JPH04329316A - Liquid level indicating meter for vehicle - Google Patents

Abstract

PURPOSE:To minimize the deflect of a pointer even if liquid level fluctuates largely depending upon the running condition such as rapid acceleration and deceleration, rapid turn of a vehicle. CONSTITUTION:Even if the output voltage of a sender unit 2 fluctuates largely, a computer 3 transmits a frequency signal, which moves a pointer 17 by one deflection angle from a present indicating position, to the driving circuit 13 of a receiver unit 4, and the transmission of the frequency signal is continued for a set time, so that it is possible to minimize the deflection of the pointer 17 at the time of rapid acceleration/deceleration, and rapid turn of an automobile.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level indicator for a vehicle, such as a vehicle fuel gauge or a vehicle oil level gauge.

0002

[Prior Art] Conventionally, a fuel gauge that indicates the amount of fuel in a fuel tank, for example, has a sender unit that converts and detects the position of a float, that is, the liquid level in the fuel tank, into a voltage value. , and a receiver unit having an indicator indicating the remaining amount of fuel based on the output of the sender unit. Note that the liquid level in the fuel tank fluctuates greatly depending on driving conditions such as sudden acceleration, deceleration, and sharp turns, so the float also vibrates significantly up and down, so if the sensitivity of the receiver unit is good, the needle will swing and the I don't know where the indicated position is.

[0003] Therefore, in automobile fuel gauges, silicone oil with high viscosity (500,000 to 1,000,000 cst; centistokes) is injected into the lower part of the rotor in order to slow the movement of the rotor of the crossed coil type gauge. (Prior art A). Alternatively, there is also a device in which a computer is used to average the output from the sender unit to obtain a target value, and the pointer is driven based on this target value (Prior Art B).

0004

[Problems to be Solved by the Invention] However, in recent years, more and more automobiles are equipped with flat fuel tanks. For this reason, fluctuations in the output voltage value of the sender unit are larger than in the conventional case. For example, as shown in the graph of Figure 5 (data when the car is turning), the output voltage value when the car is stopped is about 2.20V, but when the car is turning, it changes to about 0.35V. . Therefore, as shown in the graph of FIG.
In case B, the pointer deviates significantly from the normal value of 0°, making it difficult to effectively suppress the deviation of the pointer. SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid level indicator for a vehicle that reduces the deflection of the pointer even if the liquid level fluctuates greatly due to driving conditions such as sudden acceleration/deceleration or sharp turns of the vehicle.

[0005]

[Means for Solving the Problems] The present invention includes a detection means for detecting a liquid level in a container mounted on a vehicle, and a target value obtained by averaging the liquid level detected by the detection means. The computer includes a computer that outputs a liquid level signal based on the target value, and a pointer that indicates the liquid amount at a designated position based on the liquid level signal, and the computer outputs a liquid level signal based on the target value. , a technical means is adopted in which a liquid level signal is output that moves the pointer from the current indicated position by a resolution, and the output of this liquid level signal is continued for a set time.

[0006]

[Operation] According to the present invention, when the liquid level in the container fluctuates greatly due to driving conditions such as sudden acceleration/deceleration or sharp turns of the vehicle, the liquid level detected by the detection means also fluctuates greatly. For this reason, the computer adjusts the resolution of the pointer from the current indicated position, since the target value obtained by averaging the past liquid level and the current greatly fluctuating liquid level will fluctuate more than the past target value. That is, a liquid level signal is output so as to move the pointer by the minimum controllable amount. Therefore, the pointer moves by the resolution. At this time, the computer continues to output the liquid level signal for the set time, so the pointer moves by the resolution and does not move until the set time has elapsed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The vehicle fluid level indicator of the present invention will be explained based on an embodiment shown in FIGS. 1 to 7. FIG. 1 is a diagram schematically showing a fuel gauge for an automobile. The automobile fuel gauge 1 includes a sender unit 2, a computer 3, and a receiver unit 4.
Equipped with Note that 5 is a battery and 6 is a key switch.

The sender unit 2 is a detection means of the present invention, and includes a float 8 and a sliding resistance (not shown) that move according to changes in the liquid level of fuel in a fuel tank 7, which is a container mounted on an automobile. As the float 8 moves, the position of the contact that slides on the sliding resistance changes, and the electrical resistance value changes. Then, the sender unit 2 converts the change in electrical resistance value into a voltage value and sends it to the computer 3.

The computer 3 includes an A/D conversion circuit 9, a data processing circuit 10, an output setting circuit 11, and the like. The A/D conversion circuit 9 is a circuit that converts a voltage value (analog value) related to the liquid level sent from the sender unit 2 into a digital value. This A/D conversion circuit 9
The change in the voltage value of the sender unit 2 is 0V to 5V, A
In the case of an 8-bit computer 3 with a reference voltage of 5 V for the /D conversion circuit 9, the conversion is performed into a digital value obtained from xn=(vn/5)×255. For example, when vn=0V, it is converted to a digital value of 0, and when vn=5V, it is converted to a digital value of 255.

The data processing circuit 10 is a circuit that averages data to determine a target value. This target value (Fxn) is obtained by averaging the past seven digital values and the current digital value, for example (xn+xn-1+...+xn-7)/8.

The output setting circuit 11 sets the previous output value (Fn
-1) and the current target value (Fxn), and even if the difference between the two is large, the pointer 17 is compared with the previous indicated position of the pointer 17, that is, the previous output value (Fn-1). Find the output value (Fn) that can be moved by the resolution. This output value (Fn) is converted into a frequency signal (fn) as a liquid level signal as shown in Table 1 below, for example, and transmitted to the receiver unit 4.

0012

Further, after transmitting the frequency signal (fn) to the receiver unit 4, the output setting circuit 11 continues to transmit the same frequency signal (fn) for a set time (for example, 10 seconds) related to the fuel consumption rate. Note that the set time can be freely changed within this range, since the indication of the pointer 17 will not be inaccurate as long as it is earlier than the fuel consumption time of the automobile.

The receiver unit 4 includes a crossed coil type gauge 12 and a drive circuit 13. As shown in FIGS. 2 and 3, the crossed coil gauge 12 has a permanent magnet 1
A coil 15 is crossed around 4, and the magnetic field rotates a pointer 17 fixed to the end of a rotating shaft 16 fixed to a permanent magnet 14. Note that the pointer 17 is as shown in Fig. 4.
As shown in FIG.
It moves on the dial 18 displaying F (full) and E (empty) so that the deflection angle is . Also, silicone oil (viscosity of about 1,000 to 10,000 cst) is placed around the permanent magnet 14.
19 has been injected.

The drive circuit 13 has a well-known structure, and controls the amount of current flowing through the intersecting coils 15 based on the input frequency signal to move the pointer 17 with resolution (maximum deflection angle of 80°, 8b
In the case of IT computer 3, 80°/256≒0.3
1°) increments.

FIG. 7 is a flowchart showing the operation of the computer 3. Note that this flowchart is performed after the ignition switch is turned on and after initial setting is performed to drive the pointer 17 from the E position until it indicates the current remaining amount of fuel in the fuel tank 7.

First, a voltage value (analog value) related to the liquid level sent from the sender unit 2 is converted into a digital value (step S1). Continuing, for example, (xn
+xn-1+...+xn-7)/8, average the data (digital values) for 8 times to get the current target value (Fxn)
(Step S2). Subsequently, it is determined whether the previous output value and the current target value are the same value (Fn-1=Fxn) (step S3). When the values are the same (Yes), control in step S1 is performed.

[0018] In step S3, if the values are not the same (
No), the current target value is smaller than the previous output value (F
n-1>Fxn) (step S4). When Fn-1>Fxn (Yes), the pointer 17 indicates the resolution (
A liquid level signal {Fn=(Fn-1)-1} that can be decreased by one deflection angle of about 0.3° is set (step S5).

Further, in step S4, Fn-1>
When Fxn is not (No), the output value {F
n=(Fn-1)+1} (step S6), converts the output value (Fn) into a frequency signal (fn) (step S7), and transmits the frequency signal (fn) to the drive circuit 13 ( Step S8). It is determined whether a set time (for example, 10 seconds) has elapsed since the frequency level signal (fn) was transmitted (step S9). When the set time has not elapsed (No), the control in step S9 is performed, and when the set time has elapsed (Yes), the control in step S1 is performed.

The operation of this automobile fuel gauge 1 will be explained based on FIGS. 1 to 6. Generally, when a car accelerates or decelerates suddenly, makes a sudden turn, or runs on a steep slope, the level of fuel in the fuel tank 7 fluctuates greatly, and the float 8 of the sender unit 2 also vibrates greatly up and down. The output of 2 also changes greatly.

Therefore, a voltage value (vn: 0.35 V, for example) that is significantly reduced from the previous voltage value (vn-1: 2.20 V, for example) is input to the A/D conversion circuit 9 of the computer 3. Then, this input voltage value (vn) is
xn=(vn/5)×25 by A/D conversion circuit 9
5 is converted into a digital value (xn) and sent to the data processing circuit 10.

Then, in the data processing circuit 10, the current digital value (xn) is equal to the previous seven digital values (xn
-1+...+xn-7) to obtain the current target value (Fxn). Next, output setting circuit 1
1, the previous output value (Fn-1) and the current target value (Fx
n), and it is determined that the current target value (Fxn) has significantly decreased from the previous target value (Fn-1).

Even in the above-described case, the output setting circuit 11 moves the pointer 17 toward E by only the resolution (one deflection angle of about 0.3°) compared to the previous output value (Fn-1). Find the possible output value (Fn), and calculate the output value (Fn)
is converted into a frequency signal (fn) and transmitted to the drive circuit 13 of the receiver unit 4.

That is, a liquid level signal is transmitted that prevents the pointer 17 from moving several deflection angles at once. Therefore, the drive circuit 13 moves the pointer 17 by one deflection angle (approximately 0.3°) from the previous indicated position. Then, after the pointer 17 moves, the frequency signal (liquid level signal: f
By continuing to transmit n) to the drive circuit 13, the pointer 17 is held at the above-mentioned indicated position for a set time (for example, 10 seconds), so the remaining amount of fuel in the fuel tank 7 can be easily confirmed.

Therefore, even if the value of the output voltage of the sender unit 2 temporarily changes greatly, the pointer 17 does not swing significantly and moves very slowly to the indicated position at each set time. Note that if the set time for holding the indicated position is set earlier than the fuel consumption time based on the fuel consumption of the automobile, the indicated position of the pointer 17 will not deviate from the normal indicated position. Therefore, since the pointer 17 always points to a substantially normal pointing position, it is possible to provide a highly reliable automobile fuel gauge 1.

Next, an experiment to investigate the relationship between the output voltage value of the sender unit 2 and the deflection angle of the pointer 17 will be explained based on the graphs of FIG. 5 and FIG. 6. In this experiment, the output voltage value of the sender unit 2 and the pointer 1 were measured by driving in a fixed circle (circle radius of about 8 m) at a vehicle speed of 20 km/hr.
The relationship with the deflection angle of 7 was investigated. Note that the pointer 17 is set to point to point F when the output voltage value (vn) of the sender unit 2 is 4.60V, and the pointer 17 is set to point to point E when the output voltage value (vn) of the sender unit 2 is 0.35V.

In this experiment, the retention time of the frequency signal (fn) transmitted from the computer 3, that is, the set time, was set to 10 seconds, and the deflection angle of the pointer 17 from F to E was set to 80°. This is what happened when I did it.

As can be seen from the graph in FIG. 5, when the automobile continues to make constant circular turns for 50 seconds, the output voltage value of the sender unit 2 while stopped varies from about 2.2V to about 0.35V.
It decreases greatly like V. This sender unit 2
Conventional technology A and conventional technology B due to large fluctuations in the output of
It can be seen that the pointer fluctuates greatly, as shown in the graph of FIG. In contrast to these prior art A and B, in the case of this automotive fuel gauge 1, even if the output voltage value of the sender unit 2 fluctuates greatly, the deflection of the pointer 17 is maintained as shown in the graph of FIG. It can be seen that the corners are very small.

Since the automobile continues to make constant circular turns for 50 seconds, the output voltage value of the sender unit 2 also continues to change greatly for about 50 seconds, but since the set time is 10 seconds,
0/10=5 deflection angle, i.e. 5×0.31°=1.
The pointer 17 is driven only by 55 degrees, and once the fixed circular turn is completed, the pointer 17 does not swing even after that as in the prior art B. The above experiment is an example of an experiment in which a car is turning, but the same effect can be obtained when the fluid level changes during acceleration/deceleration driving or during a temporary stop on a slope. Obtainable.

(Modification) In this embodiment, the present invention was applied to an automobile fuel gauge, but the present invention can also be applied to engine cooling water, brake fluid, various oils such as engine oil, and vehicle fluids such as window washer fluid. It may also be applied to quantity indicating instruments. In this embodiment, a device in which the pointer rotates about a fulcrum is used, but a device in which the pointer moves reciprocatingly may also be used.

In this embodiment, a frequency signal is used as the liquid level signal, but an electric signal such as a voltage signal or a current signal, or an electric signal + fluid pressure signal may also be used as the liquid level signal. Further, in this embodiment, the pointer is moved by one deflection angle, but the pointer may be moved by a plurality of deflection angles.

[0032]

According to the present invention, even if the liquid level in the container fluctuates greatly due to driving conditions such as sudden acceleration/deceleration or sharp turns of the vehicle, it is possible to suppress the pointer from swinging greatly.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing a fuel gauge for an automobile.

FIG. 2 is a plan view showing a crossed coil type gauge.

FIG. 3 is a sectional view showing a crossed coil type gauge.

FIG. 4 is a plan view showing hands and a dial.

FIG. 5 is a graph showing experimental results.

FIG. 6 is a graph showing experimental results.

FIG. 7 is a flowchart showing the operation of the computer.

[Explanation of symbols]

1 Automotive fuel gauge (vehicle fluid level indicator) 2 Sender unit (detection means) 3 Computer 4 Receiver unit 7 Fuel tank (container) 17 Pointer

Claims (1)

[Claims] 1. A detection means for detecting a liquid level in a container mounted on a vehicle, a target value obtained by averaging the liquid level detected by the detection means, and a liquid level based on this target value. The computer includes a computer that outputs a level signal, and a pointer that indicates the liquid amount at a specified position based on the liquid level signal, and when the target value changes, the computer moves the pointer to the current specified position. A liquid level indicator for a vehicle, characterized in that it outputs a liquid level signal that moves the liquid level signal by a resolution, and continues outputting this liquid level signal for a set time.