JP4221418B2 - Sound effect generator for vehicles - Google Patents

Description

  The present invention relates to a vehicle sound effect generating device that generates sound effects in a vehicle according to the engine rotational frequency of the vehicle.

  Conventionally, there has been proposed a sound effect generator that detects an acceleration / deceleration operation by a driver and generates a sound effect corresponding to the amount of acceleration / deceleration in a vehicle interior through a speaker in the vehicle interior (Patent Documents 1 and 2).

  In these sound effect generators, for example, when the engine speed increases in response to an acceleration operation, a loud sound effect sound is generated from the speaker at a high frequency in accordance with the increase in the engine speed, thereby producing an effect in the passenger compartment. It is increasing.

JP 54-8027 A (FIG. 1) JP-T-4-504916 (Fig. 1)

  However, in the conventional sound effect generator that generates sound effects based on the engine speed, there is no correlation between the increase / decrease of the engine speed and the actual acceleration / deceleration of the vehicle while the clutch is disengaged. . For example, when the accelerator pedal is depressed while disengaging the clutch for downshifting, the engine speed increases and the sound effect increases accordingly, but the actual speed of the vehicle itself does not change. When such a shift occurs, the driver and passengers feel uncomfortable.

  The present invention has been made in consideration of the above-described problems, and an object of the present invention is to provide a vehicle sound effect generator that can generate a natural sound effect even at the time of a shift change.

  The sound effect generator for a vehicle according to the present invention includes a waveform data table for storing waveform data for one period, frequency detection means for detecting the engine rotation frequency, and a harmonic reference signal based on the rotation frequency. A reference signal generating means for generating by sequentially reading the waveform data from the waveform data table, a control means for generating a control signal based on the reference signal, and a clutch signal indicating a clutch engagement state, Clutch signal generation means for outputting to the control means, and output means for outputting the control signal as a sound effect. Here, the control means changes the gain of the control signal according to the amount of change per unit time of the rotation frequency, and the value of the gain when the clutch is disengaged is connected to the clutch. It is set lower than the value of the gain when

  According to this invention, when the vehicle clutch is disengaged, the gain of the control signal based on the reference signal is set low. Therefore, even if the engine rotation frequency is increased for a shift change, an increase in the gain of the control signal is suppressed. Therefore, the deviation between the actual acceleration of the vehicle and the sound effect output from the output means can be reduced, and the driver and passengers can feel a sense of discomfort.

  In this invention, it is preferable that the clutch signal generating means generates the clutch signal in accordance with a depression state of a clutch pedal connected to the clutch. Thus, the clutch connection state can be determined without providing a sensor for detecting the clutch connection state in the clutch itself. For this reason, it is possible to easily determine the clutch engagement state without requiring a change in design of the clutch and its surroundings, which generally tend to be important and complicated in control.

  Here, a normal gain table having a gain value of the control signal when the clutch pedal is not depressed, and a shift change gain having a gain value of the control signal when the clutch pedal is depressed A table can also be provided.

  According to this invention, when the vehicle clutch is disengaged, the gain of the control signal based on the reference signal is set low. Therefore, even if the engine rotation frequency is increased for a shift change, an increase in the gain of the control signal is suppressed. Therefore, the deviation between the actual acceleration of the vehicle and the sound effect output from the output means can be reduced, and the driver and passengers can feel a sense of discomfort.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[1. Outline of sound effect generation mechanism]
FIG. 1 is a block diagram showing a configuration of a vehicle sound effect generating apparatus 101 according to an embodiment of the present invention.

  The vehicle sound effect generating device 101 is for a manual transmission vehicle (MT vehicle), and generates sound effects according to the rotational frequency of an engine (not shown) in the vehicle, thereby producing an effect during driving. It is something to enhance. The outline of the mechanism for generating this sound effect is as follows.

  That is, the frequency of the engine pulse Ep (engine rotation frequency fe) obtained from a sensor such as a Hall element is detected by the frequency detector 23 such as a frequency counter every time the output shaft of the engine rotates. Next, a multiplier 26 as a frequency converter generates a harmonic signal Sh that is a higher frequency signal based on the engine rotation frequency fe detected by the frequency detector 23. Next, the reference signal generation means 18 generates a reference signal Sr based on the harmonic signal Sh and the waveform data stored in the waveform data table 16. The control means 201 generates a control signal Sc1 based on the reference signal Sr, and further generates a control signal Sc2 based on the control signal Sc1. The control signal Sc2 is converted into an analog signal by a digital / analog converter (D / A converter) 22 to generate a control signal Sd. A sound effect based on the control signal Sd is output from the speaker 14. Although not shown, an output amplifier is inserted between the D / A converter 22 and the speaker 14 so that the passenger can change the gain.

  In the present embodiment, the change amount Δaf [Hz / second] of the engine rotation frequency fe per unit time is calculated by the frequency change amount detector 68. The change amount Δaf is output to the control unit 201 and used for processing when the control signal Sc1 is converted into the control signal Sc2.

  Further, in the present embodiment, the depression state of the clutch pedal 120 is detected by the clutch switch 122 connected to the clutch pedal 120, and the clutch signal Cs indicating the connection state of the clutch (not shown) is generated. The clutch signal Cs is output to the control unit 201 and used for processing when the control signal Sc1 is converted into the control signal Sc2.

  The frequency detector 23, the multiplier 26, the reference signal generation means 18, the waveform data table 16, the control means 201, and the frequency variation detector 68 are arranged on the dashboard of the vehicle, and are an ECU (electric control unit) as a comprehensive control means. ) 121 is configured.

  The speaker 14 is for letting the occupant at the occupant position 29 such as a driver's seat and a passenger seat hear sound, and the front door inner panel on both sides or the kick panel on both sides (the door of the driver's leg space). It is fixedly arranged on the inner side. In some cases, it is arranged at the lower center of the dashboard.

[2. Harmonic signal Sh (multiplier 26)]
As described above, the multiplier 26 generates the harmonic signal Sh that is a higher frequency signal based on the engine rotation frequency fe detected by the frequency detector 23. Specifically, the engine rotation frequency fe is set to the fundamental order frequency, and the harmonic signal Sh of the n-th order (for example, sixth order) frequency nfe (for example, 6fe) of the fundamental order frequency is generated. The multiple by the multiplier 26 may be an integer multiple such as 2, 3, 4, 5, 6,..., Or a real multiple such as 2.5, 3.3.

  In the present embodiment, one multiplier 26 is connected in series with the frequency detector 23. A plurality of multipliers 26 may be provided in parallel to output harmonic signals Sh of different orders (for example, 4th order, 5th order and 6th order). A configuration without the multiplier 26 is also possible.

[3. Reference signal Sr (reference signal generating means 18 and waveform data table 16)]
As described above, the reference signal generation unit 18 generates the reference signal Sr based on the harmonic signal Sh and the waveform data stored in the waveform data table 16.

  Here, the method of generating the reference signal Sr will be described. The waveform data table 16 described above is stored in a predetermined memory.

  As schematically shown in FIG. 2A and FIG. 2B, the waveform data table 16 shows each instant when the waveform for one cycle of the sine wave is equally divided by a predetermined number (N) in the time axis direction (= phase axis direction). Each instantaneous value data is stored as waveform data for each address so as to represent a value. The address (i) is an integer from 0 to N−1 (i = 0, 1, 2,..., N−1), and the alphabet A described in FIG. 2A and FIG. It is a positive real number. Accordingly, the waveform data at the address i is calculated by Asin (360 ° × i / N). In other words, a sine wave of one cycle is sampled by dividing it into N in the time direction, each sampling point is sequentially set as an address of the memory, and data obtained by quantizing the instantaneous value of the sine wave at each sampling point is used as waveform data. , Stored at the address location of the corresponding memory.

  The reference signal generation means 18 reads the waveform data from the waveform data table 16 by changing the read address cycle in accordance with the cycle of the input harmonic signal Sh, thereby obtaining a sine wave having a frequency corresponding to the harmonic signal Sh. A reference signal Sr which is a signal is generated.

  When a plurality of multipliers 26 are provided and a plurality of harmonic signals Sh having different frequencies are generated, a plurality of reference signals Sr are generated by a configuration in which a plurality of reference signal generation means 18 are provided.

[4. Control signal Sc2, change amount Δaf, and clutch signal Cs (control means 201, frequency change amount detector 68, and clutch switch 122)]
As shown in FIG. 1, the control means 201 that acoustically changes the reference signal Sr and outputs the control signal Sc2 includes a sound field adjuster 51 and a sound pressure adjuster 70 as acoustic correction means. The sound field adjuster 51 performs “sound field adjustment processing” (also referred to as “flattening processing”), “frequency enhancement processing”, and “order adjustment processing” described later. The sound pressure adjuster 70 performs “sound pressure adjustment processing” to be described later.

(1) Sound field adjustment processing (flattening processing)
In the vehicle interior, which is a sound field, there are different acoustic characteristics (also referred to as sound field characteristics, frequency transmission characteristics, or gain characteristics) for each location, and the frequency is easy to hear depending on the occupant position, for example, the driver's seat and the rear seat. There are frequencies that are difficult to hear. That is, as shown by the gain characteristic 39 in FIG. 3, it is known that there is a peak or dip in the acoustic characteristic between the speaker position and the occupant position.

  Therefore, even if the frequency of the sound effect generated from the speaker is increased linearly (linearly) in response to acceleration and the volume is increased, the sound effect is processed at the passenger's ear according to the acoustic characteristics. The feeling of linearity disappears, the feeling of breathing occurs, and the merchantability is worsening.

  A process for generating a linear feeling in the acoustic characteristics in consideration of this point is a sound field adjustment process (flattening process). This sound field adjustment processing is performed as follows using the sound field adjuster 51.

  The sound field adjuster 51 has a function as a filter, and the gain characteristic of the filter (the horizontal axis is the engine rotation frequency and the vertical axis is the gain) depends on the frequency of the reference signal Sr from the speaker 14 to the passenger position 29. Thus, the gain characteristic C00 (FIG. 4A) that changes is changed to a gain characteristic (inverted gain characteristic) Ci00 (FIG. 4B).

  The inverted gain characteristic is a characteristic that increases the output signal of the frequency that has a dip that is difficult to be transmitted acoustically, and decreases the output signal of the peak frequency that is easily transmitted acoustically. Yes, when expressed by an expression (transfer function), Ci00 = B / C00 (B is a reference value).

  Here, assuming that the gain of the sound pressure adjuster 70 is 1, that is, 0 [dB], in the vehicle sound effect generating device 101, the reference signal generating means 18 causes a constant amplitude of 30 [Hz] to 970 [Hz]. ] At the occupant position 29, the gain characteristic Ci00 for correction of the sound field adjuster 51 and the gain characteristic C00 of the sound field are multiplied at the occupant position 29 as shown in the gain characteristic C1 of FIG. 4C. Furthermore, the gain characteristic C1 is such that sound having a flat sound pressure with respect to the engine rotation frequency can be heard.

  Accordingly, when the period of the engine pulse Ep changes or is held at a constant value according to the acceleration operation, the deceleration operation, and the constant speed holding operation by the occupant, a multiple of the engine rotation frequency fe detected by the frequency detector 23. For a harmonic signal Sh having an n-order harmonic frequency nfe (for example, 6th-harmonic frequency 6fe) by the generator 26, the frequency increases, decreases, or is held at a constant frequency in substantially real time. A wave reference signal Sr is generated by the reference signal generation means 18.

  Then, as indicated by the gain characteristic 40 in FIG. 3, the reference signal Sr is converted into a control signal Sc1 corrected by the gain characteristic Ci00 of the sound field adjuster 51. If the gain of the sound pressure adjuster 70 is 0 [dB] with respect to the frequency change, so-called flat, the sound effect output from the speaker 14 at the occupant position 29 is obtained at the occupant position 29 by the vehicle interior acoustic characteristic C00. It is possible to prevent fluctuations depending on the frequency. That is, the frequency characteristics are flat at the occupant position 29. For this reason, a sound effect having a linear feeling corresponding to the state of the noise source is generated at the occupant position 29 according to the engine rotational frequency fe (in this embodiment, n times the engine rotational frequency fe). be able to.

  When the gain characteristic 40 shown in FIG. 3 is obtained, the reference signal Sr or the control signal Sc1 generates a signal whose amplitude increases in proportion to the engine rotational frequency fe in order to increase the linear feeling. ing.

  As can be seen from FIG. 3, the gain characteristic 40 after correction has a linear sound pressure level [dbA] with respect to the engine rotational frequency fe as compared to the gain characteristic 39 where there is a dip and a peak with a peak before correction. You can see that it has changed.

  As described above, the sound field adjustment process (flattening process) is a process of generating an effect sound having a linear feeling at the occupant position 29 with respect to an increase in the engine rotation frequency fe, in other words, an acceleration operation.

(2) Frequency emphasis processing The frequency emphasis processing is processing that performs a so-called equalizer function that adjusts the magnitude (gain) of a predetermined range of frequencies in the reference signal Sr. The frequency enhancement process is performed as follows.

  In the sound field adjuster 51 that performs the sound field adjustment process, for example, as indicated by a solid line in FIG. 4D, a gain characteristic Ceh that increases the gain in a predetermined frequency range, for example, a 300 [Hz] to 450 [Hz] band is obtained. By connecting the gain characteristic Ci00 in series, the combined gain characteristic Ci00eh has a frequency range of 300 [Hz] to 450 [Hz] with respect to the inversion gain characteristic Ci00 shown in FIG. 4B as shown in FIG. 4E. Is emphasized (in this example, the sound is increased), which is a characteristic Ci00eh.

  Note that the sound in the predetermined frequency range can be weakened (decreased) by configuring the occupant position 29 to have the gain characteristic Ceh ′ shown by the dotted line in FIG. 4D. When a plurality of multipliers 26 are provided as described above, frequency enhancement processing is performed on the output from each multiplier 26.

(3) Adjustment processing for each order The adjustment processing for each order is processing for adjusting the magnitude (gain) for each of a plurality of reference signals Sr having different orders. The order adjustment process can be used in a configuration in which a plurality of multipliers 26 are provided and a plurality of reference signals Sr are generated.

  By correcting each reference signal Sr according to its order, it is possible to generate a sound effect with a profound feeling that is desired to be produced at the occupant's ears present at the occupant position 29, and further improve the merchantability.

(4) Sound pressure adjustment process The sound pressure adjustment process is to adjust the sound pressure level of the sound effect output from the speaker 14 by changing the gain of the control signal Sc1. The sound pressure adjustment process according to the present embodiment is performed according to the first sound pressure adjustment process performed in accordance with the change amount Δaf [Hz / second] per unit time of the engine rotation frequency fe and the clutch connection state. A second sound pressure adjustment process is included.

(A) Sound pressure adjustment processing based on the amount of change Δaf per unit time of the engine rotation frequency fe (first sound pressure adjustment processing)
For example, as shown as the gain characteristic 72a in FIG. 5A, in the first sound pressure adjustment process, the gain Y of the control signal Sc1 is changed according to the change amount Δaf per unit time of the engine rotation frequency fe.

  The change amount Δaf is calculated by a frequency change amount detector 68 provided in the ECU 121. The frequency variation detector 68 is a difference Δf () between the frequency f1 (previous frequency) and the frequency f2 (current frequency) of the preceding and following pulses in the engine pulse Ep (FIG. 6) sequentially detected by the frequency detector 23. Δf = f2−f1), and the difference Δf is multiplied by the current frequency f2 to obtain the amount of change Δaf per unit time of the engine rotation frequency fe. Δaf = Δf × f2 [Hz / second], and Δaf is an acceleration at the engine rotation frequency fe.

  As shown in FIG. 7, it is known that the amount of change Δaf varies depending on the speed at which the transmission enters. The change amount Δaf is large on the low gear side, and the change amount Δaf is small on the high gear side.

  In general, it is preferable that the volume of the sound effect is larger with respect to the change amount Δaf on the low gear side than on the high gear side. In addition, it is preferable that the sound effect is small during cruise traveling or deceleration where the vehicle speed is automatically maintained constant. Furthermore, it is preferable to reduce the sound effect so as not to cause an unpleasant sound at the time of flying or kicking down exceeding the change amount Δaf corresponding to the first speed full open acceleration.

  The gain characteristics 72a and 72b in FIG. 5A indicate weighting gain characteristics that are acoustic correction characteristics set in the sound pressure adjuster 70 based on such consideration.

  The gain characteristic 72a indicates the gain characteristic in the normal mode (clutch engagement mode). The normal mode is a mode in a state where a clutch (not shown) is engaged. The gain characteristic 72b indicates the gain characteristic in the shift change mode (clutch disengagement mode). The shift change mode is a mode when the clutch is disengaged. Details of the gain characteristic 72b will be described later.

  In the normal mode gain characteristic 72a (FIG. 5A), the weighting gain Y in the first speed full open frequency change amount X2 (FIG. 7) is maximized (for example, 0 [dB]), and the change amount Δaf from the first speed full open frequency change amount X2. As the value becomes smaller, the weighting gain Y is gradually reduced to the fourth speed full open frequency change amount X1 (FIG. 7). That is, a large sound effect is obtained when accelerating on the low gear side, and a small sound effect is obtained when accelerating on the high gear side. Further, when the amount of change Δaf per unit time of the engine rotation frequency fe, such as during cruise traveling or deceleration, is near zero, the weighting gain Y is set to the minimum (for example, −15 [dB]). Further, in the empty range (including the time of kickdown) exceeding the first-speed full-open frequency change amount X2, the weighting gain characteristic 72a1 that decreases the weighting gain Y suddenly so as not to generate an unpleasant sound or the weighting gain Y The weighting gain characteristic 72a2 that does not change can be selected. Normally, the weighting gain characteristic 72a1 is selected.

(B) Sound pressure adjustment processing based on clutch engagement state (second sound pressure adjustment processing)
In the second sound pressure adjustment process, the gain of the control signal Sc1 is changed according to the engagement state of the clutch. That is, the normal mode gain characteristic 72a and the shift change mode gain characteristic 72b shown in FIG. 5A are switched in accordance with the engagement state of the clutch. As shown in FIG. 8, the gain characteristics 72 a and 72 b are switched by the clutch signal Cs from the clutch switch 122.

  As shown in FIG. 5A, the gain characteristic 72b in the shift change mode also shows the same waveform as the gain characteristic 72a, but the gain change width is set smaller than that of the gain characteristic 72a. For example, the gain Y of the first-speed full-open frequency change amount X2 (FIG. 7) that maximizes the weighting gain Y is set to, for example, -5 [dB], and the change amount Δaf per unit time of the engine rotation frequency fe is near zero. For example, the weighting gain Y is -15 [dB].

  The gain characteristic data is written in advance in a memory (not shown) such as an EEPROM.

  Next, details of a method for switching between the gain characteristic 72a and the gain characteristic 72b in accordance with the engagement state of the clutch will be described.

  The sound pressure adjuster 70 (control unit 201) determines the clutch engagement state based on the presence or absence of the clutch signal Cs from the clutch switch 122. As shown in FIG. 1, the clutch signal Cs is generated by a clutch switch 122 connected to the clutch pedal 120.

  The clutch switch 122 employs a normally closed switch in which one end of a fixed terminal is grounded and the other end is connected to a power supply of +12 [V] through a resistor 124. For this reason, as shown in FIG. 9, while the driver is stepping on the clutch pedal 120, in other words, while the clutch (not shown) is disengaged, the movable contact is separated from the closed state to the open state. The clutch signal Cs of +12 [V] is supplied to the sound pressure adjuster 70 constituting the control means 201. Therefore, the control means 201 can recognize that the clutch is disengaged when the clutch signal Cs of +12 [V] is supplied.

  Even when the driver is stepping on the clutch pedal 120, a state where the driving force from the engine is completely transmitted to the driving wheels due to the play of the clutch pedal 120, or a part of the driving force from the engine is Strictly speaking, the state transmitted to the drive wheels (so-called half-clutch state) cannot be said to be disengaged. However, the time during which these states continue during a shift change is short, and the feature of lowering the sound effect gain when the clutch is disengaged, which is a feature of the present invention, is hardly impaired. Therefore, in the present invention, these states can be included in the state where the clutch is disengaged. As will be described later, the gain can be adjusted by discriminating these states.

  FIG. 10 shows a flowchart for the sound pressure adjuster 70 (control unit 201) to determine the clutch engagement state.

  In step S1, when a battery (not shown) is connected to the ECU 121, the sound pressure regulator 70 detects the clutch signal Cs, and whether there is the clutch signal Cs, that is, the output from the clutch switch 122 is the threshold voltage. It is determined whether the voltage exceeds 10 [V]. When the output from the clutch switch 122 is 10 [V] or less, in step S2, the sound pressure adjuster 70 enters the normal mode (clutch engagement mode), and the first sound pressure adjustment process is performed using the gain characteristic 72a of FIG. 5A. Do. After step S2, the process returns to step S1. When the output from the clutch switch 122 exceeds 10 [V] in step S1, the sound pressure adjuster 70 enters the shift change mode (clutch disengagement mode) in step S3, and the first sound is obtained using the gain characteristic 72b of FIG. 5A. Perform pressure adjustment processing. After step S3, the process returns to step S1. These steps S1 to S3 are repeated until the vehicle engine is stopped.

  The gain characteristics 72a ′ and 72b ′ shown in FIG. 5B are the same as the gain characteristics 72a and 72b, respectively. However, the gain characteristic 72b ′ has a change amount Δ per unit time of the engine rotation frequency fe that is a first-speed full-open frequency change amount. The value of the gain Y when exceeding X2 is set larger than the value of the gain Y of the gain characteristic 72a ′. As a result, when the driver deliberately performs the idling, it is possible to avoid a rapid decrease in gain and to prevent the sound effect from feeling uncomfortable.

(C) Effect of Sound Pressure Adjustment Processing FIG. 11A shows data with the engine rotation frequency fe when the transmission is shift-changed from the second speed to the third speed on the vertical axis and the time t [second] on the horizontal axis. It is shown. In FIG. 11B (before and after the countermeasure for the p-order high frequency), FIG. 11C (before and after the countermeasure for the q-order high frequency), and FIG. The sound pressure [dB] is shown when the vehicle sound effect generator according to the embodiment of the present invention is used and when it is not used.

  As can be seen from FIGS. 11A to 11D, while the clutch signal Cs is being output, the sound pressure of the output Fr from the speaker is lower when the vehicle sound effect generator is used than when the vehicle sound effect generator is not used. It has become. For this reason, by implementing this invention, the deviation between the actual acceleration of the vehicle and the sound effect output from the speaker can be reduced, and the driver and passengers feel uncomfortable with the sound effect. It can be said that it is possible.

[5. Effects in this embodiment]
As described above, according to the embodiment described above, the vehicle sound effect generating apparatus 101 includes the waveform data table 16 that stores the waveform data for one cycle, the frequency detector 23 that detects the engine rotation frequency fe, Control for generating a reference signal Sr for harmonics based on the engine rotation frequency fe by sequentially reading the waveform data from the waveform data table 16 and a control signal Sc2 based on the reference signal Sr. Means 201, a clutch switch 122 that generates a clutch signal Cs indicating a clutch connection state and outputs the clutch signal Cs to the control means 201, and a speaker 14 that outputs the control signal Sc2 as a sound effect. Here, the control means 201 changes the gain of the control signal Sc2 according to the amount of change Δaf per unit time of the engine rotation frequency fe, and sets the gain value when the clutch is disengaged when the clutch is engaged. Set lower than the gain value.

  For this reason, when the clutch of the vehicle is disengaged, the gain of the control signal Sc2 based on the reference signal Sr is set low. Therefore, even if the engine rotation frequency fe is increased for a shift change, an increase in the gain of the control signal Sc2 is suppressed. Therefore, the deviation between the actual acceleration of the vehicle and the sound effect output from the speaker 14 can be reduced, and the driver or passenger can feel a sense of discomfort.

  In the above embodiment, the clutch engagement state can be determined according to the depression state of the clutch pedal 120 connected to the clutch. Thus, the clutch connection state can be determined without providing a sensor for detecting the clutch connection state in the clutch itself. For this reason, it is possible to easily determine the clutch engagement state without requiring a change in design of the clutch and its surroundings, which generally tend to be important and complicated in control.

[6. Application of the present invention]
Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the description in this specification.

  In the above embodiment, the clutch connection state is determined using the clutch switch 122 connected to the clutch pedal 120, but the present invention is not limited to this as long as the clutch connection state can be determined. For example, the clutch engagement state can also be determined by detecting a control signal to a clutch pressure lever that moves the clutch disk forward and backward with respect to the engine-side flywheel. Further, the clutch is not limited to a general so-called dry type single clutch, and there is no correlation between the amount of change Δaf per unit time of the engine rotation frequency fe and the actual acceleration of the vehicle while the clutch is disengaged. Any clutch may be used.

  Moreover, in the said embodiment, the clutch switch 122 was made into the on-off type, and it was supposed to determine two states, the state in which the clutch is connected, and the state in which the clutch is disengaged. However, for example, by changing the output of the clutch switch 122 according to the depression amount of the clutch pedal 120, three or more states can be determined. The three or more states include, for example, a state in which the driving force from the engine is completely transmitted to the driving wheels, a state in which a part of the driving force from the engine is transmitted to the driving wheels (a so-called half clutch) And a state in which the driving force from the engine is not transmitted to the driving wheels at all. In this case, a plurality of modes and gain tables may be set according to these states.

  Further, the clutch switch 122 is kept on-off type, and the clutch connection state is determined by using the numerical values of the speedometer that measures the speed of the vehicle and the accelerometer that measures the acceleration of the vehicle. It is also possible to adjust the degree to which the gain of the control signal Sc2 is lowered.

  In the above embodiment, the normal gain table 81 having the gain value of the control signal Sc2 when the clutch pedal 120 is not depressed, and the shift having the gain value of the control signal Sc2 when the clutch pedal 120 is depressed. A change gain table 82 is provided. However, the present invention is not limited to this as long as the gain value of the control signal Sc2 when the clutch is disengaged can be set lower than the value of the control signal Sc2 when the clutch is engaged. For example, a normal gain table 81 having a gain value of the control signal Sc2 when the clutch pedal 120 is not depressed is provided, and when the clutch pedal 120 is depressed, the gain value of the control signal Sc2 in the normal gain table 81 is provided. It is also possible to adopt a configuration in which is multiplied by a coefficient P (0 <P <1).

  In the above embodiment, the sound field adjuster 51 performs the sound field adjustment process, the frequency emphasis process, and the order adjustment process before the first and second sound pressure adjustment processes. Accordingly, the sound field adjustment process, the frequency enhancement process, and the order adjustment process may not be performed.

  In the above embodiment, the clutch signal Cs is output when the clutch pedal 120 is depressed. However, the clutch signal Cs is not limited to this as long as it indicates the engaged state of the clutch. For example, the clutch signal Cs may be output when the clutch pedal 120 is not depressed, and the clutch signal Cs may not be output when the clutch pedal 120 is depressed. Further, a configuration in which the voltage value of the clutch signal Cs is changed in proportion to the depression amount of the clutch pedal 120 is also possible.

FIG. 1 is a block diagram showing a configuration of a vehicle sound effect generator according to an embodiment of the present invention. FIG. 2A is an explanatory diagram showing the contents of the waveform data memory. FIG. 2B is an explanatory diagram showing a sine wave generated with reference to the waveform data memory. FIG. 3 shows the frequency characteristics of the sound pressure level before and after the sound field adjustment processing is performed. FIG. 4A is a gain characteristic diagram measured at the occupant position. FIG. 4B is a gain characteristic diagram obtained by inverting the gain characteristic of FIG. 4A. FIG. 4C is a gain characteristic diagram obtained by synthesizing the gain characteristics of FIGS. 4A and 4B. FIG. 4D is a gain characteristic diagram that emphasizes a predetermined frequency range. FIG. 4E is an inversion gain characteristic diagram in which a predetermined frequency range is emphasized. 5A and 5B are diagrams showing weighting gain characteristics according to the clutch engagement state. FIG. 6 is a waveform diagram of an engine pulse. FIG. 7 is a shift characteristic diagram of the MT vehicle. FIG. 8 is a diagram simply illustrating a method of switching between two weighting gain tables in accordance with the clutch connection state. FIG. 9 is a diagram illustrating the output of a clutch signal indicating the clutch engagement state and the vehicle speed corresponding to the clutch signal output. FIG. 10 is a flowchart for determining the clutch engagement state. FIG. 11A is a diagram illustrating an engine rotation frequency when the transmission is shift-changed from the second speed to the third speed. FIG. 11B to FIG. 11D are diagrams showing sound pressure levels of outputs from the speakers when the vehicle sound effect generating device according to one embodiment of the present invention is used and when not used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 ... Speaker (output means) 16 ... Waveform data table 18 ... Reference signal generation means 23 ... Frequency detector 68 ... Frequency change detector 70 ... Sound pressure adjuster 81 ... Normal gain table 82 ... Shift change gain table 101 ... Vehicle sound effect generator 120 ... Clutch pedal 122 ... Clutch switch (clutch signal generating means)
201 ... control means Cs ... clutch signal fe ... engine rotation frequency Sc1, Sc2 ... control signal Sr ... reference signal Δaf ... change amount per unit time of engine rotation frequency

Claims (3)

A waveform data table for storing waveform data for one period;
Frequency detection means for detecting the rotational frequency of the engine;
A reference signal generating means for generating a harmonic reference signal based on the rotation frequency by sequentially reading the waveform data from the waveform data table;
Control means for generating a control signal based on the reference signal;
Clutch signal generating means for generating a clutch signal indicating a clutch connection state and outputting the clutch signal to the control means;
An output means for outputting the control signal as a sound effect, a vehicle sound effect generator,
The control means includes
Changing the gain of the control signal according to the amount of change per unit time of the rotational frequency, and
In order to reduce the uncomfortable feeling of the driver and passengers due to the difference between the acceleration of the vehicle and the sound effect, the gain value when the clutch is disengaged is the gain value when the clutch is engaged. A sound effect generator for a vehicle characterized by being set lower than the above. A sound effect generator for a vehicle according to claim 1,
The vehicle sound effect generating device, wherein the clutch signal generating unit generates the clutch signal in accordance with a depression state of a clutch pedal connected to the clutch. A sound effect generator for a vehicle according to claim 2,
A normal gain table having a gain value of the control signal when the clutch pedal is not depressed, and a shift change gain table having a gain value of the control signal when the clutch pedal is depressed. A vehicle sound effect generator comprising: a vehicle sound effect generator;

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