EP0050465B1

EP0050465B1 - A height control mechanism for a chair, table or the like

Info

Publication number: EP0050465B1
Application number: EP19810304764
Authority: EP
Inventors: Kazutoshi Ogiso; Kazuo Nakamura
Original assignee: Kayaba Industry Co Ltd; Yanagisawa Seiki Seisakusho KK
Current assignee: Yanagisawa Seiki Seisakusho KK; KYB Corp
Priority date: 1980-10-17
Filing date: 1981-10-13
Publication date: 1985-03-27
Also published as: JPS646764B2; EP0050465A1; DE3169577D1; JPS5769811A

Description

The present invention relates to a height control mechanism for a chair, table or the like. In particular it relates to such a height control mechanism in which height adjustment is provided by the action of fluid pressure in a cylinder on a piston in the cylinder.
One such height control mechanism is disclosed in GB-A-1 514188 in which a chair or table equipped with a height support column of fluid pressure expansion type includes a control lever for height adjustment by opening a pressure release valve. The control lever has a pivot hole and is retained by a horizontal pivot inserted through the pivot hole and into a bracket protruding from the support column or from under the seat.
In this arrangement, the control lever has to be inserted from one direction and it is necessary to insert a small pivot and to contrive a means for retaining the pivot. In addition to these problems in fitting and removing the lever, since a pivot hole is formed in the lever, stress will be concentrated at the lower or upper portion around the pivot hole, the lever therefore being liable to break at that point.
Apart from this arrangement utilising a pivot hole and a pivot, a snap-fitting method for retaining the control lever is disclosed in GB-A-1 510 028. In this arrangement, a piston is slidably provided in a cylinder, and a communicating valve is provided in a hollow piston rod connected to the piston. The communicating valve is operated externally by a control lever and a push rod. The push rod is connected with the control lever, with the tip of the push rod movably engaged with a given portion of the control level, and in this case, a snap spherical surface, snap ring groove, or similar allows the tip of the push rod to be correctly engaged with the control lever, the snap fitting being formed at the tip of the control lever. The control lever can then be inserted through a single opening provided in the piston rod, being held so as to allow an upward tilting operation. Thus, relatively intricate assembly is required for the snap engagement structure. Also, since the control lever can be operated only in one direction (which is also the case with the above-mentioned pivotal fitting method) the operator may not readily know the operating direction. If he operates the lever forcibly in the wrong direction, the lever may be bent or broken.
US-A-2 505 100. discloses a height control mechanism for a chair, table or the like, the mechanism comprising a height-adustable supporting column having a cylinder containing working fluid and a piston rod slidable within the cylinder, a cylindrical wall member forming part of the column which is movable for height adjustment and having two openings on opposite sides of the wall member, a control lever retained in the openings of the wall member by retaining means and arranged upon actuation thereof to depress the end of a push rod slidable within the column which push rod actuates a communicating valve between two fluid chambers in the cylinder to vary the position of the piston rod relative to the cylinder and thereby adjust the height of the column. In the specific arrangement disclosed, the control lever or rod is attached to a circular ring positioned just under the seat. Lugs limit the direction of movement of the ring and therefore of the control rod. The retaining means is in the form of further lugs on the control rod preventing it from sliding out of the openings. The use of these further lugs on the control rod prevents it from being readily insertable and removable, and therefore assembly is complex and the part cannot be replaced easily. Furthermore, the fact that the rod can only be moved in one direction leads to the same problem as that mentioned previously in relation to the other known arrangements.
The present invention provides a height control mechanism of the type described above in relation to US-A-2 505 100, characterised in that the retaining means comprises either an engagement groove on the control lever receiving the end of the push rod or two engagement grooves on the control lever receiving upper edges of the two openings, the control lever thereby being movable in either upward or downward directions to depress the push rod, and the control lever thereby being readily insertable in the wall member upon assembly firstly through one of the openings, secondly to engage the end of the push rod, and thirdly through the other of the openings, the groove or grooves on the control lever retaining it in position.
Preferred forms of the invention provide mechanisms including a control lever for height adjustment which, overcoming the above disadvantages of the conventional devices, can be operated upwardly and downwardly, inserted easily in position and prevented reliably from slipping out. Depending on the direction of operation, one or other of the openings will act as a fulcrum for the control lever, causing the push rod to be depressed.
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a partially cutaway longitudinal front view showing a height control mechanism which is a preferred embodiment of the present invention; and
Figures 2 to 5 are partially cutaway longitudinal front views of further embodiments.

In describing the embodiments of the present invention, the internal structure and operation of the height control mechanism fluid operating means are not described here in detail since they are similar to that disclosed, for example, in GB-A-1 514 188.
Referring to Figure 1, a cylinder 9 is filled with a working fluid and a piston (not illustrated) slidably provided in the cylinder 9 to separate two working fluid chambers is connected to one end of a piston rod 10, the other end of the piston rod 10 slidably protruding upwards from the end of the cylinder 9. At the tip of the piston rod 10, a thread portion 10a is formed. A cup-shaped cylindrical wall member 11 to be fitted under a seat, table, etc. has a through-hole for the piston rod including a thread portion 11 a having the piston rod 10 fitted detachably thereto as a result of the parts being screwed together. A push rod 12 for operating a communicating valve (not shown) of a communication passage of the piston is inserted at the centre of the piston rod 10, and the head of the push rod 12 protrudes from the end of the piston rod within the inside centre of the cylindrical wall member 11. In the wall of the cylindrical wall member 11, opposing rectangular openings 13a and 13b are provided in line with the push rod 12 at the centre, and a control lever 15 is inserted detachably into these openings 13a and 13b.
The control lever 15 has an engagement groove 14 in the lower surface, for engagement with the head of the push rod 12, and is brought into contact with the upper edges of the openings 13a· and 13b on the upper surface, to allow the control lever 15 to be tilted in either direction, upwardly or downwardly with either of the upper edges of the openings as a fulcrum 13a' or 13b'. For fitting the control lever 15, it is inserted through one of the openings 13a and 13b to the other, to press down the push rod 12 by a taper surface 15a at the tip of the lever 15, the push rod 12 then returning to the position of the engagement groove 14 of the lever 15 to be engaged therewith and so not allowing the lever 15 to slip out. Furthermore, receiving an upwards force from the fluid in the cylinder (not illustrated) or spring force urging the push rod 12 upwardly, the control lever 15 is pressed against the upper edges of the openings 13a and 13b, to complete assembly of the control lever 15 within the mechanism. In this state, the communication passage of the piston section is blocked by the communicating valve, and the height control mechanism is locked in one position.
If the control lever 15 is tilted upwards (in the X direction as shown in Figure 1), the lever tip is tilted to press down the push rod 12 with the upper edge of the opening 13a as the fulcrum 13a', to open the communicating valve of the piston section allowing communication of the working fluid between both fluid chambers. Thus, by making the piston and the piston rod 10 slide, the seat, etc. can be adjusted to any given height, and if the control lever 15 is released, the seat, etc. can be locked and held at a desired position.
Furthermore, should the control lever 15 be instead tilted downwards (in the Y direction) the lever presses down the push rod 12 with the upper edge of the opening 13b as the fulcrum 13b', and the seat, etc. can again be adjusted to any desired given height.
Therefore, if the control lever 15 is tilted in either direction, upwards or downwards, the push 'rod 12 is pressed down, without causing any operational error. The control lever 15 is prevented from slipping out, by the engagement between the head of the push rod 12 and the engagement groove 14, and once it is fitted in place, it cannot slip out. Furthermore, the raising force received by the push rod 12 urges the control lever 15 to the upper edges of both the openings 13a and 13b, for positive location in that state.
As for the pressing force on the control lever 15 in the example of Figure 1, if the communicating valve (not illustrated) of the piston section in the fluid cylinder is of the plunger valve type, the resulting force corresponding to the enclosed fluid pressure acting on the effective pressure receiving area of the valve is transmitted through the push rod 12, and if the communicating valve of the piston section is energized by a stop spring, the protruding force corresponding to the stop spring is arranged to act as the pressing force for prevention of play in the control lever 15. In any case, it is required that the head of the push rod be brought into contact with the engagement groove 14 of the control lever 15 by the pressing force. Therefore, a coil spring 16 can be provided below the control lever 15 inside the cylindrical wall member 11 additionally to provide a pressing force, and in this case, dimension control of the parts can be readily achieved.
Furthermore in the example of Figure 1, the cylindrical wall member 11 provided with the openings 13a and 13b can be readily detached from the piston rod 10. Therefore when it becomes necessary to remove the control lever 15, for example for transporting the chair or for reusing the control lever 15 in the exchange of the fluid cylinder itself, the thread portion 11 a of the cylindrical wall member 11 can be loosened, to release the engagement between the head of the push rod 12 and the engagement groove 14, so as to allow the control lever 15 to be pulled out easily. If there is no such necessity, the piston rod 10 can be formed to reach directly the position corresponding to the portion of the cylindrical wall member 11.
Another embodiment of the present invention is described below with reference to Figure 2. A cylinder 9 filled with a working fluid contains a piston (not illustrated) slidable to separate two fluid chambers, and a piston rod 10 is connected at one end to the piston and protrudes at the other end upwardly from the end of the cylinder 9.
A thread portion 11 a is formed at the tip of the piston rod 10, and at the centre of a cup-shaped cylindrical wall member 17, a through hole is provided for the piston rod 10 including a thread portion 18. Through these thread portions 11a and 18, the cylindrical wall member 17 is detachably fitted to the piston rod 10. The thread portions 11a and 18 may be omitted, in which case the cylindrical wall member 17 will be permanently fixed to the piston rod 10. A push rod 12, for operating a communicating valve in a communication passage of the piston section, is inserted vertically movably at the centre of the piston rod 10, and the upper end protrudes from the end of the piston rod within the cylindrical wall member 17. Furthermore, in the wall of the cylindrical wall member 17, opposing openings 21 and 22 of rectangular or oval holes are provided in line with the push rod 12 at the centre, and a control lever 20 is inserted crosswise through these openings 21 and 22. The control lever 20 has two engagement grooves 19a and 19b in its upper surface, and is formed evenly flat on the lower surface, with a taper surface 20a formed at the lower portion of its tip. The engagement grooves 19a and 19b are engaged with the upper edges of the openings 21 and 22, and the lower surface contacts the top of the push rod 12. Since the engagement grooves 19a and 19b are engaged with the upper edges of the openings 21 and 22, the control lever 20 can be tilted in either direction, upwardly or downwardly with either of the upper edges of the openings as a fulcrum a or b.
If the depth of the engagement grooves 19a and 19b is 1₂, and the clearance between the lower surface of the lever 20 and the lower edges of the openings 21 and 22 is 1₁, then they should be formed to satisfy 1₁ > 1₂. This should also be the case with the mechanism shown in Figure 1.
During assembly, when the control lever 20 is inserted through one of the openings 21 or 22 to the other, the push rod 12 is pressed down by the taper surface 20a at the tip of the lever, and if the lever is pressed in further in this state, with the lower surface of the lever in contact with the push rod 12, the raising force of the push rod 12 makes the engagement grooves 19a and 19b fit in the upper edges of the openings 21 and 22 when the engagement grooves 19a and 19b have become aligned with the openings 21 and 22. Receiving the force from the fluid in the cylinder, specifically pressure acting on the communicating valve (not illustrated) or spring force for raising the push rod 12, the engagement grooves 19a and 19b of the control lever are pressed against the upper edges of both the openings 21 and 22, not allowing the control lever to slip out. Thus, fitting of the control lever 20 can be achieved simply. In this state, the communication passage of the piston section is blocked by the communicating valve, and the mechanism is locked in position.
In order to remove the control lever 20, for example so as to exchange parts, the control lever 20 can be pressed down against the push rod 12 within the range of 1₁, to release the engagement between the engagement grooves 19a and 19b and the upper edges of the openings 21 and 22, and in this state, the lever can be pulled rightwards (with reference to Figure 2) to be pulled out, with the lower surface and the taper surface 20a of the lever 20 sliding along the head of the push rod 12. Therefore, the control lever 20 can be freely and simply fitted and removed, to allow easy exchange, repair, etc. of parts. If the control lever is tilted upwards (in the X direction as shown in Figure 2) the tip of the lever is tilted downwards with the upper edge of the opening 22 as the fulcrum b, to press down the push rod 12, opening the communicating valve of the piston section, thereby allowing the communication of the working fluid between the fluid chambers. Therefore, by making the piston and the piston rod 10 slide, the seat, etc. can be adjusted to a given height. If the control lever 20 is then released, the seat, etc. can be locked and held at a desired position.
Furthermore, should the control lever 20 be instead tilted downwards (in the Y direction), the rear end of the lever 20 is tilted downwards, to press down the push rod 12, and the seat, etc. can be adjusted to a given desired height.
In the above embodiments, the cylindrical wall member is attached to the piston rod. However, in the case of a height control mechanism in which a gas spring device itself is fitted in a supporting column consisting of an inside cylinder and an outside cylinder slidable relative to each other, the control lever can be tiltably fitted to the inside or outside cylinder.
Figures 3 and 4 show preferred embodiments with the control lever fitted to the inside cylinder of the supporting column.
Referring to Figure 3, an inside cylinder 44 is slidably inserted in an outside cylinder 51, to form a support column A. A thread portion 43 is provided at the upper end of a piston rod 42, and is screwed into the centre of a holding plate 45 fixed by welding, etc. to the upper portion of the inside cylinder 44. By adjusting the amount of screwed engagement, the penetration of the piston rod 42 into the cylinder 46 can be selected as desired. Also at the upper portion of the inside cylinder 44, a pair of openings 47a and 47b are provided for insertion of a control lever 48 therethrough. The control lever 48 has an engagement groove 50 formed to be engaged with the head 49 of the push rod, and in the state of engagement, the control lever 48 is normally resiliently pressed against the upper edges of the openings 47a and 47b, receiving the resilient force of the push rod caused by gas reaction. In this state, if the control lever 48 is tilted upwards (in the X direction as shown in Figure 3) the tip of the lever is tilted with the upper edge of the opening 47a as a fulcrum, to press down the push rod 42, opening the valve of the piston, thereby allowing communication of the working fluid between the fluid chambers. Therefore, by making the piston and the piston rod 42 slide, the seat, etc. can be adjusted to a given height. If the control lever 48 is released, the seat, etc. can be locked and held at a desired position.
When the control lever 48 is tilted downwards (in the Y direction as shown in Figure 3), the lever is tilted with the other opening 47b as the fulcrum so as to press down the push rod 49, allowing the seat, etc. to be adjusted to a desired given height.
In Figure 4, the end of a piston rod 42 is not connected with a holding plate 52 by a screw connection as previously described, but held from both sides by snap rings 53, and a control lever 54 is inserted through openings 47a and 47b, while the engagement grooves 55a and 55b formed in the upper surface of the lever 54 are engaged with the upper edges of the openings 47a and 47b respectively. The lower surface of the control lever 54 is even, and the head of the push rod 50 contacts the even surface. An inside cylinder 44a can be straight as illustrated and this (as well as the inside cylinder 44 of Figure 3) has a seat, table or the like mounted on it.
The height adjustable mechanism itself is not limited to the types shown in the above examples. For example, as shown in Figure 5, a piston rod 60 can protrude downwardly from a cylinder 61, and the head of the piston rod 60, interlocked with a valve 63 opening or closing a communication passage 62 in the cylinder, can protrude from the upper end of the cylinder 61, in an inverted cylinder arrangement. In this case, opposing openings 65a and 65b (for a control lever 64) can be formed in a cylindrical wall member 61 a as an extended portion on the upper end of the cylinder 61. The control lever 64 in the example of Figure 5 is fitted and operated in the same way as described in the above examples.
As described above, embodiments of the present invention allow a control lever to be fitted in a height control mechanism by simple operation of inserting the control lever through one opening and into the other. Compared with the pivotal fitting method used hitherto, the present arrangement is simple in structure and allows the lever to be fitted by unskilled personnel. Therefore, the mechanism can be packed compactly with the control lever removed for delivery purposes. Furthermore, once assembled, the control lever can be tilted in either direction, upwardly or downwardly. Whichever way the control lever is operated, the communicating valve in the cylinder will be released. Therefore, it is not necessary for the operator to have to consider which way the lever should be actuated.
In addition, if the cylindrical wall portion is made readily detachable from the piston rod or from the end of the cylinder, as appropriate, the control lever can be easily removed even after it has been installed, for exchange of other parts of the mechanism or for advantageous re-use of it in a new supporting column.

Claims

1. A height control mechanism for a chair, table or the like, the mechanism comprising a height- adjustable supporting column having a cylinder (9, 46, 61) containing working fluid and a piston rod (10, 42, 60) slidable within the cylinder, a cylindrical wall member (11, 17, 44, 61a) forming part of the column which is movable for height adjustment and having two openings (13a, 13b, 21, 22, 47a, 47b, 65a, 65b) on opposite sides of the wall member, a control lever (15, 20, 48, 54, 64) retained in the openings of the wall member by retaining means (14, 19a, 19b, 50, 55a, 55b) and arranged upon actuation thereof to depress the end of a push rod (12, 42, 66) slidable within the column which push rod actuates a communicating valve between two fluid chambers in the cylinder to vary the position of the piston rod relative to the cylinder and thereby adjust the height of the column, characterised in that the retaining means comprises either an engagement groove (14, 50) on the control lever (15, 48, 64) receiving the end of the push rod (12, 42, 66) or two engagement grooves (19a, 19b, 55a, 55b) on the control lever (20, 54) receiving upper edges of the two openings (21, 22, 47a, 47b), the control lever thereby being movable in either upward or downward directions to depress the push rod, and the control lever thereby being readily insertable in the wall member upon assembly firstly through one of the openings, secondly to engage the end of the push rod, and thirdly through the other of the openings, the groove or grooves on the control lever retaining it in position.

2. A height control mechanism according to claim 1, characterised in that the cylindrical wall member (11) is attached to the upper end (10a) of the piston rod (10).

3. A height control mechanism according to claim 2, characterised in that the cylindrical wall member (11) is detachable from the piston rod (10) to aid removal of the control lever (15).

4. A height control mechanism according to claim 1, characterised in that the cylindrical wall member (61a) is formed by an extension part of a housing of the cylinder (61), the piston rod (60) being provided below the cylinder (61) to act on the base of the column.

5. A height control mechanism according to claim 1, characterised in that the supporting column is formed by relatively slidable inside and outside cylinders (44, 51), the cylindrical wall member being formed as part of the inside cylinder (44).

6. A height control mechanism according to claim 1, claim 2, or claim 3, characterised in that the control lever (15) is provided with a tapering surface (15a) at the end for insertion in the openings (13a, 13b).

7. A height control mechanism according to claim 1, claim 2 or claim 3, characterised in that a spring (16) is provided for biassing the control lever (15) away from the push rod (12).