Abstract:
The position of a vehicle is to be detected accurately while suppressing the consumption of a battery. In accordance with instructions given from a position detection service center a base station issues requests at certain intervals. A vehicle V, upon receipt of a request, issues an answer signal containing ID information. On the basis of the answer signal the position detection service center decides the position of the vehicle V and offers the position information to a control center on demand. Electric power is supplied from a vehicular battery to an answer signal issuing member installed in the vehicle V. Even after a main power supply switch is turned OFF, the supply of electric power from the battery is continued, thus permitting an answer to a request from the base station. Consequently, the control center can determine a vehicular stop position accurately.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2000-369883 filed on Dec. 5, 2000 the entire contents thereof is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vehicle with a position detector and more particularly to a vehicle with a position detector having a radio communication means for informing a supervisor of the position of the vehicle. 
     2. Description of Background Art 
     Systems are known for renting vehicles such as bicycles and motor-assisted bicycles. For example, in Japanese Patent Laid Open No. 142514/2000 there is described a rental system wherein an ID card issued by a central control unit is used for unlocking a motor-assisted bicycle or for replacing a battery. 
     In the above vehicle rental system, if a supervisor can detect positional information on rental vehicles, it will be useful in the operation of the rental system, including maintenance of the vehicles and accounting. 
     The use of a radio communication means may be effective for information relating to the positioning of a vehicle. In this case, however, the power consumption of the communication device used may become large, depending on the condition of radio wave. Therefore, it is necessary to avoid wasteful power consumption, or else the consumption of the battery as a power supply will be large. From this standpoint it is preferable that the transmission and reception of radio waves should be intermittent, not constant, or the power should be turned OFF when the vehicle concerned is stopped. 
     In the case of performing the transmission and reception of the radio waves intermittently, a vehicular stop position may be unable to be detected accurately at a certain difference between a power-OFF timing during vehicular stop and a position detecting timing by intermittent transmission and reception of radio wave. Therefore, it is desired to develop a system which can make an accurate position detection taking such timings into account. 
     SUMMARY AND OBJECTS OF THE INVENTION 
     In view of the above demands it is an object of the present invention to provide a vehicle with a position detector capable of transmitting a position detection signal accurately while keeping power consumption low. 
     For achieving the above-mentioned object, in a vehicle with a position detector, having a communication means which issues information to be used for deciding the position of the vehicle, the present invention permits the electric power for the communication means to be obtained from a main power supply means installed in the vehicle. A control means is provided which maintains the supply of electric power to the communication means for a predetermined time after turning OFF the main power supply means. 
     The present invention enables the time for maintaining the supply of electric power to the communication means to be set longer than an issuing interval of information to be used for deciding the position of the vehicle. 
     The present invention provides a communication means that includes a receiver means for detecting a request signal outputted at a predetermined interval from a vehicular position detecting system and a transmitter means which upon receipt of the request signal transmits the information to be used for deciding the position of the vehicle. 
     The present invention displays the information to be used for deciding the position of the vehicle on a map by the position detecting system. 
     The present invention provides that the time for maintaining the supply of electric power to the communication means is set longer than an output interval of the request signal. 
     The present invention provides a housing for removably receiving therein the communication means. The housing is provided with a contact means which fits a terminal provided on the communication means side and which is connected to the main power supply means. 
     The present invention provides an assist motor means for generating an assisting force to be added to a peddling force. A basket is disposed in a front portion of a vehicle body. The housing is fixed within the basket, and that the main power supply means is a battery used for the assist motor means. 
     The present invention provides the control means that is disposed on a bottom of the housing. The communication means is disposed on the control means, and that the housing is hermetically sealed with an upper lid. 
     According to the above features, the supply of electric power to the communication means is maintained for a preset time even after the main power supply means is turned OFF. Until the lapse of the preset time it is possible to issue information to be used for deciding the position of the vehicle. Particularly, according to the features of the present invention, information to be used for deciding the position of the vehicle can be accurately issued until interruption of the supply of electric power to the communication means. The position of the vehicle can be displayed on a map on the position detecting system side on the basis of the information to be used for deciding the position of the vehicle. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 illustrates the construction of a vehicle control system including a vehicle with a position detector according to the present invention; 
     FIG. 2 illustrates an entire construction of a motor-assisted bicycle according to an embodiment of the present invention; 
     FIG. 3 is a perspective view of a basket for goods as seen from above; 
     FIG. 4 is a partially exploded, enlarged view of a principal portion in FIG. 3; 
     FIG. 5 is an exploded perspective view of the position detector; and 
     FIG. 6 is a circuit diagram of a control unit which supplies electric power to the position detector. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described in detail with reference to the drawings. FIG. 1 illustrates the construction of a vehicle control system which includes a vehicle with a position detector according to an embodiment of the present invention. In FIG. 1, a plurality of base stations  58  are connected to a public circuit network NT. In accordance with instructions provided from a position detection service center  59  as a master station each base station  58  transmits a position information issuance request signal (request) RQ at a predetermined interval T. Upon detection of the request RQ a vehicle V issues an answer signal AQ which includes information (e.g., ID) to be used for deciding the position of the vehicle. The base station  58  which has received the answer signal AQ transfers identification information, which is allocated beforehand to the answer signal AQ-issued vehicle, to the position detection service center  59  through the public circuit network NT. On the basis of the identification information of the vehicle V thus transferred and position information of the base station  58  the position detection service center  59  regards the position of the base station  58  as the position of the vehicle V and registers it. 
     For improving the position detection accuracy for the vehicle V there can be utilized answer signals AQ to requests RQ issued from plural base stations  58 . For example, using answer signals AQ provided back from the vehicle V in reply to requests RQ issued from three base stations  58  whose positions are known, an exact vehicle position can be detected in accordance with the principle of triangulation. 
     A vehicle control center  60  is connected to another public circuit network NT 1 , which may be the same as the public circuit network NT. The vehicle control center  60  transmits, together with identification information of the vehicle V, a retrieval request PRQ inquiring of the position detection service center  59  about the position of the vehicle V through the public circuit network NT 1 . On the basis of the retrieval request PRQ and the identification information the position detection service center  59  transmits the position of the vehicle V to the vehicle control center  60  through the public circuit network NT 1 . 
     On the basis of the position information obtained from the position detection service center  59  the vehicle control center  60  can recognize the position of the vehicle V. In this case, the position of the vehicle V may be displayed on a map so that it can be easily recognized visually. Map information for the display may be provided beforehand in the vehicle control center  60  or may be acquired together with position information from the position detection service center  59 . 
     The vehicle control center  60  has a transmitting and receiving function and an image processing function for the transmission of the position information retrieving request PQ, reception of position information, and processing necessary for the display of position information received. These processings can be implemented by using a microcomputer, an image display unit such as CRT or LCD, and a memory for the storage of map information. 
     The vehicle V is provided with a position detector having a receiving function for receiving requests RQ from the base stations  58  and a transmitting function for transmitting answer signals AQ together with identification information of the vehicle in response to the requests RQ. 
     FIG. 2 is a side view of a motor-assisted bicycle as the vehicle V In FIG. 2, a body frame  2  of the motor-assisted bicycle is provided with a head pipe  21  located at a front position of a vehicle body, a down pipe  22  extending downwardly and rearwardly from the head pipe  21 , and a seat post  23  rising from near a rear end of the down pipe  22 . The connection between the down pipe  22  and the seat post  23  and the vicinity thereof are covered with a resin cover  33  which is vertically divided in two to be removably mounted. A steering handlebar  27  is connected rotatably to an upper portion of the head pipe  21  through a handlebar post  27 A, and a front fork  26 , which is steered by the steering handlebar  27 , is supported steerably by a lower portion of the head pipe  21 . A front wheel WF is rotatably supported on an axle at a lower end of the front fork  26 . 
     At a lower portion of the body frame  2  is mounted an assist motor unit  1  which includes an electric motor M for assisting a manual peddling force. A power switch  29  for the assist motor unit  1  is disposed on the down pipe  22  at a position close to the head pipe  21  so as to be turned ON and OFF with a power key. The power switch  29  may be disposed on the handlebar  27  in front of the pipe, or on the handlebar post  27 A. 
     The assist motor unit  1  is connected with screws to and suspended from three connections (not shown) which are respectively positioned at the rear end of the down pipe  22 , near a lower end of the seat post  23 , and on chain stays  25 . 
     A crank shaft  101  is rotatably supported in the assist motor unit  1  and pedals  12  are secured respectively to both right and left ends of the crank shaft  101  through cranks  11 . The chain stays  25 , which are provided in a pair right and left, extend rearwardly from the assist motor unit  1  and a rear wheel WR as a driving wheel is supported between rear ends of the chain stays  25  through an axle. A driving sprocket  13  is connected to the crank shaft  101 . The driving sprocket  13  and a rear sprocket  14  secured to the rear wheel WR are interconnected through a chain  6 . The whole of the driving sprocket  13  and an upper half of the chain  6  are covered with a chain cover  32 . 
     A pair of right and left rear upper arms  24  are disposed between an upper portion of the seat post  23  and the rear ends of both chain stays  25 . A seat pipe  31  with a seat  30  mounted on an upper end thereof is fitted in the seat post  23  so as to be vertically slidable within the seat post  23 , thus permitting adjustment of the height of the seat  30 . At a front position of the vehicle body is provided a basket  37  for goods. The basket  37  is supported by stays  36  extending upwardly from an axle  35  of the front wheel WF and also by the handlebar post  27 A. 
     A battery  4  contained in a receptacle case  5 , which is generally in the shape of rectangular parallelepiped, is installed behind the seat post  23 . The battery  4  includes a plurality of battery cells and is installed along the seat post  23  so that its longitudinal direction is approximately a vertical direction. A knob  41  is provided at an upper end in the longitudinal direction of the battery  4 . A residual charge quantity meter  42  for indicating a residual charge quantity is provided on an upper surface of the battery  4  with the knob  41  mounted thereon. Behind the battery  4  an operating lever  45  for locking and unlocking the battery  4  and a wheel locking device  100  are installed. 
     An upper portion of the receptacle case  5  is fixed with screw  39  to a bracket  40  which is fixed to each rear upper arm  24  by welding for example. The wheel locking device  100  and a rear fender  34  are also fixed with screws to the bracket  40 . 
     A lower end of the receptacle case  5  is screwed to a bracket (not shown) extending rearwardly from the seat post  23 . Moreover, a reinforcing bracket (not shown) which covers side portions of a lower end of the battery  4  is provided to prevent an external force from being exerted directly on the battery  4  through the receptacle case  5 . 
     In the assist motor unit  1 , a peddling force inputted from the crank shaft  101  and an electric assist power generated by a motor M are transmitted to the rear wheel WR via the driving sprocket  13  and the chain  6 . 
     FIG. 3 is a perspective view of the goods basket  37  as seen from above. In FIG. 3, a position detector  38  is installed at a right corner position on an inside bottom surface of the basket  37 . Thus, since the installed position of the position detector  38  is relatively high, there can be attained a satisfactory transmission/reception performance and the position detector  38  is difficult to undergo vibration and shock from the road surface, so that a high durability is ensured and maintenance and inspection are easy. The position detector  38  is bound to the basket  37  with use of a band  43 , or any other suitable fixing means, e.g. screws may be adopted. 
     FIG. 4 is a partially exploded, enlarged view of a principal portion of FIG. 3, with a lid, to be described later, of the position detector  38  being removed. A body  381  of the position detector  38  is bound together with a back lid and a control substrate, to be described later, with use of an elastic band  386  such as a cloth or rubber band and is fixed within a box  385 . 
     FIG. 5 is an exploded perspective view of the position detector  38 . In FIG. 5, the position detector  38  includes a receiving function for receiving a request RQ from each base station  58  and a transmitting function for transmitting an answer signal AQ together with identification information of the vehicle in reply to the request RQ. The position detector  38  comprises a body  381 , a body back lid  382 , and a control board  383  with a power control circuit (see FIG. 6) mounted on the back side thereof, all of which are accommodated within the box  385  equipped with a lid  384 . A power cord  44  extended from the battery  4  is drawn into the box  385  and is connected to the control board  383 . On the other hand, a cord  45  drawn out from a DC—DC converter on the control board  383  which converter will be described later is connected to the body back lid  382  with screws  46   a  and  46   b . The screws  46   a  and  46   b  are inserted through the body back lid  382  from the back side to the body  381  side. In this case, positioning is made so that the tips of the screws  46   a  and  46   b  come into abutment against power input pins  47   a  and  47   b  on the body  381  when the body  381  and the body back lid  382  are assembled together. The screws  46   a  and  46   b  constitute contact means for the supply of electric power to the position detector  38 . 
     The control board  383  is fixed with four screws  49   a  to  49   d  which are threadedly engaged with bosses  48   a  to  48   d  formed on the bottom of the box  385 . The case lid  384  is fixed to the box  385  with four screws  51   a  to  51   d  which are threadedly engaged with bosses  50   a  to  50   d  formed at four corners of the box  385 . Pawls  382   a  are formed on the lid  382 . When the lid  382  is combined with the body  381 , the pawls  382   a  come into engagement with holes  381   a  formed in the body  381 . The pawls  382   a  and the holes  381   a  are formed at a plurality of positions. It is preferable that the power cord  44  and the cord  45  are each connected to the control board  383  using a connector of a detachable type. 
     A description will now be given of a power supply circuit mounted on the control board  383 . In a circuit diagram illustrated in FIG. 6, a main switch  29  is used also as the switch of the assist motor unit  1 . A DC—DC converter  52  converts the voltage (24 volts) of the battery  4 , which is inputted through the main switch  29  and the diode  53 , to a value (4 volts) matching the supply voltage of the position detector  38  and outputs the thus-regulated voltage. The voltage thus regulated to 4 volts is applied as a supply voltage to the position detector  38  through the contacts  46   a  and  46   b  which are connected to the cord  45 . 
     A capacitor  54  is charged while the main switch  29  is ON. Upon turning OFF of the main switch  29 , the charge voltage of the capacitor  54  is applied to a timer  55 , which turns ON for a preset time to be described later. While the timer  55  is ON, a transistor  56  turns ON and a relay  57  is energized. As a result, a contact  57   a  of the relay  57  closes to maintain the input voltage to the DC—DC converter  52 . Upon turning OFF of the timer  55 , the transistor is deenergized and the contact  57   a  opens to cut off the input to the DC—DC converter  52 . Thus, even after turning OFF of the main switch  29 , the supply of electric power to the position detector  38  is maintained. 
     For example, it is preferable that the time set for the timer  55  is decided in the following manner. For a request interval T from the base stations  58 , the time set for the timer  55  is assumed to be T 1  (T&lt;T 1 ). By making such a decision, a reply can be made accurately once to a request issued from a base station  58  while the supply of electric power is continued by the timer  55 . As a result, when the main switch  29  is turned OFF, it is possible to communicate the position at which the operation of the motor-assisted bicycle is stopped or at least a position in the vicinity thereof. For example, if the request interval T is 15 minutes, the value T 1  set for the timer  55  is set to 20 minutes. 
     In the above embodiment the vehicle control center  60  searches for the position of the vehicle V through the position detection service center  59 . That is, a control system is constituted by the base stations  58 , the position detection service center  59 , and the vehicle control center  60 . However, a control system may be constituted in such a manner that the vehicle control center  60  is allowed to possess the function of the position detection service center  59 , a base station  58  is instructed to output a request RQ directly from the control center  60 , and the control center  60  receives an answer signal AQ directly from the base station  58 . Although in FIG. 1, the public circuit network NT to which the base stations  58  are connected and the public circuit network NT 1  to which the vehicle control center  60  is connected are separate networks, the base stations  58 , the vehicle control center  60 , and the position detection service center  59  may be connected to a single public circuit network. The present invention is widely applicable not only to motor-assisted vehicles but also to vehicles with a power supply such as a battery mounted thereon, e.g., electric vehicles. 
     As will be apparent from the above description, according to the present invention, information to be used for deciding the position of the vehicle can be issued for a certain period of time even after turning OFF the main power supply means, so at a vehicular stop position it is possible to issue the said information let the control system recognize the position of the vehicle. In the control system, therefore, the position of the vehicle can be recognized accurately even after the main power supply means is turned OFF, whereby the maintenance of the vehicle and accounting can be effected efficiently. 
     Particularly, according to the present invention, information to be used for deciding the position of the vehicle can be accurately issued at least once even after the main power supply means is turned OFF. 
     According to the present invention, since the communication means is detachably attached to the vehicle, it is possible to facilitate the maintenance. Further, according to the present invention, in a small-sized vehicle such as a bicycle wherein it is easy to ensure a receptacle space, the communication means and the control means can be installed easily without requiring any special space. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.