JPH018206Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a safety device for preventing the screw shaft from rotating on its own in a piano chair in which the seat plate is raised and lowered by the rotation of a screw shaft to adjust its height.

The inventor of this invention previously devised a lifting device for a piano chair in which the seat plate of the piano chair is raised and lowered by turning a screw shaft provided on its underside.
This is disclosed in Japanese Utility Model Application Publication No. 164655/1983. Its structure is such that a seat plate that is raised and lowered relative to the frame is placed above the frame fixed to the legs, and a screw shaft is rotatably supported on the underside of the frame while restricting its axial movement. The center parts of the opening/closing rods are screwed into threads formed on the shafts in opposite directions, respectively, and the outer ends (lower ends) of the lifting arms whose inner ends (upper ends) are pivotally connected to both ends of the opening/closing rods The outer end (upper end) of a support arm is fixed to a support shaft rotatably installed at both ends of the underframe, and intersects with the elevating arm in an X shape and is pivotally connected at the intersection. The inner end (lower end) of the support arm is fixed to a sliding rod which is supported by the underframe below the opening/closing rod so as to be slidable in the inner and outer directions, and has a screw shaft. When the knob fixed to the lever is turned to the left or right, the opening/closing rod moves to widen or narrow the intersection of the lifting arm and the support arm, and the seat plate is lowered or raised. There is. In chairs like this, where the seat is raised and lowered by turning the screw shaft, it is unlikely that the screw shaft will rotate by itself, but in order to be on the safe side, the present invention is designed to raise and lower the seat after adjusting the height of the seat. In this case, a means is provided to restrain the screw shaft so that it cannot rotate, so that it is securely fixed, so that even if the screw shaft tries to turn due to, for example, the amount of weight applied to the seat plate, the rotation will be prevented. This is what I did.

Embodiments of the present invention will be described below with reference to the drawings.

A seat plate 3 that is raised and lowered relative to the underframe 2 fixed to the leg 1 is arranged above the frame 2, and a screw shaft 4 is mounted on the lower surface of the seat plate 3 so as to be rotatable while restraining movement in the axial direction. , 6, and the center parts of the opening/closing rods 9, 9 are screwed into mutually opposite threaded parts 7, 8 carved in the screw shaft 4, respectively, and the upper end of the lifting arm 10 is attached to both ends of the opening/closing rod 9. The lower end of the lifting arm 10 is fixed to a support shaft 11 rotatably installed on both ends of the underframe 2.
A support arm 12 that intersects with the lifting arm 10 in an X shape and is pivotally connected at the intersection thereof has its upper end pivotally connected to the seat plate 3, and its lower end is a sliding arm that is supported by the underframe 2 so as to be slidable in the inward and outward directions. It is fixed to the rod 13. The above is the same structure as the conventional piano chair, but in the present invention, one knob 14 is not fixed to the screw shaft 4,
It is fitted so as to be slidable in the axial direction, one end of which is received by the protrusion 15 of the screw shaft 4, and is constantly biased in the direction of removal by a compression coil spring 16 wound around the screw shaft 4. An annular stop 17 through which a compression coil spring 16 passes is fixed to the lower surface of the seat plate 3, and an appropriate number of pawls 18 are arranged at equal intervals around the circumference on the end surface of the annular stop 17 (the screw shaft end, that is, the end surface on the knob fitting side). It is set in. Reference numeral 19 denotes a cylindrical shaft interposed between the compression coil spring 16 and the knob 14 and fitted onto the screw shaft 4 so as to be slidable in the axial direction, and the cylindrical shaft 1 faces the end surface of the annular stop 17.
Claws 21 that can engage with the claws 18 are provided on the 20 surface of the tip flange 9 at equal intervals around the circumference. A long groove 22 provided long in the axial direction on the cylinder shaft 19
A protrusion 23 protruding from the screw shaft 4 is fitted into the screw shaft 4.
At the fitting portion where the knob 14 fits into the screw shaft 4,
The screw shaft 4 is provided with a square groove 26 in which the circumferential groove 25 is connected to the axial groove 24, and a protrusion 28 provided on the surface of the fitting hole 27 of the knob 14 can freely slide into the square groove 26. is fitted. The compression coil spring 16 acts on the knob 14 via the cylindrical shaft 19 in a direction in which the pawl 21 of the cylindrical shaft 19 is disengaged from the pawl 18 of the annular stop 17;
When the protrusion 28 of the knob 14 is fitted into the axial groove 24 and the claw 18 and the claw 21 are disengaged, when the knob 14 is turned, the screw shaft also rotates with the seat plate 3.
You can freely adjust the height of the knob 14.
Push the cylindrical shaft 19 against the compression coil spring 16 with
The knob 14 is at the position where the claw 21 engages with the claw 18.
The protrusion 28 can be fitted into the circumferential groove 25 and the knob 14 can be rotated relative to the screw shaft.
5, the engagement between the claws 18 and 21 is maintained.

With the above structure, when the claws 18 and 21 are not engaged as shown in FIG. 2 or 5, when the knob 14 is turned, the screw shaft 4 also turns, so the seat plate 3 cannot be raised or lowered. However, when the knob 14 is pressed and the claws 18 and 21 are engaged as shown in Fig. 6, the knob 14 can be turned with respect to the screw shaft 4. 19 is prevented from retreating, so that the screw shaft 4 cannot turn by itself. In this way, the present invention allows the seat plate to be raised and lowered and to ensure safety with simple operations.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a front cross-sectional view of the entire piano chair, FIG. 2 is a partially cutaway front view of the main parts of the present invention, and FIG. 3 is a cross-sectional view of the end of the screw shaft. FIG. 4 is a sectional view taken along the line AA in FIG. 3, and FIGS. 5 to 7 are sectional views for explaining the operation of essential parts. 3... Seat plate, 4... Screw shaft, 14... Knob, 1
6... Compression coil spring, 17... Annular stop, 18
...Claw, 19...Cylinder shaft, 20...Tip collar, 21
...Claw, 22...Long groove, 23...Protrusion, 24...
Axial groove, 25...circumferential groove, 26...shaped groove,
27... Fitting hole, 28... Protrusion.

Claims (1)

[Scope of utility model registration request] In a piano chair in which the seat plate located above the underframe is raised and lowered by the rotation of a screw shaft provided on the underside of the seat plate, an appropriate number of claws are attached to one end of the screw shaft around the circumference. Cylindrical shafts provided at equal intervals are fitted so as to be slidable in the axial direction but not rotatable, and then a knob that abuts the proximal end surface of the cylinder shaft is fitted so as to be slidable in the axial direction, and is wound around the threaded shaft. An annular stop having a pawl that engages with the pawl when the cylindrical shaft is slid together with the knob against a compression coil spring is fixed to the seat plate. A safety device for a piano chair in which a seat plate is raised and lowered by rotation of a screw shaft, characterized in that a knob is fitted on a screw shaft so that the knob can be rotated relative to one another.