The present invention is about a pump for adjusting the vertical position of a chair seat, suitable in particular for being installed on chairs used in hairdresser or beauty salons to seat comfortably the customers.

It is known that, in hairdresser's salons, chairs having a pump between the base and the sitting plane to adjust the seat's height and thus the position of the person seated thereon are used.

The pump substantially comprises a cylindrical body which bounds an oil volume and which is connected to the base of the chair by a pumping device for sending the oil from the cylindrical body to a chamber when said pumping device is activated by an operating lever, protruding from the cylindrical body in order to be accessible for an operator.

A vertical axis shaft is placed in the chamber, connected to the bracket which supports the chair seat.

The adjustment of the vertical position of the seat is thus performed by the activation of the lever connected to the pump.

The operator presses the lever with his foot one or more times, with sequential and mutually alternating movements, to gradually dispose step by step the seat at the height which allows him to perform at best the hairstyling, providing at the same time for a comfortable position in front of the mirror to the customer.

If the hairdresser wants to lower the chair when the customer is seated thereon, he maintains the lever constantly pressed downward for a certain time, thus obtaining the descent of the seat.

Once the seat has reached the desired height, it is indispensable to block stably the chair in that position so that, even if the customer makes sudden or sharp movements, the chair remains steady.

This allows the hairdresser to operate in optimal conditions, with the customer's head always at the same initial height from the bearing surface of the chair, thus maintaining a constant reference point.

From this point of view, said aspect assures a uniform and regular hairstyle to the customer.

Different techniques for blocking the chair seat at the desired height are known.

A first device of known type essentially consists in the insertion of the wedge-shaped extremity of a rod connected to the operating lever into a ring, so that the external wall of said ring is expanded, placing close to the internal wall of the shaft enclosing it and connected to the chair seat, thus preventing any movement of said seat.

Another device of known type, more similar to the invention hereby described, comprises a series of leverages and transmissions to block the movement of the shaft, always activated by the lever when it is moved upward.

However, the hereby described blocking systems of a chair seat in the desired vertical position have some acknowledged inconveniences.

The main inconvenience is due to their constructive complexity, determined by the numerous components which have to be mutually connected in different ways, usually by hinged fixing means.

This can be found in particular in the blocking systems provided with leverages, which make excessively complicated especially the pump assembly.

Another inconvenience, also to be found in the blocking systems provided with leverages, consists of wear and failure after some operative cycles of the mechanical parts responsible for the blocking.

The present invention intends to solve the above mentioned inconveniences.

In particular, the main object of the invention is to provide for a pump for adjusting the vertical position of a chair seat which is easier to manufacture with respect to the equivalent pumps of known type, especially regarding to the blocking device of the chair seat in the desired position.

It is a further object of the invention to reduce with respect to the prior art the breakings, and consequently the repairing and replacement interventions, of the parts forming the chair blocking device.

Said objects are attained by a pump for adjusting the vertical position of a chair seat which, according to the contents of the main claim, comprises:

• a pump body, coupled with the base of said chair, in which an oil tank is internally defined;
• pumping means, disposed in said pump body and coupled to an operating lever movable by an operator, able to raise the pressure of said oil inside a chamber made in said pump body;
• a cylinder having a vertical axis, slidingly coupled in said chamber and having an extremity protruding from said pump body coupled with said seat of said chair;
• blocking means for said cylinder, able to bind said seat in the reached position,

Advantageously, the pump of the invention is of easier conception with respect to the prior art, because the blocking device of the chair seat does not have a series of element mutually connected by fixing means of different kind.

In particular, the leverages and the transmissions usually employed in the prior art closest to the object of the invention are eliminated.

More advantageously, the breakings at the blocking device are considerably reduced by the invention, especially with respect to the breakings occurring in the pumps of known type provided with the aforesaid leverages.

As much advantageously, the invention allows to block in a safe and stable way the chair seat in the reached vertical position.

Furthermore advantageously, the pump of the invention allows an efficient and immediate raising of the seat when the operator presses the lever downward.

Further characteristics and features of the invention will be better highlighted in the description of a preferred embodiment of the invention given in an explanatory way, with reference to the figures of the annexed drawings, wherein:

• Figure 1 is an axonometric view of the pump of the invention in a first use configuration;
• Figure 2 is an axonometric view of the pump of Figure 1 in a second use configuration;
• Figure 3 is a longitudinal section of the pump of Figure 2;
• Figure 4 is an axonometric view of an enlarged detail of Figures 1 and 2;
• Figure 4a shows the detail of Figure 4 according to the sectional plane A-A;
• Figure 5 is an axonometric view of another detail of Figures 1 and 2;
• Figure 6 is a longitudinal section of a detail of the configuration shown in Figure 1;
• Figure 7 is a longitudinal section of a detail of the configuration shown in Figure 2; and
• Figure 8 is an axonometric view of a further detail of Figures 1 and 2.

The pump of the invention is shown in Figures 1 and 2, where it is generally indicated with numeral 1, in two different operative configurations.

It is used for the adjustment of the vertical position of the seat S of a chair, of which the base B only, as well as the seat S, is shown for convenience of exposition.

In substance, in Figure 1 the pump 1 of the invention is shown in the well known configuration in which the operating lever 5 is lowered toward the base B of the chair to raise the seat S of the chair.

On the contrary, the subsequent Figure 2 shows the pump 1 of the invention in the configuration in which the operating lever 5 is raised toward the seat S of the chair, to bind it in a stable way in the reached position after the performance of subsequent pumping operations of the type shown in Figure 1, which have taken the seat S at that height.

It is noted that the pump 1 comprises:

• a pump body 2, coupled with the base B of the chair, in which an oil tank 3 is internally defined;
• pumping means, generally indicated with numeral 4, disposed inside the pump body 2 and coupled to an operating lever 5 movable by an operator, used to raise the pressure of the oil inside a chamber 6, visible in Figure 3, made in the pump body 2;
• a cylinder 7 having a vertical axis Y, slidingly coupled inside the chamber 6 and having the extremity 7a, protruding from the pump body 2, coupled with the seat S of the chair;
• blocking means, generally indicated with numeral 8, for the cylinder 7, used to bind the seat S in the reached position.

According to the invention, the blocking means 8 comprise a thrust body 9, visible starting from Figure 3 only, interposed between the internal surface 7b of the cylinder 7 and eccentric means, generally indicated with numeral 10, belonging to the operating lever 5 and able to force the thrust body 9 against the cylinder 7 when the operating lever 5 is brought near to the seat S.

The pumping means 4 comprise a piston 11, partially surrounded by a spring 12 along its length, coupled with a check valve 13 consisting in this case of a little ball disposed at the feeding path 14 of the oil from the tank 3 to the chamber 6.

In Figure 3 it is evidenced that the pumping means 4 are coupled to the operating lever 5 by a shaft 16 disposed in a shaped body 15 which closes at the top the pump body 2, from which protrudes an arm 17 provided with a thrust extremity 17a cooperating with the pumping means 4 when the operating lever 5 is brought near to the base B.

The shaft 16 is generally shown in Figure 4, where the eccentricity of the cylindrical element 18 with respect to said shaft 16 (see the longitudinal axis Z and Z') and the above mentioned arm 17 and thrust extremity 17a are clearly visible.

In such Figure, as well as in the section of Figure 4a, it is evidenced that the eccentric means 10 comprise a cylindrical element 18 obtained in the substantially intermediate position 16a of the shaft 16.

In Figure 3 it is still noted that the shaft 16 is inserted in a first through hole 19, obtained in the shaped body 15 and extending according to a longitudinal axis Z perpendicular to the vertical axis Y of the cylinder 7.

This cylinder 7 is inserted in its turn in a second through hole 20 obtained in the shaped body 15.

The operating lever 5 is coupled at the opposite ends 16b, 16c of the shaft 16 by fixing means, generally indicated with numeral 23 and of known type, consisting for example in this case by a couple of dowels.

The piston 11 is inserted at its turn in a third through hole 24, which has a longitudinal axis Y' parallel to the vertical axis Y of the cylinder 7, obtained in the shaped body 15 from which it protrudes for a portion 11a.

Therefore, the shaped body 15 has the shape shown in Figure 5, in which the three above mentioned through holes 19, 20 and 24 are evidenced.

The thrust extremity 17a of the arm 17 acts on the upper part of the portion 11a of the piston 11 when the operating lever 5 is pressed toward the base B in order to raise the seat S of the chair.

Moreover, Figures 5, 6 and 7 show that the shaped body 15 has a through opening 21 formed at a portion of the wall 15a, which divides the first through hole 19 from the second through hole 20, arranged to house the thrust body 9 in order to dispose it in front of the cylinder 7 and the cylindrical element 18 belonging to the shaft 16.

As it can be noted, the through opening 21 has a cross sectional rectangular profile.

The thrust body 9, already visible in Figure 3, comprises a little plate 22 made of frictional material, preferably but not necessarily bronze, which, together with the material forming the cylinder 7 cooperating therewith, that is chromiumplated and rectified aluminium, forms a coupling between two surfaces which gives a great stability to the blocking of the cylinder 7.

Moreover, the material of the little plate 22 is particularly wear resistant: in fact, from experimental laboratory tests, it was verified that the little plate 22 has a wear of about 0,2 mm after being submitted to about 40.000 thrust cycles, this being an aspect which is a guarantee of extremely high functionality during time.

As it is evidenced in Figure 8, the little plate 22 is provided with a curved wall 22a which is coupled to the external wall 7c of the cylinder 7, and with a linear wall 22b opposed to the curved wall 22a, which delimitates the first through hole 19.

Operatively, the hairdresser who performs the hairstyle of the customer's head raises the seat S of the chair by pressing downward, with repeated but alternating movement of the foot, the operating lever 5, as shown in Figure 1, to take the seat S of the chair to the desired position.

In this stage, the pump 1 works in a well known way for the technician expert in the related field, with the oil flow pushed by the pumping means 4, moved at their turn by the thrust extremity 17a of the arm 17 from the tank 3 to the chamber 6 where the cylinder 7 is raised.

Once the correct position is reached, the operator raises the operating lever 5 toward the seat S of the chair for blocking it there, as shown in Figure 2.

The blocking is obtained by the rotation in anticlockwise direction of the shaft 16, which disposes the cylindrical element 18 eccentric therewith against the little plate 22, thus being pressed against the external wall 7c of the cylinder 7.

In fact, in such position, the little plate 22, thanks to the characteristics of the material from which it is composed, maintains steady in position the cylinder 7, preventing it from any oscillation and displacement along its vertical axis Y.

The pump of the invention is extremely easy to manufacture, because the leverages and the fixing means used to connect them, usually employed in the equivalent pumps of known type, are removed.

Moreover, the blocking action is particularly efficient, because of the utilization of materials with high friction factor forming the thrust body which acts on the cylinder connected to the chair seat.

The action of the blocking means is fluid and immediate, avoiding to raise the operating lever several times to obtain an efficient brake for the movable cylinder.

On the basis of the aforesaid description, it should be understood that the pump for adjusting the vertical position of a chair seat according to the invention achieves all the previously mentioned objects.

Modifications to the pump of the invention could be introduced in the production stage, consisting for example in a different shape of the operating lever or the pumping means which send the oil in the chamber where the cylinder connected to the chair seat slides.

Moreover, in other embodiments the material used to make the thrust body could be different from the above described one, without reducing the advantages provided by the present patent.

All the described and cited embodiments, even if not shown in the annexed drawings, when they should fall within the scope of protection of the following claims, should be considered protected by the present patent.