EP3677775B1 - Micro-hydro generation plant - Google Patents

Description

Technical field of the invention

The present invention relates to the general field of pressurizing a hydraulic fluid. It aims more precisely at a high-performance, small-scale hydraulic power plant, hereinafter called a micropower plant.

State of the art

In the field of pressurizing a hydraulic fluid, it is known to mainly use gear pumps or piston pumps.

Gear pumps, which use the combined profile of two gears to transfer and increase the pressure of a fluid, are simple in design and easy to maintain, and their cost price is relatively low. Besides, gear pumps are of two types: external gear pump or internal gear pumps.

The first type of gear pump is easy to use but has the disadvantage of having a rather low flow rate. Indeed, the space available between the face of the teeth of the gear wheels and the body of the pump tends to increase as the external gear pump wears, which has the consequence of increasing volumetric losses and 'weaken the volumetric efficiency of such a pump.

The second type of gear pumps has the advantage of being very quiet and having better volumetric efficiency, especially at low rotation speeds. However, this type of gear pump generally has the disadvantage of having rather high energy consumption.

Piston pumps offer the best volumetric efficiency but are the most expensive.

Gear pumps are advantageously used to deliver a high flow rate while piston pumps are more used to obtain high pressure. However, to obtain a high flow rate or high pressure, it is generally necessary to use bulky pumps, see US 6454543 B1 with the state of the art.

The document US 6454543 B1 does not disclose the particular arrangement of the pumps and reservoir of the present invention.

Summary of the invention

The aim of the present invention is to propose a hydraulic power plant having high performance, namely: the highest possible hydraulic flow, a pressure as high as possible while consuming the minimum amount of energy, said central unit being small in size so that it can be easily implemented on mobile devices.

In accordance with the invention, a microhydraulic power plant is therefore proposed for pressurizing a fluid as described in claim 1.

The motor is advantageously either an electric motor associated with a reduction gear and means for reversing the electric current to reverse the direction of rotation of said motor, or a pneumatic motor associated with means for reversing the input/output circuit of said hydraulic motor to reverse the direction of rotation of said motor.

• un réservoir contenant le fluide, et
• une plaque de fermeture dudit réservoir, le moteur, les deux pompes à piston, la pompe à engrenages et la roue libre étant alors directement ou indirectement solidaires de ladite plaque de fermeture du réservoir et disposés à l'intérieur de ce dernier.

The micropower plant includes:

• a reservoir containing the fluid, and
• a closing plate of said tank, the motor, the two piston pumps, the gear pump and the free wheel then being directly or indirectly secured to said closing plate of the tank and arranged inside the latter.

The plate advantageously includes a pressurized fluid outlet, corresponding to the outlet of the micropower plant, and a fluid return to the tank.

The plate further comprises a first pipe provided with a non-return valve and connecting the delivery of the gear pump and the outlet of pressurized fluid, and a second pipe connecting the delivery of all of the two piston pumps and said first pipe downstream of said non-return valve.

The direction of rotation of the motor is preferably reversed when the micropower plant reaches a set value Vc.

The setpoint value Vc is advantageously a determined pressure level of the fluid at the outlet of the micropower plant or an absorption of the current determined at the terminals of the motor.

Brief description of the figures

• [Fig 1] est une vue en coupe longitudinale de la centrale hydraulique selon l'invention,
• [Fig 2] est une vue de dessus de la centrale de la figure 1 sans sa plaque supérieure,
• [Fig 3] est une vue en coupe horizontale éclatée de la centrale de la figure 1 sans son réservoir de fluide.

Other advantages and characteristics will become clearer from the description which follows of a mode of execution of the invention with reference to the appended figures in which:

• [ Figure 1 ] is a longitudinal sectional view of the hydraulic power plant according to the invention,
• [ Figure 2 ] is a top view of the power plant figure 1 without its upper plate,
• [ Figure 3 ] is an exploded horizontal sectional view of the power plant of the figure 1 without its fluid reservoir.

Description of embodiments

On the figures 1 to 3 , we have shown the high-performance hydraulic power plant 1 of small dimensions according to the invention, hereinafter called micro power plant 1, the latter being capable of pressurizing a fluid 2, advantageously oil.

• un réservoir 3 contenant un volume de fluide 2,
• une plaque 4 de fermeture dudit réservoir 3,
• un moteur 5 entrainant en rotation un vilebrequin 6 dans un sens de rotation R ou dans le sens opposé R',
• deux pompes à piston 7 disposées en opposition, mises alternativement en mouvement par la rotation dudit vilebrequin 6 et aptes à aspirer du fluide 2 contenu dans le réservoir 3 et à le mettre sous pression,
• une pompe à engrenages 8 disposée dans le prolongement dudit vilebrequin 6 et apte à aspirer du fluide 2 contenu dans le réservoir 3 et à le mettre sous pression, et
• une roue libre 9 solidaire de l'extrémité libre dudit vilebrequin 6, disposée entre lesdites pompes à pistons 7 et la pompe à engrenages 8, et apte à entraîner en rotation l'arbre de sortie 81 de ladite pompe à engrenages 8 lorsque le vilebrequin 6 tourne dans le sens R et à ne pas entraîner en rotation ledit arbre de sortie 81 lorsque ledit vilebrequin 6 tourne dans le sens R' opposé.

Thus, the micropower plant 1 advantageously comprises at least:

• a reservoir 3 containing a volume of fluid 2,
• a plate 4 for closing said tank 3,
• a motor 5 rotating a crankshaft 6 in a direction of rotation R or in the opposite direction R',
• two piston pumps 7 arranged in opposition, alternately set in motion by the rotation of said crankshaft 6 and capable of sucking up fluid 2 contained in the tank 3 and putting it under pressure,
• a gear pump 8 arranged in the extension of said crankshaft 6 and capable of sucking up fluid 2 contained in the tank 3 and putting it under pressure, and
• a free wheel 9 secured to the free end of said crankshaft 6, disposed between said piston pumps 7 and the gear pump 8, and capable of rotating the output shaft 81 of said gear pump 8 when the crankshaft 6 rotates in the direction R and not to rotate said output shaft 81 when said crankshaft 6 rotates in the opposite direction R'.

We understand here that the expression "a gear pump 8 arranged in the extension of said crankshaft 6" defines the relative position of the gear pump (8) relative to the crankshaft (6), that is to say that the micropower plant (1) comprises one after the other a motor (5), a crankshaft (6) then a gear pump (8).

All of the constituent elements of the micropower plant 1, namely: the motor 5, the two piston pumps 7, the gear pump 8 and the free wheel 9, are directly or indirectly integral with said plate 4 for closing the tank 3 and arranged inside the latter.

In the embodiment described, the micropower plant 1 is associated with a hydraulic installation, not shown, operating in a closed circuit. Consequently, the plate 4 advantageously comprises an outlet 41 of fluid 2 under pressure, corresponding to the outlet 10 of fluid 2 under pressure of the micropower plant 1, and a return 42 of fluid 2 in the tank 3. The plate 4 further comprises a first pipe 43 advantageously provided with a non-return valve 44 and connecting the delivery of the gear pump 8 and said outlet 41 of fluid 2 under pressure, and a second pipe 45 connecting the delivery of the assembly of the two piston pumps 7 and said first pipe 43 downstream of said non-return valve 44.

However, the micropower plant 1 could also be associated with an external reservoir of more or less large capacity and with a hydraulic installation not operating in a closed circuit, without departing from the scope of the present invention; the plate 4 will then be modified and will in particular not include a fluid return 2.

The motor 5, which is associated with reversing means to reverse its direction of rotation, is either an electric motor associated with a reduction gear 51 and means for reversing the electric current, not shown in the figures, to reverse the direction rotation of said motor 5, or according to an embodiment not shown, a pneumatic motor associated with means for inverting the input/output circuit of said pneumatic motor to reverse the direction of rotation of said motor 5. The inversion means are therefore either means of reversing the electric current, or means of reversing the input/output circuit.

Thus, with this configuration of the micropower plant 1, when the motor 5 drives the crankshaft 6 in the direction of rotation R, the free wheel 9 rotates the output shaft 81 of said gear pump 8. The latter then sucks in fluid 2 contained in the tank 3 and delivers it in the first pipe 43 to the outlet 41 of fluid 2 of the plate 4, the fluid 2 passing through a non-return valve 44. Simultaneously, the assembly of the two piston pumps 7 sucks fluid 2 contained in the reservoir 3 and delivers it into the second pipe 45 up to the outlet 41 of fluid 2 of the plate 4 via the first pipe 43. With the direction of rotation R, at the outlet 41 of fluid 2 of the plate 4, a high flow rate of fluid 2 is obtained at low pressure.

Here, “low pressure” means a pressure of fluid 2 less than 70 bars and “high pressure” means a pressure of fluid 2 greater than 300 bars. Likewise, here we designate by "low flow" a flow rate of fluid 2 less than 0.5 l/min (liter per minute) and by "high flow rate" a flow rate of fluid 2 greater than 2 l/min.

When the microcentral 1 reaches a set value Vc, the direction of rotation of the motor 5 is reversed and the latter then drives the crankshaft 6 in the direction of rotation R', the freewheel 9 no longer rotates the shaft. outlet 81 of said gear pump 8 which no longer sucks up fluid 2 contained in tank 3. However, all of the two piston pumps 7 still suck up fluid 2 contained in tank 3 and discharge it into the second pipe 45 to the outlet 41 of fluid 2 from plate 4 via the first pipe 43. However, in order to prevent the fluid 2 under pressure supplied by all of the two piston pumps 7 from entering the gear pump 8 , a non-return valve 44 blocks access to the latter. With the direction of rotation R', at the outlet 41 of fluid 2 of the plate 4, a low flow rate of fluid 2 is obtained at high pressure.

The setpoint value Vc can be, for example, at a determined pressure level of the fluid 2 at the outlet 10 of the micropower plant 1 or an absorption of the current determined at the terminals of the electric motor 5.

We therefore understand that, in the microhydraulic power plant according to the invention, the specific freewheel 9 and the reversal of the direction of rotation allow the motor 5, depending on its direction of rotation, to drive either the piston pumps 7 alone, or the piston pumps 7 and the gear pump 8 in particular to have a high flow rate.

Thus, at a determined motor torque, the gear pump 8 will be disengaged by reversing the direction of rotation of the motor 5, the piston pumps 7 having no direction of rotation for their operation, the flow of fluid delivered by the micro hydraulic power plant 1 according to the invention then goes from a high high at low pressure to a low flow rate, that of the piston pumps 7 alone, a high pressure, and this for the same engine torque as in the first direction of rotation .

The micropower plant 1 may include more than two piston pumps 7 without departing from the scope of the present invention.

Those skilled in the art will have no difficulty in implementing and dimensioning the elements necessary for the proper functioning of the micropower plant 1 such as, for example, strainers for sucking up the fluid 2 contained in the tank 3, pipes for connecting the delivery of the various pumps to the first and second pipes 43,45 or even ball or needle bearings and supports.

We understand that thus configured the micropower plant 1 according to the invention makes it possible to obtain high performance while being particularly compact.

• un débit de fluide 2 à 70 bars de l'ordre de 2,5 l/mn, lorsque le moteur tourne dans le sens R,
• un débit de fluide 2 à 500 bars de l'ordre de 0,5 l/mn, lorsque le moteur tourne dans le sens R'.

According to a non-limiting sizing example, a micropower station 1 equipped with a motor 5 with two directions of rotation, either pneumatic of 360 W at 6 bars of air, or electric of 400 W at 24 V, makes it possible to obtain the following characteristics :

• a fluid flow rate of 2 to 70 bars of the order of 2.5 l/min, when the motor turns in direction R,
• a fluid flow rate 2 at 500 bars of the order of 0.5 l/min, when the motor turns in direction R'.

The micropower plant 1 according to the invention finds a particular application in the locking or clamping of workpieces by hydraulic cylinders where a rapid approach at low pressure and a blocking at high pressure are needed.

Finally, it goes without saying that the examples of micropower plant 1 conforming to the invention which have just been described are only particular illustrations, in no way limiting the invention.

Claims (6)

1. A micro-hydro generation plant (1) for pressurising a fluid (2), including at least:

   - one motor (5) associated with reversing means for reversing the direction of rotation of said motor (5) and driving in rotation a crankshaft (6) in a direction of rotation R or in the opposite direction R',

   - two piston pumps (7) arranged opposite to each other, alternately moved by the rotation of said crankshaft (6) and capable of drawing fluid (2) and discharging it under pressure towards the outlet (10) of the micro-generation plant (1),

   - a gear pump (8) arranged in the extension of said crankshaft (6) and capable of drawing fluid (2) and discharging it under pressure towards the outlet (10) of the micro-generation plant (1), and

   - a free wheel (9) secured to the free end of said crankshaft (6), arranged between said piston pumps (7) and the gear pump (8), and capable of driving in rotation the output shaft (81) of said gear pump (8) when the crankshaft (6) rotates in the direction R and of not driving in rotation said output shaft (81) when said crankshaft (6) rotates in the opposite direction R',

   - a reservoir (3) containing the fluid (2), and

   - a plate (4) for closing said reservoir (3),

   the motor (5), the two piston pumps (7), the gear pump (8) and the free wheel (9) then being directly or indirectly secured to said plate (4) for closing the reservoir (3) and arranged inside the latter.
2. The micro-generation plant (1) according to claim 1, characterised in that the motor (5) is either an electric motor associated with a reduction gear (51) and means for reversing the electric current to reverse the direction of rotation of said motor (5), or a pneumatic motor associated with means for reversing the input/output circuit of said hydraulic motor to reverse the direction of rotation of said motor (5).
3. The micro-generation plant (1) according to any one of claims 1 or 2, characterised in that the plate (4) includes an outlet (41) of pressurised fluid (2), corresponding to the outlet (10) of the micro-generation plant (1), and a return (42) of fluid (2) into the reservoir (3).
4. The micro-generation plant (1) according to claim 3, characterised in that the plate (4) includes a first pipe (43) provided with a check valve (44) and linking the discharge of the gear pump (8) and the outlet (41) of pressurised fluid (2), and a second pipe (45) linking the discharge of all two piston pumps (7) and said first pipe (43) downstream of said check valve (44).
5. The micro-generation plant (1) according to any one of claims 1 to 4, characterised in that the direction of rotation of the motor (5) is reversed when the micro-generation plant (1) reaches a setpoint value Vc.
6. The micro-generation plant (1) according to claim 5, characterised in that the setpoint value Vc is a determined pressure level of the fluid (2) at the outlet (10) of the micro-generation plant (1) or an absorption of the current determined at the terminals of the motor (5).

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