Patent Publication Number: US-6990940-B2

Title: Engine starting device and saddle-type traveling vehicle

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an engine starting device provided with a hot starting mechanism and a saddle-type traveling vehicle provided with the engine starting device. 
   2. Description of Related Art 
   A conventional engine starting device includes an intake pipe for introducing an air-fuel mixture to an engine, an auxiliary-air introducing channel for introducing auxiliary-air to the intake pipe, and an auxiliary-air control valve for varying the amount of auxiliary-air introduced to the intake pipe. The engine starting device is adapted to control the air-fuel ratio of the air-fuel mixture introduced into the engine by varying the amount of auxiliary-air introduced. Accordingly, the air-fuel ratio at the time of a hot start in a fuel injection internal combustion engine is controlled. 
   The conventional engine starting device is adapted in such a manner that the auxiliary-air introducing channel is closed when the engine stops and the auxiliary-air introducing channel is opened when the engine rotates. Hence, there arises a problem that the engine in a warmed state cannot be restarted quickly since the auxiliary-air introducing channel is in a closed state when the engine is stopped during travel. 
   When the starting device does not have a battery, electric power cannot be supplied to a control circuit for controlling the auxiliary-air control valve until a stable rotation of the engine at a predetermined rotary speed is achieved. For example, in the case of a motorcycle for off-road racing, the motorcycle does not have a battery, but is provided with a kick-start mechanism. Therefore, the auxiliary-air introducing channel cannot be opened when restarting the engine, and hence a problem arises in that the engine cannot be restarted even when the engine is warm. 
   In the motorcycle having the starting device of this type, the auxiliary-air introducing channel which can be opened and closed manually is provided, and hence the opening and closing operation of the auxiliary-air introducing channel has to be done manually when the engine has stopped. Therefore, when the engine stops during racing, it is difficult to quickly restart the engine. In addition, since the opening and closing operation of the auxiliary-air introducing channel has to be done manually, a problem occurs that the operator forgets to close the auxiliary-air introducing channel after restarting and hence the air-fuel mixture of a low concentration is supplied to the engine after restarting as well, which impairs sufficient demonstration of the engine performance. 
   Accordingly, it is an advantage of the present invention to provide an engine starting device and a motorcycle in which an engine can be restarted quickly and reliably when restarting the engine which has stopped during travel, irrespective of the present or the absence of a battery. This advantage is achieved by a combination of characteristics stated in the independent claims. Dependent claims define further advantageous embodiments of the present invention. 
   SUMMARY OF THE INVENTION 
   In order to achieve the above-described advantage, a first embodiment of the present invention includes a flow channel in which air sucked by an engine flows. A throttle valve is provided in the flow channel for controlling airflow. An air channel bypassing the throttle valve and communicating the upstream side and the downstream side of the throttle valve is also provided. A first opening-closing valve is capable of opening and closing a first channel portion of the air channel and a control device is provided for controlling the first opening-closing valve, a second channel portion of the air channel, which is different from the first channel portion, and a second opening-closing valve capable of opening and closing the first channel portion and the second channel portion. The first opening-closing valve is controlled by the control device to open the first channel portion when the engine stops and closes the first channel portion after the engine has started. The second opening-closing valve is adapted to be switched between a state in which the second channel portion is opened and the first channel portion is closed and a state in which the first channel portion is opened and the second channel portion is closed. 
   Accordingly, since a cold start air channel, which is an example of the second channel portion, and a hot start air channel, which is an example of the first channel portion, can be switched for use when the engine stops, the engine can be started reliably depending on the state of the engine, either the cold state or the warmed state. The control device controls the opening-closing means to open the channel constantly when the engine is stopped. 
   Preferably, the control device is adapted to control the first opening-closing valve constantly to open the first channel when the engine is stopped. The control unit preferably includes an urging unit that urges the first opening-closing valve in the direction to open the first channel portion and an actuator for closing the first channel portion against an urging force of the urging unit by driving the first opening-closing valve in the closing direction when electric power is supplied. The actuator includes a hydraulic type, an electric type, and a negative pressure responsive type, and may be other types. 
   For example, the control device includes a solenoid, a valve for closing the hot start air channel in the case where electric power is supplied to the solenoid, and a resilient device for pressing the valve so as to open the hot start air channel when no electric power is supplied to the solenoid. In this case, the resilient device is preferably adapted to generate an urging force in the direction to bring the hot start air channel into the opened state. 
   Accordingly, the electric power to open the hot start air channel when the engine is stopped is not necessary. For example, when the starting device is not provided with a battery, the engine can be restarted immediately after having been stopped. 
   Preferably, the starting device further includes a battery for supplying electric power to the control device, and a switch for selecting whether or not to supply electric power from the battery to the control device, and is adapted to control the first opening-closing valve by turning the switch ON to open the first channel portion. Accordingly, the hot start air channel can be opened only when starting the engine with the minimum power supply required. Power consumption can be reduced in comparison with the type in which the electric power is constantly supplied when the engine is stopped. 
   Preferably, the control device is adapted to control the first opening-closing valve to close the first channel portion when a rotary speed of the engine falls within a stable range. The control device is preferably adapted to control the first opening-closing valve to close the first channel portion when a predetermined period has elapsed after the engine has started. Accordingly, the air-fuel mixture at a suitable concentration can be supplied to the engine both when starting the engine and when traveling. 
   According to a second embodiment of the present invention, a saddle-type traveling vehicle provided with the above-described engine starting device is provided. The saddle-type traveling vehicle includes vehicles for traveling off road such as an off-road motorcycle or a four-wheel buggy. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a drawing showing an internal combustion engine  10  according to an embodiment of the present invention. 
       FIGS. 2(   a )– 2 ( c ) show the operation of a cold starting mechanism  30  and a hot starting mechanism  40 . 
       FIG. 3  is a flow chart showing an example of the operation of the internal combustion engine  10  according to the present embodiment. 
       FIG. 4  is a drawing showing an exemplary saddle-type traveling vehicle in which the engine starting device of the present invention may be embodied. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings, the present invention will be described via embodiments of the invention. However, the following embodiments are not intended to limit the invention relating the appended claims, and all the combinations of characteristics described in the embodiments are not necessarily essential for means for achieving the invention. 
     FIG. 1  is a drawing showing an internal combustion engine  10  according to an embodiment of the present invention. The internal combustion engine  10  includes an air intake mechanism  12  for taking air from the outside, a flow channel  14  in which air and an air-fuel mixture flow, an engine  16 , an exhaust channel  19  for exhausting combustion gas from the engine  16 , a float chamber  20  in which fuel  18  is stored, a needle valve  22  for adjusting the amount of fuel  18  supplied to the flow channel  14 , a throttle valve  24  for adjusting the flow of the air-fuel mixture in the flow channel  14 , a cold starting mechanism  30 , a hot starting mechanism  40 , and a control unit  50  for controlling the hot starting mechanism  40 . Engine  10  and its associated elements may be embodied in a saddle-type traveling vehicle such as saddle-type traveling vehicle  1  of  FIG. 4 . 
   In the flow channel  14 , a hot start air channel  26  as an example of a first channel portion and a cold start air channel  28  as an example of a second channel portion for adjusting the concentration of the air-fuel mixture flowing in the flow channel  14  are connected. The hot start air channel  26  is connected at one end thereof to the flow channel  14  upstream of the throttle valve  24 , and at the other end downstream of the throttle valve  24 . The flow rate and/or the concentration of the air-fuel mixture flowing in the flow channel  14  is adjusted by supplying air flown from one end into the flow channel  14  via the other end. The hot start air channel  26  is adapted to supply air to the flow channel  14  via the hot starting mechanism  40  and the cold starting mechanism  30  provided between one end and the other end. The hot start air channel  26  and the cold start air channel  28  may be disposed adjacent to each other. For example, the hot start air channel  26  and the cold start air channel  28  may share part of members constituting them. 
   Although the hot start air channel  26  as an example of the first channel portion and the cold start air channel  28  as an example of the second channel portion are provided separately in the present embodiment, they may be provided integrally as a single unit. For example, the hot start air channel  26  and the cold start air channel  28  may be formed by providing a partition in a single air channel and dividing the area of the air channel. In other words, a configuration in which a partition is provided at a boundary between the hot start air channel  26  and the cold start air channel  28  in the single air channel is also applicable. 
   The cold start air channel  28  is connected at one end to the flow channel  14  upstream of the throttle valve  24 , and at the other end downstream of the throttle valve  24 . The cold start air channel  28  is adapted to be capable of adjusting the flow rate and/or the concentration of the air-fuel mixture flowing in the flow channel  14  by supplying the air-fuel mixture obtained by mixing air flown from one end and fuel  18  supplied from a fuel supply channel  38  between one end and the other end into the flow channel  14  through the other end. 
   The cold starting mechanism  30  is adapted to be capable of opening and closing the cold start air channel  28  and the fuel supply channel  38 . In the cold starting mechanism  30 , the air-fuel mixture is generated in a space  32 , which is formed in the cold starting mechanism  30  when the cold start air channel  28  is opened, by mixing air supplied from the cold start air channel  28  and fuel  18  supplied from the fuel supply channel  38  connected to the cold starting mechanism  30 . 
   The cold starting mechanism  30  is adapted to be capable of opening and closing the hot start air channel  26 . In other words, the cold starting mechanism  30  is adapted to be capable of opening and closing the hot start air channel  26  and the cold start air channel  28 , so as to open the cold start air channel  28  when the hot start air channel  26  is closed and open the hot start air channel  26  when the cold start air channel  28  is closed. 
   More specifically, the cold starting mechanism  30  is inserted into the space  32 , and includes a second opening-closing valve  34  slidably provided in the space  32 . When the hot start air channel  26  is closed by advancing or retracting the second opening-closing valve  34  in the space  32  by a valve control unit  36 , the cold start air channel  28  is opened and the fuel supply channel  38  connected to the cold starting mechanism  30  is opened. On the other hand, when the hot start air channel  26  is opened by advancing or retracting the second opening-closing valve  34  in the space  32  by the valve control unit  36 , the cold start air channel  28  is closed and the fuel supply channel  38  is closed (See dotted line in the drawing). As described later, while the hot starting mechanism  40  has a solenoid  48 , the valve control unit  36  of the cold starting mechanism  30  is operated manually. Since the cold starting mechanism  30  is operated when prompt reaction is not required such as during warming up before a race, it does not matter if it is a manual operation. 
   The hot starting mechanism  40  is adapted to be capable of opening and closing the hot start air channel  26 . More specifically, the hot starting mechanism  40  is inserted into a space  42  defined inside the hot starting mechanism  40 , and has a first opening-closing valve  44  slidably provided in the space  42 . As an example of the control unit for controlling the first opening-closing valve  44 , a coil spring  46  and the solenoid  48  for advancing and retracting the first opening-closing valve  44  in the space  42 , and the control unit  50  for controlling the solenoid  48  are provided. 
   The coil spring  46  is provided so as to urge the first opening-closing valve  44  in the direction to open the hot start air channel  26 . The solenoid  48  is constructed in such a manner that the first opening-closing valve  44  closes the hot start air channel  26  when an electric current is supplied from the control unit  50 . In other words, when the electric current is not supplied to the solenoid  48 , the first opening-closing valve  44  moves by a resiliency of the coil spring  46 , and hence the hot start air channel  26  is opened, while when the electric current is supplied to the solenoid  48 , the first opening-closing valve  44  moves by a magnetic field generated by the solenoid  48 , and hence the hot start air channel  26  is closed (See dotted line in the drawing). 
   The control unit  50  includes a CPU  52 , a memory  54 , and an I/O unit  56 . The I/O unit  56  receives data on rotary speed of the engine detected by an engine speed detecting unit  80 , and supplies the data on rotary speed of the engine to the CPU  52 . The memory  54  stores a table in which the rotary speed and the rotating time of the engine  16  coordinated with the amount of electric current to be supplied to the solenoid  48 , and the CPU  52  references the table, and determines the amount of the electric current to be supplied to the solenoid  48  based on the data on the rotary speed of the engine and the rotating time of the engine  16 . The I/O unit  56  supplies the amount of electric current specified by the CPU  52  to the solenoid  48 . 
   The control unit  50  may control the hot starting mechanism  40  based on whether or not the electric power is supplied. For example, the control unit  50  may be adapted to control the solenoid  48  in such a manner that the hot start air channel  26  is closed when electric power is supplied from a generator  70 , which converts the power of the engine  16  to electric power. When the internal combustion engine  10  is further provided with a battery  90  for supplying the power to the control unit  50 , the control unit  50  may be adapted to control the solenoid  48  to close the hot start air channel  26  when the electric power is supplied from the battery  90  by turning a power switch  60  ON prior to the starting operation of the engine  16 . 
     FIG. 2  is a drawing showing states of the cold starting mechanism  30  and the hot starting mechanism  40  according to the different operating states of the engine  16 . Referring to  FIG. 1  and  FIG. 2 , the operation of the cold starting mechanism  30  and the hot starting mechanism  40  for adjusting the flow rate and/or the concentration of the air-fuel mixture flowing in the flow channel  14  will be described in the following respective states; before starting engine  16 , traveling after having started the engine, and being stopped after having started the engine; and in a case in which the internal combustion engine  10  is not provided with a battery  90  (See  FIG. 1 ). 
     FIG. 2(   a ) is a drawing showing a state of the cold starting mechanism  30  and the hot starting mechanism  40  before starting the engine  16 . Before starting the engine  16 , the cold start air channel  28  is closed and the hot start air channel  26  is opened. In the cold starting mechanism  30 , the second opening-closing valve  34  takes the closed position to close the cold start air channel, and the fuel supply channel  38  is closed as the cold start air channel  28  is closed. Therefore, no air-fuel mixture is supplied from the cold start air channel  28  to the flow channel  14 . 
   In the cold starting mechanism  30 , when the second opening-closing valve  34  takes the closed position, the hot start air channel  26  is opened in the cold starting mechanism  30 . On the other hand, in this example, since the internal combustion engine  10  is not provided with the battery  90  and hence the electric power is not supplied to the solenoid  48  from the control unit  50  before starting the engine  16 , the first opening-closing valve  44  takes the opened position to open the hot start air channel  26  by being pressed by the coil spring  46 . Therefore, before starting the engine  16 , the cold start air channel  28  is closed, and the hot start air channel  26  is opened. Therefore, air can be supplied to the flow channel  14  from the hot start air channel  26 . 
     FIG. 2(   b ) is a drawing showing a state in which the cold starting mechanism  30  and the hot starting mechanism  40  are at the time of starting the engine  16  in the cold state. When the engine  16  is in the cold state, the second opening-closing valve  34  is moved by the valve control unit  36  so that the second opening-closing valve  34  takes the opened position to allow the air-fuel mixture of a high concentration to be supplied to the engine  16 . Since both of the cold start air channel  28  and the fuel supply channel  38  are opened when the second opening-closing valve  34  takes the opened position, air and fuel  18  can be supplied to the cold starting mechanism  30  from the cold start air channel  28  and the fuel supply channel  38 . 
   On the other hand, when the second opening-closing valve  34  takes the opened position in the cold starting mechanism  30 , the hot start air channel  26  in the cold starting mechanism  30  is closed. Accordingly, air is not supplied from the hot start air channel  26  to the flow channel  14 . 
   Then, when the engine  16  is started in a state in which the cold start air channel  28  is opened and the hot start air channel  26  is closed as described above, air and fuel  18  are supplied from the cold start air channel  28  and the fuel supply channel  38  to the cold starting mechanism  30 , and consequently, the air-fuel mixture is supplied to the flow channel  14 . Accordingly, since air-fuel mixture of a high concentration is supplied to the engine  16 , the engine  16  in the cold state can easily be started. 
     FIG. 2(   c ) is a drawing showing the state of the cold starting mechanism  30  and the hot starting mechanism  40  during travel after the engine  16  has started. After the engine  16  has started, it is not necessary to supply air-fuel mixture of a high concentrate to the engine  16  any longer. As such, the second opening-closing valve  34  is moved to the closed state by the valve control unit  36 . Accordingly, the cold start air channel  28  is closed and the fuel supply channel  38  is also closed, and hence no air-fuel mixture is supplied from the cold start air channel  28  to the flow channel  14  during travel. 
   When the second opening-closing valve  34  takes the closed position in the cold starting mechanism  30 , the hot start air channel  26  is opened in the cold starting mechanism  30 . On the other hand, electric power is supplied from the generator  70  to the control unit  50  during travel and the rotary speed of the engine  16  detected by the engine speed detecting unit  80  is supplied to the control unit  50 . Then, based on the rotary speed, since an electric current is supplied from the control unit  50  to the solenoid  48 , the first opening-closing valve  44  takes the closed position to close the hot start air channel  26  in the hot starting mechanism  40 , and hence the hot start air channel  26  is closed. Therefore, air or the air-fuel mixture is supplied to the flow channel  14  neither from the cold start air channel  28  nor the hot start air channel  26 , and hence the air-fuel mixture of a concentration suitable for traveling, which is generated in the flow channel  14 , is supplied to the engine  16 . 
     FIG. 3  is a flow chart showing an example of the operation of the internal combustion engine  10  according to an embodiment of the present embodiment. Referring now to  FIG. 1  to  FIG. 3 , the operation of the internal combustion engine  10  will be described below. 
   First, the engine  16  in the cold state is started (S 100 ). At this time, the second opening-closing valve  34  takes the opened position for supplying the air-fuel mixture from the cold start air channel  28  to the flow channel  14  in the cold starting mechanism  30 . Since the engine  16  has not rotated before starting the engine  16 , an electric current has not been supplied to the solenoid  48 , and the first opening-closing valve  44  takes the opened position in the hot starting mechanism  40  ( FIG. 2(   b )). In this state, the engine is started by the engine starting device such as a kick starter (not shown). When the engine  16  has already warmed up after the engine  16  starts, the operation begins from step (S 114 ) for restarting the engine  16 , which will be described later. 
   When the engine  16  has not been started (No in S 102 ), the engine is started again (S 100 ). When the engine speed detecting unit  80  detects that the engine  16  is rotating at a predetermined rotary speed (YES in S 102 ), and a predetermined period has elapsed at a state in which the engine  16  is rotating at the rotary speed (YES in S 104 ), the control unit  50  determines that the rotary speed of the engine falls to a stable range. At this time, the predetermined time may be set to zero by the control unit  50  to determine the state in which the engine rotates at the predetermined rotary speed as the state in which the rotary speed of the engine falls to the stable range. 
   The control unit  50  closes the hot start air cannel  26  by supplying a predetermined electric current to the solenoid  48  when it is determined that the rotary speed of the engine falls within the stable range (S 106 ). Since the rotary speed of the engine falls within the stable range, the cold start air channel  28  is also closed (S 106   FIG. 2(   a )). Then, after the engine has been started, in the normal traveling state, the cold start air channel  28  and the hot start air channel  26  are both closed ( FIG. 2(   a )). Then, the control unit  50  holds the cold starting mechanism  30  and the hot starting mechanism  40  in the above-described state unless the engine  16  is stopped (NO in S 108 ). 
   On the other hand, when the rotary speed of the engine is detected to be zero by the engine speed detecting unit  80 , and hence it is determined that the engine  16  has stopped (YES in S 108 ), the control unit  50  opens the hot start air channel  26  (S 110   FIG. 2(   c )). When traveling again (NO in S 112 ), the engine  16  is restarted by the engine starting device such as the kick starter (not shown) (S 114 ). In this case, since the engine  16  is in the warmed state, the second opening-closing valve  34  in the cold starting mechanism  30  is brought into the closed state to close the cold start air channel  28 , and starts the engine  16  in the state in which the hot start air channel  26  is opened ( FIG. 2(   c )). 
   When the engine  16  has not been started (NO in S 116 ), the engine  16  is restarted (S 114 ). When the engine  16  has been started (YES in S 116 ), the engine speed detecting unit  80  detects that the engine  16  is rotating at a predetermined rotary speed (YES in S 116 ), and when a predetermined time period has elapsed at a state in which the engine  16  is rotated at the predetermined rotary speed (YES in S 118 ), the control unit  50  determines that the engine speed falls within the stable range. Then, when it is determined that the rotary speed of the engine falls within the stable range, the control unit  50  closes the hot start air channel  26  by supplying a predetermined electric current to the solenoid  48  (S 120 ). Then, the control unit  50  holds the cold starting mechanism  30  and the hot starting mechanism  40  in the above-described state unless the engine  16  is stopped (NO in S 108 ). 
   According to the present embodiment, since both of the cold start air channel  28  and the hot start air channel  26  are never opened, the air-fuel mixture of a high concentration can be supplied reliably from the flow channel  14  to the engine  16  when the engine  16  is in the cold state. In addition, since the operator does not need to operate both of the cold starting mechanism  30  and the hot starting mechanism  40 , erroneous opening operations of the cold start air channel  28  and the hot start air channel  26  are reduced. When the engine  16  is in the warmed state, the engine  16  can be restarted without detecting the temperature of the engine  16 . 
   According to the present embodiment, by configuring the hot start air channel  26  to be opened in a state in which the engine  16  has stopped, the engine  16  can immediately be restarted when the engine  16  has stopped. Also, by configuring the hot start air channel  26  to be opened and closed based on the rotary speed of the engine  16  or the time elapsed after having started the engine  16 , the air-fuel mixture at a suitable concentration can be supplied to the engine  16  both when starting the engine  16  and when traveling. 
   The examples or the applications described through the embodiments of the invention may be combined, modified, or improved as needed according to its usage, and the present invention is not limited to the above-described embodiment. The mode combined, modified, or improved as such is also included in the technical scope of the invention, as is clear from the claims.