Platform rocking chair springs

Claim 2

Spring means for mounting a chair seat on a platform to function as a platform rocking chair, said spring means comprising: a pair of substantially flat fiber-reinforced plastic springs having a lengthwise fiber-reinforcing component of 50-95% and a crosswise reinforcing component of at least 5%, brackets for fixing one end of each spring to a side of the platform and the other end centrally to a side of the seat box or other lateral support for the chair seat such that the springs provide the sole support for the chair seat, each of the flat springs having an effective free length of 6-20 cm, a width at least four times its thickness and a compressive strength of at least 350,000 kPa, a flexural strength of at least 350,000 kPa and a flexural modulus of 13 to 55 × 10 6 kPa in the lengthwise direction, the center of the effective free length of each spring being closer to the floor than to the upper surface of the chair seat.

Claim 3

Spring means as defined in claim 1 wherein the reinforcing fibers comprise at least 30% by volume of each flat spring.

Claim 4

Spring means as defined in claim 2 wherein the reinforcing fibers comprise continuous glass filaments.

Claim 5

Spring means as defined in claim 1 wherein the effective free length of each spring is 8-12 cm.

Claim 6

A platform rocking chair incorporating spring means as defined in claim 1.

Claim 7

A platform rocking chair as defined in claim 5 including a swivel mechanism.

Claim 8

Spring means for mounting a chair seat on a platform to function as a platform rocking chair, said spring means comprising: a pair of substantially straight flat fiber-reinforced plastic springs having a lengthwise fiber-reinforcing component of 50-95% and a crosswise reinforcing component of at least 5%, brackets for fixing one end of each spring to a side of the platform and the other end centrally to a side of the seat box or other lateral support for the chair seat such that the springs provide the sole support for the chair seat, each of the flat springs having an effective free length of 6-20 cm, a width at least four times its thickness and a compressive strength of at least 350,000 kPa, a flexural strength of at least 350,000 kPa and a flexural modulus of 13 to 55 × 10 6 kPa in the lengthwise direction, the center of the effective free length of each spring being closer to the floor than to the upper surface of the chair seat, and a pair of bumpers fixed either to the platform or to a lateral support for the chair seat, each extending across the rear of one of the springs, which bumpers are contacted by the springs when the chair seat is rocked backward to increase the effective stiffness of the springs and inhibit excessive rearward rocking movement.

Claim 9

Spring means for mounting a chair seat on a platform to function as a platform rocking chair, said spring means comprising: a pair of substantially straight flat fiber-reinforced plastic springs having a lengthwise fiber-reinforcing component of 50-95% and a crosswise reinforcing component of at least 5%, brackets for fixing one end of each spring to a side of the platform and the other end centrally to a side of the seat box or other lateral support for the chair seat such that the springs provide the sole support for the chair seat, each of the flat springs having an effective free length of 6-20 cm, a width at least four times its thickness and a compressive strength of at least 350,000 kPa, a flexural strength of at least 350,000 kPa and a flexural modulus of 13 to 55 × 10 6 kPa in the lengthwise direction, the center of the effective free length of each spring being closer to the floor than to the upper surface of the chair seat, and a pair of bumpers fixed either to the platform or to a lateral support for the chair seat, each extending across the rear of one of the springs, which bumpers are contacted by the springs when the chair seat is rocked backward to increase the effective stiffness of the springs and inhibit excessive rearward rocking movement.

Claim 10

Spring means as defined in claim 7 including a second pair of bumpers fixed to extend across the fore of the springs, which bumpers are contacted by the springs when the chair seat is rocked forward to increase the effective stiffness of the springs and inhibit excessive forward rocking movement.

Claim 11

Spring means as defined in claim 7 wherein the bumpers are positioned to allow the chair to move through 10-20% of its maximum rocking path without contacting the bumpers.