Vehicle fuel mileage meter

A vehicle fuel mileage meter capable of displaying a value approximate to a fuel mileage obtained from actual driving only is provided. The fuel mileage meter includes a fuel mileage display and a control unit. The control unit controls display of a fuel mileage on the fuel mileage display based on a distance traveled and an amount of fuel consumed after a vehicle speed exceeds a predetermined threshold.

FIELD OF THE INVENTION

The present invention relates to an improvement in a fuel mileage meter for displaying a rate of fuel consumption of a vehicle.

BACKGROUND OF THE INVENTION

Fuel consumption is generally expressed in a rate (hereinafter referred to as “fuel mileage”). Fuel mileage is provided by dividing an amount of consumed fuel by a traveled distance.

In a certain conventional fuel mileage meter, fuel mileage is calculated in accordance with the following steps:

STEP (hereinafter abbreviated as ST)101: Determination is made as to whether an ignition is “ON.” In other words, it is determined whether an engine is started. When the answer is YES, the process proceeds to ST102, and when NO, repeats ST101.

ST102: Measurement of distance of travel is started.

ST103: Measurement of the amount of consumed fuel is started.

ST104: It is determined whether the ignition is “OFF.” When the answer is YES, the process proceeds to ST105, and when NO, repeats ST104.

ST105: Fuel mileage is calculated.

ST106: The fuel mileage is displayed.

In the conventional fuel mileage calculation method, measurement of the amount of consumed fuel is performed from the start of the engine for eventual fuel mileage display. Upon start, engines are in an idling state. Inclusion for display of fuel consumption in such an idling state adversely affects the usefulness of fuel mileage display.

Assume that after an engine is started, an idling time of ten minutes is required to wait for someone, and thereafter the vehicle travels along a crowded street. Fuel mileage displayed in such a case is estimated to be smaller than that in the case of traveling along a non-crowded street or an expressway. In certain instances, it should be clarified whether the smaller fuel mileage resulted from the idling or travel along a crowded street.

Thus, demand grows for capability to display fuel mileage reflecting fuel consumption from actual driving and for enhanced usefulness of fuel mileage display.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a vehicular fuel mileage meter which comprises: a fuel mileage display for displaying a rate of fuel consumption of a vehicle; and a control unit for controlling display of the fuel consumption rate on the fuel mileage display based on a distance traveled and an amount of fuel consumed after a vehicle speed exceeds a predetermined threshold.

If the displayed fuel mileage is one obtained from actual driving only, it can be utilized as useful information for the driver. Also, the driver can easily become aware that “the driving with relatively fewer waits at stoplights has led to the improved fuel economy” or “the driving along a crowded street has led to the bad fuel economy,” for example.

Accordingly, as described above, the control unit is provided for controlling display of the fuel mileage on the fuel mileage display based on the traveled distance and the amount of fuel consumed after the vehicle speed exceeds the predetermined threshold, with the amount of fuel consumed during idling at the start, for example, excluded from the fuel mileage calculation. As a result, a value of fuel mileage close to a fuel mileage in actual traveling can be displayed to thereby provide the driver with the useful fuel mileage information.

Preferably, the control unit comprises a traveled distance calculator for calculating the distance traveled after the vehicle speed exceeds the predetermined threshold, a consumed fuel amount calculator for calculating the amount of fuel consumed after the vehicle speed exceeds the predetermined threshold, and a fuel mileage calculator for calculating fuel mileage based on the traveled distance and the consumed fuel amount.

The fuel mileage display is preferably provided at a meter indicator portion provided in an instrument panel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Initial reference is made toFIG. 1showing in perspective a vehicle compartment equipped with a meter unit which includes a vehicle fuel mileage meter according to the present invention. In the figure, reference numeral10denotes a vehicle,11a passenger compartment,12an instrument panel,13a windshield,14an A-pillar,15a glove box,16a shift lever,17a handbrake,18a steering wheel,21an ignition switch,22an ignition key,23a door,24a door lock,25a door switch,26a clock, and30a meter unit.

FIG. 2illustrates the meter unit30including the vehicle fuel mileage meter of the present invention. The meter unit30consists of a meter indicator portion31for showing vehicle information, time information, driving conditions information and the like, a housing32containing the meter indicator portion31, and a clear cover33put over the housing32to transparently cover the meter indicator portion31.

The meter indicator portion31has a speedometer35for indicating vehicle speed, a tachometer36for indicating the number of revolutions of an engine, a coolant temperature gauge37for indicating the temperature of coolant, a fuel gauge38for indicating the remaining amount of fuel, a liquid crystal display39for showing integrated distance, traveled distance or air temperature, a switch41for switching the displayed contents of the liquid crystal display39, a fuel mileage display43as a display member of the vehicle fuel mileage meter42for showing a rate of fuel consumption (fuel consumption), a display button45for displaying fuel mileage on the fuel mileage display43, an abnormality display47for showing abnormality or malfunction, and an illuminating means44for illuminating the speedometer35, tachometer36, coolant temperature gauge37, fuel gauge38, liquid crystal display39, fuel mileage display45and abnormality display47.

In the figure, reference numeral46denotes a character board for showing graphics or characters of the meter indicator portion31. More specifically, the character board46has a dial51of the speedometer35, a dial52of the tachometer36, a dial53of the coolant temperature gauge37, a dial54of the fuel gauge38, a display window55of the liquid crystal display39, a display window48of the fuel mileage display43, and a display window49of the display47for showing abnormality or malfunction.

Reference numeral56denotes a needle of the speedometer35,57a needle of the tachometer36,58a needle of the coolant temperature gauge37, and59a needle of the fuel gauge38.

Next, reference is made toFIG. 3illustrating a specific example of the illuminating means44in the meter unit30ofFIG. 2.

The illuminating means44includes a dial illuminating means61for illuminating the dials51to54, a needle illuminating means62for illuminating the needles56to59, a liquid-crystal-illuminating LED (light emitting diode)63for illuminating the liquid crystal display39and fuel mileage display43, and a display-illuminating LED64for illuminating the abnormality display47for showing abnormality or malfunction.

The dial illuminating means61consists of a group of character-illuminating LEDs65for illuminating the dial51of the speedometer35, a group of character-illuminating LEDs for illuminating the dial52of the tachometer36, a group of character-illuminating LEDs71for illuminating the dial53of the coolant temperature gauge37, and a group of character-illuminating LEDs72for illuminating the dial54of the fuel gauge38.

The needle illuminating means62consists of a group of needle-illuminating LEDs75for illuminating the needle56of the speedometer35, a group of needle-illuminating LEDs77for illuminating the needle57of the tachometer36, a group of needle-illuminating LEDs81for illuminating the needle58of the coolant temperature gauge37, and a group of needle-illuminating LEDs82for illuminating the needle59of the fuel gauge38.

Now, a configuration of the speedometer35will be described with reference toFIG. 4.

The speedometer35consists of a base plate84supported on the housing32, a meter body85mounted on the base plate84, the needle56mounted on the meter body85, the dial51for showing the vehicle speed at the position pointed by the needle56, the character-illuminating LED group65for illuminating the dial51, a dial light guide86for guiding light of the character-illuminating LED group65to the dial51, an illumination case87enclosing the dial light guide86to prevent the leakage of light of the character-illuminating LED group65and also serving as a reflector, the needle-illuminating LED group75for illuminating the needle56, a needle light guide88for guiding light of the needle-illuminating LED group75to the needle56, and a partitioning member89for separating the needle light guide88from the dial light guide86.

The tachometer36, coolant temperature gauge37and fuel gauge38shown inFIG. 2each have a substantially identical configuration to that of the speedometer35, and will not be described in detail.

The base plate84is a single base plate on which the speedometer35, tachometer36, coolant temperature gauge37, fuel gauge38and liquid crystal display39are mounted.

FIG. 5illustrates the liquid crystal display39of the meter unit30including the vehicle fuel mileage meter42according to the present invention.

The liquid crystal display39and fuel mileage display43include the base plate84on which the speedometer35(seeFIG. 4) and other components are mounted, a liquid-crystal-illuminating LED63mounted on the base plate84, a holder91mounted on the base plate84, a liquid crystal light guide93mounted on the holder91, a liquid crystal device (LCD)92for the liquid crystal display39placed on the liquid crystal light guide93and mounted on the base plate84, and a liquid crystal device94for the fuel mileage display43placed on the liquid crystal light guide93and mounted on the base plate84. Light from the liquid-crystal-illuminating LED63is guided by the liquid crystal light guide93to the rear surfaces of the liquid crystal devices92and94, illuminating the liquid crystal devices92and94. On the fuel mileage display43, fuel mileage is displayed via a control unit101as will be described below.

The abnormality display47shown inFIG. 6for showing abnormality in various systems of the vehicle10has a substantially identical configuration to that of the liquid crystal display39and fuel mileage display43shown inFIG. 5. Reference numeral64denotes a display-illuminating LED,84the base plate,96a holder,97a color LCD, and98a color LCD light guide.

FIG. 7is a block diagram of the vehicle fuel mileage meter42of the present invention. The vehicle fuel mileage meter42consists of the fuel mileage display43for showing fuel mileage, the control unit101for controlling display of fuel mileage on the fuel mileage display43based on the distance traveled and the amount of fuel consumed after the vehicle speed exceeds a predetermined threshold, and the display button45for making the fuel mileage display43to display fuel mileage.

The control unit101consists of a speed determiner105to determine whether the vehicle speed exceeds a predetermined threshold based on information from a speed sensor102, a traveled distance calculator106for calculating the distance traveled based on information from the speed sensor102, a consumed fuel amount calculator107for calculating the amount of fuel consumed based on information from a fuel detector103, a fuel mileage calculator108for calculating fuel mileage from the traveled distance and the consumed fuel amount calculated by the traveled distance calculator106and the consumed fuel amount calculator107, and a display drive controller109for drive control for displaying fuel mileage calculated by the fuel mileage calculator108on the fuel mileage display43. Reference numeral104denotes an ignition.

In summary, the vehicle fuel mileage meter42has the fuel mileage display43for displaying the fuel mileage of the vehicle10(seeFIG. 1) and the control unit101for controlling display of fuel mileage on the fuel mileage display43based on the distance traveled and the amount of fuel consumed after the vehicle speed exceeds the predetermined threshold.

If the displayed fuel mileage is one from actual driving, it can be utilized as useful information for the driver. The driver can be easily aware that “the driving with relatively less waits at stoplights has led to the improved fuel economy” or “the driving down crowded streets has led to the lower fuel economy,” for example.

For the purpose, the control unit101for controlling display of fuel mileage on the fuel mileage display43based on the distance traveled and the amount of fuel consumed after the vehicle speed exceeds the predetermined threshold is provided to exclude the amount of fuel consumed in idling at starting, for example, from the calculation of fuel mileage. As a result, an approximate value of fuel consumed in actual traveling can be displayed to provide the driver with useful fuel mileage information.

Now, an operation of the vehicle fuel mileage meter42will be described with reference to a flowchart shown inFIG. 8.

ST11: It is determined whether the ignition104is “ON.” In other words, it is determined whether the engine is started. When the answer is YES, the process proceeds to ST12, and when NO, repeats ST11.

ST12: When the ignition104is turned “ON,” the display drive controller109operates to reset the fuel mileage of the fuel mileage display43. That is, the fuel mileage (e.g., “20.5 km/l”) displayed at the previous traveling is reset.

ST13: In response to a signal supplied from the display drive controller109, the expression “Calculating Fuel mileage” is displayed on the fuel mileage display43.

ST14: With the vehicle speed as V and the predetermined speed threshold as Va (e.g., 5 km/h), it is determined whether or not the vehicle speed V exceeds the speed threshold Va at the speed determiner105. When the answer is YES, the process proceeds to ST15, and when no, repeats ST14.

ST15: Measurement of the distance traveled is started at the traveled distance calculator106.

ST16: Measurement of the amount of consumed fuel is started at the consumed fuel amount calculator107.

ST17: It is determined whether the display button45is turned “ON.” When the answer is YES, the process proceeds to ST18, and when no, the process is terminated.

ST18: Intermediate fuel mileage at the time when the display button45is turned “ON” is displayed.

ST19: It is determined whether the ignition104is “OFF.” When the answer is YES, the process proceeds to ST20, and when NO, returns to ST17.

ST20: Final fuel mileage at this driving is displayed on the fuel mileage display43as “23.0 km/l,” for example.

The embodiment has been described with the example of displaying intermediate fuel mileage by pushing the display button45as shown inFIG. 8, but is not limited thereto. It is also possible to push the display button45for reset and then again push the display button45or turn the ignition104OFF to display fuel mileage after the reset.

The embodiment has the fuel mileage meter42incorporated in the meter unit30as shown inFIG. 2but is not limited thereto. The fuel mileage meter42may be provided in any appropriate place inside the passenger compartment11other than the meter unit30.

The present disclosure relates to the subject matter of Japanese Patent Application No. 2002-202386, filed Jul. 11, 2002, the disclosure of which is expressly incorporated herein by reference in its entirety.