A variable diameter engine cooling fan and engine

Abstract

The application discloses a diameter-variable engine cooling fan and engine, the cooling fan comprises a wheel disc and fan blades distributed in the circumferential direction of the wheel disc periphery, each of the fan blades is installed on the wheel disc through a hydraulic cylinder, the hydraulic cylinder comprises a cylinder body, a first piston, a second piston and a piston rod; a first oil cavity is formed between the first piston and a cylinder cover, a second oil cavity is formed between the first piston and the second piston; the second piston is a floating piston, a closed air chamber is formed between the second piston and the bottom of the cylinder body; one end of the piston rod is connected with the first piston, and the other end of the piston rod penetrates through the cylinder cover and is connected with the fan blade; a damping hole for connecting the first oil cavity and the second oil cavity is arranged on the first piston, and a power spring for driving the fan blade to reset is sleeved outside the cylinder body. The cooling fan can realize self-adaptive adjustment of the outer diameter of the fan blade.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and more particularly to engine cooling fans with variable diameters. The invention also relates to engines equipped with said cooling fans. Background Technology

[0002] The rotation of a fan generates airflow, which creates pressure fluctuations and thus generates noise. Based on the principle, noise can be divided into rotational noise and turbulent noise.

[0003] The noise level of a fan can be reduced by changing the diameter, number, shape, and angle of the fan blades. Studies have shown that the sound pressure level of a fan noise is positively correlated with the fan diameter and fan speed, while the fan airflow is also positively correlated with the fan diameter and fan speed. Therefore, in general fan design, priority is given to ensuring the heat dissipation of the engine by increasing the fan diameter. From the perspective of noise reduction, the larger the fan diameter, the higher the sound pressure level of the fan noise.

[0004] Since the main function of a fan is to cool and dissipate heat, reducing fan noise requires ensuring sufficient airflow. While adjusting the shape and number of fan blades can reduce noise levels, there are limitations. Therefore, minimizing fan noise while maintaining sufficient airflow is of great importance.

[0005] By designing a fan structure with a variable diameter, the contradiction between fan airflow and noise level can be resolved. For example, CN110131208 A discloses a hydraulically driven fan with a variable diameter and mounting angle, which includes a rotor and moving blades. The rotor and moving blades are connected by a hydraulic drive, allowing the moving blades to move radially relative to the rotor. The fan rotor also includes a moving blade mounting angle adjustment mechanism, which can adaptively adjust the mounting angle of the moving blades when they move radially relative to the rotor.

[0006] However, this adjustment structure is an active hydraulic drive, which requires the design of complex hydraulic main pipes and hydraulic branch pipes on the wheel, and the purpose of adjusting the fan diameter can only be achieved through hydraulic drive. Summary of the Invention

[0007] The purpose of this invention is to provide an engine cooling fan with a variable diameter. This cooling fan can adaptively adjust the outer diameter of the fan blades.

[0008] Another object of the present invention is to provide an engine equipped with an engine cooling fan of the aforementioned variable diameter.

[0009] To achieve the above objectives, the present invention provides a variable diameter engine cooling fan, comprising a disc and fan blades distributed circumferentially around the disc. Each fan blade is mounted on the disc via a hydraulic cylinder. The hydraulic cylinder comprises a cylinder body, a first piston, a second piston, and a piston rod. A first oil chamber is formed between the first piston and the cylinder head, and a second oil chamber is formed between the first piston and the second piston. The second piston is a floating piston, and a closed air chamber is formed between the second piston and the bottom of the cylinder body. One end of the piston rod is connected to the first piston, and the other end passes through the cylinder head and is connected to the fan blades. The first piston is provided with a damping hole connecting the first and second oil chambers. An assist spring for resetting the fan blades is fitted outside the cylinder body.

[0010] Optionally, the interior of the sealed chamber is filled with an inert gas.

[0011] Optionally, the diameter of the enclosed air chamber is larger than the diameter of the cylinder body.

[0012] Optionally, a step is formed between the sealed air chamber and the cylinder body, one end of the assist spring is connected to the step, and the other end of the assist spring is connected to the root of the fan blade.

[0013] Optionally, the root of the fan blade is provided with a flange portion with a diameter larger than that of the cylinder body, and the assist spring is connected to the flange portion.

[0014] Optionally, the thickness of the second piston gradually decreases from the edge to the center.

[0015] Optionally, the side of the second piston opposite to the first piston is a flat surface, and the side of the second piston opposite to the first piston is a concave arc surface.

[0016] Optionally, the inner wall of the cylinder is provided with a first limiting step, and the outer periphery of the second piston is provided with a second limiting step corresponding to the first limiting step.

[0017] Optionally, the damping orifice extends through the first piston along the direction of movement of the first piston; and / or, the length of the enclosed air chamber is 1 / 4 to 1 / 8 of the length of the cylinder.

[0018] To achieve the other objective mentioned above, the present invention provides an engine, including an engine body and a cooling fan disposed on the engine body, wherein the cooling fan is a variable diameter engine cooling fan as described in any of the preceding claims.

[0019] The variable-diameter engine cooling fan provided by this invention has two pistons inside its hydraulic cylinder. The first piston separates a first oil chamber and a second oil chamber, while the second piston is a floating piston that separates the second oil chamber from a closed air chamber. A damping orifice is provided on the first piston. When the fan rotates at a high speed, under the action of centrifugal force, the first piston moves outward along with the fan blades. Hydraulic oil from the first oil chamber enters the second oil chamber through the damping orifice. Simultaneously, the second piston moves in the direction of increasing the volume of the closed air chamber to compensate for the change in hydraulic oil chamber volume caused by the outward extension of the piston rod. When the fan rotates at a low speed, under the action of the assist spring and the closed air chamber, the first piston moves inward along with the fan blades. Hydraulic oil from the second oil chamber enters the first oil chamber through the damping orifice. Simultaneously, the second piston moves in the direction of restoring the volume of the closed air chamber to compensate for the change in hydraulic oil chamber volume caused by the inward retraction of the piston rod.

[0020] This allows for adaptive adjustment of the fan blade outer diameter, enabling an increase in fan diameter to provide maximum heat dissipation under demanding engine cooling conditions, i.e., at high speeds. Conversely, it allows for a decrease in fan diameter at medium and low speeds, reducing fan noise and overall fuel consumption. This adaptive diameter adjustment method eliminates the need for complex hydraulic piping or hydraulic pumps; it utilizes centrifugal force to move the blades and uses a sealed air chamber and assist springs for resetting. This design offers advantages such as simple structure, stable performance, and ease of maintenance. Attached Figure Description

[0021] Figure 1 A schematic diagram of a variable diameter engine cooling fan provided in an embodiment of the present invention;

[0022] Figure 2 This is a cross-sectional view showing the connection between the fan blades, hydraulic cylinder, and wheel.

[0023] Figure 3 for Figure 2 A magnified view of a portion of the image.

[0024] In the picture:

[0025] 10. Wheel; 20. Fan blade; 21. Flange; 30. Hydraulic cylinder; 31. Cylinder body; 310. Stepped section; 311. First limiting step; 32. Cylinder head; 33. First piston; 331. Damping hole; 34. Second piston; 341. Second limiting step; 35. Piston rod; 40. Bolt; 50. Assist spring. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] In this document, terms such as "upper," "lower," "inner," and "outer" are established based on the positional relationships shown in the accompanying drawings. Depending on the drawings, the corresponding positional relationships may also change. Therefore, they should not be interpreted as an absolute limitation on the scope of protection. Moreover, relational terms such as "first" and "second" are only used to distinguish one component from another that has the same name, and do not necessarily require or imply any such actual relationship or order between these components.

[0028] Please refer to Figures 1 to 3 , Figure 1 A schematic diagram of a variable diameter engine cooling fan provided in an embodiment of the present invention; Figure 2 This is a cross-sectional view showing the connection between the fan blades, hydraulic cylinder, and wheel. Figure 3 for Figure 2 A magnified view of a portion of the image.

[0029] In one specific embodiment, the variable diameter engine cooling fan provided by the present invention mainly consists of a disc 10 located at the center and a plurality of fan blades 20 distributed around the disc in the circumferential direction. The root of each fan blade 20 is respectively mounted on the disc 10 by a hydraulic cylinder 30.

[0030] In order to reduce fan noise by reducing fan diameter while ensuring fan airflow, hydraulic cylinder 30 is mainly composed of cylinder body 31, cylinder head 32, first piston 33, second piston 34 and piston rod 35. The cylinder body 31 is filled with hydraulic oil. The first piston 33 and cylinder head 32 form a first oil chamber a, the first piston 33 and second piston 34 form a second oil chamber b, the second piston 34 is a floating piston, and the second piston 34 and the bottom of cylinder body 31 form a closed air chamber c.

[0031] Specifically, one end of the piston rod 35 is connected to the first piston 33 and fixed to the first piston 33 by bolts 40, and the other end passes through the cylinder head 32 and is connected to the root of the fan blade 20. The first piston 33 is provided with damping holes 331 that connect the first oil chamber a and the second oil chamber b. There are multiple damping holes 331, which are evenly distributed on the first piston 33 along the circumferential direction and pass through the first piston 33 along the moving direction of the first piston 33.

[0032] The diameter of the closed air chamber c is larger than the diameter of the cylinder 31. It is filled with inert gas. Along the length of the piston rod 35, the length of the closed air chamber c is 1 / 4 to 1 / 8 of the length of the cylinder 31.

[0033] A booster spring 50 is fitted on the outside of the hydraulic cylinder 30 to drive the fan blade 20 to return to its original position. A step portion 310 is formed between the closed air chamber c and the cylinder body 31. One end of the booster spring 50 is connected to the step portion 310. The root of the fan blade 20 is provided with a flange portion 21 with a diameter larger than that of the cylinder body. The other end of the booster spring 50 is connected to the flange portion 21. The fan blade 20 can cover one end of the hydraulic cylinder 30 through the flange portion 21, thereby limiting the retraction distance.

[0034] The thickness of the second piston 34 gradually decreases from the edge to the middle. The side of the second piston 34 opposite to the first piston 33 is a flat surface, while the side of the second piston 34 away from the first piston 33 is a concave arc surface. The inner wall of the cylinder body 31 is provided with a first limiting step 311, and the outer periphery of the second piston 34 is provided with a second limiting step 341 corresponding to the first limiting step 311. Under the restriction and guidance of the limiting steps, the second piston 34 can float left and right within a certain range, thereby changing the volume of the closed air chamber c and compensating for the volume change of the hydraulic oil chamber caused by the piston rod 35 entering and exiting. During the floating process, the outer periphery of the second piston 34 and the inner wall of the cylinder body 31 are always sealed.

[0035] The second piston 34 can float by moving, by deforming, or by a combination of both. For example, in other embodiments, the second piston 34 can be made of a flexible material. If a flexible material is used, the second piston 34 can undergo moderate deformation when it floats to its limit position as the piston rod 35 enters or exits the cylinder 31. This deformation can further increase or decrease the volume of the closed air chamber c to compensate for the volume change of the hydraulic oil chamber caused by the piston rod 35 entering and exiting.

[0036] Rotational noise, also known as discrete noise, is noise with discrete frequencies caused by the periodic compression of air particles by rotating blades, resulting in pressure pulsations.

[0037] Turbulent noise is a type of broadband noise caused by the eddies generated during the interaction between the blades and the airflow during the operation of a fan, resulting from the boundary separation of the airflow.

[0038] Eddy noise is formed by the interaction between the blade wall and turbulence. When the vibration frequency caused by the eddy is close to the natural frequency of the blade, resonance will occur, which will greatly increase the noise. In severe cases, it will cause the blade to break. Eddy noise mainly depends on the fan's operating conditions such as blade shape, rotational speed, airflow, and air resistance.

[0039] The aerodynamic noise generated by the fan can be initially assessed using the following sound pressure level formula:

[0040]

[0041]

[0042] In the formula: △SPL is the sound pressure level difference; △PWL is the sound power; d1 is the outer diameter of fan 1, d2 is the outer diameter of fan 2; n1 is the rotational speed of fan 1, n2 is the rotational speed of fan 2.

[0043] As can be seen from the above formula, if the fan shroud and other parameters remain unchanged, reducing the outer diameter of the fan is one of the important ways to reduce fan noise.

[0044] The aforementioned variable diameter engine cooling fan has two pistons inside its hydraulic cylinder 30. The first piston 33 is used to separate the first oil chamber a and the second oil chamber b, and the second piston 34 is a floating piston used to separate the second oil chamber b from the closed air chamber c. Meanwhile, the first piston 33 is provided with a damping hole 331.

[0045] In actual operation, when the fan rotates at a high speed, under the action of centrifugal force, the first piston 33 can move outward together with the fan blade 20. The hydraulic oil in the first oil chamber a enters the second oil chamber c through the damping hole 331. At the same time, the second piston 34 moves in the direction of increasing the volume of the closed air chamber c to compensate for the change in the volume of the hydraulic oil chamber caused by the piston rod 35 extending outward. When the fan rotates at a low speed, under the action of the assist spring 50 and the closed air chamber c, the first piston 33 moves inward together with the fan blade 20. The hydraulic oil in the second oil chamber b enters the first oil chamber a through the damping hole 331. At the same time, the second piston 34 moves in the direction of restoring the volume of the closed air chamber c to compensate for the change in the volume of the hydraulic oil chamber caused by the piston rod 35 retracting inward.

[0046] In this way, the outer diameter of the fan blades can be adaptively adjusted. In the high-speed range, the fan diameter can be increased to ensure the engine's cooling needs, while in the medium and low-speed range, the fan diameter can be reduced to reduce fan noise and overall fuel consumption. It does not require the design of complex hydraulic lines or hydraulic pumps. It only uses centrifugal force to move the blades and uses a closed air chamber and a booster spring to reset them. The structure is simple, the performance is stable, and it is easy to maintain.

[0047] The above embodiments are merely preferred embodiments of the present invention and are not limited thereto. Based on these, targeted adjustments can be made according to actual needs to obtain different implementation methods. For example, the hydraulic cylinder 30 and the wheel 10 can be an integral structure, or the root of the fan blade 20 can be designed into other shapes, and so on. Since there are many possible implementation methods, they will not be listed here.

[0048] In addition to the aforementioned variable-diameter engine cooling fan, the present invention also provides an engine, specifically a diesel engine, having an engine block and a cooling fan disposed on the engine block, wherein the cooling fan is the variable-diameter engine cooling fan described above. For the remaining structure of the diesel engine, please refer to the prior art, which will not be repeated here.

[0049] The diesel engine is equipped with the aforementioned variable-diameter engine cooling fan, which can balance fan noise level and cooling capacity. The cooling fan uses centrifugal force, a closed air chamber, and a booster spring to extend and retract the fan blade diameter, thereby reducing noise at low and medium speeds of the diesel engine and meeting the fan airflow requirements at high speeds.

[0050] The variable-diameter engine cooling fan and engine provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A variable diameter engine cooling fan, comprising a disc (10) and fan blades (20) distributed circumferentially around the disc (10), characterized in that, Each of the fan blades (20) is mounted on the wheel disc (10) via a hydraulic cylinder (30). The hydraulic cylinder (30) includes a cylinder body (31), a first piston (33), a second piston (34), and a piston rod (35). A first oil chamber a is formed between the first piston (33) and the cylinder head (32), and a second oil chamber b is formed between the first piston (33) and the second piston (34). The second piston (34) is a floating piston, and a closed air chamber c is formed between the second piston (34) and the bottom of the cylinder body (31). One end of the piston rod (35) is connected to the first piston (33), and the other end passes through the cylinder head (32) and is connected to the fan blade (20). The first piston (33) is provided with a damping hole (331) connecting the first oil chamber a and the second oil chamber b. An assist spring (50) for driving the fan blade (20) to reset is fitted on the outside of the cylinder body (31). The diameter of the closed air chamber c is larger than the diameter of the cylinder body (31). The thickness of the two pistons (34) gradually decreases from the edge to the middle. When the fan rotates at a high speed, under the action of centrifugal force, the first piston (33) can move outward together with the fan blade (20). The hydraulic oil in the first oil chamber a enters the second oil chamber c through the damping hole (331). At the same time, the second piston (34) moves in the direction of increasing the volume of the closed air chamber c to compensate for the change in the volume of the hydraulic oil chamber caused by the piston rod (35) extending outward. When the fan rotates at a low speed, under the action of the assist spring (50) and the closed air chamber c, the first piston (33) moves inward together with the fan blade (20). The hydraulic oil in the second oil chamber b enters the first oil chamber a through the damping hole (331). At the same time, the second piston (34) moves in the direction of restoring the volume of the closed air chamber c to compensate for the change in the volume of the hydraulic oil chamber caused by the piston rod (35) retracting inward. This achieves adaptive adjustment of the outer diameter of the fan blades, uses the action of centrifugal force to move the blades, and uses the closed air chamber and assist spring to reset them.

2. The variable diameter engine cooling fan according to claim 1, characterized in that, The sealed gas chamber c is filled with inert gas.

3. The variable diameter engine cooling fan according to claim 1, characterized in that, A step portion (310) is formed between the closed air chamber c and the main body of the cylinder (31). One end of the assist spring (50) is connected to the step portion (310), and the other end of the assist spring (50) is connected to the root of the fan blade (20).

4. The variable diameter engine cooling fan according to claim 3, characterized in that, The root of the fan blade (20) is provided with a flange (21) with a diameter larger than that of the cylinder body (31), and the power spring (50) is connected to the flange (21).

5. The variable diameter engine cooling fan according to claim 1, characterized in that, The side of the second piston (34) opposite to the first piston (33) is a flat surface, and the side of the second piston (34) opposite to the first piston (33) is a concave arc surface.

6. The variable diameter engine cooling fan according to claim 5, characterized in that, The inner wall of the cylinder (31) is provided with a first limiting step (311), and the outer periphery of the second piston (34) is provided with a second limiting step (341) corresponding to the first limiting step (311).

7. The variable diameter engine cooling fan according to any one of claims 1 to 6, characterized in that, The damping orifice (331) extends through the first piston (33) along the direction of movement of the first piston (33); and / or, the length of the closed air chamber c is 1 / 4 to 1 / 8 of the length of the cylinder (31).

8. An engine, comprising an engine block and a cooling fan disposed on the engine block, characterized in that, The cooling fan is an engine cooling fan with a variable diameter as described in any one of claims 1 to 7.

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