EP-4274780-B1 - MULTI-STAGE PROPELLER SYSTEM

Inventors

• ABDALLAH, SHAABAN

Dates

Publication Date

20260506

Application Date

20220107

Claims (9)

1. A propulsion system (50; 90) comprising: a first propeller (52); a second propeller (54); and a third propeller (56); a first motor (60); and a second motor (64), wherein the first propeller (52), the second propeller (54), and the third propeller (56) are arranged to rotate about a common axis (CA) and the second propeller (54) is disposed between the first propeller (52) and the third propeller (56), and wherein the first propeller (52) and the third (56) are configured to rotate about the common axis (CA) in a first direction (A) and the second propeller (54) is configured to rotate about the common axis (CA) in a second direction (B) opposite to the first direction (A), characterized in that the first motor (60) is coupled to the first and third propellers (52; 56) and configured to rotate the first and third propellers (52; 56) in the first direction (A), and the second motor (64) is coupled to the second propeller (54) and configured to rotate the second propeller (54) in the second direction (B).
2. The propulsion system of claim 1, further comprising: a first shaft (58) and a second shaft (62) arranged along the common axis (CA), wherein the first propeller (52) and the third propeller (56) are coupled to the first shaft (58) and the second propeller (54) is coupled to the second shaft (62).
3. The propulsion system of claim 1, wherein the first motor (60) and second motor (64) are arranged along the common axis (CA), the first motor (60) being disposed between the first propeller (52) and the second propeller (54) and the second motor (64) being disposed between the second propeller (54) and the third propeller (56).
4. The propulsion system of claim 1, wherein the first motor (60) and second motor (64) are arranged along the common axis (CA), the first motor (60) and the second motor (64) being disposed between the second propeller (54) and the third propeller (56).
5. The propulsion system of claim 1, wherein the first propeller (52) has a diameter D1, the second propeller (54) has a diameter D2, and the third propeller (56) has a diameter D3, wherein diameter D1 is greater than diameter D2 and diameter D2 is greater than diameter D3.
6. The propulsion system of claim 1, further comprising a motor control unit (66) operatively coupled to the first motor (60) and the second motor (64), the motor control unit (66) configured to independently control a rotational speed of the first motor (60) and a rotational speed of the second motor (64).
7. An aircraft (40) having a body comprising: a propulsion system (50; 90) in accordance with claim 1 coupled to the body.
8. The aircraft of claim 7, further comprising: a first shaft (58) and a second shaft (62) arranged along the common axis (CA), wherein the first propeller (52) and the third propeller (56) are coupled to the first shaft (58) and the second propeller (54) is coupled to the second shaft (62).
9. The aircraft of claim 7, wherein the first propeller (52) has a diameter D1, the second propeller (54) has a diameter D2, and the third propeller (56) has a diameter D3, wherein diameter D1 is greater than diameter D2 and diameter D2 is greater than diameter D3.

Description

Cross Reference to Related Application This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63/134,698, filed January 7, 2021. Technical Field The invention relates generally to propulsion systems using counter-rotating propellers. Background Aircraft such as airplanes, helicopters, and unmanned air vehicles commonly use propulsion systems with propellers to provide thrust for the aircraft. Some aircraft propulsion systems will employ counter-rotating propellers to improve the efficiency and thrust of that propulsion system compared to propulsion systems with only one propeller. Typically, the counter-rotating propellers are mounted on concentric shafts and rotated by a common motor, such that both propellers turn at the same revolutions per minute (RPM). The motor may be an internal combustion engine, an electric motor, or a hybrid motor using fuel and batteries. A propulsion system having the features of the preamble of present claim 1 is described in US 2020/223539 A1. Further propulsion systems are disclosed in CN 208 715 470 U and US 9 815 552 B1. Such counter-rotating propellers are often optimized for a particular flight regime, such as for maximum takeoff thrust or maximum efficiency at cruise. The efficiency and thrust gains achieved by the counter-rotating propellers, however, decrease when the counter-rotating propellers are operating in non-optimized regimes, sometimes referred to as "off design". Propulsion systems using counter-rotating propellers are generally more complex, heavier, and more costly to build and maintain compared to their single propeller counterparts. Thus, to be commercially viable, a propulsion system with counter-rotating propellers needs to be more efficient and provide thrust/lift gains over a wide operating regime. If the gains of a propulsion system with counter-rotating propellers are restricted to a narrow operating regime, then the disadvantages of such a propulsion system may outweigh its benefits. What is needed therefore is a propulsion system with counter-rotating propellers that provides increased efficiency and/or increased thrust over a wide operating regime. Summary Of The Invention To these and other ends, a propulsion system includes a first propeller; a second propeller; and a third propeller, wherein the first propeller, the second propeller, and the third propeller are arranged to rotate about a common axis and the second propeller is disposed between the first propeller and the third propeller. The first propeller and the third are configured to rotate about the common axis in a first direction and the second propeller is configured to rotate about the common axis in a second direction opposite to the first direction. This propulsion system further includes a first motor and a second motor. The first motor is coupled to the first and third propellers and configured to rotate the first and third propellers in the first direction, and the second motor is coupled to the second propeller and configured to rotate the second propeller in the second direction. In one aspect of this embodiment, the propulsion system may further include a first shaft and a second shaft arranged along the common axis, wherein the first propeller and the third propeller are coupled to the first shaft and the second propeller is coupled to the second shaft. In another aspect of this embodiment, the first motor and second motor are arranged along the common axis, wherein the first motor is disposed between the first propeller and the second propeller and the second motor is disposed between the second propeller and the third propeller. In yet another aspect of this embodiment, the first motor and second motor are arranged along the common axis, the first motor and the second motor being disposed between the second propeller and the third propeller. In another aspect of this embodiment, the propulsion system further includes a motor control unit operatively coupled to the first motor and the second motor. The motor control unit is configured to independently control a rotational speed of the first motor and a rotational speed of the second motor. In an embodiment, the first propeller has a diameter D1, the second propeller has a diameter D2, and the third propeller has a diameter D3, wherein diameter D1 is greater than diameter D2 and diameter D2 is greater than diameter D3. In an embodiment, an aircraft having a body includes a propulsion system coupled to the body. The propulsion includes a first propeller; a second propeller; and a third propeller, wherein the first, second, and third propellers are arranged to rotate about a common axis such that the second propeller is disposed between the first propeller and the third propeller. The first propeller and the third are configured to rotate about the common axis in a first direction and the second propeller is configured to rotate about the common axis in a second direction opposite to