Abstract:
A saddle ride type all-terrain vehicle having an engine and a saddle type driver&#39;s seat, includes a first sensor for detecting an inclination in the left-right direction of the vehicle, a second sensor for detecting an inclination in the front rear direction of the vehicle, and a controller receiving outputs from the first and second sensors, determining a tumble condition based on the outputs, and then outputting a tumble condition signal. Further, a fuel shut-off element is provided for shutting off the supply of fuel to the engine when the tumble condition signal is received from the controller.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a saddle ride type all-terrain vehicle, and particularly to a saddle ride type all-terrain vehicle including a sensor for detecting a tumbling (or roll over) of a vehicle body. 
   BACKGROUND OF THE INVENTION 
   In motorcycles having a fuel injection system, a system is provided for automatically stopping the engine by stopping the fuel pump when the vehicle has tumbled. For example, in a motorcycle described in Japanese Utility Model Publication No. Sho 60-4857, a spherical magnet is rollably placed inside a U-shaped groove formed in a non-magnetic case. The rolling of the spherical magnet in response to an inclination of the vehicle body is sensed by a reed switch, whereby the tumbling of the vehicle body is detected, and the engine is stopped. 
   Known tumble detecting sensors for a motorcycle detect when the vehicle body is inclined to either the left or right side by an amount of not less than a predetermined value. In response to this detection, the engine is stopped. In cases of motorcycles where the vehicle body may be expected to tumble to the left or right side, such a sensor detects the tumble of the vehicle body, and the engine can be stopped. In the case of a saddle ride type all-terrain vehicle (hereinafter referred to as “ATV”), on the other hand, the determination of tumble (or roll over) should be taken into account not only in the left-right direction but also in the front-rear direction, for example, when the vehicle is ascending or descending a steep slope or in like situations. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide an ATV having a sensor system capable of accurately determining a tumble (or roll over), when the vehicle is traveling on a steep slope or in like situations. 
   In order to attain the above object, the present invention is firstly characterized in that an ATV or, a saddle ride type all-terrain vehicle having an engine and a saddle type driver&#39;s seat. The saddle ride type all-terrain vehicle, includes, a first sensor for detecting an inclination in the left-right direction of the vehicle, and a second sensor for detecting an inclination in the front rear direction of the vehicle. Further, a controller receives outputs from said first and second sensors and determines a tumble condition based on the outputs and then outputs a tumble condition signal. Additionally, a fuel shut-off element shuts off the supply of fuel to the engine when the tumble condition signal is received from the controller. 
   In addition, the present invention is secondly characterized in that the saddle ride type all-terrain vehicle, the first and second sensor each include a movable portion displaceable in response to inclination of the vehicle. 
   Further, the present invention is thirdly characterized in that in the saddle ride type all-terrain vehicle, the first and second sensors are oriented such that extension lines, corresponding to directions of movement of said movable portions, intersected orthogonally. 
   Further, the present invention is fourthly characterized in that in the saddle ride type all-terrain vehicle, the first and second sensors are oriented such that an extension line, corresponding to a direction of movement of said movable portion one of the first and second sensors, crosses the other of the first and second sensors. 
   Further, the present invention is fifthly characterized in the saddle ride type all-terrain vehicle, which also includes, a steering shaft for supporting a steering handlebar of the vehicle, and a fuel tank disposed rearward of said steering shaft, wherein the first and second sensors are disposed between the steering shaft and the fuel tank. 
   Furthermore, the present invention is sixthly characterized in that in the saddle ride type all-terrain vehicle, the fuel tank has a shape provided with a recess at a front portion thereof, and wherein the first and second sensors are disposed in the recess. 
   According to the characteristics of the present invention, the ATV has sensors capable of detecting not only the inclination in the left-right direction of the vehicle body but also the inclination in the front-rear direction of the vehicle body, so that, in the ATV, which may be expected to run while being inclined in the left-right direction and in the front-rear direction, it is possible to determine a tumble (or rollover) condition based on the outputs from the first and second sensors and to stop the supply of fuel to the engine. 
   As described above, the first sensor and the second sensor are disposed roughly at the same position. Specifically, the two sensors are located at the same position in the vehicle length direction or in the vehicle width direction. Therefore, it is possible to detect the front-rear inclination and the left-right inclination at roughly the same position. 
   In addition, as also described above, the first sensor and the second sensor are disposed in the vicinity of the steering shaft, i.e., near a central portion of the vehicle body, so that the sensors are protected from the external sprinkles or splashes of dust, mud, water, or the like during when the vehicle is traveling along rugged terrain. 
   According to another characteristic, the tumble sensors disposed in the recess are protected by the fuel tank, so that the sensors are less liable to be influenced by external forces. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention will be described with reference to the accompanying drawings, wherein: 
       FIG. 1  is a left side view of an ATV according to one embodiment of the present invention; 
       FIG. 2  is a perspective view of the ATV according to one embodiment of the present invention; 
       FIG. 3  is a plan view of the ATV according to one embodiment of the present invention; 
       FIG. 4  is a front view of a part of the ATV according to one embodiment of the present invention; 
       FIG. 5A  is a plan sectional view of a tumble sensor; 
       FIG. 5B  is a front sectional view of the tumble sensor; 
       FIG. 6  is a block diagram showing one example of a fuel supply shut off system; and 
       FIG. 7  is a perspective view of part of the ATV, showing the layout of the tumble sensors. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Now, an embodiment of the present invention will be described below, referring to the drawings.  FIG. 2  is a perspective view of an ATV with tumble sensors mounted thereon according to one embodiment of the present invention,  FIG. 3  is a plan view of the same, and  FIG. 1  is a left side view of the same.  FIG. 4  is a front view showing a part of a left side portion of the ATV. In these figures, the ATV  1  includes an engine  2  located at a central portion of the vehicle body, a fuel tank  3  located on the upper side of the engine  2 , a rider&#39;s seat  4  and front and rear luggage carriers  5  and  6 , and a front guard  7  and an under guard  8  provided at the frontmost end of the vehicle. As understood from  FIG. 3 , a front portion of the fuel tank  3  is recessed toward the vehicle rear side, and a steering shaft  9  is provided extending vertically through a portion of the recess. In other words, the presence of the recess obviates the interference between the fuel tank  3  and the steering shaft  9 , and enables the fuel tank  3  to be expanded to the vehicle front side. In addition, as will be described later, a tumble sensor can be provided in the space formed by the recess, and the influences of external forces on the tumble sensor can be reduced by the fuel tank  3 . 
   A steering handlebar  10  is provided at an upper portion of the steering shaft  9 , and a link  11  is provided at a lower portion of the steering shaft  9 . The link  11  is connected to a front wheel  12  through a connection device not shown. Rear wheels  13  are provided at rear portions of the vehicle. A front fender  14  and a rear fender  15  including wheel wells are provided on the upper side of the front wheel  12  and the rear wheels  13  so as to cover the wheels  12  and  13 . Foot rests  44  and  45  for the rider seated astride the rider&#39;s seat  4  to put his feet on are provided between the front fender  14  and the rear fender  15 . 
   A fuel pump  16  is contained in the fuel tank  3 , and fuel pumped up by the fuel pump  16  is supplied to a fuel injection valve (not shown) through a fuel hose  17 . An exhaust pipe  18  led out from the engine  2  to the front side is led around a lateral side of the engine  2  to extend rearwards, and is connected to a muffler  19  disposed on the vehicle rear side. A catalyst  43  for cleaning and removing harmful components contained in the exhaust gas is provided inside of muffler  19 . An oxygen concentration sensor  42  is provided in the vicinity of a connection portion of the exhaust pipe  18  for connection with the muffler  19 , namely, on the immediate upstream side of the catalyst  43 . 
   The ATV  1  includes a control system for detecting the air-fuel ratio of an air-fuel mixture combusted in the engine  2  based on the concentration of oxygen in the exhaust gas and determining the amount of fuel injected by a fuel injection system based on the detection results (the fuel injection system and the control system are known and are therefore not shown in the figures). The oxygen concentration sensor  42  is provided for detecting the oxygen concentration in the exhaust gas and supplying the detection results to the control system. 
   The exhaust pipe  18  is exposed to the exterior at a lateral side of the engine  12 , and its portion on the rear side extends into an inside space surrounded by the rear fender  15 . Thus, the oxygen concentration sensor  42  is away from the feet of the rider seated astride the rider&#39;s seat  4 , and is protected by the fender  15 . Therefore, the oxygen concentration sensor  42  is not projecting to the upper side of the foot rest  44  to hamper the movements of the rider&#39;s feet, so that the oxygen concentration sensor  42  does not spoil the living-comfort properties (ride comfort) for the rider and can be provided with good performance of protection against external forces. 
   The ATV  1  includes main frames  20  and an under frame  21 , and the individual components of the vehicle are supported by the frames  20  and  21  and pipes or plates such as sub-frames and brackets, which are connected to the frames  20  and  21 . 
   Tumble sensors  46  and  47  are provided between the fuel tank  3  and the steering shaft  9 , by utilizing the portion of the recess of the fuel tank  3 . The tumble sensors  46  and  47  can be mounted to brackets (shown in  FIG. 7 ) connected to the main frames  20 . The sensor  46  is a left-right tumble sensor to generate an output according to the inclination of the vehicle body when the vehicle body is inclined in the left-right direction. On the other hand, the sensor  47  is a front-rear tumble sensor to generate an output according to the inclination of the vehicle body when the vehicle body is inclined in the front-rear direction. 
     FIG. 7  is a perspective view of an essential part of the vehicle body, showing the layout of the tumble sensors  46  and  47 . Next, the layout of the tumble sensors and a support structure therefor will be described referring principally to  FIGS. 4 and 7 . A bar  22  extending in the vehicle body left-right direction is joined to the main frames  20 ,  20 , and two sub-frames  23 ,  23 , extending rearward through the recess of the fuel tank  3 , are joined to the bar  22  so as to extend toward the vehicle body rear side therefrom. A sensor mounting stay  24  is bridgingly provided between the sub-frames  23 ,  23 . 
   The steering shaft  9  is disposed to pass vertically between the stay  24  and the bar  22 , between the sub-frames  23 ,  23 . Therefore, the tumble sensors  46  and  47  supported by the stay  24  are disposed in the space formed by the recess of the fuel tank  3  and on the rear side of the steering shaft  9 . 
   The stay  24  includes a mount surface  24   a  for the tumble sensor  46  and a mount surface  24   b  for the tumble sensor  47 . The mount surface  24   a  is a surface orthogonal to the running (or traveling) direction of the ATV  1 , while the mount surface  24   b  is a surface formed along the running direction. The tumble sensor  46  is fixed to the mount surface  24   a  by a bolt or the like, and the tumble sensor  47  is fixed to the mount surface  24   b  by a bolt or the like. 
     FIG. 5A  is a sectional plan view showing the layout of the tumble sensors, and  FIG. 5B  is a front sectional view of the same. The tumble sensors  46  and  47  include resin-made cases  50  and  51  in which magnet rollers  48  and  49  are contained, respectively. Magnetic sensors  52  and  53  are provided on the outer surface of the central portion of the cases  50  and  51 . The rollers  48  and  49  are rollable in the directions of arrows X and Y in the cases  50  and  51 , respectively. The inside shapes of the cases  50  and  51  are roughly U shaped, with a central portion being lower, so that the rollers  48  and  49  rest at the centers in the cases  50  and  51  when the vehicle body is not inclined. 
   The direction Y is along the forward running direction of the ATV  1 , and the direction X is set to be orthogonal to the direction Y. In addition, the extension line of the center line CL 1  of the roller  48  crosses at least the case  51  of the tumble sensor  47 . Specifically, the tumble sensor  46  and the tumble sensor  47  are disposed roughly at the same position in the vehicle body front-rear direction. 
   This layout of the sensors can be modified. For example, the extension line of the center line CL 2  of the roller  49  crosses at least the case  50  of the tumble sensor  46 . In this case, the tumble sensor  46  and the tumble sensor  47  are disposed roughly at the same position in the vehicle body width direction. 
   The magnetic sensors  52  and  53  generate outputs according to the magnitudes of magnetic fields sensed in response to the displacements of the rollers  48  and  49 . In this example, as the inclination of the vehicle body increases, the roller moves farther away from the magnetic sensor, so that the output level of the magnetic sensor decreases. 
   As such a type of sensor, there can be used, for example, the one described in Japanese Patent Laid-open No. Sho 60-255589. However, the tumble sensor is not limited to this type, and any of known type of inclination sensor can be used. 
     FIG. 6  is a block diagram showing one example of a fuel supply stopping system using tumble sensors. In  FIG. 6 , output signals from the tumble sensors  46  and  47  (here, outputs from the magnetic sensors  52  and  53 ) are compared with tumble reference levels in level determination units  54  and  55 . The results of determination of the levels in the level determination units  54  and  55  are used for tumble determination in a tumble determination unit (or controller)  56 . Algorithms for the tumble determination can be set in various ways, for example, the occurrence of a tumble may be determined when the level of the signal from one of the sensors shows a tumble with reference to the tumble reference level, or the tumble determination may be made on the basis of the detection levels at both the sensors in combination. The level determination units  54  and  55  and the tumble determination unit  56  can be composed of a microcomputer. 
   Incidentally, the tumble determination may be not dependent on only the detection signals from the tumble sensors  46  and  47 ; for example, the tumble determination may be conducted by taking into account throttle opening, speed, acceleration, brake signal, steering handlebar steering angle, or the like. 
   When it is determined in the tumble determination unit  56  that a tumble condition has occurred and a tumble condition signal is sent to cut off relay  57 , then, fuel cutoff relay  57  is turned ON, to close a cutoff valve  58 . The cutoff valve  58  may be provided, for example, at an intermediate portion of the fuel hose  17 . This ensures that upon a tumble of the vehicle body, the cutoff valve  58  is closed, whereby the fuel supply from the fuel pump  16  to a fuel injection valve  59  is stopped. Incidentally, the fuel supply may be stopped by closing a fuel supply pipe (fuel hose  17 ) in this manner, or, alternatively, by cutting off the power supply to the fuel pump  16 . 
   While the above embodiment has been described based on an example in which the fuel pump  16  is contained in the fuel tank  3 , the layout of the fuel pump is not limited to this example; the fuel pump may be separately provided exterior to the fuel tank. 
   In this detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part hereof, and within which are shown by way of illustration specific embodiments by which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention.