formed in the axial opening (41) of the piston (4), which has an inner diameter larger than that of the enlarged end (55), and a seal member (7) is sleeve around the push rod (5) and is provided in the axial opening (41) of the piston (4) adjacent to the narrow section (42). The seal member (7) has an annular projection (71) whose inner diameter is smaller than the diameter of the enlarged end (55) but is larger than that of the narrow section (42) of the piston (4).When the push rod (5) is pushed downward to open the valve (53), the pressurized gas in the lower chamber (24) will move into the upper chamber (25) through a clearance formed between the outer surface of the enlarged end (55) and the annular projection (71) of the seal member (7) and through a clearance formed between the outer surface of the enlarged end (55) and an inner surface of the narrow section (42). After the valve (53) is closed, as shown in Figure 5, the annular projection (71) serves as an extra seal, preventing the pressurized gas in the upper chamber (25) from flowing back into the lower chamber (24).

An important feature in the seat which uses the cushion device of the present invention is that the seat is stable when compared with the seat which is used in the prior art cushion device. The production cost for the cushion device of the present invention is low, so the seat made with such cushion device is correspondingly cheaper than the prior art cushion device.

Claims

CLm

1. A cushion device including a first tubular member (1) and a second tubular member (2); characterized in that said first tubular member (1) includes a lower open end, an upper open end and a first seal member (11) which hermetically seals said upper open end; said second tubular member (2) includes a bottom open end, a top open end, a second seal member (21) which hermetically seals said bottom open end, and a third seal member (22) which hermetically seals said top open end, said third seal member (22) having a central opening (23)extending therethrough, said top end of said second tubular member (2) being slidably sleeved into said lower open end of said first tubular member (1);; a piston (4) slidably provided in said second tubular member (2) and dividing said second tubular member (2) into an upper portion (25) and a lower portion (24) which is filled with a pressurized gas, said piston (4) having an opening (41) co-axial with the axis of said second tubular member (2); an elongated tube member (3) provided in said first tubular member (1) and having a wall body with an axial opening aligned with said opening (41) of said piston (4), a first end fixed to said first seal member (11) of said first tubular member (1) and a second end extending through said central opening (23) of said third seal member (22) into said second tubular member (2) to connect said piston (4) securely, said wall body having a radial opening formed adjacent to said piston (4) thereof;; a push rod (5) provided in said axial opening of said elongated tube member (3) and having a first end extending out of said axial opening of said elongated tube member (3) and a second end extending through said opening (41) of said piston (4) to connect with a valve (53) provided in said lower portion (24) of said second tubular member (2) to connect said first tubular member (1) to said second tubular member (2); a resilient body (51) provided on said upper end of said first tubular member (1), biasing said push rod (5) upward to enable said valve (53) to close said opening (41) of said piston (4); a press button (52) connected to said first end of said elongated tube member (3) to push said valve (53) to open said opening (41) of said piston (4), allowing the pressurized gas to enter said upper portion (25) of said second tubular member (2); and hermetically sealing and holding members respectively provided in said central opening of said third seal member between said third seal member and said elongated tube member and in said axial opening of said elongated tube member between said pushing rod and said elongated tube member.

2. A cushion device as claimed in Claim 1, characterized in that said third seal member (22) is made up of at least two seal units, each of which has a central opening, said central opening (231) of said seal unit (221) adjacent to said piston (4) having a diameter larger than that of said seal unit away from said piston (4) 3. A cushion device as claimed in Claim 1, characterized in that said bottom end of said second tubular member (2) is sleeved and fixed in a lower end of a third tubular member (6), said third tubular member (6) having an upper end in which a sleeve member (61) is provided to hold said lower end of said first tubular member (1) centrally when the latter (1) is provided in said sleeve member (61).

4. A cushion device as claimed in Claim 1, characterized in that said opening (41) of said piston (4) further includes a section (42) narrower than the remaining section of said opening formed therein away from said valve (53), said push rod (5) including a portion (55) which has a diameter larger than the remaining portion of said push rod (5), said narrow section (42) having an inner diameter larger than the diameter of said portion, a seal member (7) being provided around said push rod (5) in said remaining section and having an inner diameter smaller than the diameter of said portion (55) but larger than the remaining portion of said push rod (5).

13. A cushioning device substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.