Acoustic vehicle warning system with speaker assembly for emitting acoustic signals in or at vehicle

Abstract

An acoustic vehicle warning system having a speaker assembly for emitting an acoustic signal within or at a vehicle is presented. The loudspeaker assembly comprises a loudspeaker (2) for emitting an acoustic signal as a function of an electrical output signal (SA), a control device (3) for generating an electrical input signal (SI), an amplifier device (4) for generating an electrical amplifier signal (SO) as a function of the electrical input signal (SI), and a filter circuit (5) for generating the electrical output signal (SA) as a function of the electrical amplifier signal (SO). The control device (3) is designed to determine an integrity state of the loudspeaker (2) as a function of a signal at the amplifier device (4) and / or the filter circuit (5) during operation of the loudspeaker assembly.

Description

TECHNICAL FIELD

[0001] The utility model relates to the acoustic vehicle warning system with loudspeaker assembly for emitting acoustic signal in or at the vehicle according to the preamble of claim 1. BACKGROUND

[0002] The loudspeaker assembly comprises a loudspeaker for emitting an acoustic signal in accordance with an electrical output signal, a control device for generating an electrical input signal, an amplifier device for generating an electrical amplifier signal in accordance with the electrical input signal and a filter circuit for generating the electrical output signal in accordance with the electrical amplifier signal.

[0003] The loudspeaker assembly may, for example, be a component of an acoustic vehicle warning system (English: Acoustic Vehicle Alert System, abbreviated AVAS) in which an acoustic warning sound is generated in order to alert to an ongoing driving motion in the case of a vehicle which is low-noise, in particular an electric vehicle. For example, such a warning system can be designed to generate a sound which is similar to that of an internal combustion engine motor, so that other road users, in particular pedestrians, are able to perceive the approach of the vehicle acoustically. It can be provided that the warning sound is generated, for example, always below a predetermined driving speed, for example below 20 km / h or 30 km / h, wherein the point of departure is that the rolling noise and the wind noise of the vehicle are loud enough and perceptible to other road users at higher speeds.

[0004] The acoustic vehicle warning system is relevant to safety. It must therefore be ensured that the acoustic warning system is operationally ready at the start of driving and even during driving, so that the acoustic warning system is able to assume its due warning function in operation. SUMMARY

[0005] The task of the utility model is to provide an acoustic vehicle warning system with a loudspeaker assembly which can reliably assume a safety-relevant warning function.

[0006] The task is solved by the subject matter having the features of claim 1.

[0007] The signal at the amplifier device and / or the filter circuit is therefore fed directly or indirectly to the control device, and the control device is configured to ascertain the integrity state of the loudspeaker in operation of the loudspeaker assembly in accordance with the signal at the amplifier device and / or the filter circuit.

[0008] The loudspeaker assembly has a loudspeaker which is designed to convert an electrical output signal into an acoustic signal and to emit the acoustic signal. The acoustic signal can be, for example, a warning sound which is similar, for example, to the sound of an internal combustion engine motor, or can be a harmonic signal, for example, a sinusoidal signal.

[0009] The electrical output signal is generated by using a control device, an amplifier device and a filter circuit. The control device is designed to generate an electrical input signal and to emit it to the amplifier device. The amplifier device amplifies the input signal and emits the amplifier signal to the filter circuit. The filter circuit generates an output signal from the electrical amplifier signal and emits the output signal to the loudspeaker which converts the output signal and emits it as an acoustic signal outwardly.

[0010] In the context of an acoustic vehicle warning system, the loudspeaker can be mounted, for example, outside the vehicle, for example, in the area of a front or rear bumper or in the area of the vehicle underbody.

[0011] In the context of an acoustic vehicle warning system, the control device can be designed, for example, to generate the electrical input signal for generating the electrical output signal when the driving speed of the vehicle is below a predetermined value, for example, below 20 km / h or 30 km / h, in order to emit an acoustically perceptible sound as a signal to other road users that the vehicle is in motion, especially in the case of slow driving speeds.

[0012] Especially in use on an acoustic vehicle warning system, it must be ensured that the loudspeaker assembly can fulfill its prescribed function in operation. If the integrity status of the warning system is affected, for example, when a connection to the loudspeaker is interrupted or a damage occurs at the loudspeaker, countermeasures should be taken as soon as possible to restore the loudspeaker assembly.

[0013] For this reason, the control device is configured to ascertain the integrity status of the loudspeaker from a signal at the amplifier device and / or at the filter circuit when the loudspeaker assembly is in operation. The signal can be, for example, the amplifier signal at the output of the amplifier device or the electrical output signal at the output of the filter circuit. However, the signal can also be another signal which occurs in the context of the operation of the loudspeaker assembly, for example, a supply signal of the amplifier device which represents the power supply to the amplifier device.

[0014] The control device is configured to monitor the integrity state of the loudspeaker during operation. Thus, the control device learns the integrity state of the loudspeaker not only before commissioning, for example before starting a journey, but also during operation, i.e. during the time in which the control device generates and issues the electrical input signal to the amplifier device, which generates and issues the electrical amplifier signal to the filter circuit, which in turn generates and issues the electrical output signal to the loudspeaker. Thus, during the generation of the signal for generating the acoustic signal output via the loudspeaker, the control device checks whether the loudspeaker is in a ready-to-operate state. If the evaluation of one or more signals does not lead to this being the case, countermeasures are initiated, for example by prohibiting the vehicle from continuing to operate or by generating a warning prompt, for example via optical output means in the vehicle, such as a vehicle display.

[0015] In one design variant, the control device is configured to learn the integrity state of the loudspeaker from the electrical output signal during operation of the loudspeaker assembly. Thus, the control device carries out a check from the electrical output signal at the output of the filter circuit and evaluates the electrical output signal in order to deduce the integrity state of the loudspeaker from the evaluation result.

[0016] For example, the loudspeaker assembly can have a check circuit which is designed to generate a check signal from the electrical output signal. The check circuit can be designed, for example, to intercept the voltage at the output of the filter circuit and to generate a check signal from this voltage. By evaluating the check signal, the control device can deduce the integrity state, for example, by checking the check signal against a predetermined, stored expected signal.

[0017] In one design variant, the control device is configured to compare the check signal with a threshold value and to learn the integrity state in dependence on the comparison result. For example, the control device can check whether the check signal is above the threshold value. If this is the case, it can be an indication that a fault is present at the loudspeaker, since the load at the filter circuit deviates from the expected load and the filter circuit is thus operated without a load, for example as a result of a break in the connection to the loudspeaker.

[0018] The filter circuit can be, for example, a low-pass filter, which has a facility consisting of one or more inductances and one or more capacitances. The loudspeaker represents a load for the filter circuit, which provides a predetermined impedance, for example an impedance of 4 ohms, at the output of the filter circuit. If the loudspeaker fails, for example due to an interruption of the electrical connection between the filter circuit and the loudspeaker, an open-circuit operation of the filter circuit can occur, i.e. in effect no load is coupled. This influences the output signal present at the output of the filter circuit, so that this output signal deviates from the signal expected under the prescribed load. The check signal generated by the check circuit is related to the output signal and thus, for example, reflects the amplitude of the output signal. If a deviation from the prescribed load state at the output of the filter circuit occurs due to a failure at the loudspeaker, this leads, for example, to an increase in the amplitude of the output signal and thus to an increase in the check signal, which is correspondingly recognized by evaluating the check signal and can be taken into account for determining the integrity state of the loudspeaker.

[0019] In one design, the check circuit has a voltage divider circuit for dividing the electrical output signal. The output signal at the output of the filter circuit in operation comes from the amplifier signal at the output of the amplifier device and is thus amplified. In order to reduce the voltage at the check circuit, there is provided a voltage divider circuit, which is composed, for example, of a combination of two resistors in series, and through which the output signal is divided in accordance with the ratio of the resistors and thus its amplitude is reduced.

[0020] In one design, the check circuit has a rectifier circuit for rectifying the electrical output signal. The output signal is present, for example, as an analog signal for actuating the loudspeaker in the audible acoustic range, for example below 10 kHz, preferably equal to or less than 5 kHz. In order to deliver the check signal to the input of the control device, the rectifier circuit rectifies the electrical output signal, resulting in a direct voltage signal.

[0021] The rectifier circuit can have, for example, one or more diodes, for example in combination with one or more capacitors, through which the rectification of the output signal at the output of the voltage divider circuit is achieved.

[0022] In one design, the check circuit is configured to conduct the check signal to the signal input of the control device. The check signal is thus directed to the control device, which can evaluate the check signal, for example by comparing it with a predetermined threshold value, in order to infer the integrity state of the loudspeaker from the evaluation result.

[0023] The signal input of the control device can be, for example, an ADC input for digitizing the examination signal. At the ADC input, the examination signal, which can be time- varying, is digitized and processed within the control device, so that from the examination signal the integrity state of the loudspeaker can be inferred.

[0024] In one design variant, the amplifier device is a so-called class-D amplifier. A class-D amplifier converts an analog input signal into a pulse-width-modulated signal, which is amplified in a power output stage circuit. The amplifier signal emitted from the amplifier device thus corresponds to the pulse-width-modulated signal generated from the input signal provided by the control device. Such a class-D amplifier has a high efficiency and low electrical losses.

[0025] In one design variant, the amplifier device is designed for comparing the input signal with a predetermined triangular signal of a pulse sequence frequency in order to generate the pulse-width-modulated signal. The pulse sequence frequency, i.e. the frequency of the pulse sequence of the triangular signal, can thus be in the range of, for example, 100 kHz to 500 kHz, for example in the range of 300 kHz to 400 kHz. By comparing the input signal with the triangular signal, a pulse-width-modulated signal is generated from the triangular signal, which can then be amplified in a power output stage.

[0026] In one design variant, the filter circuit is designed for converting the pulse-width-modulated signal into an analog signal in order to generate the electrical output signal. If the input signal is a harmonic sinusoidal signal, an analog sinusoidal signal is again generated from the conversion in the filter circuit. The filter circuit can be designed, for example, as a low-pass filter, which generates an output signal as an analog signal from a pulse-width-modulated signal at the pulse sequence frequency.

[0027] The filter circuit can in particular be designed as a passive circuit. Preferably, the filter circuit is coordinated with the impedance of the loudspeaker and, in addition, with the frequency of the pulse-width-modulated signal.

[0028] In one design variant, the filter circuit has an inductance and a capacitance in series. The amplifier signal is applied to the filter circuit in such a way that the amplifier signal is applied to the inductance and the capacitance. The output signal is in turn applied to the capacitance in such a way that the loudspeaker is connected to the node between the inductance and the capacitance and thus intercepts the output signal via the capacitance.

[0029] In one design, the control device is configured to ascertain the integrity status of the loudspeaker from the signal detected at the amplifier device when the loudspeaker assembly is in operation. In addition to ascertaining the integrity status from the output signal or alternatively, the control device can (also) ascertain the integrity status from the signal detected at the amplifier device. In this context, the control device does not ascertain the integrity status at the output of the filter circuit, but rather from the signal present directly in or at the amplifier device.

[0030] For example, the control device can be configured to determine a characteristic value indicative of the power supply to the amplifier device from the signal detected at the amplifier device and to ascertain the integrity status of the loudspeaker from the characteristic value. Thus, the control device detects a characteristic value indicative of which power is delivered to the amplifier device in operation. From a comparison of the characteristic value with an expected value in a normal, prescribed operation, it can be concluded that the integrity status of the loudspeaker assembly, in particular when the characteristic value deviates from the expected value, for example, from a comparison with a threshold value.

[0031] For example, the control device can be configured to determine a characteristic value indicative of the power supply to the amplifier device from a current measurement at a current measurement resistor in the supply path of the amplifier device. For example, the current measurement resistor can be connected as a low-ohmic resistor in the supply path of the amplifier device. The supply of the amplifier device takes place via the supply path and thus via the current measurement resistor. From the voltage drop at the current measurement resistor, the current in the supply path can be measured and from this the power supply to the amplifier device in operation can be concluded.

[0032] For example, the expected current flowing in the supply path of the amplifier device in a prescribed operation can be determined in an initial calibration routine. If the current measured in operation deviates from the expected current, for example by a predetermined amount, for example by more than 20%, for example more than 30%, preferably more than 50% of the effective value of the expected current, it is concluded that the loudspeaker assembly is not in a prescribed state and thus in a faulty integrity status.

[0033] The amplifier device can be configured to amplify the input signal in one or more predetermined frequency ranges depending on a configurable input parameter or according to a predetermined amplification function. The expected current values for one or more different amplification functions can be stored in the control device, for example, so that it can be assessed in operation whether there is a deviation from the expected current values.

[0034] The loudspeaker assembly is a component of an acoustic vehicle warning system.

[0035] A method for operating a loudspeaker assembly for emitting an acoustic signal within or at a vehicle comprises generating an electrical input signal by a control device, generating an electrical amplifier signal by an amplifier device depending on the electrical input signal, generating an electrical output signal by a filter circuit depending on the electrical amplifier signal, and emitting an acoustic signal by a loudspeaker depending on the electrical output signal. During operation of the loudspeaker assembly, the control device learns an integrity status of the loudspeaker depending on signals at the amplifier device and / or at the filter circuit.

[0036] The advantages and advantageous design solutions described above for the loudspeaker assembly apply equally to the method, so in this respect reference is made to the preceding explanations. BRIEF DESCRIPTION OF DRAWINGS

[0037] The basic idea of the present utility model will be explained in more detail below with reference to embodiments shown in the drawings. Therein:

[0038] Figure 1 schematic view of a vehicle with an acoustic vehicle warning system;

[0039] Figure 2 schematic view of a loudspeaker assembly of an acoustic vehicle warning system;

[0040] Figure 3 schematic view of a check circuit of a loudspeaker assembly;

[0041] Figure 4A view showing an example of an input signal generated by a control device;

[0042] Figure 4B view showing an example of a triangular signal for generating a pulse width modulated signal in an amplifier device;

[0043] Figure 4C view showing an amplifier signal generated by an amplifier device;

[0044] Figure 5 circuit view of a check circuit together with a filter circuit;

[0045] Figure 6A view showing signals in a check circuit (top) and an output signal in a normal integrity status (bottom); and

[0046] Figure 6B view showing signals in a check circuit (top) and an output signal in a faulty integrity status (bottom). DETAILED DESCRIPTION

[0047] Figure 1A schematic view of a vehicle 1 with a vehicle warning system is shown, in which a loudspeaker 2 for emitting an acoustic warning signal is arranged on the outside of the vehicle 1, for example in the region of the front bumper or rear bumper of the vehicle 1, or in the region of the bottom of the vehicle 1 (e.g. Figure 1 This is shown schematically, but is not limited thereto in any way.) The control device 3 is operatively connected to the loudspeaker 2 in order to control the loudspeaker 2 to emit acoustic signals.

[0048] In an acoustic vehicle warning system, for example, a warning sound can be generated that is similar to the sound of a conventional internal combustion engine, in order to, for example, alert other road users to the presence of vehicle 1 in a low-noise vehicle (particularly an electric vehicle). The vehicle warning system can be designed, for example, to generate such a warning sound at slow driving speeds, for example, below 20 km / h or 30 km / h. In contrast, this is generally not necessary at higher speeds because the rolling noise and wind noise generated are similar to the noise generated by other vehicles.

[0049] like Figure 2 As shown in FIG, the control device 3 is designed to generate an input signal S in conjunction with the vehicle warning system. I The input signal S is fed to an amplifier device 4 which is designed in particular as a so-called class D amplifier. I And output amplifier signal S O The amplifier signal is sent to the filter circuit 5, and the filter circuit is based on the amplifier signal S O Generate output signal S A And transmit it to speaker 2.

[0050] The amplifier device 4 is preferably designed as a class D amplifier with a power output stage circuit, which is designed in particular for outputting a power signal according to the input signal S I Generate a pulse width modulated amplified signal and use the pulse width modulated signal as the amplifier signal S O Output.

[0051] like Figure 4A In the example, according to the sinusoidal oscillation, the input signal S I is supplied to the amplifier device 4, for example as an analog signal. The amplifier device 4 converts the input signal S I and Figure 4B The triangular signal S shown in FIG has a predetermined pulse sequence frequency (for example, between 100 kHz and 500 kHz, for example, between 300 kHz and 400 kHz) Cis compared in order to generate a pulse width modulated signal from the comparison result, which can be amplified with high efficiency and which, in Figure 4C is shown in the middle.

[0052] The resulting amplifier signal S O is fed to a filter circuit 5, for example to a combination of inductances and capacitances for providing a low-pass filter circuit, in order to generate from the pulse width modulated amplifier signal S O an analog output signal S A which is fed to the loudspeaker 2 and is converted into an acoustic signal and output by the loudspeaker 2.

[0053] Figure 2 The loudspeaker assembly shown in the middle is relevant to safety in connection with a vehicle warning system for generating a warning sound which alerts other traffic participants that the vehicle 1 is driving. In order to check the integrity status of the loudspeaker 2 at such a loudspeaker assembly, in order thus to check whether the loudspeaker 2 is connected to the filter circuit 5 in a prescribed manner and thus ready for operation, there is provided a check circuit 6 which generates a check signal from the output signal S A and feeds it, for example, to a signal input 30 of a control device 3, for example to an ADC signal input for digitizing the check signal, the control device evaluating the check signal and deriving the integrity status of the loudspeaker 2 from the check signal.

[0054] Figure 3 An example of such a check circuit 6 is shown in the middle. The check circuit 6 is connected in the line path between the filter circuit 5 and the loudspeaker 2 in order to receive the output signal S A and feed it as a voltage signal U in to the check circuit 6. The check circuit 6 is coupled here via a coupling capacitor Cl to the line path and feeds the output signal S A to a voltage divider, which is formed by resistors Rl, R2, and at which the output signal S A is divided in order to reduce the amplitude of the output signal S . The voltage signal is rectified via a diode Dl acting as a rectifier circuit and a capacitor C2. A resistor R3 in parallel to the capacitor C2 is used to enable discharging of the capacitor C2 when the system is switched off. The check circuit 6 is coupled via a resistor R4 to a signal input 30 of the control device 3 in order to feed the rectified voltage signal as a check signal U ADC to the signal input 30 of the control device 3.

[0055] The control device 3 evaluates the check signal U ADC in order to derive the integrity status of the loudspeaker 2 from the check signal U ADCThe integrity state of loudspeaker 2 is inferred, in particular in order to ascertain whether loudspeaker 2 is connected in a proper manner to filter circuit 5 or whether the connection line between filter circuit 5 and loudspeaker 2 is possibly interrupted.

[0056] Figure 5 An example of a connection diagram is shown, in which the filter circuit 5 is formed by a combination of an inductor L0 and a capacitor C0 in each of the positive and negative connection paths of the loudspeaker 2. At the positive input of the loudspeaker 2, the positive amplifier signal S of the amplifier device 4 is fed via the filter circuit 5. O , at the negative input terminal of speaker 2, feed the inverted negative amplifier signal S O' . Amplifier signal S O 、S O' The input terminals of the respective speakers are connected to the node between the inductor L0 and the capacitor C0, thereby outputting the signal S A 、S A' The power drops across the respective capacitors C0 and is delivered to the loudspeaker 2. The filter circuit 5 acts as a low-pass filter and converts the pulse width modulated amplifier signal S O 、S O' Converted into an analog low-pass filtered output signal S A 、S A' .

[0057] The loudspeaker 2 is a load for the filter circuit 5 and has an impedance R0 to which the filter circuit 5 is adapted.

[0058] If the line between the loudspeaker 2 and the filter circuit 5 is interrupted and the load is removed accordingly, so that the filter circuit 5 operates in an open circuit, the output signal S A 、S A' Also changes due to changes in load conditions. In particular, the output signal S may A 、S A' The signal is improved.

[0059] Figure 6A 、 6B The output-side signal of the filter circuit 5 and also the signal in the test circuit 6 are shown in FIG.

[0060] therefore, Figure 6A The signals are shown in the normal integrity state when the loudspeaker 2 is connected correctly. Figure 6A The upper figure shows the signal S in the test circuit 6 after voltage division by resistors R1 and R2. P1 (This is like Figure 5 As can be seen), and the rectified signal S at the output of the rectifier circuit formed by the diode D1 and the capacitor C2 P2 .Figure 6A The output signal S at the output of the filter circuit 5 is also shown in the lower figure. A 、S A' .

[0061] In contrast, Figure 6B The signal is shown in the case of a missing load at the filter circuit 5 due to an interruption in the connection to the loudspeaker 2 in a faulty integrity state. Figure 6B The upper diagram shows the signal S at the output of the voltage divider R1 , R2 of the test circuit 6 . P1 , and the rectified signal S at the output of the rectifier circuit formed by diode D1 and capacitor C2 P2 , and the figure below shows the output signal S at the output end of the filter circuit 5 A 、S A' .

[0062] In accordance with Figure 6A 、 6B In the example of Figure 4A The 5 kHz sinusoidal oscillation is used as the input signal S I , and sent to the amplifier device 4, the amplifier device amplifies the signal S O 、S O' The filter circuit 5 transmits the amplifier signal S O 、S O' Converted into output signal S A 、S A' .

[0063] like Figure 6A (Bottom) It can be seen that in the specified fault-free integrity state, when the loudspeaker 2 is connected as specified, the output signal S A 、S A' has a constant amplitude. Accordingly, the signal S at the output of the voltage divider of the test circuit 6 is P1 has a constant amplitude, resulting in a signal S P1 The constant effective value of the corresponding signal level signal S P2 ,like Figure 6A (above) shown.

[0064] On the other hand, if the connection to the loudspeaker 2 is interrupted, the Figure 6B signal, where the output signal S A 、S A' There is a significant signal increase and, accordingly, the signal S at the output of the voltage divider of the test circuit 6 P1 A signal boost also occurs, and accordingly a rectified signal S P2 The signal is improved.

[0065] The rectified signal S P2 The control device 3 is fed as a test signal to the signal input 30 of the control device 3, for example, by the following means: P2 Evaluate, that is, the signal S P2 is compared with a threshold and the integrity status is inferred based on the threshold comparison. For example, if the signal S P2 is higher than the threshold, it is inferred that the output signal S A 、S A' There is a signal increase in , which indicates that the connection to loudspeaker 2 is interrupted, thereby identifying a faulty integrity state.

[0066] In accordance with Figure 6A 、 6B In the example, Figure 6A As shown in the figure above, under the specified integrity state, the signal S P2 has a value of about 0.6 V. In contrast, Figure 6B In the faulty integrity state, the signal S P2 It has a maximum value of approximately 4 V and a median value of approximately 2.6 V. For example, the threshold value is set to a value of 1 V, so that a positive (no fault) or negative (faulty) integrity status can be derived from the signal comparison with the threshold value.

[0067] For example, the signal S supplied to the control device 3 via the signal input 30 P2 It can be digitized in the control device 3 and processed in digital form within the control device 3. The threshold value is preferably permanently programmed in the control device 3.

[0068] If a faulty integrity state is detected, countermeasures can be initiated, for example, by outputting a warning message in the interior of vehicle 1 via an output device, such as a display screen.

[0069] In addition to the output signal S A 、S A' In addition to checking the integrity status, the integrity status can also be checked based on the signal of the amplifier device 4, such as Figure 2 This is plotted in .

[0070] A so-called shunt, which functions as a current measurement resistor R, can thus be connected in the supply path of the amplifier device 4, which is connected to the supply voltage Vo via the supply path. The voltage which drops via the shunt can be led to a signal input 31 of the control device 3, which evaluates the voltage and learns the through current in the supply path. From the through current, the power supply which is delivered to the amplifier device 4 in operation can be determined. The power supply can be evaluated in order to learn whether the loudspeaker 2 is connected as a load in a prescribed manner.

[0071] For example, in an initial calibration routine before commissioning, which power supply is to be expected in a prescribed operation of the amplifier device 4 can be determined. For different amplification functions for generating different signals, the expected power values can be determined individually here and saved, for example, in a comprehensive characteristic curve stored in the control device 3. In operation, the power supply determined via the shunt is compared with the expected power values in accordance with the adjusted amplification function of the amplifier device 4. If deviations occur, it can be concluded that the integrity state of the loudspeaker 2 is not prescribed.

[0072] The basic idea of the utility model is not limited to the preceding embodiments, but can also be realized in other ways.

[0073] The loudspeaker assembly of the type described can be used, in particular, in a vehicle warning system in order to learn the integrity state of the loudspeaker in operation.

[0074] However, the loudspeaker assembly can also be used in other applications in a vehicle.

[0075] List of reference signs

[0076] 1 vehicle

[0077] 2 loudspeaker

[0078] 3 control device

[0079] 30, 31 input

[0080] 4 amplifier device (output stage)

[0081] 5 filter circuit

[0082] 6 check circuit

[0083] C0 capacitance of the filter circuit

[0084] C1, C2 capacitor

[0085] D1 diode

[0086] L0 inductance of the filter circuit

[0087] R0 loudspeaker impedance

[0088] R1-R4 resistors

[0089] R current measurement resistor

[0090] S I input signal

[0091] S O , S O' amplifier signal

[0092] S A , S A' output signal

[0093] S P1 , S P2 signal in the checking circuit

[0094] U ADC checking signal

[0095] V0 supply voltage

Claims

1. Acoustic vehicle warning system with a loudspeaker assembly for emitting an acoustic signal within or at a vehicle (1), wherein The loudspeaker assembly has Loudspeaker (2) for emitting an acoustic signal in dependence on an electric output signal (S A ) A control device (3) for generating an electrical input signal (S I ) An amplifier device (4) for generating an electrical amplifier signal (S O ) from the electrical input signal (S I ), and a filter circuit (5) for generating the electrical output signal (S A ) from the electrical amplifier signal (S O ), The signal at the amplifier device (4) and / or the filter circuit (5) is fed directly or indirectly to the control device (3), and the control device (3) is configured to ascertain the integrity state of the loudspeaker (2) from the signal at the amplifier device (4) and / or the filter circuit (5) when the loudspeaker assembly is in operation.

2. The acoustic vehicle alerting system of claim 1, wherein, The control device (3) is configured to learn the integrity state of the loudspeaker (2) from the electrical output signal (S A ) while the loudspeaker assembly is in operation.

3. The acoustic vehicle alerting system of claim 2, wherein The electrical output signal (S A ) is generated by means of an evaluation circuit (6) for generating a test signal (U ADC ).

4. The acoustic vehicle alerting system of claim 3, wherein, The control device (3) is configured to compare the check signal (U ADC ) with a threshold value and to ascertain the integrity state of the loudspeaker (2) depending on the comparison result.

5. The acoustic vehicle alerting system of claim 3, wherein, The check circuit (6) has a voltage divider circuit for voltage dividing the electrical output signal (S A ).

6. The acoustic vehicle alerting system of claim 3, wherein, The check circuit (6) has a rectifier circuit for rectifying the electrical output signal (S A ).

7. The acoustic vehicle alerting system of claim 6, wherein, The rectifier circuit has at least one diode (D1).

8. The acoustic vehicle alerting system of claim 3, wherein, The check circuit (6) is configured to conduct the check signal (U ADC ) to a signal input (30) of the control device (3).

9. The acoustic vehicle alerting system of claim 8, wherein, The signal input (30) is an ADC input for digitizing the examination signal (U ADC ) 10. The acoustic vehicle alerting system of claim 1, wherein, The amplifier device (4) is a class-D amplifier.

11. The acoustic vehicle alerting system of claim 1, wherein, The amplifier device (4) is configured to generate an amplifier signal (S O ) as a pulse width modulated signal in dependence on the input signal (S I ).

12. The acoustic vehicle alerting system of claim 11, wherein, The amplifier device (4) is configured to compare the input signal (S I ) with a triangular signal having a predetermined pulse sequence frequency in order to generate the pulse width modulated signal.

13. The acoustic vehicle alerting system of claim 11, wherein, The filter circuit (5) is configured to convert the pulse width modulated signal into an analog signal in order to generate the electrical output signal (S A ).

14. The acoustic vehicle alerting system of claim 1, wherein, The filter circuit (5) has an inductance (Lo) and a capacitance (Co) in series, wherein an amplifier signal (S O ) of the amplifier device (4) is applied to the inductance (Lo) and the capacitance (Co) and the output signal (S A ) is applied to the capacitance (Co).

15. The acoustic vehicle alerting system of claim 1, wherein, The control device (3) is configured to ascertain the integrity state of the loudspeaker (2) from the signal detected at the amplifier device (4) when the loudspeaker assembly is in operation.

16. The acoustic vehicle alerting system of claim 15, wherein, The control device (3) is configured to determine a characteristic value indicative of the power supply to the amplifier device (4) from the signal detected at the amplifier device (4) and to ascertain the integrity state of the loudspeaker (2) from the characteristic value.

17. The acoustic vehicle alerting system of claim 16, wherein, The control device (3) is configured to determine a characteristic value indicative of the power supply to the amplifier device (4) from a current measurement at a current measurement resistor (R) in the supply path of the amplifier device (4).

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