JPS6131924A - Calculating method of fuel expense - Google Patents

Abstract

PURPOSE:To calculate correctly an instantaneous fuel expense by calculating the fuel injection quantity per unit time based on the time injecting a fuel actually and by calculating the running distance per unit volume of fuel quantity from the car speed which is obtd. from a speed sensor. CONSTITUTION:I/O incorporated with an A/D converter 1 takes up the necessary input data for the fuel injection control and outputs a fuel injecting signal according to the start of CPU incorporated with RAM2, which calculates a fuel expense from the data as well obtd. from a car speed sensor with calculating the fuel injection time based on the data obtd. by the I/O1. A calculation pro- cess is programmed in a memory ROM3 and a liquid crystal driving circuit 4 changes the segment of a display part 5 according to the start which is from the CPU2, which decides non-periodically the task to decide the fuel injection time at a fixed period and the task to start by the signal of a crank angle and calculates the running distance per unit fuel volume from the car speed to be obtd. from a speed sensor as well with calculating the fuel injection per unit time based on the time actually injecting a fuel. The instantaneous fuel expense can be thus calculated correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to meters for automobiles, etc., and particularly to a fuel efficiency calculation method suitable for fuel efficiency meters that display instantaneous fuel consumption.

[Background of the invention]

Conventionally, when a driver wanted to know fuel efficiency, he had to calculate the distance traveled per unit volume of fuel from changes in the remaining fuel on the fuel gauge and trip data (a certain section distance) on the odometer. This required a lot of effort for the driver to record changes in the fuel gauge, read trip data, and even make calculations. In addition, some drivers try to drive economically, and the fuel efficiency under the current driving conditions serves as a guideline for economical driving. It was almost impossible in terms of accuracy. On the other hand, although some fuel consumption counters measure the amount of fuel consumed and display the fuel consumption on a display, the present invention does not use a fuel consumption meter.

[Purpose of the invention]

An object of the present invention is to propose a calculation method for a fuel consumption meter that calculates fuel consumption under various driving conditions from the amount of fuel injected from an injector and the vehicle speed.

[Summary of the invention]

Accurately measuring the amount of fuel remaining in the fuel tank was difficult due to the shaking and tilting of the vehicle body.

Additionally, the use of measuring instruments such as fuel consumption counters could result in high costs. However, the microcomputer that controls fuel injection can determine the fuel injection time and also detect and measure the actual injection time. The amount of fuel consumed per unit time is calculated based on the smoke flow injection time actually injected, and the fuel consumption is calculated from the vehicle speed data obtained from the vehicle speed sensor.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. The engine of this embodiment is a 4-cycle, 4-cylinder engine that uses one injector. A microcomputer system for controlling fuel injection and displaying fuel consumption according to the embodiment is shown in FIG.

101 in FIG. 1 takes input data necessary for fuel injection control and converts them into digital values, and outputs a fuel injection signal in response to activation of the CPU 2. CPU2 is engineering 1
This part calculates the fuel injection time based on the data obtained in step 01, and calculates the fuel consumption by combining it with the vehicle speed data obtained from the vehicle speed sensor (not shown), and has an internal RAM. The calculation procedure is programmed in the ROM3. In the liquid crystal drive circuit 4, the display section 5 is activated according to the activation from the CPU 2.
This is the part that changes the segment of.

The CPU 2 determines the fuel injection time per cylinder at regular intervals based on input data, but the determined fuel is actually injected every time the crank angle rotates 180 degrees. Therefore, there are two tasks: a task that determines the fuel injection time at regular intervals by clock activation (here, this is called an EGI task), and a task that is activated by a signal every 180 degrees of the crank angle (here, this is called an IRQ task). Executed aperiodically.

As shown in FIG. 2, the EGI task 10 uses a clock mechanism to determine the fuel injection time every 10+os and stores the value at address TI in the internal RAMII.The IRQ task 12 starts every 180 degrees of crank angle. Internal RAM
The numeric value of the address TI in II is transferred to the register in l10f, and the engineer 101 outputs a fuel injection signal to the injector, counts the clock, and outputs an injection signal until the value in the register is reached.

Next, an example of calculating fuel consumption will be described. The actual fuel injection time is a value stored in TI in internal RAMII when the IRQ task 12 is activated.

Let this value be T.

The IRQ task 12 performs the following calculation to obtain the fuel injection amount per unit time from T.

Here, T8 is the invalid fuel injection time, N is the engine speed, k is a coefficient determined by the characteristics of the injector, etc.
The unit system is (fi/h) (fuel injection volume liters per hour).

The IRQ task 12 stores the hourly fuel volume obtained by equation (1) at address GF in internal RAMII.

The data obtained from the vehicle speed sensor is stored in a register in l101 (in a different location from the above register), and the KMPL task calculates the fuel consumption, transfers the fuel consumption data to the liquid crystal drive circuit 13, and starts the circuit. 14 will be explained. The KMPL task 14 is started every 80 m5 and calculates fuel efficiency as follows from the data stored in the GF in the internal RAM II and the vehicle speed data in the task 101.

■ □　　　　　　　　　　　　　　　...(2)G.

, where V is the vehicle speed (km/h), and V%G is also a numerical value when the KMPL task is started and read from the memory. (2) When driving with inertia without fuel injection due to overflow or fuel cut, etc. where the calculation result of formula (2) exceeds the digital bit range (
In the case of zero deband occurring in the calculation of equation (2), the maximum value of the numerical value is here taken as the calculation result of equation (2). The calculation result is stored in the register KPL of the liquid crystal drive circuit 13, and the circuit is activated.

The liquid crystal drive circuit 13 is activated every 80 m5 to change and display the liquid crystal segment according to the data in the register KPL.

In this embodiment, each function, such as a task to calculate fuel injection time, a task to start every 1808 degrees of crank angle, a task to calculate fuel consumption, etc., is distributed to tasks, each is started asynchronously, and the common memory contents are shared. This makes it easy to change each task. For example, if flickering occurs when the LCD segments change at intervals of 80m5, you can increase the startup interval of KMPL task 14, or add up the fuel efficiency calculated in KMPL 14 and average it. It is also easy to display values in arbitrary time periods.

When calculating the fuel consumption amount by integrating the fuel injection amount within a unit time, the calculated value of the fuel injection amount may deviate from the actual value due to factors such as changes in the fuel injection valve over time. To deal with this situation, measure the distance traveled and the amount of remaining fuel using the odometer and remaining fuel gauge when the vehicle is horizontally stationary, and record these values in the microcontroller.
After driving a suitable distance, the same measurement is performed again, and the cumulative fuel consumption for the driving section is calculated from the difference in surface measurement values. On the other hand, the fuel injection amount (calculated value) for the relevant travel section is accumulated, and the cumulative fuel consumption is calculated from this point on as well. If the cumulative fuel consumption calculated from the remaining fuel gauge and the cumulative fuel consumption calculated from the injection amount deviate by more than the allowable range, the microcomputer can also proportionally correct the formula for calculating the fuel injection amount using the ratio of the two. It is possible.

[Embodiments of the invention]

According to the present invention, fuel consumption can be calculated without the need for a device that measures fuel consumption, so only a conventional microcomputer that controls fuel injection and a device that has a function to display fuel consumption can be used to calculate fuel consumption depending on the driving state from moment to moment. This has the effect of having a function that accurately informs the driver of changing fuel efficiency. Since there is no need for equipment to measure fuel consumption, the cost can be reduced.

Furthermore, since the instantaneous fuel consumption can be taught to the driver, the driver can self-study the recommended driving conditions for economical driving through trial and error, which is highly effective in terms of energy saving and exhaust gas countermeasures.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a microcomputer having an engine control function and a fuel consumption display function, and FIG. 2 is an explanatory diagram of the operation of the microcomputer when calculating fuel consumption.

Claims (1)

[Claims] Fuel injection amount per unit time is determined based on the actual time of fuel injection by the fuel injection control device, which determines the fuel injection amount at a fixed cycle according to the amount of intake air per stroke of the engine and injects fuel for each stroke. A method for calculating fuel efficiency, comprising calculating an injection amount and calculating a travel distance per unit volume fuel amount from a vehicle speed obtained from a speed sensor.