The present invention relates to a gear lubrication system especially designed for wind turbines, which prevents wear being produced as a result of friction between the teeth of two meshed gear wheels subjected to great stress and which furthermore optimizes the manufacturing, assembly and subsequent maintenance thereof.

Background of the invention

A large variety of gear lubrication systems are currently known wherein a first cogwheel engages with a second cogwheel in order to transmit movement. Specifically, within the field of wind turbine manufacturing, these systems are of extreme importance, since they facilitate the lubrication of the gears used in systems for regulating the wind turbine's power.

These gears are used in systems that direct the turbine towards the wind, known as

"yaw" systems, for example, as well as in systems that alter the angle of the turbine blades, known as "pitch" systems. These gears mainly comprise a transmission pinion, which engages to a ring gear, in order to transmit the power that said pinion receives from a motor on said ring.

In dynamic conditions or during operation, the gears in yaw systems are subjected to alternating tensile and compressive stress. Similarly, the gears in pitch systems are also subjected to such alternating stress, however, in this case, as a result of the different wind speeds and changes in wind direction. Said alternating stress gives rise to slight movement within the gear, which during long operating times in the same position, expels the lubricant, thus giving rise to friction between the surfaces of the gear wheels that come into contact with one another, thereby wearing down the teeth.

Meanwhile, the current trend in this sector is to manufacture blades with a large diameter in order to capture more kinetic energy from the wind and thereby increase the electrical power generated by the wind turbine. This increase in size has led to increased static loads on the main components of the wind turbine, thus amplifying the problems set out above.

As such, some lubrication systems for this type of gears are known which comprise injector devices designed to directly inject the lubricant into the proximity space delimited by the surfaces that come into contact between cogwheels, i.e. the space delimited by one bottomland surface (dedendum) and one top-land surface (addendum), thereby guaranteeing that there is lubricant at all times.

One of these systems can be observed in document US7699584. Said document specifically reveals a lubrication device comprising a lubrication passage formed in the transmission pinion or ring gear. Said passage is arranged cross-wise or perpendicularly to the bottom-land and top-land surfaces, or likewise arranged radially relative to the pinion or ring. This configuration means that the lubrication passage is fairly inaccessible, thus making it difficult to connect to the remaining elements in the system, such as the distribution circuit or lubricant supply pump, it being necessary to incorporate these elements inside the pinion or ring in some cases. All of this complicates the manufacturing, assembly and maintenance processes for this lubrication system considerably.

These problems are partly resolved in the lubrication system disclosed in document WO2014/009588. Specifically, this document discloses a piece that is substantially flat in design, which adapts to the bottom-land surface between two contiguous teeth, inside the proximity space. The lubricant is injected through a system of channels with a side opening, these channels being designed using micro fluid technology inside said piece. This efficient system makes the manufacturing process much easier to carry out, given that said pieces can easily adapt to the bottom-land surface. It also improves the assembly process, given that the side openings improve accessibility. Nevertheless, some problems related to the subsequent maintenance of the system and space available between the meshed teeth persist. As far as maintenance is concerned, it is not always easy to replace or change these pieces, given that they are located inside the narrow proximity space between the meshed teeth. In terms of the space available, the size of the piece must be measured with sufficient precision, so that it can be housed in extremely small spaces, leaving a certain amount of a gap so that potential dilations in the cogwheels can be absorbed.

The present invention resolves the problems set out above, by means of a gear lubrication system comprising an efficient injector device, which is small in size, easy to assemble and incredibly easy to access once assembled, furthermore being designed to work alongside a lubrication passage formed in one of the gear wheels. Said lubrication passage is arranged longitudinally relative to the bottom-land surface or top-land surface, i.e. arranged such that it is parallel to or slopes in relation to the same, it being possible to machine the same on said wheel very easily. The system object of the present invention is also very versatile, since it may be assembled to the bottom-land surface or top-land surface of any of the gear wheels.

Description of the invention

The gear lubrication system object of the present invention comprises:

• a first wheel with a number of first teeth;

· a second wheel with a number of second teeth, designed to engage with the first teeth, defining at least one proximity space delimited by a bottom-land surface between two first contiguous teeth and a top-land surface of a second tooth, which engages with the same; and

• an injector device, designed to receive the lubricant from a distribution circuit, connected to a supply pump, then to inject said lubricant into the proximity space.

Said system is characterized in that the injector device comprises:

• a connection piece that may be connected to the distribution circuit, designed to adapt to a side surface of one of the gears;

• a lubrication passage formed in the gear upon which the connection piece is adapted, arranged longitudinally relative to the bottom-land surface or top-land surface and designed to receive the lubricant from the connection piece; and

• one or more injection holes linked to the lubrication passage and directed towards the proximity space.

The term bottom-land surface refers to the dedendum or root between two first contiguous teeth and may also be extended, depending on the area in which it comes into contact with the second tooth, to part or all of the opposing flanks of said first teeth. Likewise, the term top-land surface refers to the addendum or head of the second tooth and may also be extended depending on the area in which it comes into contact with the first teeth, to part or all of the opposing faces of said second tooth. The proximity space is delimited longitudinally by the side surfaces of the gears, which are perpendicular, or substantially perpendicular, to the rotation axes of the same.

As shall be seen later on, the lubrication passage may be arranged longitudinally such that it is parallel to or sloped in relation to the corresponding bottom-land surface or top-land surface. In any case, this arrangement of the lubrication passage should be seen to follow a trajectory parallel, or substantially parallel, to the rotation axis of the corresponding gear.

In order to facilitate the assembly of and access to the injector device, the connection piece preferably comprises fastening means designed to fasten said piece to the side surface of the gear, either perpendicularly or substantially perpendicularly to the bottom-land surface or top-land surface. In turn, the connection piece comprises:

· an inlet connector, designed to be connected to the distribution circuit, which has a lubricant inlet passage; and

• a fastening block, which may be coupled to the inlet connector and which in turn includes a linking passage, which links to the inlet passage, in addition to an outlet hole, which is linked to the lubrication passage.

The fastening block preferably has a support base with fastening holes, which are opposite a number of reception holes made in the side surface of the gear, in order to work together with screws. In order to prevent potential lubricant leaks at the communication point between the outlet hole and the lubricant passage, the fastening block comprises a groove around the hole, designed to receive a seal-tight join. In order to make it possible to connect the injector device to the distribution circuit, the fastening block comprises a coupling module to quickly attach one connection end of the inlet connector.

As already mentioned, the gear lubrication system object of the present invention is incredibly versatile, since it may be assembled in many different ways.

According to a first preferred embodiment, the lubrication passage is formed by a channel closed at the perimeter lengthwise, which is either parallel to or slopes in relation to the bottom-land surface or top-land surface and moves relative to said surface. It is possible to machine said closed channel simply by drilling the gear in question. In turn, the closed channel comprises an inlet hole, located on the side surface of the corresponding gear and designed to be connected to the connection piece and an injection channel, wherein the injection hole is located.

The first embodiment enables many different variations, it being possible to assemble the injector device on any gear and to assemble the same to a bottom-land or top-land surface of said gear.

According to a second preferred embodiment, the lubrication passage is formed by a channel open at the perimeter lengthwise, which is parallel to the bottom-land surface or top- land surface and which is machined on said surface. Likewise, said open channel may easily be machined by carrying out a drilling or milling process prior to cutting. In turn, the connection piece comprises a lubrication body designed to adjust to the bottom-land or top-land surface, located inside the proximity space, which in turn is equipped with:

• a rear face directed towards the open channel; and

• a front face directed towards the proximity space in which one or more injection holes are arranged.

The lubrication body preferably comprises a closure channel arranged on the rear face, opposite the open channel and configured to close said open channel at the perimeter. In turn, the lubrication body comprises an injection chamber, which links the open channel to one or more injection holes.

In order to close the open channel lengthwise, the lubrication body comprises an obstacle in the lubricant passage, which is aligned with the closure channel at an internal end of the lubrication body and designed to slide along the length of the open channel, where the cross-section of said obstacle coincides with that which forms the open channel and the closure channel, which are in turn connected.

In order to facilitate its insertion and suitable adjustment on the bottom-land or top-land surface of the corresponding gear, the lubrication body comprises a fastening and sealing element parallel to the closure channel, configured to slide along the length of a machined fastening groove on the bottom-land or top-land surface, which remains fixed to the same.

The second embodiment enables many different variations, it being possible to assemble the injector device on any gear and to assemble the same to a bottom-land or top- land surface of said gear.

Brief description of the drawings

Below is a very brief description of a series of drawings, which facilitate a better understanding of the invention and are linked expressly to various preferred embodiment thereof, which constitute non-limiting examples of the same.

Figure 1 is a perspective view of a gear assembly.

Figure 2 is a plan view of the gear shown in Figure 1.

Figure 3 is a detailed view of "Z" shown in Figure 2.

Figure 4 is a perspective view of the gear lubrication system object of the present invention, in accordance with a first embodiment thereof.

Figure 5 is a perspective view of the injector device shown in Figure 4.

Figure 6A is a longitudinal cross section of an injector device, in accordance with a first embodiment.

Figure 6B is a detailed view of "W" shown in Figure 6A.

Figure 7 is a detailed plan view of the area in which the connection piece adapts, in accordance with a first embodiment.

Figure 8 is a first perspective view of the fastening block, in accordance with a first embodiment.

Figure 9 is a second perspective view of the fastening block, in accordance with a first embodiment.

Figure 10 is a perspective view of the gear lubrication system object of the present invention, in accordance with a second embodiment thereof.

Figure 1 1 is a longitudinal cross section of an injector device, in accordance with a second embodiment.

Figure 12 is a detailed plan view of the area in which the connection piece adapts, in accordance with a second embodiment.

Figure 13 is a first perspective view of the connection piece, in accordance with a second embodiment.

Figure 14 is a second perspective view of the connection piece, in accordance with a second embodiment.

Figure 15 is a third perspective view of the connection piece, in accordance with a second embodiment.

Figure 16 is a perspective view of the injector device, in accordance with a variant of the second embodiment.

Figure 17 is a perspective view of the open channel, in accordance with a variant of the second embodiment.

Figure 18 is a detailed plan view of the open channel, in accordance with a variant of the second embodiment.

Figure 19 is a first perspective view of the connection piece, in accordance with a variant of the second embodiment.

Figure 20 is a second perspective view of the connection piece, in accordance with a variant of the second embodiment.

Detailed description of the invention

Figures 1 and 2 are a respective perspective and plan view of a gear assembly. As can be seen, said gear assembly comprises a first wheel (2) with a number of first teeth (21 ) and a second wheel (3) with a number of second teeth (31 ) designed to engage with the first teeth (21 ). According to the present example, the first wheel (2) corresponds to a ring gear, whilst the second wheel corresponds to a transmission pinion.

Figure 3 shows how the first teeth (21 ) engage with the second teeth (31 ) in more detail. As can be seen, they define a proximity space (4) delimited by a bottom-land surface (22) between two first contiguous teeth (21 ) and a top-land surface (32) of a second tooth (31 ), which engages with the same. Figure 4 is a perspective view of the gear lubrication system (1 ) object of the present invention, in accordance with a first embodiment thereof. As can be seen, the system (1 ) comprises an injector device (10) configured to receive the lubricant from a distribution circuit (6) connected to a supply pump (5) and to inject said lubricant into the proximity space (4).

Figures 5, 6A and 6B are respective perspective, longitudinal cross section and detailed views of the injection device (10). For the purposes of improved clarity, the cross section shown in Figure 6A was taken of the injector device (10) directed in the opposite direction to that shown in Figures 4 and 5. As can be seen, the injector device (10) comprises:

• a connection piece (1 1 ) that may be connected to the distribution circuit (6), designed to adapt to a side surface (23) of the first gear (2);

• a lubrication passage (12) formed in the first gear (2), arranged longitudinally relative to the bottom-land surface (22) and designed to receive the lubricant from the connection piece (1 1 ); and

• one or more injection holes (13) linked to the lubrication passage (12) and directed towards the proximity space (4).

According to the present example, the longitudinal arrangement of the lubrication passage (12) is parallel to the bottom-land surface (22). In other words, it follows a trajectory parallel to the rotation axis of the first wheel (2). In other embodiments, said lubrication passage (12) may be slightly sloped; however, it would still be arranged longitudinally.

In order to facilitate the assembly of and access to the injector device (10), the connection piece (1 1 ) comprises fastening means (100) designed to fasten said piece (1 1 ) to the side surface (23) of the first gear (2), either perpendicularly or substantially perpendicularly to the bottom-land surface (22). In turn, the connection piece (1 1 ) comprises:

• an inlet connector (1 1 1 ), designed to be connected to the distribution circuit (6), which has a lubricant inlet passage (1 12); and

• a fastening block (1 14), which may be coupled to the inlet connector (1 1 1 ) and which in turn includes a linking passage (1 15), which links to the inlet passage (1 12), in addition to an outlet hole (1 16), which is linked to the lubrication passage (12). Figure 7 is a detailed plan view of the area in which the connection piece (1 1 ) adapts. As can be seen, the lubrication passage (12) is formed by a channel closed (121A) longitudinally along its perimeter and parallel to the bottom-land surface (22), as can clearly be seen in Figure 6A, and moved slightly relative to said surface (22). In turn, the closed channel (121A) comprises an inlet hole (122A), located on the side surface (23) of the first corresponding gear (2) and designed to be connected to the connection piece (1 1 ) and an injection channel (123A), wherein the injection hole (13) is located, Figure 6B.

Figures 8 and 9 are respectively a first and a second perspective view of the fastening block, which facilitates the adaptation of the connection piece (1 1 ) to the side surface (23). As can be observed, said fastening block (1 14) has a support base (1 141 ) with a pair of fastening holes (1 142), which are opposite a pair of reception holes (24) made in the side surface (23) of the first gear (2), in order to work together with screws (101 ), Figures 5 and 6. In order to prevent potential lubricant leaks at the link point between the hole (1 16) and lubricant passage, the fastening block (1 14) comprises a groove (1 143) around the hole (1 16), designed to receive a seal-tight join (1 17). In order to make it possible to connect the injector device (10) to the distribution circuit (6), the fastening block (1 14) comprises a coupling module (1 144) to quickly attach one connection end (1 13) of the inlet connector (1 1 1 ).

Figures 10, 1 1 and 12 are distinct views of the gear lubrication system (1 ) object of the present invention, in accordance with a second embodiment. As can be seen, the lubrication passage (12) is formed by a channel open (121 B) longitudinally along its perimeter and parallel to the bottom-land surface (22), the same being machined on said surface (22). In turn, the connection piece (1 1 ) comprises a lubrication body (122B) designed to adjust to the bottomland surface (22), located inside the proximity space (4).

Figures 13, 14 and 15 constitute a respective first, second and third perspective view of the connection piece (1 1 ), in accordance with a second embodiment. For the purposes of improved clarity, the inlet connector (1 1 1 ) is not shown in the figures. As can be seen, the lubrication body (122B) extends from the fastening block (1 14) and in turn, has:

• a rear face (123B) directed towards the open channel (121 B); and

• a front face (124B) directed towards the proximity space (4) in which one or more injection holes (13) are arranged. The lubrication body (122B) comprises a closure channel (125B) arranged on the rear face (123B), opposite the open channel (121 B) and configured to close said open channel (121 B) at the perimeter. In turn, the lubrication body (122B) comprises an injection chamber (126B), which links the open channel (121 B) to a pair of injection holes (13).

In order to close the open channel (121 B) lengthwise, the lubrication body (122B) comprises an obstacle (127B) in the lubricant passage, which is aligned with the closure channel (125B) at an internal end (128B) of the lubrication body (122B) and designed to slide along the length of the open channel (121 B), where the cross section (S _B ) of said obstacle (127B) coincides with that formed by the open channel (121 B) and the closure channel (125B) once connected.

In order to facilitate its introduction and suitable adjustment on the bottom-land surface (22) of the first gear (2), the lubrication body (122B) comprises a fastening and sealing element (129B) parallel to the closure channel (125B), configured to slide along the length of a fastening groove (25) machined on the bottom-land surface (22), which remains fixed to the same and guarantees sealing.

Figure 16 is a perspective view of the injector device (10), in accordance with a variant of the second embodiment. As can be observed, in this case, the connection piece (1 1 ) is found on a top-land surface.

Figures 17 and 18 are respective perspective and detailed plan views of the open channel (121 B) according to said variant embodiment.

Figures 19 and 20 constitute a respective first and second perspective view of the connection piece (1 1 ), in accordance with said variant embodiment. For the purposes of improved clarity, the inlet connector (1 1 1 ) is not shown in the figures.