Acoustic insulator applicable in particular to hydraulic passenger and/or freight elevator pumps

Abstract: Acoustic insulator applicable in particular to hydraulic passenger and/or freight elevator pumps consisting of a shaped shell (12) which encloses at least two sides of the motor & pump unit (10) immersed in an oil bath. Said shell is made up of one fluid proof double-walled plastic structure or more forming one or more chambers previously or periodically filled with air. The shell (12) is fixed with preferably plastic clips (18) to the brackets (20) which support the motor & pump unit (10) and is partially immersed in the operating fluid which entirely covers the motor & pump unit.

Description: The present invention relates to an acoustic insulator applicable in particular to hydraulic passenger and/or freight elevator pumps. Known equipment for the lifting of persons, universally known by the term 'elevators', can be divided in two types substantially different from the construction viewpoint. Besides conventional elevators in which the car is moved by steel cables connected to a winch moved by a ratiomotor, equivalent equipment of the hydraulic type has been spreading. As known, in said hydraulic equipment vertical movement of the car is provided by hydraulic cylinders connected to the car directly or through cables. This type of equipment has found ever greater application, especially because it does not require transmissions and optionally a power unit and associated winch located on the top floor which, for this purpose, must have a bearing slab of adequate size to support high weights and stresses. Among the basic members making up a hydraulic elevator the motor & pump unit which drives the cylinder or cylinders is of fundamental importance. A drawback still unresolved of this type of elevator is however the noise which the motor & pump unit produces and which often tends to exceed the tolerance threshold and can reach levels on the order of 70-85dB (decibels) with certain pressures. This drawback is accented by the fact that the motor & pump unit is arranged in a bath of a fluid such as oil in a metal containment structure which acts as a resonance box, increasing the amplitude of the sound emitted and thus amplifying the noise in conformity with the known principles of acoustic boxes. Various attempts have been made to overcome this drawback, such as for example covering the inside or outside of the metal containment structure with so-called sound deadening materials. With these materials absorption is provided partly in the pores and partly in the fibres making up the sound deadening material which is made to vibrate by the incidental sound waves. The results however have proved satisfactory only for insulating coverings of great density and thickness and whose installation is very costly. Even with these coverings however the drawback correlated with the acoustic insulation is not radically solved, or at least not for acceptable periods of time; indeed, due to their composition, the sound deadening elements used tend to absorb the fluid in which the motor & pump unit is immersed, resulting in progressive filling of the honeycomb cells and thus substantially reducing the sound deadening effect. Another and more serious drawback is that the sound deadening material used, in addition to deteriorating, progressively leaves particles of substance which contaminate the fluid, necessitating periodic replacement thereof. Considerable quantities of fluid are involved such as oil (200÷400 litres for each replacement) which must be replaced and disposed of. The resulting costs, only for change and disposal of the used fluid, are thus quite high. To these costs must be added the not negligible ones of labour. External insulation of the containment structure of the motor & pump unit could solve the problem of noise and fluid contamination but with this solution it would be necessary to equip the installation with a heat exchanger because external insulation does not allow normal heat exchange with the environment as would be necessary to maintain operating fluid temperature with in acceptable limits. But recourse to a heat exchanger involves a considerable increase in the cost of the installation and consequently cannot be proposed. US-A-3,723,027 discloses an acoustic insulator applicable to the motor-pump unit of hydraulic elevators consisting of a shell enclosing the pump-motor unit constructed as an open box made of metal coated with foam rubber or other sound absorbing material and having the open side facing downwards. The shell can be partially enclosed into a similar box having larger dimensions and its open side at the top. By the disclosed acoustic insulator only a partial reduction of the noise could be at most achieved. The purpose of the present invention is to overcome the above mentioned drawbacks. More specifically, the purpose of the present invention is to provide a covering applicable to the hydraulic motor & pump unit of passenger and/or freight elevators which would ensure excellent soundproofing, not require frequent replacement of the soundproofing material and not influence the average life of the operating fluid. Another purpose of the present invention is to provide a covering of the above type which would be easy to produce and not involve a substantial increase in initial and/or maintenance costs. In accordance with the present invention these and other purposes are achieved by the features in the characterizing part of claim 1. Particular embodiments of the invention are set forth in dependent claims 2 to 9. The insulating covering of the present invention is basically characterized in that it consists of an elastic structure enclosing on two sides and at the bottom the motor & pump unit and is structured in the form of a shell provided with one or more chambers filled initially or periodically with air, said chambers being sealed and proof against the operating fluid. The structure which encloses the motor & pump unit can be in the form of a shell shaped in advance or at the time of use. The thickness of the chambers can be uniform or variable. The functional and construction characteristics of the insulating covering of the present invention will be further clarified by the following description given with reference to the annexed drawings which show a preferred and nonlimiting form of embodiment of the present invention and wherein: FIG. 1 shows a schematic side view of the motor & pump unit substantially contained in the soundproofing covering, FIG. 2 shows a schematic front view of the motor & pump unit and associated covering of FIG. 1, and FIG. 3 shows a schematic plan view of the motor & pump unit and associated covering of the above FIGS. With reference to the above FIGS. the hydraulic motor & pump unit for passenger and/or freight elevators indicated as a whole by reference number 10 is contained in an elastic structure 12 in the form of a shaped shell. Said motor & pump unit 10 and associated shell 12 are arranged in a preferably metal contained, not illustrated in the FIGS. The shell 12 encloses the motor & pump unit 10 below, extends laterally thereto and upward to constitute the side walls 14, 14' and displays, in accordance with a preferred form of embodiment, a removable front bulkhead (16) designed to cover the front side of the unit 10 and connectable by known means to the shell 12. Said shell 12 is open at the top and back end. The shell 12 is appropriately constrained, e.g. by plastic clips 18, to the top end of the brackets 20 fastened to the container and which support the motor & pump unit 10. There is present in the container up to a predetermined level the operating fluid. The quantity of fluid is such as to cover the unit 10 and almost completely cover the shell 12. To attenuate considerably the vibrations resulting from activation of the motor & pump unit 10, amplified by the metal container enclosing it, the shell 12 consists generally of a double fluid proof plastic partition which forms fluid proof chambers having limited thickness. Said chambers are filled initially and/or periodically or continually with air. The conformation of the shell 12 can of course be such as to allow the formation of independent air chambers with different capacities. In addition, the shell 12 can comprise a supporting frame so as to remain adequately spaced, hence insulated, from the motor & pump unit 10 which, when the installation is in use, develops and tends to transmit considerable noise to the outside. The elastic structure 12 is of plastic such as polyethylene, ABS resin, polypropylene, polystyrene, PVC, etc. The covering of the present invention can also consist of one or more elastic structures shaped in a connectable manner and provided with multiple honeycomb cells previously and definitively filled with air. The presence of one or more air chambers enclosing even partially the unit 10 brings a substantial reduction of the noise which, on average, is reduced by approximately 5dB to 10dB (A) compared to the conditions of use of the equipment without any provision and at least equal in effectiveness to that achieved by using conventional soundproofing systems of equivalent size. The advantages from a noise insulation viewpoint are necessarily perceptible in direct proportion to the pressure applied to the operating fluid. An insulating shell having the above described structured, in addition to providing the basic result set forth above, provides another appreciable advantage in that the sound waves produced by the motor & pump unit 10 during operation can expand, using the operating fluid as the continuous transmission medium, only towards the open parts of the shell, thus maintaining the speed of propagation of the medium itself. In all other directions the sound waves, when encountering the covering containing air, change speed, overlying out of phase the waves of the first type. Under these conditions there is a further lowering of the noise threshold owing to the cancelling out of the frequencies of opposite sign. As may be seen from the foregoing, the multiple advantages achieved by the covering of the present invention are evident. The insulating covering of the present invention considerably lowers the noise which the motor & pump unit of hydraulic passenger and/or freight elevators conventionally transmit to the outside. It does not require costly or complicated insulating structures or such that they must be frequently replaced. The same is true for the operating fluid which is kept unimpaired and is not affected by contamination since the plastic material making up the covering is unaffected by time, is not absorbent and does not leave particles which could mix with the fluid. It should be noted that the insulating covering in question, thanks to the intrinsic characteristics of the material used, i.e. plastic, draws and retains electronically all of any solid particles dispersed in the operating fluid, thus performing an effective cleaning action of the fluid. Although the invention has been described in conjunction with a specific embodiment it is evident that many alternatives and variations will be apparent to those skilled in the art in light of the foregoing description. For example, the covering could be provided in a single piece and/or substantially enclose all sides of the motor & pump unit. The covering could present a structure such as to allow differentiated filling as regards segments or quantity of air or equivalent fluid. Any multiple segments constituting the covering could also be designed for systematic filling with air during operation of the motor & pump unit. In addition, although a system of connection and constraint of the covering to the supporting brackets by plastic clips is preferred, the use of other analogous means of connection to said brackets or other components is not excluded.

Claims: An acoustic insulator applied to the motor & pump unit (10) of hydraulic passenger and/or freight elevators and inserted in a container containing a fluid covering said units, said insulator comprising an elastic structure (12) partially enclosing the motor & pump unit (10) and structured in the form of a shell, characterized in that the shell (12) is provided with one or more chambers filled initially, periodically or continuously with air; said chambers being sealed and proof against the operating fluid; and said shell (12) encloses the bottom of the motor & pump unit (10), extends laterally to constitutes the side walls (14,14') and is open at the top and back ends. The acoustic insulator according to claim 1, wherein the thickness of the chambers is variable. Acoustic insulator in accordance with any of the above claims characterized in that it comprises a removable front bulkhead (16) connected with the remaining structure. Acoustic insulator in accordance with any of the above claims characterized in that it is constrained by clips (18) or equivalent devices to brackets (20) fastened to the container and supporting the motor & pump unit (10). Acoustic insulator in accordance with any of the above claims characterized in that the elastic structure (12) is of plastic material. Acoustic insulator in accordance with any of the above claims characterized in that the shell 12 is formed of a double fluid proof plastic partition forming fluid proof chambers. Acoustic insulator in accordance with any of the above claims characterized in that the chambers have different capacities. Acoustic insulator in accordance with any of the above claims characterized in that the shell 12 comprises a supporting frame. Acoustic insulator in accordance with any of the above claims characterized in that it consists of one or more shaped and mated elastic structures provided with multiple honeycomb cells previously and definitively filled with air.

Inventors: MARTINI ANGELO, MARTINI, ANGELO
Applicants: GMV MARTINI SPA, GMV MARTINI S.P.A.
Application year: 1992
Main classification: B66B9
IPC codes: B66B9, F04C29