Abstract:
Provided is a configuration which prevents an engine from being unable to start in the state in which dew condensation occurred in a fuel injection pump and froze. The present invention relates to a fuel injection pump which is provided with a pump body and a hydraulic head and driven by an engine, and is characterized in that while the engine is in operation, the temperature of the hydraulic head is increased to a dew-point temperature or higher. Consequently, it is possible to increase the temperature of the hydraulic head and remove water in the fuel injection pump while the engine is in operation. Accordingly, the engine can be prevented from being unable to start in the state that dew condensation occurred in the fuel injection pump and froze.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a fuel injection pump. 
       BACKGROUND ART 
       [0002]    JP H08-128335 A discloses a fuel injection pump including a hydraulic head with a rack chamber in which a control rack is located. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         PTL 1: JP H08-128335 A 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    In the housing of the fuel injection pump, dew condensation may occur due to moisture or a vapor contained in a blow-by gas. For instance, if the engine is stopped in a condition that temperature of the rack chamber is between 0° C. and a dew point, the dew condensation occurs in the rack chamber. If outside temperature becomes lower than a freezing point, the droplets caused by the dew condensation are frozen, whereby the control rack cannot be actuated. 
         [0005]    The present invention aims to provide a technique of preventing dew condensation in the fuel injection pump and preventing the engine from being unable to start in the state that the dew condensation are frozen. 
       Technical Solutions 
       [0006]    The present invention relates to a fuel injection pump including a pump body and a hydraulic head, which is actuated by an engine, and in which during the engine is operated, a temperature of the hydraulic head is increased to not less than a dew point. 
         [0007]    Due to the structure, after starting the engine, the hydraulic head is rose in temperature and the water in the fuel injection pump is vaporized, whereby the water would not be remained in the hydraulic head. Accordingly, the dew condensation in the fuel injection pump can be prevented, and the internal members would not be frozen, thereby securing the startability of the engine. 
         [0008]    In a first embodiment of the fuel injection pump, a water passage of a cooling water for the engine is branched off such that the cooling water contacts a member disposed at an outer face of the hydraulic head, and the member is rose in temperature using the cooling water the temperature of which is increased as an engine operation to heat the hydraulic head. 
         [0009]    Preferably, in the first embodiment, the water passage is provided with a switch valve for bypassing the passage branched off toward the member disposed in the hydraulic head, and if the temperature of the hydraulic head is increased to not less than a predetermined temperature, the switch valve is operated to shut the flow of the cooling water into the member disposed in the hydraulic head. 
         [0010]    In a second embodiment of the fuel injection pump, in the hydraulic head, a water channel for circulating the cooling water is formed, and the temperature of the hydraulic head is increased by using the cooling water the temperature of which is increased as the engine operation. 
         [0011]    Preferably, in the second embodiment, the water passage is provided with a switch valve for bypassing the water channel, and if the temperature of the hydraulic head is increased to not less than a predetermined temperature, the switch valve is operated to shut the flow of the cooling water into the water channel. 
         [0012]    In a third embodiment of the fuel injection pump, an oil passage of a lubricant oil fed to the fuel injection pump is branched off such that the lubricant oil contacts a member disposed at an outer face of the hydraulic head, and the member is rose in temperature using the lubricant oil the temperature of which is increased as an engine operation to heat the hydraulic head. 
         [0013]    In a forth embodiment of the fuel injection pump, in the hydraulic head, an oil passage for circulating a lubricant oil fed to the fuel injection pump is formed, and the temperature of the hydraulic head is increased by using the lubricant oil the temperature of which is increased as an engine operation. 
         [0014]    In the third embodiment or forth embodiment, the oil passage is provided with a switch valve for bypassing the oil passage, and if the temperature of the hydraulic head is increased to not less than a predetermined temperature, the switch valve is operated to shut the flow of the lubricant oil into the oil passage. 
         [0015]    In a fifth embodiment of the fuel injection pump, the hydraulic head is attached with a heater for heating the hydraulic head. 
         [0016]    In the fifth embodiment, if the temperature of the hydraulic head is increased to not less than a predetermined temperature, the heater is stopped. 
       Advantageous Effects of Invention 
       [0017]    According to the present invention, while the engine is in operation, the temperature of the hydraulic head is raised enough to remove moisture in the fuel injection pump. Consequently, the dew condensation in the fuel injection can be prevented and the engine can be prevented from being unable to start due to freezing of the droplets caused by the dew condensation. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0018]      FIG. 1  depicts a fuel injection pump. 
           [0019]      FIG. 2  illustrates a first embodiment of the fuel injection pump. 
           [0020]      FIG. 3  is an exploded perspective view of a channel member. 
           [0021]      FIG. 4  is a graph showing temperature rises in members of an engine, while the operation of the engine. 
           [0022]      FIG. 5  illustrates a switching structure of cooling water flown to the channel member. 
           [0023]      FIG. 6  illustrates a second embodiment of the fuel injection pump. 
           [0024]      FIG. 7  illustrates a switching structure of cooling water flown to a water channel. 
           [0025]      FIG. 8  illustrates a third embodiment of the fuel injection pump. 
           [0026]      FIG. 9  illustrates a switching structure of lubricant oil flown to the channel member. 
           [0027]      FIG. 10  illustrates a forth embodiment of the fuel injection pump. 
           [0028]      FIG. 11  illustrates a switching structure of lubricant oil flown to an oil passage. 
           [0029]      FIG. 12  illustrates a fifth embodiment of the fuel injection pump. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0030]      FIG. 1  depicts a fuel injection pump  1  which includes a pump body  2  provided with a hydraulic head  3 . To the side face of the fuel injection pump  1 , a governor  4  for controlling an amount of fuel injection is attached. 
         [0031]    In the pump body  2 , a cam to which a driving force is transmitted from an engine and a tappet for transmitting the rotation of the cam are installed. In the hydraulic head  3 , a plunger which telescopically moves linked with the tappet and a control rack rotating the plunger to change the amount of fuel injection are installed. 
       First Embodiment 
       [0032]    As shown in  FIG. 2 , to the side face of the hydraulic head  3 , a plug  10  is attached. The plug  10  is a shutting member for a through hole which is formed to assemble a fuel filter and the like inside of the hydraulic head  3 , and the plug is located in the vicinity of a rack chamber in which the control rack is disposed. 
         [0033]    As shown in  FIG. 2 , at one end of the plug  10 , a male thread is formed to fix the plug to the through hole of the side of the hydraulic head  3 , and at the other end of the plug, a male thread  10   a  is formed projecting outside of the hydraulic head  3 . 
         [0034]    The plug  10  is attached with a channel member  11 . The channel member  11  includes a female thread corresponding to the male thread  10   a  of the plug  10 , and the female thread of the channel member  11  is threaded to the male thread of the plug  10 , thereby fixing the channel member to the plug. 
         [0035]    As shown in  FIGS. 2 and 3 , the channel member  11  includes a fixing portion  12  and a channel portion  13 . The channel member  11  is fixed to the hydraulic head  3  by threading the fixing portion  12  to the plug  10  in a state that the channel portion  13  and O-ring  14  are sandwiched with respect to the plug  10 . 
         [0036]    The fixing portion  12  includes a thread portion having a tube shape opening one end, and is, in the opening end, formed with a female thread  12   a  corresponding to the male thread  10   a  of the plug  10 . The side of the tube shape of the fixing portion is formed with multiple through holes, whereby inside and outside of the fixing portion are communicated with each other. 
         [0037]    The channel portion  13  covers the fixing portion  12 , and thus faces the plug  10 , thereby forming sealed internal space. At the outer periphery of the channel portion  13 , an inlet  15  and an outlet  16  are formed. Through the inlet  15  and outlet  16 , fluid such as water or oil can flow into the inside space of the channel member  11 . 
         [0038]    The O-rings  14  and  17  are located between the fixing portion  12  and the channel portion  13  and between the channel portion  13  and the plug  10 , respectively, and thus the channel member  11  is sealed. 
         [0039]    The water passage of the cooling water for the engine is branched off to the channel member  11 . To the inlet  15  and outlet  16 , a branch passage  18  is connected, and the cooling water passed through a cylinder head and the like which are members of the engine flows into the channel member  11  via the branch passage  18 . The heat of the cooling water introduced in the internal space of the channel member  11  is transferred to the hydraulic head  3  via the plug  10 . 
         [0040]      FIG. 4  depicts temperature rises while the operation of the engine. The solid line represents the temperature rise of the hydraulic head  3  where the cooling water is flown into the channel member  11 , and the chain line represents the temperature rise of the hydraulic head (conventional structure) where the cooling water is not flown into the channel member  11 . The broken line represents the temperature rise of the cooling water. 
         [0041]    As shown in  FIG. 4 , as the engine is operated, the temperature of the cooling water is rose faster than the hydraulic head  3 . The heat of the cooling water is transferred to the hydraulic head  3  through the channel member  11  and the plug  10 , and therefore, the temperature of the hydraulic head  3  is increased indirectly. 
         [0042]    Due to the above-described structure, if the engine is started in a situation that the outside temperature is low (e.g., around −20° C.) such as in cold district, the temperature of the hydraulic head  3  is increased by the same speed as the cooling water for the engine. Consequently, the hydraulic head can be rose in temperature above the dew point in a short time after the engine operation is started. 
         [0043]    Thus, the temperature of the hydraulic head  3  is increased to not less than the dew point while the engine is in operation, and the engine can be stopped where the water is not remained, which can avoid the situation that the remained water will be frozen. Therefore, the engine can be prevented from being unable to start due to the freezing. 
         [0044]    By means of the plug  10  as one member attached to the outside of the hydraulic head  3 , the temperature of the hydraulic head  3  is indirectly increased, so that the present embodiment can be easily installed in the conventional structures. 
         [0045]    Moreover, the hydraulic head  3  is heated via the plug  10  located near the control rack, so that the temperature around the control rack can be increased preferentially. Accordingly, the control rack can be prevented from freezing, thereby avoiding engine problems in fuel injection system. 
         [0046]    In the hydraulic head  3 , the heat can be transferred from the inside of the plug  10 , so that the hydraulic head  3  can be heated effectively. 
         [0047]    As illustrated in  FIG. 5 , at a junction of the cooling water passage branched off toward the channel member  11 , a switch valve  20  is disposed to switch the passage. The switch valve  20  is an electromagnetic valve configured to shut the flow toward the channel member  11  and bypass the channel member  11 . The hydraulic head  3  is provided with a temperature sensor  21  for detecting the temperature of the hydraulic head  3 . The temperature sensor  21  measures the surface temperature of the hydraulic head  3  and transmits the control signal to the switch valve  20  in accordance with the measured temperature, thereby controlling that operation. 
         [0048]    More specifically, if the measured temperature detected by the temperature sensor  21  is not less than a predetermined temperature above the dew point, the switch valve  20  is operated, and the branch passage for the channel member  11  is bypassed and the flow of the cooling water toward the channel member  11  is shut. Thus, the overheating by the cooling water can be prevented, and the temperature of the hydraulic head  3  can be prevented from being excessively increased. 
       Second Embodiment 
       [0049]    As illustrated in  FIG. 6 , the hydraulic head  3  is formed with a water channel  30 . The water channel  30  is disposed so as to round the hydraulic head  3  viewed from top. In other words, the water channel  30  is formed in all areas of the hydraulic head  3  viewed from top. 
         [0050]    The water channel  30  is connected to the branch passage branched off from the cooling water passage for the engine via a junction, and the cooling water can be flown through the water channel  30 . The heat of the cooling water introduced into the water channel  30  is transferred to the hydraulic head  3 . 
         [0051]    Due to the above-described structure, if the engine is started in a situation that the outside temperature is low (e.g., around −20° C.) such as in cold district, the temperature of the hydraulic head  3  is increased with the same speed as the cooling water for the engine. Consequently, the temperature of the hydraulic head can be increased to not less than the dew point in a short time after the engine operation is started. 
         [0052]    Thus, the temperature of the hydraulic head  3  is increased to not less than the dew point while the engine is in operation, and the engine can be stopped where the water is not remained, which can avoid the situation that the remained water will be frozen. Therefore, the engine can be prevented from being unable to start due to the freezing. 
         [0053]    As illustrated in  FIG. 7 , at the junction of the cooling water passage branched off toward the water channel  30 , a switch valve  31  is disposed to switch the passage. The switch valve  31  is an electromagnetic valve configured to shut the flow toward the water channel  30  and bypass the water channel  30 . The hydraulic head  3  is provided with a temperature sensor  32  for detecting the temperature of the hydraulic head  3 . The temperature sensor  32  measures the surface temperature of the hydraulic head  3  and transmits the control signal to the switch valve  31  in accordance with the measured temperature, thereby controlling that operation. 
         [0054]    More specifically, if the measured temperature detected by the temperature sensor  32  is not less than a predetermined temperature above the dew point, the switch valve  31  is operated, and the branch passage for the water channel  30  is bypassed and the flow of the cooling water toward the water channel  30  is shut. Thus, the overheating by the cooling water can be prevented, and the temperature of the hydraulic head  3  can be prevented from being excessively increased. 
         [0055]    As illustrated in  FIG. 6 , the structure according to the second embodiment using the water channel  30  which directly heats the hydraulic head  3  from inside can be employed with the structure according to the first embodiment using the channel member  11  which indirectly heats the hydraulic head  3 . In such structure, the switch valves  20  and  31  can be communalized. 
       Third Embodiment 
       [0056]    As illustrated in  FIG. 8 , through the channel member  11 , lubricant oil is fed, and the hydraulic head  3  is heated by the temperature of the lubricant oil is increased as the engine is operated. 
         [0057]    In this embodiment, from the oil inlet  5  for the fuel injection pump  1 , the oil passage is branched off toward the inlet  12  of the channel member  11 , and the outlet  13  of the channel member  11  is connected to the oil inlet  6  of the governor  4 . 
         [0058]    As the engine is operated, the temperature of the lubricant oil fed to the fuel injection pump  1  is rose faster than the hydraulic head  3 . The heat of the lubricant oil is transferred to the hydraulic head  3  through the channel member  11  and the plug  10 , and therefore, the temperature of the hydraulic head  3  is increased indirectly. 
         [0059]    Due to the above-described structure, if the engine is started in a situation that the outside temperature is low (e.g., around −20° C.) such as in cold district, the temperature of the hydraulic head  3  is increased by the same speed as the lubricant oil for the engine. Consequently, the hydraulic head can be rose in temperature above the dew point in a short time after the engine is started to be operated. 
         [0060]    Thus, the temperature of the hydraulic head  3  is increased not less than the dew point during operating the engine, and the engine can be stopped in the condition that the water is not remained, which can avoid the situation that the remained water will be frozen. Therefore, the engine can be prevented from being unable to start due to the freezing. 
         [0061]    As illustrated in  FIG. 9 , at a junction of the lubricant oil passage branched off toward the oil inlet  5 , a switch valve  40  is disposed to switch the passage. The switch valve  40  is an electromagnetic valve configured to shut the flow of the lubricant oil toward the channel member  11  and bypass the channel member  11 . The hydraulic head  3  is provided with a temperature sensor  41  for detecting the temperature of the hydraulic head  3 . The temperature sensor  41  measures the surface temperature of the hydraulic head  3  and transmits the control signal to the switch valve  40  in accordance with the measured temperature, thereby controlling that operation. 
         [0062]    More specifically, if the measured temperature detected by the temperature sensor  41  is not less than a predetermined temperature above the dew point, the switch valve  40  is operated, and the branch passage for the channel member  11  is bypassed and the flow of the lubricant oil toward the channel member  11  is shut. Thus, the overheating by the lubricant oil can be prevented, and the temperature of the hydraulic head  3  can be prevented from being excessively increased. 
       Forth Embodiment 
       [0063]    As shown in  FIG. 10 , the hydraulic head  3  is provided with an oil passage  50 . The oil passage  50  is an additional oil passage with respect to the lubricant oil passages which are installed in the hydraulic head  3 . The oil passage is branched off from the lubricant oil passage connected to the oil inlet  5  for the fuel injection pump  1 . 
         [0064]    The oil passage  50  is formed so as to pass the vicinity of the rack chamber containing the control rack. Thus, the rack chamber can be heated effectively, and the dew condensation of the control rack can be prevented. 
         [0065]    With operating the engine, the temperature of the lubricant oil fed to the fuel injection pump  1  is increased drastically. Such high-temperature lubricant oil passes through the oil passage  50 , and the heat of the lubricant oil is transferred to the hydraulic head  3 , whereby the hydraulic head  3  is directly heated from inside thereof. 
         [0066]    Due to the above-described structure, if the engine is started in a situation that the outside temperature is low (e.g., around −20° C.) such as in cold district, the temperature of the hydraulic head  3  is increased by the same speed as the lubricant oil for the engine. Consequently, the hydraulic head can be rose in temperature above the dew point in a short time after the engine operation is started. 
         [0067]    Thus, the temperature of the hydraulic head  3  is increased not less than the dew point while the engine is in operation, and the engine can be stopped where the water is not remained, which can avoid the situation that the remained water will be frozen. Therefore, the engine can be prevented from being unable to start due to the freezing. 
         [0068]    As illustrated in  FIG. 11 , at a junction of the lubricant oil passage branched off toward the oil passage  50  in the hydraulic head  3 , a switch valve  51  is disposed to switch the passage. The switch valve  51  is an electromagnetic valve configured to shut the flow of the lubricant oil toward the oil passage  50  and bypass the oil passage  50 . The hydraulic head  3  is provided with a temperature sensor  52  for detecting the temperature of the hydraulic head  3 . The temperature sensor  52  measures the surface temperature of the hydraulic head  3  and transmits the control signal to the switch valve  51  in accordance with the measured temperature, thereby controlling that operation. 
         [0069]    More specifically, if the measured temperature detected by the temperature sensor  52  is not less than a predetermined temperature above the dew point, the switch valve  51  is operated, and the branch passage for the oil passage  50  is bypassed and the flow of the lubricant oil toward the oil passage  50  is shut. Thus, the overheating the hydraulic head by the lubricant oil can be prevented, and the temperature of the hydraulic head  3  can be prevented from being excessively increased. 
       Fifth Embodiment 
       [0070]    As illustrated in  FIG. 12 , the hydraulic head  3  is attached with a heater  60 . The heater  60  directly heats the hydraulic head  3 . The heater  60  works after the engine starts, and heats the hydraulic head  3  while the engine is in operation. 
         [0071]    Thus, the hydraulic head  3  is heated to temperature not less than the dew point while the engine is in operation by the heater, and the engine can be stopped where the water is not remained, which can avoid the situation that the remained water will be frozen. Therefore, the engine can be prevented from being unable to start due to the freezing. 
         [0072]    The hydraulic head  3  is attached with a temperature sensor  61  for detecting the surface temperature thereof. The temperature sensor  61  measures the surface temperature of the hydraulic head  3  and transmits the control signal to the heater  60  in response to the measured temperature, thereby controlling the operation of the heater. 
         [0073]    More specifically, if the measured temperature detected by the temperature sensor  61  is not less than a predetermined temperature above the dew point, the heater  60  is stopped, and the heating of the hydraulic head  3  is stopped. Thus, the overheating by the heater  60  can be prevented, and the temperature of the hydraulic head  3  can be prevented from being excessively increased. 
         [0074]    As described above, the heater  60  is operated after the engine operation is started, so that the battery capacity for the heater  60  can be decreased. 
         [0075]    In the hydraulic head  3 , the heater  60  is located in the vicinity of the rack chamber containing the control rack. Therefore, the rack chamber can be heated effectively, and the dew condensation of the control rack can be prevented. 
       DESCRIPTION OF NUMERALS 
       [0076]      1 : fuel injection pump,  2 : pump body,  3 : hydraulic head,  4 : governor,  10 : plug,  11 : channel member,  12 : fixing portion,  13 : channel portion,  14 : O-ring,  15 : inlet,  16 : outlet,  17 : O-ring,  18 : branch passage,  20 : switch valve,  21 : temperature sensor