JP2005171840A - Fuel injection pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent application of supply pressure of a low-pressure pump 13 to first and second pressure chambers 7, 8 in a non-suction state without increase in cost, in a fuel pump 1. <P>SOLUTION: In a metering valve 11 of a fuel injection pump 1, a passage 49 or fuel supplied from the low-pressure pump 13 is formed inside a valve element 44, and an outflow opening part 50 is formed in an peripheral wall of the fuel passage 49 to make the fuel flow out of the fuel passage 49. A body 45 houses the valve element 44 and has first and second discharge ports 42, 43 arranged in a displacement direction of the valve element 44. Current is applied to a solenoid 41 to displace the valve element 44, so that the first and second discharge ports 42, 43 are sequentially matched with the outflow opening part 50 and thereby the fuel in the fuel passage 49 is sequentially sucked into the first and second pressure chambers 7, 8. Therefore, application of the supply pressure to the first and second pressure chambers 7, 8 in the non-suction state is prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel injection pump that pumps fuel to a fuel pipe such as a common rail in order to inject and supply fuel to a cylinder of an internal combustion engine.

  2. Description of the Related Art Conventionally, in a fuel injection device that injects fuel into a cylinder of an internal combustion engine such as a diesel engine, a fuel injection pump that pumps fuel to a fuel pipe such as a common rail has been used. And the fuel pumped by this fuel injection pump is injected from the injector 4 mounted in each cylinder, for example via fuel piping.

  This fuel injection pump has, for example, a cam mechanism driven by an internal combustion engine, a plunger that is driven by this cam mechanism to pressurize fuel, and a cylinder that slidably accommodates this plunger to form a pressurizing chamber. A high-pressure pump element that adjusts the amount of fuel sucked into the pressurizing chamber, a low-pressure pump that sucks fuel from the fuel tank and supplies the fuel to the pressurizing chamber via the metering valve, and a pressurizing chamber And a check valve for preventing back flow from the metering valve to the metering valve. Then, the expansion and contraction of the pressurizing chamber are alternately repeated by the driving of the plunger, and the suction and pumping of fuel are repeated by the expansion and contraction of the pressurizing chamber.

  In this fuel injection pump, usually, two or more high-pressure pump elements are provided, and the fuel discharged from one metering valve is sequentially sucked into the pressurizing chamber of each high-pressure pump element. For this reason, one discharge port provided in one metering valve and a suction port provided in each pressurizing chamber are connected by a fuel passage branched into two or more. In addition, two or more check valves are arranged separately in each branched fuel passage to prevent backflow from each pressurizing chamber to the metering valve.

  However, according to this structure, all the check valves are opened while the fuel is sucked into one pressurizing chamber, so that the fuel supply pressure by the low pressure pump is also applied to the other pressurizing chambers. For this reason, the fuel cannot be sucked accurately for each pressurizing chamber, which causes a variation in the injection pressure and hence the injection amount. Moreover, useless pressure load will be applied to the check valve and the plunger constituting the pressurizing chamber.

  Therefore, a structure in which a metering valve is arranged for each high-pressure pump element is employed (for example, see Patent Document 1). In this structure, the suction port of each pressurizing chamber and the discharge port of each metering valve are connected by separate fuel passages. Therefore, by opening and closing the discharge port of the metering valve, it is possible to prevent supply pressure from the low pressure pump from being applied to the other pressurizing chambers while the fuel is being sucked into one pressurizing chamber. For this reason, problems such as variations in the injection amount and unnecessary pressure load on the check valve can be solved.

  For example, as shown in FIG. 3, such a fuel injection pump 100 includes a cam mechanism 101 driven by an internal combustion engine (not shown) and first and second pressurization chambers 102 and 103 and a cam mechanism 101. Driven by the first and second high pressure pump elements 104 and 105 for pumping fuel to the common rail, and first and second metering valves 106 for adjusting the amount of fuel sucked into the first and second pressurization chambers 102 and 103, 107, a low pressure pump 108 that sucks fuel from a fuel tank (not shown) and supplies fuel to the first and second pressurization chambers 102 and 103 via the first and second metering valves 106 and 107, and a common rail First and second pressure-feed-side check valves 109 and 110 for preventing backflow from the first and second pressure chambers 102 and 103 to the first and second pressure chambers 102 and 103 and the first and second metering valves 106. , Backflow to 107 And a first and second suction-side check valve 111 and 112 to prevent.

  The cam mechanism 101 is rotationally driven by an inner cam 115 having a pump drive shaft 113 rotated by an internal combustion engine, an elliptic cylindrical cam surface 114 formed coaxially with the pump drive shaft 113, and a cam surface 114. 1 and 2 have cam rollers 116 and 117.

  The first high-pressure pump element 104 has first short and long plungers 118 and 119 that pressurize fuel and a first cylinder (not shown) that slidably accommodates the first short and long plungers 118 and 119. The first short and long plungers 118 and 119 have one end surfaces facing each other, and a first pressurizing chamber 102 in which fuel is pressurized by the two one end surfaces and the inner peripheral wall of the first cylinder is formed. On the other end side of the first short and long plungers 118 and 119, a first shoe 120 for accommodating the first cam roller 116 so as to be freely slidable is formed.

Similarly, the second high-pressure pump element 105 has second short and long plungers 121 and 122 and a second cylinder (not shown) to form the second pressurizing chamber 103. A second shoe 123 that similarly accommodates the second cam roller 117 is formed on the other end side of the second short and long plungers 121 and 122.
Here, the first and second high-pressure pump elements 104 and 105 are 90 ° apart from each other and are disposed apart in the axial direction (the rotational axis direction of the inner cam 115).

  The first metering valve 106 is coaxially displaced by a first solenoid 124 that generates a magnetic field when energized, and a first discharge that communicates with an inlet (not shown) of the first pressurizing chamber 102. A first valve body 126 that opens and closes the outlet 125, a first spring 127 that biases the first valve body 126 in a direction opposite to a displacement direction by the first solenoid 124, a first stator 128 that constitutes a magnetic circuit, and the like. Similarly, the second metering valve 107 includes a second solenoid 129, a second valve body 131 that opens and closes a second discharge port 130 that leads to a suction port (not shown) of the second pressurizing chamber 103, a second spring 132, A second stator 133 is included.

  When the inner cam 115 rotates with the rotation of the pump drive shaft 113, for example, the first cam roller 116 is driven to rotate by the cam surface 114, and the first short and long plungers 118 and 119 are axially centered (the center of rotation of the inner cam 115). ). As a result, the first pressurizing chamber 102 is reduced, and the fuel in the first pressurizing chamber 102 is pressurized and pushed out. The extruded high-pressure fuel opens the first pressure-feed side check valve 109 as shown by X in FIG. 3 and is pumped to the common rail.

  While the first high pressure pump element 104 is pumping, the second solenoid 129 of the second metering valve 107 is energized, the second valve body 131 is displaced, and the second discharge port 130 is opened. ing. As a result, as shown by Y in FIG. 3, the fuel supplied by the low pressure pump 108 opens the second suction side check valve 112 and is sucked into the second pressurizing chamber 103. With this suction, the second pressurizing chamber 103 is expanded.

  During this time, the first solenoid 124 of the first metering valve 106 is not energized, and the first discharge port 125 is closed by the first valve body 126. Thereby, since the supply pressure by the low pressure pump 108 is interrupted by the first valve body 126, the first suction side check valve 111 is not opened.

  When the inner cam 115 further rotates from the state of FIG. 3, the pressure feeding from the first pressurizing chamber 102 is finished, the first pressure feeding side check valve 109 is closed, and the pressure feeding from the second pressurizing chamber 103 is started. The 2-pressure check valve 110 is opened. At the same time, energization to the second solenoid 129 is stopped and the second valve body 131 closes the second discharge port 130, and energization to the first solenoid 124 is started to cause the first valve body 126 to move to the first discharge port 125. Is released. As a result, the second suction side check valve 112 is closed and the suction into the second pressurization chamber 103 is finished, and the first suction side check valve 111 is opened to suck into the first pressurization chamber 102. Begins.

  As described above, in the fuel injection pump 100, while the fuel is being sucked into the first pressurizing chamber 102, the supply pressure by the low pressure pump 108 is supplied to the second pressurizing chamber 103 and the second suction side check valve 112. It does not take. Further, while the fuel is being sucked into the second pressurizing chamber 103, supply pressure by the low pressure pump 108 is not applied to the first pressurizing chamber 102 and the first suction side check valve 111. For this reason, problems such as variations in the injection amount and unnecessary pressure load applied to the first and second suction side check valves 111 and 112 can be solved.

However, a structure in which a metering valve is arranged for each high-pressure pump element as in the fuel injection pump 100 requires the same number of metering valves as the high-pressure pump element, which increases the cost.
JP 2000-282938 A

  The problem to be solved by the present invention is to prevent the supply pressure of a low pressure pump from being applied to a non-suction pressurized chamber, a check valve, etc., without increasing costs in a fuel injection pump.

[Means of Claim 1]
According to the first aspect of the present invention, the fuel injection pump includes two or more pressurizing chambers and one metering valve, and one metering valve includes one suction port and two or more metering valves. Each fuel inlet of the pressurizing chamber has two or more discharge ports connected by individual fuel flow paths. One metering valve has two or more communication patterns in which one suction port communicates with any one of two or more discharge ports, and one suction port communicates with any of two or more discharge ports. It is possible to switch three or more of the non-blocking patterns by the displacement of the valve body provided therein.

  Thus, while one suction port and one of the two or more discharge ports communicate with each other and the fuel is sucked into one of the two or more pressurization chambers, the discharge ports leading to the other pressurization chambers are Closed. For this reason, while the fuel is being sucked into one pressurizing chamber, the supply pressure of the fuel by the low pressure pump is not applied to the other pressurizing chambers. As a result, it is possible to accurately inhale fuel for each pressurizing chamber with a single metering valve without increasing costs, and to prevent unnecessary pressure loads from being applied to check valves, plungers, etc. Can do.

[Means of claim 2]
According to the second aspect of the present invention, the pressurizing chamber is formed by a plunger that pressurizes the fuel and a cylinder that slidably accommodates the plunger.

  In a metering valve of a fuel injection pump, a fuel passage for fuel supplied by a low-pressure pump is formed inside a valve body, and one opening for allowing fuel in the fuel passage to flow out is provided on a peripheral wall of the fuel passage. In the body that accommodates the valve body, two or more discharge ports are arranged in the displacement direction of the valve body. Then, by energizing the solenoid, the valve body is displaced so that one opening and two or more discharge ports are sequentially matched, whereby the fuel in the fuel passage is sequentially sucked into two or more pressurizing chambers. Let As a result, the supply pressure of the low-pressure pump is prevented from being applied to the pressurizing chamber in the non-suction state without increasing the cost.

[Configuration of Example 1]
The configuration of this embodiment will be described with reference to the drawings. The fuel injection pump 1 according to the present embodiment includes, for example, a common rail 2 that accumulates high-pressure fuel as shown in FIG. 2A, and injects fuel from the common rail 2 to each cylinder of an internal combustion engine (not shown). It is used in the accumulator fuel injection device 3.

  The fuel injection device 3 pumps fuel and has a metering valve 11 that adjusts the amount of fuel pumped, and a common rail 2 that accumulates fuel pumped from the fuel injection pump 1 in a high pressure state. The injector 4 is mounted in each cylinder of the internal combustion engine and injects the fuel pumped to the common rail 2 into each cylinder of the internal combustion engine, and the control means 5 controls the metering valve 11 according to the fuel pressure of the common rail 2. With.

  As shown in FIG. 1A, for example, the fuel injection pump 1 forms a cam mechanism 6 driven by an internal combustion engine, first and second pressurizing chambers 7 and 8, and is driven by the cam mechanism 6 to generate fuel. The first and second high pressure pump elements 9 and 10 for pumping the fuel to the common rail 2, the metering valve 11 for adjusting the amount of fuel sucked into the first and second pressurization chambers 7 and 8, and the fuel from the fuel tank 12 And a low pressure pump 13 for supplying fuel to the first and second pressurization chambers 7 and 8 via the metering valve 11 and a first for preventing a backflow from the common rail 2 to the first and second pressurization chambers 7 and 8. 2 pressure-feed side check valves 14 and 15, and first and second suction side check valves 16 and 17 that prevent backflow from the first and second pressure chambers 7 and 8 to the metering valve 11.

  The metering valve 11 and the first suction side check valve 16 are connected by a first fuel flow path 18, and the fuel passes from the metering valve 11 to the first suction side check valve 16 through the first fuel flow path 18. Flowing. The first suction side check valve 16 and the first pressurizing chamber 7 are connected by the first fuel flow passages 19 and 20, and the first pressurizing chamber 7 and the first pressure feeding side check valve 14 are the first fuel. The flow paths 20 and 21 are connected. The first fuel flow path 20 is connected to a fuel inlet (not shown) to the first pressurizing chamber 7. This suction port functions as a discharge port during pressure feeding. For this reason, in the 1st fuel flow path 20, a fuel flows in the mutually opposite direction at the time of suction | inhalation and pressure feeding. Between the metering valve 11 and the second suction side check valve 17, between the second suction side check valve 17 and the second pressure chamber 8, and between the second pressure chamber 8 and the second pressure side check valve 15 is also connected by second fuel flow paths 22, 23, 24, 25 similar to the first fuel flow paths 18, 19, 20, 21.

  The cam mechanism 6 is rotationally driven by an inner cam 28 having a pump drive shaft 26 rotated by an internal combustion engine, an elliptical cylindrical cam surface 27 formed coaxially with the pump drive shaft 26, and a cam surface 27. 1 and 2 have cam rollers 29 and 30.

  The pump drive shaft 26 has a pump timing pulley (not shown) to which rotational torque is transmitted from a crankshaft (not shown) of the internal combustion engine via a timing belt (not shown). Then, the pump drive shaft 26 and the inner cam 28 are rotationally driven by the transmitted rotational torque. The pump drive shaft 26 and the inner cam 28 rotate at a half rotation speed of the crankshaft.

  As shown in FIG. 2B, the first high-pressure pump element 9 includes a first short and long plungers 31 and 32 that pressurize the fuel, and a first cylinder that slidably accommodates the first short and long plungers 31 and 32. 33. The first short and long plungers 31 and 32 have one end surfaces facing each other, and a first pressurizing chamber 7 is formed by the two one end surfaces and the inner peripheral wall of the first cylinder 33. The first short plunger 31 has a longer axial direction than the first long plunger 32 because of the manufacturing advantage of making it easier to form the first fuel flow path 20 connected to the suction port of the first pressurizing chamber 7. The length is shortened, and the first pressurizing chamber 7 is formed at a position shifted from the center of the first cylinder 33. On the other end side of the first short and long plungers 31, 32, a first shoe 34 that accommodates the first cam roller 29 in a freely slidable manner is formed. The first shoe 34 is supported by a first shoe guide 35 so as to be slidable back and forth.

  As shown in FIG. 1A, the second high-pressure pump element 10 forms 90 ° with the first high-pressure pump element 9 and is axially connected to the first high-pressure pump element 9 (in the rotational axis direction of the pump drive shaft 26). Are located apart. Further, as shown in FIG. 2C, the second pressurizing chamber 8 is formed while the second short and long plungers 36 and 37 and the second cylinder 38 are provided in the same manner as the first high-pressure pump element 9. Similarly to the first short and long plungers 31 and 32, a second shoe 39 is formed to accommodate the second cam roller 30 so as to be slidable. The second shoe 39 is slidable back and forth by the second shoe guide 40. It is supported by.

  As shown in FIG. 1A, the metering valve 11 is displaced coaxially by a solenoid 41 that generates a magnetic field when energized, and a first discharge port 42 that communicates with the suction port of the first pressurizing chamber 7. The valve body 44 for opening and closing the second discharge port 43 leading to the suction port of the second pressurizing chamber 8, the first discharge port 42 and the second discharge port 43 are formed, and the valve body 44 is slidably accommodated. The body 45 and the valve body 44 include a spring 46 as an urging means for urging the valve body 44 in the direction opposite to the displacement direction by the solenoid 41.

  The valve body 44 includes a main body portion 47 that opens and closes the first discharge port 42 and the second discharge port 43, and a spring storage portion 48 that stores the spring 46. The valve body 44 is displaced while sliding in the body 45 in accordance with the current value energized to the solenoid 41.

  The main body 47 forms a fuel passage 49 for the fuel supplied by the low-pressure pump 13 therein. The main body 47 includes an outflow opening 50 through which the fuel in the fuel passage 49 flows out to the first and second fuel flow paths 18 and 22. The outflow opening 50 is provided through the peripheral wall of the fuel passage 49. The fuel passage 49 is formed in a cylindrical shape from one end surface (end surface on the side opposite to the solenoid 41) of the valve body 44 to the other end surface (end surface on the solenoid 41 side), and is greatly opened at one end surface. A portion opened at the one end surface forms an inflow opening 70 through which the fuel supplied from the low pressure pump 13 flows into the fuel passage 49.

  The spring accommodating portion 48 forms therein a spring chamber 51 in which the spring 46 is accommodated and one end of the spring 46 is attached. The spring chamber 51 is formed in a cylindrical shape from the other end surface of the valve body 44 toward one end surface, and is greatly opened at the other end surface. The other end of the spring 46 protruding from the other end surface is attached to the body 45.

  The body 45 slidably accommodates the valve body 44 and has a valve body sliding portion 53 that forms a fuel passage 52 for fuel supplied by the low-pressure pump 13 and a diameter larger than that of the valve body sliding portion 53. And a solenoid housing portion 54 for housing the solenoid 41.

  The valve body sliding portion 53 includes first and second discharge ports 42 and 43 arranged in the displacement direction of the valve body 44. The first and second discharge ports 42 and 43 are provided through the peripheral wall of the valve body sliding portion 53. The first discharge port 42 is connected to the first fuel flow path 18, and the second discharge port 43 is connected to the second fuel flow path 22. The valve body 44 is accommodated in the valve body sliding portion 53 so that the displacement direction of the outflow opening 50 coincides with the arrangement direction of the first and second discharge ports 42 and 43. A suction port 55 through which the fuel supplied from the low-pressure pump 13 is sucked into the fuel passage 52 is formed in one end side wall portion of the valve body sliding portion 53. Then, by increasing or decreasing the value of the current supplied to the solenoid 41, the valve body 44 is displaced while sliding in the valve body sliding portion 53, and the outflow opening 50 is connected to the first and second discharge ports 42, 43 in order.

  The solenoid housing portion 54 houses the solenoid 41 therein. On the inner peripheral side of the solenoid 41, the spring accommodating portion 48 is coaxially inserted and removed by energizing the solenoid 41. The other end of the spring 46 is attached to the other end side wall portion of the solenoid housing portion 54.

  The low-pressure pump 13 is a well-known pump driven by a pump drive shaft 26, and includes, for example, an inner rotor (not shown) having external teeth and an outer rotor (not shown) having internal teeth. A trochoid pump or the like having both inner teeth and a trochoid curve.

  The first suction side check valve 16 has a first valve body 57 that opens and closes a first suction side valve port 56 connected to the first fuel flow path 18, and a first direction in which the first suction side valve port 56 is closed. And a first spring 58 that biases the valve body 57. When the outflow opening 50 and the first discharge port 42 coincide with each other in the metering valve 11 (see FIG. 1B), the supply pressure of the low pressure pump 13 acts on the first valve body 57 and the first spring. The urging force by 58 is overcome and the first valve body 57 is pushed up from the first suction side valve port 56. As a result, the first suction side valve port 56 is opened, and the fuel in the fuel tank 12 flows from the low pressure pump 13 → the metering valve 11 → the first fuel flow path 18 → the first suction side check valve 16 → the first fuel. It flows in the order of the flow path 19 → the first fuel flow path 20 and is sucked into the first pressurizing chamber 7.

  Similarly to the first suction side check valve 16, the second suction side check valve 17 also includes a second valve body 60 that opens and closes a second suction side valve port 59 connected to the second fuel flow path 22, and 2 springs 61. When the outflow opening 50 and the second discharge port 43 coincide with each other in the metering valve 11 (see FIG. 1A), the second suction side valve port 59 is opened and the fuel in the fuel tank 12 is Flows in the order of the low pressure pump 13 → the metering valve 11 → the second fuel flow path 22 → the second suction side check valve 17 → the second fuel flow path 23 → the second fuel flow path 24 and is sucked into the second pressurizing chamber 8. Is done.

  The first pressure-feed side check valve 14 has a first ball 63 that opens and closes a first pressure-feed side valve port 62 connected to the first fuel flow path 21. When the pressure of the fuel pressurized in the first pressurizing chamber 7 becomes higher than the pressure of the fuel accumulated in the common rail 2, the fuel pressurized in the first pressurizing chamber 7 becomes the first ball 63. Is pushed up from the first pumping side valve port 62. As a result, the first pressure-feed side valve port 62 is opened, and the fuel in the first pressurizing chamber 7 flows in the order of the first fuel flow path 20 → the first fuel flow path 21 → the first pressure-feed side check valve 14, Pumped to the common rail 2.

  Similarly to the first pressure-feed-side check valve 14, the second pressure-feed-side check valve 15 also has a second ball 65 that opens and closes the second pressure-feed-side valve port 64. When the pressure of the fuel pressurized in the second pressurizing chamber 8 becomes higher than the pressure of the fuel accumulated in the common rail 2, the second pumping side valve port 64 is opened and the second pressurizing chamber 8 is opened. The fuel flows in the order of the second fuel flow path 24 → the second fuel flow path 25 → the second pressure-feed side check valve 15 and is pumped to the common rail 2.

  The control means 5 receives an electronic control device 66 (hereinafter referred to as ECU 66) that outputs a command signal (hereinafter referred to as a metering valve drive signal) for displacing the valve body 44, and a metering valve drive signal is input from the ECU 66. In addition, a pump drive circuit 67 for energizing the solenoid 41 from a battery (not shown) is included. The metering valve drive signal is a pulse-like on / off signal, and the value of the current supplied to the solenoid 41 increases or decreases as the ratio of the on time to the off time (DUTY ratio) changes.

  The ECU 66 includes a computer including a central processing unit (CPU), a storage device, an input device, an output device, and the like. The ECU 66 receives detection signals detected by a crank angle sensor 68 that detects the rotation angle of the crankshaft, a common rail pressure sensor 69 that detects the fuel pressure of the common rail 2, and other various sensors.

  In accordance with this input data, the ECU 66 performs the following processing every 90 ° crank angle. First, a pressurizing chamber for sucking fuel is selected from the first and second pressurizing chambers 7 and 8, and the amount of fuel sucked into the first and second pressurizing chambers 7 and 8 is calculated. Next, the energization period for energizing the solenoid 41 and the current value for energizing the solenoid 41 are calculated according to the selection and calculation results. Further, based on the energization period and the current value, a DUTY ratio is calculated to synthesize a metering valve drive signal. Then, this metering valve drive signal is output to the pump drive circuit 67 based on the energization period.

  The pump drive circuit 67 has a switching element (not shown) that energizes the solenoid 41 from the battery in response to the input of the metering valve drive signal. Then, the pump drive circuit 67 energizes the solenoid 41 with a current corresponding to the DUTY ratio in response to the input of the metering valve drive signal. As a result, the valve body 44 is displaced according to the current value, and the outflow opening 50 coincides with the first discharge port 42 or the second discharge port 43 so that the first pressurizing chamber 7 or the second pressurizing chamber 8 is aligned. Inhalation of fuel into the is started. When energization to the solenoid 41 stops after the calculated energization period elapses, the valve body 44 is pushed back by the spring 46, and both the first discharge port 42 and the second discharge port 43 are closed. Thereby, the suction of fuel into the first pressurizing chamber 7 or the second pressurizing chamber 8 is stopped.

[Operation of Example 1]
The effect | action of a present Example is demonstrated based on drawing. When the internal combustion engine is operated, the pump drive shaft 26 is rotationally driven to start supply of fuel by the low-pressure pump 13 and pumping of fuel by the first and second high-pressure pump elements 9 and 10. Further, the control means 5 starts selecting a pressurizing chamber for sucking fuel and adjusting the amount of fuel pumped to the common rail 2.

As a result, the fuel in the fuel tank 12 is sucked by the low pressure pump 13 and flows into the fuel passage 49 from the inflow opening 70 of the metering valve 11. Further, the fuel flows from the first discharge port 42 or the second discharge port 43 that coincides with the outflow opening 50 to the first pressurization chamber 7 of the first high-pressure pump element 9 or the second pressurization chamber of the second high-pressure pump element 10. 8 is inhaled. The fuel pressurized by the first short and long plungers 31 and 32 or the second short and long plungers 36 and 37 is pumped to the common rail 2.
Below, the effect | action of the fuel injection pump 1 is demonstrated using Fig.1 (a), (b), (c) and FIG.2 (b), (c).

  FIG. 1A shows a second communication pattern in which the outflow opening 50 and the second discharge port 43 coincide with each other and the suction port 55 communicates with the second discharge port 43. In FIG. 1A, the fuel in the fuel passage 49 pushes up the second valve body 60 to open the second suction side check valve 17 as indicated by an arrow A, and is sucked into the second pressurizing chamber 8. The Further, the fuel in the first pressurizing chamber 7 is pressurized and pushed out, and the pushed high-pressure fuel pushes up the first ball 63 as shown by an arrow B to open the first pressure-feed-side check valve 14, Pumped to the common rail 2. During this time, the first discharge port 42 is closed by the valve body 44, and the first suction side valve port 56 is closed by the first valve body 57.

  FIG. 1B shows a first communication pattern in which the outflow opening 50 and the first discharge port 42 coincide with each other and the suction port 55 communicates with the first discharge port 42. In the state of FIG. 1B, the fuel in the fuel passage 49 pushes up the first valve body 57 to open the first suction side check valve 16 and is sucked into the first pressurizing chamber 7. Further, the fuel in the second pressurizing chamber 8 is pressurized and pushed out, and the pushed high-pressure fuel pushes up the second ball 65 to open the second pressure-feeding check valve 15 and is pumped to the common rail 2. The During this time, the second discharge port 43 is closed by the valve body 44, and the second suction side valve port 59 is closed by the second valve body 60.

  In FIG. 1C, the outflow opening 50 does not coincide with any of the first and second discharge ports 42 and 43, and the suction port 55 does not communicate with any of the first and second discharge ports 42 and 43. Indicates a blocking pattern. In the state of FIG. 1C, energization to the solenoid 41 is stopped and the valve body 44 is pushed back by the spring 46. The first and second discharge ports 42 and 43 are both closed by a valve body 44. The first suction side valve port 56 is closed by a first valve body 57, and the second suction side valve port 59 is closed by a second valve body 60.

  FIG. 2B shows a state in which the first short and long plungers 31 and 32 are closest to each other in the first high-pressure pump element 9, that is, the volume of the first pressurizing chamber 7 is minimized. This is a state in which the suction into the first pressurizing chamber 7 is started as the process ends. FIG. 2C shows a state in which the second high pressure pump element 10 sucks a predetermined amount of fuel and the second short and long plungers 36 and 37 are farthest from each other, that is, the volume of the second pressurizing chamber 8. Is the maximum state, and the state where the intake of fuel has ended.

  The states shown in FIGS. 2B and 2C correspond to the states of the first and second high pressure pump elements 9 and 10 shown in FIG. In the following description, the state shown in FIGS. 2B and 2C is the state in which the rotation angle of the pump drive shaft 26 is 0 °, and the rotation direction of the pump drive shaft 26 is shown in FIG. , (C) in the counterclockwise direction.

  First, when the rotational angle of the pump drive shaft 26, that is, the inner cam 28 is 0 °, the metering valve 11 starts energization to the solenoid 41, and the valve body 44 is changed from the shut-off pattern of FIG. It is displaced so as to be the first communication pattern of b). As a result, the first discharge port 42 and the outflow opening 50 coincide with each other so that the fuel in the fuel passage 49 flows out into the first fuel flow path 18 and the first suction side check valve 16 is opened. Thereby, in the first high-pressure pump element 9, the intake of fuel into the first pressurizing chamber 7 is started. Then, as the inner cam 28 rotates, the fuel is continuously sucked, and the volume of the first pressurizing chamber 7 continues to expand.

  Thereafter, when the energization period for the solenoid 41 elapses and the energization is stopped, the valve body 44 is displaced from the first communication pattern of FIG. 1B to the blocking pattern of FIG. 1C. As a result, the outflow of fuel from the fuel passage 49 to the first fuel flow path 18 is stopped, and the first suction side check valve 16 is closed. Thereby, in the first high pressure pump element 9, the intake of fuel into the first pressurizing chamber 7 is completed. Further, since the expansion of the first pressurizing chamber 7 is also stopped by stopping the suction of fuel, the first cam roller 29 is separated from the cam surface 27. Then, with the first cam roller 29 being away from the cam surface 27, the inner cam 28 rotates until the rotation angle reaches 90 °.

  During this time, in the second high pressure pump element 10, the second cam roller 30 contacts the cam surface 27, and pressing of the second short and long plungers 36 and 37 by the cam surface 27 is started. As a result, the fuel is pushed out from the second pressurizing chamber 8 and the second pressure-feed side check valve 15 is opened to start the pressure feed to the common rail 2. As the inner cam 28 rotates, the fuel is continuously pumped, and the volume of the second pressurizing chamber 8 continues to shrink.

  Next, when the rotation angle of the inner cam 28 reaches 90 °, the second high pressure pump element 10 stops the reduction of the second pressurizing chamber 8, and the metering valve 11 energizes the solenoid 41. As a result, the valve body 44 is displaced from the shut-off pattern shown in FIG. 1C to the second communication pattern shown in FIG. As a result, the second discharge port 43 and the outflow opening 50 coincide with each other so that the fuel in the fuel passage 49 flows out into the second fuel passage 22 and the second suction side check valve 17 is opened. Thereby, in the second high-pressure pump element 10, the intake of fuel into the second pressurizing chamber 8 is started. Then, as the inner cam 28 rotates, the intake of fuel is continued, and the volume of the second pressurizing chamber 8 continues to expand.

  Thereafter, when the energization period to the solenoid 41 elapses and the energization is stopped, the valve body 44 is displaced from the second communication pattern in FIG. 1A to the interruption pattern in FIG. 1C. As a result, the outflow of fuel from the fuel passage 49 to the second fuel flow path 22 is stopped, and the second suction side check valve 17 is closed. As a result, in the second high-pressure pump element 10, the intake of fuel into the second pressurizing chamber 8 is completed. Further, since the expansion of the second pressurizing chamber 8 is also stopped by stopping the intake of fuel, the second cam roller 30 is separated from the cam surface 27. Then, with the second cam roller 30 away from the cam surface 27, the inner cam 28 rotates until the rotation angle reaches 180 °.

  During this time, in the first high-pressure pump element 9, the first cam roller 29 comes into contact with the cam surface 27, and the pressing of the first short and long plungers 31 and 32 by the cam surface 27 is started. As a result, fuel is pushed out from the first pressurizing chamber 7 and the first pressure-feed side check valve 14 is opened to start pressure feeding to the common rail 2. As the inner cam 28 rotates, the fuel is continuously pumped, and the volume of the first pressurizing chamber 7 continues to shrink.

  While the inner cam 28 rotates from 180 ° to 270 °, the metering valve 11 and the first and second high pressure pump elements 9 and 10 repeat the same operation as the inner cam 28 rotates from 0 ° to 90 °. Further, while the inner cam 28 rotates from 270 ° to 360 °, the metering valve 11 and the first and second high pressure pump elements 9 and 10 repeat the same operation as the inner cam 28 rotates from 90 ° to 180 °. It is.

[Effect of Example 1]
In the present embodiment, the fuel injection pump 1 includes a first high-pressure pump element 9 that forms the first pressurizing chamber 7, a second high-pressure pump element 10 that forms the second pressurizing chamber 8, and one metering valve. 11. The metering valve 11 has a first discharge port 42 and a second discharge port 43, and the first discharge port 42 is connected to the suction port of the first pressurizing chamber 7 by the first fuel flow path 18, and the second discharge port 43 is connected to the suction port of the second pressurizing chamber 8 by the second fuel flow path 22. Then, the first and second discharge ports 42 and 43 are sequentially opened and closed, whereby the fuel is sequentially drawn into the first and second pressurization chambers 7 and 8.

  Thereby, for example, while the first discharge port 42 is opened and the fuel is sucked into the first pressurization chamber 7, the second discharge port 43 leading to the second pressurization chamber 8 is closed. For this reason, while the fuel is sucked into the first pressurizing chamber 7, the second suction side check valve 17 is not opened, and the fuel supply pressure from the low pressure pump 13 is not applied to the second pressurizing chamber 8. As a result, the single metering valve 11 can accurately suck the fuel for each of the first and second pressurizing chambers 7 and 8, and the first short and long plungers 31 and 32, the second short and long plungers. It is possible to prevent unnecessary pressure loads from being applied to the 36, 37, the first and second suction side check valves 16, 17, and the like. Further, since it is not necessary to prepare a metering valve for each of the first and second high pressure pump elements 9, 10, the cost of the fuel injection pump 1 can be reduced.

[Modification]
In the metering valve 11 of this embodiment, the energization period of the solenoid 41 and the current value energized to the solenoid 41 are calculated, and based on these, the fuel is sucked into the first and second pressurization chambers 7 and 8. However, the present invention is not limited to this. For example, an energization stop period may be calculated instead of the energization period of the solenoid 41, and energization of the solenoid 41 may be started when the energization stop period elapses. In this case, energization is stopped at every predetermined crank rotation angle. Also, the value of the current supplied to the solenoid 41 may be calculated in consideration of the cross-sectional area of the fuel passage cross section formed by the overlapping portion of the first discharge port 42 or the second discharge port 43 and the outflow opening 50. Good. In this case, the flow rate from the fuel passage 49 toward the first and second pressurization chambers 7 and 8 can be adjusted.
In the metering valve 11 of the present embodiment, the stator constituting the magnetic circuit is not provided, but a stator may be provided as necessary.

  In the metering valve 11 of the present embodiment, when the energization to the solenoid 41 is stopped, a shut-off pattern is formed. However, the present invention is not limited to this mode. For example, the first communication pattern may be used when the energization to the solenoid 41 is stopped, and the second communication pattern and the blocking pattern may be used when the solenoid 41 is energized.

  In the metering valve 11 of the present embodiment, the valve element 44 is displaced by adjusting the current value supplied to the solenoid 41 by the DUTY control for controlling the DUTY ratio of the metering valve drive signal. However, the DUTY control is used. The valve body 44 can also be displaced without it. For example, if the solenoids 41 are arranged on both ends of the valve body 44, the first and second discharge ports 42 and 43 can be opened and closed sequentially by energizing each solenoid 41 alternately. If two solenoids 41 are arranged on one end side so that the number of turns per unit length of the coil is doubled, energization of only one solenoid 41 and energization of both solenoids 41 are alternately performed. By repeating the above, the first and second discharge ports 42 and 43 can be opened and closed sequentially.

Although the fuel injection pump 1 of the present embodiment includes two high-pressure elements (first and second high-pressure pump elements 9 and 10), it can also include three or more high-pressure pump elements. In this case, the same number of discharge ports as the high pressure pump elements may be provided in the body 45 of the metering valve 11.
Although the fuel injection device 3 of the present embodiment is a pressure accumulation type fuel injection device including the common rail 2, the present invention is also applicable to a fuel injection device in which the fuel pumped by the fuel injection pump 1 is directly injected into the cylinder. Can be applied.

(A) is an explanatory view showing a part of the fuel injection device of the present invention and showing a second communication pattern in which the suction port communicates with the second discharge port, and (b) shows the suction port. It is explanatory drawing which shows the 1st communication pattern connected with the 1st discharge port, (c) is explanatory drawing which shows the interruption | blocking pattern which the suction port does not connect with any of the 1st, 2nd discharge port. . (A) is explanatory drawing which shows the whole fuel-injection apparatus, (b) is sectional drawing which shows a 1st high pressure pump element, (c) is sectional drawing which shows a 2nd high pressure pump element. . It is explanatory drawing which shows the structure of the conventional fuel injection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection pump 7 1st pressurization chamber 8 2nd pressurization chamber 11 Metering valve 12 Fuel tank 18 1st fuel flow path 19 1st fuel flow path 20 1st fuel flow path 22 2nd fuel flow path 23 2nd Fuel channel 24 Second fuel channel 31 First short plunger 32 First long plunger 33 First cylinder 36 Second short plunger 37 Second long plunger 38 Second cylinder 42 First discharge port 43 Second discharge port 44 Valve element 55 Inlet

Claims (2)

Two or more pressurization chambers in which fuel is pressurized;
One metering which is provided in a fuel flow path connecting each fuel inlet of the two or more pressurizing chambers and a fuel tank, and adjusts the amount of fuel drawn from the fuel tank into the two or more pressurizing chambers With a valve,
The one metering valve has one suction port, and two or more discharge ports connected to respective fuel inlets of the two or more pressurizing chambers by separate fuel flow paths,
Two or more communication patterns in which the one suction port communicates with any one of the two or more discharge ports, and the one suction port does not communicate with any of the two or more discharge ports. A fuel injection pump capable of switching between three or more shut-off patterns by displacement of a valve body provided therein. The fuel injection pump according to claim 1, wherein
The pressurizing chamber is formed by a plunger that pressurizes fuel and a cylinder that slidably accommodates the plunger.

Images