JPH01190506A - Air-pressure detecting device for automobile tire - Google Patents

Abstract

PURPOSE:To detect an air-pressure reduction of a tire easily and surely by detecting the rotating number of each tire regularly in running of an automobile, and particularly when a tire abnormally increased in rotating number in the straight running is detected, displaying this and generating an alarm. CONSTITUTION:In straight running of an automobile, as an arm 23 moving jointly with a handle shaft 22 comes close to a sensor 7, an output is generated from the sensor 7. As a result, in each circuit 10, a counter circuit 12 counts the output of a magnetic sensor 2 opposed to a magnetic disc 1. When the counted value is reached to a determined value, an FF circuit 13 is set up, and also an output is made to be generated from an AND circuit 3 to maintain the counted value in a latch circuit 14. In this case, when the air pressure of a part of the tires is reduced, the recounted value of the tire is compared with the standard value by a comparative circuit 15. If the recounted value is higher than the standard value, an alarm 9 is made to be operated through an OR circuit 8.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention provides a method for reducing air pressure in automobile tires.
The present invention relates to a device that detects and displays a degraded state.

(Prior art) There is no highly reliable, inexpensive, and easy-to-use device for detecting a drop in air pressure in an automobile tire while driving and notifying the driver, and the emergence of such a device is desired. Ta.

In particular, in cars equipped with power steering devices, even if the tire air pressure drops, it does not affect the steering operation much, so the driver can continue driving without knowing that there is an abnormal tire. Yes, it was dangerous.

(Means for Solving the Problems) Therefore, the present invention was devised to solve such problems, and in particular, in a car equipped with a plurality of tires, the air pressure of one tire is When the air pressure decreases, the average diameter of that tire becomes smaller and the rotational speed increases more than other tires with normal air pressure, so the system constantly detects the rotational speed of each tire while driving and detects abnormally high rotational speeds. When a tire is detected, it is configured to display this information and issue a warning to the driver.

(Example) As shown in Fig. 1, a disk 1 made of a magnetic material having a plurality of teeth is attached to the wheel of each tire, and a coil is attached to a permanent magnet facing the teeth of the disk L. Each magnetic sensor 2 is provided with a magnetic sensor 2 wound around the magnetic sensor 2.

Each magnetic sensor 2 is provided with a circuit 10 within a frame drawn by a dashed line.

This circuit 10 includes a waveform shaping circuit 11 that shapes the AC output of the magnetic sensor 2 into a square wave, a counting circuit 12 that counts the pulse output of this waveform shaping circuit 11, and this counting circuit 1.
A flip-flop circuit 13 that is set at the fall of the carry output that occurs during the period from when the count value of 2 reaches the full count until it returns to zero, and a latch circuit 14 that holds the count value of the counting circuit 12. , this latch circuit 1
Comparison circuit 15 compares the counted value held in 4 with the reference value from reference value generator 5 and generates an output when the counted value is larger, and displays the counted value held in latch circuit 14. The display device 1B is equipped with a display device 1B.

Furthermore, an AND circuit 3 which takes the logical product of the outputs of each flip-flop circuit 13, an OR circuit 8 which takes the logical sum of the outputs of each comparison circuit 15, and an alarm generator 9 driven by the output of this OR circuit 8. It is equipped with

The output of the AND circuit 3 is applied to the latch φ pulse input terminal of each latch circuit 14, and also applied to the clear pulse input terminal C of each counting circuit 12 via the delay circuit 4 and OR circuit 6. It is applied to the reset terminal r of the flip-flop circuit 13.

In order to detect when the automobile is traveling in a straight line without drawing a curve, an arm 23 that interlocks with the shaft 22 of the steering wheel and a sensor 7 that detects the approach of this arm 23 are provided. The output of is applied to the other input terminal of the OR circuit 6 via the inverter circuit 21.

(Function) When the car is traveling in a curve, the sensor 7 does not produce an output as shown in the waveform diagram A in FIG. Each counting circuit 12 is cleared to zero, and each flip-flop circuit 13 is reset.

When the car is traveling in a straight line, the sensor 7 generates an output and the inverter circuit 23 output disappears, so each counting circuit 12 counts the output of each magnetic sensor 2.

The count value of each counting circuit 12 is the waveform B 11°B in FIG.
12, B13, and B14, and when the count reaches the full count, a carry pulse is generated.
As shown in waveforms C11, C12, C13, and C14, the flip-flop circuits 13 are set, respectively.

When all the flip-flop circuits 13 are in the set state, an output is generated from the AND circuit 3 and each counting circuit 1
The count value of 2 is held in each latch circuit 14, and each counting circuit 12 is cleared to zero by the output of the AND circuit 3 which is delayed for a short time by the delay circuit 4. Reset.

If the air pressures of all the tires are normal and the vehicle is traveling in a straight line, the counts of each counting circuit 12 reach the full count almost simultaneously.

However, if there is a tire with reduced air pressure, the rotational speed of that tire increases, and the count value of the counting circuit 12 becomes
As shown by waveform B13 in FIG. 2, the full count is quickly reached, the flip-flop circuit 13 is set, and counting starts again from zero. When all the flip number flop circuits 13 are set, an output is generated from the AND circuit 3, and the output causes each latch circuit 14 to hold the re-counted value e of each counting circuit 12, and the re-counted value e is The numerical value e is displayed on the display 1B.

This re-counted value e is generated as a reference value in the comparator circuit 15!
! If the re-counted value e is larger than the reference value, an output is generated from the comparison circuit 15 and the alarm generator 9 is activated via the OR circuit 8.

When the car approaches a curve from a straight line and the steering wheel is operated and the arm 23 moves away from the sensor 7, an output is generated from the inverter circuit 23, and each counting circuit 12 is cleared to zero via the OR circuit 6, and each flip - Since the flop circuit 13 is reset, the alarm generator 9 will not be activated even if the rotation speeds of the left and right tires differ due to a curve.

(Other Embodiments) As shown in FIG. 3, an encoder 24 is provided which interlocks with the handle shaft 22 and generates a digital signal corresponding to the angle of the handle shaft 22.

On the other hand, a variable frequency divider 17 is provided between the waveform shaping circuit 11 and the counting circuit 12 in the circuit 10 within the frame drawn by the dashed line.
Furthermore, it includes a ROM 17 to which the output of the encoder 24 is applied to an address input, and the output of this ROM 17 is connected to a frequency division ratio setting terminal of the variable frequency divider 17.

Each ROM 17 stores the ratio of the rotation speeds of four tires with normal air pressure for each angle of the handle shaft 22.

Even if the steering wheel shaft 22 is turned and the car is traveling in a curve, the frequency division ratio corresponding to the angle of the steering wheel shaft 22 will remain in each ROM1? The number of pulses output from the four variable frequency dividers 17 is the same as long as the air pressures of the four tires are normal.

However, if there is a tire with reduced air pressure, the rotational speed of that tire will increase, and the count value of the counting circuit 12 will be
As shown by waveform B13 in FIG. 2, the full count is quickly reached.

Thereafter, the operation is similar to that of the embodiment shown in FIG. 1, and each latch circuit 14 holds the re-counted value e of the counting circuit 12, and the re-counted value e is displayed on the display 1B.
Activate the alarm generator 9.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the automobile tire air pressure drop detection device of the present invention, FIG. 2 is a waveform diagram used to explain the operation of the device shown in FIG. 1, and FIG. 2 is a block diagram showing another embodiment, and the same parts are denoted by the same reference numerals throughout the figures. 1... Magnetic disc with teeth 2... Magnetic sensor 9... Alarm generator 11... Waveform shaping circuit 12... Counting circuit 13... Flip-flop circuit

Claims (1)

[Claims] (1) Counting means for counting the number of rotations of each wheel equipped with a tire, and a method that periodically calculates the number of revolutions of each wheel equipped with a tire, and compares the smallest counted value with other counted values periodically among the counted values counted by each counting means. A device for detecting a decrease in air pressure in an automobile tire, comprising: means for obtaining a difference; and an alarm generator that issues an alarm when the difference exceeds a reference value.