JP4533678B2 - In-car communication system - Google Patents

Description

  The present invention relates to an in-vehicle communication system, and more particularly to an in-vehicle communication system using an induction radio.

In recent years, there are a large number of cables such as power lines and communication lines in the vehicle, and problems such as high cost and weight increase due to these cables have occurred. In view of this, the present applicant has proposed a system that enables in-vehicle wireless communication using a cut-off frequency that is difficult to leak out of the vehicle and saves the cable in Patent Document 1 below.
JP 2003-152666 A

  However, as is well known, there are different compartments such as a trunk chamber, an engine chamber, a vehicle compartment, etc. in the vehicle. For this reason, in the case of performing wireless communication between these spaces by the system of Patent Document 1, radio waves are difficult to propagate. Even in the case of wireless communication in the same space, a propagation loss occurs in proportion to the distance between the wireless devices. That is, in the conventional in-vehicle communication system, it is difficult to communicate between different partitioned spaces or between distant places.

  Therefore, in view of the above-described present situation, an object of the present invention is to provide an in-vehicle communication system that enables wireless communication between arbitrary locations in the vehicle.

The in-vehicle communication system according to claim 1, which has been made to solve the above-described problem, includes a signal transmission path configured in a loop shape over different spaces partitioned in a vehicle, and a transmission radio wave disposed in the vehicle and transmitted to the signal transmission path. A first inductive radio device and a second inductive radio device arranged in the different spaces, which communicate via the signal transmission path, and the signal transmission path includes: It is comprised by the signal transmission line which passes through the said different space, and the body of the vehicle connected to the said signal transmission line .

According to the first aspect of the invention, by inducing a transmitted radio wave signal electrical transmission path configured to loop over different space defined at the vehicle, it is arranged in the different spaces through the signal electrical path a first inductive radio and the second induction radio has to communicate. Therefore This will allow for some propagation loss of less car radio communication between any location in the vehicle, the radio communication has been that it is difficult, the trunk room in the vehicle, the engine compartment, and communication between the cabin and the like It becomes possible. Furthermore, the car body is used as part of the signal transmission path. Therefore, it is possible to perform in-vehicle wireless communication with little propagation loss by laying a minimum signal transmission line.

The in-vehicle communication system according to claim 2, which has been made to solve the above-described problems, includes a signal transmission path configured in a loop shape over different spaces partitioned in the vehicle, and a radio wave transmitted to the signal transmission path. A first inductive radio and a second inductive radio arranged in the different space, which communicate via the signal transmission path, and the signal transmission path includes: It is composed of a wire harness disposed in the vehicle, connected to a DC drive load, and a capacitor connected to the wire harness. A switch is connected to the load, regardless of whether the switch is opened or closed. The current related to the induction radio is configured to flow through the signal transmission line.

According to the second aspect of the present invention, the transmission radio wave is induced in a signal transmission path configured in a loop shape over different spaces partitioned in the vehicle, and the first and second signals are arranged in the different spaces via the signal transmission path. The first induction radio and the second induction radio communicate with each other. Therefore, in-vehicle wireless communication with less propagation loss between any place in the vehicle is possible, and communication between the trunk room, engine room, vehicle compartment, etc. in the vehicle, which has been considered difficult for wireless communication, is also possible. become. Further, by the wire harness and a capacitor connected to a load of the DC drive as the signal electrical path is utilized without newly established signal electrical path at all, allowing small car radio communication propagation loss.

The in-vehicle communication system according to claim 3, which has been made to solve the above-mentioned problem, is the in-vehicle communication system according to claim 2 , wherein the first induction radio is the second induction radio received via the wire harness. Receiving level detecting means for detecting the receiving level of the transmission signal from the machine, and abnormality processing means for performing an abnormal process when the receiving level falls below a predetermined threshold.

According to the third aspect of the present invention, in the first induction radio device, the abnormality process is performed when the reception level from the second induction radio device is lower than the predetermined threshold value. Therefore, disconnection of the wire harness, load failure detection, and the like are possible.

According to the first aspect of the invention, by inducing a transmitted radio wave signal electrical transmission path configured to loop over different space defined at the vehicle, it is arranged in the different spaces through the signal electrical path a first inductive radio and the second induction radio has to communicate. Therefore This will allow for some propagation loss of less car radio communication between any location in the vehicle, the radio communication has been that it is difficult, the trunk room in the vehicle, the engine compartment, and communication between the cabin and the like It becomes possible. Furthermore, the car body is used as part of the signal transmission path. Therefore, it is possible to perform in-vehicle wireless communication with little propagation loss by laying a minimum signal transmission line.

According to the second aspect of the present invention, the transmission radio wave is induced in a signal transmission path configured in a loop shape over different spaces partitioned in the vehicle, and the first and second signals are arranged in the different spaces via the signal transmission path. The first induction radio and the second induction radio communicate with each other. Therefore, in-vehicle wireless communication with low propagation loss between any place in the vehicle is possible, and communication between the trunk room, engine room, vehicle compartment, etc. in the vehicle, which has been considered difficult for wireless communication, is also possible. become. Further, by the wire harness and a capacitor connected to a load of the DC drive as the signal electrical path is utilized without newly established signal electrical path at all, allowing small car radio communication propagation loss.

According to the third aspect of the present invention, in the first induction radio device, the abnormality process is performed when the reception level from the second induction radio device is lower than the predetermined threshold value. Therefore, in addition to the above effects, wire harness disconnection, load failure detection, and the like are also possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a system configuration common to the embodiments of the present invention. FIG. 2 is a block diagram showing the induction radio in FIG.

  As shown in FIG. 1, the vehicle 10 usually has different spaces partitioned into an engine compartment 10E, a vehicle compartment 10R, and a trunk compartment 10T. As is well known, an engine for driving the vehicle 10, a cooling fan, a wiper motor, and the like are arranged in the engine room 10E. Further, a control panel, seats, instruments, an air conditioner, audio equipment, and the like are arranged in the passenger compartment 10R. In the trunk room 10T, various peripheral devices such as a back monitor and an audio device are arranged.

  A loop type signal transmission path 7 is provided so as to pass through the engine compartment 10E, the vehicle compartment 10R, and the trunk compartment 10T. In addition, induction wireless devices 1, 2, and 3 are disposed in the vehicle compartment 10R, induction wireless devices 4 and 5 are disposed in the engine room 10E, and induction wireless devices 6 are disposed in the trunk chamber 10T. Yes. Each of the induction radio devices 1 to 6 is arranged while maintaining the optimum distance obtained in advance with respect to the signal transmission path 7. For example, the induction wireless device 1 (corresponding to the first induction wireless device in the claims) induces a radio wave of a predetermined radio frequency from the antenna 11 to the signal transmission path 7, and the current flowing through the signal transmission path 7 causes other It communicates with induction radios 2 to 6 (corresponding to the second induction radio in the claims).

  In addition, each device arranged in the engine compartment 10E, the vehicle compartment 10R, and the trunk compartment 10T is commanded to drive in response to a control signal from an ignition switch or a control panel in the vehicle compartment 10R. For this reason, for example, the induction wireless device 1 is connected to an ignition switch or a control panel, and other devices are connected to the other induction wireless devices 2 to 6, respectively. Then, an instruction from the ignition switch or the control panel is transmitted as a control signal from the induction wireless device 1, and this is received by the other induction wireless devices 2 to 6 through the signal transmission path 7 to control each device. . Of course, a control signal from an induction radio other than the induction radio 1 may be transmitted, or two-way communication may be performed.

  As shown in FIG. 2, each induction wireless device 1 (2 to 6) includes a loop antenna 11, an RF (radio) unit 12, a modem unit 13, a CPU 14, a memory 15, and an RSSI (received signal strength) detection unit 16. It is comprised including. Signals received by the antenna 11 and the RF unit 12 are demodulated by the modem unit 13 and a demodulated signal (received information signal) is given to the CPU 14. On the other hand, the modulation signal (information signal to be transmitted) from the CPU 14 is transmitted on the carrier wave by the modem unit 13 and transmitted from the RF unit 12 and the antenna 11. The RSSI detector 16 corresponds to the reception level detector in the claims.

  The CPU 14 is a calculation unit that performs processing as shown in FIG. 9 described later and main processing of the wireless device. The memory 15 stores at least a threshold table associated with a wireless device number and a reception level table associated with the wireless device number, which will be described later. The RSSI detection unit 16 detects the received signal strength of the received signal, that is, the reception level, and provides it to the CPU 14. Since the received signal also includes information indicating the transmission source radio number, the CPU 14 adds the radio number to the reception level and stores it in the memory 15.

FIG. 3 is a block diagram showing a system configuration as a premise of the present invention. In FIG. 3, a signal transmission line 7A is an example of the signal transmission path 7 shown in FIG. Both the induction wireless device 1A including the antenna 11A and the induction wireless device 2A including the antenna 21A have the same configuration as the induction wireless device 1 illustrated in FIG.

Generally, in order to efficiently receive the magnetic field H generated by the loop type antenna of the induction radio, it is necessary to reduce the load impedance at both ends of the signal transmission line. In other words, it is necessary to create a situation where current can easily flow through the signal transmission line. Where, it is a signal transmission line 7A to the loop type which close to 0Ω load impedance.

  By using such a signal transmission path 7, even if the distance between the induction radios 1A and 2A is more than a certain distance, the propagation loss between the induction radios 1A and 2A is a loss of coupling between the antenna and the transmission path. It can be about twice as large. With such a configuration, in-vehicle wireless communication with less propagation loss between arbitrary locations in the vehicle becomes possible. In order to further improve the reception (transmission) efficiency, a structure in which a magnetic material such as ferrite is sandwiched between the signal transmission paths may be used instead of the loop antenna.

First Embodiment
FIG. 4 is a block diagram showing the first embodiment of the present invention. In FIG. 4, a signal transmission line 7B is an example of the signal transmission path 7 shown in FIG. Specifically, the signal transmission line 7B includes a signal transmission line 7B that passes through the vehicle compartment and the trunk room, which are different compartments, and a vehicle body connected to the signal transmission line 7B. Both the induction wireless device 1B including the antenna 11B and the induction wireless device 2B including the antenna 21B have the same configuration as the induction wireless device 1 illustrated in FIG.

  As described above, by using the body of the car as a part of the signal transmission path, in-vehicle wireless communication with less propagation loss is possible only by laying the minimum signal transmission line 7B.

[ Second Embodiment]
FIG. 5A, FIG. 5B, and FIG. 5C are block diagrams showing a second embodiment of the present invention. 5A, 5B, and 5C, signal transmission lines 7C, 7D, and 7E are examples of the signal transmission path 7 illustrated in FIG. Here, the signal transmission lines 7 </ b> C, 7 </ b> D, and 7 </ b> E are, for example, wire harnesses disposed in the vehicle that are connected to a tail lamp LD that is a DC drive load. The tail lamp LD is supplied with power from the battery BT via a wire harness provided with a fuse FS, and is turned on / off by opening / closing the switch SW.

  Induction radio 1C including antenna 11C in FIG. 5A, induction radio 2C including antenna 21C, induction radio 1D including antenna 11D in FIG. 5B, induction radio 2D including antenna 21D, and The induction wireless device 1E including the antenna 11E and the induction wireless device 2E including the antenna 21E in FIG. 5C have the same configuration as the induction wireless device 1 shown in FIG. The induction radio devices 1C, 1D, and 1E and the induction radio devices 2C, 2D, and 2E are assumed to be arranged in, for example, a compartment and a trunk room, which are different spaces.

  Further, as shown in FIGS. 5A, 5B, and 5C, the signal harnesses 7C, 7D, and 7E are all provided with a capacitor C for cutting a direct current. Has been. With these capacitors C, the current related to induction radio can flow through the signal transmission lines 7C, 7D and 7E, as indicated by arrows in the figure, regardless of whether the switch SW is opened or closed.

  In this way, by using the wire harness and the capacitor connected to the DC drive load as the signal transmission path, in-vehicle wireless communication with little propagation loss can be achieved without newly establishing a signal transmission path.

[ Third embodiment]
FIG. 6A and FIG. 6B are diagrams for explaining the principle of the third embodiment of the present invention. Figure 7 shows the threshold value table according to the third embodiment of the present invention, FIG 8 is a diagram showing a reception level table according to the third embodiment of the present invention. FIG. 9 is a flowchart showing a processing procedure according to the third embodiment of the present invention.

For example, the third embodiment is based on the configuration shown in FIG. 5B, and a plurality of induction radio devices 1 to 6 are arranged in the vicinity of the loop of the signal transmission line 7D. The configuration of each induction radio 1 to 6 is, for example, as illustrated in FIG. In addition, among the induction radios 1 to 6, the induction radio 1 is connected to a control panel in the vehicle interior, and the other induction radios 2 to 6 are connected to the devices in the same room or other rooms.

  As shown in FIG. 6A, when communication is performed as described above using any two rectangular micro loop antennas 11 'in the vicinity of the signal transmission path 7' (induction radio is not shown), The coupling coefficient has a characteristic as indicated by a dotted line in FIG. 6B depending on the distance d between the two antennas 11 '. That is, it can be seen that the coupling coefficient (corresponding to the propagation loss) remains constant even when the distance d is a predetermined distance or more.

  However, as shown by the solid line in FIG. 6B, when the terminating resistance of the signal transmission path 7 ′ is ∞, that is, the signal transmission path 7 ′ is open, the coupling coefficient is also reduced in proportion to the distance d. For example, when the distance d is 1 m, the difference between the two is 30 dB or more. Using such a phenomenon, in the fourth embodiment, the disconnection of the signal transmission line (wire harness) 7D of FIG. 5B is determined.

  Prior to the determination of the disconnection of the signal transmission line 7D, the induction radio 1 detects the reception level of each induction radio 2 to 6 by the RSSI detection unit 16, and associates the threshold based on the reception level with the radio number. 7 is registered in the memory 15 as a threshold table as shown in FIG. At this stage, there is no disconnection in the signal transmission line 7D, and the induction radio 1 and the induction radios 2 to 6 and the load LD are also normal.

  As described with reference to FIG. 6, depending on the coupling coefficient, the reception levels of the induction radios 2 to 6 are not all the same, but the reception levels of the induction radios 2 to 6 are almost stable when normal. Therefore, this is registered as a threshold table as shown in FIG.

  At the time of operation, the induction radio 1 detects the reception level of each induction radio 2 to 6 at the RSSI detection unit 16 every predetermined time, and associates the result with the radio number, as shown in FIG. As a reception level table, it is updated and registered in the memory 15.

  Then, as shown in FIG. 9, the disconnection judgment is performed by comparing the reception level with the threshold value every predetermined time. That is, in step S101, the CPU 14 first sets the wireless device number to 2, and in steps S102 and S103, reads the threshold value and the reception level of the induction wireless device 2 that is the wireless device number 2 from the memory 15, respectively. Subsequently, in step S104, the CPU 14 compares the reception level with the threshold. If the reception level is equal to or lower than the threshold (N in step S104), the CPU 14 proceeds to step S105, and if the reception level is greater than the threshold (in step S104). Y), the process proceeds to step S107.

  In step S105 following N in step S104, the CPU 14 controls the RF unit 12 and the modem unit 13 to stop communication, and in step S106, performs abnormality processing related thereto. When the reception level is less than or equal to the threshold value, disconnection of the signal transmission line 7D, failure of the induction wireless device 2, and / or failure of the load LD, etc. are assumed. Command to the control panel. Steps S105 and S106 correspond to abnormality processing means in the claims.

  Further, in step S107 following Y in step S104, the CPU 14 determines whether or not the comparison processing for all the wireless devices is completed, and when the comparison processing for all the wireless devices is completed (in step S107). Y) Proceeding to step S108, the RF unit 12 and the modem unit 13 are controlled to continue communication. If the comparison processing for all the wireless devices has not been completed (N in step S107), the CPU 14 proceeds to step S109, counts up the wireless device number, and returns to step S102. In this way, the comparison processing in step S104 is performed for all the radio devices, and when an abnormality is detected in the comparison processing for any of the radio devices (N in step S104), the above steps S105 and S106 are immediately performed. Is performed.

  As shown in FIG. 8, for example, when the reception levels of the induction radios 2 to 5 with the radio numbers 2 to 5 are normal and the reception level of only the induction radio 6 is abnormal, the signal transmission line 7D The possibility that the induction radio device 6 is faulty is higher than the disconnection, and it is preferable to give an alarm to that effect. Moreover, although the example which performs a process as shown in FIG. 9 with the induction | guidance | derivation radio | wireless machine 1 was shown, you may be made to perform the same process also with the other induction | guidance | derivation radio | wireless machines 2-6.

  As described above, the configuration using the wire harness as the signal transmission line is reversely used, and disconnection of the wire harness arranged in the vehicle, load failure detection, and the like are also possible.

  As described above, according to the embodiment of the present invention, stable wireless communication can be performed between arbitrary locations in a vehicle, particularly between partitioned different spaces such as a trunk room, an engine room, a vehicle compartment, and the like. It becomes possible. In addition, since it is not necessary to wire-connect the signal transmission path and the induction radio, it is possible to easily cope with system expansion and the like only by adding the induction radio.

It is a figure which shows the system configuration common to each embodiment of this invention. It is a block diagram which shows the induction | guidance | derivation radio in FIG. It is a block diagram which shows the system configuration | structure used as the premise of this invention. 1 is a block diagram showing a first embodiment of the present invention. FIG. 5A, FIG. 5B, and FIG. 5C are block diagrams illustrating a second embodiment of the present invention. FIG. 6A and FIG. 6B are diagrams for explaining the principle of the third embodiment of the present invention. It is a figure which shows the threshold value table which concerns on 3rd Embodiment of this invention. It is a figure which shows the reception level table which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the process sequence which concerns on 3rd Embodiment of this invention.

Explanation of symbols

1-6 Induction radio 7 Signal transmission path 11 Antenna 12 RF unit 13 Modulation / demodulation unit 14 CPU
15 memory 16 RSSI detector

Claims (3)

A signal transmission path configured in a loop shape over different spaces partitioned in the vehicle,
  A vehicle interior including a first induction radio and a second induction radio arranged in the different space, arranged in the vehicle, inducing transmission radio waves in the signal transmission path and communicating via the signal transmission path A communication system,
  The signal transmission path is composed of a signal transmission line passing through the different space, and a vehicle body connected to the signal transmission line.
  An in-vehicle communication system. A signal transmission path configured in a loop shape over different spaces partitioned in the vehicle,
  A vehicle interior including a first induction radio and a second induction radio arranged in the different space, arranged in the vehicle, inducing transmission radio waves in the signal transmission path and communicating via the signal transmission path A communication system,
  The signal transmission path is composed of a wire harness disposed in a vehicle connected to a DC drive load, and a capacitor connected to the wire harness,
  A switch is connected to the load, and a current related to induction radio flows through the signal transmission line regardless of opening and closing of the switch.
  An in-vehicle communication system. The in-vehicle communication system according to claim 2 ,
The first induction radio is:
Reception level detection means for detecting a reception level of a transmission signal from the second induction radio received via the wire harness;
Abnormality processing means for performing abnormality processing when the reception level falls below a predetermined threshold,
An in-vehicle communication system.

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