The present invention relates to a sound increase apparatus which is capable of improving sound quality of an intake sound that is generated from an inlet system of internal combustion engine, and capable of increasing the intake sound over wide range of frequencies.
In recent years, there have been proposed and developed various sound increase apparatus capable of improvement of sound quality and increase of the intake sound generated from the inlet system of internal combustion engine. One such sound increase apparatus has been disclosed in Japanese Patent Provisional Publication No. 2004-218458 (hereinafter is referred to as “JP2004-218458”). In JP2004-218458, an opening is formed on a side wall of an air induction part that forms an intake flow path, and the opening and a dash panel are connected by flexible tubes. Then, the intake sound having pressure oscillations resonates with the dash panel, and the intake sound is conveyed into a vehicle cabin. And thus, a sporty intake sound can be rendered in the cabin.
In the above sound increase apparatus in JP2004-218458, however, since the air induction part communicates with the cabin via the flexible tubes, the air is taken in from about the cabin too on the intake stroke of the engine. In addition, the flexible tube connecting the air induction part and the dash panel is considerably long, so that there is a problem that a range of frequency (timbre) of the intake sound, in which the intake sound can be increased, are limited to a narrow range. And it is therefore difficult to adequately convey the intake sound over a variety of frequency ranges.
It is an object of the present invention to provide a sound increase apparatus which is capable of conveying the intake sound over wide range of frequencies without taking the air in from about the cabin and rendering a pleasant sound.
According to one aspect of the present invention, a sound increase apparatus comprises a first hollow body member that communicates with an intake flow path of an internal combustion engine; a second hollow body member that communicates with the first hollow body member; and a vibration member capable of vibrating in an out-of-plane direction, which is inserted in a connection between the first and second hollow body members and closes a cross section of the connection, and the second hollow body member has a plurality of opening portions, each of which communicates with the air.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.
Embodiments of the present invention will be explained below with reference to the drawings.
Firstly, a first embodiment will be explained below.
Here, throttle chamber 5 performs the function of increasing/decreasing the quantity of an incoming air into surge tank 2 according to the depression amount of accelerator pedal. Engine 1 is a source of vibration which generates intake pulsations in the air residing inside engine intake duct 4 with or in response to intake actions of engine 1, and then the intake pulsations become a sound source of an intake sound. These intake pulsations are pressure fluctuations or pressure oscillations which are generated in the air residing inside engine intake duct 4, and the pressure fluctuations have a plurality of fluctuation frequencies or a plurality of frequency component.
In the embodiment, sound increase apparatus 100 is connected to engine intake duct 4 between throttle chamber 5 and air cleaner 6. In more detail, sound increase apparatus 100 has a hollow pipe or tube 7 (or an intake flow path communicating pipe 7) whose one opening end portion is connected to engine intake duct 4, a diaphragm 8 that closes the other opening end portion of hollow pipe 7, and a second hollow body member 9 that is connected to hollow pipe 7 through diaphragm 8. Here, the above hollow pipe 7 is a first hollow body member.
Diaphragm 8 is a vibration or oscillation member, and is formed from elastic membrane or film etc. And diaphragm 8 vibrates or oscillates in an out-of-plane direction by or in response to inside-pressure fluctuations. As for second hollow body member 9, it has a communicating portion 20 (or a connecting pipe, or hollow pipe 20) that is a pipe connecting to hollow pipe 7 through diaphragm 8, and two branch pipes 10, 11 (or first and second outside communicating pipe 10, 11) that branch off at the other end portion of communicating portion 20. Each top end opening portions 10a, 11a of branch pipes 10, 11 is opened, and each of them forms an opening portion of second hollow body member 9. Two branch pipes 10, 11 are arranged in different extending directions from each other, but they are communicated with each other via communicating portion 20. In this embodiment, although top end opening portions 10a, 11a of branch pipes 10, 11 are placed in an engine room, directions and positions of top end opening portions 10a, 11a are different from each other.
Next, the workings and the effects of the above configuration of the sound increase apparatus will be explained. Intake pulsations generated by the source of vibration (namely, engine 1) propagate into engine intake duct 4 through intake manifold 3 and surge tank 2. The intake pulsations vibrate diaphragm 8 through hollow pipe 7, and thereby conveying the intake pulsations to downstream or lower second hollow body member 9 while preventing the air in the cabin from being taken in. When the intake pulsations are conveyed, an intake pulsation having a first resonance frequency that is formed by hollow pipe 7 and diaphragm 8 and an intake pulsation having a second resonance frequency that is formed by second hollow body member 9 and diaphragm 8 are amplified or intensified. And then, these intake pulsations are emitted or radiated from top end opening portions 10a, 11a of branch pipes 10, 11. At this time, each top end opening portions 10a, 11a of branch pipes 10, 11 is opened at different positions in the engine room, so that two acoustic or sound transfer characteristics from opening position to the cabin are different from each other. Because of this, each sound (intake pulsation) emitted from respective top end opening portions 10a, 11a is propagated into the cabin under the influence of the different sound transfer characteristics.
For instance, in the following case; one top end opening portion 10a of branch pipe 10 is placed at a position where the sounds of the two resonance frequencies or of the frequencies respectively close to the two resonance frequencies are more easily conveyed into the cabin, whereas the other top end opening portion 11a of branch pipe 11 is placed at a position where the sounds of the two resonance frequencies are not easily conveyed into the cabin but the sounds of middle frequencies between the two resonance frequencies are more easily conveyed into the cabin, pulsation sounds strengthened or intensified at around two resonance frequencies by the sound increase apparatus are efficiently propagated from top end opening portion 10a to the cabin, meanwhile, pulsation sounds of band of frequencies where resonance action is unavailable are emitted from top end opening portion 11a. Consequently, pulsation sounds of the two resonance frequencies and the middle frequency band between the two resonance frequencies are propagated into the cabin more efficiently than the other frequency band. An increase effect of intake pulsation sounds can be therefore obtained over wide range of frequencies.
As explained above, by the configuration of the sound increase apparatus, even if hollow pipe 7 and second hollow body member 9 are formed small, the increase of intake pulsation sounds not only of the two resonance frequencies but also of the middle frequency band between the two resonance frequencies can be achieved by adjustment of positions etc of top end opening portions 10a, 11a. Therefore, frequency band where the increase of sound is available does not become narrow, in other words, a sporty intake sound can be rendered in the cabin over wide range of frequencies, while preventing the air in the cabin from being taken in.
Here, in the above configuration, top end opening portions 10a, 11a of branch pipes 10, 11 are opened in the engine room. However, it is not limited to this. For example, it may be possible that either one or both of top end opening portions 10a, 11a opens at an air box (in a cowl top) positioned at an upper portion of dash panel or at the inside of a fender, and so on. In those cases, it can be possible to further efficiently propagate the intake pulsation sounds into the cabin.
Further, in the above embodiment, the number of the branch pipe that branches off is two. However, it can also be three or more branch pipes. In that case as well, a plurality of branch pipes are placed so that each position of the top end opening portions of the branch pipes is different from each other. Furthermore, The first hollow body member is formed by hollow pipe 7. However, it is not to limited to tubular-shaped hollow body member. For example, it may be ball-shaped hollow body member etc that have two opening portions. That is, the shape of the first hollow body member is not limited as long as the first hollow body member is formed by a closed space (hollow space) that has two opening portions; one is connected to engine intake duct 4, the other is connected to second hollow body member 9. With respect to second hollow body member 9, it is not limited to the tubular-shaped hollow body member, either. And this second hollow body member 9 connecting to the first hollow body member may be two or more.
Moreover, in the embodiment, the sound increase apparatus is provided at the side of engine 1 (namely, that the connecting position of the sound increase apparatus is between engine 1 and air cleaner 6). However, the sound increase apparatus may be provided between air cleaner 6 and the one end of engine intake duct 4. But, it is preferable that the connecting position is near to engine 1 which is the vibration source. In addition, for the sake of target sound or tone quality, a third opening portion (other opening portion) may be properly provided at some midpoint in an axial direction of the branch pipe.
Next, modified examples (from second embodiment to sixth embodiment) will be explained below. Firstly, a second embodiment will be explained.
A third embodiment will be explained below.
A fourth embodiment will be explained below.
A fifth embodiment will be explained below.
A sixth embodiment will be explained below.
Next, embodiments other than the above modified examples will be explained. In
As for valve 12 and controller 92, in more detail, valve 12 is formed of an open/close member 12a and an actuator 12b, and is provided inside communicating portion 20. Open/close member 12a is a member whose size can substantially cover each cross section or surface of section of branch pipes 10, 11 in communicating portion 20, and is driven by actuator 12b. Actuator 12b receives operating or driving signals from after-mentioned controller 92, then drives open/close member 12a, and thereby opens or closes the cross section of branch pipes 10, 11. In this embodiment, a stepping motor (not shown) is provided as actuator 12b, and open/close member 12a is attached to a driving shaft of the stepping motor.
Controller 92 determines which branch pipe is communicated with hollow pipe 7 (or which communicating pipeline is set) on the basis of engine rpm information that is detected by an engine rpm detection sensor (not shown). Then, controller 92 outputs the operating signals to actuator 12b based on the determination. In the shown embodiment, as the communicating pipeline, the following communicating pipelines can be set; a communicating pipeline where branch pipe 10 communicates with communicating portion 20, a communicating pipeline where branch pipe 11 communicates with communicating portion 20, and a communicating pipeline where branch pipe 10 and branch pipe 11 and communicating portion 20 are communicated with each other. And, for the above determination, a table storing a relationship between a threshold level or value of engine rpm and the communicating pipeline is provided, and controller 92 determines the setting of the communicating pipeline by using the table of the relationship. This controller 92 has CPU, RAM, and motor driver for actuator 12b, etc. besides ROM in which programs for the performance of the above function are stored. More specifically, controller 92 is built in electronic engine control unit (ECU) as a part of the function, and the engine rpm is detected at every predetermined time (for instance, every 10 msec) by a timer interrupt. Then, the operating signals for valve 12 are output in response to the change of engine rpm.
Next, the workings and the effects of the above configuration of the sound increase apparatus 100 will be explained. As shown in
Further, the intake pulsations propagated to hollow pipe 7 vibrates or oscillates diaphragm 8. Thus, the intake pulsations is conveyed to the downstream or lower communicating pipeline too through diaphragm 8. At this time, branch pipe 11 is closed with valve 12 as mentioned above. Because of this, the intake pulsations is not conveyed into branch pipe 11. And, air columns vibrate inside the communicating pipeline, then the intake sounds around resonance frequency f2 fixed by the length L2 of the air column are amplified or intensified. The amplified intake sounds are emitted or radiated from top end opening portion 10a of branch pipe 10, and further are propagated to the cabin. As described above, in the case where the engine rpm is low, the intake sounds around each resonance frequencies f1 and f2 are intensified. Here, when the intake pulsations are propagated to the communicating pipeline, the intake of air itself is prevented by diaphragm 8 and thus the air does not flow into the communicating pipeline.
Next, in a case of mid-range rpm (
Next, in a case of high engine rpm (
Here, the above resonance frequencies f1 to f4 are represented by the below expressions (1) to (4).
f1=(1/4)·(c/L1) (1)
f2=(1/4)·(c/L2) (2)
f3=(1/4)·(c/L3) (3)
f4=(1/2)·{(c/(L2+L3)} (4)
Here, c is the velocity of sound, c=331.4+0.604 t (t=Celsius degree). In the above expressions (4), the reason why (1/2) of f4 differs from the others is because the two top end opening portions of the communicating pipeline are opened.
In the shown embodiment, the lengths of hollow pipe 7 and branch pipes 10, 11 are set so that the resonance frequencies defined by the above expressions (1) to (4) are f1<f2<f4<f3. Accordingly, although as the engine rpm increases, the frequencies of intake sounds become higher, the sound increase apparatus 100 can amplify or strengthen the intake sounds of this high frequencies too in response to change of the frequency. Then, the intake sounds can be amplified over wide range of frequencies, and they can be propagated into the cabin.
On the other hand, in this embodiment, as can be seen in the graph, by changing the setting of the communicating pipeline, that is to say, by changing the branch pipe communicating with communicating portion 20 from branch pipe 10 to branch pipe 11 by means of valve 12 at a time when the engine rpm reaches an rpm corresponding to the frequency f4, the sound pressure level increases by about 20 dB. Thus, when the frequency of intake sound is high, the communicating pipeline is set to a communicating pipeline whose resonance frequency is high according to the engine rpm, and thereby keep high sound pressure level at any engine rpm as indicated by the solid lines in
Next, an eighth embodiment will be explained below with reference to a configuration in
As shown in
Next, a ninth embodiment will be explained below with reference to a configuration in
In
In the above embodiments, as previously mentioned, with respect to the shape of hollow pipe 7, it may be box-shaped hollow body member. Or hollow pipe 7 may be formed of a plurality of hollow body member. Further, it is not necessary to set the resonance frequency of hollow pipe 7 to be lowest, for instance, it may be the highest. With respect to valve 12, it can be provided not only at cross section of connection between branch pipe and communicating portion 20 but also at some midpoint of the branch pipe. Furthermore, a plurality of the valve could be provided for one branch pipe.
This application is based on a prior Japanese Patent Application No. 2005-295410 filed on Oct. 7, 2005, and a prior Japanese Patent Application No. 2005-377844 filed on Dec. 28, 2005. The entire contents of these Japanese Patent Applications Nos. 2005-295410 and 2005-377844 are hereby incorporated by reference.
Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. The scope of the invention is defined with reference to the following claims.
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2005-377844 | Dec 2005 | JP | national |
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