Fan for a motor vehicle with a fan wheel mounted on a horizontal axis and a fan module comprising such a fan

Abstract

Fan (105) for a motor vehicle (110), the fan (105) comprising the following elements: - a fan wheel (125) which is mounted for rotation about a horizontal axis of rotation (120); - a fan belt (205) arranged radially outwardly on the fan wheel (125); - a housing (130) for receiving the fan wheel (125); - wherein a sealing geometry (210) extends radially inward from the housing (130) to form an axial gap seal with a gap (135) with the fan band (205), characterized in that on the stationary fan (105) the gap (135) between the fan band (205) and the sealing geometry (210) is maximum in a vertical direction, wherein the gap (135) is larger in an upper (12 o'clock position) and lower area (6 o'clock position) than in a left (3 o'clock position) and right area (9 o'clock position).

Description

[0001] The invention relates to a fan and a fan module. In particular, the invention relates to a fan and a fan module for generating an air flow in a motor vehicle. State of the art

[0002] In a motor vehicle, a fan is used to generate an airflow that, for example, dissipates heat from a heat exchanger. In particular, the motor vehicle can be driven by an internal combustion engine, with the heat generated by the internal combustion engine being transferred to a fluid flowing through the heat exchanger. In various embodiments, the fan can be arranged upstream or downstream of the heat exchanger.

[0003] Such a fan typically comprises a fan impeller mounted to rotate about a horizontal axis of rotation. A housing is provided around the outer circumference of the fan impeller to seal the fan impeller from the environment and to guide the conveyed air. Regardless of whether the fan is an axial or radial fan, there is an axial and / or radial gap seal between the housing and the fan impeller. Air flowing past the fan impeller through the gap seal is not accelerated by the fan and therefore does not leak. To ensure a sufficient volume flow of the conveyed air, efforts are made to keep the gap as small as possible to limit leakage losses. However, this increases the risk of collision between an outer region of the fan impeller and the housing in the area of the gap.

[0004] The fan impeller has only a finite stiffness, so it can deform axially during operation. Deformation can be caused, for example, by the movement of the vehicle while driving. Therefore, the gap is usually dimensioned to minimize collision even under unfavorable conditions, and the resulting leakage losses are accepted.

[0005] The invention is based on the object of providing a fan and a fan module in which leakage losses are minimized as much as possible, so that the efficiency of the fan is maximized as much as possible without causing a collision between an outer region of the fan wheel and the housing. The invention achieves this object by means of a fan and a fan module having the features of the independent claims. Subclaims specify preferred embodiments.

[0006] WO 2008 / 074307 A1, DE 198 57 926 A1 and DE 10 2008 041 078 A1 all disclose the optimization of an axial fan with a radially outer annular gap. Disclosure of the invention

[0007] A fan for a motor vehicle according to the invention comprises a fan wheel mounted for rotation about a horizontal axis of rotation, a fan band arranged radially outward on the fan wheel, and a housing for accommodating the fan wheel. A sealing geometry extends radially inward from the housing to form an axial gap seal with the fan band. The gap between the fan band and the sealing geometry is maximal in a vertical direction when the fan is stationary.

[0008] If the stationary fan wheel rotates around its vertical axis, for example, when the vehicle is cornering, forces act on the fan wheel that reduce the gap between the fan band and the sealing geometry in a horizontal direction. Starting with a uniform gap dimension across the circumference when stationary, the smallest gap dimension when the fan wheel is stationary and rotating around its vertical axis is found in a plane around the axis of rotation, i.e., in a right or left area of the fan wheel.

[0009] However, it was recognized that the situation is fundamentally different when the fan impeller is rotating. Due to the precession effect of the fan impeller acting as a gyroscope, the forces acting around the vertical axis only take effect 90° later around the axis of rotation. When the fan impeller is rotating and the fan is simultaneously pivoted around the vertical axis, the smallest gap between the sealing geometry and the fan band is therefore in a vertical direction. The fan impeller or fan band will therefore collide with the housing or sealing geometry at the top or bottom. By providing an increased distance between the fan band and the sealing geometry in the upper or lower area, the risk of collision can be counteracted without increasing the gap over the entire circumference of the fan impeller or sealing geometry. This can result in collision-free operation of the fan impeller in the housing while simultaneously minimizing leakage losses.The airflow through the fan can thus be maximized, which can also improve the efficiency of the fan.

[0010] According to the invention, the gap is larger in an upper or lower area than in a left or right area of the housing. The gap is enlarged in both the upper and lower areas to accommodate, for example, cornering in both directions and when the motor vehicle is moving forward or backward.

[0011] In one embodiment, the gap is varied by axially shifting regions of the sealing geometry around the circumference. The fan impeller can thus remain unchanged. The changes to the housing or sealing geometry can be easily implemented. Furthermore, an already established, aerodynamically advantageous sealing geometry design can be maintained over the entire circumference, while only the position of sections of the sealing geometry is shifted.

[0012] The fan band can extend radially outward and counter to the flow direction of the conveyed air, while the sealing geometry extends radially inward and in the flow direction. This allows a good sealing effect of the gap seal to be achieved without complicating assembly of the fan impeller in the housing. In particular, a one-piece housing can be used, into which the fan impeller is inserted axially during assembly. In other embodiments, the gap seal can also be designed in several stages, so that it can be referred to as a labyrinth seal. In this case, the invention can preferably be applied to all of the resulting axial gaps.

[0013] The gap can be dimensioned in a vertical direction depending on the maximum rotational speed of the fan around the vertical axis in such a way that a collision between the fan band and the sealing geometry is prevented. The dimensioning can also depend on the maximum rotational speed of the fan. The maximum axial deflection of the fan band due to the rotation of the fan around the vertical axis can be determined mathematically or empirically on the basis of the maximum rotational speed of the fan, if applicable the maximum rotational speed around the vertical axis, the stiffness of the fan impeller or the housing. The gap should therefore preferably be dimensioned in such a way that the specific deflection is possible in the upper or lower area of the sealing geometry without a collision of the fan band having to be expected.Sections of the sealing geometry that lie within a horizontal plane through the rotation axis do not need to be modified. The transition between the modified and unchanged areas should preferably be smooth or continuous to avoid flow losses at abrupt transitions.

[0014] In a particularly preferred embodiment, the fan is an axial fan. This design is particularly preferred for use in heat exchangers due to its low overall height.

[0015] The fan can be installed upstream of a heat exchanger, so that the air flows first through the fan and then through the heat exchanger, or downstream, so that the air flows first through the heat exchanger and then through the fan.

[0016] If the fan is located downstream of a heat exchanger, it is referred to as an intake fan. In the opposite arrangement, if the fan is located upstream of a heat exchanger, it is referred to as a pressure fan. The invention can be used in both variants.

[0017] The fan wheel can be located upstream or downstream of a drive, which can be designed as an electric motor, particularly a hub motor. Here, too, the invention can be used in both variants.

[0018] Experience has shown that the problem of the fan belt colliding with the sealing geometry occurs more frequently in suction fans with a fan located downstream of the heat exchanger. The following example describes a suction fan with a fan wheel located downstream of the drive. The drive can be implemented as an electric motor, particularly a hub motor.

[0019] A fan module according to the invention comprises the described fan, a hub motor for driving the fan wheel, and a strut for supporting the hub motor on the housing. When dimensioning the gap, the elasticity of the strut or the hub motor can be taken into account, which can influence the maximum axial deflection and thus the minimum gap width. The fan module can thus also have a gap at the gap seal that is optimized in this regard.

[0020] The invention will now be described in detail with reference to the accompanying figures, in which: Fig. 1 a fan module in a motor vehicle; Fig. 2 the fan module from Fig. 1 in different views; and Fig. 3 a half-section through the fan module of the Fig. 1 and Fig. 2 represents. Detailed description of implementation examples

[0021] Fig. 1 shows a fan module 100 with a fan 105 on a motor vehicle 110. Relative to a normal direction of travel of the motor vehicle 110, the fan module 100 is preferably mounted at the front and configured to create an air flow opposite to the direction of travel through a heat exchanger 115 located directly in front of the fan module 100. Here, the fan module 100 is located downstream, but in other embodiments it can also be mounted upstream of the heat exchanger 115. Both elements can also be mounted at a different location on the motor vehicle 110, for example, at the rear. The direction of the created air flow can also be different, for example, transverse to the normal direction of travel. The fan 105 shown is an axial fan that creates an air flow in a horizontal plane, although a radial fan that creates an air flow in a vertical plane can also be used.In any case, the axis of rotation of the fan 100 lies in the horizontal plane.

[0022] An axis of rotation 120, about which a fan wheel 125 of the fan 105 is rotatable, lies, for example, in a horizontal plane. Preferably, a housing 130 is provided, which is separated from the fan wheel 125 by an axial gap 135. In another embodiment, the axial gap 135 can also arise between the fan wheel 125 and another surrounding component. To reference individual sections of the gap 135, a clock face notation is used below, in which the housing 130 is conceptually replaced by a clock face with the 12 o'clock position vertically at the top.

[0023] If the switched-off fan 105 is rotated about the vertical axis 140, for example because the motor vehicle 110 is negotiating a curve, the mass inertia and elasticity of the fan wheel 125, the hub motor 215, and the housing 130 cause the axial gap 135 to decrease in the 3 o'clock position or the 9 o'clock position, depending on the direction of the curve. However, this only applies when the fan wheel 125 is stationary. If the fan wheel 125 rotates about the rotational axis 120, the forces acting about the vertical axis 140, relative to the rotational axis 120, only act on the fan wheel 125, the hub motor 215, and the housing 130 90° later. The axial gap 135 will therefore be minimal in the 12 o'clock position or the 6 o'clock position, unlike before. Since the collision between the fan wheel 125 and the housing can generally lead to greater damage during fan operation than when the fan wheel is stationary, the collision should be prevented in particular when the fan wheel is rotating.

[0024] The extent to which the gap 135 is enlarged or reduced is primarily determined by the rigidity of the fan wheel 125, the hub motor 215, and the housing 130, a maximum rotational speed of the fan 105, and a maximum rotational rate of the motor vehicle 110 surrounding the fan module 100 about the vertical axis 140. The maximum rotational rate of the motor vehicle 110 about the vertical axis 140 can be at a relatively low driving speed, for example, in a range of approximately 5 to 20 km / h, for example, when the motor vehicle 110 is maneuvered or turned.

[0025] It is proposed to increase the width of the gap 135 in a vertical direction, i.e. in the region of the 12 o'clock position and / or the 6 o'clock position, in order to reduce the risk of collision between the fan wheel 125 and the housing 130 when the fan 105 rotates about the vertical axis 140.

[0026] Fig. 2 shows the fan module 100 of Fig. 1 in three different views. In an upper section, a perspective view of the side facing away from the direction of travel is shown, in a middle section, a top view of the side facing away from the direction of travel, and in a lower section, a top view of the side facing in the direction of travel of the fan module 100. The central component of the fan module 100 is a fan 105, which comprises the fan wheel 125, a fan band 205 arranged radially on the outside of the fan wheel 125, the housing 130, and a sealing geometry 210 on the housing 130. An axial gap 135 exists between the fan band 205 and the sealing geometry 210. The gap 135 is an annular gap, and the fan band 205, together with the sealing geometry 210, forms a gap seal, which is also referred to as a labyrinth seal.

[0027] In addition to the fan 105, the fan module 100 also comprises a hub motor 215 for driving and rotatably supporting the fan wheel 125 about the rotation axis 120, as well as a strut 220 for supporting the hub motor 215 on the housing 130. In the illustrated embodiment, an electrical plug connection 225 is also provided for providing an electrical connection of the hub motor 215. The installation position of the illustrated fan module 100, based on the illustration of Fig. 1, is exemplary such that the connector 225 is arranged at the top left against the direction of travel.

[0028] Fig. 3 shows a half section through the fan module 100 of the Fig. 1 and Fig. 2. In the illustrated embodiment, the fan band 205 extends radially outward from a radially outer region of the fan impeller 125 and at the same time counter to a flow direction 305 of air conveyed by the fan 105. The sealing geometry 210 corresponding to the fan band 205 extends radially inward from the housing 130 and in the direction of the flow direction 305. The fan band 205 and the sealing geometry 210 thus form an axial gap 135 that acts as a gap seal between the fan impeller 125 and the housing 130. A leakage flow 310 runs through the gap 135, is deflected at least twice in the region of the gap seal and passes through the gap 135 in between. The greater the flow resistance of the gap seal, the lower the mass flow of air through the gap seal.

[0029] Through the leakage flow 310, part of the air passes from the Fig. 3 lower area of the fan wheel 125 to its upper area, without this part of the air being accelerated by the fan wheel 125. The larger the leakage flow 310, the lower the mass flow conveyed by the fan 105 can be. If the mass flow drops below a predetermined threshold, a cooling effect of the conveyed air, for example on the heat exchanger 115 in Fig. 1, may no longer be sufficient. As a result, the heat exchanger 115 can no longer adequately perform its function, so that, for example, an internal combustion engine cooled by the heat exchanger 115 may have an increased operating temperature, which can lead to reduced power output and increased wear.

[0030] In order to minimize the leakage flow 310, it is generally attempted to select the gap 135 as small as possible without risking a collision between the fan wheel 125 or the fan band 205 and the housing 130 or the sealing geometry 210. In Fig. 3, the width of the gap 135 is shown as gap dimension 315 or 320 in the axial direction.

[0031] As already explained above, it is proposed to vary the axial width of the gap 135 over its circumference around the axis of rotation 120. For example, a smaller gap dimension 315 can be used in an area around the 3 o'clock position and / or the 9 o'clock position, while a larger gap dimension 320 is used in an area around the 12 o'clock position or the 6 o'clock position. In a preferred embodiment, the gap dimensions at sections of the housing 130 opposite one another with respect to the axis of rotation 120 are always the same. The gap dimension can be varied, in particular, by displacing the sealing geometry 210 on the housing 130 in the axial direction with respect to the axis of rotation 120. The dashed line shows a section of the housing 130 corresponding to the larger gap dimension 320, wherein this section is offset axially opposite to the flow direction 305 compared to the section with the solid line corresponding to the smaller gap dimension 315.

Claims

[1] Fan (105) for a motor vehicle (110), the fan (105) comprising the following elements: - a fan wheel (125) which is mounted for rotation about a horizontal axis of rotation (120); - a fan belt (205) arranged radially outwardly on the fan wheel (125); - a housing (130) for receiving the fan wheel (125); - wherein a sealing geometry (210) extends radially inward from the housing (130) to form an axial gap seal with a gap (135) with the fan band (205), characterized by , that on the stationary fan (105) the gap (135) between the fan band (205) and the sealing geometry (210) is maximum in a vertical direction, wherein the gap (135) is larger in an upper (12 o'clock position) and lower area (6 o'clock position) than in a left (3 o'clock position) and right area (9 o'clock position). [2] Fan (105) according to claim 1, wherein the gap (135) is varied by axially displacing regions of the sealing geometry (210) over the circumference. [3] Fan (105) according to one of the preceding claims, wherein the fan band (205) extends radially outwards and counter to the flow direction (305) of the conveyed air, while the sealing geometry (210) extends radially inwards and in the flow direction (305). [4] Fan (105) according to one of the preceding claims, wherein the gap (135) is dimensioned in a vertical direction as a function of a maximum rotational speed of the fan (105) about a vertical axis (140) such that a collision between the fan band (205) and the sealing geometry (210) is prevented. [5] Fan (105) according to one of the preceding claims, wherein the fan (105) is an axial fan. [6] Fan (105) according to one of the preceding claims, wherein the fan (105) is arranged for use downstream of a heat exchanger (115). [7] Fan module comprising a fan (105) according to one of the preceding claims, a hub motor (215) for driving the fan wheel (125) and a strut (220) for supporting the hub motor on the housing (130).

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