JP2004330971A - Tire information detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire information detecting device capable of using a microcomputer that facilitates wiring processing of a signal cable, is inexpensive as a calculating unit, and has low processing capacity. <P>SOLUTION: Tire information output sections 11-14 comprise detecting sensors 11a-14a of tire information, and radio transmitters 11b-14b wirelessly transmitting the tire information detected by the detecting sensors to a tire information detecting section 21. The tire information detecting section 21 comprises radio receivers 21a-21d for receiving and shaping the tire information transmitted wirelessly from the radio transmitters 11b-14b and a calculating unit 21e for detecting a tire state from the tire information transmitted from the radio receivers. The radio receivers 21a-21d have a transistor 33 for controlling the output of the tire information according to the level of an RSSI output outputted from the radio receivers, and output the tire information only while the level of the RSSI output exceeds a predetermined threshold. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tire information detection device provided with a wireless transceiver, and more particularly, to a means for canceling noise transmitted from a wireless receiver.
[0002]
[Prior art]
Conventionally, an output unit (tire information output unit) for outputting a signal (tire information) including a vibration frequency component of a tire when the vehicle is traveling, and extracting a resonance frequency from a signal including the vibration frequency component of the tire, 2. Description of the Related Art There is known a tire pressure detecting device provided with a detecting means (tire information detecting unit) for detecting a state of the tire pressure based on a frequency (for example, see Patent Document 1).
[0003]
The output unit is provided corresponding to each tire of the vehicle, and outputs a signal including a detected vibration frequency component of the tire to the detection unit including a waveform shaping circuit, a ROM, a RAM, and the like. The detection means extracts a tire resonance frequency from a signal including a tire vibration frequency component output from the output means, and in a practical range of the vehicle, a change in the resonance frequency is almost caused by a change in tire pressure. The state of the air pressure for each tire is detected by utilizing the fact that it is based on a change in the constant.
[0004]
Therefore, according to this tire pressure detection device, for example, the display unit provided in the vehicle can indicate directly that the air pressure of each tire has dropped below the allowable lower limit value, or the air pressure of each tire can be displayed. By monitoring this display, it can be determined whether or not the tire pressure is normal, so that the traveling safety of the vehicle can be improved.
[0005]
[Patent Document 1]
JP-A-8-219920 (FIG. 1)
[0006]
[Problems to be solved by the invention]
By the way, in the technology described in Patent Document 1, the output means is constituted by a gear and a pickup coil which is arranged to face the cutting edge of the gear at a predetermined interval, and the pickup coil and the detection means are connected via a signal line. Connection is required, wiring processing of signal lines is required when mounting on a vehicle, and it is difficult to efficiently mount on a vehicle.
[0007]
In order to eliminate such inconvenience, a radio transmitter is provided on the output means side and a radio receiver is provided on the detection means side, and a signal including a vibration frequency component of the tire is wirelessly transmitted and received between these radio transceivers, thereby forming a signal line. Conventionally, a tire information detecting device capable of omitting wiring processing has been proposed.
[0008]
However, since noise is output from the wireless receiver due to various factors, if there is no means for canceling the noise, the load on the arithmetic unit increases, which hinders the tire information receiving process or causes an incorrect tire condition. It becomes difficult to detect the tire information, and if an arithmetic unit having a high processing capacity is provided to avoid such inconvenience, the cost of the tire information detecting device increases. Therefore, as shown in FIG. 4, the applicant of the present application previously connected the radio receivers 21a to 21d provided for each tire and the arithmetic unit 21e via a power supply line, an RSSI output line, and a tire information line. The arithmetic unit 21e monitors the level of the RSSI output from each of the radio receivers 21a to 21d, and receives the tire information by the arithmetic unit 21e only during the period when the RSSI output level exceeds a predetermined value. A tire information detecting device that starts processing is proposed.
[0009]
Since the RSSI output is output in accordance with the received signal strength of the radio receivers 21a to 21d, the waveform transmitted from the radio receivers 21a to 21d to the arithmetic unit 21e during the period when the RSSI output is low is considered to be due to noise. The waveform transmitted from the wireless receivers 21a to 21d to the arithmetic unit 21e during the period when the RSSI output is at a high level can be determined to be the desired tire information. Therefore, as shown in FIG. 5, an appropriate threshold value is set for the RSSI output, and the waveform transmitted from the wireless receivers 21a to 21d to the arithmetic unit 21e during the output period of the RSSI output exceeding the threshold value is set. If only the receiving process is executed, the waste of the receiving process in the arithmetic unit 21e can be eliminated or reduced, the load on the arithmetic unit 21e can be reduced, and the tire state can be accurately detected.
[0010]
The tire information detecting device proposed earlier by the applicant of the present application has a great effect in reducing the cost of the device as compared with the conventional technology. However, in a subsequent study, the wireless receivers 21a to 21d and the arithmetic unit 21e supply power. The number of wirings is large because they are connected via the line, the RSSI output line, and the tire information line, and there is room for improvement in this point, and output from each of the wireless receivers 21a to 21d in the arithmetic unit 21e. Since the level of the RSSI output is monitored, the burden on the arithmetic unit 21e is still large, and it has been found that there is still room for improvement in this respect.
[0011]
The present invention has been made in order to solve the deficiencies of the conventional technology, and an object of the present invention is to provide a microcomputer which can easily perform signal line wiring processing, is inexpensive as an arithmetic unit, and has low processing capability. An object of the present invention is to provide a tire information detecting device which can be used and can be implemented at a low cost.
[0012]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a tire information detecting device, a plurality of tire information output units that individually detect and output tire information of a plurality of tires attached to an axle, and the tire information. A tire information detection unit that detects a tire state of each tire from each of the tire information transmitted from the output unit, wherein the tire information output unit is a detection sensor for the tire information, and is detected by the detection sensor. A wireless transmitter that wirelessly transmits the tire information to the tire information detecting unit, wherein the tire information detecting unit performs reception and shaping of the tire information wirelessly transmitted from the wireless transmitter. An arithmetic unit for detecting the tire state from the tire information transmitted from the wireless receiver, wherein the wireless receiver is Control means for controlling the output of the tire information in accordance with the level of the input RSSI output, and outputting the tire information only during a period when the level of the RSSI output exceeds a predetermined threshold value. did.
[0013]
As described above, the wireless receiver is provided with the control means for controlling the output of the tire information in accordance with the level of the RSSI output, and when the tire information is output only during the period when the RSSI output level exceeds the predetermined threshold, the calculation is performed. The unit only needs to receive and process the tire information that does not include noise, and it is not necessary to monitor the level of the RSSI output. Therefore, the burden is reduced, and the operation unit can be reduced in cost and used with a low processing capacity. . Further, it is sufficient to connect the wireless receiver and the arithmetic unit with the power supply line and the tire information line, and the RSSI output line can be omitted, so that the wiring processing of the tire information detection unit can be simplified. Therefore, from these, the cost reduction of the tire information detecting device can be achieved.
[0014]
Further, according to the present invention, in order to solve the above-mentioned problem, in the tire information detecting device having the above-described configuration, the control unit includes a switch unit that switches at a predetermined threshold set for the RSSI output. I made it.
[0015]
As described above, if the switch unit is provided as the control unit for controlling the output of the tire information from the wireless receiver in accordance with the level of the RSSI output, the control unit can be miniaturized. The size of the tire information detection unit can be reduced.
[0016]
Further, in order to solve the above-mentioned problems, the present invention provides a tire information detection device having the above-described configuration, wherein a transistor is used as the switch means, and the base terminal, the collector terminal, and the emitter terminal of the transistor have the RSSI output terminal, The tire information output terminal of the wireless receiver is connected to the tire information input terminal of the arithmetic unit.
[0017]
As described above, when the transistor is used as the switch unit for controlling the output of the tire information from the wireless receiver according to the RSSI output level, the control unit is configured to be extremely small as compared with the case where the contact switch is used. Since the switch life can be extended and the switch life can be extended, the size of the wireless receiver and thus the tire information detecting section can be further reduced and the life can be extended.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a tire information detecting device according to the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a tire information detection device according to an embodiment, FIG. 2 is a block diagram showing a configuration of a wireless receiver and a connection system between a wireless receiver and a control unit, and FIG. FIG. 4 is a graph illustrating a relationship between an RSSI output output from a wireless receiver and an input signal of a control unit.
[0019]
As shown in FIG. 1, the tire information detecting device of the present example includes four tire information output units 11, 12, 13, and 14 provided corresponding to the four tires 1, 2, 3, and 4, respectively. And a tire information detecting unit 21 for receiving the tire information transmitted from each of the tire information output units 11, 12, 13, and 14 and detecting the tire state of each of the tires 1, 2, 3, and 4 when the vehicle is running. It is composed of Each of the tire information output units 11, 12, 13, and 14 is detected by a detection sensor 11a, 12a, 13a, 14a for detecting tire information of a corresponding tire, and the detection sensors 11a, 12a, 13a, 14a. It comprises wireless transmitters 11b, 12b, 13b, and 14b for wirelessly transmitting tire information to the tire information detector 21. The tire information detector 21 corresponds to each of the wireless transmitters 11b, 12b, 13b, and 14b. Wireless receivers 21a, 21b, 21c, and 21d for individually receiving and shaping the tire information wirelessly transmitted from the wireless transmitters 11b, 12b, 13b, and 14b; And an arithmetic unit 21e for detecting the tire condition from the information.
[0020]
It should be noted that the tire information can include various types of information on the state of the tire selected from the tire pressure, the tire rotation speed, the eccentricity of the tire with respect to the axle, the tire wear degree, the tire number, and the like. Further, the output of the tire information from the tire information output units 11, 12, 13, and 14 to the tire information detection unit 21 can be continuously performed, or intermittently at predetermined fixed time intervals, for example, every minute. You can do it too.
[0021]
As the detection sensors 11a, 12a, 13a, and 14a, appropriate ones are provided according to a detection target. In addition, as described in Japanese Patent Application Laid-Open No. 8-219920, a detection sensor for detecting tire air pressure is provided at a predetermined interval between a gear coaxially mounted on an axle and a tooth tip of the gear. And a pickup coil disposed opposite to the pickup coil.
[0022]
As shown in FIG. 2, the wireless receivers 21a, 21b, 21c, and 21d are configured to include an antenna 31, a semiconductor element 32, and a transistor 33, and are driven by receiving power from the arithmetic unit 21e. . The transistor 33 controls the output of tire information from each of the radio receivers 21a to 21d in accordance with the level of the RSSI output output from each of the radio receivers 21a to 21d. The emitter terminal is connected to the RSSI output terminal of the semiconductor element 32, the tire information output terminal of the semiconductor element 32, and the tire information input terminal of the arithmetic unit 21e. Therefore, each of the radio receivers 21a to 21d and the arithmetic unit 21e are connected via the power supply line and the tire information line, and the RSSI output line, which is an essential component in the device proposed by the applicant of the present invention, is essential. Wiring can be omitted.
[0023]
From the emitter terminal of the transistor 33, as shown in FIG. 3, only when the level of the RSSI output from the radio receivers 21a to 21d exceeds a predetermined threshold value, the tire of the arithmetic unit 21e is turned off. Tire information is output to the information input terminal. As described above, since the RSSI output is output according to the received signal strength of the radio receivers 21a to 21d, the waveform transmitted from the radio receivers 21a to 21d to the arithmetic unit 21e during the period when the RSSI output is low is The waveform can be determined to be due to noise, and the waveform transmitted from the wireless receivers 21a to 21d to the arithmetic unit 21e during the period when the RSSI output is at a high level can be determined to be the desired tire information. Therefore, as shown in FIG. 3, an appropriate threshold is set for the RSSI output, and the waveform transmitted from the wireless receivers 21a to 21d to the arithmetic unit 21e during the output period of the RSSI output exceeding the threshold is set. If only the receiving process is executed, the waste of the receiving process in the arithmetic unit 21e can be eliminated or reduced, the load on the arithmetic unit 21e can be reduced, and the tire state can be accurately detected.
[0024]
The arithmetic unit 21e performs a receiving process of the tire information transmitted from the wireless receivers 21a to 21d, detects a tire state from the received tire information, and displays a detection result on a display unit (not shown). As a result, the driver can know the condition of the tires, and can take appropriate measures such as repairing as necessary, so that safe operation of the vehicle can be achieved. When the tire information is tire pressure, the detection of the tire state can be performed by the method described in Patent Document 1.
[0025]
The tire information detection device of this example includes a transistor 33 that controls the output of tire information in accordance with the level of the RSSI output in the wireless receivers 21a to 21d, and a period in which the level of the RSSI output exceeds a predetermined threshold. Only the tire information is output, so that the arithmetic unit 21e only needs to receive and process the tire information that does not include noise, and it is not necessary to monitor the level of the RSSI output. It becomes possible to use a low arithmetic unit 21e. Further, it is only necessary to connect the radio receivers 21a to 21d and the arithmetic unit 21e with the power supply line and the tire information line, and the RSSI output line can be omitted, so that each of the radio receivers 21a constituting the tire information detection unit 21 can be omitted. To 21d and the arithmetic unit 21e can be simplified. Therefore, from these, the cost reduction of the tire information detecting device can be achieved. Furthermore, the tire information detecting device of this example includes the transistor 33 as control means for controlling the output of the tire information in the wireless receivers 21a to 21d in accordance with the level of the RSSI output. As a result, the control means can be made extremely small and the switch life can be extended, so that the radio receivers 21a to 21d, and thus the tire information detecting section 21, can be made even smaller and longer. be able to.
[0026]
In the above-described embodiment, the transistor 33 is provided in the wireless receivers 21a to 21d as control means for controlling the output of the tire information in accordance with the RSSI output level, but the gist of the present invention is not limited to this. Instead, other switch means such as a contact switch can be provided.
[0027]
【The invention's effect】
As described above, the tire information detection device of the present invention includes the wireless receiver including the control unit that controls the output of the tire information in accordance with the RSSI output level, and the RSSI output level exceeds the predetermined threshold. Since the tire information is output only in a state where the tires are in an inoperative state, the arithmetic unit only needs to receive and process only the tire information that does not include noise, and since it is not necessary to monitor the level of the RSSI output, the load on the arithmetic unit is reduced and the cost is reduced. Thus, it becomes possible to use an arithmetic unit having a low processing capacity. Further, it is sufficient to connect the wireless receiver and the arithmetic unit with the power supply line and the tire information line, and the RSSI output line can be omitted, so that the wiring processing of the tire information detection unit can be simplified. Therefore, from these, the cost reduction of the tire information detecting device can be achieved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a tire information detection device according to an embodiment.
FIG. 2 is a block diagram illustrating a configuration of a wireless receiver according to an embodiment and a connection method between the wireless receiver and a control unit.
FIG. 3 is a graph showing a relationship between an output signal of a wireless receiver, an RSSI output output from the wireless receiver, and an input signal of a control unit according to the embodiment.
FIG. 4 is a block diagram showing a connection method between a wireless receiver and a control unit according to a conventional example.
FIG. 5 is a graph showing a relationship between an RSSI output output from a wireless receiver according to a conventional example and an input signal of a control unit.
[Explanation of symbols]
1-4 Tires 11-14 Tire information output units 11a-14a Detection sensors 11b-14b Wireless transmitter 21 Tire information detectors 21a-21d Wireless receiver 21e Operation unit 31 Antenna 32 Semiconductor element 33 Transistor (control means)

Claims (3)

A plurality of tire information output units for individually detecting and outputting tire information of a plurality of tires attached to the axle, and a tire state of each tire from the respective tire information transmitted from the respective tire information output unit. And a tire information detecting unit for detecting.
The tire information output unit includes a detection sensor for the tire information, and a wireless transmitter for wirelessly transmitting the tire information detected by the detection sensor to the tire information detection unit,
The tire information detection unit is a wireless receiver that receives and shapes the tire information wirelessly transmitted from the wireless transmitter, and an operation that detects the tire state from the tire information transmitted from the wireless receiver. Consisting of units
The wireless receiver has control means for controlling the output of the tire information in accordance with the level of the RSSI output output from the wireless receiver, and the level of the RSSI output exceeds a predetermined threshold A tire information detecting device which outputs the tire information only during a period. 2. The tire information detecting device according to claim 1, wherein the control unit includes a switch unit that switches at a predetermined threshold set for the RSSI output. 3. A transistor is used as the switch means, and the RSSI output terminal, the tire information output terminal of the wireless receiver, and the tire information input terminal of the arithmetic unit are connected to a base terminal, a collector terminal, and an emitter terminal of the transistor, respectively. The tire information detecting device according to claim 2, wherein

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