WO1998020223A1

WO1998020223A1 - Piston device

Info

Publication number: WO1998020223A1
Application number: PCT/SE1996/001414
Authority: WO
Inventors: Per-Erik Karlquist
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-10-27
Filing date: 1996-11-01
Publication date: 1998-05-14
Anticipated expiration: 1999-05-01

Abstract

The invention concerns a piston device comprising a cylinder and a piston which is displaceable between a normal position and a tensioned, biased position. In addition, the piston is formed with at least one passage allowing the medium contained in the cylinder to flow between the two chambers positioned on opposite sides of the piston. The passage is designed to allow flow more rapidly in one direction than in the opposite one, for which reason also piston displacements may be effected quicker and easier in one direction than in the opposite one. This feature is made use to effect automatic return of the piston from its tensioned, biased to its normal position, a feature which is useful in many situations, not least to automatically deactivate door stoppers.

Description

PISTON DEVICE

The present invention relates to a piston device comprising a cylinder and a piston, the latter being movable between two end positions, viz. one tensioned or biased position and one normal position, the return of said piston from the tensioned or biased position to the normal position being effected automatically.

Piston devices may be used e.g. as stoppers for displaceable or pivotal objects. Such stoppers are particularly useful in doors to retain the latter in an open position.

Many prior-art types of door stoppers exist. For example, door stoppers are available that jointly with the door springs are positioned on the upper face of the door, as also door stoppers that are disposed centrally on the door, such as hasps or the like. A very common type of door stoppers is disposed at the lower edge of the door. These door stoppers could consist e.g. of a piston device which is arranged to force a rod outwards, said rod pressing against the support underneath the door to block or immobilise the door in its open position. A feature common to most door stoppers of this kind is that they necessitate active deactivating measures. When the door is set in an open position, release of the door stopper is also required in order for the door to be able to return to the close position. In many cases, this is impractical. Not only is it often time-consuming and inconvenient for the person that sets the door in the open position to have to go back to close it behind him but in addition this task is often forgotten, with the result that the door is left open, inviting burglars and other intrusions. Furthermore, from the points of view of energy consumption and heating expenses it is desirable to avoid that doors leading to heated spaces remain in an open position without cause.

In order to solve this problem, it is convenient to use door stoppers of a kind that, following a period of activation, deactivate themselves and automatically resume the non-biased or non-tensioned position. Door stoppers of this kind are known and as a rule they are based on some kind of electronically operated locking means, for example electromagnets. The disadvantages of using door stoppers featuring such automatic position- return facilities are that they are comparatively expensive and therefore are not used in many places, such as in apartment houses, bicycle-storage rooms and similar premises, although door stoppers offering such facilities would be desirable in these places.

One object of the present invention is to provide a piston device the piston of which, from the tensioned or biased position, automatically resumes the normal position while at the same time the device is cheap and easy to manufacture and suitable for use in situations when automatic return is desirable generally and more particularly for use in door stoppers.

The invention concerns a piston device comprising a cylinder and a piston, the latter being displaceable between a normal position and a tensioned, or biased, position. In addition, the piston is provided with at least one passage allowing flow of medium contained in the cylinder between the two chambers positioned on opposite sides of the piston. The passage is designed to ensure that the flow may be more rapid in one direction than in the opposite one, and consequently piston movements in one direction are quicker and easier in one direction than in the opposite one. This feature may be taken advantage of to achieve automatic return of the piston from the tensioned, biased position to the normal position, a feature which is useful in many applica- tions, not least in connection with automatic deactiva- tion of door stoppers.

The invention will be described in more detail in the following by means of one preferred embodiment thereof and with reference to the accompanying drawings, wherein:

Fig. 1 is a perspective view of one embodiment of a piston device in accordance with the present invention, and Fig 2 is a cross-sectional view through the piston device of Fig. 1 as seen in a longitudinal plane containing the piston device axis.

According to one embodiment, the piston device of the present invention comprises, as illustrated in Figs 1 and 2, a piston cylinder 3 and a piston 3. The piston 3 is movable inside the cylinder 4 and in doing so divides the latter into two chambers 1 and 2. The piston supports two rods, a pressure rod 6 and a stop rod 7, both of which protrude from the cylinder 4 and the axes of which essentially coincide with the cylinder axis. The piston is disposed in such a manner that the pressure rod 6 is turned towards the chamber 1 whereas the stop rod 7 is turned towards the chamber 2. The ends of the cylinder are closed; more precisely, chamber 1, from which the pressure rod 6 projects so as to protrude beyond the cylinder, is closed by means of a lid 12, and chamber 2, from which the stop rod 7 projects so as to protrude beyond the cylinder, is closed by means of a guide means 13, the latter also stabilising and guiding the stop rod 7. Also, seals are provided in the cylinder about the protruding rods in the areas of their exit from the cylinder. Consequently, the cylinder sealingly encloses the interior volume. A seal 22 also seals the piston against the cylinder wall, keeping the two chambers separated from one another. In addition, the piston is provided with two transfer channels forming passages between the two chambers 1, 2. One channel 9 is narrower than the other channel 8. In accordance with the embodiment shown herein, the wider channel is formed with a nonreturn valve 11 preventing flow from chamber 1 to chamber 2 but allowing flow in the opposite direc- tion. In addition, chamber 2 houses a compression spring 5 which is tensioned as the piston is being depressed via the pressure shaft 6 and which then exerts a pressure on the piston, tending to return the latter to its previously assumed, normal position. Finally, the cylinder wall is formed with a by-pass channel 10 having two mouths, which are spaced apart in the longitudinal direction of the cylinder. The positions of the mouths are chosen to ensure that when the piston assumes its tensioned, biased position, both mouths debouch into the chamber 1 whereas in at least one intermediate position between the normal position and the tensioned, biased piston position they debouch on opposite sides of the piston, i.e. one into chamber 1 and the other one into chamber 2. The cylinder volume contains a liquid or gaseous medium, preferably a non-compressible medium, such as e.g. oil.

At its upper end the pressure rod 6 is provided with a pressure plate 14 or similar means to facilitate the pushing-down of the pressure rod 6 into the cyl- inder. The lower end of the stop rod 7 preferably is provided with a bottom plate 17 to increase the friction between the stop rod and the support, thus reducing the force by which the stop rod must be pressed against the support in order to prevent it from slipping thereon. Advantageously, the outwardly directed face of the bottom plate may be covered with a high-friction material, such as a rubber mat. Preferably also, the lower end of the stop rod 6 is fitted intermediate the bottom plate 17 and the stop rod with a movable foot member 16 which for example could be of less diameter size than the stop rod and be displaceable in the axial direction of the stop rod inside a bore formed therein. The foot member displacement range comprises a position of maximum depression wherein the bottom plate, owing to its larger diameter size in comparison with that of the bore inside the stop rod, prevents further depression of the foot member into the stop rod bore. Alternatively, this end position may be obtained by configuring the bore to a smaller depth than the length of the movable foot member. A protruding stop means 20, for instance, which is attached to the stop rod and which is arranged for sliding movement inside a slide groove 19 formed in the movable foot member 16 stops the latter in the maximum position of protrusion thereof. The movable foot member thus is prevented from being displaced further outwards than is allowed by the length of penetration of the protruding stop means 20 into the slide groove 19. The slide groove 19 and the stop means 20 thus could also serve as end-position stop means, in which position the movable foot member has a maximum penetration into the bore. The bore advantageously is formed with a means acting to urge the movable foot member away from the stop rod 7, such as a compression spring 18.

In addition, the piston device preferably is provided with some type of mechanical locking means 15 arranged to lock the piston in the tensioned, biased position thereof, thus neutralising, i.e. overriding the automatic return feature of the piston.

An attachment means 21 advantageously is provided on the side face of the cylinder 4 allowing the piston device to be fastened on a door or the like. In accordance with the present embodiment the attachment means 21 comprises an attachment plate which is secured to the cylinder and which is provided with apertures allowing it to be secured to an external object by means of screws, bolts and other suitable fasteners.

When the piston device is used as e.g. a door stopper, the pressure shaft is exposed to pressure as a result of the pressure exerted on the pressure plate 14. On account of this pressure, which is transferred to the piston, the latter is displaced from the normal position to the tensioned, biased position against the action of the spring on the piston, while at the same time the stop rod 7 is pushed out of the cylinder at the opposite cylinder end and its bottom plate 17, on the movable foot member 16, is pressed against the support and thus locks the door in position. As a result of this ten- sioning the volume of chamber 2 is reduced whereas the volume of chamber 1 increases correspondingly. The medium contained in the cylinder thus flows from chamber 2 to chamber 1 through the two transfer channels 8, 9, until the piston reaches the tensioned, biased position. The piston remains in this position until the pressure on the pressure shaft 6 ceases. In the tensioned, biased position, the spring exerts pressure on the piston, with the result that medium starts to flow back from chamber 1 to chamber 2, when the pressure on the pressure shaft 6 ceases. However, medium will flow through the narrower transfer channel 9 only, because of the provision in the other, wider transfer channel of a nonreturn valve 11. As a result, medium will flow back into chamber 2 at a lower speed, for which reason some time will elapse before the pushed-out stop shaft is retracted and as a result thereof the door is allowed to close. When the door is at a predetermined point on its travel back from the tensioned, biased position to the normal position, the by-pass channel does, however, offer yet another flow path possibility for the transfer of medium from chamber 2 to chamber 1. This possibility presents itself when the mouths of the by-pass channel 10, instead of both debouching into chamber 1 as is the case in the tensioned, biased position, debouch on opposite sides of the piston. This arrangement enhances a rapid return of the medium, which may be an advantage, not least because it eliminates the risk that on account of the di in- ishing spring force the piston will stop in an intermediate position before reaching the normal position. Owing to the compression spring 18, the bottom plate of the movable foot member 16 will press against the support also for a while after the initiation of the piston return motion. The mechanical catch 15 may be used to lock the piston in the tensioned, biased, door- retaining position, thus overriding the automatic piston-return feature. This possibility may be of interest whenever it is desired to keep the door open for a prolonged period of time, for example in connection with removal activities.

It should be pointed out, however, that the above- described embodiment of the invention is but one example thereof. A number of modifications are possible, such as utilising the gravitational force instead of spring force, to position the spring 5 on the opposite side of the piston, to use the piston device for other purposes than as a door stopper, to increase the number of by- pass channels, to eliminate the by-pass channel altogether, to configure and dimension the component parts differently, and so on. These and other equivalent varieties of the invention are intended to be within the scope of the invention as the latter is defined in the appended claims.

Claims

1. A piston device for automatically resetting to a normal position from a tensioned, biased position, comprising a cylinder (4) and a piston (3) , c h a r a ct e r i s e d in that the piston (3) separates two chambers (1, 2) inside the cylinder (4) and is formed with at least one transfer channel (8, 9) constructed to allow gaseous or liquid medium contained in the cylinder (4) to be transferred more rapidly between the separated chambers (1, 2) when the piston (3) is moved to the tensioned, biased position than when it is moved to the normal position.

2. A piston device as claimed in claim 1, c h a r a c t e r i s e d in that the piston device is provided with a spring (5) , said spring being tensioned in response to the piston (3) being moved to its tensioned, biased position, and operative to urge the piston (3) back to the normal position upon cease of a force acting to bring about the tensioning.

3. A piston device as claimed in claim 1, c h a r a c t e r i s e d in that the piston (3) is provided with two transfer channels (8, 9), one narrower (9) and one wider (8), said wider channel (8) being fitted with a nonreturn valve (11), whereby flow may take place by way of this channel (8) only when the piston (5) is moved to the tensioned, biased position.

4. A piston device as claimed in claim 1, c h a r a c t e r i s e d in that the piston (3) is provided with a stop rod (7), which protrudes beyond the cylinder (4) and which is attached to the piston (3), said rod (7) being pushed in a direction outwardly of the cylinder (4) when the piston is moved to the tensioned, biased position.

5. A piston device as claimed in claim 4, c h a r a c t e r i s e d in that the piston device is a door stopper arranged to automatically return from the door-stopping tensioned, biased position.

6. A piston device as claimed in claim 4, c h a r a c t e r i s e d in that the piston (3) is provided with a pressure rod (14) which protrudes beyond the cylinder (4), said pressure rod (14) being attached to the piston (3), whereby the application of pressure against the pressure rod (14) urges the piston (3) to the tensioned, biased position.

7. A piston device as claimed in claim 1, c h a r a c t e r i s e d in that the cylinder (4) has a by-pass channel (10) all the mouths of which debouch into one only of the chambers (1, 2) in the tensioned, biased position of the piston (3) and which interconnects the two chambers (1, 2) in at least one intermediate position of the piston (3) between the tensioned, biased and the normal positions.

8. A piston device as claimed in claim 4, c h a r a c t e r i s e d in that at its end protruding beyond the cylinder (4), the stop rod (7) is provided with a movable foot member (16) which is displaceable in the axial direction of the stop rod (7) between two end positions .

9. A piston device as claimed in claim 1, c h a r a c t e r i s e d in that it is provided with a mechanical locking mechanism (15) adapted to lock the piston (3) in the tensioned, biased position thereof, thus preventing the automatic return.