OIL DRAINAGE

Description

[0001] The invention relates to a transmission according to the preamble of claim 1.

[0002] Wind turbine gearboxes often consist of three gear stages: a driven, input-side planetary stage, an intermediate planetary stage, and a downstream, output-side spur gear stage. Since the driven planetary stage is larger than the intermediate planetary stage, the part of the housing that surrounds the driven planetary stage must be larger than the part of the housing that surrounds the intermediate planetary stage.

[0003] Under normal operating conditions, the oil level in the housing's sump is above the lower edge of the housing section surrounding the intermediate planetary stage. This creates a common oil sump for all three gear stages. However, when the oil is drained, the level drops below the lower edge of the housing section surrounding the intermediate planetary stage. This results in separate oil sumps forming in the housing section surrounding the driven planetary stage and in the housing section surrounding the spur gear stage. To allow these to be drained through a single drain, a drain pipe runs along the base of the gearbox, connecting the housing section surrounding the driven planetary stage and the housing section surrounding the spur gear stage.

[0004] To compensate for manufacturing tolerances and load-induced deformations of the gearbox, the drainage pipe must be flexible. Solutions are known in the prior art that provide a flexible pipe section for this purpose. However, such solutions have a number of disadvantages. For example, flexible pipe sections are susceptible to defects and leaks due to their low mechanical strength. In particular, there is a risk that a flexible pipe section will twist during installation. Since these are rarely used parts that must be specially manufactured, the costs are correspondingly high. Prior art EP 2 001 070 A1 discloses a gearbox with two nested sections of pipe. The nested sections are fixed together with a setscrew.

[0005] The invention is based on the objective of making available a drainage pipe that does not exhibit the disadvantages inherent in solutions known from the prior art. In particular, the drainage pipe should be mechanically robust, cost-effective, and easy to install.

[0006] This problem is solved by a transmission according to claim 1. Preferred embodiments are included in the dependent claims.

[0007] The arrangement comprises a gearbox housing and a pipeline. A pipeline is a conduit designed as a pipe. It is a fluid-conducting connection formed from one or more pipe sections. In this case, the pipeline is designed to conduct fluids, specifically lubricants. The gearbox housing forms an oil sump. The oil sump is a trough-shaped section of the gearbox housing designed to collect lubricant and temporarily store it until it is reintroduced into the lubrication circuit.

[0008] A first section of the pipeline and a second section of the pipeline each lead into the oil sump. Thus, the pipeline forms a lubricant-conducting connection between a first opening into the oil sump and a second opening into the oil sump.

[0009] The first and second pieces each form a pipeline. According to the invention, the first and second pieces are nested inside one another. The first piece was at least partially inserted into the second piece, or the second piece was at least partially inserted into the first piece. As a result, at least a portion of the second piece surrounds at least a portion of the first piece circumferentially with respect to a central axis of the pipeline.

[0010] When nested together, the first and second pieces form the pipeline of the arrangement according to the invention. Accordingly, the first and second pieces are fluid-tightly sealed against each other.

[0011] Because the first and second pieces are nested together, they can move relative to each other. This allows for compensation of dimensional deviations due to manufacturing tolerances and load-induced deformation of the gearbox housing. The plug-in connection between the first and second pieces can be designed geometrically very simply. Therefore, easily manufactured and robust cast parts can be used.

[0012] According to the invention, the plug connection between the first piece and the second piece, consisting of the inner part and the outer part, is axially displaceable along the central axis. This means that the first piece and the second piece are displaceable relative to each other along the central axis.

[0013] The central axis defines the path of the pipeline. It is a curve formed by the geometric centroids of the pipeline's cross-sectional areas. Each geometric centroid of a pipeline's cross-sectional area is part of the central axis. Lubricant flowing through the pipeline flows along the central axis.

[0014] The inventive feature of displacement along the central axis is advantageous because it enables a particularly simple design of the plug connection. A preferred embodiment takes advantage of this, providing at least one seal that fluid-tightly seals the first and second pieces against each other. The seal is fixed immovably in the first piece, for example, in a groove formed by the first piece. The second piece forms a cylindrical section on which the seal rests. Conversely, the seal can be fixed immovably in the second piece and rest on a cylindrical section of the first piece. The seal is annular, meaning it extends around the central axis and is self-contained. It fluid-tightly seals the first and second pieces against each other. Because it merely rests on one of the two pieces, it is displaceable along the central axis.The seal allows unrestricted rotation of the first and second pieces around the central axis. Tilting around axes perpendicular to it is also possible to a limited extent.

[0015] According to the invention, the gearbox housing comprises at least two housing parts. These are designed separately, i.e., not integrally connected. They are joined together, preferably detachably, and thus enclose a cavity within the gearbox housing – the gearbox interior. The gearbox interior contains the gears and bearings. These are lubricated via the aforementioned lubrication circuit.

[0016] One of the housing parts has the first opening of the pipeline into the oil sump, and a second housing part has the second opening. The first section of the pipeline thus opens into the first housing part, and the second section into the second housing part. This implies that each of the two housing parts forms a portion of the lubricant sump. According to the further explanation, the pipeline forms a lubricant-conducting connection between the portion of the oil sump formed by the first housing part and the portion formed by the second housing part.

[0017] The first section of the pipeline and the first housing part can be designed as separate parts or joined together as a single piece. Similarly, the second section of the pipeline and the second housing part can be designed as separate parts or joined together as a single piece.

[0018] Preferably, the gearbox housing is further developed with a third housing part. The third housing part connects the first and second housing parts. This implies that the third housing part is arranged between the first and second housing parts. The third housing part is joined to the first housing part on one side and to the second housing part on the other side. Together, the first, second, and third housing parts encapsulate the interior of the housing.

[0019] The first housing section can contain, for example, an input-side planetary stage, the second housing section a spur gear output stage, and the third housing section an intermediate planetary stage. Due to appropriate dimensioning of the third housing section, it is possible that, at low lubricant levels, the portion of the lubrication sump formed by the first housing section and the portion formed by the second housing section are no longer connected via the third housing section. In this case, the pipeline acts as a bypass, "short-circuiting" the first and second housing sections and connecting them via the third housing section.

[0020] Preferred embodiments of the invention are illustrated in the figures. Matching reference numerals denote identical or functionally equivalent features. Specifically, the figures show: Fig. 1 shows an external view of a gearbox housing; and Fig. 2 shows a detailed longitudinal section view.

[0021] A gearbox 101 according to Fig. 1 The assembly comprises a first housing part 103, a second housing part 105, and a third housing part 107. The first housing part 103 and the third housing part 107 each enclose a planetary gear stage. A spur gear stage of the transmission 101 is located in the second housing part 105.

[0022] The second housing part 105 has a drain valve 109 for gear oil. The drain valve 109 is located at the lowest point of the gearbox 101. It serves to drain gear oil from the gearbox housing 101.

[0023] The third housing part 107 is arranged between the first housing part 103 and the second housing part 105. It is smaller than the first housing part 103 and the second housing part 105. In particular, the first housing part 103 and the second housing part 105 project vertically downwards beyond the third housing part 107. Thus, a lower end of the first housing part 103 and a lower end of the second housing part 105 are located vertically below a lower end of the second housing part 105.

[0024] If the level of an oil sump formed by the gearbox housing 101 falls below the lower end of the second housing part 107, there is no longer a lubricant-conducting connection between a part of the oil sump formed by the first housing part 103 and a part of the oil sump formed by the second housing part 105 via the second housing part 107. Therefore, a pipe 111 is provided which connects these parts of the oil sump in a lubricant-conducting manner.

[0025] The pipe 111 is located at the base of the gearbox 101 or the gearbox housing 103, 105, 107. It extends between the first housing part 103 and the second housing part 105, thus bridging the third housing part 107. Oil that collects in the first housing part 103 when the oil is drained passes through the pipe 111 into the second housing part 105 and can be removed from the gearbox 101 via the drain valve 109.

[0026] The in Fig. 1The illustrated pipeline 111 has a flexible section 113 known from the prior art. An alternative according to the invention is in Fig. 2 depicted.

[0027] Pipeline 111 will be constructed according to Fig. 2 formed by a first section 201 and a second section 203. The first section 201 is bolted to the first housing part 103 via a first flange connection 205. Similarly, the second pipe section 203 is bolted to the second housing part 105 via a second flange connection 207.

[0028] The first section 201 has two grooves 209, each containing a seal 211. The grooves 209 and the seals 211 extend rotationally symmetrically around the central axis. Accordingly, the first section 201 is rotationally symmetrical in this area.

[0029] The rotationally symmetrical section of the first segment 201 is inserted into a cylindrical section 213 of the second pipe segment 203 via the grooves 209 and the seals 211. The cylindrical section 213 has the shape of the lateral surface of a right circular cylinder. The seals 211 form an oil-tight seal against the cylindrical section 213.

[0030] Within the cylindrical area 213, the seals 211 are displaceable along the central axis of the pipe 111. Accordingly, the first pipe section 201 and the second pipe section 203 can be displaced relative to each other. The sealing effect of the seals 211 is maintained. This allows dimensional deviations 101 and load-induced deformations of the gearbox housing to be compensated for. Reference sign

[0031] 101 Gearbox housing 103 First housing part 105 Second housing part 107 Third housing part 109 Drain valve 111 Pipeline 113 Flexible section 201 First section 203 Second section 205 First flange connection 207 Second flange connection 209 Groove 211 Gasket 213 Cylindrical section

Claims

1. Transmission having a transmission housing (101) and having a pipeline (111); wherein the transmission housing (101) forms a lubricant sump; wherein a first piece (201) and a second piece (203) of the pipeline (111) each open out into the lubricant sump; wherein the first piece (201) and the second piece (203) are plugged one into the other; and wherein the first piece (201) opens out into a first of the housing parts (103) and the second piece (203) opens out into a second of the housing parts (105); characterized in that the first piece (201) and the second piece (203) are displaceable relative to one another along a central axis.

2. Transmission according to the preceding claim; characterized by at least one seal (211) which seals off the first piece (201) and the second piece (203) in a fluid-tight manner with respect to one another; wherein the seal (211) is fixed in a non-displaceable manner in the first piece (201); wherein the second piece (203) forms a cylindrical region (213); and wherein the seal (211) bears against the cylindrical region (213).

3. Transmission according to either of the preceding claims; characterized by a third housing part (107) which connects the at least two housing parts (101, 103) to one another.