JPS58223896A - Detector for internal pressure condition of tire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tire internal pressure state detection device that detects and displays the air pressure in tires of a running vehicle, that is, the state of the tire internal pressure.

As a conventional tire internal pressure state detection device, for example, a first
There is something like the one shown in the figure. This device is installed on the vehicle body side, &
- 1 circuit 1, a transmitting/receiving antenna 2, and a detection circuit 8 are provided, and the transmitting/receiving antenna 4, a crystal oscillator 6, and a tire internal pressure state responsive switch 6 are provided on the tire side. In this configuration, when the switch 6 is turned off depending on the tire internal pressure state, the oscillation circuit IK
When a signal with a frequency equal to the natural frequency of the crystal oscillator 6 is oscillated, the tire side circuit forms a resonant circuit, so the crystal oscillator 5 resonates through each of the transmitting and receiving antennas 2 and 4. After that, when the oscillation of the oscillation circuit 1 is stopped, the tire-side circuit starts to attenuate at the natural oscillation frequency of the crystal oscillator 5, and this damped oscillation passes through the transmitting/receiving antenna 4.2 and passes through the detection circuit 8.
Detected by Conversely, when the tire internal pressure changes and the switch 6 is closed, the tire side circuit no longer forms a resonant circuit, so even if an oscillation signal is generated from the vehicle body side oscillation circuit IK, the tire side circuit will not resonate. do not have.

Therefore, even if the oscillation circuit stops oscillating, the detection circuit 8 will not detect an attenuated signal. In this way, the tire internal pressure state is detected based on the presence or absence of the attenuation signal.

However, these conventional tire internal pressure measurement devices only have an internal pressure response switch and an associated resonant circuit with a unique imaging frequency of 1 m, so the tire internal pressure can reach a certain level. It is only possible to judge whether it is above or below, and it is not possible to continuously know the changes in internal pressure. Furthermore, the degree of danger due to a drop in tire internal pressure changes depending on the vehicle speed, and even the same internal pressure can result in a dangerous situation depending on the vehicle speed, but the above-mentioned configuration of the conventional device detects a dangerous situation depending on the vehicle speed. (There was one problem.) The present invention was made by focusing on point C during the conventional technology, and detects the tire internal pressure state at multiple levels and converts the detected internal pressure state into the vehicle speed. The purpose of this invention is to solve the above-mentioned point C by configuring the internal pressure state to generate an alarm when the internal pressure state is lower than the reference state.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 2 is a diagram showing an embodiment of the present invention.

First, to explain the configuration, the tire side has a switch 7 as a resonant circuit means that responds to the tire internal pressure state, and a fixed contact that is sequentially connected to the movable contact of the switch 7 in response to different movement amounts of the switch. , a plurality of, for example, three, crystal oscillators 8a, 8b, each having individual natural frequencies.
8c and an antenna 9 are provided so that a plurality of individual resonant circuits can be formed between the switch, the vibrator and the antenna.

Also, on the vehicle body side, a low frequency oscillator 1 is installed as an oscillation circuit means.
0, high frequency oscillator 11, crystal oscillators 12a, 12b, 1 each having a natural frequency corresponding to the natural frequency of each resonant circuit.
2c, and an antenna 18, and a scanner 14 as an oscillation switching means for sequentially controlling each resonance circuit on the tire side, and a movable contact of this scanner periodically switches the fixed contact on each crystal oscillator side. scan. In addition, a detection circuit 15 is provided as a detection element between the transmitter and the detection circuit, that is, the transmitting/receiving section and the antenna, in order to achieve impedance matching between the two.
A matching box consisting of a coil 16 and a capacitor 17 is provided. If such a good matching device is not available and the impedance between the transmitter/receiver and the antenna differs significantly, it will be difficult to detect the received waveform, and the transmitting output will have to be increased. However, when the transmission output is increased, interference occurs between wheels or between vehicles, making discrimination difficult, and also becomes a source of noise to other electrical circuit devices. Providing a matching box as in the illustrated embodiment makes it possible to suppress the transmission output to a low level and also facilitates the detection of received waves.

A comparison reference signal generation circuit 18 and a comparator 1 serve as display means for determining and displaying the tire internal pressure state based on the detection signal.
9, gate 20, series/parallel register 21, decoder 22,
A latch circuit 23 and a display element (for example LEn) 24
a, z+b are provided.

Further, this display means is provided with a vehicle speed response alarm generation means, and as this alarm generation means, a counter 25. Memory 261 for storing preset values. A comparator 27 for comparing this stored value with an actual vehicle speed value, and an alarm section 28 for issuing a warning are provided.

Next, the operation of the embodiment shown in FIG. 2 will be explained with reference to the waveform diagram of FIG. 8. A high-frequency oscillation signal that causes a resonance circuit on the tire side to resonate is generated by a high-frequency oscillator 11, and this oscillator is a crystal oscillator that oscillates at the natural frequency of a crystal resonator scanned by a scanner 14. The on/off timing of oscillation of the high frequency oscillator 11 is controlled by the output of the low frequency oscillator IO (see FIG. 8). Further, the output of the low frequency oscillator 10 of the scanner 14 is frequency-divided, and the movable contacts of the scanner 14 periodically scan the crystal oscillators 12a, 12b, and 12c in this order by a relay to switch the oscillation frequency. A time chart of this scanner switching is shown in FIG.

The internal pressure responsive switch 7 has a state in which it is connected to the fixed contacts of all the crystal cameras as shown by the solid line in FIG. 2, and a state in which it is not connected to the fixed contacts of the crystal camera as shown in the dotted line 5. It is possible to move to Assume that the switch 7 is moved and connected to the crystal oscillators 8a and 8b.

When the scanner 14 scans the crystal sensors 12a and 12b having the same natural frequency as the crystal oscillators 8a and 8b, the detection circuit 150 inputs the quotient frequency when the quotient emission is turned off (in the illustrated embodiment). Figure 3 shows the input waveform of the detector circuit for one cycle of scanner scanning when a signal with attenuation imaging is input (corresponding to the point in time when the output pulse of the low frequency oscillator reaches a high level in the example). This is the state of up to three waves from the left of the waveform. High frequency components are removed from the input signal of this detection circuit and output from the detection circuit 15 as a detection signal.

This detection signal is compared with the reference signal generated by the reference signal generation circuit 18 using a comparator 1°.The output signal of the waveform comparison 519 as shown in FIG. 3 is sent to the gate 20.
The gate is opened and closed using output pulses from a low frequency oscillator, and a gate output signal having a waveform as shown in FIG. 8 is output. In this way, the presence or absence of damped vibration is determined based on the presence or absence of pulses in the gate output signal. The output of the gate 20 is stored in the serial/parallel register 21, and the 8-bit parallel output is converted into BCD (Binary Coded) by the decoder 22.
Decimal) conversion, segment decoding,
It is held in the latch circuit 28 until one cycle of scanning is completed, and after l cycle scanning, -L is held during the next cycle of scanning.
The tire internal pressure state determined from the presence or absence of damped vibration is displayed on gD24a and 24b.

Incidentally, in the time chart shown in FIG. 8, the switch 7 is connected to the crystal oscillators 8a and 8b during the scanning of the 1st cycle, and the switch 7 is connected only to the oscillator 8a during the scanning of the second cycle.
Indicates the state when connected.

Next, the operation of the vehicle speed response warning generating means will be explained. FIG. 4 is a graph showing the relationship between the tire internal pressure and the speed at which hydroplaning occurs. As is clear from this graph, the speed of the vehicle that causes the /S hydroplaning phenomenon varies depending on the pressure condition inside the tire. Therefore, it can be seen that it is necessary to change the reference speed for issuing a warning depending on the tire internal pressure state.

The counter 25 is a counter that counts vehicle speed pulses at fixed time intervals, and the count value at a certain point in time is vo. In 718, the limit reference speed corresponding to each tire internal pressure shown in FIG. Configure to output vg. These vo and v2 are compared by the comparator 27, and 7027g
At this time, the alarm 28 is activated.

In the above example, we explained the case of hydroplaning, but since the standing wave phenomenon similarly occurs even when the road surface is dry, the vehicle speed response warning function is effective. Although a case has been shown in which eight camera elements are provided and three resonant circuits can be formed, the present invention is not limited to this, and two or eight or more crystal resonators may be provided. The greater the number, the better the resolution of internal pressure display.

Furthermore, although the resonant circuit is composed of an antenna, a crystal resonator, and K, the present invention is not limited to the crystal resonator, and the resonant circuit may be formed of a coil and a capacitor.

Furthermore, a 7-segment LED was used as a display element, but
LED strings can also be used by modifying the decoder section.

Furthermore, although the embodiment shown in FIG. 2 has been described with respect to one tire, it goes without saying that a similar device may be provided for all wheels.

As explained above, according to the present invention, there is provided a pressure-responsive switch, a plurality of resonant circuits, an oscillation circuit that sequentially oscillates these resonant circuits, a means for detecting the presence or absence of damping/damping vibration of each resonant circuit, and damping. It is composed of a display means that comprehensively determines and displays the tire internal pressure state based on the presence or absence of vibration, and a means that issues an alarm depending on the vehicle speed to determine whether or not the internal pressure state is dangerous, so it can detect multi-stage internal pressure states. can.

・Not only flat tires but also abnormal internal pressure conditions can be detected early, and the vehicle speed response warning function can prevent the occurrence of hydroplaning or standing wave phenomena, greatly improving safety. In addition to this effect, it also has the advantage of being able to detect the tire internal pressure state without contact, so there are no worn parts and excellent durability.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional tire internal pressure state detection device, Fig. 2 is a circuit diagram of an embodiment of a tire internal pressure state detection device according to the present invention, and Fig. 3 is a circuit diagram of various circuit parts in the embodiment of Fig. 2. Output waveform or state diagram, Figure 4 shows tire internal pressure and hydroplaning, s,
% * # L (D Z % fzr: yr<sf 57 "Qtp> 6.1... Launching circuit, 2,4
, 9.13... Antenna, 8.15... Detection circuit, 5.8a to 8c, 12a to 12c = crystal oscillator. 6.7... Internal pressure responsive switch, 1o... Low frequency oscillator, 11... High frequency oscillator, 14... Scanner, 1
6...Coil, l)...Capacitor, 18...Comparison reference signal generation circuit, 19.27...Comparator, 20...Gate, 21...
-Series/parallel register, 22...decoder, 28...latch circuit, 24a, 24b...display element, 25...
Counter, 26...Memory, 28...Alarm section. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] L. Resonant circuit means having a switch that responds to the internal tire pressure state of the vehicle, oscillation circuit means that generates a signal that causes the circuit of the resonant circuit means to resonate, detection means that detects the presence or absence of resonance as a detection signal, and this detection means. and a display means for determining and displaying the tire internal pressure state based on a signal 4, wherein the resonant circuit means includes a plurality of resonant circuits each having individual natural frequencies and associated with a tire internal pressure responsive switch. , the oscillation circuit means is provided with oscillation switching means for sequentially generating individual oscillation signals that cause each resonant circuit to resonate, and the display means is further provided with a display means for determining whether or not the internal pressure state is a dangerous state in response to the vehicle speed. 1. A tire internal pressure state detection device characterized in that a tire internal pressure state detection device is provided with a fast-response alarm generating means that issues a warning when the tire is in a dangerous state.