WO2013005197A2

WO2013005197A2 - Hydrostatic system and corresponding control method

Info

Publication number: WO2013005197A2
Application number: PCT/IB2012/053486
Authority: WO
Inventors: Salvatore ADORISIO; Francesco Anselmo CAVARRETTA
Original assignee: Adotek Engineering Di Ing. Salvatore Adorisio Ditta Individuale
Priority date: 2011-07-06
Filing date: 2012-07-06
Publication date: 2013-01-10
Also published as: ITBO20110402A1; WO2013005197A3

Abstract

A hydrostatic system (1) and corresponding control method; the hydrostatic system (1) having a basin (6) filled with a fluid (7), a drive unit (2), a final load (3), and a mechanical assembly (8) set between the drive unit (2) and the final load (3); the mechanical assembly (8) having a mechanism (9) for multiplication of the force, and a floating body (10) with an internal cavity (11) and set within the basin (6); the floating body (10) being connected to a first portion (15) of the mechanism (9); a second portion (16) of the mechanism (13) being designed to drive the final load (3) and being moved by the first portion (15).

Description

"HYDROSTATIC SYSTEM AND CORRESPONDING CONTROL METHOD"

TECHNICAL SECTOR

The present invention relates to a hydrostatic system and method.

PRIOR ART

It is known to exploit the hydrostatic thrust that acts on a body immersed in a fluid for driving a final load, such as an electric generator.

For example, known to the art are hydrostatic systems comprising a plurality of floating bodies, which are connected to the periphery of a wheel mounted so that it can turn about an output shaft of the electric generator, the floating bodies being inflated or deflated so as to cause, under the action of the hydrostatic thrust, rotation of the wheel. Alternatively, it is known to apply a plurality of floating bodies to a conveyor and/or belt that extends along a closed path.

The patent application No. DE202007010685U1 and the patent application No. FR2640325A2 describe hydrostatic systems of the type of the ones described above.

Systems of the type described above present the disadvantage of having low energy efficiency.

DESCRIPTION OF THE INVENTION

The aim of the present invention is to provide a hydrostatic system and method that will enable elimination of the drawback described above and will at the same time be easy and economically advantageous to produce.

According to the present invention a hydrostatic system and method is provided according to what is specified in the annexed claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention^■ will now be described with reference to the annexed drawings, which illustrate a non- limiting example of embodiment thereof, wherein:

- Figure 1 is a schematic lateral view with parts removed for clarity of a hydrostatic system according to the present invention; and

- Figure 2 is a top plan view of the system of Figure 1. PREFERRED EMBODIMENT OF THE INVENTION

In Figures 1 and 2, designated as a whole by 1 is a hydrostatic system comprising a drive unit 2 and an electric generator 3 (illustrated in Figure 2) , which comprises in turn an output shaft 4 mounted so that it can turn about an axis 5. Preferably, the electric generator 3 comprises an asynchronous motor.

According to what is illustrated in the figures, the system 1 comprises a basin 6, for example a well, filled with a fluid 7 (in particular water.) . Preferably, the basin 6 has a depth, namely, the distance between the free surface of the fluid 7 and the bottom of the basin 6, greater than 2 m.~ In particular, the basin 6 has a depth equal to or greater than 5 m .

The system 1 further comprises at least one mechanical assembly 8, which is set between the drive unit 2 and the generator 3 so as to transmit to the generator 3 a twisting moment Mt generated by a force received at input from the drive unit 2. In particular, the system 1 is designed to multiply the hydrostatic thrust Fi that acts on the floating body 10 filled by the drive unit 2.

The mechanical assembly 8 in turn comprises a linkage 9 and a floating body 10, which has an internal cavity 11 and is set inside the basin 6. The cavity 11 is in fluid communication with the drive unit 2 and comprises a valve element 12 to set the cavity 11 in direct communication with the outside world, in particular with the basin 6.

According to what is illustrated in Figure 1, the linkage

9 comprises a lever 13 having a fulcrum 14, the floating body

10 being connected to an application portion 15, and the generator 3 being connected to a resistant portion 16. The fulcrum 14 is set between the application portion 15 and the resistant portion 16. In particular, the distance Ba between the application portion 15 and the fulcrum 14 is equal to or greater than the distance Br between the resistant portion 16 and the fulcrum 14. Preferably, the distance Ba is from two to seven times greater than the distance Br. In particular, the distance Ba is five times the distance Br.

It may be noted that the mechanical assembly 8 further comprises a transmission unit 17 set between the generator 3 and the lever 13. The transmission unit 17 in turn comprises a spring 18, a flywheel 19 fitted around the output shaft 4, and a converter 20, which is set between the spring 18 and the output shaft 4. The flywheel 19 is designed to accumulate kinetic energy and regulate the rotation of the output shaft 4 in a direction W about the axis 5.

According to what is illustrated in Figure 1, the spring 18 is set within a cup- shaped body 22, and the linkage 9 comprises a cable 23 (in particular, a steel cable), which is connected by means of a plate 24 to an end portion 25 of the spring 18. The portion 25 of the spring 18 is mounted translating within the body 22, and the cable 23 is hinged to the plate 24 and to the resistant portion 16.

According to what is illustrated in Figure 1, the converter 20 comprises a wheel 28 and a rack 29 meshed with one another. The rack 29 is connected to the plate 24 and is mounted translating in a reciprocating way along a path A; the wheel 28 is mounted so that it can turn about an axis 33 parallel to the axis 5. The converter 20 further comprises a gear wheel 30 fitted about the output shaft 4. The gear wheel 30 meshes with the wheel 28. Preferably, the wheel 28 is a free wheel and is designed to transmit a twisting moment Mt to the gear wheel 30 only in one direction R- of rotation so that the gear wheel 30 is turned always in the direction W.

Preferably, the drive unit 2 comprises a machine for converting mechanical energy into fluid energy (for example, a hydraulic pump or a pneumatic compressor) and the mechanical assembly 8 comprises a duct 31, which connects, in a known way and is illustrated schematically, the cavity 11 of the floating body 10 to the drive unit 2. Preferably, the lever 13 is at least partially hollow, and the duct 31 is set within the cavity of the lever 13. The drive unit 2 is designed to fill the cavity 11 of the floating body 10 with a fluid 32 having a density different from the density of the fluid 7 contained in the basin 6. According to what is illustrated in Figure 1, the floating body 10 comprises an outer cage 36 and an elastic body 37 set within the cage 36, the elastic body 37 having the cavity 11 and comprising the valve element 12. The cage 36 is connected, in a known way and illustrated schematically, to the lever 13. According to a variant (not illustrated) , the floating body 10 has only one elastic body (for example, just the elastic body 37 without the cage 36) . According to a further variant (not illustrated) , the floating body 10 is made as a rigid body, and the cavity 11 is filled preferably with a gas (for example, the floating body is shaped like a hollow bell) . Preferably, the floating body 10 has a shape with reduced fluid-dynamic resistance.

According to a variant (not illustrated) , the transmission unit 17 comprises a system of pulleys. In other words, the transmission unit 17 is a mechanical device designed to convert a linear motion (the translation of the end portion 25 of the spring 18) into a rotation (of the output shaft 4) .

According to what is illustrated in Figure 1, the transmission unit 17 comprises a blocking element 34, which is designed to regulate the translation of the end portion 25 of the spring 18 from a loading position L to a resting position U, where the spring 18 is substantially unloaded or else applies to the rack 29 a force less than a predetermined value. In particular, the blocking element 34 is designed to regulate the translation of the end portion 25 from the loading position L to the resting position U. Preferably, the blocking element 34 is activated/deactivated via a pneumatic/hydraulic actuator of a known type and not illustrated. According to a variant (not illustrated) , instead of the spring 18, the transmission unit 17 comprises a pneumatic or oleodynamic system, which is designed to absorb energy momentarily under the action of the cable 23 and to transfer it gradually to the output shaft 4 through translation of the rack 29.

According to what is illustrated in Figure 1, the system 1 comprises a pair of basins 6a and 6b, which are parallel to one another, and a pair of mechanical assemblies 8a and 8b substantially specular with respect to one another. The mechanical assembly 8a is set at least in part within the basin 6a; the mechanical assembly 8b is set at least in part within the basin 6b.

It may be noted that the mechanical assembly 8a comprises an idle wheel 35 with axis 38 parallel to the axis 5 and set between the wheel 28a and the gear wheel 30. The wheel 28a is designed to reverse the direction of rotation transmitted by the wheel 28a to the gear wheel 30 so that the output shaft 4 is always turned in the direction .

According to what is illustrated in Figure 2, the system 1 comprises a plurality of mechanical assemblies 8a, which are arranged within the basin 6a, and a plurality of mechanical assemblies 8b, which are arranged within the basin 6b. The mechanical assemblies 8a and 8b are designed to transmit in a reciprocating way a twisting moment Mt to the output shaft 4.

According to a variant (not illustrated) , each lever 13 connected to a respective floating body 10 is set outside the respective basin 6. In other words, each lever 13 is set outside the fluid 7. Preferably according to a variant (not illustrated) , each mechanical assembly 8 is set prevalently outside the fluid 7.

In use, the drive unit 2 fills the cavity 11 with the fluid 32, which has a density different from the density of the fluid 7. According to the solution illustrated in Figure 1, the fluid 32 expands the elastic body 37 of the floating body 10, increasing the volume of water displaced within the basin 6 by the floating body 10. Preferably, the fluid 32 has a density lower than the density of the fluid 7. In particular, the fluid 32 is a gas. For example, approximately 1.2 m³ of air are pumped into the floating body 10.

The floating body 10 is moved in a reciprocating way within the basin 6 along a path D by a resultant force Fr, which is a function both of the weight force Fp of the full floating body 10 and of the hydrostatic thrust Fi . The resultant force Fr acts, through the floating body 10, on the application portion 15 of the lever 13. In particular, the resultant force Fr is transmitted through the linkage 9 to the transmission unit 17. Preferably, the resultant force Fr is multiplied by means of the lever 13 so as to obtain a final force Ff greater than the resultant force Fr. According to what is illustrated in Figure 1, the final force Ff is designed to compress the spring 18. In particular, the lever 13 transmits to the transmission unit 17 a final force Ff , the value of which is determined substantially by the relation

Ff = Fr - ^

Br

where Ba is the distance between the application portion 15 and the fulcrum 14; and

Br is the distance between the resistant portion 16 and the fulcrum 14.

In particular, during the filling step the resultant force Fr pushes the floating body 10 from a bottom position I to a top position S. Simultaneously, the final force Ff loads the spring 18, bringing the plate 24, and consequently the end portion 25 of the spring 18, from the resting position U to the loading position L. In the loading position L, the spring 18 is pack closed. For example, the force Ff is designed to compress the spring 18 for approximately 1 m prior to activation of the blocking element 34.

During the filling step, the free wheel 28 does not transmit a twisting moment Mt to the output shaft 4.

According to a preferred embodiment, the drive unit 2 comprises a compressor, which fills the cavity 11 of the floating body 10 with a gas (for example, air) in a period of time comprised between 5 and 15 s.

Once the free surface of the fluid 7 contained in the basin 6 is substantially reached, the valve element 12 of the floating body 10 is opened so as to cause exit of the fluid 32 contained within the cavity 11. During the emptying step, the resultant force Fr pushes (drops by gravity) the floating body

10 from the top position S to the bottom position I.

Preferably, during the emptying step the spring 18 remains blocked until the floating body 10 reaches the bottom position

I (substantially until the floating body 10 reaches the bottom) . Whilst the floating body 10 translates from the top position S to the bottom position I, the cable 23 goes slack.

When the floating body 10 reaches the bottom position I, the blocking element 34 disengages from the spring 18; then, the spring 18 unloads all its energy on the shaft 47 via the rack

29, which translates upwards. After this step, the cable 23 is again tensioned.

It should be noted that the twisting moment Mt is transmitted through the free wheel 28 to the output shaft 4 of the generator 3 only after release of the spring 18 (i.e., as mentioned previously, substantially until the floating body 10 reaches the bottom) .

According to a preferred embodiment, the cavity 11 of the floating body 10 is filled with a gas, which during the emptying step comes out of the cavity 11 in a time comprised between 0.01 and 3 s.

The system 1 can be driven so as to repeat consecutively a plurality of steps of filling and emptying of the floating body 10.

The flywheel 19 accumulates kinetic energy and enables rotation of the output shaft 4 about the axis 5 to be kept constant during alternation of the application of the twisting moment Mt .

During operation of the system 1, which comprises a plurality of mechanical assemblies 8 (illustrated in Figures 1 and 2), preferably the steps of filling and emptying of the floating body 10 are cadenced so as to have a uniform application of the twisting moment Mt to the output shaft 4.

From what has been set forth so far, it follows that the hydrostatic system 1 of the type described above exploits both the hydrostatic thrust that acts on a floating body 10 and the linkage 9 to increase the value of the force at input to the system 1 used for inflating the floating body 10. In particular, the system 1 of the type described above enables generation of electrical energy by exploiting the amplification by means of a simple machine, such as the lever, of the hydrostatic thrust acting on the floating body 10 and generated by filling of the cavity 11 through the activation unit 2. The hydrostatic system 1 of the type described above enables generation of energy by means of the generator 3 driven by the mechanical assembly 8 and presents an energy efficiency higher than hydrostatic systems of a known type.

Claims

C L A I M S

1. A hydrostatic system;

the hydrostatic system (1) comprising a drive unit (2) , a final load (3), and at least one mechanical assembly (8; 8a; 8b) set between the drive unit (2) and the final load (3) ;

the hydrostatic system (1) having at least one volume (6; 6a; 6b) filled with a first fluid (7) ;

the mechanical assembly (8; 8a; 8b) comprising a mechanism (9) for multiplication of the force, and a floating body (10) , which has an internal cavity (11) , is set within said volume (6; 6a; 6b), and is mounted mobile in a reciprocating way along a first working path (D) ;

the cavity (11) being in fluid communication with the drive unit (2) , which is designed to supply selectively a second fluid (32) within the cavity (11) ;

the floating body (10) being connected to a first portion (15) of the mechanism (9) ;

a second portion (25) of the mechanism (9) being mobile according to said first portion (15) and being designed to drive the final load (3) ;

the mechanism (9) comprising a lever (13), which has the first portion (15) and a third portion (16) , and a unit (18) for storing mechanical energy, in particular a spring (18) ; and

the accumulation unit having said second portion (25) and being set between the lever (13) and the final load (3) ; the hydrostatic system (1) being characterized in that:

A. the outlet portion (25) is connected to the third portion (16) of the lever (13) and is designed to translate along a second working path (A) according to the position of said third portion (16) ;

B. the mechanical assembly (8; 8a; 8b) comprises a transmission unit (17) , which connects said second portion (25) to the output shaft (4);

C. the transmission unit (17) is designed to convert the linear motion of the second portion (25) into a rotary motion of the output shaft (4) ;

D. the transmission unit (17) comprises a blocking element (34) , which is designed to engage the second portion (25) in a working direction; and

E. the blocking element (34) is designed to hinder selectively the displacement of the second portion (25) from a loading position (L) to a resting position (U) .

2. The system according to Claim 1, wherein the storage element (18) comprises a spring of a pneumatic type.

3. The system according to Claim 1 or Claim 2, wherein the lever (13) is set outside the first fluid (7) .

4. The system according to Claim 1 or Claim 2, wherein the lever (13) is set at least in part within the first fluid (7) .

5. The system according to any one of Claims 1 to 4 , wherein the fulcrum (14) of the lever (13) is set between the first and third portions (15, 16) ; a first distance (Ba) between the first portion (15) and the fulcrum (14) being equal to or greater than a second distance (Br) between the third portion (16) and the fulcrum (14) .

6. The system according to Claim 5, wherein the first distance (Ba) is from two to seven times greater than the second distance (Br) ; in particular, the first distance (Ba) being five times greater than the second distance (Br) .

7. The system according to any one of the preceding claims, wherein the final load (3) comprises an electric generator (3) with a shaft (4) mounted so that it can turn about an axis (5) .

8. The system according to any one of the preceding claims, wherein the drive unit (2) comprises a machine for converting mechanical energy into fluid energy; in particular, the second fluid (32) being a gas and the drive unit (2) comprising a compressor.

9. The system according to any one of the preceding claims, wherein the floating body (10) comprises an elastic body (37) .

10. The system according to any one of the preceding claims and comprising two or more mechanical assemblies (8; 8a, 8b) ; in particular, the system (1) comprising two or more volumes (6a, 6b) filled with the first fluid (7) , each volume (6a; 6b) housing at least one respective mechanical assembly (8a; 8b) .

11. A control method of the hydrostatic system (1) according to any one of the preceding claims;

the method comprising:

a step of filling the cavity (11) of the floating body (10) , at least partially and by means of the drive unit (2) ; and

a step of emptying, at least partially, the cavity (11) of the floating body (10) ;

during the filling step and/or the emptying step a resultant force (Fr) acting on the floating body (10) being transmitted to the final load (3) (in particular an electric generator (3)) through the mechanism (9); the resultant force (Fr) being a function both of the weight force (Fp) and of the hydrostatic thrust (Fi) that act on the floating body (10) .