JP2012026396A - Fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection pump that properly injects a proper amount of fuel to each cylinder and reduces a harmful substance to be discharged.SOLUTION: A detection shaft 43 including a plurality of slits 43a formed on its circumference surface is fixed to a plunger 41 of a fuel injection pump 3 so as to integrally reciprocate. A stroke sensor 24 is mounted on a lateral side of the detection shaft 43. When the plunger 41 and the detection shaft 43 are moved upward, the stroke sensor 24 detects the passing of the slits 43a and outputs it to an ECU 25. The ECU 25 identifies a position of the plunger 41 based on the output from the stroke sensor 24, and determines a moving distance of the plunger 41 based on the identified position. Further, the ECU 25 controls the plunger 41 to move the determined distance by controlling supply of oil pressure into an oil pressure chamber 54.

Description

  The present invention relates to a fuel injection pump, and more particularly to an electronically controlled fuel injection pump for a multi-cylinder diesel engine used as a main engine of a large vessel.

  In general, a fuel injection device for a diesel engine includes a fuel injection pump that pumps fuel to a fuel injection nozzle and injects the fuel into a combustion chamber. Further, the increase or decrease of the fuel injection amount by the fuel injection pump is performed by a governor that operates according to the operating state of the engine. A plunger that pumps fuel in the fuel injection pump is connected to the governor via a control rack. The plunger is rotated by activating the governor and displacing the control rack. When the plunger rotates, the effective stroke, which is the period during which the plunger pumps fuel, changes, and the fuel injection amount is adjusted. It is like that.

  For example, Patent Document 1 discloses a fuel injection pump that increases or decreases a fuel injection amount using a mechanical governor. The mechanical governor includes a flyweight that is opened by the action of a centrifugal force generated as the engine rotates, and a governor spring that applies a spring force in a direction in which the flyweight is closed. The control rack is displaced to a position corresponding to the position of the flyweight, that is, the balance between the centrifugal force acting on the flyweight and the spring force of the governor spring, so that the fuel injection amount of the fuel injection pump is reduced. It is increased or decreased according to the engine speed. The control rack is common to each fuel injection pump provided for each cylinder, and each plunger is rotated by a single governor and a single control rack. .

  Patent Document 2 discloses a fuel injection pump that increases or decreases the fuel injection amount using an electronically controlled governor. According to this, the actual rotational speed of the engine detected by the sensor and the target rotational speed set by the operation of the operator are compared and calculated by the controller, and the fuel injection amount is determined based on the calculation result. . An actuator for changing the position of the control rack is connected to the control rack, and the actuator displaces the control rack based on a command output from the controller so that a determined amount of fuel is injected. It has become. As in the case of Patent Document 1, the control rack rotates the plunger of the fuel injection pump provided for each cylinder, thereby increasing or decreasing the fuel injection amount.

JP 2002-155663 A JP 2008-45484 A

  Here, in order to reduce the discharge amount of harmful substances discharged from the diesel engine such as NOx (nitrogen oxide), it is necessary to accurately control the fuel injection amount in accordance with the operation state of the engine. In the case of a multi-cylinder diesel engine, there are individual differences in the amount of fuel injected from each fuel injection pump, and it is necessary to make fine adjustments to eliminate the individual differences. However, in Patent Documents 1 and 2, since the fuel injection amount in each fuel injection pump is increased or decreased by a single governor and a single control rack, the fuel injection amount cannot be finely adjusted for each cylinder. It has become. Therefore, an appropriate amount of fuel cannot be injected into each cylinder, and there is a problem in that there is a limit to measures for reducing the emission of harmful substances.

  The present invention has been made to solve such problems, and has realized that an appropriate amount of fuel is accurately injected into each cylinder, thereby reducing the emission of harmful substances. An object is to provide a fuel injection pump.

  A fuel injection pump according to the present invention includes a pump body having a boosting chamber to which fuel is supplied, a plunger that is slidably provided in the pump body, and a drive unit that reciprocally moves the plunger. In the fuel injection pump that boosts and discharges the fuel in the boosting chamber by reciprocating the plunger, the fuel injection pump has a plurality of slits arranged along the plunger moving direction, and reciprocates integrally with the plunger. A shaft, a stroke sensor that is provided on a side of the detection shaft and detects and outputs the passage of the slit; and a control unit that receives an output from the stroke sensor; and the control unit outputs an output from the stroke sensor. Based on the specified plunger position, the plunger position is determined based on the plunger position. The moving distance determined, the determined movement of the moving distance as the plunger is carried out, is characterized in that for controlling the drive unit.

  Since the plunger and the detection shaft are integrally reciprocated and the stroke sensor for detecting the slit of the detection shaft is provided, the movement of the plunger is controlled based on the number of slits passing through the stroke sensor. That is, when the fuel injection pump according to the present invention is applied to a multi-cylinder diesel engine, the amount of movement of each plunger can be individually controlled, unlike the case where a governor and a control rack are used. It becomes possible to eliminate individual differences in quantity. Therefore, in the fuel injection pump, an appropriate amount of fuel is accurately injected into each cylinder, thereby reducing the amount of harmful substances discharged.

  The control unit may use the position of the plunger when the plunger reaches the position farthest from the boost chamber as a reference point for determining the movement distance of the plunger. Since the so-called zero point can be guaranteed every time the plunger reciprocates, highly accurate fuel injection can be performed. In the pump body, a hydraulic chamber to which hydraulic oil is supplied is formed on the end portion side opposite to the pressure boosting chamber of the plunger, and the drive unit supplies the hydraulic oil to the hydraulic chamber. A first hydraulic solenoid valve and a second hydraulic solenoid valve that allows the hydraulic oil to be discharged from the hydraulic chamber may be included.

  An air chamber to which compressed air is supplied is formed in the pump body, and the plunger may be biased toward the hydraulic chamber by the compressed air in the air chamber. Further, the compressed air in the air chamber may be discharged to the outside of the pump main body through a space between the outer peripheral surface of the plunger and the inner peripheral surface of the pump main body. Due to the pressure of the compressed air discharged, it is possible to prevent the fuel in the pressure increasing chamber from leaking into the air chamber through the space between the outer peripheral surface of the plunger and the inner peripheral surface of the pump body.

  According to the present invention, in the fuel injection pump, it is possible to accurately inject an appropriate amount of fuel into each cylinder, thereby reducing the discharge amount of harmful substances.

It is the schematic which shows the fuel-injection apparatus provided with the fuel-injection pump which concerns on Embodiment 1 of this individual invention. It is a cross-sectional side view which shows the fuel-injection pump which concerns on Embodiment 1, and has shown the state at the time of a plunger raise. FIG. 3 is a cross-sectional side view showing a configuration of a plunger and a detection shaft in the fuel injection pump according to the first embodiment. FIG. 3 is a partial enlarged cross-sectional side view showing a configuration around a plunger in the fuel injection pump according to the first embodiment. It is a cross-sectional side view for demonstrating operation | movement of the fuel injection pump which concerns on Embodiment 1, and has shown the state at the time of plunger lowering.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
The configuration of the fuel injection pump according to the first embodiment will be described by taking as an example a case where it is applied to the fuel injection device 1 of a multi-cylinder diesel engine used as a large marine main engine.
As schematically shown in FIG. 1, a fuel injection device 1 includes a fuel tank 2 in which fuel is stored, a fuel injection pump 3 that boosts and discharges fuel supplied from the fuel tank 2, and a fuel injection pump 3 Is provided with a fuel injection nozzle 4 for injecting the fuel discharged into the combustion chamber (not shown). A feed pump 6 is provided in the middle of the fuel supply pipe 5 connecting the fuel tank 2 and the fuel injection pump 3 so that the fuel in the fuel tank 2 is supplied to the fuel injection pump 3 by the feed pump 6. It has become. The fuel injection pump 3 and the fuel injection nozzle 4 are connected via a high-pressure pipe 7. Although only a single fuel injection pump 3 and a single fuel injection nozzle 4 are shown in FIG. 1, these are provided in a number corresponding to each cylinder of the engine.

  The fuel injection pump 3 includes a first hydraulic solenoid valve 8 provided on one side and a second hydraulic solenoid valve 9 provided on the other side. The first hydraulic electromagnetic valve 8 is for supplying hydraulic oil supplied from the hydraulic oil tank 10 to the inside of the fuel injection pump 3, and the second hydraulic electromagnetic valve 9 is supplied from the inside of the fuel injection pump 3. This is to allow the hydraulic oil to be discharged. As will be described in detail later, the fuel injection pump 3 moves the plunger provided therein by the hydraulic pressure of the hydraulic oil, thereby boosting and discharging the fuel. That is, the first hydraulic solenoid valve 8 and the second hydraulic solenoid valve 9 constitute a drive unit in the fuel injection pump 3. The first hydraulic solenoid valve 8 and the second hydraulic solenoid valve 9 are electrically connected to an ECU 25 that is a control unit in the fuel injection pump. ECU25 specifies the position of a plunger based on the output from the stroke sensor mentioned later, and determines the movement distance of a plunger based on the position of the specified plunger. In addition, the ECU 25 controls the first hydraulic solenoid valve 8 and the second hydraulic solenoid valve 9 so that the plunger moves the determined movement distance.

  A hydraulic oil supply pipe 11 is connected to the hydraulic oil tank 10, and hydraulic oil in the hydraulic oil tank 10 is supplied to the block 13 by a hydraulic pump 12 provided in the middle thereof. The first hydraulic solenoid valve 8 is fixed to the upper surface of the block 13, and the fuel injection pump 3 is supported by the block 13 via the first hydraulic solenoid valve 8. The hydraulic oil supplied to the block 13 sequentially flows through the internal passage 13a of the block 13 and the internal passage 8a of the first hydraulic solenoid valve 8, and when the first hydraulic solenoid valve 8 is opened by a command from the ECU 25, fuel injection is performed. It is supplied into the pump 3. On the other hand, when the second hydraulic solenoid valve 9 is opened by a command from the ECU 25, the hydraulic oil in the fuel injection pump 3 can be discharged. The discharged hydraulic oil is returned to the hydraulic oil tank 10 through the internal passage 9a and the hydraulic oil discharge pipe 14 of the second hydraulic solenoid valve 9 in order.

  The first hydraulic solenoid valve 8 and the second hydraulic solenoid valve 9 each have a spool (not shown) provided therein. By switching the positions of these spools based on a command from the ECU 25, the first hydraulic solenoid valve 8 and the second hydraulic solenoid valve 9 can be opened and closed. The first hydraulic solenoid valve 8 and the internal passage 13 a of the block 13 are connected via a connection pipe 15, and the spool of the first hydraulic solenoid valve 8 is driven by hydraulic oil supplied through the connection pipe 15. It is like that. Similarly, the second hydraulic solenoid valve 9 and the internal passage 13a are connected via a connection pipe 16, and the spool of the second hydraulic solenoid valve 9 is driven by hydraulic oil supplied through the connection pipe 16. It is like that. Further, an accumulator 17 for accumulating the pressure of the hydraulic oil supplied from the hydraulic oil tank 10 and a pressure sensor 18 for detecting the hydraulic pressure in the internal passage 13a are connected midway in the internal passage 13a of the block 13.

  In addition, a regulator 19 and a tank 20 for supplying compressed air to the inside of the fuel injection pump 3 are connected via a pneumatic pipe 21. In particular, diesel engines for large ships generally have a compressed air source for operating a piston using compressed air when the engine is started, and compressed air from the compressed air source is supplied to the regulator 19. It has come to be. The compressed air is decompressed by the regulator 19 and then accumulated in the tank 20, and the compressed air in the tank 20 is supplied into the fuel injection pump 3 via the pneumatic pipe 21. Further, the compressed air in the fuel injection pump 3 is discharged through the pneumatic pipe 22. A throttle valve 23 is provided in the middle of the pneumatic pipe 22, and the air pressure in the fuel injection pump 3 is maintained within a predetermined range by adjusting the throttle valve 23 in advance.

Here, the configuration of the fuel injection pump 3 will be described in detail with reference to FIGS. In addition, the up-down direction in the fuel injection pump 3 is prescribed | regulated by the arrow shown in FIG. Further, the fuel injection pump 3 shown in FIG. 2 and subsequent figures is illustrated in a state where the first hydraulic solenoid valve 8 and the second hydraulic solenoid valve 9 shown in FIG. 1 are omitted.
As shown in FIG. 2, the fuel injection pump 3 includes a first housing 31 in which a substantially cylindrical through hole extending in the vertical direction is formed. A second housing 32 is provided above the first housing 31, and the first housing 31 and the second housing 32 are joined together by a plurality of bolts 33. On the other hand, a third housing 34 having a substantially cylindrical shape is fitted to the lower portion of the first housing 31 and is joined to the first housing 31 by a bolt (not shown). Further, a fourth housing 35 is joined to the lower part of the third housing 34 by a bolt 36, and a shaft housing 37 is joined to the lower part of the fourth housing 35 by a bolt 38.

  A plunger barrel 39 having a substantially cylindrical shape is inserted into the inner peripheral portion of the first housing 31. The plunger barrel 39 is held between a shoulder portion 31a (see FIG. 4) formed on the inner peripheral portion of the first housing 31 and an equal pressure valve 40 provided on the upper portion of the plunger barrel 39. The plunger barrel 39 and the equal pressure valve 40 are fixed in the first housing 31 by joining the housing 32 to the first housing 31 with a bolt 33. Here, the first housing 31, the second housing 32, the third housing 34, the fourth housing 35, the shaft housing 37, and the plunger barrel 39 constitute a pump body in the fuel injection pump 3.

  An annular groove is formed in the inner peripheral portion of the first housing 31, and a fuel reservoir chamber 51 is defined between the groove and the outer peripheral surface of the plunger barrel 39. A fuel supply pipe 5 is connected to the fuel reservoir 51 so that fuel from the fuel tank 2 is supplied into the fuel reservoir 51. Further, a feed hole 39a penetrating in the lateral direction is formed in the plunger barrel 39 at a portion located in the fuel reservoir chamber 51, and the fuel reservoir chamber 51 and the inner peripheral portion of the plunger barrel 39 are connected to the feed hole. It is in the state which communicated via 39a.

  A plunger 41 for performing pressure increase and discharge of fuel is slidably provided on the inner peripheral portion of the plunger barrel 39. The inner peripheral portion of the plunger barrel 39, the lower surface of the equal pressure valve 40, and the upper surface 41a of the plunger 41 are provided. A boosting chamber 52 (see FIG. 4) is formed. When the plunger 41 is lowered, a part of the feed hole 39a of the plunger barrel 39 is located above the upper surface 41a of the plunger 41, so that the fuel in the fuel reservoir 51 is fed into the feed hole. It flows into the pressure increasing chamber 52 through 39a. On the other hand, as shown in FIG. 2, when the plunger 41 rises, the feed hole 39 a is closed by the outer peripheral surface of the plunger 41. In other words, the fuel injection pump 3 boosts the fuel supplied into the booster chamber 52 when the plunger 41 is lowered by raising the plunger 41. The fuel boosted in the boosting chamber 52 flows through the isobaric valve 40 and is discharged into the high-pressure pipe 7 and is injected into the combustion chamber from the fuel injection nozzle 4 (see FIG. 1). The isobaric valve 40 keeps the pressure of the fuel remaining in the downstream side of the fuel injection pump 3, that is, the high pressure pipe 7 and the fuel injection nozzle 4 (see FIG. 1) within a predetermined range after the plunger 41 discharges the fuel. It is for holding.

  A piston 42 having a substantially cylindrical shape with a bottom is provided at the lower end of the plunger 41, and the piston 42 slides in the third housing 34. The piston 42 is disposed such that its bottom 42 e is positioned on the lower side. Inside the third housing 34, an inner peripheral portion of the piston 42, a lower surface of the first housing 31, and an inner periphery of the third housing 34 are arranged. An air chamber 53 that is partitioned into a surface is formed. On the other hand, a hydraulic chamber 54 defined by a bottom 42 e, an inner peripheral surface of the third housing 34 and an upper surface of the fourth housing 35 is formed below the piston 42.

  A detection shaft 43 that extends through the fourth housing 35 and extends into the shaft housing 37 is provided at the lower end of the piston 42, and the detection shaft 43 slides within the shaft housing 37. It is like that. A plurality of slits 43a (see FIG. 3), which are grooves formed along the circumferential direction, are arranged on the outer peripheral surface of the detection shaft 43 along the axial direction, that is, the direction in which the plunger 41 moves. Further, the stroke sensor 24 is attached to a portion of the shaft housing 37 located on the side of the detection shaft 43, and the stroke sensor 24 and the slit 43a are opposed to each other. The stroke sensor 24 detects that the slit 43 a has passed when the detection shaft 43 moves, and is electrically connected to the ECU 25. When the stroke sensor 24 detects the passage of the slits 43a, a rectangular wave corresponding to the number of the slits 43a that have passed is output to the ECU 25. The ECU 25 identifies the position of the plunger 41 by counting the number of rectangular waves from the stroke sensor 24, and determines the movement distance of the plunger 41 based on the identified position.

  As shown in FIG. 3, the plunger 41 and the piston 42 are integrally fixed by joining a spacer 44 holding the plunger 41 to the piston 42 with a bolt 45. The piston 42 and the detection shaft 43 are fixed together by joining a spacer 46 holding the detection shaft 43 to the piston 42 with a bolt 47. That is, the plunger 41, the piston 42, and the detection shaft 43 integrally move reciprocally along the axial direction (see arrow A in FIG. 2).

  Returning to FIG. 2, a connection port 34 a that connects the outside and the inside of the third housing 34 is formed on one side of the third housing 34, and the first hydraulic solenoid valve 8 is connected to the connection port 34 a. An internal passage 8a (see FIG. 1) is connected. Further, a connection port 34b is formed on the opposite side of the connection port 34a to communicate the outside and the inside of the third housing 34, and the internal passage 9a of the second hydraulic solenoid valve 9 is connected to the connection port 34b. ing.

  Here, as shown in FIG. 4 in which the plunger 41 is lowered, the piston 42 provided in the third housing 34 communicates with a communication groove 42a formed on the outer peripheral surface located on the connection port 34a side. A communication hole 42b is provided for communicating the groove 42a with the hydraulic chamber 54 (see FIG. 2). Further, the piston 42 has a communication groove 42 c formed on the outer peripheral surface located on the connection port 34 a side, and a communication hole 42 d for communicating the communication groove 42 c and the hydraulic chamber 54. When the plunger 41 is lowered, the communication groove 42a and the communication groove 42c are formed so as to be located at portions that partially overlap the connection port 34a and the connection port 34b, respectively.

  Therefore, when the plunger 41 is lowered, when the first hydraulic solenoid valve 8 is opened and the second hydraulic solenoid valve is closed, the hydraulic oil is supplied into the hydraulic chamber 54, and the piston 42 is pushed up by the hydraulic pressure. The plunger 41 and the detection shaft 43 move upward. On the contrary, in the state where the communication groove 42a and the communication groove 42c overlap with the connection port 34a and the connection port 34b, the first hydraulic solenoid valve 8 is closed and the second hydraulic solenoid valve 9 is opened. As a result, the hydraulic oil in the hydraulic chamber 54 can be discharged to the outside of the fuel injection pump 3.

  The first housing 31 has a connection port 31 b that is a hole formed on one side, and a communication hole 31 c that communicates the connection port 31 b and the air chamber 53. A pneumatic pipe 21 is connected to the connection port 31b, and compressed air in the tank 20 (see FIG. 1) is supplied into the air chamber 53 via the connection port 31b and the communication hole 31c in sequence. Yes. On the other hand, a connection port 31d is formed on the side of the first housing 31 located on the side opposite to the connection port 31b, and the pneumatic piping 22 is connected to the connection port 31d. The first housing 31 has a communication hole 31e that allows the connection port 31d and the air chamber 53 to communicate with each other, and a branch hole 31f that branches in the middle of the communication hole 31e and penetrates the inner periphery. Here, the plug 48 is inserted into the communication hole 31e from the lower side of the first housing 31, and the outlet of the communication hole 31e on the air chamber 53 side is closed.

  The plunger barrel 39 is formed with a through hole 39c penetrating from the portion facing the branch hole 31f to the inner peripheral surface 39b of the plunger barrel 39. Therefore, the compressed air supplied into the air chamber 53 through the connection port 31 b and the communication hole 31 c penetrates through a minute gap between the inner peripheral surface 39 b of the plunger barrel 39 and the outer peripheral surface 41 b of the plunger 41. It reaches the hole 39c, and then is discharged to the outside of the fuel injection pump 3 through the through hole 39c, the communication hole 31e, and the pneumatic pipe 22 sequentially. In other words, the air pressure of the compressed air discharged from the air chamber 53 is constantly acting in the minute gap between the inner peripheral surface 39b of the plunger barrel 39 and the outer peripheral surface 41b of the plunger 41. As a result, the fuel in the pressurizing chamber 52 is prevented from leaking into the air chamber 53 through the space between the inner peripheral surface 39b of the plunger barrel 39 and the outer peripheral surface 41b of the plunger 41. .

  As described above, the pneumatic pipe 22 for discharging the compressed air to the outside of the fuel injection pump 3 is provided with the throttle valve 23. By adjusting the throttle valve 23 in advance, the inside of the air chamber 53 is adjusted. The air pressure is maintained within a predetermined range. That is, the compressed air in the air chamber 53 is always in a state of biasing the piston 42 toward the hydraulic chamber 54 by its air pressure. Therefore, when the plunger 41 is raised to discharge the fuel in the boosting chamber 52 and the hydraulic pressure in the hydraulic chamber 54 is lowered, the plunger can be lowered by the compressed air in the air chamber 53. When the plunger 41 is lowered and the positions of the communication groove 42a and the communication groove 42c overlap with the connection port 34a and the connection port 34b, the first hydraulic solenoid valve 8 is closed and the second hydraulic solenoid valve 9 is turned on. When the valve is opened, the hydraulic oil in the hydraulic chamber 54 is discharged to the outside of the fuel injection pump 3, so that the plunger 41 can be pushed down to the lowest position.

Next, operation | movement of the fuel-injection apparatus 1 provided with the fuel-injection pump 3 which concerns on this Embodiment 1 is demonstrated.
As shown in FIG. 1, when the diesel engine is started, the feed pump 6 operates to supply the fuel in the fuel tank 2 to the fuel injection pump 3. The hydraulic pump 12 is also operated to supply hydraulic oil for driving a spool (not shown) to the first hydraulic electromagnetic valve 8 and the second hydraulic electromagnetic valve 9. The first hydraulic solenoid valve 8 is also supplied with hydraulic oil for supply into the fuel injection pump 3. In addition, compressed air from the tank 20 is supplied into the fuel injection pump 3.

  As shown in FIG. 2, when the plunger 41 is in the raised position, the communication between the boost chamber 52 (see FIG. 4) and the fuel reservoir chamber 51 is cut off. Thus, the fuel supplied to the fuel injection pump 3 stays in the fuel reservoir 51. Further, since the plunger 41 is raised, the hydraulic pressure in the hydraulic chamber 54 is in a lowered state. Since compressed air is supplied into the air chamber 53, the piston 42 is urged downward, so that the plunger 41, the piston 42, and the detection shaft 43 are integrally moved downward. Start moving.

  Here, when the plunger 41 is lowered, the ECU 25 (see FIG. 1) outputs a valve closing command to the first hydraulic solenoid valve 8 and outputs a valve opening command to the second hydraulic solenoid valve 9. ing. Therefore, when the plunger 41 is lowered to a position where the connection ports 34a and 34b of the third housing 34 and the communication grooves 42a and 42c of the piston 42 are respectively overlapped, the hydraulic oil remaining in the hydraulic chamber 54 is moved by the piston 42. It is pushed out from the inside of the hydraulic chamber 54 and discharged to the internal passage 9a of the second hydraulic solenoid valve 9 through the communication hole 42d, the communication groove 42c and the connection port 34b of the piston 42 sequentially. As the hydraulic oil is discharged from the hydraulic chamber 54, the plunger 41 is lowered to a position where the lower surface of the piston 42 contacts the fourth housing 35. As the plunger 41 descends, a part of the feed hole 39a of the plunger barrel 39 is positioned above the upper surface 41a of the plunger 41, so that the fuel in the fuel reservoir 51 passes through the feed hole 39a. Via the pressure chamber 52.

  As shown in FIG. 5, when the plunger 41 descends and moves to a position farthest from the pressurizing chamber 52, that is, a position where the fourth housing 35 and the piston 42 contact each other, the upward movement of the plunger 41 is started. The First, the ECU 25 sets the position of the plunger 41 when the fourth housing 35 and the piston 42 contact each other as a reference point for determining the movement distance of the plunger 41, a so-called zero point. Further, the ECU 25 outputs a valve opening command to the first hydraulic solenoid valve 8 and outputs a valve closing command to the second hydraulic solenoid valve 9. When the first hydraulic solenoid valve 8 is opened by a valve opening command from the ECU 25, the inside of the hydraulic chamber 54 sequentially passes through the internal passage 8a, the connection port 34a, the communication groove 42a, and the communication hole 42b of the first hydraulic solenoid valve 8. Is supplied with hydraulic oil. At the same time, the second hydraulic solenoid valve 9 is closed based on a valve closing command from the ECU 25, so that the discharge of the hydraulic oil from the hydraulic chamber 54 is stopped and the hydraulic chamber 54 is filled with the hydraulic oil.

  When the hydraulic pressure of the hydraulic oil filling the hydraulic chamber 54 exceeds the air pressure of the compressed air in the air chamber 53, the plunger 41 starts moving upward as indicated by an arrow B in FIG. As the movement of the plunger 41 starts, the slits 43a of the detection shaft 43 pass through the stroke sensor 24 one after another. The stroke sensor 24 detects the passage of the slits 43a and outputs a rectangular wave corresponding to the number of slits that have passed to the ECU 25. The ECU 25 identifies the position of the plunger 41 by counting the number of rectangular waves received from the stroke sensor 24, and based on the identified position of the plunger 41, moves the plunger 41 to the boosting chamber 52 side, that is, upward. Determine the travel distance. Next, the ECU 25 determines the opening time of the first hydraulic solenoid valve 8 and the closing time of the second hydraulic solenoid valve 9 based on the determined movement distance of the plunger 41. When the opening time or closing time of the first hydraulic solenoid valve 8 and the second hydraulic solenoid valve 9 is controlled by the ECU 25, the moving distance of the plunger 41 upward is controlled.

  The plunger 41 is raised by the distance determined by the ECU 25 to boost the fuel in the boosting chamber 52 and discharge the boosted fuel to the high-pressure pipe 7 through the isobaric valve 40. The fuel discharged to the high pressure pipe 7 opens the fuel injection nozzle 4 (FIG. 1) by the pressure, and is injected into a combustion chamber (not shown). After the fuel injection is completed, the fuel injection pump 3 returns to the state shown in FIG. 2, and thereafter, the plunger 41 repeats the vertical movement under the control of the ECU 25. Here, the ECU 25 sets the position of the plunger 41 when the plunger 41 reaches the lowest side to the zero point. Therefore, the zero point is guaranteed every time the plunger 41 is reciprocated, so that highly accurate fuel injection is performed. It is possible to do. Further, the compressed air from the air chamber 53 passes through a minute gap between the inner peripheral surface 39b of the plunger barrel 39 and the outer peripheral surface 41b of the plunger 41, the through hole 39c, the communication hole 31e, the connection port 31d, and the pneumatic piping 22. They are discharged sequentially. Therefore, the fuel in the pressure increasing chamber 52 is sealed by the compressed air between the plunger barrel 39 and the plunger 41, and the fuel is prevented from leaking into the air chamber 53. Yes.

  The control of the operation of the fuel injection pump 3 described above is performed individually for each fuel injection pump 3 provided for each cylinder. Therefore, in the multi-cylinder diesel engine, the fuel injection amount in each fuel injection pump 3 can be individually controlled, and individual differences in the fuel injection amount can be eliminated. That is, since an appropriate amount of fuel is accurately injected in each cylinder, it is possible to reduce the discharge amount of harmful substances. A common rail system is an example of a fuel injection device for a diesel engine. However, a diesel engine for a large vessel has a large amount of fuel to be injected at one time, so the pressure for performing the next fuel injection in the common rail system. As a result, there is a problem that it is difficult to inject an appropriate amount of fuel. That is, the fuel injection pump 3 according to the present invention solves the above-described problems of the fuel injection device using the common rail system.

  As a method of detecting the position of the plunger, for example, the plunger is conical and a distance sensor such as a laser type is arranged on the side of the plunger, and changes between the plunger side surface and the sensor. A method of detecting the distance between them is also considered as an example. However, since a marine diesel engine generally has a large lateral vibration, the method of detecting a lateral distance as described above has a problem that a detection error increases due to the influence of the vibration. On the other hand, the detection of the position of the plunger 41 in the present invention is based on detecting the passage of the slit 43a that moves in the vertical direction. Has the effect of becoming possible.

  Thus, since the plunger 41 and the detection shaft 43 are reciprocally moved as a unit and the stroke sensor 24 for detecting the slit 43a of the detection shaft 43 is provided, the number of slits 43a passing through the stroke sensor 24 is increased. Based on this, the movement of the plunger 41 is controlled. That is, when the fuel injection pump 3 is applied to a multi-cylinder diesel engine, the amount of movement of each plunger 41 can be individually controlled, unlike the case where a governor and a control rack are used. It becomes possible to eliminate individual differences. Therefore, in the fuel injection pump 3, an appropriate amount of fuel is accurately injected into each cylinder, thereby reducing the amount of harmful substances discharged.

  Further, since the ECU 25 uses the position of the plunger 41 when the plunger 41 reaches the position farthest from the boosting chamber 52 as a reference point for determining the movement distance of the plunger 41, the ECU 41 reciprocates. In other words, a so-called zero point can be guaranteed every time, and highly accurate fuel injection can be performed. Further, since the compressed air in the air chamber 53 is discharged to the outside of the fuel injection pump 3 through the space between the outer peripheral surface 41b of the plunger 41 and the inner peripheral surface 39b of the plunger barrel 39, the compressed air discharged The air pressure prevents the fuel in the pressure increasing chamber 52 from leaking into the air chamber 53 through the space between the outer peripheral surface 41 b of the plunger 41 and the inner peripheral surface 39 b of the plunger barrel 39.

  3 fuel injection pump, 8 first hydraulic solenoid valve (drive unit), 9 second hydraulic solenoid valve (drive unit), 24 stroke sensor, 25 ECU (control unit), 31 first housing (part of pump body), 32 Second housing (part of pump body), 34 Third housing (part of pump body), 35 Fourth housing (part of pump body), 37 Shaft housing (part of pump body), 39 Plunger barrel (A part of the pump main body), 39b inner peripheral surface of the plunger barrel (inner peripheral surface of the pump main body), 41 plunger, 41b outer peripheral surface of the plunger, 43 detection shaft, 43a slit, 52 pressurizing chamber, 53, air chamber, 54 Hydraulic chamber.

Claims (5)

A pump body having a boosting chamber to which fuel is supplied;
A plunger slidably provided in the pump body;
A fuel injection pump that boosts and discharges the fuel in the pressure-increasing chamber by reciprocating the plunger.
A detection shaft having a plurality of slits arranged along a movement direction of the plunger and reciprocating integrally with the plunger;
A stroke sensor that is provided on a side of the detection shaft and detects and outputs the passage of the slit;
A control unit that receives an output from the stroke sensor;
The controller is
The position of the plunger is specified based on the output from the stroke sensor, and the movement distance of the plunger to the boosting chamber side is determined based on the specified position of the plunger,
The fuel injection pump, wherein the drive unit is controlled so that the plunger moves the determined moving distance.   2. The fuel injection pump according to claim 1, wherein the control unit uses a position of the plunger when the plunger reaches a position farthest from the boost chamber as a reference point for determining a movement distance of the plunger. . In the pump body, a hydraulic chamber to which hydraulic oil is supplied is formed on the end side of the plunger that is located on the opposite side of the boosting chamber,
The said drive part contains the 1st hydraulic solenoid valve which supplies the said hydraulic fluid in the said hydraulic chamber, and the 2nd hydraulic solenoid valve which permits discharge | emission of the said hydraulic fluid from the said hydraulic chamber. Fuel injection pump. An air chamber to which compressed air is supplied is formed in the pump body,
The fuel injection pump according to any one of claims 1 to 3, wherein the plunger is biased toward the hydraulic chamber by the compressed air in the air chamber.   The fuel injection pump according to claim 4, wherein the compressed air in the air chamber is discharged to the outside of the pump body through a space between an outer peripheral surface of the plunger and an inner peripheral surface of the pump main body.

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