Hydraulic control device

Abstract

The hydraulic control device includes a body mounted for rotation on a shaft having a hydraulic channel for supplying a hydraulic medium, the hydraulic channel leading into a working chamber bounded by the body and an annular piston mounted on the body for axial movement. The control device includes an annular seal element received within the body and fixed on the shaft, and a leakage return path extending from the outside of the shaft to the working chamber. The leakage return path extends through the seal element. The shaft has at least two axial portions with different outer diameters. The seal element is fixed on the axial portion with the smaller outer diameter, and a seal lip of the seal element abuts the outside of the shaft. The seal element is axially supported on a support ring received within the body.

Description

[Technical Field]

[0001] The present invention relates to a hydraulic position control device according to the preamble of claim 1 .

[0002] EP2923908B1 discloses a hydraulic control device having a pot-shaped body rotatably mounted on a shaft with a hydraulic channel for introducing hydraulic fluid. The hydraulic channel extends to a working chamber bounded on one side by the body and on the other side by an annular piston axially movably disposed in the body. An annular seal device with two annular seals is disposed on the shaft and bounds a leakage path extending from the outside of the shaft to the working chamber.

[0003] An object of the present invention is to provide a hydraulic control device with high safety against leakage.

[0004] According to the invention, this object is achieved by the features of claim 1. The dependent claims define suitable further embodiments.

[0005] In the following, the term "axial" means in the direction of or parallel to the longitudinal shaft axis that forms the axis of rotation in addition to the longitudinal axis of the hydraulic position control device, and the term "radial" means perpendicular to the longitudinal shaft axis.

[0006] The hydraulic control device according to the present invention may be used, for example, to adjust the vanes of a blower or fan wheel in which the vanes are supported so as to be pivotable about a longitudinal vane axis. The hydraulic control device comprises a body rotatably supported on a shaft provided with a hydraulic channel for the introduction of hydraulic fluid. The hydraulic channel extends to a variable-volume working chamber bounded by the body and a pot-shaped annular piston axially adjustable supported by the body. The position of the annular piston in the body is adjustable by supplying hydraulic fluid to the working chamber. The movement of the annular piston is transmitted to a component, such as a fan blade of a fan wheel, that is adjustable from a first state to a second state to move the blade from a first blade position to a second blade position.

[0007] In a preferred embodiment, a force is applied to the annular piston in an axial direction towards the body, particularly via one or more spring elements. When hydraulic fluid is supplied to the working chamber, the volume of the working chamber increases and the annular piston moves axially against the force of the spring elements.

[0008] Additionally, the control device includes an annular seal element housed within a body supported on the shaft. The control device further includes a leakage return passage extending from the outside of the shaft to the working chamber, whereby the leakage return passage extends at least partially through the seal element. Via the leakage return passage, hydraulic oil leaking from the working chamber upwardly outside the shaft between the shaft and the seal element can be returned to the working chamber.

[0009] The shaft has at least two axial portions with different outer diameters. The seal element is fixed on the axial portion with the smaller diameter, and the seal lip of the seal element abuts the outside of the shaft. The seal element is axially supported by a support ring housed within the body. The seal lip of the seal ring may be supported by the support ring.

[0010] This device has several advantages. The sealing element is arranged in the body and rotates with the body relative to the shaft, thereby reducing the shaft diameter, which reduces the circumferential speed of the sealing element in the contact area with the shaft. If the shaft diameter is reduced by, for example, 20% in this axial section, the circumferential speed also decreases by this amount compared to the circumferential speed in the axial section of a shaft with a larger diameter. As a result, pressure and wear on the sealing material are reduced, and the operating period of the sealing element and therefore of the position control device is also increased.

[0011] Further advantageously, the seal element is axially supported by a support ring. The axial force acting on the seal element is adjusted by the support ring. The seal element is axially engaged between a portion of the body and the support ring, and is thereby axially fixed. The connections between the leakage return passages at the transitions to and from the seal element are maintained with high dimensional accuracy over long operating periods.

[0012] The support ring is advantageously arranged axially at the level of the transition shoulder between shaft sections of different outer diameters. Advantageously, the support ring has an inner diameter greater than the outer diameter of the shaft so as to provide a radial space around the shaft. In this way, it is ensured that there is no frictional contact between the support ring and the outer surface of the shaft during rotation of the body and the support ring.

[0013] According to another advantageous embodiment, the sealing element, with its front side facing the working chamber, abuts axially against an elastic tension element housed in the body part.

[0014] The support rings and the resilient tension elements can each extend over only a portion of the radial width of the respective front side of the sealing element, thereby enabling the front side of the sealing element to form a contoured surface with ledges that are only partially supported by the resilient tension elements or support rings, respectively.

[0015] According to another advantageous embodiment, the body includes a body base and a sealing flange disposed immediately adjacent to the hydraulic fluid receiving area. In this case, the body is made of two parts. This has the advantage that the sealing element can be slid onto the shaft and properly positioned within the sealing flange before the structure is fully assembled. The sealing flange can then be secured to the body base so that the sealing element can be secured in its final desired position between the body base and the sealing flange.

[0016] The body comprises a bearing device on which the shaft is rotatably supported. When sliding the bearing device onto the shaft, it may be advantageous to first place a hose-like support device on the shaft in the region of the reduced diameter axial section and then slide the sealing element onto the shaft, in order to avoid damage to the sealing seat during the assembly process. When the bearing device is in the desired position on the shaft, the hose-like support device can be removed.

[0017] The sealing flange may be provided with a thread that can be screwed into an opposing thread provided on the body base. This arrangement has the advantage that no additional mounting elements are required for connecting the body base and the sealing flange. Rather, it is sufficient to screw the sealing flange together with the body base. The thread is provided, for example, on a cylindrical receiving protrusion on the sealing flange in the form of an external thread that is threaded into a corresponding internal thread provided in the opening in the receiving protrusion.

[0018] According to another advantageous embodiment, the sealing flange is provided with a leakage passage that is part of the leakage return passage and that communicates with a seal leakage return channel that is part of the leakage return passage and that extends through the sealing element. In this way, leakage liquid is transmitted from the outside of the shaft to the working chamber via the seal leakage channel in the sealing element and the leakage channel in the sealing flange. The seal leakage channel in the sealing element preferably extends radially relative to the longitudinal axis of the shaft, and the leakage channel in the sealing flange extends at least partly axially.

[0019] According to a further advantageous embodiment, the front end of the shaft terminates in a sealing flange provided with a hydraulic hole aligned with the hydraulic channel in the shaft, where it is particularly advantageous for the internal diameter of the hydraulic hole in the sealing flange to be the same size as the internal diameter of the hydraulic channel in the shaft from the shaft to the hydraulic hole in the sealing flange, thereby ensuring a continuous flow of hydraulic oil supply.

[0020] In yet a further advantageous embodiment, the outer surface of the shaft is coated with a friction-reducing layer, which reduces friction between the shaft and a sealing element disposed on the shaft when rotating relative to the shaft.

[0021] The invention also relates to a fan wheel having fan vanes pivotally supported about a vane axis, the fan wheel being provided with a control device as described above for pivoting the fan vanes, the axial control movement of the annular piston being translated into pivotal movement of the fan vanes, and the control device may form the hub of the fan wheel.

[0022] Further advantages and advantageous embodiments are evident from the dependent claims, the description of the drawings and the drawings. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a longitudinal cross-sectional view of a hydraulic control device having a body rotatably supported on a shaft with a hydraulic channel for the introduction of hydraulic fluid, an annular piston axially adjustably supported on the body, and an annular sealing element arranged on the shaft. [Figure 2] Enlarged portion of the area with the sealing element.

[0024] In the figures, identical parts are designated by the same reference numerals.

[0025] The illustrated control device (1) is hydraulically operable and may be used, for example, to adjust a blower or fan vanes supported in a blower or fan wheel so that they are pivotable about the longitudinal axis of the vanes. The control device (1) comprises a body (2), a shaft (3), and an annular piston (4), with the shaft (3) being stationary or fixed, and the body (2) and annular piston (4) supported on the shaft (3) for free rotation about the shaft axis (5). This allows the control device (1) to be integrated into the hub of the fan wheel, and hydraulic fluid to be supplied via the stationary shaft (3) to drive the control device (1) and the adjustable air vanes of the blower wheel. The body (2) comprises a bearing arrangement (6) that receives the shaft (3) for free rotation about the longitudinal shaft axis (5).

[0026] The annular piston (4) is supported on the main body (2) so as to be axially movable but not rotatable, and is biased toward the main body (2) by a spring element. A variable-volume working chamber (7) for receiving hydraulic oil is located between the front side of the main body (2) and the front side of the annular piston (4) facing the main body, and hydraulic oil is supplied to the working chamber via the shaft (3). The shaft (3) has an axially extending hydraulic channel (8), through which hydraulic oil is conducted from the outside to the working chamber (7). When hydraulic oil enters the working chamber (7), the annular piston (4) is biased axially away from the main body against the force of the spring element, thereby increasing the volume of the working chamber (7). This movement of the annular piston (4) is used as an adjustment movement, for example, to adjust the position of vane blades of a fan wheel.

[0027] The body (2) comprises two parts, a body base (9) and a sealing flange (10), the front side of which delimits the working chamber (7) and faces the front side of the adjacent annular piston (4), which forms a further delimiting surface for the working chamber (7). The sealing flange (10) is connected to the body base (9) by a threaded connection (11). For this purpose, the sealing flange (10) is formed with an externally threaded portion on its annular axial extension (12), which is internally threaded and threaded onto the body base (9).

[0028] The seal flange (10) has an axial opening for receiving the shaft (3). The front end of the shaft (3) terminates in the seal flange (10) with a hydraulic bore (22) that extends coaxially with the hydraulic channel (8) in the shaft (3). The inner diameter of the hydraulic bore (22) in the seal flange (10) is the same as the inner diameter of the hydraulic channel (8) in the shaft (3), thereby providing a continuous flow path with a constant diameter from the shaft (3) to the hydraulic bore (22) in the seal flange (10), ensuring a continuous flow of hydraulic fluid. The receiving passage for receiving the shaft (3) has an annular dirt collection groove (24) at the transition to the hydraulic bore (22), which has a smaller diameter than the receiving passage. The dirt collection groove (24) has a larger diameter than the receiving passage.

[0029] The axial receiving extension (12) has a recess in which an annular seal element (13) is axially supported, with the shaft (3) inserted. The outer surface of the shaft (3) is coated with a friction-reducing coating, which allows the seal element (13) to rotate around the shaft (3) with minimal friction. The seal element (13) is located in a first leakage path (14) extending from the outside of the shaft (3) to the working chamber (7). Any hydraulic fluid leaking axially from the working chamber (7) along the outer wall of the shaft returns to the working chamber (7) via this leakage path. A second leakage path (15) extends from the working chamber (7) between the inner wall of the annular protrusion (16) of the annular piston (4) and the adjacent walls of the body base (9) and seal flange (10). The second leakage path is provided with a seal device (17) having two individual annular seals (17a) and (17b) located in the body base (9) and seal flange (10). The sealing device (17) has a hydraulic pumping effect to return leakage back to the working chamber (7).

[0030] The shaft (3) has multiple axial sections with different outer diameters. The axial section (3a) of the shaft (3) with the larger outer diameter extends into the body base (9), while the adjacent axial section (3b) with the smaller outer diameter extends into the sealing flange (10). An annular transition shoulder (18) is formed on the shaft (3) between the axial sections (3a) and (3b).

[0031] The sealing element (13) is fixed on the axial portion (3b) having a smaller diameter, and a sealing lip (13a) of the sealing element (13) abuts the outside of the shaft and delimits a first leakage path (14). The sealing element (13) with the sealing lip (13a) is axially supported on a support ring (19) that is supported by being housed in the body base (9) and opposite the working chamber (7). The inner diameter of the support ring (19) is larger than the outer diameter of the shaft (3) and is arranged at a radial distance from the outer wall of the shaft, so that friction between the support ring (19) and the shaft surface is avoided.

[0032] A sealing lip (13a) of the sealing element (13) defines a low-pressure side leakage path (14). A second sealing lip (13b) of the sealing element (13) axially spaced from the first sealing lip (13a) and positioned near the working chamber (7) defines a high-pressure side leakage path (14).

[0033] On its front side facing the working chamber (7), the sealing element (13) abuts against an annular spring element (23) housed in the sealing flange (10).

[0034] The leakage return path for returning leakage fluid from outside the shaft (3) to the working chamber (7) comprises a radial seal leakage passage (20) in the seal element (13) and a leakage passage (21) adjacent to the seal leakage passage (20) in the seal flange (10). The leakage channel (21) comprises an annular receiving chamber (21a) extending radially outward from the seal leakage passage (20) in the seal element (13) and a plurality of circumferentially distributed axial holes (21b) extending from the annular receiving chamber (21a) to the region between the body base (9) and the seal flange (10). The two annular seals of the sealing device (17) are axially arranged above and below the region between the body base (9) and the seal flange (10).

[0035] The sealing lip (13a) of the sealing element (13) prevents leakage fluid exiting the working chamber (7) along the shaft from flowing past the sealing element (13). The sealing lip (13a) directs leakage fluid radially outward toward a radial sealing leakage path (20) in the sealing element (13) that is supported by the rotation of the body (2) and the annular piston (4).

[0036] The leakage fluid travels further radially outward from the seal leakage passage (20) into the surrounding annular receiving chamber (21 a), and then axially downward through the holes (21 b) towards the region between the body base (9) and the seal flange (10). From there, the leakage fluid passes through the sealing device (17) and returns to the working chamber (7).

Claims

1. A hydraulic position control device, a body (2) rotatably supported on a shaft (3) provided with a hydraulic channel (8) for the introduction of hydraulic fluid into a working chamber (7), said working chamber (7) being bounded by said body (2) and an annular piston (4) supported on said body (2) in an axially adjustable manner; an annular sealing element (13) disposed on the shaft (3) within the body (2); a leakage return path extending from an outer region of the shaft to the working chamber (7); the leakage return path extends through the annular sealing element (13), the shaft (3) has at least two axial portions (3a, 3b) with different outer diameters, the annular sealing element (13) being fixed on the axial portion (3b) with the smaller diameter, The sealing element (13) is axially supported by a support ring (19) provided in the body (2) and has a sealing lip (13a) that abuts against the outside of the shaft (3). A hydraulic position control device characterized by:

2. 2. The hydraulic position control device according to claim 1, wherein the body (2) comprises a body base (9) and a sealing flange (10) arranged adjacent to the working chamber (7).

3. 3. The hydraulic position control device according to claim 2, wherein the sealing flange (10) is provided with a threaded portion (11) that is threaded on the opposite thread provided on the body base (9).

4. 4. The hydraulic position control device according to claim 2, wherein the sealing flange (10) is provided with a leakage passage (21) that is part of the leakage return path.

5. 5. The hydraulic position control device according to claim 2, wherein the shaft (3) has a front portion (3b) terminating in the sealing flange (10) provided with a hydraulic hole (22) aligned with the hydraulic channel (8).

6. 6. The hydraulic position control device according to claim 5, characterized in that the inner diameter of the hydraulic hole (22) in the sealing flange (10) is the same as the inner diameter of the hydraulic channel (8) in the shaft (3).

7. 7. The hydraulic position control device according to claim 1, wherein the inner diameter of the support ring (19) is larger than the outer diameter of the shaft (3), and the support ring is arranged on the shaft (3) at a radial distance from the outside of the shaft (3).

8. The hydraulic position control device according to any one of claims 1 to 7, characterized in that the sealing element (13) with its front side facing the working chamber (7) abuts against a spring element (23) housed in the sealing flange (10).

9. The hydraulic position control device according to any one of claims 1 to 8, characterized in that the seal element (13) is provided with a seal leakage passage (20) that extends radially relative to the shaft axis (5) and is part of the leakage return path.

10. Hydraulic position control device according to any one of claims 1 to 9, characterized in that the surface of the shaft (3) has a friction-reducing coating.

11. A fan wheel having fan blades pivotally supported about a longitudinal blade axis, comprising a fan blade position control device (1) according to any one of claims 1 to 10 for pivoting the fan blades.

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