Variable flow hydraulic circuit for a wind turbine

Abstract

A hydraulic circuit for a wind turbine is provided. The hydraulic circuit includes: a fixed displacement pump including a suction input and a delivery output, a pump motor for driving the fixed displacement pump, a pressure line hydraulically connected to the delivery output of the fixed displacement pump for delivering an output flow and/or an output pressure generated by the fixed displacement pump towards at least a consumer circuit, a bypass valve including a valve input hydraulically connected to the delivery output of the fixed displacement pump, wherein the bypass valve includes a variable opening for controlling the output flow or the output pressure delivered by the fixed displacement pump towards the consumer circuit(s).

Claims

1. A hydraulic circuit for a wind turbine, the hydraulic circuit comprising: a fixed displacement pump including a suction input and a delivery output; a pump motor for driving the fixed displacement pump; a pressure line hydraulically connected to the delivery output of the fixed displacement pump for delivering an output flow and/or an output pressure generated by the fixed displacement pump towards at least one consumer circuit; a bypass valve including a valve input hydraulically connected to the delivery output of the fixed displacement pump; a reservoir hydraulically connected to the suction input of the fixed displacement pump; and a return line for receiving a return flow from the at least one consumer circuit, the return line being hydraulically connected with the bypass valve and the reservoir, wherein the bypass valve includes a variable opening for controlling the output flow or the output pressure delivered by the fixed displacement pump towards the at least one consumer circuit, and wherein the bypass valve is a proportional valve and the hydraulic circuit further comprises a relief valve in parallel with the bypass valve for connecting the delivery output of the fixed displacement pump with a reservoir when a predefined relief pressure is reached in the pressure line.

2. The hydraulic circuit according to claim 1, wherein the pump motor is of a fixed speed type.

3. The hydraulic circuit according to claim 1, wherein the pump motor is of a variable speed type.

4. The hydraulic circuit according to claim 1, wherein the hydraulic circuit comprises a filter in the return line.

5. The hydraulic circuit according to claim 4, wherein the filter in the return line is intermediate between the bypass valve and the reservoir.

6. The hydraulic circuit according to claim 1, wherein the bypass valve is a relief valve for connecting the delivery output of the fixed displacement pump with a reservoir when a controlled relief pressure is reached in the pressure line.

7. A wind turbine including a hydraulic circuit according to claim 1.

8. The wind turbine according to claim 7, wherein the hydraulic circuit is integrated in a system for controlling a pitch angle of a plurality of blades of the wind turbine.

9. The hydraulic circuit according to claim 1, wherein the at least one consumer circuit is located in parallel to the relief valve and the bypass valve.

10. The hydraulic circuit according to claim 9, wherein the output flow of the fixed displacement pump passes through only one of the consumer circuit, the relief valve and the bypass valve in completing the hydraulic circuit.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows a schematic section of a wind turbine to which the hydraulic circuit of embodiments of the present invention can be applied;

(3) FIG. 2 shows a hydraulic scheme, illustrating a first embodiment of a hydraulic circuit; and

(4) FIG. 3 shows a hydraulic scheme, illustrating a second embodiment of a hydraulic circuit.

DETAILED DESCRIPTION

(5) The illustrations in the drawings are schematic. It is noted that in different figures, similar or identical elements are provided with the same reference signs.

(6) FIG. 1 shows a wind turbine 1 according to embodiments of the invention. The wind turbine 1 comprises a tower 2, which is mounted on a non-depicted foundation. A nacelle 3 is arranged on top of the tower 2.

(7) The wind turbine 1 further comprises a wind rotor 5 having at least one blade 4 (in the embodiment of FIG. 1, the wind rotor comprises three blades 4, of which only two blades 4 are visible). The wind rotor 5 is rotatable around a rotational axis Y.

(8) The blades 4 extend substantially radially with respect to the rotational axis Y and along a respective longitudinal axis X.

(9) The wind turbine 1 comprises an electric generator 11, including a stator 20 and a rotor 30. The rotor 30 is rotatable with respect to the stator 20 about the rotational axis Y.

(10) The wind rotor 5 is rotationally coupled with the electric generator 11 either directly, e.g. direct drive or by means of a rotatable main shaft 9 and/or through a gear box (not shown in FIG. 1). A schematically depicted bearing assembly 8 is provided in order to hold in place the main shaft 9 and the rotor 5. The rotatable main shaft 9 extends along the rotational axis Y.

(11) The wind rotor 5 comprises three flanges 15 for connecting a respective blade 4 to the wind rotor 5. A pitch bearing is interposed between each blade flange 15 and the respective blade 4. A hydraulic pitch actuation system is associated to the pitch bearings of the blades 4 for regulating the pitch angle of each blade, i.e. the angular position of each blade about the respective blade longitudinal axis X.

(12) With reference to the hydraulic scheme of FIG. 2, the hydraulic pitch actuation system for controlling the pitch angle of the blades 4 comprises a hydraulic circuit 100.

(13) The hydraulic circuit 100 comprises a fixed displacement pump including a suction input and a delivery output.

(14) According to embodiments of the present invention, the fixed displacement pump may be a gear pump or a screw pump or a gerotor pump.

(15) The fixed displacement pump 110 includes a suction input 111 and a delivery output 112.

(16) The fixed displacement pump is driven by a pump motor 120.

(17) According to different embodiments of the present invention, the pump motor 120 may of the fixed speed type or of the variable speed type.

(18) The hydraulic circuit 100 comprises a pressure line 130 hydraulically connected to the delivery output 112 of the fixed displacement pump 110 for delivering an output flow generated by the fixed displacement pump 110 towards at least a consumer circuit. The pressure line 130 is interposed between the delivery output 112 and a first interface 130a of the hydraulic circuit 100 for hydraulically connecting the hydraulic circuit 100 to a consumer circuit.

(19) The hydraulic circuit 100 comprises a bypass valve 150 including a valve input 151 and a valve output 152. The valve input 151 is hydraulically connected to the delivery output 112 of the fixed displacement pump 110.

(20) The bypass valve 150 includes a variable opening for controlling the output flow delivered by the fixed displacement pump 110 towards the consumer circuit to be attached to the first interface 130a.

(21) According to embodiments of the present invention, the bypass valve 150 is a proportional valve.

(22) The hydraulic circuit 100 further comprises: a reservoir 160 hydraulically connected to the suction input 111 of the fixed displacement pump 110. a return line 170 for receiving a return flow from at least a consumer circuit.

(23) The return line 170 is interposed between the reservoir 160 and a second interface 130b of the hydraulic circuit 100 for hydraulically connecting the hydraulic circuit 100 to a consumer circuit. According to different embodiments of the present invention, the consumer circuit hydraulically connected to the return line 170 may be the same or another circuit with respect to the consumer circuit hydraulically connected to the pressure line 130.

(24) The return line 170 is hydraulically connected with the valve output 152 of the bypass valve 150 at an intermediate point 171 between the second interface 130b and the reservoir 160.

(25) The hydraulic circuit 100 may further comprise a filter 180 in the return line 170. The filter 180 is intermediate between the bypass valve 150 and the reservoir 160, in such a way that the flow exiting the valve output 152 of the bypass valve 150 reaches the reservoir 160 through the filter 180.

(26) The hydraulic circuit 100 comprises a relief valve 140 in parallel with the bypass valve 150 for connecting the delivery output 112 of the fixed displacement pump 110 with the reservoir 160 when a predefined relief pressure is reached in the pressure line 130.

(27) The bypass valve 150 and the relief valve 140 are provided in two respective branches of the hydraulic circuit 100, both connecting the pressure line 130 with the return line 170.

(28) With reference to the hydraulic scheme of FIG. 3, a second embodiment of the hydraulic circuit 100 is shown. With respect to the embodiment of FIG. 3, no proportional valve is present, but a bypass valve 190, which is a relief valve for connecting the delivery output 112 of the fixed displacement pump 110 with the reservoir 160 when a controlled relief pressure is reached in the pressure line 130. The bypass valve 190 comprises a valve input 191 is hydraulically connected to the delivery output 112 of the fixed displacement pump 110. The relief valve 190 connects the pressure line 130 with the return line 170. The opening of the bypass valve 190 is controlled for controlling the output pressure delivered by the fixed displacement pump 110 towards the consumer circuit attached to the first interface 130a.

(29) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the intention.

(30) For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.