JPH0341770B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a pulse motor type vehicle instrument.

(Prior Art and its Problems) Pulse motor-driven instruments are increasingly being adopted as vehicle instruments that display engine speed, so-called tachometers. In such pulse motor type vehicle instruments, when the engine ignition switch is turned OFF (open) and the power is turned off, the pointer does not return to zero and stops displaying the engine speed at idling. . Therefore, by adding a backup circuit from the battery to the power supply circuit, even when the ignition switch is turned off,
Current was supplied from the battery for a certain period of time, during which time the pointer was returned to zero.

On the other hand, the conventional fuel gauge that displays the amount of fuel remaining in the fuel tank is set when the ignition switch is turned on (closed).
The fuel amount is displayed only when the ignition switch is turned off and the pointer returns to zero when the power is cut off. Therefore, in order to know the current remaining fuel amount while the vehicle is stopped, there is a problem in that the ignition switch must be turned on again. (Objective of the Invention) The present invention solves the above points. The object of the present invention is to provide a pulse motor type vehicle meter that displays the amount of fuel even when the ignition switch is turned off.

(Means for solving the problem) In order to achieve the above object, the present invention includes:
an engine rotation speed signal generation circuit that detects the engine rotation speed with a rotation sensor and outputs a control signal with a number of steps according to the detected engine rotation speed;
In a pulse motor type vehicle instrument comprising an indicator, a pulse motor that drives a pointer of the indicator, and a drive circuit that drives the pulse motor in response to the control signal, the remaining amount of fuel in the fuel tank is determined. A fuel amount sensor for detection, a remaining fuel amount signal generation circuit that converts and outputs the output of the sensor into a control signal with a corresponding number of steps, and either the remaining fuel amount signal generation circuit or the engine rotation speed signal generation circuit. a switching circuit that connects the ignition switch to the drive circuit; and the switching circuit detects the open/closed state of the ignition switch and switches to the engine rotational speed signal generating circuit when the ignition switch is closed; The present invention is configured to include a switching control circuit for switching to a fuel remaining amount signal generation circuit, and a power backup circuit for supplying power to each of the circuits for a predetermined period of time after the ignition switch changes from a closed state to an open state. It is something.

(Example) An example of the present invention will be described in detail below based on the accompanying drawings.

FIG. 1 shows the configuration of a pulse motor type vehicle meter to which the present invention is applied, and the vehicle meter has an engine rotation speed signal generation circuit A and a fuel remaining amount signal generation circuit B. The engine rotation speed signal generation circuit A is a period counting type circuit, and the engine rotation sensor (Ne sensor) 1 generates one pulse signal for each engine rotation corresponding to the engine rotation speed Ne.
This pulse signal Pn is shaped into a rectangular wave pulse signal by the waveform shaping circuit 2 and then input to the period control circuit 3. Further, the period control circuit 3 generates a reference pulse with a predetermined period (for example, 160 μs).
Output Pc ₁ and add it to counter 5.

The period control circuit 3 controls the measurement period of the input pulse Pn, and the measurement period is one period of the input pulse Pn, and the input pulse is output at regular intervals.
Outputs counting stop pulse Pa at the rising edge of Pn,
Counting start pulse Pb at the falling edge of the pulse Pa
is output and added to counter 5.

The counter 5 counts the number of reference pulses Pc ₁ inputted during the counting period, and starts counting the reference pulses Pc 1 inputted immediately after the start pulse Pb is inputted, and starts counting the reference pulses Pc ₁ inputted immediately after the start pulse Pb is inputted.
Stops counting when Pa is input, and stops pulse from when start pulse Pb is input.
Reference pulse input until Pa is input
Count the number of pulses N of Pc ₁ . The count value N of the counter 5 is input to a determination circuit 6 and a division circuit 7.

The division circuit 7 divides a constant value K (for example, 37500) by the count value N input from the counter 5 (K/
N), and outputs a signal corresponding to the division value K/N, which is applied to the determination circuit 6.

The reason why such a division circuit 7 is provided is as follows. That is, in the cycle count type circuit, when the engine speed Ne is low, one cycle of the pulse signal Pn input to the counter 5 via the cycle control circuit 3 is long, so the count value N of the reference pulse Pc ₁ is large. On the other hand, the engine speed
When Ne is high, one period of the pulse signal Pn is short, so the count value N of the reference pulse _Pc1 becomes small. In other words, since the engine speed Ne and the count value N of the reference pulse Pc ₁ are inversely proportional to each other, a period counting type circuit is usually equipped with a division circuit 7, and is calculated by dividing (constant value K) ÷ (reference value). The count value N) of the pulse _Pc1 is calculated to obtain a value K/N that is proportional to the engine speed Ne.

For example, assuming that the input signal pulse Pn is outputted as one pulse per engine revolution, and the pulse period of the reference pulse Pc ₁ is 160 μs, the pulse motor 16 that rotates the instrument needle when the engine revolution speed is 1000 rpm is 10 When setting to advance in steps, one period of the signal pulse Pn input to counter 5 at this time is 60 ms, and the count value N of counter 5 is expressed as (60 ms) ÷ (160 μs) = 375. The following formula holds.

(Constant value K)÷375=10 (1) From this equation (1), it can be seen that the constant value K should be set to 3750.

By the way, in the division circuit 7 where the constant value K (=3750) is set, when the engine speed is 6000 rpm, one period of the input signal pulse pn is 10 ms, and the count value N is (10 ms) ÷ (160 μs) ≒ 62 (counts). value N
can only take integer values), and the output K/N of the divider circuit 7 is 3750÷62≒60 (this result also only takes integer values)
Therefore, the pulse motor can move up to 60 steps, and rotates to six times the position compared to when the engine speed is 1000 rpm.

The determination circuit 6 determines the status of the input pulse Pn based on the count value N input from the counter 5, that is,
It is determined whether the engine rotational speed Ne is low and the period of the input pulse Pn is long, or whether the engine rotational speed Ne is high and the period of the input pulse Pn is short. K/
The N or 0 value is output as a control signal for the number of steps S of the pulse motor 16 (hereinafter referred to as S value). That is, the determination circuit 6 determines the count value N of the reference pulse _Pc1 .
and the set value Nc, for example, the value 1024, N≧Nc (=
1024), it is determined that the engine rotation speed Ne is low and a zero value is output to the switching circuit 25.
The count value N of reference pulse Pc ₁ is the set value Nc (=
1024) is equal to the number A of pulses Pn input per minute, and this input pulse number A is A = 60 (sec) / 1024 × 160 (μsec) = 366 ... (2 ), and the engine speed Ne is 366 (rpm).

Then, when the count value N is smaller than the set value Nc (N<Nc), the judgment circuit 6 uses a division circuit 7
The division value K/N inputted from the switch circuit 25 is output to the switching circuit 25.

On the other hand, as is well known, the fuel amount sensor (FUEL sensor) 31 is composed of a variable resistor whose resistance value changes by a float that moves up and down in accordance with the height of the fuel liquid level in the fuel tank. The corresponding resistance value is set. Further, the remaining fuel amount signal generation circuit B is configured as follows. The input circuit 32 converts the change in the resistance value of the fuel amount sensor 31 corresponding to the change in the fuel amount into a voltage change, and outputs the voltage V _F to the comparison circuit 33.

The timing pulse generation circuit 34 includes a plurality of, for example, 5 timing pulse generation circuits.
outputs timing pulses _P1 to _P5 . D-
The A conversion circuit 36 inputs the timing pulses P ₁ to P ₅ outputted from the timing pulse generation circuit 34 via the output buffer circuit 35, and changes the timing pulses P ₁ to _{P 5} in a plurality of steps, for example, 32 steps. The reference voltage V _A (O, V _A1 , V _A2 ,...,
V _A31 ) (see FIG. 2) and outputs it to the comparison circuit 33. This reference voltage V _A is output at regular intervals as shown in FIG.

The comparison circuit 33 compares the voltage V _F corresponding to the amount of fuel inputted from the input circuit 32 with the reference voltage V _A inputted from the D-A conversion circuit 36, and generates a judgment signal e _F according to the result, which will be described later. The output signal is output to the conversion circuit 37 that performs the conversion. As shown in FIG. 2, this determination signal e _F is output as an "H" signal when the voltage V _F is higher than the reference voltage V _A , and as an "L" signal when it is lower. Note that when the voltage V _F is equal to the reference voltage V _A , the signal e _F may be set to be "H" or may be set to be "L".

The conversion circuit 37 receives the determination signal from the comparison circuit 33.
_eF , and also input timing pulses _P1 to _P5 from the timing pulse generation circuit 34,
First, the timing pulses P ₁ to _{P 5} when the signal e _F changes from "H" to "L" are held (stored) (see FIG. 2). Then, the held timing pulses P ₁ to _{P 5} are converted to a corresponding S value (for example,
10 to 40) and convert this S value to the switching circuit 25.
Output to.

The switching circuit 25 selectively outputs either the S value inputted from the engine rotational speed signal generating circuit A or the remaining fuel amount signal generating circuit B. The switching circuit 25 is controlled by a switching control circuit C, and the switching control circuit C is configured as follows.

The switch (SW) input circuit 26 is the switching circuit 25
This is for controlling the manual switch 2.
7 and relay switch 28 are connected in parallel, and both switches 27 and 28 are open (OFF).
, the input of the switching circuit 25 is switched to the engine rotation speed signal generation circuit A side, and when the manual switch 27 or relay switch 28 is closed (ON), the input of the switching circuit 25 is switched to the fuel remaining amount signal. Switch to generation circuit B side. The relay switch 28 is controlled to open and close by an ignition switch (IGN-SW) detection circuit 29.

The ignition switch detection circuit 29 includes:
The relay switch 28 is opened while the ignition switch IGN-SW is ON, and the relay switch 28 is closed while the ignition switch IGN-SW is OFF. Further, the detection circuit 29
is from the ignition switch IGN-SW to ON.
When turned off, the power backup circuit 11 is activated. After being activated, the power supply backup circuit 11 connects the power supply circuit 10 to a battery for a certain period of time to supply power to each circuit.

The S value output by the switching circuit 25 is the pulse motor 1.
The signal is inputted to a drive circuit D that drives and controls 7, and the drive circuit D is configured as follows. The comparison circuit 8 compares the S value inputted from the switching circuit 25 with a count value M of a counter 12, which will be described later, and provides a signal for determining whether the difference is large or small, and a signal for determining whether the count values are equal or not. It outputs the signal ea.
This large or small judgment signal ea is, for example, an "H" signal when the S value input from the switching circuit 25 is greater than the count value M of the counter 12, and an "L" signal when it is small. Output as a signal.

In addition, if the difference is equal, it may be set to "H" or may be set to "L".

Further, a determination signal is provided for determining whether or not the S value output from the switching circuit 25 and the count value M of the counter 12 are equal.
For example, if eb is equal, the signal is "L",
If not, it is output as an "H" signal.

The gate circuit 13 is opened when the signal eb output from the comparator circuit 8 is "H" when there is a difference between the S value input to the comparator circuit 8 and the count value M of the counter 12, and is used as a reference for driving the pulse motor. Reference pulse Pc ₂ continuously generated from the pulse generation circuit 14
At that time, the reference pulse Pc ₂ is input to the distribution circuit 15 and the counter 12, which will be described later, and the signal eb output when the output S of the switching circuit 25 and the count value M of the counter 12 are equal. The input of the reference pulse Pc ₂ to the distribution circuit 15 and the counter 12 is cut off.

The counter 12 consists of an up-down counter, and operates so that the count value M matches the S value inputted to the comparison circuit 8, and the large or small judgment signal ea always inputted from the comparison circuit 8 is "H". Or, by "L", a counting process of addition (up counting) or subtraction (down counting) is performed on the currently held count value for the number of reference pulses _Pc2 input. That is, when the output signal ea of the comparator circuit 8 is "H", the reference pulse Pc ₂ is applied to the gate circuit 13.
The count value of the counter 12 increases by 1 each time the signal passes through and is input, and conversely decreases by 1 when the signal is "L". Furthermore, when the S value and the count value M of the counter 10 become equal, the output signal eb of the comparator circuit 8 becomes "L".
As a result, the gate circuit 13 is closed, the reference pulse Pc ₂ from the reference pulse generation circuit 14 is not input to the counter 12, and the operation of the counter 12 is stopped. A CR circuit is connected to the front stage of the counter 12 to form a reset circuit that resets the count value to zero when the circuit power is input, so that the count value of the counter 12 always starts from zero when the vehicle is started, and the count value is set to zero when the circuit power is input. The initial operation of the meter always starts from the zero position.

Similar to the counter 12, the distribution circuit 15 is designed to always receive a large or small judgment signal ea from the comparator circuit 8, and depending on its "H" or "L", the pulse motor 16 is rotated in the normal direction. Or distribute the reference pulse Pc ₂ so as to reverse it.

That is, when the output signal ea of the comparator circuit 8 is "H", the distribution circuit 15 outputs the pulse motor 16 every time the reference pulse Pc ₂ passes through the gate circuit 13 and is input.
The reference pulse Pc ₂ is sequentially distributed in the direction of causing the pulse motor 16 to rotate forward, and conversely, when the pulse motor 16 is at "L", the reference pulse Pc ₂ is sequentially distributed in the direction of rotating the pulse motor 16 in the reverse direction.

The pointer of the indicator 17 follows the rotation of the pulse motor 16 and indicates the current engine rotation speed Ne.
The dial 18 of the indicator 17 has step numbers 0 to 100 arranged at equal intervals along the circumference as shown in FIG.
A number from 0 to 10 representing the step number is written, and inside the number, the letter E indicating fuel empty (EMPTY) is written in a position corresponding to the number 1 representing the step number 10, and a position corresponding to the number 4 representing the step number 40 is written. The letter F indicating full fuel (FULL) is written in the , the fraction character 1/2 is written in the middle position between these, and the letter E ~
The fuel remaining amount is displayed between F and F.

(Function) Next, the function of the pulse motor type vehicle meter of the present invention configured as described above will be explained.

After the ignition switch is turned on (while the vehicle is running), the manual switch 27 is operated to control the switching circuit 25, and the indicator 17 displays the engine speed using the engine speed signal generation circuit A or the remaining fuel amount signal generation circuit. It is possible to selectively display either one of the fuel amount displays B.

After the ignition switch is turned OFF (while the vehicle is stopped), the switching control circuit C switches the switching circuit 25 to the fuel remaining amount signal generation circuit B side, and the indicator 17 indicates the amount of fuel generated by the fuel remaining amount signal generation circuit B. Displays the value and holds this display value after the power is turned off.
This operation will be explained in detail with reference to FIG.

Figure 6 is a time chart before and after the ignition switch is turned off, (a) is the ON or OFF state of the ignition switch, (b) is the starting state of the power backup circuit 11, and (c) is the starting state of the power supply circuit 10. situation,
(d) shows the display state of the indicating instrument 17, and (e) shows the internal operating state of the instrument. When the ignition switch detection circuit 29 detects that the ignition switch is OFF, the power supply backup circuit 1 is activated for a predetermined period of time.
1 is started, and then the backup circuit 11 is stopped (FIGS. 6(a) and 6(b)). Therefore, the power supply circuit 10 continues to be activated for a predetermined period of time after the ignition switch is turned off until the power supply backup circuit 11 is stopped (FIG. 6(c)). While the ignition switch is ON, the indicator 17 can be selectively switched between engine rotation speed display and fuel amount display using the manual switch 27, but when the ignition switch is OFF, the indicator 17 can be switched to the relay switch 28 when the ignition switch is OFF. turns ON, and the switching circuit 25 switches the fuel display side (fuel level signal generation circuit B side)
can be switched to Inside the meter, the pulse motor 16 is driven at the predetermined time so that the indicator meter 17 indicates the current amount of fuel. After that, the internal operation of the meter stops, but the indicator 17 continues to display the current fuel amount (fuel gauge needle display) (FIGS. 6(d) and (e)).

(Effects of the Invention) As detailed above, the pulse motor type vehicle instrument of the present invention detects the engine rotation speed using a rotation sensor and outputs a control signal with a step number corresponding to the detected engine rotation speed. A pulse motor type vehicle instrument comprising a number signal generation circuit, an indicating instrument, a pulse motor that drives a pointer of the indicating instrument, and a drive circuit that drives the pulse motor in accordance with the control signal. a fuel amount sensor that detects the amount of fuel remaining in the engine; a remaining fuel amount signal generating circuit that converts the output of the sensor into a control signal with a corresponding number of steps; and the remaining fuel amount signal generating circuit or the engine rotation speed signal. a switching circuit that connects one of the generation circuits to the drive circuit; and a switching circuit that detects the open/closed state of an ignition switch and connects the switching circuit to the engine rotation speed signal generation circuit when the ignition switch is closed. a switching control circuit that switches to the remaining fuel level signal generation circuit when the ignition switch is switched or opened; and a power backup circuit that supplies power to each of the circuits for a predetermined period of time after the ignition switch changes from a closed state to an open state. Since it is equipped with the same indicator, the engine speed and fuel amount can be displayed using the same indicator, and even when the ignition switch is open, the fuel amount is displayed and maintained even when the ignition switch is not energized. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a pulse motor type vehicle meter according to the present invention, FIG. 2 is a table showing the generation of a reference voltage by timing pulses, and FIG. 3 is a time period of the reference voltage shown in FIG. Characteristic diagram, Figure 4 is a timing pulse-meter step number conversion table, Figure 5 is a diagram showing an example of the dial of the indicating instrument shown in Figure 1, Figure 6 is a diagram showing the timing pulse before and after the ignition switch is turned off. It is a time chart. A...Engine speed signal generation circuit, B...Remaining fuel amount signal generation circuit, C...Switching control circuit, D...
... Drive circuit, 1 ... Rotation sensor, 16 ... Pulse motor, 17 ... Indicator, 25 ... Switching circuit,
31...Temperature sensor.

Claims (1)

[Claims] 1. An engine rotation speed signal generation circuit that detects the engine rotation speed using a rotation sensor and outputs a control signal with a step number according to the detected engine rotation speed, an indicator, and a pulse motor that drives the pointer of the indicator. and a drive circuit that drives the pulse motor in response to the control signal, the pulse motor type vehicle instrument includes a fuel amount sensor that detects the remaining amount of fuel in the fuel tank, and an output of the sensor that corresponds to the amount of fuel remaining in the fuel tank. A remaining fuel amount signal generation circuit that converts and outputs a control signal of the number of steps; a switching circuit that connects either the remaining fuel amount signal generation circuit or the engine rotation speed signal generation circuit to the drive circuit; and the switching circuit. detecting the open/closed state of an ignition switch and switching to the engine rotation speed signal generation circuit when the ignition switch is closed;
The ignition switch includes a switching control circuit that switches to the remaining fuel level signal generation circuit when the ignition switch is opened, and a power backup circuit that supplies power to each of the circuits for a predetermined period of time after the ignition switch changes from the closed state to the open state. A pulse motor type vehicle instrument characterized by: