Receiver system for vehicles

A tire air pressure detection system and a remote key entry system have first and second receiver units, respectively. The first receiver unit has a change-over switch, which selectively outputs to a chassis ECU an output signal of either one of the first and second receiver units. Thus, the chassis ECU can receive any one of the output signals by only one interface.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2008-295361 filed on Nov. 19, 2008.

FIELD OF THE INVENTION

The present invention relates to a receiver system for vehicles, which processes and outputs to an electronic control unit (ECU) signals received from different transmitters, for example, a sensor transmitter of a tire air pressure detection system and a transmitter of a remote key of a remote key entry system.

It is conventional that a tire air pressure detection system and a remote key entry system in a vehicle have radio wave receiver units, respectively. The receiver units output the received signals to the corresponding ECUs. For example, a tire air pressure detection system has a receiver unit102as shown inFIG. 2, and a remote key entry system has a receiver unit112as shown inFIG. 3.

In the tire air pressure detection system, as shown inFIG. 2, a sensor transmitter101attached to a tire wheel transmits a data signal including tire air pressure-related data indicative of a detected tire air pressure or a detected tire air temperature, and the receiver unit102receives and outputs this data signal to a chassis ECU103. The chassis ECU103checks whether the detected tire air pressure is normal or not, and drives a meter104by a control area network communication (CAN) to generate an alarm indicating abnormality of the tire air pressure if the tire air pressure becomes too low. The receiver unit102includes a receiver antenna102a, a receiver circuit (RCV)102bfor receiving the signal of the sensor transmitter101, which is in a predetermined frequency band, a microcomputer (MC)102c, and an interface (I/F)102d. The microcomputer102cprocesses the signal received by the receiver circuit102b. The interface102dperforms local communications between the microcomputer102cand the chassis ECU103. The chassis ECU103also has an interface103aand a microcomputer103b. The interface103aalso performs local communications between the receiver unit102and the microcomputer103b. The microcomputer103bprocesses the received signal and checks whether the tire air pressure is normal or abnormal based on the received signal.

In the remote key entry system, as shown inFIG. 3, a key transmitter111attached to a remote control key (remote key) transmits a door lock/unlock signal, and the receiver unit112receives and outputs this signal to a chassis ECU113. The chassis ECU113outputs a received door lock signal or door unlock signal to a door control ECU114, which in turn controls a door actuator115to lock or unlock doors. The receiver unit112includes a receiver antenna112a, a receiver circuit (RCV)112bfor receiving the signal of the key transmitter2, which is in a predetermined frequency band, a microcomputer (MC)112c, and an interface (I/F)112d. The microcomputer112cprocesses the signal received by the receiver circuit112b. The interface112dperforms local communications between the microcomputer112cand the chassis ECU113. The chassis ECU113also has an interface113aand a microcomputer113b. The interface113aalso performs local communications between the receiver unit112and the microcomputer113b. The microcomputer113bprocesses the received signal and checks whether the received signal indicates a command of door locking or door unlocking.

It is not cost-effective to separately provide the chassis ECUs103and113for the tire air pressure detection system and the remote key entry system, respectively, in a case that the receiver units102and112are provided separately. Accordingly, it is proposed to provide only one chassis ECU120for both of a tire air pressure detection system and a remote key entry system as shown inFIG. 4.

According to this receiver system shown inFIG. 4, the chassis ECU120can be shared by both systems. However, the chassis ECU120is configured to include two interfaces120aand120b. The interface120aperforms local communications with the receiver unit102of the tire air pressure detection system, and the interface120bperforms local communications with the receiver112of the remote key entry system.

JP 3789335 (US 2003/0046993 A1) proposes to provide only one receiver unit130for both of a tire air pressure detection system and a key entry system as well as only one chassis ECU120as shown inFIG. 5. In this system, if the frequency of a data signal transmitted from a sensor transmitter101of a tire air pressure detection system and the frequency of a door lock/unlock signal transmitted from a remote key entry system differ from each other, both signals can be received properly by the receiver unit130by changing over or selecting a reception frequency band of a receiver circuit130aof the receiver unit130.

However, the most appropriate positions of the receiver units differ each other between the tire air pressure detection system and the remote key entry system. In the tire air pressure detection system, in particular, the frequency of the data signal is limited to about 433 MHz in Europe and to about 315 MHz in the U.S. If the allowable signal to be used is limited to only high frequency and short wavelength as in the former case (Europe), it becomes more likely that the position (null point) of the sensor transmitter, by which the receiver unit is enabled to receive the data signal of the sensor transmitter more efficiently, is limited. For this reason, it is not always advantageous to share one receiver unit by two different systems.

SUMMARY OF EXEMPLARY EMBODIMENTS

It is therefore an object of the present exemplary embodiment to provide a receiver system for vehicles, in which an interface of an electronic control unit can be shared in a case that signals transmitted from a sensor transmitter of a tire air pressure detection system and a key transmitter of a remote key entry system are received by respective receiver units.

According to the present exemplary embodiment, a receiver system for vehicles is provided in combination with a first transmitter and a second transmitter, which transmits respective data signals. The first transmitter and the second transmitter are, for example, a tire air pressure sensor and a remote key transmitter, respectively. The receiver system comprises a first receiver unit, a second receiver unit and an electronic control unit.

The first receiver unit includes a first antenna for receiving the data signal of the first transmitter, a first receiver circuit for receiving an output signal of the first antenna corresponding to the data signal of the first transmitter, a first microcomputer for receiving an output signal of the first receiver circuit corresponding to the output signal of the first antenna, and a first interface for receiving and outputting an output signal of the first microcomputer corresponding to the output signal of the first receiver circuit.

The second receiver unit includes a second antenna for receiving the data signal of second transmitter, a second receiver circuit for receiving an output signal of the second antenna corresponding to the data signal of the second transmitter, a second microcomputer for receiving an output signal of the second receiver circuit corresponding to the output signal of the second antenna, and a second interface for receiving and outputting an output signal of the second microcomputer corresponding to the output signal of the second receiver circuit.

The electronic control unit includes a third interface for receiving the output signals of the first interface and the second interface as output signals of the first receiver unit, and the second receiver unit, and a third microcomputer for producing an output signal by processing an output signal of the third interface.

The first receiver unit includes a change-over switch, which is controllable by the first microcomputer, for selecting and transmitting one of the output signals of the first microcomputer and the second receiver unit to the electronic control unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be described in detail with reference to one embodiment, in which a receiver system for vehicles is applied to two different systems, for example, a tire air pressure detection system and a remote key entry system, in which two receiver units are provided.

Referring toFIG. 1, a receiver system for vehicles is provided for receiving radio waves of a sensor transmitter (first transmitter)1attached to a tire wheel (not shown) and a key transmitter (second transmitter)2of a key carried by a user of a vehicle (not shown). The receiver system includes first and second receiver units3and4and a chassis ECU5, which are provided in the vehicle. The chassis ECU5is connected to a door control ECU6for a door actuator8and a meter7. The chassis ECU5and the door control ECU6are control ECUs for controlling the meter7and the door actuator8, respectively.

The tire air pressure detection system is formed of the sensor transmitter1, the receiver unit3, the chassis ECU5and the meter7. The remote key entry system is formed of the key transmitter2, the receiver units3,4, the chassis ECU5, the door control ECU6and the door actuator8. The receiver system for vehicles is thus formed of the receiver units3,4, the chassis ECU5and the like.

The sensor transmitter1has a sensing part, which senses a tire air pressure and a tire air temperature and transmits a radio wave of a data signal including data indicating a sensed tire air pressure. The radio wave of the data signal transmitted by the sensor transmitter1and received by the receiver unit3is in the frequency of about 315 MHz in the U.S. and in the frequency of about 433 MHz in Europe, for example. The sensor transmitter1is attached to a rim of each tire wheel of the vehicle with its sensing part being disposed inside the tire to sense the tire air pressure and the tire air temperature. The data signal of each sensor transmitter1includes a specific identification code (ID), which is different from transmitter to transmitter, that is, different from tire wheel to tire wheel. Based on the specific ID included in the data signal, the receiver unit3checks whether the received data signal is transmitted from the subject vehicle or other vehicles and further determines the specific tire wheel to which the sensor transmitter1is attached.

The key transmitter2is manipulated by a user and transmits a radio wave of a data signal including data of a command of locking or unlocking of doors. The radio wave of the data signal transmitted by the key transmitter2and received by the receiver unit4is in the frequency of about 315 MHz, for example. The key transmitter2is integrated with an ignition key2a, which is inserted into a key cylinder to start an engine in the conventional manner. The data signal of each key transmitter2also includes a specific identification code (ID), which is different from transmitter to transmitter, that is, different from vehicle to vehicle. Based on the specific ID included in the data signal, the receiver unit4checks whether the received data signal is transmitted from the key transmitter2of the subject vehicle or other vehicles.

The receiver unit3, which receives the data signal transmitted from the sensor transmitter1, is configured with a first receiver antenna3a, a first receiver circuit3b, a first microcomputer (MC)3c, a first interface (I/F)3dand a change-over switch3e.

The receiver unit3receives the radio wave of the data signal of each sensor transmitter1through the receiver antenna3aand processes the data signal before being applied to the microcomputer3c.

The receiver circuit3breceives the data signal by the superheterodyne system for example. If the data signal is about 315 MHz as in the U.S., the receiver circuit3bmixes the received data signal of 315 MHz with the frequency of 304.3 MHz thereby to down-convert the frequency of the data signal to 10.7 MHz, which is a difference between 315 MHz and 304.3 MHz. If the data signal is about 433 MHz as in Europe, the receiver circuit3bmixes the received data signal of 315 MHz with the frequency of 422.3 MHz thereby to down-convert the frequency of the data signal to 10.7 MHz, which is a difference between 433 MHz and 422.3 MHz. The receiver circuit3bwave-detects the signal of 10.7 MHz. Thus, a plurality of data signals of different frequency bands can be received by only one receiver circuit3b.

The microcomputer3cproduces an output signal to the chassis ECU5through the change-over switch3eand the interface3d. This output signal may be a signal indicative of the detected tire air pressure or excessive or unallowable decrease (abnormality) of the detected tire air pressure. The microcomputer3cproduces a change-over signal to the change-over switch3eto control the change-over switch3e. This change-over signal may be produced based on a signal received from the chassis ECU5or at a start of power supply thereto.

For example, as one power supply system A, all electric power to the receiver unit3may be supplied from a regulated power source (positive voltage source +B) connected to a battery (not shown). Alternatively, as the other power supply system B, only electric power to the change-over switch3emay be supplied from the regulated power source and the other power to the receiver circuit3b, the microcomputer3cand the like may be supplied from an ignition (IG) power source, which is connected to the battery through the ignition switch.

In case of the power supply system A, the microcomputer3cis operative even when the ignition switch is in the off-state. Therefore, the microcomputer3cmay control the change-over switch3eby receiving from the chassis ECU5or the like a signal indicating the on/off state of the ignition switch. The power supply system A is advantageous in that the change-over switch3ecan be controlled by the microcomputer3ceven if the ignition switch is in the off-state. However, since the power is supplied continuously from the regulated power source even if the ignition switch is in the off-state, the power supply of the battery cannot be reduced.

In case of the power supply system B, the microcomputer3cbecomes operative only when the ignition switch IG is turned on. Therefore, until the ignition switch is turned on, the microcomputer3ecannot receive the signal of the chassis ECU5indicating the on/off state of the ignition switch. For this reason, the change-over switch3emay be configured to automatically take a predetermined switch position as long as the ignition switch3eis in the off-state, and the change-over switch3emay be controlled by the microcomputer3cafter the ignition switch is turned on. In this instance, change-over switch3ecannot be controlled by the microcomputer3cif the ignition switch is in the off-state. However, the power supply from the regulated power source to the receiver circuit3band the microcomputer3cis not necessitated if the ignition switch is in the off-state. As a result, the power supply from the battery can be reduced.

The interface3dis connected to the chassis ECU5via local lines9a,9bto perform local communications. Thus, the interface3doutputs the signals received through the change-over switch3eto the chassis ECU5, and inputs signals received from the chassis ECU5to the microcomputer3e.

The change-over switch3eis connected to the receiver unit4through a local line9c. The change-over switch3echanges over its switch position to select either one of the output signal produced by the microcomputer3cof the receiver unit3and the output signal applied from the receiver unit4through the local line9c, so that the selected signal is produced to the chassis ECU5through the interface3d. The change-over switch3ereceives a self-check signal from the microcomputer3cthrough a first self-check line10aconnected to the local line9c, which transmits the output signal of the receiver unit4of the remote key entry system. A signal produced from the change-over switch3eis transmitted to the microcomputer3cthrough a second self-check line10bconnected to an output line, through which the change-over switch3eapplies the signal to the interface3d. Thus, the microcomputer3cis capable of self-checking and confirming the operation of the change-over switch3e. The switch position or condition of the change-over switch3eis controlled by the switch signal SW applied from the microcomputer3c.

The receiver unit4of the remote key entry system includes a second receiver antenna4a, a second receiver circuit4b, a second microcomputer4cand a second interface4dto receive and process the radio wave of the data signal transmitted from the key transmitter2. The receiver unit4is operated with the power supply from the regulated power source (+B) so that the data signal transmitted from the key transmitter2may be received even if the ignition switch is in the off-state.

In the receiver unit4, the receiver antenna4areceives various signals including the data signal transmitted from the key transmitter2, and the receiver circuit4bprocesses the received signal and applies the processed signal to the microcomputer4c.

The receiver circuit4bis configured in the same manner as the receiver circuit3bof the tire air pressure detection system. However, the receiver circuit4bis so configured that its receivable frequency band matches the frequency band of the signal transmitted from the key transmitter2.

The microcomputer4coutputs the data signal received by the receiver circuit4band indicating a command of door lock or unlock to the change-over switch3ethrough the interface4d.

The interface4dis connected to the change-over switch3eand the chassis ECU5through the local lines9cand9dto perform local communications, respectively. The interface4dtransmits the output signals produced from the microcomputer4cto the change-over switch3eand transmits signals produced from the chassis ECU5to the microcomputer4c. The local line9bconnected to the chassis ECU5is connected to the interface3dof the receiver unit3and also to the local line9dconnected to the interface4dof the receiver unit4. As a result, the signal of the chassis ECU5is transmitted to both receiver units3and4.

The chassis ECU5includes a third interface5aand a third microcomputer5b. The interface5areceives the output signal and the like of the receiver unit3and the output signal and the like of the receiver unit4. The microcomputer5bprocesses the received output signals to produce the processed signals or data to the door control ECU6and the meter7. The chassis ECU5is connected to the door control ECU6and the meter6through an in-vehicle LAN such as CAN so that signals are communicated one another. The microcomputer5bof the chassis ECU5produces command signals, which indicate a self-check operation or a registration operation, through the interface5aat the time of self-check operation or the registration operation. The microcomputers3cand3dreceive these command signals from the chassis ECU5through the respective interfaces3dand4d.

The door control ECU6drives the door actuator8in response to the signals applied from the chassis ECU5to control locking and unlocking of doors.

The meter7displays an alarm, which indicates the detected tire air pressure or the abnormality (excessive decrease) of the detected tire air pressure in response to the signals applied from the chassis ECU5. The indication of the abnormality of the detected tire air pressure may be performed by turning on an alarm light provided in the meter7.

The operation of the embodiment configured as above is described in detail below.

It is first assumed that the ignition switch is in the off-state. In case of the power supply system A, all the parts of the receiver unit3are supplied with electric power from the regulated power source. The microcomputer3cis operative and controls the change-over switch3eby receiving from the chassis ECU5a signal indicating that the ignition switch is in the off-state. Specifically, the change-over switch3eis controlled to transmit the signal produced from the receiver unit4to the chassis ECU5. Thus, if the ignition switch is in the off-state, the door lock/unlock signal transmitted from the key transmitter2is applied to the chassis ECU5through the change-over switch3eand the interface3d, which are a part of the receiver unit3.

The chassis ECU5receives the output signal including the specific ID and compares the specific ID with a pre-registered ID thereby to check whether the data signal is from the key transmitter2authorized to the subject vehicle. If the compared IDs agree, the chassis ECU5outputs its command signal to the door control ECU6in response to the received door lock/unlock signal, so that the door control ECU6drives the door actuator8to perform locking or unlocking of the doors.

In case of the power supply system B, only the change-over switch3eis operable with the electric power from the regulated power source. As a result, the change-over switch3eis driven to connect the receiver unit4to the chassis ECU5so that the output signal from the receiver unit4is automatically transmitted to the chassis ECU5. Thus, the chassis ECU5, the door control ECU6and the door actuator8operate in the same manner as in the case of the power supply system A.

If the ignition switch is turned on, in case of any of the power supply systems A and B, the change-over switch3eis controlled by the microcomputer3cto select and transmit the output signal produced by the receiver unit3to the chassis ECU5. Thus, the data signal transmitted from the sensor transmitter1or other corresponding signals, which may indicate abnormality of the detected tire air pressure, is selected and transmitted to the chassis ECU5through the change-over switch3eand the interface3d.

The chassis ECU5determines the origin (location of the sensor transmitter1) of the output signal based on the specific ID included in the output signal and drives the meter7to indicate thereon the detected tire air pressure or abnormality of the detected tire air pressure.

At the time of self-check operation, the chassis ECU5produces the check command signal to the microcomputer3cthrough the local line9band the interface3dso that the microcomputer3cperforms the self-check operation. In the self-check operation, the microcomputer3ccontrols the change-over switch3eto select and output the output signal produced from the receiver unit4of the remote key system. That is, the change-over switch3eis driven to connect the local line9cto the interface3d. Under this condition, the microcomputer3cproduces the self-check signal to the self-check line10aso that the self-check signal may be passed to the self-check line10bthrough the change-over switch3e. The self-check signal may be a pseudo signal, which is the same as the output signal produced to the local line9cby the receiver unit4when the command signal is received from the key transmitter2.

The self-check signal passing through the change-over switch3eis returned to the microcomputer3cthrough the self-check line1013. The microcomputer3cthus checks whether the change-over switch3eis normal or abnormal by checking whether the same self-check signal transmitted through the self-check line10ais returned.

At the time of registration of the receiver units3and4, the chassis ECU5produces the command signals, which are for registering the receiver units3and4from the chassis ECU5, to microcomputers3cand4cthrough the local lines9b,9dand the interfaces3d,4d. In case the command signal is for registering the receiver unit3, the microcomputers3ccontrols the change-over switch3eto connect the microcomputer3cto the interface3das in the case to transmit the output signal produced by the microcomputer3cto the chassis ECU5, and then transmits a signal including information related to the receiver unit3to the chassis ECU5through the change-over switch3e. In case the command signal is for registering the receiver unit4, the microcomputers3ccontrols the change-over switch3eto connect the microcomputer4cto the interface3das in the case to transmit the output signal produced by the microcomputer4cto the chassis ECU5, and then transmits a signal including information related to the receiver unit4to the chassis ECU5through the change-over switch3e. The information related to the receiver units3and4are registered in the chassis ECU5.

According to the embodiment of the receiver system for vehicles, the receiver units3and4are provided separately, and the change-over switch3eis provided in one (receiver unit3) of the receiver units3and4. The change-over switch3eis controllable by the microcomputer3cto select and transmit one of the output signals of the microcomputers3cand4cso that one of the output signals of the receiver units3and4is inputted to the chassis ECU5. As a result, the output signals of the receiver units3and4can be selectively inputted to the chassis ECU5through only one interface5aof the chassis ECU5.

In sharing one ECU5by both of the receiver units3and4of different systems, one interface5aof such an ECU5can be shared by the different systems.

In the embodiment, at the self-check time, the chassis ECU5transmits the command signal for the self-check operation to the microcomputer3c, so that the change-over switch3eis controlled to select and transmit the output signal of the receiver unit4and the pseudo signal is outputted as the self-check signal, which is the same as the output signal produced by the receiver unit4in response to the door lock/unlock signal of the key transmitter2.

It is also possible in the embodiment that the change-over switch3eis controlled to select and transmit the output signal of the receiver unit3, and the pseudo signal is produced as the self-check signal, which is the same as the output signal produced in response to the data signal of the sensor transmitter1. In this instance, the pseudo signal may be inputted to the change-over switch3ethrough the self-check line10a. Alternatively, the pseudo signal may be inputted to the change-over switch3ethrough the data line DATA, which is normally used to input the data signal, by controlling the change-over switch3eto a switch condition for selecting and transmitting the output signal of the microcomputer3ceven at the self-check time.

In the embodiment, in case of the power supply system A, the on/off condition signal indicating the ignition switch condition may be applied directly to the microcomputer3cin place of applying it from the chassis ECU5to the change-over switch3e. For example, the on/off condition of the ignition switch may be checked by the microcomputer3cby supplying power of the ignition power source to the microcomputer3c.

It is noted that the two systems may be other than the tire air pressure detection system and the remote key entry system, and that the change-over switch may be provided in a receiver unit of any one of the two systems.