JPH0217365B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid amount detection device that can quickly and accurately detect a liquid amount.

Level sensors using floats and variable resistors have been widely used in vehicle fuel calculations and the like. This level sensor changes the resistance value of a variable resistor using a float that moves up and down with the liquid level, and outputs a level voltage corresponding to the liquid level. There has conventionally been a liquid amount display device that inputs this level voltage to a plurality of comparators each having a different comparison voltage, and digitally displays the liquid amount based on the output of each comparator. For example, this display device includes four comparators and four display lamps corresponding to each comparator and arranged in parallel in the order of their comparison voltages, and lights up the display lamps corresponding to the liquid volume. . However, when such a display device is mounted on a vehicle, it is necessary to prevent the display lamp from blinking frequently in response to changes in the liquid level during driving. For this reason, in the conventional device, it was necessary to connect a delay circuit with a large time constant to the level sensor to absorb fluctuations in level voltage. Since this time constant is usually large, ranging from several tens of seconds to several minutes, it takes a long time for the level voltage to rise when the power is turned on, creating the inconvenience of having to wait a considerable amount of time for the correct display to appear.

In addition, a display device that combines a hot wire and a bimetal is widely known as a device that uses the level sensor described above, but in this case as well, it takes a considerable amount of time to heat the bimetal, so the liquid level can be accurately determined immediately after the power is turned on. The disadvantage is that it cannot be known.

The present invention was made in view of these inconveniences, and provides a liquid level display device equipped with a level sensor consisting of a float that moves up and down with the liquid level and a variable resistor that generates a level voltage in conjunction with the float. An object of the present invention is to provide a liquid level display device for a vehicle that can immediately and accurately detect the liquid level after power is turned on.

In order to achieve such an object, the present invention includes a voltage generator that repeatedly outputs a comparison voltage that decreases or increases stepwise at predetermined time intervals at a predetermined period, and compares the level voltage and the comparison voltage. and a counter that adds clock pulses based on the output of the comparator within the predetermined cycle, and is configured to display the fluid amount by the added value of the counter when the engine is stopped. be. The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a timing diagram thereof, and FIG. 3 is an explanatory diagram of its display operation. In FIG. 1, reference numeral 10 is a fuel tank for a motorcycle, and a level sensor 12 is attached to this tank 10. This level sensor 12 includes a float 14 that moves up and down with the liquid level, and a variable resistor 16 that operates in conjunction with the float, and the resistance value of the variable resistor 16 changes as the float 14 moves up and down. A current is supplied to this variable resistor 16 via a comparator 26, which will be described later, and the level voltage Vl on the anti-ground side of this variable resistor 16 decreases as the liquid level rises.

18 is a clock generator which outputs clock pulses CL at predetermined time intervals t.
(t), a clock pulse CL(T 0 ) with a period of an integer multiple thereof, e.g. 10t=T ₀ , and a clock pulse CL(T ₀ ) with a period of an integer multiple of this T ₀ , e.g. 16T ₀ = T.
Outputs CL(T).

20 is a voltage controller, and the clock pulse
The number of clock pulses between CL(T ₀ ), for example 10 clock pulses CL, in synchronization with the period of CL(T ₀ ).
A voltage selection signal is selectively sent to the ten output lines 22 every (t). A voltage generator 24 includes a constant voltage source, ten resistors with different resistance values connected in parallel to the constant voltage source, and an analog switch, which selects the voltage output by the voltage controller 20. A predetermined voltage is output via a resistor selected by a signal. Therefore, this voltage generator 24 generates a voltage that decreases stepwise through different resistors in response to a voltage selection signal sequentially output from the voltage controller 20, that is, a comparison voltage.
Outputs V _c (see Figure 2).

A comparator 26 compares the level voltage V _l and the comparison voltage V _c and outputs logic 1 while V _l <V _c . 28 is a gate circuit; 30 is a counter; gate circuit 28 is opened by the logic 1 output of comparator 26 and inputs a clock pulse CL(t) to counter 30; Counter 30 adds clock pulse CL( _t ) sent from gate 28 every period T ₀ of clock pulse CL(T 0 ). This added value, that is, the level value A, is output as a signal, for example, a 4-bit binary signal, which increases or decreases in response to increases or decreases in the liquid level. 32 is an adder which adds the level value A for a period T of the clock pulse CL(T). This period T is, for example, T=
16T ₀ is determined, and the adder 32 adds up the 16 consecutive level values A output from the counter 30, temporarily stores it in, for example, an 8-bit register, and every period T adds up the upper 4 digits in binary. The signal is output as an average level value B. In other words, since T = 16T ₀ , dividing the addition result of adder 32 by 16 = 2 ⁴ gives 16
The arithmetic mean of the 8 level values A is found, but this is equivalent to moving the contents of the 8-bit register to the lower 4-bit digits, and in the end, the upper 4 digits of this register represent the average level value B. Because it will be.

34 is a comparator, and a shift register 52 described later
Compares the display level value C stored in the display level value C with the average bell value B, and if B<C, the compressed signal a ₁ (see Figure 3) of logic 1 is used, and if B>C, the extended signal a ₂ of logic 0 is used.
Output.

36 is a compression expander, and when the comparator 34 outputs a compressed signal, a shift register 52 (described later) is used.
1 is subtracted from the display level value C of , and 1 is added to the display level C when outputting the extended signal, and these are output as the instruction level value D.

38, 40, 42, and 44 are registers, respectively. Each of the registers 38 to 44 receives each read signal b ₁ to which the register controller 46 sequentially outputs every period T.
b ₄ reads the instruction level value D or level value A in order. That is, the register controller 46
is based on the ignition system signal of the engine 48, etc.
It is determined whether the engine 48 is running or not, and if the engine is running, it outputs a running signal _c1 , and if it is stopped, it outputs a stop signal _c2 , and each register 38 to 44 outputs the running signal _c1 and each read signal. The instruction level value D is determined by b ₁ to _{b 4} , and the stop signal c ₂ and each read signal b ₁ to _{b 4}
Read the level value A.

50 is an adder, and the engine operation signal
The values stored in the registers 38 to 44 are added every cycle T based on _c1 , and the addition operation is stopped by a stop signal _c2 while the engine is stopped. Reference numeral 52 is a shift register which reads and temporarily stores the added value of the adder 50 every cycle T based on the operation signal _c1 , and also shifts the binary number by 2 digits to the lower digit to change the added value to 4=2. An operation of dividing by ² is performed, and the average of the values stored in each register 38 to 44 is output as a display level value C. This shift register 52 reads and temporarily stores the level value A of the counter 30 based on the stop signal _c2 while the engine is stopped.
To output level value A as it is as display level value C without shifting the digits.

54 is a display controller; 56 is a display device; the display controller selectively activates a large number of display segments of the display device 56 in accordance with the display level value C of the binary signal output from the shift register 52; Then, this display level value C is digitally displayed on the display 56.

Next, the operation of this embodiment will be explained. When only the power is turned on while the engine is stopped, each part of this device becomes operational, and the clock generator 18 generates clock pulses CL(t), CL(T ₀ ), and CL.
(T), while the register control circuit 46 outputs read signals b ₁ to b ₄ and an engine stop signal c ₂ . Therefore, the voltage generator 24 outputs a comparison voltage V _c that drops stepwise with a period t, while the level sensor 12 generates a level voltage V _l . comparison voltage
Since the comparator 26 outputs a logic 1 until V _c matches the level voltage V _l , the gate circuit 28 is opened and the number of clock pulses CL(t) is added up by the counter 30. The added value of the counter 30, that is, the level value, is read into the shift register 52, which is made readable by the stop signal _c2 , and is displayed on the display 56 via the display controller 54. That is, immediately after the power is turned on, the level value A is immediately displayed on the display 56, with almost no time delay. Further, the level value A is read into each register 38 to 44 by the stop signal c ₂ at each cycle T by the read signals b ₁ to b ₄ . This register 3
The level values A read from 8 to 44 become the initial values at the time of starting the engine. When the engine 48 is started, the clock controller 46 outputs the operating signal _c1 , which makes each register 38-44 ready for reading the instruction level signal D, while activating the adder 50. In addition, the shift register 52 receives this operating signal.
_C1 makes it possible to read the output of the adder 50. First, the adder 50 connects the registers 38 to 4.
Read the initial value stored in shift register 5
2. Display this initial value on the display 56 via the display controller 54. Since this initial value is equal to the level value A, the display on the display 56 does not change. On the other hand, the level value A of the counter 30 is the period of the comparison voltage _V3 .
It is added 16 times by the adder 32 every T ₀ , and the period T=
Outputs the average level value B indicated by the upper 4 digits every 16T ₀ . A comparator 34 compares the display level value C and this average level value B, and outputs a compressed signal a ₁ or an expanded signal a ₂ . When B<C, the compression expander 36 subtracts 1 from the display level value C based on the compression signal _a1 . The register 38 reads the value of C-1 by the read signal _b1 . At this time, the other register 40
.about.44 stores a level value A as the initial value, and this level value A is the same as the display level C (see FIG. 3). Each register 38-4
The stored values of 4 are added by the adder 50, and the added value (4C-1) is divided into four by the shift register, but the value below the decimal point does not appear as the display level value C. Therefore, the display level value C does not change, and the display on the display 56 also does not change. The above operations are performed for each register 40-44 in sequence.
As a result, the display on the display 56 changes at a cycle of 4T.

As described above, in this embodiment, during engine operation, the adder 32 adds the level value of the period T ₀ of the comparison voltage Vc 16 times and calculates the average. shift register 5
2, the display change is delayed to a period of 4T. Therefore, even if the liquid level changes while the vehicle is running, the display on the display will not fluctuate unstablely.

Furthermore, in this embodiment, although it is of course possible to construct each block shown in FIG.
The calculations for each block in the figure may be programmed to be performed sequentially, and this program may be stored in a predetermined memory.

As described above, this invention compares the stepped comparison voltage with the level voltage of the level sensor using a comparator, adds a clock pulse based on the output of this comparator, and uses this added value while the engine is stopped. Since the liquid volume is displayed on the display when the power is turned on, the liquid volume is immediately displayed on the display, and there is no need to wait until the display is accurate. Further, the comparison voltage has a step-like shape, and the voltage of each step portion can be set accurately by a voltage generator. For example, when the voltage generator is constructed of a constant voltage source and a plurality of resistors as in the embodiment, by accurately setting the resistance value, a comparison voltage that changes stepwise at a desired voltage can be obtained. Therefore, even if it is not possible to obtain an accurate linear relationship between the level voltage of the level sensor and the vertical position of the float, accurate liquid volume display is always possible by changing the voltage of each step of the comparison voltage. Become.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a timing diagram of a part thereof, and FIG. 3 is an explanatory diagram of display operation. 12... Level sensor, 14... Float, 1
6... Variable resistor, 24... Voltage generator, 26...
... Comparator, 30 ... Counter, 48 ... Engine, V _c ... Comparison voltage, V _l ... Level voltage.

Claims (1)

[Claims] 1 In a liquid level display device for a vehicle equipped with a level sensor consisting of a float that moves up and down with the liquid level and a variable resistor that generates a level voltage in conjunction with this float, a step-like display is displayed at predetermined time intervals. a voltage generator that repeatedly outputs a comparison voltage that decreases or increases at a predetermined period; a comparator that compares the level voltage and the comparison voltage; and a clock pulse based on the output of the comparator within the predetermined period. 1. A fluid amount display device for a vehicle, characterized in that the fluid amount display device comprises a counter that adds up the amount of water, and displays the fluid amount based on the added value of the counter when the engine is stopped.