WO2016190732A1

WO2016190732A1 - Insertable hydraulic turbine for insertion into a fluid conduit

Info

Publication number: WO2016190732A1
Application number: PCT/NL2016/050357
Authority: WO
Inventors: Maarten Adrianus Hubertus HOEDJES; Bernardus Johannes Meijer
Original assignee: Kinetron B.V.
Priority date: 2015-05-27
Filing date: 2016-05-19
Publication date: 2016-12-01
Also published as: NL2014861A; NL2014861B1; ES2663906B1; ES2663906A2; ES2663906R1

Abstract

The invention relates to an insertable hydraulic turbine for insertion into a fluid conduit. The invention also relates to a fluid conduit comprising at least one accommodating space for a turbine according to the invention. The invention further relates to an assembly of such a fluid conduit and such a turbine.

Description

INSERTABLE TURBINE FOR INSERTION INTO A FLUID CONDUIT

The invention relates to an insertable turbine for insertion into a fluid conduit. The invention also relates to a fluid conduit comprising at least one accommodating space for a turbine according to the invention. The invention further relates to an assembly of such a fluid conduit and such a turbine.

Hydraulic turbines are commonly known as rotary engines that convert kinetic and potential energy of water or any other fluid into mechanical work. Hydraulic turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now they are mostly used for electric power generation in various applications, wherein they harness a clean and renewable energy source. One of the more recent applications of the known turbine is the use of said turbine in domestic sanitary installations. In such a domestic sanitary installation, a typical hydraulic turbine comprises a turbine wheel, and a generator, both accommodated by a conduit fitting having a nozzle for guiding water towards the turbine wheel, wherein said conduit fitting can be connected to a fluid conduit. Fluid , such as water, flowing through the conduit causes the turbine wheel to rotate which drives the generator. The (low power) electrical energy which is generated can be used to power (low power) electrical components in the vicinity, such as for example lamps or electronics. An example of such a hydraulic turbine is published in EP 1 147 594, which is hereby incorporated by reference. The known solution is, however, quite laborious, spacious, costly, and hence inefficient to be used. An object of the present invention is to provide an improved turbine which can be used more efficiently.

This object can be achieved by providing a turbine according to the preamble, comprising: at least one turbine wheel, at least one generator connected to said turbine wheel, preferably via a common axis, wherein the generator comprises a rotor and a stator with a field winding which are arranged in a housing, at least one nozzle arranged in said housing for guiding fluid flowing through a fluid conduit towards the turbine wheel, and at least two electrical terminals connected to said field winding, wherein said housing is configured to be partially inserted into a fluid conduit, such that the nozzle and the turbine wheel will be located within said conduit, and such that the electrical terminals will be located outside said conduit. The turbine according to the invention is in particularly a hydraulic turbine, preferably suitable to be used in domestic or corporate (sanitary) installations, and more preferably in liquid conduits, in particular water conduits, used in said installations. Hence, the turbine according to the invention is preferably a low-power turbine, comprising a low-power generator. A low-power generator is typically configured to generate electrical power ranging from several milliwatt to typically 10 watt. Another option is that the turbine according to the invention is used as pneumatic turbine (gas driven turbine), by applying the turbine in a gas conduit though which (compressed) air, natural gas, oxygen, nitrogen, etcetera, could be led.

A major advantage of the turbine according to the invention is that the turbine as such is a complete, ready-to-use product, which includes all required features for autonomous use. The ready-to-use turbine can be plugged (inserted), like a plug, such as a cork, into an opening or accommodating space of and/or hole and/or other interruption made in (a side wall and/or circumferential wall of) a (single) fluid conduit, in particular a water conduit or a gas conduit, after which power can be generated when fluid is forced through the conduit. After insertion the turbine is enclosed and/or surrounded by (a side wall and/or a circumferential wall of) the fluid conduit. Since the turbine is inserted into the fluid conduit, the fluid conduit as such will commonly, and preferably, not be inserted into the turbine. An insertable part of the turbine, which typically includes a bottom part of the housing enclosing the turbine wheel and defining the nozzle, is preferably configured such that it can easily be inserted in the accommodating space of and/or hole made (a side wall and/or circumferential wall of) the fluid conduit. Hence, the maximum outer dimensioning of this insertable part of the turbine is smaller than the maximum inner dimensioning of said accommodating space and/or hole. Preferably, the insertable turbine part has a shape complementary to the shape of the

accommodating space of and/or hole (wall opening) made in the fluid conduit.

Preferably, at least a part of the housing, more preferably an insertable part of the housing, has a substantially rotation symmetrical shape, a substantially cylindrical shape, or a tapered shape. In case the insertable housing part has a tapered shape, this tapered shape is preferably such that the outer dimensioning of the insertable housing part decreases in a direction away from the terminals. The turbine according to the invention can be installed via a one step insertion in a (single) fluid conduit. The direction of insertion of the turbine into the fluid conduit is preferably substantially perpendicular to the flow direction of the fluid through the fluid conduit (and through the turbine). The turbine is preferably configured to be inserted into the fluid conduit by displacement of the turbine in an axial direction of the turbine. The turbine is preferably substantially linearly insertable, hence slideable, into the fluid conduit. Since the turbine according to the invention is preferably inserted into a single fluid conduit, the fluid inlet and the fluid outlet of the turbine are preferably at substantially the same level. An outer wall of the housing of the turbine can be provided with an external thread. This allows the turbine to be screwed into a fluid conduit opening (wall opening of the fluid conduit), resulting - in a relatively firm - screw connection between the fluid conduit and the turbine. Other kinds of external fastening means are also conceivable.

Since the plug-and-play turbine is a completely self-supporting, assembled product, which is ready-to-use and includes all required features for autonomous use, the turbine is (preferably) free of typical fluid conduit fittings or connections. This allows easy and simple insertion of the turbine according to the invention into the fluid conduit wherein only minimum adaptation and/or modification of the fluid conduit is required. No additional conduit fittings or connectors are needed to insert the turbine into the fluid conduit. This reduces the overall dimension of the fluid conduit, and hence to the assembly of the fluid conduit and the turbine (at least partially) inserted thereto, and therefore leads to a less laborious, less spacious, less costly, and hence more efficient solution.

In the context of this patent document, the expression "fluid conduit" has to be understood broadly and includes the non-limitative examples: fluid conduit pipes, fluid conduit fittings (configured to either directly or indirectly mutually connect fluid conduit pipes), other fluid conduit components, and/or complete fluid conduit applications, such as a water tap or a water shower. The fluid conduit encloses one or more fluid channels through which fluid can flow.

In the context of this patent document, the expression "fluid" may relate to a liquid, such as water, and/or may relate to a gas, such as air or natural gas, and/or may relate to a mixture of liquid and gas, such e.g. steam or carbonated liquid.

In case the turbine is inserted into a fluid conduit fitting, an additional advantages is that a relatively simple fluid conduit fitting can be used, which allows the application of a wide range of simple fluid conduit fittings with several types of fluid conduit connections at low costs.

The nozzle makes integral part of the turbine as such, which makes it easy to optimize the design of the nozzle for an optimal turbine yield. This secures that the nozzle and the turbine wheels are always geared to one another, which leads to an optimum performance. In case of a defect, the complete turbine can be removed from the conduit and can be either repaired or replaced by another turbine. This situation prevents that a turbine wheel will be placed in line with a nozzle which is not (perfectly) suitable to co- act with said turbine wheel, and which could lead to poor performances. In

aforementioned turbine known from the prior art, replacement of a turbine wheel by another type of turbine wheel also requires replacement of the nozzle making integral part of the conduit fitting, and thus also requires replacement of the complete conduit fitting which is highly laborious, spacious, costly, and hence leads to an overall inefficient solution. Another important advantage of the turbine according to the invention is that electrical gear, including the electrical terminals and preferably also the field winding, are separated from the wet environment within the conduit by keeping this electrical gear outside the conduit, which is in favour of an easy and safe way to connect electronics outside the fluid conduit while securing a reliable and durable operation of the turbine according to the invention. Hence, after insertion of the turbine into the water conduit, the housing will be partially located within the conduit, or at least within the fluid channel of the fluid conduit, and will also be partially located outside the conduit, or at least outside the fluid channel of the fluid conduit.

In addition to the above, the ready-to-use turbine easily allows optimization of the design and characteristics of the turbine, such as incorporation of additional features and functionality in the turbine, such as a bypass valve or bypass channel. These

adjustments enables customization of the turbine yield, the output power, the pressure drop, and the starting flow rate without having to modify the fluid conduit as such. This enables to have a wide range of characteristics in a fluid conduit without the need for further modification, leading to less need for investments and lower overall costs, especially at small to medium range quantities.

Each electrical terminal may comprise and/or may be formed by an electrical wire. This makes it easier to connect the generator to existing power lines or power wires. The two electrical terminals could for instance form a positive and a negative electrode.

Commonly, the electrical terminals are connected to opposite sides of the field winding. Since the stator is subjected during use to an alternating magnetic field, an alternating current (AC) is generated across the electrical terminals.

The stator and/or field winding may be embedded within the housing. This secures and protects the stator and field winding, and it ensures that the stator and field winding are always located on the same position inside the housing.

The stator or field winding, and preferably both components, are preferably embedded within the housing in a fluid-tight manner. When fluid, such as water, would run through the turbine, it would be unfavourable if this fluid would come in contact with the stator and field winding. By embedding the stator and the winding fluid-tightly in the housing, this can be prevented.

The housing may comprise at least one separation element for separating both the field winding and the electrical terminals from both the rotor and the turbine wheel in a fluid- tight manner. Such element can for instance be formed by a separation cup. This separation element separates the parts of the turbine that come into contact with the fluid from the stator and the parts of the turbine that are electrically wired. Electrical shortages and degradation, in particular failure, of turbine components due to moisture can thereby be prevented.

The part of the housing that is configured to be inserted into the fluid conduit may have a tapered cross-section. A tapered cross-section may improve the sealing effect of the housing in the fluid conduit by insertion of the housing in the conduit. Further insertion of a tapered housing part increases the clamping forces of the conduit on the housing, thereby increasing the sealing of the housing in the conduit. The housing part may therefore have a cork-like or frusto-conical structure.

An outer surface of the housing may be provided with a sealing means for creating a sealing effect between the turbine and the fluid conduit. Such sealing means can for instance be formed by an O-ring, at least partially made from an elastomer, in particular a rubber material (cross-linked material). The sealing means are preferably arranged around or partially embedded in the circumferential wall of the housing. The sealing means thereby prevent fluid to pass between the conduit and the housing to prevent fluid to escape the conduit, and hence to prevent leakage of fluid. Moreover, the sealing means thereby preferably also prevent fluid to undesirably circumvent the turbine, which would be unfavourable for proper operation of the turbine as such. Optionally, separate sealing means, for example separate rubber O-rings or a rubber O-ring and a rubber sleeve, are applied to realize both of aforementioned sealing effects. By partially embedding the sealing means in the circumferential wall of the housing, the sealing means can be easily kept into place. Another advantage is that fluid is thereby prevented from flowing between the sealing means and the circumferential wall. The rotor could be connected to the turbine wheel by means of a common axis

(common axle) to which both components are attached. However, it is also conceivable and commonly also more favourable that the turbine wheel is directly connected to the rotor. A central axle, commonly formed by a rod, may be applied to stabilize the rotation of the turbine wheel and the rotor. The central axle may be either a stationary axle or an axially rotatable axle. Preferably, the complete common axis is substantially held in place by the housing. To this end, both outer ends of the common axis are configured to co-act with the housing of the turbine. The common axis is preferably at least substantially completely enclosed by the housing of the turbine. The axle (or rod) could be supported at its outer ends by the housing by bearings, such that the rod may rotate with limited friction. This makes the generator more efficient. Each bearing may be provided with one or more guiding surfaces for facilitating positioning the rod into the turbine housing and/or - preferably additionally - for facilitating axial rotation the turbine wheel. In this latter case, the guiding surface(s) act(s) as sliding surface(s). The housing may comprises a laterally protruding shoulder configured to be located outside the fluid conduit. The shoulder could for instance form a flange-like rim, extending radially from the circumferential wall of the housing. This shoulder, or rim, could be used to connect the housing to the fluid conduit and could be used to improve the sealing between the two. The shoulder, or rim, could be dimensioned slightly larger compared to the fluid conduit in which the housing is inserted.

The shoulder may comprise at least one accommodating space for a mechanical connection element, such as a screw, to connect the turbine to the fluid conduit. The accommodating space could be formed by at least one hole or opening, which could be provided with thread.

The housing may be a modular housing which comprises a base part and a removable end part, said end part being provided with the at least one nozzle. The end part is for instance an end cap. The end part could further be provided with bearings, to facilitate rotation of the rotor. By removal of the end part from the base part, the interior of the housing becomes accessible. This allows for an easy replacement of different elements, such as the replacement of the end part and/or a (defect) turbine wheel, inside the housing without having to replace the complete turbine, to be able to easily allow modification, in particular customization, of the turbine characteristics. Furthermore, a removable end part also allows easy replacement of the nozzle, as a new nozzle only requires a new end part without replacing the base part. In case the end part would also include a bypass channel also this can be easily modified/customized by placing a different end part with a different bypass channel, or outside diameter (to allow internal leakage) which changes the turbine characteristics.

The base part and the end part can be connected to each other in various ways, such as through a bayonet clasp, snap connection or click connection. Both elements are preferably made of plastic, which is favourable from an economical and practical point of view.

The nozzle may have a curved geometry. The curved geometry may be used to guide fluid to the turbine wheel blades, which are positioned at an angle. This in turn can be used to increase the effective force applied to the blades which leads to an improved rotation of the wheel. The inlet side of the nozzle preferably lies in line with the fluid path of the fluid flowing through the fluid conduit, such that the fluid can easily enter the nozzle.

The diameter of the inlet side of the nozzle may be larger compared to the outlet side of the nozzle, such that it narrows in the direction of the turbine wheel. In this way, the fluid flowing through the nozzle can be accelerated.

The nozzle may be positioned in a plane defined by the turbine wheel. By positioning the nozzle in the same plane as the turbine wheel, fluid flowing through the generator and the fluid conduit follows a substantially linear flow path. This results in less resistance, less energy loss and thereby an improved performance of the turbine.

The turbine may also comprise a bypass valve and/or a bypass channel incorporated within said housing allowing fluid to bypass the turbine wheel. The bypass may be used to prevent a too high pressure difference over the turbine wheel. When the pressure difference in the fluid conduit exceeds the maximum pressure difference the turbine is able to handle, the excess of fluid can flow through the bypass, alleviating the pressure difference over the turbine. This increases, in case of a bypass valve, the safety and durability of the turbine, and enables to have a low pressure drop over a wide flow range and enables to modify/customize the pressure drop in relation to the flow and the related turbine characteristics, i.e. starting flow, by (ex)changing the bypass valve, or parts of the bypass valve, or - if applied - a bypass channel formed in the end cap of the turbine.

The bypass valve is for instance arranged to open after the pressure difference over the turbine exerted by the fluid exceeds a minimum, predetermined pressure. This pre-set pressure difference is a pressure difference at which the turbine is at risk of being damaged, or defined by the required custom turbine characteristics. By opening the valve, the bypass for the fluid becomes available, reducing the pressure difference over the turbine. The bypass valve commonly comprises a mechanical spring to actuate the valve, wherein the spring forces the valve to a closed stated, and wherein the bypass valve will open in case the fluid pressure difference exceeds the counter-pressure of the spring.

The bypass channel is a channel that is always open. Fluid from the fluid conduit flows through both the turbine and the bypass channel. If for instance fluid from the fluid conduit always exerts a pressure difference over the turbine which is too high for the turbine to handle, and/or the turbine characteristics do not meet the demand (i.e. the pressure drop is too high for customer or starting flow is too early), a bypass channel can be set such that the optimal fluid flow through the turbine is achieved. This can be set for instance by changing the dimensions of the bypass channel to vary the pressures experienced by the channel and the turbine, or by reducing the outer diameter of the turbine allowing internal leakage within the turbine housing. The bypass channel can thus be formed within the turbine housing, wherein water can freely flow through said bypass channel. This bypass channel may be positioned at a distance of the turbine wheel, and may be separated from the turbine wheel. It is also conceivable that the bypass channel is formed in between an outer diameter of the turbine wheel and an inner wall (part) of the turbine housing. In an alternative embodiment, the bypass channel is formed as at least one groove applied in an outer wall (part) of the turbine housing. In this latter embodiment, the bypass channel is located outside the turbine housing.

The turbine may be configured to be insertable radially (or laterally) into a wall of a fluid conduit. This way, the axis of the turbine is substantially perpendicular to flow direction of conduit with which turbine is connected. Another advantage is that the turbine may be inserted laterally, perpendicular to the wall of the fluid conduit.

The turbine preferably is free of typical conduit fittings (connectors), such as male and/or female connection parts and/or threaded connection parts configured to be connected to a fluid conduit pipe end. In such way the turbine is an easy-to use construction, that is less laborious, less spacious, less costly, and hence more efficient.

The present invention also relates to a fluid conduit comprising at least one

accommodating space for a turbine according to the invention. The accommodating space has a shape complementary to the shape of the turbine. The fluid conduit may also be provided with sealing means, such as an O-ring, to improve the sealing of the turbine in the accommodating space of the fluid conduit. The invention further relates to an assembly of a fluid conduit and a turbine according to the present invention, wherein the turbine is partially inserted in the accommodating space of the fluid conduit, wherein the nozzle and the turbine wheel are located within said conduit, and wherein the electrical terminals are located outside said conduit. The turbine may be fixed to the fluid conduit, preferably by means of mechanical connection means, such as screws.

The invention will now be elucidated into more detail with reference to the following non-limiting figures, wherein figure 1 shows a cross section of a hydraulic turbine according to a first embodiment of the present invention;

figure 2 shows an exploded view of the hydraulic turbine of figure 1 figure 3 shows a bottom view of a cross-section of a hydraulic turbine according to the first embodiment of the present invention;

figure 4 shows a cross section of a combination of the hydraulic turbine according to the first embodiment and a fluid conduit according to the present invention;

figure 5 shows a cross section of a hydraulic turbine according to a second embodiment according to the present invention;

figure 6 shows the hydraulic turbine of figure 5 in exploded view;

figure 7 shows a bottom view of a cross section of a hydraulic turbine according to a third embodiment of the present invention; and

figure 8 shows an exploded view of a hydraulic turbine according to a third embodiment of the present invention.

Figure 1 shows a cross section of a hydraulic (or pneumatic) turbine (1), comprising a turbine wheel (2) and a generator (3). The generator (3) comprises an axially rotatable magnetic rotor (4) and a stator (5). The turbine wheel (2) and the generator (3) are both arranged in a housing (6). The rotor (4) is arranged rotatably onto a static rod (7), which rod (7) is positioned and locked, and eventually clamped, in between upper and lower bearing surfaces (8a, 8b) of a turbine housing. The stator (5) is arranged stationary in the housing (6). The housing (6) further comprises an inlet nozzle (9) and an outlet opening (10). When a fluid flows from the inlet nozzle (9) to the outlet opening (10) it encounters blades (11) on the turbine wheel (2). The diameter of the inlet nozzle (9) is smaller compared to the outlet opening (10) and is configured to accelerate fluid flowing towards the turbine wheel (2). The fluid will exert a force upon the blades (11) which makes the wheel (2) rotate about the axis (R). This in turn results in a rotating rotor (4) relative to the stationary housing (6), which can be used to generate electricity in a well-known way. The stator ( 5) comprises a field winding (not shown) which is arranged in the axial direction outside the radial projection of the rotor (4), and claw- pole-like magnetoconductive sheets, preferably 8 or 16 sheets, guided axially in the radial projection of the rotor (4), which leads to an efficient generation of electrical power. In figure 1, the housing (6) comprises two housing sections, a base part (12) and an end part (13), which are configured to be connected in a water tight manner to a fluid conduit (17; see figure 4) through a sealing ring (14). The sealing ring (14) is in particular configured to seal a clearance between the housing (6) and an opening or accommodating space of the fluid conduit (17). The two housing sections (12, 13) are for instance coupled via a click-connection. The nozzle (9) and the outlet opening (10) are located on opposite sides of the base part (12). Figure 2 shows an exploded view of the hydraulic turbine (1) of figure 1. Not shown in figure 1 are two electrodes (15) which connect to a connector (16), to transfer electricity generated by the generator (1).

Figure 3 shows a bottom view of the hydraulic turbine (1) of figures 1 and 2.

Figure 4 shows a cross section of a combination of the hydraulic turbine (1) as shown in figures 1-3 and a part of a fluid conduit (17), which may for example constitute a fluid conduit pipe, a fluid conduit fitting, or a complete fluid conduit appliance, such as a water tap. The fluid conduit (17) comprises two fluid channels (18, 19). The first channel (18) connects to the turbine (1), wherein the flow of fluid though the housing (6), from the inlet nozzle (9) to the outlet opening (10) causes the rotor (4) to spin, thereby generating electricity. The second channel (19) is optional and is provided with a valve (20). The valve (20) comprises a spring (21) and a closing element (22).

Initially, the spring (21) exerts a force on the closing element (22), to keep the closing element (22) in a closed state. When the pressure difference over the turbine in the fluid conduit (17) increases to levels which may damage the generator (1), the force exerted by the fluid on the closing element (22) increases to a level in which this force overcomes the force exerted by the spring (21). In that case, the fluid can flow through the (optional) second channel (19) as well as through the first channel (18), thereby reducing the pressure difference exerted by the fluid though the nozzle (9). The bypass valve is furthermore favourable to be able to modify the turbine characteristics, such as the initial flow of the fluid (starting flow), the power output, and the pressure drop. Figure 5 shows a cross section of another assembly of a hydraulic turbine (101) inserted into an accommodating space of a fluid conduit (123). The fluid conduit (123) is schematically shown in this figure and encloses an elongated fluid channel (123a) (of which merely an outer end is shown), and a wall opening (123b) configured to accommodate said turbine (101). The wall opening (123b) is in connection with the fluid channel 123(a). The generator (101) functions like the one as shown in figures 1-4. The hydraulic turbine (101) comprises a axially rotatable turbine wheel (102) and a generator (103). The generator (103) comprises a rotor (104) and a stator (105). The turbine wheel (102) and the generator (103) are both arranged in a housing (106). Both the turbine wheel (102) and the rotor (104) are rotatably arranged onto a centrally located stationary rod (107), which is mounted between two locking holes (108a, 108b) of the turbine housing which lock the rod (107) in axial direction to prevent clearance or play of the rod (107). The stator (105) is arranged stationary in the housing (106). The housing (106) further comprises an inlet nozzle (109) and an outlet opening (110). When a fluid flows from the inlet nozzle (109) to the outlet opening (110) it encounters blades (111) on the turbine wheel (102). The inlet nozzle (109) is configured to accelerate the fluid, in particular water, flowing towards the turbine wheel (102) which increases the rotation speed of the turbine wheel (102) and hence the power output of the turbine (101). , wherein the fluid will exert a force upon the blades (111) which makes the wheel (102) rotate about the axis (R). This in turn results in a rotating rotor (104) relative to the stationary housing (106), which can be used to generate electricity in a well-known way. Also in this embodiment, the stator ( 5) comprises or may comprise a field winding (not shown) which is arranged in the axial direction outside the radial projection of the rotor (4), and claw-pole-like magnetoconductive sheets, preferably 8 or 16 sheets, guided axially in the radial projection of the rotor (4), which leads to an efficient generation of electrical power.

Attached to the housing (106), in particular in the base part (112) is a fluid bypass (119) with a valve (120). The valve (120) comprises a spring (121) and a closing element (122). Initially, the spring (121) exerts a force on the closing element (122), to keep the closing element (122) in a closed state. When the pressure difference over the turbine increases to levels which may damage the generator (101), the force exerted by the fluid on the closing element (122) increases to a level in which this force overcomes the force exerted by the spring (121). In that case, the fluid can flow through the bypass (119) as well as through the inlet nozzle (109), thereby reducing the pressure difference over the turbine exerted by the fluid through the nozzle (109).

The housing (106) comprises two housing sections, a base part (112) and an end part (113), which are or could be water tightly connected through a sealing ring (114). The sealing ring (114) further seals a clearance between the housing (106) and the fluid conduit (123) into which the housing (106) is inserted, like a plug.

The two housing section (112, 113) are for instance coupled via a click-connection. The nozzles (109, 110) are located on opposite sides of the base part (112). The valve (120) is formed with and/or within the base part (112) and thus make integral part of the turbine (101). The fluid conduit (123), partially shown in figures 5 and 6, encloses a channel (118) into which the nozzle (109) and the turbine wheel (102) of the turbine (101) are positioned. The housing (106) of the turbine (101) encloses a guiding channel

(119) for guiding connecting the valve (120) to the fluid conduit (123). the bypass valve

(120) , which therefore makes integral part of the turbine (101). The working principle of the turbine components is similar to the embodiment as shown in figure 4, wherein identical reference signs are used for components with a similar functionality.

Figure 6 shows the hydraulic turbine (101) of figure 5 in exploded view. Not shown in figure 6 are two electrodes (115) which connect to a connector (116), to transfer electricity generated by the generator (101).

Figure 7 shows a bottom view of a cross section of a hydraulic turbine (201) according to a third embodiment of the invention. The turbine (201) is similar to the turbine (101) of the second embodiment shown in figures 4-6, and further shows a bypass channel (224) which is formed by a circumferential groove (224) applied in an outer wall of the housing (206). Fluid can bypass the turbine wheel (202) by flowing through the bypass channel (224).

Figure 8 shows an exploded view of a hydraulic turbine (201) according to a third embodiment of the present invention. The exploded view is similar to the exploded view of the second embodiment as shown in figure 6. However, instead of a bypass valve, the housing (206) is provided with a bypass channel (224), which is always open (independent on fluid pressure). The dimensions of the bypass channel (224) can be matched to the flow of fluid through the flowing conduit (223), such that the amount of fluid flowing through the turbine wheel (202) is tuned to the turbine wheel (202), allowing customized modification of the turbine (201), wherein excess fluid is guided through the bypass channel (224).

It will be clear that the invention is not limited to the illustrative embodiments illustrated and described herein, but that countless variants are possible without departing from the scope of the attached claims which will be obvious to the person skilled in the art.

Claims

1. Insertable turbine for insertion into a fluid conduit, comprising:

at least one turbine wheel,

- at least one generator connected to said turbine wheel, preferably via a common axis, wherein the generator comprises a rotor and a stator with a field winding which are arranged in a housing,

at least one nozzle arranged in said housing for guiding fluid flowing through a fluid conduit towards the turbine wheel, and

- at least two electrical terminals connected to said field winding,

wherein said housing is configured to be partially inserted into a fluid conduit, such that the nozzle and the turbine wheel will be located within said conduit, and such that the electrical terminals will be located outside said conduit.

2. Turbine according to claim 1, wherein each electrical terminal comprises an electrical wire.

3. Turbine according to claim 1 or 2, wherein the field winding is embedded within said housing.

4. Turbine according to claim 3, wherein the field winding is embedded within said housing in a fluid-tight manner.

5. Turbine according to one of the foregoing claims, wherein the housing comprises at least one separation element for separating both the field winding and the electrical terminals from both the rotor and the turbine wheel in a fluid-tight manner.

6. Turbine according to one of the foregoing claims, wherein an insertable part of the housing has a tapered cross-section.

7. Turbine according to one of the foregoing claims, wherein an outer surface of the housing is provided with a sealing means for creating a sealing effect between the turbine and the fluid conduit.

8. Turbine according to one of the foregoing claims, wherein at least one generator is connected to said turbine wheel via a common axis, wherein said axis is supported by the housing.

9. Turbine according to one of the foregoing claims, wherein the housing comprises a laterally protruding shoulder configured to be located outside the fluid conduit.

10. Turbine according to claim 9, wherein the shoulder comprises at least one accommodating space for a mechanical connection element, such as a screw, to connect the turbine to the fluid conduit.

11. Turbine according to one of the foregoing claims, wherein the housing is a modular housing which comprises a base part and a removable end part, said end part being provided with the at least one nozzle.

12. Turbine according to one of the foregoing claims, wherein the nozzle has a curved geometry.

13. Turbine according to one of the foregoing claims, wherein the nozzle is positioned in a plane defined by the turbine wheel.

14. Turbine according to one of the foregoing claims, wherein the turbine also comprises a bypass valve and/or a bypass channel incorporated within said housing allowing fluid to bypass the turbine wheel.

15. Turbine according to one of the foregoing claims, wherein the turbine is configured to be insertable radially into a wall of a fluid conduit.

16. Turbine according to one of the foregoing claims, wherein the turbine is free of typical conduit fittings.

17. Turbine according to one of the foregoing claims, wherein the stator comprises a field winding which is arranged in the axial direction outside the radial projection of the rotor, and claw-pole-like magnetoconductive sheets, preferably 8 or 16 sheets, guided axially in the radial projection of the rotor.

18. Fluid conduit comprising at least one accommodating space for a turbine according to one of the foregoing claims.

19. Assembly of a fluid conduit according to claim 18 and a turbine according to one of claims 1-17, said turbine being partially inserted in the accommodating space of the fluid conduit, wherein the nozzle and the turbine wheel are located within said conduit, and wherein the electrical terminals are located outside said conduit.

20. Assembly according to claim 19, wherein the turbine is fixed to the fluid conduit, preferably by means of mechanical connection means, such as screws.