WO2011148245A1

WO2011148245A1 - Vehicle warning sound emitting apparatus

Info

Publication number: WO2011148245A1
Application number: PCT/IB2011/001102
Authority: WO
Inventors: Yuki Nakajima; Takaya Inukai; Keisuke Suzuki; Naoki Ueda
Original assignee: Nissan Motor Co., Ltd.
Priority date: 2010-05-24
Filing date: 2011-05-23
Publication date: 2011-12-01
Also published as: JP2011245908A; JP5560902B2

Abstract

A vehicle warning sound emitting apparatus comprises a warning sound emitting component (2) and a controller (1). The warning sound emitting component (2) is configured to selectively emit a warning sound that is audible outside of the vehicle (3). The controller (11) is configured to control the warning sound emitting component (2) to emit the warning sound to convey vehicle information to a person in a surrounding area outside the vehicle (3) while a prescribed warning sound emission condition is satisfied. The controller (11) is further configured to change an operating state of an engine (4) of the vehicle (3) such that an engine sound emitted by the engine (4) while the warning sound emission is satisfied is louder than the engine sound that is emitted by the engine (4) when the warning sound emission condition is not satisfied.

Description

VEHICLE WARNING SOUND EMITTING APPARATUS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2010- 118519, filed on May 24, 2010. The entire disclosure of Japanese Patent Application No. 2010-1 18519 is hereby incorporated herein by reference.

BACKGROUND

Field of the Invention

[0002] The present invention relates to a vehicle warning sound emitting apparatus. More particularly, the present invention relates to a vehicle warning sound emitting apparatus that emits sounds pertaining to conditions of the electric vehicle.

Background Information

[0003] Certain vehicles can be constructed to operate very quietly. For example, certain vehicles that are equipped with an internal combustion engine can be configured to operate and move more quietly than conventional combustion engine vehicles. Electric vehicles that are propelled by an electric motor in an electric drive mode (EV mode) can also operate quietly. Furthermore, a parallel hybrid vehicle can operate in an EV mode during which the vehicle is propelled by power from an electric motor, and in a hybrid mode (HEV mode) during which the vehicle is propelled by power from both a combustion engine and the electric motor. Also, in a series hybrid vehicle, a combustion engine is used to generate electric power, and the generated electric power can drive an electric motor that is used to propel the vehicle. The parallel and series hybrid vehicles thus can also operate more quietly than conventional vehicles.

[0004] Since each of these types of vehicles has a quiet operating sound, a quiet moving sound, or both, these quieter vehicles may not be as readily detectable by pedestrians as are typical combustion engine vehicles. For example, the gear shifting operations, forward and reverse movement, vehicle speed and other travelling or operating conditions of such vehicles may be quieter than in typical combustion engine vehicles. Therefore, these types of vehicles may be equipped with a warning device that emits sound externally of the vehicle when the vehicle is traveling, for example, at a low speed in an urban environment in which many people may be present in a surrounding area outside the vehicle.

[0005] For example, Japanese Laid-open Patent Publication No. 07-322403 describes a warning sound emitting apparatus that operates to emit a warning sound toward a person in a surrounding area outside of a vehicle. The warning sound emitting apparatus can include, for example, a speaker, a buzzer or any other warning sound emitting source that can emit a warning sound to a person in a surrounding area outside of the vehicle when a prescribed condition occurs requiring that a warning sound be emitted.

SUMMARY

[0006] As discussed above, a series hybrid vehicle or a parallel hybrid vehicle can travel using energy from both an engine and an electric motor. Although driving situations exist in which it may be necessary to run the engine of a hybrid vehicle at a high speed or with large torque, a hybrid vehicle is basically intended to run quietly and be environmentally friendly. Therefore, the engine of a hybrid vehicle is often operated in as quiet an operating region as possible in view of exhaust gas, noise and vibration issues. Also, improvements can be made to the manner in which a warning sound emitting apparatus can be used in a hybrid vehicle.

[0007] A prescribed condition under which a warning sound should be emitted, which can also be referred to as warning sound emission condition, can be a situation in which it is necessary or desirable to issue a warning to convey vehicle information. While the warning sound emission condition is satisfied, the warning should be reliably conveyed to a person in a surrounding area outside the vehicle. Also, if the engine is running while the warning sound emission is satisfied, then a person in a surrounding area outside the vehicle can obtain vehicle information from both the warning sound and the engine sound.

[0008] However, in a hybrid vehicle, the engine is often operated at as quiet an operating point as possible in consideration of exhaust emissions, as well as noise and vibration issues, as explained previously. Consequently, since the engine is usually operated as quietly as possible when a warning sound emission condition is satisfied, a person in a surrounding area outside the vehicle may be unable to readily obtain vehicle information from the engine sound. [0009] Accordingly, a warning sound emitting apparatus can be controlled to refrain from emitting a warning sound when the engine is running and generating an engine sound that is sufficient to serve as a warning sound for conveying vehicle information. That is, the warning sound emitting apparatus can be switch into a non-operating state during which the warning sound emitting apparatus does not emit a warning sound. However, with such a control scheme, it is possible that a warning sound inadvertently may not be emitted even though a warning sound emission condition is satisfied.

[0010] Also, in a hybrid vehicle, a quiet engine operating condition can correspond to an operating condition at which the rotational speed of the engine is low and quiet operation can be ensured. However, at such an operating condition, the fuel efficiency of the vehicle may be lower than an optimum fuel efficiency corresponding to a best possible fuel consumption rate. Conversely, when the vehicle is running at an optimum fuel efficiency operating rate, the engine speed generally will be higher than the engine speed at the quiet operating rate. Therefore, the engine sound generally will be louder than the engine sound emitted at the quiet operating rate.

[0011] Thus, when a warning sound emission is satisfied, vehicle information can be reliably conveyed to a person in a surrounding area outside a vehicle using the engine sound. This can be accomplished, for example, by increasing the rotational speed of the engine to change the engine operating state from a quiet engine operating rate to another operating rate having an increased engine sound. As the engine operating rate moves from the quiet operating rate and approaches the optimum fuel efficiency operating rate, the fuel efficiency of the engine improves in comparison with when the engine operates at the quiet operating rate.

[0012] Accordingly, in view of the state of the known technology, a vehicle warning sound emitting apparatus basically comprises a warning sound emitting component and a controller. The warning sound emitting component is configured to selectively emit a warning sound that is audible outside of the vehicle. The controller is configured to control the warning sound emitting component to emit the warning sound to convey vehicle information to a person in a surrounding area outside the vehicle while a prescribed warning sound emission condition is satisfied. The controller is further configured to change an operating state of an engine of the vehicle such that an engine sound emitted by the engine while the warning sound emission is satisfied is louder than the engine sound that is emitted by the engine when the warning sound emission condition is not satisfied.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Referring now to the attached drawings which form a part of this original disclosure:

[0014] Figure 1 is a control system diagram diagrammatically illustrating a vehicle warning sound emitting apparatus according to a disclosed embodiment;

[0015] Figure 2 is a flowchart showing an example of a warning sound control program executed by a warning sound controller shown in Figure 1 ;

[0016] Figure 3A is an engine performance graph illustrating an exemplary relationship between electric power that should be generated by an engine of the vehicle shown in Figure 1 and a quiet operation curve for the engine when the warning sound control program shown in Figure 2 is executed by the warning sound controller;

[0017] Figure 3B is a graph illustrating an exemplary change characteristic of an amount of supplemental engine speed by which the engine rotational speed is increased during an engine operating state change in relation to vehicle speed when the warning sound control program shown in Figure 2 is executed by the warning sound controller;

[0018] Figure 3C is a graph illustrating an exemplary change characteristic of an amount of supplemental generated electric power by which generated electric power increases when the engine rotational speed increases when the warning sound control program shown in Figure 2 is executed by the warning sound controller;

[0019] Figure 4 is an exemplary operation time chart for the warning sound control program shown in Figure 2, with section (a) of the time chart corresponding to a situation in which the vehicle is accelerated from a stopped state without the engine being started and section (b) of the time chart corresponding to a situation in which the vehicle is decelerated to a stop without the engine being stopped;

[0020] Figure 5 is an exemplary operation time chart for the warning sound control program shown in Figure 2, with section (a) of the time chart corresponding to a situation in which the vehicle is accelerated from a stopped state in a manner that involves the engine being started, and section (b) of the time chart corresponding to a situation in which the vehicle is decelerated to a stop in a manner that involves the engine being stopped;

[0021] Figure 6A is a characteristic diagram indicating an example of how a prescribed amount of time during which an on-to-off transition of the vehicle exterior speaker shown in Figure 2 is delayed is varied; and

[0022] Figure 6B is a characteristic diagram indicating an example of how a prescribed amount of time during which an engine stoppage is delayed is varied.

DETAILED DESCRIPTION OF EMBODIMENTS

[0023] Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0024] Referring initially to Figure 1 , a vehicle warning sound emitting apparatus 1 is illustrated according to a disclosed embodiment. More specifically, Figure 1 is a control system diagram showing an example of components of a control system of the vehicle warning sound emitting apparatus 1 for controlling a vehicle exterior speaker 2 that can serve as a warning sound emitting source.

[0025] In this embodiment, the vehicle 3 in which the warning sound emitting apparatus 1 is employed is a series hybrid vehicle which, as understood in the art, is an electric powered vehicle equipped with an electric power generator. The vehicle 3 includes an engine 4 that is configured to drive an electric generator (not shown), a battery (not shown) that is configured to store electric power generated by the electric generator, and an electric motor 5 that is driven by electric power from the battery and functions as a propulsion power source to propel the vehicle 3.

[0026] However, it is also acceptable for the vehicle 3 to be a parallel hybrid vehicle in which the engine 4 is not used to generate electricity but can also be used in tandem with the electric motor 5 as a propulsion power source to propel the vehicle 3. As understood in the art, such a parallel hybrid vehicle is configured to switch between an electric drive mode (EV mode) in which the vehicle 3 is driven by the electric motor 5 and a hybrid mode (HEV mode) in which the vehicle 3 is driven with power from both the engine 4 and the electric motor 5. Naturally, the vehicle 3 can be a car, truck, van, SUV or any other suitable type of vehicle. Also, the vehicle 3 need not be a hybrid vehicle or an electric powered vehicle, but rather, can be a conventional combustion engine vehicle or a vehicle having any combination of a combustion engine and electronic motor.

[0027] When, as in this embodiment, the vehicle 3 employing the warning sound emitting apparatus 1 is a series parallel vehicle as described above, the engine 4 is generally stopped when the battery is in a state that does not require recharging or does not permit recharging. Conversely, the engine 4 is generally operated when the battery is in a state in which recharging is necessary or desirable and conditions enable recharging of the battery to be possible.

[0028] In this example, an engine operation control system 6 controls the engine 4 in a manner as understood in the art. Also, in this example, a motor propulsion control system 7 controls the electric motor in a manner as understood in the art. The control systems 6 and 7 are both assumed to be in an on-state while an ignition switch 8 operated by, for example, a driver is turned on.

[0029] While the motor propulsion control system 7 is in an on-state, the motor propulsion control system 7 drives the electric motor 5 to propel the vehicle when an operating condition of the electric motor 5 is satisfied. More specifically, when a brake pedal (not shown) is released and an accelerator pedal (not shown) is depressed, the motor propulsion control system 7 drives the electric motor 5 in a rotational direction

corresponding to a driving operation performed the driver and with a torque corresponding to the driving operation. The motor torque is transmitted to one or more wheels 9 of the vehicle 3 by, for example, a drive mechanism or any other suitable mechanism known in the art, to propel the vehicle 3.

[0030] While the engine operation control system 6 is in an on-state, the engine operation control system 6 determines if the battery is in a state that does not require or permit recharging. The engine operation control system 6 also determines if the battery is in a state in which recharging is necessary or desirable and conditions enable recharging of the battery to be possible. The engine operation control system 6 then stops the engine 4 if the battery is in a state that does not require or permit recharging. Conversely, the engine operation control system 6 operates the engine 4 if the battery is in a state in which recharging is necessary or desirable and conditions are such that recharging of the battery is possible.

[0031] As further shown in Figure 1 and described herein, the vehicle exterior speaker 2 operates as a warning sound emitting component configured to selectively emit a warning sound that is audible outside of the vehicle 3. The vehicle exterior speaker 2 is controlled by a warning sound controller 11. The warning sound controller 1 1 receives a signal from a range sensor 12 that operates to detect if a shift mechanism is set to Park (P), Reverse (R), Neutral (N), or Drive (D) in response to a shifting operation performed by a driver in order to park the vehicle 3 or designate a movement direction for the vehicle 3.

[0032] The warning sound controller 11 also receives a signal from a vehicle speed sensor 13 that operates to detect a vehicle speed VSP. The warning sound controller 1 1 further receives a signal from a brake switch 14 that turns on when the brake pedal is depressed and a braking state exists, and turns off when the brake pedal is released and a non-braking state exists. In addition, the warning sound controller 1 1 receives a signal from a warning sound controller switch 15 that can be operated by, for example, a driver. The warning sound controller switch 15 can be set to a first condition to instruct the warning sound controller 11 to execute on-off control with respect to the vehicle exterior speaker 2, or to a second condition to instruct the warning sound controller 1 1 to maintain the vehicle exterior speaker 2 in a non-operating state so that a warning sound is not emitted. Furthermore, the warning sound controller 1 1 receives a signal from the ignition switch 8 that, for example, indicates that the engine operation control system 6 and the motor propulsion control system 7 have been turned on.

[0033] It should also be noted that the engine operation control system 6, the motor propulsion control system 7, and warning sound controller 11 shown in Figure 1 can each include, for example, a microcomputer with a control program that controls and interacts with the components of the vehicle 3 as discussed herein. The engine operation control system 6, the motor propulsion control system 7, the warning sound controller 11 , and any other controller discussed herein can also each include other conventional components such as an input interface circuit, an output interface circuit, and storage devices such as a ROM (Read Only Memory) device and a RAM (Random Access Memory) device. The RAM and ROM store processing results and control programs that are run by the engine operation control system 6, the motor propulsion control system 7, and warning sound controller 11. The engine operation control system 6, the motor propulsion control system 7, and warning sound controller 11 and any other controller discussed herein are operatively coupled to the components of the vehicle 3 in a conventional manner. It will be apparent to those skilled in the art from this disclosure that the precise structure and algorithms for the engine operation control system 6, the motor propulsion control system 7, and warning sound controller 1 1 and any other controller discussed herein can be any combination of hardware and software that will carry out the functions of the

embodiments discussed herein.

[0034] As will now be described, the warning sound controller 11 executes a control program as shown, for example, in Figure 2 repeatedly once every prescribed time period, such as every 10 msec or at any other suitable interval, with a regular interrupt while the ignition switch 8 is in an on-state. The program serves to operate the warning sound controller 1 1 to control emission of a warning via, for example, the vehicle exterior speaker 2 that can be received by a person existing in a surrounding area outside the vehicle 3. The warning can convey vehicle information indicating, for example, the existence of the vehicle 3, as well as a shift operation, a brake operation, or other operation indicating an intent of a driver. The warming can also convey information pertaining to, for example, the travel direction of the vehicle 3, as well as vehicle speed and other traveling conditions.

[0035] Turning now to Figure 2, in step S 11 , the warning sound controller 11 determines if the warning controller switch 15 is on or off to determine if the driver desires the warning sound controller 11 to execute on-off control of the vehicle exterior speaker 2. If the warning sound controller switch 15 is not on, then the driver does not wish for the vehicle exterior speaker 2 to emit a warning sound. For example, the driver may not want for the vehicle to emit a warning sound because the driver is driving in a residential area. Thus, processing performed by the warning sound controller 1 1 proceeds to steps S31, SI 2, S13 and SI 4 as indicated.

[0036] In step S31, the warning sound controller 1 1 sets an engine operating state change command to 0, so that the engine operating state change command is not issued to the engine operation control system 6. When the engine operation control system 6 does not receive the engine operating state change command from the warning sound controller 11 , the engine operation control system 6 executes normal engine control of the engine 4 as will now be explained.

[0037] As shown in Figure 3, the single-dot chain line curves are constant generated power curves representing engine torque Te versus engine rotational speed Ne that produce a generated electric power in accordance with battery charge states. In this example, two generated power values Pwl and Pw2 are shown. The solid line-curve is a plot representing engine torque Te versus engine speed Ne that results in the quietest operation while producing a particular generated electric power value.

[0038] If the generated electric power is, for example, Pwl, then the engine operation control system 6 sets the engine operating point to an engine speed Nel and an engine torque Tel corresponding to an intersection point Al of the constant generated power curve for Pwl and the quiet operation curve. Thus, the engine operation control system 6 controls the engine 4 to operate quietly at the point Al . Similarly, if the generated electric power is Pw2, then the engine operation control system 6 sets the engine operating point an intersection point A2 of the constant generated power curve for Pw2 and the quiet operation curve. Thus, the engine operation control system 6 controls the engine to operate quietly at the point A2.

[0039] As discussed above, a quiet engine operating point is an operating point at which the rotational speed of the engine is low and quiet operation can be ensured.

However, the fuel efficiency is typically less than an optimum fuel efficiency

corresponding to a best possible fuel consumption rate. Conversely, when running at an optimum fuel efficiency operating point, the engine speed will be higher than the engine speed of the quiet operating point. Therefore, the engine sound will be louder than the engine sound emitted at the quiet operating point. Thus, as shown in Figure 3 A and discussed below, if the engine rotational speed is increased from a quiet engine operating point, then the engine sound will increase and a person in a surrounding area outside the vehicle can obtain vehicle information readily from the increased engine sound.

Additionally, the engine operating point will move closer to an optimum fuel efficiency operating point so that the fuel efficiency is improved. [0040] The processing then continues from step S31 to step Si 2. In step SI 2, an engine-off timer TENGOFF used for the on-off control of the vehicle exterior speaker 2 is reset to 0. That is, the engine-off timer TENGOFF is used to measure an amount of time elapsed since an engine stop request occurred with respect to the engine 4.

[0041] In step SI 3, an engine on timer TENGON used for the on-off control of the vehicle exterior speaker 2 is reset to an upper limit value. The engine on timer TENGON is reset to 0 when the engine 4 is started and serves to measure an amount of time elapsed since the engine 4 was last started. In step SI 4, the warning sound controller 1 1 turns the vehicle exterior speaker 2 off to prohibit emission of a warning sound, thereby complying with the driver's desire that a warning sound not be emitted from the vehicle exterior speaker 2.

[0042] On the contrary, if the warning sound controller 1 1 determines in step S 11 that the driver has turned the warning sound controller switch 15 on and thus desires for a warning sound to be emitted from the vehicle exterior speaker 2, then the processing continues to step SI 5. Accordingly, on-off control of the vehicle exterior speaker 2 is performed as will now be explained.

[0043] That is, the warning sound controller 11 turns on the vehicle exterior speaker 2 and a warning sound is emitted basically during a period when the vehicle speed VSP is below 30 km/h. This warning sound emission is indicated in the period from time tl to time t4 in the time chart shown in section (a) of Figure 4 and in the period from time t5 to time t8 in the time chart shown in section (b) of Figure 4. The period from time tl to time t4 corresponds to a period of acceleration of the vehicle 3 from a stopped state. The period from time t5 to time t8 in the time chart shown in Figure 4 corresponds to period of deceleration of the vehicle 3 to a stop. The warning sound generally need not be emitted from the vehicle exterior speaker 2 when the vehicle speed VSP is at or about 30 km/h or higher, which indicates that the vehicle 3 is traveling in a suburban area or other area where a warning sound is not actually necessary. Also, the warning sound can be, for example, a pseudo engine sound resembling the engine sound, a driver or passenger in the vehicle 3, such as an electric or hybrid vehicle, that is capable of quiet travel will not be able to enjoy quiet travel if the pseudo engine sound is emitted continuously while the vehicle 3 is traveling on, for example, the highway or rural roads. [0044] Thus, the vehicle exterior speaker 2 is turned on and a warning sound is emitted during the periods when the vehicle speed VSP is at or below 30 km/h, which is indicated by the period between times tl and t4 in section (a) of Figure 4 and the period between times t5 and t8 in section (b) of Figure 4. Also, the vehicle exterior speaker 2 can be turned off so that a warning sound is not emitted during periods when the vehicle speed VSP is at or about 30 km/h or higher. These periods correspond, for example, to a period occurring after the time t4 in section (a) of Figure 4 and to a period occurring prior to time t5 in section (b) of Figure 4. The vehicle exterior speaker 2 can also be turned off during periods when the vehicle speed VSP is at or about 0 km/h and the vehicle 3 is stopped in a state in which a preparation for acceleration is not complete. These periods correspond to a period occurring before time tl in section (a) of Figure 4 and to a period occurring after time t8 in section (b) of Figure 4.

[0045] Also, at time tl in section (a) of Figure 4, it is generally not desirable for the warning sound to be emitted only after the vehicle 3 has started in motion. Thus, even if the vehicle speed VSP is still 0 km/h, it is preferable to determine that the acceleration preparation is completed when the brake switch 14 turns off due to the brake pedal being released. When this occurs, the vehicle exterior speaker 2 can be turned on to emit a warning sound. Furthermore, at the time t8 shown in section (b) of Figure 4, it is generally not desirable f for the warning sound to be silenced immediately when the vehicle stops. Thus, even after the vehicle speed VSP reaches 0 km/h, it is preferable to continue with the vehicle exterior speaker 2 on for a set period of time before turning the vehicle exterior speaker 2 off and silencing the warning sound. This period of time can be, for example, approximately 10 seconds or any other suitable time period.

[0046] In order to achieve the basic on-off control of the warning sound explained above with regard to sections (a) and (b) of Figure 4, the warning sound controller 1 1 determines in step S15 if the vehicle speed VSP is between 0 km/h and 30 km/h. If the vehicle speed VSP is not between 0 km/h and 30 km/h, then the warning sound controller 11 executes step S31 , step SI 2, step S13 and step S14 in sequence to turn the vehicle exterior speaker 2 off and prohibit the emission of a warning sound as discussed above.

[0047] However, if the warning sound controller 11 determines in step SI 5 that the vehicle speed VSP is within the range 0 km/h < VSP < 30 km/h (i.e., if a warning sound emission is satisfied), then the warning sound controller 11 proceeds to step S32 which corresponds to an engine operating state changing operation. That is, in step S32, the warning sound controller 1 1 sets the engine operating state change command to 1. That command is sent to the engine operation control system 6 and accordingly, the engine operating state is changed. Thus, when the warning sound controller 11 sends the engine operating state change command to the engine operation control system 6, the engine operation control system 6 controls the operation of the engine 4 so that the engine operating state is different from the normal operating state described above. This different engine control will now be explained.

[0048] That is, the engine operation control system 6 determines, for example, the quiet engine operating point Al shown in Figure 3 A which can provide the required electric power according to the battery state of charge in the quietest fashion possible, as explained previously regarding Figure 3A. However, the engine operation control system 6 does not operate the engine 4 at the quiet operating point Al . Instead, the engine operation control system 6 controls the engine 4 to operate at an operating point where the engine speed Ne2 is higher than the engine speed Nel at the quiet operating point Al by an amount ANe as shown in Figure 3A. Hence, a louder engine sound is emitted.

[0049] Also, when the rotational speed of the engine 4 is increased by the amount ANe, it is preferable to decrease an engine torque Te to a point A3 on the Pwl constant generated power curve shown in Figure 3A. By operating the engine 4 at the operating point A3, the engine 4 can be operated at a higher rotational speed while maintaining the same generated electric power Pwl .

[0050] Regardless of whether the operating point A3 is used, the supplemental engine speed ANe is set to increase the engine sound sufficiently to enable a person in a surrounding area outside the vehicle 3 to reliably hear the engine sound. Since an allowable volume of engine sound increases as the vehicle speed increases, the

supplemental engine speed ANe is preferably set to increase as the vehicle speed VSP increases, as indicated in Figure 3B. Also, the new engine operating point that is reached when the engine speed Ne is increased by the supplemental engine speed ANe is closer to an optimum fuel efficiency operating point. Thus, the fuel efficiency is improved in comparison with a fuel efficiency that would have been obtained at the quiet engine operating point Al if the engine speed had not been changed.

[0051] Furthermore, it is possible to achieve the desired outcome even if the engine torque Te is not changed when the rotational speed of the engine 4 is increased by an amount ΔΝβ. In such a case, as shown in Figure 3A, the generated electric power increases by an amount APw from Pwl to Pw2. In this case, the supplemental generated power APw is set to a power increase amount resulting in an engine speed increase amount ANe that increases the engine sound sufficiently to enable a person in a surrounding area outside the vehicle 3 to reliably hear the engine sound. Since an allowable volume of engine sound increases as the vehicle speed increases, the supplemental generated power amount APw is preferably set to increase as the vehicle speed VSP increases, as indicated in Figure 3C.

[0052] After the engine operating point is changed in step S32 of Figure 2, the warning sound controller 1 1 proceeds to step S 16 and executes on-off control of the vehicle exterior speaker 2 in accordance with an operating state of the engine 4 as discussed herein That is, in step SI 6, the warning sound controller 1 1 determines if an engine operation condition is satisfied based on, for example, engine operation control information provided to the warning sound controller 11 from the engine operation control system 6 shown in Figure 1. When the engine operation condition is satisfied, the engine operation control system 6 can immediately or at least promptly start the engine 4 and achieve a state in which the engine is running as discussed in more detail below.

[0053] However, if the warning sound controller 1 1 determines in step S 16 that the engine operation condition is not satisfied (e.g., the engine 4 is stopped), the warning sound controller 1 1 proceeds to step SI 7. In step SI 7, the warning sound controller 11 determines if it is the first cycle of the processing since the engine operation condition fails to be satisfied (e.g., since a request to stop the engine 4 was issued). If it is the first cycle, then the warning sound controller 11 processing continues to steps SI 8 and SI 9. In step SI 8, the warning sound controller 11 sets an engine stop permission flag to 0. In step SI 9, the warning sound controller 1 1 resets the engine-off timer TENGOFF to 0. The warning sound controller 11 then proceeds to step S20. Also, if it is not the first cycle in which the engine operation condition was not satisfied, the warning sound controller 11 skips steps SI 8 and S19 and goes directly to step S20.

[0054] The engine stop permission flag set in step S 18 indicates whether or not an engine stop permission signal will be sent from the warning sound controller 11 to the engine operation control system 6 shown in Figure 1. When the engine stop permission flag has a value of 0, the warning sound controller 11 does not send an engine stop permission signal to the engine operation control system 6. Accordingly, the engine operation control system 6 does not execute a request to stop the engine 4 in response to a change from a state in which the engine operation condition is satisfied to a state in which the engine operation condition is not satisfied. Instead, the engine stop request is ignored, and the engine 4 is allowed to continue running.

[0055] In step S20, the warning sound controller 11 determines if the engine-off timer TENGOFF (which was reset to 0 in step SI 9) is smaller than a prescribed value ATOFF. Initially, the value of TENGOFF is smaller than the prescribed value ATOFF because the value is 0 (TENGOFF = 0). Accordingly, the warning sound controller 11 processing continues to step S21.

[0056] In step S21 , the warning sound controller 11 increases the engine off timer TENGOFF incrementally in, for example, a step-like fashion or in any other suitable mariner. Thus, the engine off timer TENGOFF serves to measure the amount of time elapsed since the engine operation condition was determined not to be satisfied (e.g., the time since a request to stop the engine 4 was issued). In step S22, the warning sound controller 1 1 turns the vehicle exterior speaker 2 on to emit a warning sound. The processing can then end as indicated.

[0057] It should be noted that in step S20, the determining of whether the engine-off timer TENGOFF is smaller than the prescribed value ATOFF is equivalent to determining if a prescribed amount of time ATOFF has not yet elapsed since the engine operation condition was determined not to be satisfied (e.g., since a request to stop the engine 4 was issued). On the other hand, if it is determined in step S20 that the engine-off timer TENGOFF is equal to or larger than the prescribed value ATOFF, this indicates, for example, that a prescribed amount of time ATOFF has elapsed since the engine operation condition ceased to be satisfied (i.e., since a request to stop the engine 4 was issued). Accordingly, the processing performed by the warning sound controller 11 continues to step S23.

[0058] In step S23 the warning sound controller 11 sets the engine stop permission flag to 1. In step S24 the warning sound controller 11 sets the engine-off timer TENGOFF to an upper limit value. The processing then continues to step S22 as indicted. In step S22 the warning sound controller 1 1 continues emitting the warning sound by keeping the vehicle exterior speaker 2 on as discussed above. Thus, the warning sound emission control is performed as discussed above with regard to Figure 3.

[0059] Furthermore, it should be noted that when the engine stop permission flag is set to 1 in step S23, the warning sound controller 11 sends an engine stop permission signal to the engine operation control system 6 as shown in Figure 1. As a result, the engine operation control system 6 executes an engine stop request in response to the engine operation condition being no longer satisfied. As a result, the operation of the engine 4 is stopped.

[0060] It should be further noted that as long as the processing determines in step S 16 that the engine operation condition is satisfied (i.e., that the engine 4 is running), the warning sound controller 1 1 proceeds to step S26 instead of step S17 as discussed above. In step S26, the processing determines if the current control cycle is the first cycle executed since the engine operation condition came to be satisfied (i.e., since the engine 4 started running). If it is the first cycle, then the processing performed by the warning sound controller 1 1 proceeds to step S27. In step S27, the engine-on timer TENGON is set to 0 before proceeding to step S28. However, if it is not the first cycle, then the processing performed by the warning sound controller 11 skips step S27 and proceeds directly to step S28.

[0061] In step S28, the warning sound controller 1 1 determines if the engine-on timer TENGON (which was reset to 0 in step S27) is smaller than a prescribed value ΔΤΟΝ. Initially, the value of TENGON is smaller than the prescribed value ΔΤΟΝ because the value is 0 (TENGON = 0), and the warning sound controller 1 1 proceeds to step S29.

[0062] In step S29, the warning sound controller 11 increases the engine-on timer TENGON incrementally in, for example, a step-like fashion or in any other suitable manner. Thus, the engine-on timer TENGON serves to measure the amount of time that has elapsed since the engine operation condition was determined to be satisfied (i.e., since the engine 4 started operating). The processing then continues to step S22. In step S22, the warning sound controller 1 1 turns the vehicle exterior speaker 2 on to emit a warning sound as discussed above.

[0063] On the contrary, if the processing determines in step S28 that the value of the engine-on timer TENGON is equal or larger than the prescribed value ΔΤΟΝ, the processing thus determines that the prescribed amount of time ΔΤΟΝ has elapsed since the engine operation condition became satisfied (i.e., since the engine 4 started operating). Accordingly, the processing performed by the warning sound controller 11 proceeds to step SI 3. As discussed above, in step S13 the warning sound controller 11 sets the engine-on timer TENGON to an upper limit value. As further discussed above, in step S 14 the warning sound controller 11 turns the vehicle exterior speaker 2 off so that a warning sound is not emitted.

[0064] The on-off control of the vehicle exterior speaker 2 (warning sound) according to Figure 2 will now be further explained with reference to the operation time charts shown in Figure 5. It should be noted that sections (a) and (b) of Figure 5 correspond to accelerating from a stopped condition and decelerating to a stop, respectively, in a manner similar to sections (a) and (b) of Figure 4 as discussed above.

[0065] At time tl in Figure 4, preparation for acceleration from a stopped condition is complete for the vehicle 3. The warning sound controller 1 1 thus performs operations of the control program shown in Figure 2 that include steps SI 1, SI 5, S32, SI 6, SI 7, S20, S21 and S22 as discussed above. By executing step S32 the warning sound controller 1 1 sets an engine operating state change command to 1, Also, by executing step S22, the warning sound controller 11 turns the vehicle exterior speaker 2 so that a warning sound is emitted.

[0066] With the warning sound, vehicle information can be conveyed to a person in a surrounding area outside of the vehicle 3 even if the engine operating sound is not being emitted because, for example, the engine 4 is stopped. Also, since the value of the engine- · off timer TENGOFF is reset to 0 in step S 12 until the time tl is reached (e.g., until the vehicle speed becomes greater than 0 km/h), the incrementing of the engine-off timer TENGOFF executed in step S21 measures the time that has elapsed since the time tl, as shown in the bottommost plot of Figure 5. However, the engine-off timer TENGOFF is not used at the time of acceleration from a stopped condition, which is before section (a) that begins at time tl in Figure 5.

[0067] With the warning sound, vehicle information can be conveyed to a person in a surrounding area outside the vehicle even if the engine operating sound is not being emitted because the engine 4 is stopped. Since the value of the engine off timer

TENGOFF is reset to 0 in step S12 until the time tl is reached, the incrementing of the engine off timer TENGOFF executed in step S21 serves to measure the time elapsed since the time tl , as shown in the bottommost plot of section (a) of Figure 5. However, the engine off timer TENGOFF is not used at the time of acceleration from a stopped condition shown in section (a) of Figure 5.

[0068] At the time t2 in Figure 5, the engine operation condition is satisfied due to the accelerator pedal being depressed deeply. Hence, the engine operation control system 6 shown in Figure 1 starts the engine 4 immediately or almost immediately by issuing the engine operation command shown at time t2 in Figure 5. Thus, since the engine 4 is started immediately or almost immediately when the engine operation condition is satisfied at time t2, a request for energy from the engine 4 can be satisfied promptly. This can be advantageous from the standpoint of energy response.

[0069] At time t2 when the engine operation condition is satisfied, the warning sound controller 11 initially performs operations of the control program shown in Figure 2 that include steps SI 1 , SI 5, S32, SI 6, S26, S27, S28, S29 and S22. Starting from the second cycle afterward, the warning sound controller 1 1 performs operations of the control program shown in Figure 2 that include steps SI 1, SI 5, S32, SI 6, S26, S28, S29 and S22.

[0070] That is, starting from the engine start time t2 of Figure 5, the warning sound controller 1 1 keeps the vehicle exterior speaker 2 on and continues emitting the warning sound by executing step S22. During this period, the engine-on timer TENGON (which was reset to 0 in step S27 during the initial cycle) is incremented in step S29 starting from the second cycle. Accordingly, the engine-on timer TENGON measures the time that has elapsed since the engine start time t2 as shown in Figure 5.

[0071] At time t3, the engine-on timer TENGON reaches the prescribed value ΔΤΟΝ, thus indicating that the time that has elapsed since the engine start time t2 reaches a prescribed amount of time ΔΤΟΝ. In this event, the warning sound controller 11 processing proceeds from step S28 to step SI 3, and begins performing operations of the control program shown in Figure 2 that includes steps SI 1, SI 5, S32, SI 6, S26, S28, S13 and S14.

[0072] That is, at the time t3, the warning sound controller 1 1 sets the engine-on timer TENGON to the upper limit value as shown in Figure 4 by executing step SI 3. The warning sound controller 11 also turns off the vehicle exterior speaker 2 to stop emitting the warning sound by executing step SI 4. However, even though the vehicle exterior speaker 2 is turned off so that a warning sound is not emitted, the engine 4 emits an operating sound starting at time t2. Therefore, a person in a surrounding area outside the vehicle 3 can obtain vehicle information from the engine operating sound, which acts as a warning sound.

[0073] Also, since the engine operating state change command is set to 1 at the time tl, when the engine 4 is started at the time t2, the engine 4 is operated at a rotational speed Ne. The rotation speed Ne is higher than a normal (quiet) operating speed by the supplemental engine speed ANe explained previously with reference to Figure 4. This engine speed control is indicated with hatching in section (a) of Figure 5.

[0074] As discussed above, the change of the engine operating state to a higher-speed state increases the engine sound and enables a person in a surrounding area outside the vehicle 3 able to hear the engine sound more reliably. Thus, the person can obtain vehicle information reliably from the engine sound without a warning sound being emitted from the vehicle exterior speaker 2. Furthermore, as explained previously with reference to Figure 3 A, the change of the engine operating state to a higher-speed state shifts the operating point of the engine 4 to an operating point where the fuel efficiency is better than at the aforementioned quiet operating point, thus enabling the fuel efficiency to be improved. Also, since an allowed volume of engine sound increases at higher vehicle speeds, the size of the supplemental engine rotational speed ANe can be increased as the vehicle speed VSP increases, as explained previously with reference to Figures 3B and 3C. Thus, since the engine sound is increased in accordance with increasing vehicle speed, the previously explained operational effect can be achieved when the vehicle speed is high without causing a person in a surrounding area to feel that something is unusual about the sound of the vehicle 3.

[0075] At time t4 shown in Figure 5, which is the end of section (a), the vehicle speed VSP reaches 30 km/h. When this occurs, the warning sound controller 1 1 performs operations of the control program shown in Figure 2 that include the steps SI 1, SI 5, S31 , S12, S13 and S14. The warning sound controller 11 resets the engine operating state change command to 0 in step S31, and resets the engine-off timer TENGOFF to 0 as shown in Figure 4 by executing step SI 2. The warning sound controller 1 1 also keeps the vehicle exterior speaker 2 off so that a warning sound is not emitted from the vehicle exterior speaker 2 by executing step S14.

[0076] In addition, at a time t4 shown in Figure 5, when the warning sound emission condition ceases to be satisfied, the engine operating state change command is set to 0 in step S31 as explained above. As a result, the engine 4 is restored from the aforementioned high-speed operating state to a normal operating state by decreasing the engine speed Ne by the amount ANe and returning to a normal (quiet) operating speed. By restoring the engine speed Ne to a normal (quiet) operating speed at the time t4 when the warning sound emission condition ceases to be satisfied, a situation in which the engine speed remains loud when warning sound emission condition is no longer satisfied can be avoided.

[0077] When the engine rotational speed Ne is decreased back to a normal operating speed, the engine rotational speed Ne is changed over time. This change is indicated with the reference symbol a immediately or almost immediately after the time t4 when the warning sound emission condition ceases to be satisfied. More specifically, the engine rotational speed Ne is gradually decreased to the normal operating speed at a prescribed amount of change per unit time. Thus, the warning sound controller 11 is configured to change the engine operating state at a prescribed rate of change per unit time. This gradual decreasing prevents a sudden change in both the engine speed Ne and the engine sound.

[0078] As can be appreciated from the above, with the on-off control of the vehicle exterior speaker 2 (warning sound) shown in Figure 2, the vehicle exterior speaker 2 is kept on so that a warning sound continues to be emitted during a period from the engine start time t2 until the time t3 when the prescribed time ΔΤΟΝ has elapsed since the time t2, as shown in Figure 4. Thus, even if the engine starts and emits an engine sound, the warning sound continues to be emitted such that both the engine sound and the warning sound are emitted for the duration of the prescribed amount of time ΔΤΟΝ. Accordingly, the warning sound controller 11 is configured to control the vehicle exterior speaker 2 (warning sound emitting component) to emit the warning sound to convey vehicle information to a person in a surrounding area outside the vehicle 3 while a prescribed warning sound emission condition is satisfied. This ensures that both the engine sound and the warning sound are audible by the person during a prescribed period of time when the warning sound controller 1 1 controls the vehicle exterior speaker 2 (warning sound emitting component) to switch between emitting the warning sound and silencing the warning sound based on whether the engine is stopped or running.

[0079] The warning sound controller 1 1 is further configured to change an operating state of an engine 4 of the vehicle 3 such that an engine sound emitted by the engine 4 while the warning sound emission condition is satisfied is louder than the engine sound that is emitted by the engine 4 when the warning sound emission condition is not satisfied. Furthermore, warning sound controller 1 lis configured to vary a volume of the engine sound as discussed above while the warning sound emission condition is satisfied.

[0080] Consequently, abrupt switching from the warning sound to the engine sound can be avoided in a reliable fashion. As a result, movement of the vehicle 3 as indicated by the warning sound matches or substantially matches movement of the vehicle 3 as indicated by the subsequently emitted engine sound. Hence, a person in a surrounding area outside the vehicle 3 can obtain vehicle information in an uninterrupted manner without experiencing a feeling that something is unusual about the sound of the vehicle.

[0081] Also, a silent period in which neither the engine sound nor the warning sound is emitted can be reliably avoided. As a result, it is possible to avoid or at least reduce the occurrence of a situation in which a person in a surrounding area outside the vehicle 3 cannot easily understand the vehicle information due to the occurrence of such a silent period, and inadvertently believes that the vehicle 3 has temporarily moved farther away

[0082] At time t5 shown in Figure 4, the vehicle speed VSP decreases below 30 km/h due to deceleration. This begins section (b) of Figure 4. Hence, at time t5, the warning sound controller 11 switches from performing operations of the control program shown in Figure 2 that include the steps SI 1, S31, SI 2, S13 and SI 4 discussed previously, to performing operations that include the steps SI 1, S15, S32, S16, S26, S28, S13 and S14. By continuing to execute step S I 4, the warning sound controller 1 1 keeps the vehicle exterior speaker 2 off so that a warning sound is not emitted from the vehicle exterior speaker 2. However, vehicle information can be conveyed to a person in a surrounding area outside the vehicle 3 because the engine operation control system 6 shown in Figure 1 is still operating the engine 4 with the engine operation command as shown in Figure 5.

[0083] Prior to the time t5, when the warning sound emission condition became satisfied, the warning sound controller 11 shown in Figure 1 sets the engine operating state change command to 0 so the command is not sent to the engine operation control system 6. Thus, the engine 4 is controlled to operate in a normal operating state and not in the highspeed operating state as discussed above. When the warning sound emission condition is satisfied at the time t5, the processing is changed as explained above so that the step S32 is executed. Accordingly, the engine operating state change command is sent from the warning sound controller 11 to the engine operation control system 6 as shown in Figure 1. As a result, the engine 4 is switched from a normal operating state to a high-speed operating state.

[0084] Thus, the engine 4 is operated at a rotational speed that is higher than the normal (quiet) operating speed by an amount equal to the supplementary engine speed ΔΝε shown in Figure 3. This operational control is indicated with hatching in section (b) of Figure 5. When the engine rotational speed Ne is increased, the engine rotational speed Ne is changed over time as indicated with the reference symbol β immediately or almost immediately after the time t5 shown in section (b) of Figure 5. More specifically, the engine rotational speed Ne is gradually increased at a prescribed amount of change per unit time to prevent or at least reduce a sudden change in both the engine speed Ne and the engine sound. Thus, the warning sound controller 11 is configured to change the engine operating state at a prescribed rate of change per unit time.

[0085] The change of the engine operating state to a higher speed increases the engine sound and enables a person in a surrounding area outside the vehicle 3 to hear the engine sound more reliably. Thus, the person can obtain vehicle information reliably from the engine sound without the vehicle exterior speaker 2 having to emit a warning sound. Furthermore, as explained previously with reference to Figure 3A, the change of the engine operating state to a higher-speed state shifts the operating point of the engine 4 to an operating point where the fuel efficiency is better than at the quiet operating point, thus improving the fuel efficiency of the vehicle 3. Also, since the volume of the engine sound increases at higher vehicle speeds, the size of the supplemental engine rotational speed ΔΝε can be increased as the vehicle speed VSP increases, as explained previously with reference to Figures 3B and 3C. Thus, since the engine sound is increased in accordance with increasing vehicle speed, the operational effect discussed above can be achieved when the vehicle speed is high without causing a person in a surrounding area to sense that the sound of the vehicle 3 is unusual.

[0086] At a time t6 shown in section (b) of Figure 5, the engine operation condition is no longer satisfied because, for example, the battery state of charge has recovered. The engine operation control system 6 shown in Figure 1 immediately or almost immediately issues an engine stop request to turn the engine operation command off as indicated by a broken line in section (b) of Figure 5.

[0087] As a result, the warning sound controller 11 initially performs operations including steps SI 1 , S I 5, S32, S I 6, SI 7, SI 8, SI 9, S20, S21 and S22 of the control program shown in Figure 2. Starting from the second cycle afterwards, the warning sound controller 11 performs operations including steps SI 1, S15, S32, S16, S17, S20, S21 and S22.

[0088] Starting from the time t6 of Figure 5, when the engine stop request is issued, the vehicle exterior speaker 2 is turned on and a warning sound is emitted due to the execution of step S22. During this period, the engine stop permission flag is initially reset to 0 in step SI 8, and the reset state continues even afterward. Consequently, the warning sound controller 11 shown in Figure 1 does not send the engine stop permission signal to the engine operation control system 6. As a result, the engine operation control system 6 does not execute the engine stop request by turning the engine operation command off at the time t6 as indicated with the broken line in Figure 5. Instead, the engine operation control system 6 keeps the engine operation command on as indicated with a solid line so that the engine 4 continues to run. [0089] In the first control cycle after the engine stop request time t6 of Figure 4 is reached, the engine-off timer TENGOFF is reset to 0 in step SI 9. Then, starting from the second cycle, the value of the engine-off timer TENGOFF is incremented in step S21. Thus, the engine-off timer TENGOFF measures the amount of time that has elapsed since the engine stop request time t6 occurred as shown in Figure 5.

[0090] At time t7, the engine-off timer TENGOFF reaches the prescribed value ATOFF. When the time that has elapsed since the engine stop request time t6 reaches a prescribed amount of time ATOFF, the warning sound controller 1 1 proceeds from step S20 to step S23. The warning sound controller 1 1 then begins performing operations of the control program shown in Figure 2 that includes steps SI 1 , SI 5, S32, SI 6, SI 7, S20, S23, S24, and S22.

[0091] At the time t7, the warning sound controller 1 1 sets the engine stop permission flag to 1 by executing step S23, and sends an engine stop permission signal to the engine operation control system 6. As a result, at the time t7 of Figure 5, the engine operation control system 6 turns off the engine operation command as indicated with the solid line, and executes the engine stop request. Thus, the engine operation control system 6 waits until the time t7 before stopping the operation of the engine 4 in response to the stop request issued at the time t6.

[0092] Even after the engine 4 is stopped at time t7, the vehicle exterior speaker 2 stays on as continuing from the time t6 to emit a warning sound. Thus, a person in a surrounding area outside the vehicle 3 can obtain vehicle information from the warning sound. At time t7, the warning sound controller 11 sets the engine-off timer TENGOFF to the upper limit value as indicated in Figure 4 by executing step S24. In the example illustrated in Figure 4, the engine-on timer TENGON does not change after being set to an upper limit value in step SI 3. The engine-on timer TENGON thus remains at the upper limit value as indicated in Figure 4.

[0093] At time t8, which is the end of section (b) in Figure 4, the vehicle speed VSP reaches Okrn/h. Accordingly, the warning sound controller 11 begins performing operations of the control program shown in Figure 2 that includes the steps S11, S15, S12, S13 and SI 4. The warning sound controller 11 resets the engine-off timer TENGOFF to 0 as shown in Figure 5 by executing step SI 2. The warning sound controller 1 1 also turns the vehicle exterior speaker 2 off by executing step S14 so that a warning sound is no longer emitted by the vehicle exterior speaker 2.

[0094] As can be appreciated from the above, with the on-off control of the vehicle exterior speaker 2 (warning sound) shown in Figure 2, the vehicle exterior speaker 2 is turned on immediately or almost immediately at an engine stop request time t6 so that a warning sound is emitted. Meanwhile, execution of the engine stop request is delayed and the engine 4 continues running from the engine stop request time t6 until time t7 when a prescribed amount of time ATOFF has elapsed. Thus, even after the vehicle exterior speaker 2 is turned ON and the warning sound is emitted, engine 4 continues running such that both the engine sound and the warning sound are emitted for the duration of the prescribed amount of time ATOFF.

[0095] Consequently, an abrupt switch from the engine sound to the warning sound can be avoided in a reliable fashion. As a result, a movement of the vehicle 3 indicated by the engine sound matches a movement of the vehicle 3 indicated by the subsequently emitted warning sound. Therefore, a person in a surrounding area outside the vehicle 3 can obtain vehicle information in an uninterrupted manner without experiencing a feeling that something is unusual about the sound of the vehicle 3.

[0096] Also, a silent period in which neither the engine sound nor the warning sound is emitted can be reliably avoided. As a result, it is possible to prevent or at least reduce an occurrence of a situation in which a person in a surrounding area outside the vehicle cannot easily understand the vehicle information due to the occurrence of such a silent period and inadvertently believes that the vehicle 3 has temporarily moved farther away.

[0097] Further details will now be described pertaining to the prescribed amount of time ΔΤΟΝ used to delay turning the vehicle exterior speaker 2 from on to off, and the prescribed amount of time ATOFF used to delay stopping the engine as discussed above.

[0098] In order to achieve the operational effect illustrated in Figure 5, the vehicle exterior speaker 2 remains on and continues to emit the warning sound for a period of time after the engine 4 is started at the time t2 shown in Figure 5. In other words, the vehicle exterior speaker 2 remains on until a person in a surrounding area outside the vehicle 3 can recognize the engine sound. The prescribed amount of time ΔΤΟΝ is used to delay the switch of the vehicle exterior speaker 2 from an on state to an off state for the aforementioned period of time. Thus, the prescribed amount of time ΔΤΟΝ used for delaying the on-to-off transition of the vehicle exterior speaker 2 can be set to a constant value that does not depend on the vehicle speed VSP, as indicated with a broken line in Figure 6A, for example.

[0099] However, the amount of time required for a person in a surrounding area outside the vehicle to recognize the engine sound after the engine 4 is started at the time t2 shown in Figure 4 tends to be longer when the vehicle speed VSP (i.e., the speed of the vehicle 3 relative to the ground) is higher. Thus, it is preferable to set the prescribed amount of time ΔΤΟΝ used to delay the on-to-off transition of the vehicle exterior speaker 2 such that the amount of time lengthens as the vehicle speed VSP increases, as indicated with a solid line in Figure 6A.

[00100] In addition, to achieve the operational effect illustrated in Figure 5, the engine 4 keeps running and execution of an engine stop request is delayed for a period of time after the vehicle exterior speaker 2 is turned on at the time t6 shown in Figure 5. That is, the engine 4 keeps running until a person in a surrounding area outside the vehicle 3 can recognize the engine sound. The prescribed amount of time ATOFF is used to delay execution of the engine stop for the aforementioned period of time. Thus, the prescribed amount of time ATOFF used for delaying the engine stop can be set to a constant value that does not depend on the vehicle speed VSP, as indicated with a broken line in Figure 6B, for example.

[00101] However, the amount of time required for a person in a surrounding area outside the vehicle 3 to recognize the warning sound after vehicle exterior speaker 2 is turned on at the time t6 shown in Figure 4 tends to be longer when the vehicle speed VSP (i.e., the speed of the vehicle 3 relative to the ground) is higher. Thus, it is preferable to set the prescribed amount of time ATOFF used to delay the engine stop such that the amount of time lengthens as the vehicle speed VSP increases, as indicated with a solid line in Figure 6B.

[00102] As can be appreciated from the above description and as shown in Figure 5, a warning sound is emitted from the speaker 2 while the warning sound emission condition is satisfied so that vehicle information is conveyed to a person in a surrounding area outside the vehicle 3. Conversely, when the engine 4 is running, the speaker 2 is not operated and a warning sound is not emitted. Instead, vehicle information is conveyed to a person in a surrounding area outside the vehicle 3 by the engine sound. However, the same or similar operational effects can be achieved when the speaker 2 emits a warning sound even while the warning sound emission condition is satisfied and the engine 4 is running.

[00103] Also, when the engine speed Ne is increased by an amount ANe such that the engine sound increases while the warning sound emission condition is satisfied, the amount ANe that the engine speed is increased can be controlled so the engine sound varies and thus becomes louder and softer. The variation of the engine sound can enable a person in a surrounding area outside the vehicle 3 to more readily recognize the existence of the vehicle 3. As can also be appreciated, a magnitude of a difference between a volume of the engine sound when the warning sound emission condition is satisfied and a volume of the engine sound when the warning sound emission condition is not satisfied is proportional to a speed of the vehicle 3. That is, the difference increases as the speed of the vehicle 3 increases.

[00104] Furthermore, the vehicle 3 in the examples discussed above is a series hybrid vehicle, the vehicle 3 can be a parallel hybrid vehicle having an electric drive mode (EV mode) in which the vehicle 3 is driven solely with an electric motor 5 and a hybrid mode (HEV mode) in which the vehicle 3 is driven with power from both an engine 4 and the electric motor 5. Hence, the same or similar operational effects can be achieved even when the vehicle 3 is a parallel hybrid vehicle or other suitable type of vehicle.

[00105] In summary, the vehicle warning sound emitting apparatus 1 changes an operating state of the engine 4 such that an engine sound is louder while the warning sound emission condition is satisfied than when the warning sound emission condition is not satisfied. Also, if the engine 4 is running during a period when the warning sound emission condition is satisfied, a person in a surrounding area outside the vehicle 3 can also obtain vehicle information from the engine sound.

[00106] Since the engine operating state is changed such that the engine sound is louder during a period when the warning sound emission is satisfied than during a period when the warning sound emission condition is not satisfied, a person in a surrounding area outside the vehicle 3 can obtain vehicle information reliably from the increased engine sound. Moreover, the fuel efficiency of the vehicle 3 can be improved because the engine 4 is operated at an operating point where the fuel efficiency is better than at a quiet operating point.

GENERAL INTERPRETATION OF TERMS

[00107] In understanding the scope of the present invention, the term "comprising" and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, "including", "having" and their derivatives. Also, the terms "part," "section," "portion," "member" or "element" when used in the singular can have the dual meaning of a single part or a plurality of parts. Also as used herein to describe the above

embodiment(s), the following directional terms "forward", "rearward", "above",

"downward", "vertical", "horizontal", "below" and "transverse" as well as any other similar directional terms refer to those directions of a vehicle equipped with the vehicle warning sound emitting apparatus. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a vehicle equipped with the vehicle warning sound emitting apparatus.

[00108] The term "detect" as used herein to describe an operation or function carried out by a component, a section, a device or the like includes a component, a section, a device or the like that does not require physical detection, but rather includes determining, measuring, modeling, predicting or computing or the like to carry out the operation or function.

[00109] The term "configured" as used herein to describe a component, section or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function.

[00110] The terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.

[00111] While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired.

Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A vehicle warning sound emitting apparatus comprising:

a warning sound emitting component configured to selectively emit a warning sound that is audible outside of the vehicle; and

a controller configured to control the warning sound emitting component to emit the warning sound to convey vehicle^'information to a person in a surrounding area outside the vehicle while a prescribed warning sound emission condition is satisfied, and the controller being further configured to change an operating state of an engine of the vehicle such that an engine sound emitted by the engine while the warning sound emission condition is satisfied is louder than the engine sound that is emitted by the engine when the warning sound emission condition is not satisfied.

2. The vehicle warning sound emitting apparatus recited in claim 1 , wherein the controller is further configured to control the warning sound emitting component to emit the warning sound to convey the vehicle information to the person in the surrounding area outside the vehicle while the warning sound emission condition is satisfied, and to control the engine to emit the vehicle engine sound such that the vehicle engine sound, instead of the warning sound, conveys the vehicle information to the person in the surrounding area outside the vehicle while the engine is running.

3. The vehicle warning sound emitting apparatus recited in claim 1 or 2, wherein

the controller is further configured to change the engine operating state between a changed state and an original state at a prescribed rate of change per unit time.

4. The vehicle warning sound emitting apparatus recited in any one of claims 1 to 3, wherein

the controller is further configured to change the engine operating state such that a magnitude of a difference between a volume of the engine sound when the warning sound emission condition is satisfied and a volume of the engine sound when the warning sound emission condition is not satisfied is proportional to a speed of the vehicle, so that the difference increases as the speed increases.

5. The vehicle warning sound emitting apparatus recited in any one of claims

1 to 4, wherein

the controller is further configured to vary a volume of the engine sound while the warning sound emission condition is satisfied.

6. The vehicle warning sound emitting apparatus recited in any one of claims

2 to 5, wherein

the controller is further configured to control the warning sound emitting component and the engine to ensure that both the engine sound and the warning sound are audible by the person during a prescribed period of time when the controller controls the warning sound emitting component to switch between emitting the warning sound and silencing the warning sound based on whether the engine is stopped or running.

7. The vehicle warning sound emitting apparatus recited in claim 6, wherein the controller is further configured to control the warning sound emitting component such that when a transition from an engine stopped state to an engine running state occurs, the warning sound emitting component delays silencing the warning sound for a prescribed period of time from a time of the transition.

8. The vehicle warning sound emitting apparatus recited in claim 6 or 7, wherein

the controller is further configured to control the warning sound emitting component to begin emitting the warning sound in response to a request to transition from the engine running state to the engine stopped state while controlling the engine to delay the transition from the engine running state to the engine stopped state for a prescribed period of time from a time of the request.

9. The vehicle warning sound emitting apparatus recited in any one of claims 6 to 8, wherein

the prescribed period corresponds to an amount of time for a person at the location outside the vehicle to recognize that the engine sound is emitted subsequent to the emitting of the warning sound or vice-versa.

10. The vehicle warning sound emitting apparatus recited in any one of claims 6 to 9, wherein

the controller is further configured to set the prescribed period of time based on a speed of the vehicle, such that the prescribed period of time increases as the speed of the vehicle increases.