Spring floors

Jan. 5, 1960

2,919,476

B. FRITZ

SPRING FLOORS

Filed Aug. 1, 1956

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2,919,476

Patented Jan. 5, I960

United States Patent Office

2,919,476 SPRING FLOORS

Bernhard Fritz, Karlsruhe-Ruppurr, Germany

Application August 1, 1956, Serial No. 601,428 5

Claims priority, application Germany August 6,1955

Claims. (Cl. 20—6)

The invention relates to spring floors wherein a semiresilient floor layer is supported on springs arranged in spaced relationship to one another on a base or foundation.

A semi-resilient floor of a gymnasium, for example, is intended to effect an appreciable conversion of the kinetic energy produced by a user into a stress operation in the floor and thereby to have the effect of preventing or reducing fatigue symptoms and even damage to the user, such as sprains, torn muscles or inflammation of the tendons.

In order to comply with this requirement, downward depressions of the floor should be, as far as possible, of the same size at each point of the floor under the same individual load. In addition, all depressions caused by statically or dynamically acting loads should be of a purely elastic nature, that is to say, should completely disappear again upon the removal of the loads. A further requirement is that the depression which is formed under a local shock load caused for example by people jumping, and which takes the form of an extensive trough of circular ground plan, should have as large a diameter as possible. Depressions which are sharply limited in one or two directions and thereby more local, should be regarded as unfavourable, not only with reference to the stated object, but also because the small radii of deflection curvature should be rejected as deleterious to the preservation and life of the floor and particularly of any surface covering which may be provided.

Moreover, the depressions caused by a person on the floor should not result in any elastic rising of the floor elsewhere, that is to say outside the said circular trough, because a rebounding action, i.e. exactly the opposite of a perpendicularly yielding resilient action, would otherwise occur at such places and would adversely affect any other person jumping there.

Spring floors are known in which the spring suspension is obtained by flexible, bar-shaped supporting members which support various points of the floor in such manner that the elastic sagging of these points imparts resilience to the floor. Since this sagging varies, however, at different places on the floor the desired uniformity of resilience at all places of the floor where people walk can in no way be achieved.

Semi-resilient floors are also known in which a supporting base is on spring supports arranged at spaced intervals from one another. In one of these constructions, the spring supports consist of layered leaf springs and, in another form of construction, of a round plate having laterally projecting turned-down resilient arms.

With these known floors the resilient property which is decisively important for the said purpose is absent because, in the region of the stresses caused by use, the relationship between various loads and the corresponding deflections is a linear relationship giving an almost straight-line graph.

In contrast to this, the present invention has for its main object a semi-resilient floor supported on springs that are so constructed and assembled that at every place on the floor, the depressions caused by kinetic energy loads from persons of very different weights are always practically equal and the relationship between such different loads and the corresponding depressions gives a curved graph.

It is another object of the invention to provide supporting springs in the form of columns of plate springs arranged between a base plate and the floor layer and surrounded by a shield which telescopes with said supports.

A further object of the invention is to provide a tubular spring abutment for each said column in a cover plate of which is guided a bar secured to the bottom, of the floor layer and arranged in the centre of the spring 10 assembly.

Preferably a recoil spring is arranged in order to prevent a hard recoil of the floor layer and to avoid consequent rattling noises.

For perfect distribution of load in all directions the 15 floor layer resting on the supporting springs preferably consists of three tiers of side-by-side elongated wooden boards, planks, beams or the like, intersecting each other at an acute angle of about 60°.

A floor constructed in this manner may also be pro20 vided with a top layer consisting of wood plates such as pressed board or plywood plates and a wear-resistant covering thereon such as linoleum or the like.

An embodiment of the invention is shown in the accompanying drawing in which:

Fig. 1 is a graph showing the relationship between the depth of depression and load in known spring mounted floors and also in a resilient floor constructed according to this invention;

Fig. 2 is a vertical section through a supporting spring 30 constructed according to the invention;

Fig. 3 is a fragmentary ground plan of a floor according to the invention; and

Fig. 4 is a section taken on the line IV—IV of Fig. 3.

In the graph shown in Fig. 1, the straight line 1 shows 35 the relationship of depression to load in the case of the known resiliently mounted floors. For example a person weighing 80 kg. would produce a depression and an amount of spring action twice as great as that produced by a child weighing 40 kg. Therefore, the child would ⁴⁰ not have the same advantages as a person weighing 80 kg. with respect to the relieving of muscular stress when jumping. However, if the spring characteristic has the course as represented by curve 2 shown in Fig. 1, then, with the same conditions for the adult and for the child, a much greater and therefore almost equivalent partial depression of the floor and spring action is obtained. That is to say δ 2&gt;1, while δ 2~Δ is 1.2. Conversely, as best shown in the graph of Fig. 1, the deflection of the spring at about one-half of the weight of an average adult 5θ person (80 lbs.) is about 4.25/5 or about .83 of the deflection at the latter weight.

A spring-mounted floor construction with accurately predictable spring properties which are the same at all parts of the floor and simultaneously adapted to persons 55 of any weight may therefore be considered as a considerable improvement over the already known spring floors.

The semi-resilient floor shown in the drawing comprises a bearing floor or floor layer construction dis_g0 tributing the load in every direction, and supporting springs which elastically support such floor layer with a shock absorbing effect. Each individual spring arrangement comprises a plate spring column or assembly c, the plates or blades of which are arranged between a base plate a and a flanged socket or shield I which is constructed as a spring abutment. On the base plate a there is arranged a tubular spring abutment b through the upper cover plate r of which passes a bar e secured to the base g of the said abutment I at f and arranged in the centre of the spring column c. The lower end of the bar e has a thread h on which there is threaded a lock nut i which in turn supports an annular disc k supporting

2,919,476 ³ a recoil spring d. The socket or shield I simultaneously acts to protect the spring column against the entry of dust or soil. At the places m of the top and bottom supporting members the spring column is mounted in the lower and upper floor structures respectively. 5

The spring supports are selected and assembled so that any desired spring characteristic and therefore any depression characteristic adapted to the weight of the users is achieved according to the curve 2 of Fig. 1. Such a spring arrangement is preferably assembled from a num- 10 ber of dished plate or blade springs which are connected in axial series to form a spring assembly. The plate springs are made of high grade non-fatiguing steel. As shown in Fig. 2, the springs of the assembly vary in thickness and arrangement of spring blade, for example hav- 15 ing single blades at the top and double blades at the bottom, that is to say there is a stratified layer.

The floor layer itself consists of three tiers or laminations of side-by-side elongated members such as joists and boards or planks, the members of each layer inter- 20 secting those of the other layers at an acute angle, for example of 60°, and producing a uniform distribution of load in all directions. The thicker bearing planks or joists n as the lowest layer rest immediately on the supporting springs and are supported thereby at the places 0. 25 The centre board or plank layer p interconnects the planks or joists n. The top board or plank layer q is arranged in close juxtaposition and constructed as an under floor or directly as a floor surface. By such an arrangement a uniform distribution of the load is obtained in the three 30 directions 1, 2, 3 (Fig. 3) both for all points I over a supporting spring column and for all points II between two spring columns.

Thus the main object of the new supporting floor structure is to have a load distributing effect and to adjust 35 itself smoothly to the depressions of the spring columns. These primary depressions which occur owing to the elastic resilience of the springs are always very much greater than the secondary depressions of board or plate layers only, which occur for instance upon a load acting be- 40 tween two supporting columns. Thus the spring properties of the floor are determined in fact only by the supporting spring columns.

If the floor is to receive a resilient covering to prevent wear and tear, such as a cork or rubber covering, it is 45 advisable to dispose on the top board or plank layer q, laid as an under floor without interconnecting grooves and tongues, a further wood layer u in the form of a hard-board or plywood layer and then to cement thereon the linoleum, cork or other material v to prevent wear 50 and tear. The purpose of the compensation layer u is to prevent the occurrence of curves in the under floor q caused by shrinking for example, appearing as irregularities on a thin wear and tear layer.