DE102018112715A1 - Sound generation system for an exhaust system of an internal combustion engine of a motor vehicle - Google Patents

Abstract

A sound generation system (10) for an exhaust system (12) of an internal combustion engine of a motor vehicle is provided with an electrically operable sound generating device (16) for generating sound outside the vehicle interior and for optionally superposing the sound with the sound of the internal combustion engine carried by the exhaust gas flow and with a sound sensor (18) adapted to detect the sound generated by the sound generating device in combination with sound carried by the exhaust flow outside the exhaust system (12), the sound sensor (18) being disposed in a housing (20) at least a sound transmissive wall portion (22) and in fluid communication with an exhaust gas carrying pipe (14), and wherein depending on the current temperature of the housing (20) or in the housing (20) an exhaust gas flow through the housing (20) by a Actuator (26) is either blocked or released.

Description

The present invention relates to a sound generation system for an exhaust system of an internal combustion engine of a motor vehicle.

In-vehicle sound generation systems are used, for example, to superimpose sound from the exhaust gas-borne sound of the internal combustion engine, such that the sound carried by the exhaust gas flow is attenuated or eliminated. In this context, sound generation systems are also referred to as active sound attenuation systems.

Alternatively or additionally, such sound generating systems can be used to supplement the sound carried by the exhaust gas flow by sound generated by a sound generating device in such a way that a total of a sum sound or a soundscape results, which is appealingly perceived by a vehicle user. In this case of application one also speaks of sound design.

In order to detect a total sound resulting from a superposition of the sound carried by the exhaust gas flow with a sound generated by a sound generating device, sound sensors are used. The sound sensors are mounted in known sound generating systems in the exhaust system in order to detect as reliably as possible the aforementioned sum sound can. Frequently, the sound sensors are mounted in a separate sound-permeable housing in close proximity to the exhaust system.

The disadvantage here is that the housing is arranged in the wet area of the vehicle, so that especially in winter there is a risk that the housing icing and the sound transmission of the housing is affected, which in turn affects the reliability of the sound detection.

It is thus an object of the present invention to provide a sound generation system for an exhaust system of an internal combustion engine that functions reliably regardless of the weather conditions.

This object is achieved by a sound generation system for an exhaust system of an internal combustion engine of a motor vehicle with an electrically operable sound generating device for generating sound outside the vehicle interior and the optional interference of the sound with the sound carried by the exhaust gas sound of the engine and with a sound sensor which is adapted to detect the sound generated by the sound generating device in combination with sound carried by the exhaust flow outside the exhaust system, wherein the sound sensor is arranged in a housing having at least one sound-transmitting wall section and which is in fluid communication with an exhaust pipe, and wherein from the current temperature of the housing or in the housing an exhaust gas flow through the housing is selectively blocked or released by an actuator.

The sound generation system according to the invention has the advantage that a residual heat of the exhaust gas flow can be used to heat the housing and thus to free the housing if necessary from a layer of ice. The fact that the actuator selectively blocks or releases the exhaust gas flow, a temperature control can be done so that the housing is sufficiently heated, but the sound sensor is protected against overheating.

The housing interior is in fluid communication with the exhaust-carrying pipe, for example, via a conduit, the housing having an outlet opening, in particular wherein the actuator is arranged and switchable so that the outlet opening is exhausted in dependence on the current temperature and the position of the actuator or not , Thus, depending on the current temperature and the position of the actuator, the exhaust gas can flow through the line into the housing and flow out through the outlet opening. That is, as long as the actuator is switched accordingly, warm exhaust gas may flow through the housing until the housing is sufficiently warmed to melt an optional ice layer.

In order to avoid that a sound pressure from the exhaust-gas-carrying pipe propagates into the housing and falsifies the measurement, the line which fluidly connects the housing to the exhaust-carrying pipe is significantly smaller in diameter than the exhaust-carrying pipe, preferably at least 50% smaller ,

In particular, the line is dimensioned so that no pressure pulsations in the desired measurement range of the sound sensor are introduced into the housing. The measuring range of the sound sensor is usually between 25Hz and 1000Hz.

The outlet opening may be covered with a gas-permeable material to prevent dirt or water from entering the housing.

According to one embodiment, an exhaust gas flow through the housing is below released a predetermined limit temperature. An exhaust gas flow through the housing is therefore only released if the risk of icing exists, while avoiding unnecessary heating of the sound sensor. At warm ambient temperatures, for example in summer, an additional heating of the housing is not necessary and not desirable.

For example, the actuator preferably has a thermostat inside the housing, which releases an exhaust gas flow through the housing when the temperature falls below a predetermined limit temperature and blocks an exhaust gas flow through the housing above the predetermined limit temperature. By means of such a thermostat, a temperature control in the housing can be done in a simple manner.

The thermostat may comprise a bimetal which deforms depending on the current temperature, in particular a bimetallic strip. As a result of the deformation, an exhaust gas flow through the outlet opening can be released or blocked, in particular by the overflow opening being released or closed. As a result, the sound generation system is simple and inexpensive to produce.

In particular, the thermostat mechanically closes a flow path through the housing above the predetermined limit temperature. The sound generation system, in particular the actuator, is characterized by little error prone, since no electronic components are necessary to regulate an exhaust gas flow through the housing.

In the housing, a first and a second chamber are formed, wherein the outlet opening is arranged in the second chamber and wherein the second chamber is fluidically connectable to the first chamber via an overflow and the overflow as a function of the current temperature of the actuator selectively closed or is opened. This has the advantage that the actuator, in particular the thermostat, can be arranged inside the housing and at a distance from an outer wall of the housing. In this way, the actuator, in particular the thermostat, protected from contamination and damage, since it is spatially isolated from the wet area of the vehicle.

The chambers are formed for example by an inner wall in the housing, wherein the overflow opening and the thermostat are arranged on the inner wall.

According to one embodiment, the line fluidically coupled to the exhaust-carrying pipe leads into the first chamber. Consequently, since the exit opening is located in the second chamber, a flow path through the housing is only released if the overflow opening connecting the first and second chambers is also released.

The sound-permeable wall section is preferably part of the outer wall of the first chamber. The sound sensor can thus reliably detect ambient sound around the housing. Preferably, the sound sensor is arranged in the first chamber.

The sound-permeable wall section, for example, arranged so that it is heated at exhaust gas flow, in particular comes into contact with the exhaust gas. In this way it is ensured that a sound sensor can reliably measure a total sound, which results from a superposition of the sound carried by the exhaust gas flow with a sound generated by the sound generating device, even at low ambient temperatures and humid weather.

The wall portion may be flexible at least in some areas. As a result, the wall section can be elastically deformed during operation of the sound generation system, for example during a driving operation, as a result of which mechanical contaminants can be removed from the wall section. If, for example, a dirt crust has formed on the flexible wall section, this crust can be broken up and detached by the deformation of the wall section.

The housing is, for example, in mechanical connection with a body component and / or with a suspension of the exhaust-carrying pipe. In this way, vibrations occurring during driving are forwarded to the housing, which can also serve to shake off a dirt and / or ice layer.

Since the housing is disposed in a wet area of the vehicle and thus must withstand the prevailing weather conditions, the housing is preferably made of a weatherproof material.

• - 1 schematisch ein erfindungsgemäßes Schallerzeugungssystem für ein Abgassystem eines Verbrennungsmotors eines Kraftfahrzeugs,
• - 2 eine vergrößerte Teilansicht des erfindungsgemäßen Schallerzeugungssystems aus 1 und
• - 3 den Teil des erfindungsgemäßen Schallerzeugungssystems aus 2 in einem verformten Zustand.

Further advantages and features of the invention will become apparent from the following description and from the following drawings, to which reference is made. In the drawings show:

• - 1 1 schematically a sound generation system according to the invention for an exhaust system of an internal combustion engine of a motor vehicle,
• - 2 an enlarged partial view of the sound generation system according to the invention 1 and
• - 3 the part of the sound generation system according to the invention 2 in a deformed state.

1 shows a sound generating system according to the invention 10 for an exhaust system 12 an internal combustion engine. From the exhaust system 12 is in 1 for the sake of simplicity, only a part of an exhaust pipe 14 represented, which is flowed through in the arrow direction by an exhaust gas.

The sound generation system 10 includes a sound generating device 16 for generating sound outside the vehicle interior for the optional superimposition of the sound with the sound of the combustion engine carried by the exhaust gas flow. In this way, the sound carried by the exhaust stream can be damped or eliminated. Alternatively or additionally, a desired background noise can be generated. The sound generating device 16 includes, for example, a speaker.

Furthermore, there is a sound sensor 18 provided by the sound generating device 16 generated sound in combination with the exhaust gas carried sound outside the exhaust system 12 can capture. The sound sensor 18 is for example a microphone. Based on the measurements of the sound sensor 18 can the sound output of the sound generating device 16 be adapted if the measurement result of the sound sensor 18 deviates from a nominal value.

To the sound sensor 18 To protect against external influences such as rockfall or the like, is the sound sensor 18 in a housing 20 arranged, in particular in a weatherproof housing 20 ,

The housing 20 has at least one sound-permeable wall section 22 , This is the sound sensor 18 protected and yet can measure ambient sound sufficiently. In particular, a wall of the housing 20 sound-permeable. Alternatively, the housing 20 be completely made of a sound-permeable material.

The sound-permeable wall section 22 is arranged so that it comes into contact with the exhaust gas at exhaust gas flow and is thereby heated to melt if necessary, an ice layer or to prevent icing.

The housing 20 is in fluid communication with the exhaust pipe 14 , in particular, the housing interior is above a line 24 in fluid communication with the exhaust pipe 14 , The administration 24 can be rigid or flexible and has a smaller cross section than the tube 14 , preferably at least 50%.

In particular, the dimensioning of the line 28 be performed by an acoustic simulation or approximately calculated using the formula for Helmholtz resonators. The dimensioning of the line 28 takes place, for example, such that no pressure pulsations in the desired measuring range of the sound sensor between 25 Hz and 1000 Hz are introduced into the housing, since this is the measurements of the sound sensor 18 could falsify. Slower pressure fluctuations in the range below 25Hz, however, are desirable to ensure reliable operation of the actuator 26 to ensure.

Depending on the current temperature of the housing 20 or in the case 20 is an exhaust gas flow through the housing 20 through an actuator 26 , In particular a switchable actuator 26 , optionally blocked or released. As the exhaust gas usually has a high temperature, the housing becomes 20 heated by the exhaust gas flow. This has the advantage that at outside temperatures around the freezing point or below icing of the housing 20 is prevented. Consequently, it avoids the sound transmission of the case 20 is impaired by any existing snow or ice layer, which can form during a lifetime of a vehicle is melted, or the housing 20 is continuously brought to a temperature above the freezing point during driving, so that an ice layer can not even form.

For better illustration, the housing 20 with the sound sensor arranged therein 18 in the 2 and 3 shown enlarged.

The housing 20 has an outlet opening 28 depending on the current temperature and a position of the actuator 26 is flowed through or not. When the outlet opening 28 flows through, exhaust gas flows through the housing 20 and heats it up.

In 2 is the sound generation system 10 shown in a state in which the outlet opening 28 is flowed through.

In the case 20 are a first chamber 36 and a second chamber 38 formed, the first chamber 36 with the second chamber 38 via an overflow opening 40 is fluidically connectable.

The outlet opening 28 is in the second chamber 38 arranged while with the exhaust-carrying pipe 14 fluidically coupled line 24 in the first chamber 36 leads. Thus, the line 24 and the exit opening 28 separated from each other in terms of flow when the overflow 40 closed is.

In the embodiment shown, the first and second chambers are 36 . 38 through an additional intermediate wall 42 in the case 20 realized, with the overflow 40 through a recess on the intermediate wall 42 is formed.

The overflow opening 40 becomes dependent on the current temperature of the actuator 26 optionally closed or opened. For this purpose, the thermostat 30 , in particular a bimetallic strip 34 , in the area of the overflow opening 40 at the intermediate wall 42 stored. If the current temperature is above the specified limit temperature, the bimetallic strip is 34 for example, plan and covers the overflow 40 from. If the specified limit temperature is reached, the bimetal strip is 34 bent, as shown in the figures, and thereby gives the overflow 40 for an exhaust gas flow at least partially free.

That the thermostat 30 , in particular the bimetallic strip 34 at the intermediate wall 42 stored, also has the advantage that the thermostat 30 is shielded from the outside environment and thus protected from contamination and icing. This is how the sound generation system works 10 especially reliable.

A bimetal allows the thermostat 30 be realized simply and inexpensively. In addition, the thermostat 30 in addition to the function of a temperature sensor at the same time a mechanical function for releasing the flow path through the housing 20 take over. The sound generation system according to the invention can be constructed with few components.

When the overflow opening 40 is blocked, at best, over the line 24 some exhaust gas exchange with the housing 20 occur because a flow is blocked. This will prevent the case 20 and the sound sensor located therein 18 heat too much.

From the outlet 28 can optionally have a line 29 lead away to the through the housing 20 flowing exhaust gas in a certain direction.

The exhaust gas flow through the housing 20 is released, for example, below a predetermined limit temperature. The limit temperature is, for example, 5 ° C or above. To achieve this, gives the actuator 26 , especially the thermostat 30 , the inside of the housing 32 is arranged, when falling below the predetermined limit temperature, an exhaust gas flow through the housing 20 free and blocked above the specified limit temperature exhaust gas flow through the housing 20 ,

The sound-permeable wall section 22 is part of the outer wall of the first chamber in the embodiment shown 36 , This is advantageous because the sound sensor 18 also in the first chamber 36 is arranged and the sound sensor 18 thus the ambient sound, passing through the sound-permeable wall section 22 in the case 20 propagates into it, can reliably measure. In an alternative embodiment, the sound sensor 18 also in the second chamber 38 arranged and the sound-permeable wall section 22 Part of the outer wall of the second chamber 38 his.

The sound-permeable wall section 22 is at least partially flexible. Due to the flexibility, the sound-permeable wall section 22 deform so that any existing ice and / or dirt layer can be blasted off.

For example, by the exhaust gas flowing through the pipe 24 in the case 20 flows, an overpressure in the housing 20 arise, through which at least the flexible area of the sound-permeable wall section 22 bulges outward, as in 3 illustrated.

Alternatively or additionally, the housing 20 in mechanical connection with a body component and / or with a suspension of the exhaust gas pipe 14 stand. As a result, vibrations that occur during driving, to the housing 20 to get redirected. Such vibrations can also help shake off an ice and / or dirt layer.

Claims (13)

A sound generation system (10) for an exhaust system (12) of an internal combustion engine of a motor vehicle with an electrically operable sound generating device (16) for generating sound outside the vehicle interior and for optional superposition of the sound with the sound of the internal combustion engine carried by the exhaust gas flow and with a sound sensor (18) adapted to detect the sound generated by the sound generating device in combination with sound carried by the exhaust flow outside the exhaust system (12), wherein the sound sensor (18) is arranged in a housing (20) which has at least one sound-transmitting wall section (22) and which is in fluid communication with an exhaust-carrying pipe (14), and depending on the current temperature of the housing (20 ) or in the housing (20) an exhaust gas flow through the housing (20) by an actuator (26) is selectively blocked or released. Sound generation system (10) according to Claim 1 , characterized in that the housing interior (32) via a conduit (24) in fluid communication with the exhaust gas pipe (14) and the housing (20) has an outlet opening (28), in particular wherein the actuator (26) arranged and can be switched, that the outlet opening (28) is exhaust gas flowing through or not depending on the current temperature and the position of the actuator. A sound generating system (10) according to any one of the preceding claims, characterized in that an exhaust gas flow through the housing (20) is released when falling below a predetermined limit temperature. A sound generation system (10) according to any one of the preceding claims, characterized in that the actuator (26) preferably has a thermostat (30) inside the housing (32) which releases an exhaust gas flow through the housing (20) when it falls below a predetermined limit temperature and above the predetermined limit temperature blocks an exhaust gas flow through the housing (20). Sound generation system (10) according to Claim 4 , characterized in that the thermostat (30) comprises a bimetal, which deforms in dependence on the current temperature, in particular a bimetal strip 34th Sound generation system (10) according to one of Claims 4 and 5 , characterized in that the thermostat (30) mechanically closes a flow path through the housing (20) above the predetermined limit temperature. Sound generation system (10) according to one of Claims 2 to 6 characterized in that in the housing (20) a first and a second chamber (36, 38) are formed, wherein the outlet opening (28) in the second chamber (38) is arranged and wherein the second chamber (38) with the first chamber (36) via an overflow opening (40) is fluidically connectable and the overflow opening (40) depending on the current temperature of the actuator (26) is selectively closed or opened. A sound generating system (10) according to any one of the preceding claims, characterized in that the pipe (24) fluidically coupled to the exhaust gas carrying pipe (14) leads into the first chamber (36). Sound generation system (10) according to one of Claims 7 and 8th , characterized in that the sound-permeable wall portion (22) is part of the outer wall of the first chamber (36). A sound generating system (10) according to any one of the preceding claims, characterized in that the sound-permeable wall portion (22) is arranged so that it is heated at exhaust gas flow, in particular comes into contact with the exhaust gas. Sound generation system (10) according to Claim 10 , characterized in that the wall portion (22) is at least partially flexible. A sound generating system (10) according to any one of the preceding claims, characterized in that the housing (20) is in mechanical communication with a body component and / or with a suspension of the exhaust gas-carrying pipe (14). A sound generating system (10) according to any one of the preceding claims, characterized in that the housing (20) consists of a weatherproof material.

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