JPS637609B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel gauge for an automobile that displays the amount of fuel remaining in a fuel tank.

A conventional fuel gauge of this type is shown in FIG. In FIG. 1, 1 is a fuel tank, 2 is a float 2a floating on the liquid level of fuel 1a stored in the fuel tank 1, and a sliding resistor 2b whose resistance changes according to the vertical movement of this float 2a. The main structure is a sender unit which detects the liquid level height of the fuel 1a. Reference numeral 3 mainly comprises a coil 3a whose heat generation value changes according to a change in the resistance value of the sliding resistor 2b upon receiving a signal from the sender unit 2, a bimetal 3b, and a pointer 3c which indicates the remaining amount of the fuel 1a. 4 is a key switch, and 6 is a DC power supply.

That is, in the conventional automobile fuel gauge, the float 2a provided in the sender unit 2 follows the vertical movement of the liquid level of the fuel 1a in the fuel tank 1, and the change in the resistance value of the sliding resistor 2b in conjunction with this causes the receiver to move. The bimetal 3b was deformed by changing the amount of heat generated by the coil 3a of the unit 3, and the current amount of remaining fuel was displayed by a pointer 3c that was linked to this.

Incidentally, the liquid level of the fuel 1a in the fuel tank 1 moves up and down significantly, especially when the automobile starts and stops or turns. Therefore, the sender unit 2
The resistance value of the sliding resistor 2b also fluctuates greatly, and the pointer 3c swings, making it impossible to accurately display the remaining amount of fuel.

Therefore, conventionally, in order to suppress the swinging of the pointer 3c due to the vertical movement of the liquid level of the fuel 1a, which is not based on fuel consumption,
Methods such as providing the bimetal 3b of the receiver unit 3 with a thermal time constant, or providing the pointer 3c with a braking effect using braking oil have been adopted.

However, in such a conventional automobile fuel gauge, when the key switch 4 is turned on, even though the liquid level of the fuel 1a, that is, the level of the float 2a, is stable at a constant value, due to the above-mentioned braking effect, , it takes a considerable amount of time for the pointer 3c to display the remaining amount of fuel, and similarly, when refueling the fuel tank 1 with the key switch 4 turned on, the float 2
The pointer 3c does not quickly follow the rise in a, and there is a time delay in recognizing the amount of refueling, resulting in poor responsiveness.

This invention was made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a fuel gauge for an automobile that has excellent response and braking performance and is highly accurate.

An embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a block diagram showing an embodiment of a fuel meter for an automobile according to the present invention, in which numerals 1, 2, 4 and 5 are the same as in FIG. 1, respectively. 6 calculates and processes the resistance value change signal (analog signal) from the sender unit 2, converts it into a predetermined signal format, and displays the remaining amount of fuel in the fuel tank 1 on a bar graph display 7a, a digital display 7b, etc. The arithmetic processing unit that drives the display unit 7 is composed of, for example, a microcomputer, is equipped with a digital filter, and has a variable processing time constant. Reference numeral 8 denotes a vehicle speed sensor for detecting vehicle speed, and the vehicle speed signal from this vehicle speed sensor 8 is input to the arithmetic processing unit 6, which performs the arithmetic processing using its arithmetic processing time constant as a function of the vehicle speed. be.

Next, the operation of the above-mentioned automobile fuel gauge of the present invention will be explained. That is, the arithmetic processing unit 6
The resistance value change signal from the sender unit 2 is digitally processed by a microcomputer or the like and converted into a signal format suitable for driving the display devices 7a and 7b of the display unit 7 (A/D conversion). At this time, if the resistance value change signal is faithfully followed and processed, the liquid level of the fuel 1a will change, for example, when the car starts ←
→If the vehicle moves up and down significantly when stopping or turning,
The remaining fuel amount displayed on the display unit 7 also fluctuates greatly and flickers, making it very difficult to read. However, in this invention, the vehicle speed signal from the vehicle speed sensor 8 is inputted to the arithmetic processing unit 6 together with the resistance value change signal, and during digital processing, a digital filter is provided to set the time constant as a function of the vehicle speed, for example, when the vehicle speed is 0. That is, when the vehicle is stopped, the time constant is set to 0 or a small value, and when the vehicle speed increases or is no longer 0, the time constant is set to a large value. Therefore, when refueling the fuel tank 1 (vehicle speed is 0), the display on the indicators 7a and 7b faithfully, that is, quickly follows the increase in the amount of refueling, and there is no time delay in display. In addition, even immediately after the key switch 4 is turned on (usually when the vehicle speed is 0), the indicators 7a and 7b instantly display the current fuel level,
Excellent responsiveness. In addition, fuel 1 that is not based on fuel consumption, such as when starting ←→ stopping or turning a car,
In response to the vertical movement and shaking of the liquid level at that time, the vehicle speed is usually not 0, but the arithmetic processing time constant of the arithmetic processing unit 6, here the time constant of the digital filter, is large, so the display Vessels 7a, 7b
The fuel level display does not flicker, and the braking performance is excellent.

Here, to explain the above-mentioned arithmetic processing time constant, normally, when an analog signal such as a level change of the float 2a or a resistance value change signal is A/D converted, a temporally discrete, digital amplitude value is converted. A signal with Generally, when the amplitude value of an input signal fluctuates around the true value, a digital filter is often used to deal with the situation. The effect is similar to that of analog circuits, and harmonic components can be removed from digital signals as well. Therefore,
It is also possible to set a time constant in the digital filter, and in the above embodiment, this is used as the arithmetic processing time constant in the arithmetic processing unit 6.

Note that the relationship between the time constant of the digital filter and the vehicle speed signal may be such that they are proportional to each other, or several vehicle speed regions are determined in advance and a predetermined time constant is set corresponding to each region. It is also possible to set each of them.

As described above, according to the present invention, when detecting the height of the fuel level in the fuel tank and performing calculation processing, a vehicle speed sensor is provided to detect the vehicle speed, and the vehicle speed signal from the vehicle speed sensor is processed by the calculation processing unit. Since the time constant of the calculation process is calculated as a function of the vehicle speed, when a quick response is required to display the remaining fuel level, for example, when turning on the key switch or refueling, the response is quick, and the response is slow (braking). When necessary, for example, when braking is applied while driving, the system has excellent responsiveness and braking performance, and has high display accuracy.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional automobile fuel gauge.
FIG. 2 is a block diagram showing an embodiment of an automobile fuel meter according to the present invention. DESCRIPTION OF SYMBOLS 1... Fuel tank, 1a... Fuel, 2... Sender unit, 6... Arithmetic processing unit, 7... Display unit, 8... Vehicle speed sensor. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A sender unit that detects the liquid level of fuel stored in a fuel tank, an arithmetic processing unit that arithmetic processes a signal from this sender unit and converts it into a predetermined signal format, and this arithmetic unit. In an automobile fuel meter that is driven by a signal from a processing unit and includes a display unit that displays the amount of fuel remaining in the fuel tank, a vehicle speed sensor that detects vehicle speed is provided, and the vehicle speed signal from this vehicle speed sensor is used to calculate the vehicle speed as described above. A fuel gauge for an automobile, characterized in that the time constant of the arithmetic processing is inputted to a processing unit and processed as a function of vehicle speed. 2. The fuel meter for an automobile according to claim 1, wherein the time constant of the arithmetic processing of the signal from the sender unit is made proportional to the vehicle speed. 3. The fuel meter for an automobile according to claim 1, wherein the time constant for arithmetic processing of the signal from the sender unit is made small when the vehicle speed is 0, and is made large when the vehicle speed is not 0.