Method for reducing body vibrations by means of the electric motor of an electric vehicle

Abstract

In various embodiments, a method is provided for reducing vibration of the vehicle body (1) by means of a motor (4) of an electric vehicle, the method comprising: determining vibration of a subframe (2) or vibration of the vehicle body (1) in a region of force introduction via the subframe (2), wherein the motor (4) is supported on the vehicle body (1) or the subframe (2); determining the torque required by the motor (4) to introduce a force into the subframe (2) or the vehicle body (1), the force counteracting the force caused by the determined vibration and acting on the subframe (2) or the vehicle body (1); and adjusting at least one drive signal of the motor (4) based on a change in the drive torque of the motor (4) to generate the desired torque. An electric vehicle configured to perform the method according to the invention is also provided.

Description

Technical Field

[0001] This invention relates to a method for reducing vehicle body vibration by means of an electric motor in an electric vehicle. Background Technology

[0002] For vehicles with internal combustion engines and those with electric motors, the noise level in the passenger compartment during operation is an important quality standard. This is especially true for luxury vehicles, where passengers are accustomed to experiencing virtually no external noise (such as noise from passing vehicles) or that all perceived external noise is significantly attenuated. During vehicle sound tuning, particular attention should be paid to minimizing the amount of noise generated by the vehicle itself during operation (such as airborne or engine noise) that enters the passenger compartment.

[0003] Besides airborne noise, a permanent driving noise associated with moving vehicles is caused by the contact between the tires and the road surface. Due to road surface vibrations, particularly those caused by potholes, bumps, and small defects, the vehicle tires and associated axles are stimulated by these vibrations, which introduce forces into the vehicle body structure. These forces cause body vibrations, resulting in vibrations in the body itself (including components attached to the body, such as the tailgate).

[0004] Therefore, the vibrations of the vehicle's surfaces excite the air space within the interior, leading to an increase in airborne noise levels in the passenger compartment. This phenomenon, exemplified by the rumbling tire noise, is quite unpleasant from a passenger's perspective. Summary of the Invention

[0005] Therefore, the purpose of this invention is to reduce noise in the passenger cabin of a vehicle, or even, in the best case, to completely eliminate noise.

[0006] This objective is achieved by a method for reducing vehicle body vibration by means of an electric motor, and by means of an electric vehicle to implement the method. Further preferred embodiments can be found in the dependent claims.

[0007] According to the invention, an electric motor is used as a power unit for an electric vehicle to introduce force into the vehicle body or subframe, depending on which component the motor is supported on. This force counteracts the forces introduced into the vehicle body by road vibrations via the tires, the axles supporting the tires, and the subframe. In other words, the driving torque applied by the motor is varied during operation, such that a force is generated by the change in driving torque, which is distributed in opposite directions at the point of application of the force originating from road vibrations. The required torque is determined to minimize the forces input to the vehicle body, thereby minimizing vehicle body vibration and air noise in the passenger compartment.

[0008] There are essentially two distinct scenarios. In the first scenario, the motor is supported on or attached to the vehicle body, and the subframe is excited by the road surface via wheels supporting the road surface. The subframe thus vibrates, and this vibration is transmitted to the vehicle body. The impact of the excited subframe on the vehicle body can be quantified by determining the vibration of the vehicle body in, or at least in, the area of ​​the force introduction point or the subframe. In the force introduction point, this refers to the location where the subframe transmits force to the vehicle body via bearings. By generating a matching compensation drive torque caused by a change in the drive torque currently produced by the motor, a force opposite to the force introduced into the vehicle body by the subframe can be generated. This minimizes the vibration of the vehicle body and thus minimizes airborne noise generated by the vehicle body in the passenger compartment.

[0009] In the second scenario, the motor is supported to or attached to the subframe and is excited by the road surface via wheels supporting the road surface. Similarly, in this case, the subframe is elastically supported on the vehicle body. The subframe thus vibrates, and this vibration is transmitted to the vehicle body. By determining the vibration of the subframe, whether it is vibration on the vehicle body as described in the first scenario or vibration on the subframe itself, the force acting on it can be determined. Because the motor is also attached to the subframe, a matching compensation drive torque caused by changes in the drive torque currently generated by the motor can be generated, producing a force equal in magnitude but opposite in direction to the force acting on the subframe. This minimizes the vibration of the subframe, and thus minimizes the force transmitted to the electric vehicle body. Ultimately, this minimizes the vibration of the vehicle body and, consequently, the air noise in the passenger compartment.

[0010] Minimizing vehicle body vibration can be understood as minimizing the vibrational components in the vibration spectrum of the vehicle body, including components such as the rear hatch. By means of the method according to the invention, by minimizing the vibration transmitted from the subframe of the electric vehicle to its body, vibration is prevented from propagating through the body of the electric vehicle, thereby preventing noise generation inside the vehicle.

[0011] According to the present invention, a method is provided for reducing vibration of the vehicle body by means of an electric motor of an electric vehicle. The motor is a drive motor of the electric vehicle, which is powered by power electronics from a power battery.

[0012] The method includes determining the vibration of the subframe when the motor is mounted on the vehicle body or on the subframe, or determining the vibration of the vehicle body in the area where the force is introduced into the subframe. These two scenarios correspond to the two previously described options for supporting the motor on an electric vehicle. Determining vibration can be understood in particular as detecting vibration characteristics, which may include detecting the spectrum of the vibrational motion of the object under consideration using appropriate sensors.

[0013] The method according to the invention also includes determining the torque required for the motor to introduce force into the subframe or body, which counteracts the forces caused by the determined vibrations and acting on the subframe or body. The required torque is the drive torque, but in most cases, it has a significantly smaller magnitude than the drive torque currently generated by the motor for propelling the electric vehicle. For example, a conversion table can be used to convert the motor's drive torque into a resultant force applied to the body or subframe, thereby determining these values ​​through calculation or experiment. Alternatively, a typical rule-based approach can be used instead of the implementation table.

[0014] The driving torque of the electric motor is transmitted to the component on which the motor is mounted, namely the vehicle body or subframe. Equal but opposite forces are introduced into the component at each of the motor's support points at the front and rear (relative to the vehicle's longitudinal axis), and their combined effect constitutes the torque. In this case, the axis of rotation of the motor's rotor is arranged perpendicular to the vehicle's longitudinal axis. Due to this spatial arrangement of the motor in an electric vehicle, this method can only counteract the pitching motion of the vehicle body or subframe. Similarly, it cannot counteract the overall lifting motion (Hubbewegung) of the vehicle.

[0015] The method according to the invention further includes adjusting at least one drive signal of the motor such that a desired torque is generated by a change in the drive torque of the motor. The at least one drive signal may be a current component of the motor that generates torque.

[0016] In another embodiment of the method according to the invention, vibration can be determined by means of at least two sensors, preferably accelerometers. The determined acceleration includes the polarity of the vibration, which plays a decisive role in the introduction of the counter-force caused by the motor. Therefore, the method can also be performed based on the determined acceleration.

[0017] In another embodiment of the method according to the invention, at least two sensors may be arranged at different locations on the subframe or body relative to the longitudinal axis of the electric vehicle. In other words, a sensor may be arranged at the front of the subframe or at the front support point (or area thereof) of the subframe on the body, and a second sensor may be arranged at the rear of the subframe or at the rear support point (or area thereof) of the subframe on the body.

[0018] In other embodiments of the method according to the invention, at least two sensors may be arranged on the support points of the subframe or at a distance of up to 30 cm from the support points. Generally, the closer the sensors are to the vehicle body at the support points of the subframe, the more accurately the vibrations transmitted from the subframe to the vehicle body can be determined.

[0019] In another embodiment of the method according to the invention, determining vibration may include detecting vibration frequencies in the range of 30 Hz to 40 Hz. For this purpose, the determined spectrum may be filtered using a bandpass filter to capture only the vibration range relevant to the method according to the invention. Sound waves in the range of approximately 30 Hz to approximately 40 Hz are perceived by passengers as a rumbling sound inside the vehicle.

[0020] In another embodiment of the method according to the invention, determining the vibration may further include subtracting the vibration signals output by at least two sensors from each other. By subtracting the signal from the sensor located at the front of the subframe or the front support point of the subframe from the signal from the sensor located at the rear of the subframe or at (or near) the rear support point of the subframe, it can be shown that the unidirectional acceleration of the vehicle's lifting motion can be effectively eliminated, a signal that cannot be easily canceled without the method proposed herein. Consequently, the pitch motion of the subframe or body is amplified. Therefore, by subtracting the sensor signals from each other, the target signal can be optimized to determine the desired torque.

[0021] In another embodiment of the method according to the invention, vibration can be determined by means of at least four sensors, wherein the same number of sensors can be arranged on the right and left sides of the electric vehicle, extending centrally across the longitudinal axis of the electric vehicle. In other words, the sensors for detecting vibrations of the subframe or body can be arranged axially symmetrically, wherein the axis of symmetry can correspond to the centrally located longitudinal axis of the vehicle.

[0022] In another embodiment of the method according to the invention, determining vibration may include determining an average of signals from the right side and the left side of the vehicle, the signals corresponding to each other in terms of their position relative to the longitudinal axis of the vehicle. In other words, the signals may be averaged by these sensors on the left and right sides of the vehicle, which are arranged at the same height along the longitudinal axis.

[0023] According to the present invention, an electric vehicle having a motor is also provided, wherein the motor is supported on a subframe or on the vehicle body. The electric vehicle includes at least two sensors and control circuitry, the at least two sensors being arranged on the subframe or in a region of force introduction on the vehicle body, preferably at a force introduction location via the subframe, the control circuitry being connected to the at least two sensors and to a control unit of the motor, wherein the control circuitry is designed to perform the methods described above.

[0024] It goes without saying that the features described above and those to be explained below can be used not only in their respective specified combinations, but also in other combinations or on their own, without departing from the scope of the invention. Attached Figure Description

[0025] Other advantages and embodiments of the invention will become apparent from the description and drawings.

[0026] Figure 1 A schematic diagram of the rear of the vehicle is shown, which has a subframe and a motor supported on the subframe.

[0027] Figure 2 A schematic diagram of the rear of the vehicle is shown, which has a subframe and a motor supported on the body. Detailed Implementation

[0028] Figure 1 A schematic diagram of the rear of vehicle body 1 is shown, which has a subframe 2 and a motor 4 supported on the subframe. Wheel suspension 3 is supported on the subframe 2. The subframe 2 itself is supported at the rear of vehicle body 1. Black lines, not explicitly marked with reference numerals, indicate connecting elements between the various units.

[0029] During operation, the tires or wheels 8 and the axles supported on the subframe 2 vibrate due to road surface excitation. This vibration is transmitted to the subframe 2 at the first bearing point 51 and the second bearing point 52. Since torque is transmitted to the subframe 2 overall, the force acting on the first bearing point 51 is opposite to the force acting on the second bearing point 52. These two forces (and others mentioned below) are indicated by corresponding force arrows. Typically, that is, without applying the method according to the invention, these forces are transmitted from the subframe 2 to the vehicle body at the first subframe support point 61 and the second subframe support point 62.

[0030] However, as part of the method according to the invention, the vibration of the subframe 2 is determined or detected. The torque required by the motor 4 to introduce force into the subframe 2, which at least partially counteracts the force caused by the determined vibration and acting on the subframe 2, is then determined. Figure 1 The compensating force is represented by two force arrows pointing in opposite directions, which are transmitted to the subframe 2 at the first motor support point 71 and the second motor support point 72. The compensating force is generated by adjusting at least one drive signal of the motor 2, such that the required torque is produced by the change in the drive torque of the motor 4. This generates two forces acting at the first motor support point 71 and the second motor support point 72. These forces are opposite to the forces acting on the subframe at the first bearing point 51 and the second bearing point 52, and are large enough to minimize or, in optimal conditions, completely suppress the vibration state of the subframe 2. As a result, the subframe 2 does not transmit force to the vehicle body 1 at the first subframe support point 61 and the second subframe support point 62.

[0031] To determine the force or vibration, one can... Figure 1 Appropriate sensors, such as accelerometers, are placed at all the support points shown. Figure 1 The control circuit configured to perform the method according to the invention is not shown in detail. This control circuit is connected to the control unit of the sensor and motor 4. Figure 1 (Not explicitly shown in the text).

[0032] Figure 2 It shows the relationship with Figure 1 Compared to the slightly modified version, motor 4 is not mounted on subframe 2, but directly on the body 1. Additionally, the remaining structures correspond to... Figure 1 The structures shown are such that the same reference numerals are used for the same elements, and they are no longer described.

[0033] In this vehicle design, the force introduced from the subframe 2 to the body inevitably occurs at the first subframe support point 61 and the second subframe support point 62, causing vibration of the body 1. To minimize the impact of the force introduced from the subframe 2 on the body 1, compensating forces are generated at the first motor support point 71 and the second motor support point 72 by changing the drive torque (demand torque). Figure 1 Compared to the vehicle body shown, these forces are located on the vehicle body 1 rather than on the subframe 2.

[0034] exist Figure 1 and Figure 2 In both cases shown, in addition to the currently applied conventional drive torque, a compensating force is generated by selectively producing torque, which counteracts the action on the subframe 2 ( Figure 1 The force on the subframe 2 or on the body 1 ( Figure 2 The force introduced on the body 2. As a result, the vibration of the body 2 is minimized, at least within the predetermined target frequency range, and thus the air noise generated in the passenger compartment is minimized.

Claims

1. A method for reducing vibration of the body (1) of an electric vehicle by means of a motor (4), the motor being supported on the body (1) or subframe (2) of the electric vehicle, and the electric vehicle including wheel suspension (3) supported on the subframe (2), the method comprising: The vibration of the subframe (2) or the vibration of the vehicle body (1) in the region via the first force introduction part and the second force introduction part of the subframe (2), the first force introduction part and the second force introduction part being arranged at the front and rear of the wheel suspension (3), respectively, wherein the motor (4) is supported on the vehicle body (1) or the subframe (2); The torque generated by the motor (4) is determined to be required to introduce force into the subframe (2) or the body (1), the force counteracting the force caused by the determined vibration and acting on the subframe (2) or the body (1) at the first force introduction point and the second force introduction point; Adjust at least one drive signal of the motor (4) so ​​that the desired torque is generated by changing the drive torque of the motor (4).

2. The method of claim 1, wherein, The vibration is determined by means of at least two sensors, namely accelerometers.

3. The method of claim 2, wherein, The at least two sensors are arranged at different positions on the subframe (2) or the body (1) relative to the longitudinal axis of the electric vehicle.

4. The method of claim 2, wherein, The at least two sensors are arranged on the subframe (2) at a support point on the vehicle body (1) or at a distance of up to 30 cm from the support point.

5. The method according to any one of claims 1 to 4, wherein, Determining the vibration involves detecting the vibration frequency in the range of 30 Hz to 40 Hz.

6. The method according to any one of claims 2 to 4, wherein, Determining the vibration also includes subtracting the vibration signals output by the at least two sensors from each other.

7. The method of any one of claims 1 to 4, wherein, The vibration is determined by means of at least four sensors, wherein the same number of sensors are arranged on the right and left sides of the electric vehicle, extending centrally through the longitudinal axis of the electric vehicle.

8. The method of claim 7, wherein, Determining the vibration includes determining the average value of signals from the right side and the left side of the vehicle, the signals corresponding to each other in terms of their position relative to the longitudinal axis of the vehicle.

9. An electric vehicle having an electric machine (4), wherein The motor (4) is supported on the subframe (2) or the vehicle body (1), and the electric vehicle includes: Wheel suspension (3) supported on the subframe (2); At least two sensors are arranged on the subframe (2) or on the vehicle body (1) in the region of a first force introduction portion and a second force introduction portion of the subframe (2), the first force introduction portion and the second force introduction portion being arranged at the front and rear of the wheel suspension (3), respectively. A control circuit connected to the at least two sensors and to the control unit of the motor (4), wherein the control circuit is designed to perform the method according to any one of claims 1 to 8.

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