JP2803749B2 - Control system for engine sound in vehicle cabin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to synthesis of a sound generated mainly by an engine in a vehicle cabin, for example, a canceling sound for canceling the sound, a sound for enhancing the sound, and the like. The present invention relates to a control device that outputs a sound and controls a vehicle interior engine sound.

(Prior Art) Conventionally, as a method for controlling engine sound, the cancellation of the cavity resonance noise in the cabin is output from a speaker according to the engine speed corresponding to the operating state, thereby suppressing the muffled sound in the room. Japanese Patent Application Laid-Open No. Sho 59-9699 discloses a technique to be used.

In Japanese Unexamined Patent Publication No. 59-9699, in consideration of the occurrence of a "muffled sound" having a frequency synchronized with the engine speed,
When the engine speed is, for example, 1000 to 1500, the canceling sound is output. In this case, in fact, the noise level considerably fluctuates even at the same engine speed depending on the magnitude of the engine load, and therefore, when the engine is at or above a certain value (the intake negative pressure is at or below a certain value), it is offset. Outputs sound.

(Problems to be Solved by the Invention) However, in-vehicle sound of an actual vehicle has not only the instantaneous rotational speed of the engine, but also the frequency distribution and the volume depending on the load such as acceleration, steady rotation, or deceleration. . Therefore, as described in Japanese Unexamined Patent Application Publication No. Sho. Sho, even if the cancellation sound is output by focusing only on the level of the reference vibration of the noise, it is not enough to suppress the "muffled sound" in all the states. It is.

On the other hand, it is not advisable to consider all the sounds in the cabin as noise and only to suppress it. The sound in the cabin is then full of information on the engine operating conditions to the driver. That is, there is a case where it is necessary to actively output the synthesized sound as a means for enhancing the operational feeling of the driver. To make this possible,
It is not enough to pay attention only to the sound volume as in the above-mentioned Japanese Patent Application Laid-Open No. Sho. Sho, and it is necessary to actively output a synthesized sound whose frequency characteristic is changed according to the operating state of the engine.

Therefore, the present invention has been proposed in view of the problems of the conventional example described above, and an object of the present invention is to provide a control device capable of positively controlling the cabin engine sound in consideration of the case where the engine load fluctuates. There is a suggestion.

(Means and Actions for Achieving the Object) A configuration of the present invention for achieving the above object is a control device that controls a vehicle interior engine sound by positively outputting a predetermined synthesized sound into a vehicle interior. An engine speed detecting means for detecting an engine speed, a load detecting means for detecting an engine load and a change amount thereof, and a frequency characteristic of the predetermined synthesized sound is controlled according to the detected engine speed and load. A control unit; and a correction unit configured to correct a frequency characteristic of the predetermined synthesized sound set by the control unit in accordance with an engine load change amount detected by the load detection unit.

The control means determines the frequency characteristics of the synthesized sound according to the engine speed and the load. Here, for example, when sudden acceleration is performed, it becomes a change in the engine load and is detected by the load detecting means. Therefore, the correcting means corrects the frequency characteristics of the synthesized sound in accordance with the engine load change detected by the load detecting means.

(Embodiment) A preferred embodiment to which the present invention is applied will be described below with reference to the accompanying drawings.

FIG. 1 shows the overall configuration of the engine sound control device according to the embodiment. The control device of this embodiment uses the rotation speed of the engine 10 and the opening degree information of the accelerator 23 to estimate the state of the engine, and from the torque characteristics stored in advance based on the information, the actual engine load and the actual engine load. The response state is estimated, and accordingly, the room cancellation sound (or emphasis sound) most suitable for the driving state is generated from the signal information stored in advance and output from the speaker 21. ing. At the same time, the cancellation sound (emphasis sound) generated according to the difference between the accelerator operation amount and the actual engine speed change
By changing the sound volume and sound quality of the vehicle, the sound of change in the engine speed in response to the accelerator operation is emphasized, and the driver's feeling of accelerator operation can be enhanced.

In FIG. 1, the second-order component signal P ₁ of the ignition tool Chillon by the pulse detector 11 connexion detected engine speed signal,
The waveforms are shaped by the waveform shaping circuit 12 to become timing pulses P ₂ and P ₃ . Pulse P ₂ is fed to the transversal filter circuit 13 (Figure 3). Pulse P ₃ is sent to the controller 15, it is used to calculate the tap coefficients TP and level coefficients LV for filter circuit 13.

Here, the filter circuit 13 will be described with reference to FIG. This filter circuit is a transversal type filter circuit, and the configuration itself of this type of filter circuit is well known. It is also known that the filter circuit shown in FIG. 3 is processed by software using a DSP (Digital Signal Processing Processor). The transversal type filter is used because this type of filter is suitable for adaptive signal processing that generates an optimal synthesized sound according to the state of the engine rotation and the load. Third
In the figure, 30 denoted by Z ^-1 is k delay circuits, and each delay circuit has a function of delaying an input pulse for a predetermined time. 32, denoted by W _i (i = 1 to k), is a digital level adjuster, which is composed of k in total. Each of the adjusters 32 amplifies the binary delay signal from each delay circuit at a multiplication factor according to the tap coefficient TP and converts it into a multi-value digital signal. The tap coefficient TP is composed of k words in total so that it can correspond to the k level adjusters 32, and the data of one word of the coefficient TP indicates an amplification factor of several bits. k-1
Reference numeral 33 denotes an adder, which adds two amplified multi-level digital signals to each other. Then, as shown in the FIG. 4 (b), the composite signal from the k-1 adders have a constant phase relationship with respect to pulse P _2, a signal having a frequency of a predetermined audible range Becomes 34 is the same digital level adjuster as 32. The synthesized signal from the adder 33 is supplied to a level adjuster 34.
Is amplified as shown in FIG. 4C in accordance with the level coefficient LV. The amplified digital signal is converted by the D / A converter 31 into an analog signal X _1. This signal is power-amplified by the audio amplifier 20 (FIG. 1) and drives the speaker 11. That is, from the signal P ₂ in synchronization with the explosion of the engine has a constant phase relationship to the P ₂ (delay),
Sound having a predetermined audible frequency will flow from the speaker 21. By the way, configuring the circuit of FIG. 3 by an individual circuit causes an increase in the scale of the circuit. It is well known that the repetition delay and the amplification of digital signals are processed by software using a DSP. Therefore, it is preferable that the filter 13 be constituted by a DSP composed of a dedicated LSI.
Then, a constant phase relationship with respect to pulse P ₂ in synchronism with the engine explosion, generating a synthesized sound that has a predetermined frequency, the filter circuit 13, from the outside, and k words tap data TP It is equivalent to giving the level data LV.

The data TP and LV are generated by the correction characteristic calculation circuit 19 of the control unit 15. The control unit 15 will be described. This control unit 15
Role inputs the pulse P ₁ calculates the engine rotation speed N. On the other hand, the accelerator opening A is also input. The current engine torque is estimated from the engine speed N and the accelerator opening A, and TP and LV corresponding to the current torque are output. The TP and LV at this time are such that if the current engine torque engine sound is considered as noise, the engine sound will generate a sound opposite in phase to the sound generated in resonance with the engine sound in the cabin. If a synthetic sound that responds to the operation is to be actively created, the phase should be controlled by the TP so as to generate an in-phase synthetic sound.

The estimation of the torque is as follows. By speed calculation circuit for calculating the period of the pulse P _3, engine speed
Calculate N ₁ and N ₂ . N ₁ is sent to the load calculator 17 and the load
Used to estimate TRQ. N ₂ is the correction characteristic calculation circuit 1
Sent to 9 and used to calculate TP, LV. Control unit 15
The torque characteristic storage device 18 stores data previously measured as shown in FIG. This storage device 18 is constituted by, for example, a ROM. In the figure, 40 and 41 are torque curves with respect to the engine speed, and one torque curve is given as a set of data for a certain accelerator opening. In FIG. 2, reference numeral 40 denotes a torque curve when the accelerator opening is 100%, and 41 denotes a torque curve when the opening is 30%.
FIG. Reference numeral 42 denotes an accelerator opening parameter curve, which shows a locus curve of the maximum torque generation point with respect to the accelerator opening. There are two possible methods for estimating the current torque from a certain engine speed and accelerator opening. One method is to store one typical torque curve and a parameter curve, move this typical torque curve along the parameter curve to the current accelerator opening position, and obtain the current accelerator opening. estimating a torque curve corresponding to the current torque TRQ from the estimated torque curve and the current engine speed N ₁ Metropolitan
Is estimated. In the second method, a representative torque curve is stored for a plurality of accelerator opening data, and if the current opening is the same as the stored one, the torque curve is stored if there is no stored one. estimates the torque curve by interpolating from those stored, from the estimated torque curve and the current engine speed N ₁ Metropolitan is that estimates the current torque TRQ. For example, in FIG. 2, a broken line represents a torque curve 41 obtained when the accelerator opening is 30%. Also, if the engine speed at that time is 2500 RPM, the torque value can be estimated to be about 3.3 kg · m. The first approach is more advantageous in terms of storage capacity than the second approach, but is disadvantageous in terms of accuracy.

The tap and level coefficient storage device 22 is composed of, for example, a ROM, and stores TP and LV as maps in correspondence with the respective values of the engine speed N and the torque TRQ. That is, N, T
Using the RQ as an address, a k-word TP and a predetermined number of bits of an LV are output to the filter circuit 13.

In FIG. 1, the control unit 15 surrounded by a broken line can be easily realized by processing with software using a microcomputer. Further, as described above, the transversal filter circuit 13 can realize an audio signal processing system in which parameters can be easily changed by using a dedicated digital signal processing processor and a DA converter.

With the device of the embodiment described above, it is possible to easily obtain a correction sound that precisely corresponds to the state of the engine speed and torque.

The following modification is proposed. Accelerator opening detector 14
By differentiating the output of (1), the amount of change in the accelerator opening is obtained, and this is taken into the correction calculation in the calculation circuit 19. That is, the coefficient storage device 22 stores the coefficients TP and LV corresponding to the accelerator opening change amount, the engine speed N, and the torque TRQ. With this configuration, an effect is obtained in which the correction sound changes when the accelerator is rapidly changed, and the sense of operating the engine can be enhanced by emphasizing the accelerator operation feeling with sound. These changes can be made by changing software and parameters.

Thus, not only can the sound quality be finely controlled in accordance with the load and rotation conditions, but also the sound quality can be changed as means for enhancing the operational feeling. Adjustment of the frequency characteristics and volume change of the generated sound can be easily made by changing the stored information such as the engine characteristics and the signal processing method, and various effects can be efficiently obtained with the same device configuration.

The method of estimating the engine load is not limited to the method relying on the accelerator opening described above, but may be based on, for example, the amount of intake air to the engine or the intake pipe negative pressure.

(Effect of the Invention) As described above, the vehicle interior engine sound control device of the present invention actively outputs a predetermined synthesized sound into the vehicle interior according to the engine speed and the load, thereby providing the vehicle interior engine sound. Control. In particular, since the present invention includes the correction means, even in a transient state in which the engine load changes (for example, during rapid acceleration), a synthesized sound that reflects the amount of load change in the frequency of the synthesized sound is output. The engine sound in the vehicle compartment can be controlled according to the fluctuation of the engine load.

Compared with the conventional method of outputting a synthesized sound in consideration of only the engine speed and load, finer control of the engine sound in the vehicle compartment is possible by controlling the frequency characteristics. In particular, by changing the frequency characteristic in consideration of the amount of change in the engine torque, that is, by controlling the phase difference between the synthesized sound and the engine sound, not only can the noise be canceled out, but also the driver can respond to, for example, accelerator operation. It is possible to acoustically enhance the responsiveness of the engine (including the body).

[Brief description of the drawings]

1 is an overall configuration diagram of one embodiment to which the present invention is applied, FIG. 2 is a diagram showing characteristics of data stored in a torque characteristic storage device, FIG. 3 is a configuration diagram of a filter circuit, and FIG. FIG. 3 is a diagram illustrating a state in which a synthesized sound signal is synthesized by a filter circuit. In the figure, 10 ... engine, 11 ... ignition pulse detector,
12 ... Pulse shaping circuit, 13 ... Filter circuit, 14 ... Accelerator opening detector, 15 ... Control unit, 16 ... Rotation speed calculation circuit, 17 ... Load calculation device, 18 ... Torque characteristic storage device ,
19: Correction characteristic calculation circuit, 20: Amplifier, 21: Speaker, 22: Coefficient storage device, 23: Accelerator, 30: Delay circuit, 31: D / A converter, 32, 34: Level Moderator,
33 ... adder, 40, 41 ... torque curve, 42 ... accelerator opening degree parameter curve.

Claims (1)

(57) [Claims] A control device for controlling a vehicle interior engine sound by positively outputting a predetermined synthesized sound to a vehicle interior, comprising: an engine speed detection means for detecting an engine speed; Load detecting means for detecting, control means for controlling frequency characteristics of the predetermined synthesized sound in accordance with the detected engine speed and load, and frequency characteristics of the predetermined synthesized sound set by the control means. And a correcting means for correcting in accordance with the engine load change amount detected by the load detecting means.