JP2005344659A - Fuel injection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection apparatus capable of stably performing operations to boost a fuel by a boosting piston and inject the fuel. <P>SOLUTION: In the boosting piton 51, an area B1 pressed to a boosting chamber 34 side by a pressure in a pressurizing chamber 32 is set smaller than the sum of an area B3 pressed to a pressurizing chamber 32 side by a pressure in a boosting control chamber 33 and an area B4 pressed to the pressurizing chamber 32 side by a pressure in a boosting chamber 34. A back pressure chamber 54 into which the external atmospheric pressure is supplied is formed in the boosting device 5, and a face receiving a pressure in the back pressure chamber 54 to the boosting chamber 34 side is formed on the boosting piston 51. Thus, a force to return the boosting piston 51 to an initial position can be increased. Also, even if the back pressure chamber 54 is expanded by the movement of the boosting piston 51 to the boosting pressure chamber 34 side, the pressure in the back pressure chamber 54 can be prevented from being reduced to a negative pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection device, and more particularly, to a fuel injection device capable of injecting fuel supplied from a fuel supply source by increasing the pressure by a pressure increasing piston.

  An example of this type of fuel injection apparatus is disclosed in Patent Document 1. In Patent Document 1, there is provided a pressure increasing device capable of increasing the pressure of fuel delivered from a pump and injecting it by the operation of a pressure increasing piston. As shown in FIG. 11A, the pressure increasing device 105 presses the second pressure chamber 134 that is increased by the operation of the pressure increasing piston 151 and the pressure increasing piston 151 toward the second pressure chamber 134. The first pressure chamber 132 to which the pressure for supplying the pressure is supplied and the control chamber 133 to which the pressure for pressing the pressure-increasing piston 151 toward the first pressure chamber 132 is supplied and the supply pressure is controlled are formed. ing. The pressure-increasing piston 151 has a large diameter portion 151-1 that receives the pressure in the control chamber 133 toward the first pressure chamber 132 at one end, and the pressure in the second pressure chamber 134 at one end. The other end of the large-diameter portion 151-1 is connected to the other end, and the other end of the large-diameter portion 151-1 is connected to the other end of the first pressure chamber 132. Medium diameter part 151-3 which receives the pressure of 2 to the 2nd pressure chamber 134 side.

  In the pressure-increasing piston 151 having this configuration, the area pressed toward the second pressure chamber 134 by the pressure in the first pressure chamber 132 is pressed toward the first pressure chamber 132 by the pressure in the second pressure chamber 134. And the area that is pressed toward the first pressure chamber 132 by the pressure in the control chamber 133. As a result, when the operated boosting piston 151 is returned to the initial position, the force to the first pressure chamber 132 (upper side in FIG. 11) acting on the boosting piston 151 is increased, and the boosting piston 151 is moved to the initial position. The time required to return to the position is shortened.

  Moreover, the fuel injection apparatus of patent documents 2-4 is disclosed as other background art.

US Pat. No. 6,427,664 Japanese Patent No. 2885076 JP-A-8-277762 International Publication No. 02/14681 Pamphlet

  In Patent Document 1, as shown in FIG. 11B, when the pressure-increasing piston 151 is actuated to move toward the second pressure chamber 134 (the lower side in FIG. 11), the pressure-increasing piston 151 is moved. Accordingly, a negative pressure chamber 156 that becomes a negative pressure is generated between the side surface of the medium diameter portion 151-3 and the housing 157. The fuel leaks into the negative pressure chamber 156, which causes cavitation and erosion. In that case, the pressure vibration acts on the pressure-increasing piston 151, and the movement of the pressure-increasing piston 151 becomes irregular. Further, as shown in FIG. 11C, when the actuated boosting piston 151 returns to the first pressure chamber 132 side (upper side in FIG. 11), the fuel leaked into the negative pressure chamber 156 is increased. By being pressurized by 151, the pressure in the negative pressure chamber 156 increases. In this case, the fuel leaking into the negative pressure chamber 156 hinders the operation of returning the pressure increasing piston 151 to the initial position. Therefore, in patent document 1, there exists a problem that it is difficult to perform stably the operation | movement which pressurizes and injects fuel with the pressure increase piston 151. FIG.

  The present invention has been made in view of the above problems, and can prevent the generation of negative pressure accompanying the movement of the pressure-increasing piston, and can stably perform the operation of injecting fuel by increasing the pressure by the pressure-increasing piston. An object is to provide a fuel injection device.

  A fuel injection device according to the present invention includes an injection unit that injects fuel supplied from a fuel supply source to a fuel reservoir, a pressure increasing unit that increases the pressure of fuel supplied to the fuel reservoir by the operation of a pressure increasing piston, The pressure-increasing means communicates with the fuel reservoir, and is supplied from the fuel supply source with a pressure-increasing chamber that is pressurized by the operation of the pressure-increasing piston and a pressure for pressing the pressure-increasing piston toward the pressure-increasing chamber. And a control chamber in which a pressure for pressing the pressure increasing piston toward the pressure chamber is supplied and the pressure is controlled to control the operation of the pressure increasing piston. In the fuel injection device, with respect to the pressure increasing piston, the area pressed to the pressure increasing chamber side by the pressure in the pressure increasing chamber is equal to the area pressed to the pressure increasing chamber side by the pressure in the pressure increasing chamber and the pressure in the control chamber Is set smaller than the sum of the area pressed against the pressurizing chamber The pressure increasing means is further provided with a back pressure chamber to which a pressure higher than the atmospheric pressure is supplied, and the pressure increasing piston has a surface for receiving the pressure in the back pressure chamber toward the pressure increasing chamber. Is the gist.

  In the present invention, the pressure increasing means is formed with a back pressure chamber to which a pressure higher than atmospheric pressure is supplied, and the pressure increasing piston is provided with a surface for receiving the pressure in the back pressure chamber toward the pressure increasing chamber. Yes. As a result, even if the back pressure chamber expands by moving the pressure increasing piston to the pressure increasing chamber side, it is possible to prevent the pressure in the back pressure chamber from becoming negative, and cavitation and erosion due to negative pressure can be prevented. Occurrence can be prevented. And even if a back pressure chamber shrink | contracts because a pressure increase piston moves to the pressurization chamber side, the pressure rise in a back pressure chamber can be prevented. Therefore, according to the present invention, it is possible to stably perform the operation of injecting the fuel by increasing the pressure by the pressure increasing piston.

  In the fuel injection device according to the present invention, the back pressure chamber may be supplied with a pressure lower than the pressure of the fuel supply source. In this way, the force required to return the pressure boosting piston to the initial position during the return operation of the pressure boosting piston can be increased, so that the time required for the pressure boosting piston to return to the initial position can be shortened.

  In the fuel injection device according to the present invention of this aspect, atmospheric pressure can be supplied to the back pressure chamber. By doing so, the force required to return the pressure increasing piston to the initial position can be further increased during the returning operation of the pressure increasing piston, and therefore the time required for the pressure increasing piston to return to the initial position can be further shortened.

  The fuel injection device according to the present invention may further include back pressure control means for controlling the pressure in the back pressure chamber. In this way, the moving speed of the pressure increasing piston can be controlled.

  In the fuel injection device according to the present invention including the back pressure control means, the back pressure control means may increase the pressure in the back pressure chamber before the operation when the pressure increasing piston is operated. In this way, when the booster piston is operated, the force to the booster chamber acting on the booster piston can be increased, so that the fuel can be quickly boosted by the booster piston.

  In the fuel injection device according to the present invention having the back pressure control means, the back pressure control means may control the pressure in the back pressure chamber to be higher than the atmospheric pressure when the pressure increasing piston is operated. it can. In this way, when the booster piston is operated, the force to the booster chamber acting on the booster piston can be increased, so that the fuel can be quickly boosted by the booster piston.

  In the fuel injection device according to the present invention having the back pressure control means, the back pressure control means controls the pressure in the back pressure chamber to be the pressure of the fuel supply source when the pressure increasing piston is operated. You can also. In this way, the force to the pressure increasing chamber acting on the pressure increasing piston can be further increased during the operation of the pressure increasing piston, so that the pressure of the fuel can be increased more quickly by the pressure increasing piston.

  In the fuel injection device according to the present invention including the back pressure control means, the back pressure control means lowers the pressure in the back pressure chamber from before the movement when the pressure increasing piston moves toward the pressurizing chamber. You can also. By doing so, it is possible to increase the force for moving the pressure-increasing piston to the pressurizing chamber side during the returning operation of the pressure-increasing piston, and therefore it is possible to shorten the time required to return the pressure-increasing piston to the initial position. .

  In the fuel injection device according to the present invention having the back pressure control means, the back pressure control means is configured such that the pressure in the back pressure chamber is lower than the pressure of the fuel supply source when the pressure increasing piston moves toward the pressurizing chamber. It can also be controlled as follows. By doing so, it is possible to increase the force for moving the pressure-increasing piston to the pressurizing chamber side during the returning operation of the pressure-increasing piston, and therefore it is possible to shorten the time required to return the pressure-increasing piston to the initial position. .

  In the fuel injection device according to the present invention including the back pressure control means, the back pressure control means controls the pressure in the back pressure chamber to be the atmospheric pressure when the pressure increasing piston moves toward the pressurizing chamber. It can also be. In this way, the force for moving the boosting piston to the pressurizing chamber side can be further increased during the return operation of the boosting piston, so that the time required to return the boosting piston to the initial position can be further shortened. Can do.

  In the fuel injection device according to the present invention, the pressure increasing piston receives the pressure in the control chamber at one end toward the pressurizing chamber, and the large diameter portion receives the pressure in the back pressure chamber at the other end toward the pressure increasing chamber. One end receives the pressure in the pressure-increasing chamber toward the pressurizing chamber, the other end is connected to one end of the large diameter portion, the other end is connected to the other end of the large diameter portion, and the other end is pressurized And a medium-diameter portion that receives the pressure in the chamber toward the pressure-increasing chamber.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

“First Embodiment”
1 to 3 are diagrams showing an outline of the configuration of the fuel injection device according to the first embodiment of the present invention. FIG. 1 is an overall configuration, FIG. 2 is a configuration of a pressure booster, and FIG. The configuration is shown. The fuel injection device of this embodiment is applied to, for example, a compression ignition internal combustion engine, and includes a fuel pressurizing pump 1, a common pressure accumulation chamber (common rail) 2, and an injector 100. The injector 100 is provided corresponding to each cylinder, and includes a nozzle 6, an injection control valve 11, an injector internal pressure accumulation chamber 4, a pressure increase device 5, and a pressure increase control valve 18. Note that the fuel injection control using the fuel injection device of the present embodiment is executed by the controller 30.

  The fuel pressurizing pump 1 pumps up fuel stored in a tank (not shown) and supplies it to the common pressure accumulating chamber 2. The common pressure accumulating chamber 2 stores the fuel supplied from the fuel pressurizing pump 1 at a predetermined pressure. The pressure sensor 41 detects the fuel pressure (common rail pressure) in the common pressure accumulation chamber 2. The detected value of the pressure sensor 41 is input to the controller 30, and the controller 30 controls the regulator (not shown) provided in the common pressure accumulation chamber 2 so that the fuel pressure in the common pressure accumulation chamber 2 becomes the set pressure. Done. The set pressure here is, for example, a value of about 40 to 140 MPa, and a larger value is set in the controller 30 as the engine rotational speed and the required torque (drive load) are higher.

  The in-injector pressure accumulating chamber 4 to which fuel is supplied from the common pressure accumulating chamber 2 is a volume for connecting the pipe 3 and the pipes 19, 20, 21 in the injector 100, and a part or plural of the pipes You may comprise as a collection part of this pipe line.

  A fuel sump 7 is formed in the nozzle 6, and the fuel sump 7 is connected to the in-injector pressure accumulation chamber 4 via a pipe line 8, a pressure shut-off valve 17 and a pipe line 20, and the pipe lines 8, 9 is connected to the pressure booster 5 through 9. An injection hole 23 is formed in the seat portion 14 of the nozzle 6, and a needle 13 that opens and closes communication between the fuel reservoir 7 and the injection hole 23 is slidably accommodated in the nozzle 6.

  The operation of the needle 13 is performed by releasing the fuel pressure in the injector control chamber 10. Here, the injector control chamber 10 communicates with the in-injector pressure accumulation chamber 4 via the orifice 15, the pressure shut-off valve 17, and the pipe line 20, and communicates with the pressure booster 5 via the orifice 15 and the pipe line 9. doing. When fuel pressure is supplied to the injector control chamber 10, the needle 13 does not operate, and the fuel supplied from the common pressure accumulating chamber 2 to the fuel reservoir 7 is not injected.

  By operating the injection control valve 11, the fuel in the injector control chamber 10 is discharged through the orifice 16, and the command piston 12 and the needle 13 move toward the injector control chamber 10, and the fuel reservoir 7, the injection hole 23, Communicate. Thus, the fuel supplied from the common pressure accumulating chamber 2 to the fuel reservoir 7 is injected from the injection hole 23 into the combustion chamber of the internal combustion engine (not shown).

  Here, when the injection control valve 11 is operated without operating the pressure increasing device 5, the fuel supplied from the common pressure accumulating chamber 2 to the fuel reservoir 7 is injected without being increased in pressure. On the other hand, when the pressure increasing device 5 is operated and the injection control valve 11 is operated, the fuel supplied from the common pressure accumulating chamber 2 to the fuel reservoir 7 is increased in pressure and injected. As described above, the fuel injection device according to the present embodiment can inject the fuel supplied from the common pressure accumulation chamber 2 to the fuel reservoir 7 by increasing the pressure by the pressure increasing device 5.

  The pressure shut-off valve 17 is provided in order to prevent the fuel boosted by the pressure booster 5 from flowing back to the in-injector pressure accumulation chamber 4. Here, the pressure shut-off valve 17 allows the flow of fuel in the direction from the in-injector pressure accumulation chamber 4 to the fuel reservoir 7 and also checks to block the flow of fuel in the direction from the fuel reservoir 7 to the in-injector pressure accumulation chamber 4. It can be constituted by a valve.

  As shown in FIG. 2, the pressure increasing device 5 has a pressure increasing piston 51, and the pressure of the fuel stored in the fuel reservoir 7 can be increased by the operation of the pressure increasing piston 51. A pressurizing chamber 32, a pressure increasing chamber 34, and a pressure increasing control chamber 33 are formed in the pressure increasing device 5.

  The pressure increasing chamber 34 communicates with the fuel reservoir 7 through the pipe line 9 and the pipe line 8. Fuel is supplied to the pressure increasing chamber 34 from the common pressure accumulating chamber 2 via the in-injector pressure accumulating chamber 4 and the pressure shut-off valve 17. Further, fuel is supplied to the pressurizing chamber 32 from the common accumulator 2 through the in-injector accumulator 4. The fuel pressure in the pressurizing chamber 32 presses the pressure-increasing piston 51 toward the pressure-increasing chamber 34.

  The pressure increase control valve 18 communicates the pressure increase control chamber 33 and the in-injector pressure accumulation chamber 4 to supply the pressure of the fuel in the common pressure accumulation chamber 2 to the pressure increase control chamber 33, and the pressure increase control chamber. It is possible to switch between a second state in which the atmospheric pressure is supplied to the pressure-increasing control chamber 33 through communication between the external pressure sensor 33 and the external drain 22. By switching control of the pressure increase control valve 18, it is possible to switch between pressure supply / atmospheric release in the pressure increase control chamber 33. The fuel pressure in the pressure increasing control chamber 33 presses the pressure increasing piston 51 toward the pressurizing chamber 32.

  As shown in FIG. 3, the pressure increasing piston 51 includes a large-diameter portion 51-1 that receives the pressure of the fuel in the pressure increasing control chamber 33 toward the pressurizing chamber 32 at one end and the pressure increasing chamber 34 at one end. The other end of the large-diameter portion 51-1 is connected to the other end of the large-diameter portion 51-1, and the other end of the large-diameter portion 51-1 is connected to the other end. And the medium diameter part 51-3 for receiving the pressure of the fuel in the pressurizing chamber 32 toward the pressure increasing chamber 34. Here, the relationship of d1> d3> d2 is established regarding the outer diameter d1 of the large diameter portion 51-1, the outer diameter d2 of the small diameter portion 51-2, and the outer diameter d3 of the middle diameter portion 51-3. Due to this relationship, the area B1 of the surface where the pressure increasing piston 51 (the other end of the medium diameter portion 51-3) is pressed toward the pressure increasing chamber 34 by the pressure of the fuel in the pressure chamber 32 is the pressure increasing piston 51 ( The area B3 of the surface where one end of the large diameter portion 51-1) is pressed toward the pressurizing chamber 32 by the pressure of the fuel in the pressure increase control chamber 33, and the pressure increasing piston 51 (one end of the small diameter portion 51-2). It is set smaller than the sum of the area B4 of the surface pressed to the pressurizing chamber 32 side by the pressure of the fuel in the pressure increasing chamber 34. Since d3> d2, B1> B4.

  A back pressure chamber 54 is further formed in the pressure booster 5 of the present embodiment. The back pressure chamber 54 communicates with the external drain 22 through the orifice 55, so that atmospheric pressure is supplied to the back pressure chamber 54. The pressure increasing piston 51 receives the pressure (atmospheric pressure) of the fuel in the back pressure chamber 54 toward the pressure increasing chamber 34 at the other end of the large diameter portion 51-1. If the area of the surface where the pressure-increasing piston 51 (the other end of the large-diameter portion 51-1) receives the fuel pressure in the back pressure chamber 54 toward the pressure-increasing chamber 34 is B2, the relationship B1 + B2 = B3 + B4 is established. To do.

  The controller 30 performs pressure control in the common pressure accumulation chamber 2 so that the fuel pressure in the common pressure accumulation chamber 2 becomes the set pressure. The controller 30 controls the operation timing of the injection control valve 11 in order to control the fuel injection timing. Furthermore, the controller 30 also performs switching control of a pressure increase control valve 18 to be described later in order to inject fuel by increasing the pressure by the pressure increasing device 5.

  Next, the operation of the fuel injection device according to this embodiment will be described.

  During low load operation of the internal combustion engine, the fuel is injected by the pressure booster 5 without increasing the pressure. In that case, the injection control valve 11 is operated while the pressure increase control valve 18 remains in the first state.

  When the pressure increase control valve 18 is in the first state, the fuel pressure in the pressurization chamber 32, the pressure increase chamber 34, and the pressure increase control chamber 33 is the fuel pressure in the common pressure accumulation chamber 2 (common rail pressure). It is equal to. At this time, the pressure Fb1 acting on the other end of the medium diameter portion 51-3 due to the pressure in the pressurizing chamber 32 and the other end of the large diameter portion 51-1 due to the pressure in the back pressure chamber 54. The force Fb2 acting on the pressure-increasing chamber 34 side, the force Fb3 acting on the one end of the large-diameter portion 51-1 due to the pressure in the pressure-increasing control chamber 33, and the pressure in the pressure-increasing chamber 34 The relationship of Fb1 + Fb2 <Fb3 + Fb4 is established with respect to the force Fb4 to the pressurizing chamber 32 acting on one end of the small diameter part 51-2 by pressure. Therefore, the pressure increasing piston 51 is urged toward the pressurizing chamber 32 and is fixed at the initial position by a stopper (not shown). Therefore, when the pressure increase control valve 18 is in the first state, the pressure increase of the fuel by the pressure increase device 5 is not performed.

  On the other hand, during high load operation of the internal combustion engine, fuel is boosted by the pressure booster 5 and injected. In that case, the pressure increase control valve 18 is switched from the first state to the second state, and the injection control valve 11 is operated.

  When the pressure increase control valve 18 is switched from the first state to the second state, the pressure in the pressure increase control chamber 33 is reduced to atmospheric pressure. At this time, the force Fb1 + Fb2 acting on the pressure-increasing chamber 34 due to the pressure of the fuel exceeds the force Fb3 + Fb4 toward the pressurizing chamber 32, so that the pressure-increasing piston 51 is operated to increase the pressure-increasing chamber 34. Move to the side. As a result, the pressure of the fuel in the pressure increasing chamber 34 can be increased and the pressure of the fuel supplied to the fuel reservoir 7 can be increased, so that the fuel can be boosted and injected. B1 / B4 is the pressure increase ratio.

  When the pressure-increasing piston 51 operates and moves toward the pressure-increasing chamber 34, the volume of the back pressure chamber 54 increases. However, the back pressure chamber 54 communicates with the external drain 22, and external atmospheric pressure is supplied to the back pressure chamber 54. Therefore, the pressure in the back pressure chamber 54 is kept at atmospheric pressure, and the pressure in the back pressure chamber 54 is prevented from becoming smaller than the atmospheric pressure (becomes negative pressure). Therefore, the occurrence of cavitation and erosion due to negative pressure is prevented.

  Further, after the fuel is boosted and injected by the pressure booster 5, the pressure boosting piston 51 that has been operated is returned to the initial position. In that case, the pressure increase control valve 18 is switched from the second state to the first state.

  When the pressure increase control valve 18 is switched from the second state to the first state, the common rail pressure is supplied into the pressure increase control chamber 33. At this time, the force Fb3 + Fb4 acting on the pressure-increasing chamber 32 due to the fuel pressure exceeds the force Fb1 + Fb2 toward the pressure-increasing chamber 34, so that the pressure-increasing piston 51 moves toward the pressure chamber 32. To return to the initial position. Thus, in this embodiment, during the return operation of the pressure increasing piston 51, the force Fb3 + Fb4 to the pressurizing chamber 32 side due to the fuel pressure becomes larger than the force Fb1 + Fb2 to the pressure increasing chamber 34 side. The force for returning 51 to the initial position can be increased, and the time required to return the pressure-increasing piston 51 to the initial position can be shortened.

  When the pressure increasing piston 51 moves toward the pressurizing chamber 32 and returns to the initial position, the volume of the back pressure chamber 54 decreases. However, since the back pressure chamber 54 communicates with the external drain 22, the fuel in the back pressure chamber 54 is drained as the volume of the back pressure chamber 54 decreases. Therefore, the pressure in the back pressure chamber 54 is maintained at atmospheric pressure, and an increase in pressure due to a decrease in the volume of the back pressure chamber 54 is prevented.

  As described above, the operation of the pressure increasing piston 51 can be controlled by controlling the pressure in the pressure increasing control chamber 33 by switching control of the pressure increasing control valve 18.

  As described above, in the pressure increasing piston 51 of this embodiment, the area B1 pressed toward the pressure increasing chamber 34 by the pressure of the fuel in the pressurizing chamber 32 is the pressure of the fuel in the pressure increasing control chamber 33. Is set smaller than the sum of the area B3 of the surface pressed to the pressurizing chamber 32 side and the area B4 of the surface pressed to the pressurizing chamber 32 side by the fuel pressure in the pressure increasing chamber 34. Then, a back pressure chamber 54 to which an external atmospheric pressure is supplied is formed in the pressure increasing device 5, and a surface (atmospheric pressure) that receives the pressure (atmospheric pressure) in the back pressure chamber 54 toward the pressure increasing chamber 34 ( The other end of the large diameter portion 51-1 is provided. As a result, during the return operation of the pressure increasing piston 51, the force Fb3 + Fb4 acting on the pressure increasing piston 51 due to the pressure of the fuel is greater than the force Fb1 + Fb2 toward the pressure increasing chamber 34. The force to return 51 to the initial position can be increased. Therefore, the time required to return the pressure increasing piston 51 to the initial position can be shortened. Since the pressure increasing piston 51 can be reliably returned to the initial position by the pressure of the fuel without providing a spring for urging the pressure increasing piston 51 toward the pressurizing chamber 32, the spring can be omitted. Miniaturization of the pressure booster 5 can be realized.

  Furthermore, even if the back pressure chamber 54 is expanded by operating the pressure increasing piston 51 (moving toward the pressure increasing chamber 34) by supplying atmospheric pressure to the back pressure chamber 54, the pressure inside the back pressure chamber 54 is increased. It is possible to prevent the pressure from becoming smaller than atmospheric pressure (becomes negative pressure). Therefore, cavitation and erosion due to negative pressure can be prevented. And even if the back pressure chamber 54 shrinks by returning the pressure increasing piston 51 to the initial position (moving to the pressurizing chamber 32 side), it is possible to prevent the pressure inside the back pressure chamber 54 from increasing. Therefore, it is possible to prevent a decrease in force for returning the pressure increasing piston 51 to the initial position.

  From the above, according to the present embodiment, it is possible to stably perform the operation of injecting the fuel by increasing the pressure by the pressure increasing piston 51. Furthermore, the fuel can be injected by increasing the pressure by the pressure increasing piston 51 to a higher engine speed.

  In the above description of the present embodiment, the case where atmospheric pressure is supplied to the back pressure chamber 54 has been described. However, in the present embodiment, a pressure higher than the atmospheric pressure and lower than the pressure in the common pressure accumulation chamber 2 may be supplied to the back pressure chamber 54. Even in such a case, the force Fb3 + Fb4 to the pressurizing chamber 32 acting on the pressure increasing piston 51 by the pressure of the fuel can be made larger than the force Fb1 + Fb2 to the pressure increasing chamber 34 by the pressure of the fuel. The force for returning the pressure-increasing piston 51 to the initial position can be increased. Furthermore, it is possible to prevent the pressure in the back pressure chamber 54 from becoming negative when the pressure increasing piston 51 is operated.

“Second Embodiment”
4 and 5 are diagrams schematically showing the configuration of the fuel injection device according to the second embodiment of the present invention. FIG. 4 shows the overall configuration, and FIG. 5 shows the configuration of the pressure booster. In the present embodiment, a pressure regulator 61 capable of controlling the pressure in the back pressure chamber 54 is provided. The pressure regulator 61 adjusts the pressure of the fuel from the common pressure accumulation chamber 2 and supplies it to the back pressure chamber 54. A pressure control command value for controlling the pressure regulator 61 is output from the controller 30. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

  Also in the present embodiment, even if the back pressure chamber 54 is expanded by operating the pressure increasing piston 51 (moving toward the pressure increasing chamber 34 side), the back pressure is controlled by the pressure control in the back pressure chamber 54 by the pressure regulator 61. It is possible to prevent the pressure in the chamber 54 from becoming a negative pressure, and it is possible to prevent the occurrence of cavitation and erosion due to the negative pressure. Even if the back pressure chamber 54 is reduced by returning the pressure increasing piston 51 to the initial position (moving to the pressurizing chamber 32 side), the back pressure chamber 54 is controlled by the pressure regulator 61 to control the back pressure chamber 54. The pressure rise in 54 can be prevented.

  Furthermore, in this embodiment, since the pressure in the back pressure chamber 54 can be controlled by the pressure regulator 61, the force acting on the pressure increasing piston 51 can be controlled, and the moving speed of the pressure increasing piston 51 can be controlled. Can be controlled. Hereinafter, an example of pressure control in the preferable back pressure chamber 54 will be described.

  First, a case where the pressure of the fuel in the back pressure chamber 54 is maintained at a low pressure (for example, atmospheric pressure) by the pressure regulator 61 (case B) will be described. In this case, as in the first embodiment, when the booster piston 51 returns (moves to the pressurizing chamber 32 side), the force Fb3 + Fb4 acting on the pressurizing chamber 32 by the fuel pressure acts on the booster piston 51. Can be made larger than the force Fb1 + Fb2 to the pressure increasing chamber 34 side, the force for returning the pressure increasing piston 51 to the initial position can be increased. Therefore, as shown in case B of FIG. 6, the return speed of the pressure increasing piston 51 can be increased, and the time required to return the pressure increasing piston 51 to the initial position can be shortened.

  Next, the case where the pressure of the fuel in the back pressure chamber 54 is kept high (for example, the pressure in the common pressure accumulating chamber 2) by the pressure regulator 61 (case A) will be described. In that case, the force Fb1 + Fb2 acting on the pressure increasing chamber 34 acting on the pressure increasing piston 51 can be increased during the operation of the pressure increasing piston 51 (movement toward the pressure increasing chamber 34). Therefore, as shown in case A in FIG. 6, the moving speed of the pressure-increasing piston 51 toward the pressure-increasing chamber 34 can be increased, and the pressure increase speed in the pressure-increasing chamber 34 can be increased. The pressure increase of the fuel by the pressure piston 51 can be performed quickly.

  Next, when the pressure-increasing piston 51 is operated (moved toward the pressure-increasing chamber 34), the fuel pressure in the back pressure chamber 54 is increased from before the operation (for example, from atmospheric pressure to the pressure in the common pressure accumulating chamber 2). When the pressure of the fuel in the back pressure chamber 54 is lowered before the movement (for example, from the pressure in the common pressure accumulation chamber 2 to the atmospheric pressure) when the pressure increasing piston 51 is returned (moved toward the pressurizing chamber 32). (CaseC) will be described. In this case, the force Fb1 + Fb2 acting on the pressure-increasing chamber 34 acting on the pressure-increasing piston 51 can be increased when the pressure-increasing piston 51 is actuated (moved toward the pressure-increasing chamber 34). As shown, the moving speed of the pressure-increasing piston 51 toward the pressure-increasing chamber 34 can be increased, and the pressure increase speed in the pressure-increasing chamber 34 can be increased. Further, since the force for returning the pressure-increasing piston 51 to the initial position can be increased when the pressure-increasing piston 51 is returned (moved toward the pressurizing chamber 32), as shown in case C in FIG. The return speed of 51 can be increased. In case C, the moving speed (absolute value) of the pressure increasing piston 51 gradually increases when the pressure increasing piston 51 moves, and the time change rate (absolute value) of the pressure in the pressure increasing chamber 34 gradually increases. To do.

  As described above, in the present embodiment, when the pressure-increasing piston 51 is operated (moved toward the pressure-increasing chamber 34), the pressure in the back pressure chamber 54 is increased from before the operation, thereby increasing the pressure-increasing piston 51. It is possible to increase the force Fb1 + Fb2 acting on the pressure-increasing chamber 34 side. Therefore, the pressure increase of the fuel by the pressure increasing piston 51 can be performed quickly.

  In order to quickly increase the fuel pressure by the pressure increasing piston 51 when the pressure increasing piston 51 is operated, the pressure regulator 61 is controlled so that the pressure in the back pressure chamber 54 becomes the pressure in the common pressure accumulating chamber 2. It is particularly preferable to perform the control. However, even when the pressure regulator 61 is controlled so that the pressure in the back pressure chamber 54 is higher than the atmospheric pressure and lower than the pressure in the common pressure accumulation chamber 2 when the pressure increasing piston 51 is operated, the pressure increasing piston 51 Fuel pressure can be increased quickly.

  In the present embodiment, when the pressure increasing piston 51 is returned (moved toward the pressurizing chamber 32), the pressure in the back pressure chamber 54 is decreased from before the movement, so that the pressure increasing piston 51 is returned to the initial position. The returning force can be increased. Therefore, the time required to return the pressure increasing piston 51 to the initial position can be shortened.

  In order to reduce the time required for returning the booster piston 51 to the initial position when the booster piston 51 returns, the pressure regulator 61 is controlled so that the pressure in the back pressure chamber 54 becomes atmospheric pressure. It is particularly preferred to do this. However, even when the pressure regulator 61 is controlled so that the pressure in the back pressure chamber 54 is higher than the atmospheric pressure and lower than the pressure in the common pressure accumulation chamber 2 when the pressure increasing piston 51 returns, The time required to return to the initial position can be shortened.

  In the present embodiment, the pressure in the back pressure chamber 54 may be controlled by the switching valve 62 as shown in FIGS. The switching valve 62 communicates the back pressure chamber 54 with the in-injector pressure accumulation chamber 4 to supply the fuel pressure in the common pressure accumulation chamber 2 to the back pressure chamber 54, and the back pressure chamber 54 and the external drain. 22 is switched to the second state in which the atmospheric pressure is supplied to the back pressure chamber 54 through communication. Switching control of the switching valve 62 is performed by a control command value output from the controller 30.

  7 and 8, when the pressure increasing piston 51 is operated (moved toward the pressure increasing chamber 34), the pressure increasing chamber acting on the pressure increasing piston 51 is switched by switching the switching valve 62 to the first state. The force Fb1 + Fb2 toward the side 34 can be increased, and the fuel pressure can be quickly increased by the pressure-increasing piston 51. When the booster piston 51 is returned (moved toward the pressurizing chamber 32), the switching valve 62 is switched to the second state, whereby the force for returning the booster piston 51 to the initial position can be increased. The time required to return the pressure piston 51 to the initial position can be shortened.

  In the description of each of the above embodiments, the injector 100 is provided with the in-injector pressure accumulation chamber 4 and the common pressure accumulation chamber 2 and the injector 100 (injector pressure accumulation chamber 4) are connected by a single pipe 3. explained. However, in each embodiment, the common pressure accumulation chamber 2 and the injector 100 may be connected by a plurality of pipelines. As an example, FIGS. 9 and 10 show a case where the common pressure accumulating chamber 2 and the injector 100 are connected by three pipelines 19, 20, and 21. 9 shows the case of the first embodiment in which the back pressure chamber 54 communicates with the drain 22, and FIG. 10 shows the second embodiment in which the pressure in the back pressure chamber 54 can be controlled by the pressure regulator 61. The case of form is shown.

  In the description of each of the above embodiments, the case where the pressure increase control valve 18 and the injection control valve 11 are provided separately and the fuel pressure increase and injection are controlled independently has been described. However, in each embodiment, these two control valves 11 and 18 may be combined into one, and fuel pressure increase and injection may be controlled by one control valve. In the configuration of each embodiment in which fuel pressure increase and injection are controlled by a single control valve, pilot injection, post injection, or the like is used up to a higher engine rotational speed by using the stepped pressure increasing piston 51 of this time. Split injection can be performed, and the application range of split injection can be expanded.

  In each embodiment, a plurality of back pressure chambers 54 may be formed in the pressure booster 5. The pressure increasing piston 51 may be provided with a plurality of surfaces that receive the pressure in the back pressure chamber 54 toward the pressure increasing chamber 34.

  1, 2, 4, 5, 7 to 10, the pressure increase control valve 18 and the switching valve 62 (in the case of FIGS. 7 and 8) are shown as three-way valves, but a two-way valve type is used. May be. And in the pressure booster 5 of each embodiment, although the spring which urges | biases the pressure boosting piston 51 to the pressurization chamber 32 side can be omitted in principle, you may provide a spring auxiliary. . Even when the pressure booster 5 of each embodiment is provided with a spring, the spring can be downsized, and the pressure booster 5 can be downsized.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

It is a figure which shows the outline of a structure of the fuel-injection apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the outline of a structure of the pressure booster in 1st Embodiment of this invention. It is a figure which shows the outline of a structure of the pressure increase piston in 1st Embodiment of this invention. It is a figure which shows the outline of a structure of the fuel-injection apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the outline of a structure of the pressure booster in 2nd Embodiment of this invention. It is a figure which shows the displacement of the pressure increase piston with respect to the pressure in a back pressure chamber, and the pressure in a pressure increase chamber. It is a figure which shows the outline of the other structure of the fuel-injection apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the outline of the other structure of the pressure booster in 2nd Embodiment of this invention. It is a figure which shows the outline of the other structure of the fuel-injection apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the outline of the other structure of the fuel-injection apparatus which concerns on 2nd Embodiment of this invention. It is a figure explaining the outline of the structure of the conventional pressure booster, and its subject.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel pressurization pump, 2 Common pressure accumulation chamber, 3, 8, 9, 19, 20, 21 Pipe line, 4 Injector pressure accumulation chamber, 5 Pressure booster, 6 Nozzle, 7 Fuel reservoir, 10 Injector control chamber, 11 Injection Control valve, 13 Needle, 17 Pressure shut-off valve, 18 Pressure increase control valve, 22 Drain, 23 Injection hole, 30 Controller, 32 Pressure chamber, 33 Pressure increase control chamber, 34 Pressure increase chamber, 51 Pressure increase piston, 54 Back Pressure chamber, 55 orifice, 61 pressure regulator, 62 switching valve, 100 injector.

Claims (11)

An injection means for injecting fuel supplied from a fuel supply source to the fuel reservoir, and a pressure increasing means for increasing the pressure of the fuel supplied to the fuel reservoir by the operation of the pressure increasing piston;
For pressure increasing means,
A pressure-increasing chamber that communicates with the fuel reservoir and is pressurized by the operation of the pressure-increasing piston;
A pressurizing chamber to which pressure for pressing the boosting piston toward the boosting chamber is supplied from a fuel supply source;
A control chamber in which a pressure for pressing the pressure increasing piston toward the pressurizing chamber is supplied, and the pressure is controlled to control the operation of the pressure increasing piston;
Is a fuel injection device formed,
Regarding the pressure boosting piston, the area pressed to the pressure increasing chamber side by the pressure in the pressurizing chamber is pressed to the pressure chamber side by the pressure in the pressure increasing chamber and the area pressed to the pressure chamber side by the pressure in the control chamber. Is set smaller than the sum of the area to be
The pressure increasing means is further formed with a back pressure chamber to which a pressure higher than atmospheric pressure is supplied, and the pressure increasing piston is provided with a surface for receiving the pressure in the back pressure chamber toward the pressure increasing chamber. A fuel injection device. The fuel injection device according to claim 1,
A fuel injection device, wherein a pressure lower than a pressure of a fuel supply source is supplied to the back pressure chamber. The fuel injection device according to claim 2,
A fuel injection device characterized in that atmospheric pressure is supplied to the back pressure chamber. The fuel injection device according to claim 1,
A fuel injection device further comprising back pressure control means for controlling the pressure in the back pressure chamber. The fuel injection device according to claim 4,
The back pressure control means increases the pressure in the back pressure chamber from before the operation when the pressure increasing piston is operated. The fuel injection device according to claim 4,
The back pressure control means controls the pressure in the back pressure chamber to be higher than the atmospheric pressure when the pressure increasing piston is operated. The fuel injection device according to claim 6,
The back pressure control means controls the pressure in the back pressure chamber so as to become the pressure of the fuel supply source when the pressure increasing piston is operated. The fuel injection device according to claim 4,
The back pressure control means lowers the pressure in the back pressure chamber from before the movement when the pressure increasing piston moves toward the pressurizing chamber. The fuel injection device according to claim 4,
The back pressure control means controls the pressure in the back pressure chamber to be lower than the pressure of the fuel supply source when the booster piston moves toward the pressurizing chamber. The fuel injection device according to claim 9, wherein
The back pressure control means controls the pressure in the back pressure chamber to be an atmospheric pressure when the booster piston moves to the pressurizing chamber side. The fuel injection device according to any one of claims 1 to 10,
Booster piston
A large-diameter portion that receives the pressure in the control chamber at one end toward the pressurizing chamber and receives the pressure in the back pressure chamber at the other end toward the pressure-increasing chamber;
Receiving the pressure in the pressure-increasing chamber at one end to the pressurizing chamber side, and a small diameter portion in which one end of the large diameter portion is connected to the other end;
The other end of the large-diameter portion is connected to one end, and the other end of the large-diameter portion receives the pressure in the pressurizing chamber toward the pressure-increasing chamber.
A fuel injection device comprising:

Images