ENGINE COOLING FANS WITH UNEVEN BLADE SPACING

Abstract

Methods and systems are provided for a fan. In one example, a fan may include a plurality of blades separated by spacings. The spacing is one of a small blade spacing, a medium blade spacing, and a large blade spacing. The size as well as the arrangement of the small, medium, and the large blade spacings are determined by minimizing an imbalance force and pressure generated by the fan at a plurality of frequencies.

Description

FIELD

The present description relates generally to methods and systems of a fan with uneven blade spacing.

BACKGROUND/SUMMARY

Engine cooling fans may cause noise, vibration, and harshness (NVH) due to their large size, high power, and excessive engagement during vehicle operation. Rotation of the cooling fan may generate tonal noise and vibrations at various frequencies including a fundamental frequency (or a first order imbalance) and harmonic frequencies.

One approach to address the NVH issue include arranging the fan blades with non-uniform spacing. One example approach is shown by Delvaux, et al. in U.S. Pat. No. 8,678,752. Therein, fan blades are separated with spacers of different sizes. The spacers may be arranged in a variety of repeating patterns, or in a random order.

However, the inventors herein have recognized potential issues with such systems. As one example, though non-uniform spacing may change the frequency distribution of NVH by spreading the harmonics over a wider frequency range, the asymmetric blade arrangement may increase NVH due to an increased imbalance force. The imbalance force may generate boom noise and vibrations at the seat track and the steering wheel. Additionally, the size and the arrangement of the spacers may affect the frequency distribution of NVH and the imbalance force. The search for the spacer arrangement with minimal imbalance force and preferred frequency distribution may be difficult due to the large number of possible spacer arrangements. The possible combinations of spacer arrangements may increase exponentially with the number of the fan blades. As one example, a fan with n blades and spacers of r sizes may have n!/(n-r)! possible combinations of spacer arrangement. As another example, if the fan has six blades and spacers of three sizes, there are over 13 million unique combinations of spacer arrangements. If the fan has seven blades and spacers of three sizes, there are over 580 million unique combinations of spacer arrangements.

In one example, the issues described above may be addressed by a fan including blades disposed circumferentially around a hub. The adjacent blades may be separated by the spacing selected from one of a small blade spacing S, a medium blade spacing M, and a large blade spacing L. In one embodiment, the fan may include six blades. The fan may include two small blade spacings, two medium blade spacings, and two large blade spacings, wherein the medium blade spacing is smaller than the large blade spacing and larger than the small blade spacing. In another embodiment, the fan may include seven blades. The fan may include one medium blade spacing, at least two small blade spacings adjacent to each other, and at least two large blade spacings. In another embodiment, the fan may include eight blades. The fan may include a plurality of small blade spacings and a plurality of large blade spacings arranged in the sequence of LLSSL. In yet another embodiment, the fan may include nine blades. The fan may include a plurality of small blade spacings and a plurality of large blade spacings arranged in a sequence of LLSS. In this way, NVH from fan with uneven blade spacing may be minimized.

As one example, the fan may be designed with uneven spacing between adjacent blades. The spacing may be selected among a small blade spacing, a medium blade spacing, and a large blade spacing. The size of the small, medium, and large blade spacings, as well as the sequence of arrangement of the blade spacings circumferentially relative to the hub of the fan, may be determined through an optimization process that recognizes only certain harmonics should be minimized. Further, the optimization process minimizes the imbalance force that caused by uneven blade spacing. During optimization, a frequency distribution of pressure generated by a rotating fan, as well as the imbalance force, are calculated. The optimal size and arrangement of the blade spacings may be determined by minimizing the magnitude of the imbalance force and the magnitude of the pressure at one or more selected harmonic frequencies, while ignoring other frequencies and harmonics. By analyzing the pressure at selected frequencies, the computation burden is reduced. Further, NVH generated at the objectionable harmonics as well as the imbalance force may be significantly reduced in a vehicle application due to the fact that certain frequencies contribute more to customer annoyance than others depending on the relative magnitudes of the harmonics.

It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of a cooling system in a motor vehicle.

FIG. 2 is an example method for determining the arrangement of blades of a fan.

FIG. 3 illustrates example results of an optimization process for a six-blade fan.

FIG. 4A shows one example of a fan with six blades.

FIG. 4B shows another example of a fan with six blades.

FIG. 5A shows one example of a fan with seven blades.

FIG. 5B shows another example of a fan with seven blades.

FIG. 6A shows one example of a fan with eight blades.

FIG. 6B shows another example of a fan with eight blades.

FIG. 7A shows one example of a fan with nine blades.

FIG. 7B shows another example of a fan with nine blades.

FIG. 7C shows another example of a fan with nine blades.

DETAILED DESCRIPTION

The following description relates to systems and methods for a fan with uneven spacing between adjacent blades. For example, the fan may be a cooling fan of a cooling system coupled to a vehicle, as shown in FIG. 1. The spacings between blades may be selected from the small, medium, and large blade spacings. The size of each blade spacing and the arrangement of these blade spacings around the hub may be determined through an optimization process shown in FIG. 2. The optimization process minimizes the imbalance force and pressure generated by the fan at various frequencies. FIG. 3 shows example results of the optimization process for a six-blade fan. Structure of fan with optimized blade arrangement is shown in FIGS. 4A-4B, 5A-5B, 6A-6B, and 7A-7C. FIGS. 4A-4B shows two examples of six-blade fans. FIGS. 5A-5B shows two examples of seven-blade fans. FIGS. 6A-6B shows two examples of eight-blade fans. FIGS. 7A-4C shows three examples of nine-blade fans.

FIG. 1 is a schematic depiction of an example embodiment of vehicle cooling system 100 in vehicle 102. Vehicle 102 has drive wheels 106, a passenger compartment 104, and an under-hood compartment 103. Under-hood compartment 103 may house various under-hood components under the hood (not shown) of motor vehicle 102. For example, under-hood compartment 103 may house internal combustion engine 10. Internal combustion engine 10 has a combustion chamber which may receive intake air via intake passage 44 and may exhaust combustion gases via exhaust passage 48. In one example, intake passage 44 may be configured as a ram-air intake wherein the dynamic pressure created by moving vehicle 102 may be used to increase a static air pressure inside the engine's intake manifold. As such, this may allow a greater mass flow of air through the engine, thereby increasing engine power. Engine 10 as illustrated and described herein may be included in a vehicle such as a road automobile, among other types of vehicles. While the example applications of engine 10 will be described with reference to a vehicle, it should be appreciated that various types of engines and vehicle propulsion systems may be used, including passenger cars, trucks, etc.

Cooling system 100 may circulate coolant through internal combustion engine 10 to absorb waste heat, and distributes the heated coolant to radiator 80 and/or heater core 55 via coolant lines 82 and 84, respectively. In one example, as depicted, cooling system 100 may be coupled to engine 10 and may circulate engine coolant from engine 10 to radiator 80 via engine-driven water pump 86, and back to engine 10 via coolant line 82. Engine-driven water pump 86 may be coupled to the engine via front end accessory drive (FEAD) 36, and rotated proportionally to engine speed via a belt, chain, etc. Specifically, engine-driven water pump 86 may circulate coolant through passages in the engine block, head, etc., to absorb engine heat, which is then transferred via the radiator 80 to ambient air. In one example, where engine-driven water pump 86 is a centrifugal pump, the pressure (and resulting flow) produced by the pump may be proportional to the crankshaft speed, or may be directly proportional to the engine speed. The temperature of the coolant may be regulated by a thermostat valve 38, located in the cooling line 82, which may be kept closed until the coolant reaches a threshold temperature.

Coolant may flow through coolant line 82, as described above, and/or through coolant line 84 to heater core 55 where the heat may be transferred to passenger compartment 104, and the coolant flows back to engine 10. In some examples, engine-driven pump 86 may operate to circulate the coolant through both coolant lines 82 and 84.

One or more blowers and cooling fans may be included in cooling system 100 to provide airflow assistance and augment a cooling airflow through the under-hood components. For example, cooling fan 91, coupled to radiator 80, may be operated when the vehicle is moving and the engine is running to provide cooling airflow assistance through radiator 80. Cooling fan 91 may draw a cooling airflow into under-hood compartment 103 through an opening in the front-end of vehicle 102, for example, through grill 112. Such a cooling air flow may then be utilized by radiator 80 and other under-hood components (e.g., fuel system components, batteries, etc.) to keep the engine and/or transmission cool. Further, the air flow may be used to reject heat from a vehicle air conditioning system. Further still, the airflow may be used to improve the performance of a turbocharged/supercharged engine that is equipped with intercoolers that reduce the temperature of the air that goes into the intake manifold/engine. While this embodiment depicts one cooling fan, other examples may use multiple cooling fans.

Cooling fan 91 may be coupled to battery driven motor 93. During engine operation, the engine generated torque may be transmitted to electric machine 52 along a drive shaft, which may then be used by the electric machine 52 to generate electrical power that may be stored in an electrical energy storage device, such as battery 58. Battery 58 may then be used to activate motor 93 via relays (not shown). Thus, operating the cooling fan system may include electrically powering cooling fan rotation from engine rotational input, through the alternator and system battery, for example, when engine speed is below a threshold (for example, when the engine is in idle-stop). In other embodiments, the cooling fan may be operated by enabling a variable speed electric motor coupled to the cooling fan. In still other embodiments, cooling fan 91 may be mechanically coupled to engine 10 via a clutch (not shown) and operating the cooling fans may include mechanically powering their rotation from engine rotational output via the clutch.

Under-hood compartment 103 may further include an air conditioning (AC) system comprising condenser 88, compressor 87, receiver drier 83, expansion valve 89, and evaporator 85 coupled to a blower (not shown). Compressor 87 may be coupled to engine 10 via FEAD 36 and electromagnetic clutch 76 (also known as compressor clutch 76) which allows the compressor to engage or disengage from the engine based on when the air conditioning system is turned on and switched off. Compressor 87 may pump pressurized refrigerant to condenser 88 mounted at the front of the vehicle. Condenser 88 may be cooled by cooling fans 91 and 95, thereby, cooling the refrigerant as it flows through. The high pressure refrigerant exiting condenser 88 may flow through receiver drier 83 where any moisture in the refrigerant may be removed by the use of desiccants. Expansion valve 89 may then depressurize the refrigerant and allow it to expand before it enters evaporator 85 where it may be vaporized into gaseous form as passenger compartment 104 is cooled. Evaporator 85 may be coupled to a blower fan operated by a motor (not shown) which may be actuated by system voltage.

System voltage may also be used to operate an entertainment system (radio, speakers, etc.), electrical heaters, windshield wiper motors, rear window defrosting system and headlights amongst other systems.

FIG. 1 further shows a control system 14. Control system 14 may be communicatively coupled to various components of engine 10 to carry out the control routines and actions described herein. For example, as shown in FIG. 1, control system 14 may include an electronic digital controller 12. Controller 12 may be a microcomputer, including a microprocessor unit, input/output ports, an electronic storage medium for executable programs and calibration values, random access memory, keep alive memory, and a data bus. As depicted, controller 12 may receive input from a plurality of sensors 16, which may include user inputs and/or sensors (such as transmission gear position, gas pedal input, brake input, transmission selector position, vehicle speed, engine speed, ambient temperature, intake air temperature, etc.), cooling system sensors (such as coolant temperature, fan speed, passenger compartment temperature, ambient humidity, etc.), and others (such as Hall Effect current sensors from the alternator and battery, system voltage regulator, etc.). Further, controller 12 may communicate with various actuators 18, which may include engine actuators (such as fuel injectors, an electronically controlled intake air throttle plate, spark plugs, etc.), cooling system actuators (such as motor circuit relays, etc.), and others. The controller 12 employs the various actuators of FIG. 1 to adjust engine operation based on the received signals and instructions stored on a memory of the controller. In some examples, the storage medium may be programmed with computer readable data representing instructions executable by the processor for performing the methods described below as well as other variants that are anticipated but not specifically listed.

Engine controller 12 may adjust the operation of cooling fan 91 to control air flow through radiator 80 based on vehicle cooling demands, vehicle operating conditions, and in coordination with engine operation by actuating motor 93. In one example, during a first vehicle moving condition, when the engine is operating, and vehicle cooling and airflow assistance from the fan is desired, cooling fan 91 may be powered by enabling battery-driven electric motor 93 to provide airflow assistance in cooling under-hood components. The first vehicle moving condition may include, for example, when an engine temperature is above a threshold. In another example, during a second vehicle moving condition, when airflow assistance is not desired (for example, due to sufficient vehicle motion-generated airflow through the under-hood compartment), fan operation may be discontinued by disabling the fan motor. In another example, during a third vehicle moving condition when an air conditioner is operational, cooling fan 91 may be activated to enable cooling of air conditioner condenser 88.

In some examples, vehicle 102 may be a hybrid vehicle with multiple sources of torque available to one or more vehicle wheels 106. In other examples, vehicle 102 is a conventional vehicle with only an engine, or an electric vehicle with only electric machine(s). In the example shown, vehicle 102 includes engine 10 and an electric machine 52. Electric machine 52 may be a motor or a motor/generator. Crankshaft 140 of engine 10 and electric machine 52 are connected via a transmission 54 to vehicle wheels 106 when one or more clutches 56 are engaged. In the depicted example, a first clutch 56 is provided between crankshaft 140 and electric machine 52, and a second clutch 56 is provided between electric machine 52 and transmission 54. Controller 12 may send a signal to an actuator of each clutch 56 to engage or disengage the clutch, so as to connect or disconnect crankshaft 140 from electric machine 52 and the components connected thereto, and/or connect or disconnect electric machine 52 from transmission 54 and the components connected thereto. Transmission 54 may be a gearbox, a planetary gear system, or another type of transmission. The powertrain may be configured in various manners including as a parallel, a series, or a series-parallel hybrid vehicle.

Electric machine 52 receives electrical power from battery 58 to provide torque to vehicle wheels 106. Electric machine 52 may also be operated as a generator to provide electrical power to charge battery 58, for example during a braking operation.

FIG. 2 shows flow chart of an example method 200 for determining blade arrangement of a fan. In one example, the spacing between adjacent blades may be selected from one of the small, medium, and large spacings. The size of the small, medium, and large spacings, as well as the sequence of arrangement of these spacings circumferentially around the fan hub may be determined through an optimization process. In the optimization process, the imbalance force and the pressure at selected frequencies generated by the rotating fan are minimized to reduce the NVH caused by the first order imbalance force and high order harmonic noises.

At 202, the number of fan blades n is determined. As an example, the number of blade may be determined by parameters including radiator dimension, desired air flow rate, and desired air flow volume.

At 204, boundary conditions are determined. The boundary conditions may include the range of the blade spacings. For example, the spacing between two adjacent blades ΔB_i may be selected from three ranges including the small blade spacing S, the medium blade spacing M, and the large blade spacing L:

$\begin{array}{cc}\Delta B_i\in \left\{S,M,L\right\},i\in \left\{1\dots n\right\},\frac{360}{n}-\alpha \frac{\delta }{2}<M<\frac{360}{n}+\alpha \frac{\delta }{2},\alpha \in \left(0,1\right],\frac{360}{n}-\delta \le S\le \frac{360}{n}-\frac{\delta }{2},\frac{360}{n}+\frac{\delta }{2}\le L\le \frac{360}{n}+\delta ,\delta \in \left(0,10\right],& \mathrm{Condition}1\end{array}$

wherein Δ is a deviation angle from a nominal value

$\frac{360}{n}.$

The range of me deviation δ may be determined based on the fan performance and the durability of the rotor. The coefficient α is determined based on the pattern of the optimal designs, and varies responsive to the number of blades. As an example, for each fan, the size of blading spacing within the same range (i.e., within the same small, medium, or large blade spacing) does not have to be exactly the same but should meet Condition 1. As another example, the size of blading spacing in the same range is the same.

The boundary conditions may further include that the total spacings of the fan is 360 degrees:

Σ_i=1ⁿΔB_i=360.   Condition 2

At 206, a screening DOE (design of experiments) table is initiated to explore the full design space. The screening DOE table may include the blade arrangement. The blade arrangement may include the size and sequence of blade spacing between each adjacent blades around the hub. The screening DOE table may also include the imbalance force and the magnitude of pressure at selected frequencies for the blade arrangement. In one example, the frequencies may be selected to be objectionable fan tonal frequencies. The frequencies may be selected based on the frequency range of human ear sensitivity and the frequency range of the engine noise. For example, the frequencies may be selected to be lower than the frequency of engine noise and within the range of human ear sensitivity. In one embodiment, the selected frequencies may include the third harmonic frequency. In another embodiment, the selected frequencies may include each and every of the third harmonic frequency, the fourth harmonic frequency, and the fifth harmonic frequency.

In one embodiment, method 200 may initiate the screening DOE table by setting the size of blade spacing between each adjacent blades to be

$\frac{360}{n}.$

Further, method 200 may set the imbalance force and the pressure at selected frequencies to a large number.

At 208, the pressure and the imbalance force for a most recently generated blade arrangement are calculated. The blade arrangement may be the initiated blade arrangement at 206, responsive to the initiation of the screening DOE table. The blade arrangement may alternatively be a newly generated blade arrangement in a design optimization table.

In one embodiment, when calculating the pressure and the imbalance force, it may be assumed that all blades are identical in size, shape, and pitch; and each blade generates the same centrifugal force when the fan rotates. Further, it may be assumed that each blade generates the same triangular pressure pulse. The air pressure generated by rotating the fan may be calculated by taking Fourier transformation of the pressure pulses. The imbalance force may be calculated as a function of the rotation speed of the fan, the blade arrangement, and the mass of the blade. In one example, the imbalance force may be the sum of force generated by each blade in one revolution.

At 210, method 200 calculates a cost function based on the imbalance force and magnitude of pressure generated by the rotating fan at the frequencies determined at 206. As one example, magnitude of pressure at the selected frequencies determined at 206 are identified. In one embodiment, the cost function may be constructed as a weighted sum of the pressure magnitudes at the selected frequencies, as well as the imbalance force calculated at 206. For example, the pressure magnitude at each selected frequencies may be assigned with a first weighting factor, and the imbalance force may be assigned with a second weighting factor. The cost function may be the sum of the pressure magnitudes multiplied with the first weighting factor and the imbalance force multiplied with the second weighting factor. In another embodiment, the pressure magnitude at each selected frequencies may be assigned with different weighting factors. The weighting factors may be determined based on the sensitivity of the human ear at the particular frequency. The calculated cost function, pressure magnitude at the selected frequencies, and imbalance force may be saved in the screening DOE table.

At 212, the method determines if the most recently generated blade arrangement is the optimal arrangement. In one example, method 200 may determine that the arrangement is optimal if 1) the difference between the recently generated arrangement and the previous arrangement is less than a threshold; and 2) the cost function calculated at 210 is less than a threshold. In other words, method 200 may stop the optimization process if a local minimum has been reached. If the optimal blade arrangement is found, method moves to 216 to output the optimal blade arrangement. Otherwise, method 200 moves to 214.

At 214, the design optimization table is generated based on the DOE exploration In one example, generating the design optimization table may include generating a new blade arrangement, or the size and sequence of blade spacings between adjacent blades around the hub, is bounded by Condition 1 and Condition 2 defined at 204. The new blade arrangement may be generated via genetic algorithm of multi-objective optimization. After the new blade arrangement is generated, method 200 moves on to 208 to calculate the pressure and imbalance force of the newly generated blade arrangement.

FIG. 3 shows example results of the optimization process for a six-blade fan. Each grey-scaled dot on the graph indicates a blade arrangement within the DOE table. For each blade arrangement, the imbalance force, the pressure magnitude at the third harmonic, the fourth harmonic, and the fifth harmonic frequencies are illustrated. Reduced imbalance force and reduced pressure magnitude result in reduced NVH. The x-axis indicates the imbalance force, and arrow 302 indicates reduced NVH. The y-axis indicates pressure magnitude at the third harmonic frequency, and arrow 301 indicates reduced NVH. The pressure magnitude at the fourth harmonic is indicated by the grey scales. The pressure magnitude at the fifth harmonic is indicated by the size of the dot. Without optimization, the blade arrangement 303 of the fan with non-optimized spacings can generated high NVH at the fundamental, the third harmonic, the fourth harmonic, and the fifth harmonic frequencies. Through optimization, NVH of blade arrangement 304 of the fan may be reduced by decreased imbalance force, and decreased pressure magnitude across the selected frequencies, especially in the third harmonic frequency.

FIGS. 4A-4B, 5A-5B, 6A-6B, and 7A-7B show optimized arrangements of blade spacings for a fan with six, seven, eight, and nine blades. Each fan includes a hub at the center. The blades are arranged circumferentially around the hub. The fan may be rotated around the central axis of the hub to increase air flow. The blades are identical, and are coupled to the hub in the same way. For example, the blades have the same size, shape, and pitch. Each blade includes a leading edge indicated by the dashed lines. Each two of adjacent blades are separated by a spacing. For example, in FIG. 4A, adjacent blades 411 and 412 are separated by spacing 440. In one embodiment, the spacing between adjacent blades may be defined by the radial angle between the adjacent leading edges. For example, in FIG. 4A, the spacing between adjacent blades 411 and 412 is the radial angle 440 of between the leading edge 430 of blade 411 and the leading edge 431 of blade 412. Blade 411 and blade 412 are arranged adjacent to each other, with no other blade in between. In another embodiment, the spacing may be defined by the radial angle between the central axes of the blades. The spacing may be selected from one of the small blade spacing S, the medium blade spacing M, and the large blade spacing L. The range of each blade spacing is defined in Condition 1 at step 204 of FIG. 2. As such, circumferentially and clockwise around the hub, the blade spacings may be arranged in a combination or sequence of the small blade spacing, the medium blade spacing, and the large blade spacing. For example, in FIG. 4A, the sequence of blade spacing of the fan is MLSSM without any other spacings therebetween L, which corresponds to spacings in the sequence of 440, 441, 442, 443, 444, 445.

FIGS. 4A-4B show two examples of six-blade fan with spacings selected from the small blade spacing, the medium blade spacing, and the large blade spacing. The small blade spacing S is in the range of

$\frac{360}{6}-\delta \le S\le \frac{360}{6}+\frac{\delta }{2},$

the medium spacing M is in the range of

$\frac{360}{6}-\frac{\delta }{2}<M<\frac{360}{6}+\frac{\delta }{2},$

and the large spacing L is in the range of

$\frac{360}{6}+\frac{\delta }{2}\le L\le \frac{360}{6}+\delta ,$

wherein δ ∈ (0,10]. Both examples include two small blade spacings, two medium blade spacings, and two large blade spacings, wherein the medium blade spacing is smaller than the large blade spacing and larger than the small blade spacing.

In FIG. 4A, blades 411, 412, 413, 414, 415, and 416 are arranged circumferentially around hub 410. Blades 411 are 412 are separated by spacing 440. Blades 412 and 413 are separated by spacing 441. Blades 413 and 414 are separated by spacing 442. Blades 414 and 415 are separated by spacing 443. Blades 415 and 416 are separated by spacing 444. Blades 416 and 411 are separated by spacing 445. Spacings 442 and 443 are small blade spacing S, and are adjacent to each other. Spacings 440 and 444 are medium spacings M. Spacings 445 and 441 are large spacings L. As such, the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of MLSSML circumferentially around the hub without any other spacings therebetween. In one example, the size of the blade spacing between adjacent blades around the hub are 56.5°, 68.6°, 50°, 54.9°, 60°, and 70°.

In FIG. 4B, blades 421, 422, 423, 424, 425, and 426 are arranged circumferentially around hub 420. Blades 421 are 422 are separated by spacing 451. Blades 422 and 423 are separated by spacing 452. Blades 423 and 424 are separated by spacing 453. Blades 424 and 425 are separated by spacing 454. Blades 425 and 426 are separated by spacing 456. Blades 426 and 421 are separated by spacing 456. Spacings 456 and 453 are small spacing S. Spacings 451 and 454 are medium spacing M. Spacings 452 and 455 are large spacing L. As such, the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of MLSMLS circumferentially around the hub 420. The two small blade spacings are opposite to each other relative to the hub 420. The two medium blade spacings are opposite to each other relative to the hub 420. The two large blade spacings are opposite to each other relative to the hub 420.

FIGS. 5A-5B show two examples of seven-blade fan with spacings selected from the small blade spacing, the medium blade spacing, and the large blade spacing. The spacings include one medium blade spacing, at least two small blade spacings adjacent to each other, and at least two large blade spacings. The small blade spacing S is in the range of

$\frac{360}{7}-\delta \le S\le \frac{360}{7}+\frac{\delta }{2},$

the medium spacing M is in the range of

$\frac{360}{7}-\frac{\delta }{2}<M<\frac{360}{7}+\frac{\delta }{2},$

and the large spacing L is in the range of

$\frac{360}{7}+\frac{\delta }{2}\le L\le \frac{360}{7}+\delta ,$

wherein δ ∈ (0,10].

In FIG. 5A, blades 511, 512, 513, 514, 515, 516, and 517 are arranged circumferentially around hub 510. Blades 511 are 512 are separated by spacing 531. Blades 512 and 513 are separated by spacing 532. Blades 513 and 514 are separated by spacing 533. Blades 514 and 515 are separated by spacing 534. Blades 515 and 516 are separated by spacing 535. Blades 516 and 517 are separated by spacing 536. Blade 517 and 511 are separated by spacing 537. Spacings 531, 532, and 535 are small spacing S. Spacings 534 is medium spacing M. Spacings 533, 536, and 537 are large spacing L. As such, the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SSLMSLL circumferentially around the hub without any other spacings therebetween. In one example, the size of the blade spacing between adjacent blades around the hub are 42.3°, 44.1°, 58.8°, 55.6°, 41.4°, 56.4°, and 61.4°.

In FIG. 5B, blades 521, 522, 523, 524, 525, 526, and 527 are arranged circumferentially around hub 520. Blades 521 are 522 are separated by spacing 541. Blades 522 and 523 are separated by spacing 542. Blades 523 and 524 are separated by spacing 543. Blades 524 and 525 are separated by spacing 544. Blades 525 and 526 are separated by spacing 545. Blades 526 and 527 are separated by spacing 546. Blade 527 and 521 are separated by spacing 547. Spacings 541, 542, 545, and 546 are small spacing S. Spacings 544 is medium spacing M. Spacings 543, and 547 are large spacing L. As such, the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SSLMSSL circumferentially around the hub without any other spacings therebetween.

FIGS. 6A-6B shows two examples of eight-blade fan with spacing selected from the small blade spacing, the medium blade spacing, and the large blade spacing. The small blade spacing S is in the range of

$\frac{360}{8}-\delta \le S\le \frac{360}{8}+\frac{\delta }{2},$

the medium blade spacing M is in the range of

$\frac{360}{8}-0.8\frac{{\delta }_{\min }}{2}<M<\frac{360}{7}+0.8\frac{{\delta }_{\max }}{2},$

and the large spacing L is in the range of

$\frac{360}{8}+\frac{\delta }{2}\le L\le \frac{360}{8}+\delta ,\delta \in \left(0,10\right].$

The spacings include a plurality of small blade spacings S and a plurality of large blade spacings L arranged in the sequence of LLSSL circumferentially around the hub without any other spacings therebetween.

In FIG. 6A, blades 611, 612, 613, 614, 615, 616, 617, and 618 are arranged circumferentially around hub 610. Blades 611 are 612 are separated by spacing 631. Blades 612 and 613 are separated by spacing 632. Blades 613 and 614 are separated by spacing 633. Blades 614 and 615 are separated by spacing 634. Blades 615 and 616 are separated by spacing 635. Blades 616 and 617 are separated by spacing 636. Blade 617 and 618 are separated by spacing 637. Blade 618 and 611 are separated by spacing 638. Spacings 631, 635, and 636 are small spacing S. Spacings 632 and 638 are medium spacing M. Spacings 633, 634, and 637 are large spacing L. As such, the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SMLLSSLM circumferentially around the hub without any other spacings therebetween. In one example, the size of the blade spacing between adjacent blades around the hub are 35°, 43.6°, 50°, 55°, 37.7°, 35°, 55°, and 48.7°.

In FIG. 6B, blades 621, 622, 623, 624, 625, 626, 627, and 628 are arranged circumferentially around hub 620. Blades 621 are 622 are separated by spacing 641. Blades 622 and 623 are separated by spacing 642. Blades 623 and 624 are separated by spacing 643. Blades 624 and 625 are separated by spacing 644. Blades 625 and 626 are separated by spacing 645. Blades 626 and 627 are separated by spacing 646. Blade 627 and 628 are separated by spacing 647. Blade 628 and blade 621 are separated by spacing 648. Spacings 642, 643, 646, and 647 are small spacing S. Spacings 641, 644, 645, and 648 are large spacing L. As such, the small blade spacing and the large blade spacing are arranged in a sequence of LSSLLSSL circumferentially around the hub without any other spacings therebetween.

FIGS. 7A-7C show three examples of nine-blade fan with spacing selected from the small blade spacing, the medium blade spacing, and the large blade spacing. The small blade spacing S is in the range of

$\frac{360}{9}-\delta \le S\le \frac{360}{9}+\frac{\delta }{2},$

the medium blade spacing M is in the range of

$\frac{360}{9}-0.2\frac{\delta }{2}<M<\frac{360}{9}+0.2\frac{\delta }{2},$

and the large spacing L is in the range of

$\frac{360}{9}+\frac{\delta }{2}\le L\le \frac{360}{9}+\delta ,\delta \in \left(0,10\right].$

In one example, the optimized spacings include a plurality of small blade spacings S and a plurality of large blade spacings L arranged in a sequence of LLSS circumferentially around the hub without any other spacings therebetween. In another example, the optimized spacing include one medium spacing.

In an example fan of FIG. 7A, blades 711-719 are arranged circumferentially clockwise around hub 710. The adjacent blades are separated by spacings 741-749. Spacings 741, 742, 743, 746, and 747 are small spacings S. Spacing 715 is medium spacing M. Spacings 744, 748, and 749 are large spacing L. As such, the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SSSLMSSLL clockwise around the hub without any other spacings therebetween. In one example, the size of the blade spacing between adjacent blades around the hub are 35°, 35°, 35°, 50°, 40°, 35°, 35°, 45°, and 50°.

In an example fan of FIG. 7B, blades 721-729 are arranged circumferentially clockwise around hub 720. The adjacent blades are separated by spacings 751-759. Spacings 753, 754, 758, and 759 are small spacings S. Spacing 755 is medium spacing M. Spacings 751, 752, 756, and 757 are large spacing L. As such, the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of LLSSMLLSS clockwise around the hub without any other spacings therebetween.

In an example fan of FIG. 7C, blades 731-739 are arranged circumferentially clockwise around hub 730. The adjacent blades are separated by spacings 761-769. Spacings 762, 763, 767, and 768 are small spacings S. Spacing 765 is medium spacing M. Spacings 761, 764, 766, and 769 are large spacing L. As such, the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of LSSLMLSSL clockwise around the hub without any other spacings therebetween.

In this way, by optimizing the spacing of blades of a fan, the NVH generated by the fan due to imbalance force as well as pressure generated at selected harmonics may be reduced. The technical effect of minimizing the pressure magnitude at selected harmonics is that noises that cannot covered by engine noise may be reduced. The technical effect of minimizing the imbalance force is that NVH due to asymmetric arrangement of blade spacing may be reduced. The technical effect of selecting the spacing between adjacent blades from the small, medium, and large spacing is that the process of assembling the fan may be simplified.

As one embodiment, a fan comprises a hub; and six blades disposed circumferentially around the hub with uneven spacings between adjacent blades, the spacings include two small blade spacings, two medium blade spacings, and two large blade spacings, wherein the medium blade spacing smaller than the large blade spacing and larger than the small blade spacing. In a first example of the fan, the small blade spacing S is in a range of

$\frac{360}{6}-\delta \le S\le \frac{360}{6}+\frac{\delta }{2},$

the medium spacing M is in a range of

$\frac{360}{6}-\frac{\delta }{2}<M<\frac{360}{6}+\frac{\delta }{2},$

and the large spacing L is in a range of

$\frac{360}{6}+\frac{\delta }{2}\le L\le \frac{360}{6}+\delta ,$

wherein δ ∈ (0,10]. A second example of the fan optionally includes the first example and further includes wherein the two small blade spacings are adjacent to each other. A third example of the fan optionally includes one or more of the first and second examples, and further includes wherein the small blade spacing S, the medium blade spacing M, and the large blade spacing L are arranged in a sequence of MLSSML circumferentially around the hub without any other spacings therebetween. A fourth example of the fan optionally includes one or more of the first through third examples, and further includes, where in the two small blade spacings are opposite to each other relative to the hub, the two medium blade spacings are opposite to each other relative to the hub, and the two large blade spacings are opposite to each other relative to the hub. A fifth example of the fan optionally includes one or more of the first through fourth examples, and further includes, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of MLSMLS circumferentially around the hub without any other spacings therebetween.

As another embodiment, a fan comprises a hub; and seven blades disposed circumferentially around the hub with uneven spacings between adjacent blades, wherein the spacings include one medium blade spacing, at least two small blade spacings adjacent to each other, and at least two large blade spacings. In a first example of the fan, the small blade spacing S is in a range of

$\frac{360}{7}-\delta \le S\le \frac{360}{7}+\frac{\delta }{2},$

the medium spacing M is in a range of

$\frac{360}{7}-\frac{\delta }{2}<M<\frac{360}{7}+\frac{\delta }{2},$

and the large spacing L is in a range of

$\frac{360}{7}+\frac{\delta }{2}\le L\le \frac{360}{7}+\delta ,$

wherein δ ∈ (0,10]. A second example of the fan optionally includes the first example and further includes, wherein the small blade spacing S, the medium blade spacing M, and the large blade spacing L are arranged in a sequence of SSLMSLL circumferentially around the hub without any other spacings therebetween. A third example of the fan optionally includes one or more of the first and second examples, and further includes, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SSLMSSL circumferentially around the hub without any other spacings therebetween.

As another embodiment, a fan comprises a hub; and eight blades disposed circumferentially around the hub with uneven spacings between adjacent blades, wherein the spacings include a plurality of small blade spacings S and a plurality of large blade spacings L arranged in the sequence of LLSSL circumferentially around the hub without any other spacings therebetween. In a first example of the fan, the small blade spacing S is in a range of

$\frac{360}{8}-\delta \le S\le \frac{360}{8}+\frac{\delta }{2},$

and the large spacing L is in a range of

$\frac{360}{8}+\frac{\delta }{2}\le L\le \frac{360}{8}+\delta ,$

wherein δ ∈ (0,10]. A second example of the fan optionally includes the first example and further includes, a medium blade spacing, the medium blade spacing smaller than the large blade spacing and larger than the small blade spacing, the medium spacing M is in a range of

$\frac{360}{8}-0.8\frac{\delta }{2}<M<\frac{360}{7}+0.8\frac{\delta }{2}.$

A third example of the fan optionally includes one or more of the first and second examples, and further includes, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SMLLSSLM circumferentially around the hub without any other spacings therebetween. A fourth example of the fan optionally includes one or more of the first through third examples, and further includes, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of LSSLLSSL circumferentially around the hub without any other spacings therebetween.

As another embodiment, a fan comprises a hub; and nine blades disposed circumferentially around the hub with uneven spacings between adjacent blades, wherein the spacings include a plurality of small blade spacings S and a plurality of large blade spacings L arranged in a sequence of LLSS circumferentially around the hub. In a first example of the fan, the fan further include one medium spacing M, the medium blade spacing smaller than the large blade spacing and larger than the small blade spacing, the medium spacing is in a range of

$\frac{360}{9}0.2\frac{\delta }{2}<M<\frac{360}{9}+0.2\frac{\delta }{2},$

wherein δ ∈ (0,10] . A second example of the fan optionally includes the first example and further includes, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SSSLMSSLL circumferentially around the hub without any other spacings therebetween. A third example of the fan optionally includes one or more of the first and second examples, and further includes, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of LLSSMLLSS circumferentially around the hub without any other spacings therebetween. A fourth example of the fan optionally includes one or more of the first through third examples, and further includes, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of LSSLMLSSL circumferentially around the hub without any other spacings therebetween.

In another representation, the fan may be a cooling fan installed in a hybrid vehicle.

Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the engine control system, where the described actions are carried out by executing the instructions in a system including the various engine hardware components in combination with the electronic controller.

It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.

Claims

1. A fan, comprising:

a hub; and

six blades disposed circumferentially around the hub with uneven spacings between adjacent blades, the spacings include two small blade spacings, two medium blade spacings, and two large blade spacings, wherein the medium blade spacing is smaller than the large blade spacing and larger than the small blade spacing.

2. The fan of claim 1, wherein the small blade spacing S is in a range of 360 6 - δ ≤ S ≤ 360 6 + δ 2, the medium spacing M is in a range of 360 6 - δ 2 < M < 360 6 + δ 2, and the large spacing L is in a range of 360 6 + δ 2 ≤ L ≤ 360 6 + δ, wherein δ ∈(0,10].

3. The fan of claim 1, wherein the two small blade spacings are adjacent to each other.

4. The fan of claim 3, wherein the small blade spacing S, the medium blade spacing M, and the large blade spacing L are arranged in a sequence of MLSSML circumferentially around the hub without any other spacings therebetween.

5. The fan of claim 1, wherein the two small blade spacings are opposite to each other relative to the hub, the two medium blade spacings are opposite to each other relative to the hub, and the two large blade spacings are opposite to each other relative to the hub.

6. The fan of claim 5, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of MLSMLS circumferentially around the hub without any other spacings therebetween.

7. A fan, comprising:

a hub; and

seven blades disposed circumferentially around the hub with uneven spacings between adjacent blades, wherein the spacings include one medium blade spacing, at least two small blade spacings adjacent to each other, and at least two large blade spacings.

8. The fan of claim 7, wherein the small blade spacing S is in a range of 360 7 - δ ≤ S ≤ 360 7 + δ 2, the medium spacing M is in a range of 360 7 - δ 2 < M < 360 7 + δ 2, and the large spacing L is in a range of 360 7 + δ 2 ≤ L ≤ 360 7 + δ, wherein δ ∈ (0,10].

9. The fan of claim 7, wherein the small blade spacing S, the medium blade spacing M, and the large blade spacing L are arranged in a sequence of SSLMSLL circumferentially around the hub without any other spacings therebetween.

10. The fan of claim 7, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SSLMSSL circumferentially around the hub without any other spacings therebetween.

11. A fan, comprising:

a hub; and

eight blades disposed circumferentially around the hub with uneven spacings between adjacent blades, wherein the spacings include a plurality of small blade spacings S and a plurality of large blade spacings L arranged in the sequence of LLSSL circumferentially around the hub without any other spacings therebetween.

12. The fan of claim 11, wherein the small blade spacing S is in a range of 360 8 - δ ≤ S ≤ 360 8 + δ 2, and the large spacing L is in a range of 360 8 + δ 2 ≤ L ≤ 360 8 + δ, wherein δ ∈ (0,10].

13. The fan of claim 12, further includes a medium blade spacing, the medium blade spacing smaller than the large blade spacing and larger than the small blade spacing, the medium spacing M is in a range of 360 8 - 0.8  δ 2 < M < 360 7 + 0.8  δ 2.

14. The fan of claim 13, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SMLLSSLM circumferentially around the hub without any other spacings therebetween.

15. The fan of claim 11, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of LSSLLSSL circumferentially around the hub without any other spacings therebetween.

16. A fan, comprising:

a hub; and

nine blades disposed circumferentially around the hub with uneven spacings between adjacent blades, wherein the spacings include a plurality of small blade spacings S and a plurality of large blade spacings L arranged in a sequence of LLSS circumferentially around the hub without any other spacings therebetween.

17. The fan of claim 16, further include one medium spacing M, the medium blade spacing smaller than the large blade spacing and larger than the small blade spacing, the medium spacing is in a range of 360 9 - 0.2  δ 2 < M < 360 9 + 0.2  δ 2, wherein δ ∈ (0,10].

18. The fan of claim 16, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of SSSLMSSLL circumferentially around the hub without any other spacings therebetween.

19. The fan of claim 16, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of LLSSMLLSS circumferentially around the hub without any other spacings therebetween.

20. The fan of claim 16, wherein the small blade spacing, the medium blade spacing, and the large blade spacing are arranged in a sequence of LSSLMLSSL circumferentially around the hub without any other spacings therebetween.