JP2019027291A - Common rail assembly and method for assembling the same - Google Patents

Abstract

To provide a common rail assembly which can achieve miniaturization, and can improve a degree of freedom of an engine layout.SOLUTION: In a common rail assembly 1, a flow limiter is attached to each of distribution bores of a common rail 10. In the common rail assembly 1, a recession 17 communicated with a branch flow passage 16 is formed in the distribution bore 15 of the common rail 10. A seat block 40 having an outlet flow passage 45 and a seat 43 is attached to the vicinity of an opening of the recession 17. A valve piston 31 which can be seated on the seat 43 and a spring 50 which presses the valve piston 31 to a side separating from the seat block 40 are stored in the recession 17.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a common rail assembly in which a flow limiter is attached to a common rail, and a method for assembling the common rail assembly.

FIG. 9 is a configuration diagram illustrating an example of a conventional common rail injection system.
Conventionally, a common rail injection system 100 shown in FIG. 9 is known as a fuel injection system used in a diesel engine. The common rail injection system 100 includes a high-pressure pump 102, a common rail 210, and a plurality of injectors 105 (fuel injection valves).

  The high-pressure pump 102 pressurizes the fuel stored in the fuel tank 101 to form high-pressure fuel, and supplies (pressure-feeds) the fuel to the common rail 210. Specifically, the discharge port of the high-pressure pump 102 is connected to the suction port 213 of the common rail 210 via the pipe 103. That is, the high-pressure pump 102 pressurizes the fuel in the fuel tank 101 to form high-pressure fuel, and supplies the high-pressure fuel to the common rail 210 through the pipe 103.

  The common rail 210 stores high-pressure fuel supplied from the high-pressure pump 102 in an internal space of the common rail main body 211 (see an internal space 212 in FIGS. 2 and 3 described later). The common rail 210 distributes and supplies the high-pressure fuel stored in the common rail body 211 to each injector 105. Specifically, a plurality of distribution bore portions 215 corresponding to the number of injectors 105 are provided on the outer peripheral portion of the common rail main body 211. Each of the distribution bore portions 215 is formed with a distribution channel (see a distribution channel 216 in FIGS. 2 and 3 to be described later) communicating with the internal space of the common rail body 211. Each of the distribution bore portions 215 is connected to the injector 105 by a supply pipe 104. Thereby, the high-pressure fuel stored in the common rail main body 211 is supplied to each injector 105 via the distribution flow path and the supply pipe 104 of the distribution bore portion 215.

  Each of the injectors 105 is provided for each cylinder of the engine. Each of the injectors 105 injects high-pressure fuel supplied from the common rail body 211 via the distribution flow path of the distribution bore section 215 and the supply pipe 104 into the combustion chamber of each cylinder. Each injector 105 is connected to the fuel tank 101 by a return pipe 106. Of the fuel supplied to the injector 105, the fuel that has not been injected into the combustion chamber is returned to the fuel tank 101 via the return pipe 106.

  In the common rail injection system 100 configured as described above, the flow limiter 230 may be attached to each distribution bore portion 215 of the common rail 210 in case the supply pipe 104 is damaged. That is, the distribution bore part 215 and the supply pipe 104 may be connected via the flow limiter 230. These flow limiters 230 are connected to the outside of the common rail 210 from the distribution flow path of the distribution bore section 215 when the flow rate of the fuel flowing out of the distribution flow path of the distribution bore section 215 exceeds the specified flow rate. It stops fuel outflow. Thereby, even when the supply pipe 104 is damaged, it is possible to prevent the fuel from leaking out of the common rail injection system 100.

  When manufacturing the common rail injection system 100 including the flow limiter 230, first, the flow limiter 230 is attached to each distribution bore portion 215 of the common rail 210 to complete the common rail assembly 201. Then, the common rail assembly 201 is attached to the engine room of the vehicle body. Thereafter, the common rail assembly 201, the high-pressure pump 102, the plurality of injectors 105, and the fuel tank 101 are connected by piping to complete the common rail injection system 100.

  FIG. 10 is an overall view showing a conventional common rail assembly. Further, FIG. 11 is an enlarged view of a main part showing the periphery of the flow limiter of the conventional common rail assembly in cross section. FIG. 10 shows a partial range in cross section. Further, the cross section of FIG. 10 shows the distribution bore portion 215 in a state where the flow limiter 230 is not attached so that the configuration of the distribution bore portion 215 can be easily seen.

  The common rail assembly 201 includes a common rail 210 and a plurality of flow limiters 230. The common rail 210 includes a common rail main body 211 and a plurality of distribution bore portions 215 provided on the outer peripheral portion of the common rail main body 211. The common rail body 211 has an internal space 212 for storing fuel. The common rail body 211 is also formed with a suction port 213 communicating with the internal space 212. As shown in FIG. 9, the suction port 213 is connected to the high-pressure pump 102 via the pipe 103. That is, the high-pressure fuel supplied from the high-pressure pump 102 flows into the internal space 212 through the suction port 213 and is stored in the internal space 212. Each of the distribution bore portions 215 is formed with a distribution flow path 216 communicating with the internal space 212 of the common rail body 211. Each of the distribution bore portions 215 is formed with a female screw 217 for attaching the flow limiter 230 to the end of the distribution flow channel 216.

  The flow limiter 230 includes a valve housing 240, a bush 260, a valve piston 231, and a spring 250. The valve housing 240 is formed with, for example, a cylindrical recess 246 that opens to the first end 241. The valve housing 240 is formed with an outlet channel 245 that communicates the bottom of the recess 246 with the second end 242. The valve housing 240 has a seat portion 243 on which a distal end portion of a convex portion 233 of the valve piston 231 described later is seated at a communication portion between the concave portion 246 and the outlet flow path 245. In the valve housing 240, a male screw 247 is formed on the outer peripheral portion of the first end portion 241, and a male screw 248 is formed on the outer peripheral portion of the second end portion 242. The male screw 247 is used when the flow limiter 230 is attached to the distribution bore portion 215 of the common rail 210. The male screw 248 is used when connecting the supply pipe 104 to the flow limiter 230.

  The bush 260 is provided in the opening of the recess 246 of the valve housing 240. The bush 260 is fixed by press-fitting it into the recess 246, for example. The bush 260 is formed with an inlet channel 261 that communicates the distribution channel of the distribution bore 215 and the recess 246 of the valve housing 240.

  The valve piston 231 is accommodated in the recess 246 of the valve housing 240 so as to be able to reciprocate. The valve piston 231 includes, for example, a cylindrical sliding portion 232 whose outer peripheral surface slides with the inner peripheral surface of the recess 246. Further, the valve piston 231 includes a convex portion 233 that protrudes from the sliding portion 232 toward the seat portion 243. That is, when the valve piston 231 moves in the concave portion 246 toward the seat portion 243, the valve piston 231 stops when the tip end portion of the convex portion 233 is seated on the seat portion 243. Further, when the valve piston 231 moves in the recess 246 toward the bush 260, the valve piston 231 stops when the end of the sliding portion 232 comes into contact with the bush 260.

  A communication flow path 235 is formed in the valve piston 231. In the recess 246, the communication channel 235 communicates the space closer to the bush 260 than the sliding portion 232 and the space closer to the seat portion 243 than the sliding portion 232. The communication channel 235 includes, for example, a recess 236 and an orifice 237. The concave portion 236 opens at the end of the sliding portion 232 on the bush 260 side and extends to the vicinity of the tip of the convex portion 233. The orifice 237 communicates the outer peripheral side space of the convex portion 233 and the concave portion 236.

  The spring 250 presses the valve piston 231 in a direction away from the seat portion 243. The spring 250 is disposed between the bottom portion of the recess 246 and the sliding portion 232 of the valve piston 231 in a state where the spring 250 is contracted from the natural length.

  The flow limiter 230 configured as described above is attached to each distribution bore portion 215 of the common rail 210. Specifically, the flow limiter 230 is attached to the distribution bore portion 215 by screwing a male screw 247 formed at the first end 241 of the valve housing 240 of the flow limiter 230 into the female screw 217 of the distribution bore portion 215.

  Next, the operation of the conventional common rail assembly 201 incorporated in the common rail injection system will be described.

12 and 13 are sectional views showing the periphery of the flow limiter of the conventional common rail assembly, and are diagrams for explaining the operation of the common rail assembly.
The high-pressure fuel supplied from the high-pressure pump 102 to the internal space 212 of the common rail main body 211 passes through the distribution flow path 216, the inlet flow path 261, and the communication flow path 235, and the seat portion 243 rather than the sliding portion 232 in the recess 246. Flows into the side space. Hereinafter, the space closer to the sheet portion 243 than the sliding portion 232 in the recess 246 is referred to as an outlet-side space 246a of the recess 246.

  In a state where fuel is not injected from the injector 105, the outlet-side space 246a of the recess 246 is filled with high-pressure fuel and has a pressure equivalent to that of the space upstream of the outlet-side space 246a in the fuel flow direction. It becomes. In other words, the outlet-side space 246 a of the recess 246 has a pressure equivalent to that of the high-pressure fuel existing in the internal space 212, the distribution channel 216, the inlet channel 261, and the communication channel 235. For this reason, as shown in FIG. 11, the valve piston 231 is pressed by the spring 250 and is in contact with the bush 260.

  When fuel is injected from the injector 105, the high-pressure fuel in the supply pipe 104 connected to the injector 105 flows out toward the injector 105. Since the supply pipe 104 communicates with the outlet-side space 246 a of the recess 246, high-pressure fuel existing in the outlet-side space 246 a of the recess 246 also flows out to the supply pipe 104 through the outlet channel 245. When the high pressure fuel flows out from the outlet side space 246 a of the recess 246, the pressure in the outlet side space 246 a becomes lower than the pressure in the internal space 212 of the common rail body 211. For this reason, the high-pressure fuel supplied from the high-pressure pump 102 to the internal space 212 of the common rail body 211 flows into the outlet-side space 246 a of the recess 246 through the distribution flow path 216, the inlet flow path 261, and the communication flow path 235. .

  Here, the orifice 237 of the communication channel 235 is set such that the flow rate of the fuel flowing out from the outlet side space 246a is larger than the flow rate of the fuel flowing into the outlet side space 246a of the recess 246. . For this reason, while the fuel is being injected from the injector 105, the pressure in the outlet side space 246a of the recess 246 gradually decreases. Therefore, a pressure difference is generated between the outlet side space 246a of the concave portion 246 and the space (the concave portion 236 or the like) on the upstream side in the fuel flow direction from the outlet side space 246a. A force according to this pressure difference acts on the valve piston 231. For this reason, as shown in FIG. 12, while fuel is being injected from the injector 105, the valve piston 231 reaches a position where the force acting on the valve piston 231 according to this pressure difference balances with the pressing force of the spring 250. Move to the sheet portion 243 side. Hereinafter, the pressure difference between the outlet side space 246a of the concave portion 246 and the space (the concave portion 236 and the like) on the upstream side in the fuel flow direction from the outlet side space 246a is referred to as a pressure difference A.

  When the fuel injection from the injector 105 is finished, the outflow of fuel from the outlet side space 246a of the recess 246 is also finished. For this reason, when the high-pressure fuel in the internal space 212 of the common rail body 211 flows into the outlet-side space 246a of the recess 246, the pressure difference A decreases. As the pressure difference A decreases, the valve piston 231 is pushed toward the bush 260 by the spring 250. Finally, as shown in FIG. 11, the valve piston 231 stops in contact with the bush 260.

  When the supply pipe 104 is damaged, the flow rate of the fuel flowing out from the outlet side space 246a of the recess 246 becomes larger than that during the fuel injection of the injector 105. For this reason, when the supply pipe 104 is damaged, the pressure difference A becomes larger than when the injector 105 injects fuel. For this reason, as shown in FIG. 13, the valve piston 231 moves to the moving end on the seat portion 243 side, and the tip of the convex portion 233 of the valve piston 231 is seated on the seat portion 243. As a result, the outlet channel 245 is closed and fuel does not flow out of the flow limiter 230. That is, the flow limiter 230 is closed. In the present specification, the pressing force of the spring applied to the valve piston in a state where the valve piston is seated on the seat portion is referred to as a valve closing load. In other words, in this specification, the pressing force of the spring applied to the valve piston in the valve closed state is referred to as a valve closing load.

JP 2004-27966 A

  As described above, in the conventional common rail assembly 201, the flow limiter 230 is distributed by screwing the male screw 247 formed at the first end 241 of the flow limiter 230 into the female screw 217 of the distribution bore portion 215. Attached to the bore 215. For this reason, in the conventional common rail assembly 201, most of the flow limiter 230 protrudes from the common rail 210. For this reason, when the conventional common rail assembly 201 is attached to the engine room, it is necessary to secure a large installation space for the common rail assembly 201. Therefore, the conventional common rail assembly 201 has a problem of restricting the degree of freedom in engine layout.

  The present invention has been made to solve the above-described problems, and a first object thereof is to provide a common rail assembly that can be reduced in size and can improve the degree of freedom in engine layout. A second object of the present invention is to provide a method for assembling the common rail assembly.

  A common rail assembly according to the present invention includes a common rail main body in which an internal space in which fuel is stored is formed, and a plurality of distribution channels that are provided on an outer peripheral portion of the common rail main body and communicate with the internal space. A common rail having a distribution bore portion and a common rail attached to each of the distribution bore portions, and when the flow rate of fuel flowing out of the common rail from the distribution flow channel becomes equal to or higher than a predetermined flow rate, from the distribution flow channel to the common rail. And a flow limiter for stopping the outflow of fuel to the outside of the common rail assembly, wherein the distribution bore portion of the common rail is formed with a recessed portion whose bottom communicates with the distribution flow path. The limiter is reciprocally accommodated in the recess and has a sliding portion whose outer peripheral surface slides with the inner peripheral surface of the recess. A valve piston having a communication flow path communicating the space on the bottom side with respect to the sliding portion and the space on the opening side of the concave portion with respect to the sliding portion; and the valve piston in the concave portion with respect to the valve piston. It is a surface on the opposite side of the first surface from the first surface side which is attached to the opening side and has a seat portion on which the valve piston is seated and which faces the valve piston. A seat block formed with an outlet channel penetrating on the second surface side, a spring provided between the sliding portion and the seat block and pressing the valve piston in a direction away from the seat block; When the valve piston is seated on the seat portion, the outlet passage is closed, and the outflow of fuel from the distribution passage to the outside of the common rail is stopped.

  Here, in the common rail assembly according to the present invention, the seat block may be press-fitted into the recess.

  Further, in the common rail assembly according to the present invention, the seat portion may have a tapered shape whose diameter decreases from the first surface side toward the second surface side.

  Further, in the common rail assembly according to the present invention, when the seat blocks of the two flow limiters are compared, the position where the valve piston is seated in the seat portion and the first seat in the direction orthogonal to the first surface. The distance between the surfaces may be different.

  Further, in the common rail assembly according to the present invention, the flow limiter has a plurality of the seat blocks, and each of the plurality of seat blocks is in a direction orthogonal to the first surface. The distance between the seat portion where the valve piston is seated and the first surface may be different, and one of the plurality of seat blocks may be attached to the recess.

  In the assembly method of the common rail assembly according to the present invention, the distance between the seating portion of the seat portion where the valve piston is seated and the first surface is different in the direction orthogonal to the first surface. A block is prepared, and one of the plurality of seat blocks is attached to the recess, and the spring pressing force applied to the valve piston is adjusted in a state where the valve piston is seated on the seat portion. To do.

  In the common rail assembly according to the present invention, the distribution bore portion of the common rail has a partial function of the valve housing 240 of the conventional flow limiter 230, and the flow limiter is accommodated in the recess of the distribution bore portion. For this reason, since the flow limiter does not protrude from the common rail, the common rail assembly according to the present invention can be miniaturized. Therefore, the common rail assembly according to the present invention can improve the degree of freedom in engine layout.

  Here, it is possible to further prevent the fuel leak from occurring between the seat block and the recess by press-fitting and fixing the seat block into the recess of the distribution bore portion. That is, in the state where the valve piston is seated on the seat portion, the outflow of fuel from the distribution flow path to the outside of the common rail can be stopped more reliably.

  Further, by forming the seat portion in a tapered shape, it is possible to further prevent a fuel leak from occurring between the seat portion and the valve piston when the valve piston is seated on the seat portion. That is, in the state where the valve piston is seated on the seat portion, the outflow of fuel from the distribution flow path to the outside of the common rail can be stopped more reliably.

  Further, in the method for assembling the common rail assembly according to the present invention, the distance between the position where the valve piston is seated in the seat portion and the first surface in the direction orthogonal to the first surface is made different, thereby closing the spring valve. The time load can be adjusted. Thereby, the prescribed flow rate when stopping the outflow of fuel from the distribution flow path to the outside of the common rail can be adjusted. Thus, in the common rail assembly according to the present invention in which the load when the spring is closed is adjusted, when the seat blocks of the two flow limiters are compared, the valve piston in the seat portion is seated in the direction orthogonal to the first surface. The distance between the place to be performed and the first surface may be different.

  Further, the common rail assembly according to the present invention provides a plurality of seats having different distances between the first surface and a position where the valve piston is seated in the seat portion in a direction orthogonal to the first surface with respect to one flow limiter. A block may be provided. Thereby, for example, the purchaser of the common rail assembly according to the present invention can adjust the valve closing load of the spring after the purchase of the common rail assembly.

1 is an overall view showing a common rail assembly according to an embodiment of the present invention. It is the principal part enlarged view which showed the flow limiter periphery of the common rail assembly which concerns on embodiment of this invention in the cross section. It is sectional drawing which shows the flow limiter periphery of the common rail assembly which concerns on embodiment of this invention, and is a figure for demonstrating operation | movement of a common rail assembly. It is sectional drawing which shows the flow limiter periphery of the common rail assembly which concerns on embodiment of this invention, and is a figure for demonstrating operation | movement of a common rail assembly. In the flow limiter which concerns on embodiment of this invention, it is a figure for demonstrating the adjustment method of the flow volume of the fuel at the time of obstruct | occluding an exit flow path, and is sectional drawing of a seat block. It is the principal part enlarged view which showed the flow limiter periphery of another example of the common rail assembly which concerns on embodiment of this invention in the cross section. It is the principal part enlarged view which showed the flow limiter periphery of another example of the common rail assembly which concerns on embodiment of this invention in the cross section. It is the principal part enlarged view which showed the flow limiter periphery of another example of the common rail assembly which concerns on embodiment of this invention in the cross section. It is a block diagram which shows an example of the conventional common rail injection system. It is a general view which shows the conventional common rail assembly. It is the principal part enlarged view which showed the flow limiter periphery of the conventional common rail assembly in the cross section. It is sectional drawing which shows the flow limiter periphery of the conventional common rail assembly, and is a figure for demonstrating operation | movement of a common rail assembly. It is sectional drawing which shows the flow limiter periphery of the conventional common rail assembly, and is a figure for demonstrating operation | movement of a common rail assembly.

Embodiment.
Hereinafter, embodiments relating to the common rail assembly according to the present invention will be described in detail. However, this embodiment shows one aspect of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.

  FIG. 1 is an overall view showing a common rail assembly according to an embodiment of the present invention. FIG. 2 is an enlarged view of a main part showing a cross section of the periphery of the flow limiter of the common rail assembly according to the embodiment of the present invention. FIG. 1 shows a partial range in cross section. Further, in the cross section of FIG. 1, the distribution bore portion 15 in a state where the flow limiter 30 is not attached is shown so that the configuration of the distribution bore portion 15 can be easily seen.

  The common rail assembly 1 includes a common rail 10 and a plurality of flow limiters 30. The common rail 10 includes a common rail main body 11 and a plurality of distribution bore portions 15 provided on the outer peripheral portion of the common rail main body 11. The common rail body 11 is formed with an internal space 12 for storing fuel. The common rail body 11 is also formed with a suction port 13 that communicates with the internal space 12. The suction port 13 is connected to one end of a pipe connected to a high-pressure pump. For example, in the common rail injection system 100 shown in FIG. 9, when the common rail assembly 1 according to the present embodiment is used instead of the conventional common rail assembly 201, the suction port 13 is connected to the pipe 103. That is, the high-pressure fuel supplied from the high-pressure pump flows into the internal space 12 through the suction port 13 and is stored in the internal space 12.

  Each of the distribution bore portions 15 is formed with a distribution channel 16 communicating with the internal space 12 of the common rail body 11. Further, each of the distribution bore portions 15 is formed with a concave portion 17 in which the bottom portion 18 communicates with the distribution flow path 16. The male screw 19 formed on the outer peripheral portion of the distal end portion of the distribution bore portion 15 is used when connecting the piping connected to the injector and the distribution bore portion 15. For example, in the common rail injection system 100 shown in FIG. 9, when the common rail assembly 1 according to this embodiment is used instead of the conventional common rail assembly 201, the male screw 19 is connected to the supply pipe 104, the distribution bore portion 15, and the like. Used when connecting.

  The flow limiter 30 is attached to the distribution bore portion 15. Further, the flow limiter 30 is connected to the common rail 10 from the distribution flow path 16 of the distribution bore section 15 when the flow rate of the fuel flowing out of the distribution flow path 16 of the distribution bore section 15 to the outside of the common rail 10 becomes equal to or higher than the specified flow volume Q. This stops fuel outflow from the outside. In the present embodiment, the flow limiter 30 is accommodated in the concave portion 17 of the distribution bore portion 15. That is, in the common rail assembly 1 according to the present embodiment, the distribution bore portion 15 has a partial function of the valve housing 240 of the conventional flow limiter 230.

  Specifically, the flow limiter 30 includes a seat block 40, a valve piston 31, and a spring 50. The seat block 40 is attached to a portion of the concave portion 17 of the distribution bore portion 15 that is closer to the opening side of the concave portion 17 than the valve piston 31. The seat block 40 has an outlet passage 45 that penetrates from the first surface 41 side that is the surface facing the valve piston 31 to the second surface 42 side that is the surface opposite to the first surface 41. Is formed. The seat block 40 has a seat portion 43 on which a later-described corner portion 34 of the valve piston 31 is seated. A later-described corner portion 34 of the valve piston 31 is seated at a seat position 44 of the seat portion 43. The sheet position 44 has a circular shape with a diameter D that surrounds the opening of the outlet channel 45.

  In the present embodiment, the seat block 40 is press-fitted into the concave portion 17 and fixed to the concave portion 17. By attaching the seat block 40 to the recess 17 by press-fitting, it is possible to reliably prevent the fuel leak from occurring between the seat block 40 and the recess 17. That is, in a state where the valve piston 31 is seated on the seat portion 43, the outflow of fuel from the distribution channel 16 to the outside of the common rail 10 can be stopped more reliably. Here, in order to prevent the seat block 40 and the valve piston 31 from interfering with each other when the seat block 40 is press-fitted, the seat block 40 is fixed using a jig (not shown) that can position the seat block 40 during press-fitting. It is preferable to press fit into the recess 17.

  Further, in the present embodiment, the sheet portion 43 has a tapered shape with a diameter that decreases from the first surface 41 side toward the second surface 42 side. Such a shape of the seat portion 43 is a shape that has a proven track record as a seat portion shape that opens and closes a flow path through which high-pressure fuel passes. Therefore, by making the seat portion 43 tapered, it is possible to reliably prevent fuel leakage between the seat portion 43 and the valve piston 31 when the valve piston 31 is seated on the seat portion 43. That is, in a state where the valve piston 31 is seated on the seat portion 43, the outflow of fuel from the distribution channel 16 to the outside of the common rail 10 can be stopped more reliably.

  The valve piston 31 is accommodated in the concave portion 17 of the distribution bore portion 15 so as to be able to reciprocate. The valve piston 31 includes, for example, a cylindrical sliding portion 32 whose outer peripheral surface slides with the inner peripheral surface of the recess 17. Further, the valve piston 31 includes a convex portion 33 that protrudes from the sliding portion 32 toward the seat portion 43 side. That is, when the valve piston 31 moves in the concave portion 17 toward the seat portion 43, the corner portion 34 formed at the tip of the convex portion 33 is seated at the seat position 44 of the seat portion 43, so that the valve piston 31 is Stop. Further, when the valve piston 31 moves in the recess 17 toward the bottom 18, the valve piston 31 stops when the end of the sliding portion 32 comes into contact with the bottom 18.

  In the present embodiment, the bottom 18 is tapered, but the shape of the bottom 18 is not limited to this shape. For example, the bottom 18 may be formed in a flat shape. Further, the position of the corner portion 34 seated at the seat position 44 of the seat portion 43 is not limited to the tip of the convex portion 33. For example, suppose that the outer peripheral surface of the front-end | tip part of the convex part 33 is comprised with two inclined surfaces from which an inclination angle differs. In this case, a step is formed at the boundary between the two inclined surfaces. The step portion may be configured to be seated at the seat position 44 of the seat portion 43.

  A communication flow path 35 is formed in the valve piston 31. In the recess 17, the communication flow path 35 communicates the space closer to the bottom 18 than the sliding portion 32 and the space closer to the seat 43 than the sliding portion 32. In other words, the communication channel 35 communicates the space on the bottom 18 side of the sliding portion 32 and the space on the opening side of the concave portion 17 with respect to the sliding portion 32 in the concave portion 17. The communication channel 35 is constituted by, for example, a recess 36 and an orifice 37. The recess 36 opens at the end of the sliding portion 32 on the bottom 18 side and extends to the vicinity of the tip of the protrusion 33. The orifice 37 communicates the outer peripheral side space of the convex portion 33 and the concave portion 36.

  The spring 50 presses the valve piston 31 in a direction away from the seat portion 43. The spring 50 is disposed between the sliding portion 32 of the valve piston 31 and the first surface 41 of the seat block 40 in a state of being shortened from the natural length.

  Next, the operation of the common rail assembly 1 according to the present embodiment incorporated in the common rail injection system will be described. In the following, in the common rail injection system 100 shown in FIG. 9, the operation of the common rail assembly 1 is described by taking as an example the case where the common rail assembly 1 according to the present embodiment is used instead of the conventional common rail assembly 201. explain.

3 and 4 are sectional views showing the periphery of the flow limiter of the common rail assembly according to the embodiment of the present invention, and are diagrams for explaining the operation of the common rail assembly.
The high-pressure fuel supplied from the high-pressure pump 102 to the internal space 12 of the common rail main body 11 flows into the space closer to the seat portion 43 than the sliding portion 32 in the recess 17 through the distribution channel 16 and the communication channel 35. To do. Hereinafter, the space closer to the sheet portion 43 than the sliding portion 32 in the recess 17 is referred to as an outlet-side space 17 a of the recess 17.

  In a state where fuel is not injected from the injector 105, the outlet-side space 17a of the recess 17 is filled with high-pressure fuel and has a pressure equivalent to that of the space upstream of the outlet-side space 17a in the fuel flow direction. It becomes. In other words, the outlet-side space 17 a of the recess 17 has a pressure equivalent to that of the high-pressure fuel existing in the internal space 12, the distribution channel 16, and the communication channel 35. For this reason, as shown in FIG. 2, the valve piston 31 is pressed by the spring 50 and comes into contact with the bottom 18 of the recess 17.

  When fuel is injected from the injector 105, the high-pressure fuel in the supply pipe 104 connected to the injector 105 flows out toward the injector 105. Since the supply pipe 104 communicates with the outlet side space 17 a of the recess 17, the high-pressure fuel existing in the outlet side space 17 a of the recess 17 also flows out to the supply pipe 104 through the outlet channel 45. When the high pressure fuel flows out from the outlet side space 17 a of the recess 17, the pressure of the outlet side space 17 a becomes lower than the pressure of the internal space 12 of the common rail body 11. For this reason, the high-pressure fuel supplied from the high-pressure pump 102 to the internal space 12 of the common rail main body 11 flows into the outlet-side space 17 a of the recess 17 through the distribution channel 16 and the communication channel 35.

  Here, the orifice 37 of the communication flow path 35 is set so that the flow rate of the fuel flowing out from the outlet side space 17a is larger than the flow rate of the fuel flowing into the outlet side space 17a of the recess 17. . For this reason, while the fuel is being injected from the injector 105, the pressure in the outlet side space 17a of the concave portion 17 gradually decreases. Therefore, a pressure difference is generated between the outlet side space 17a of the concave portion 17 and the space (the concave portion 36 or the like) on the upstream side in the fuel flow direction from the outlet side space 17a. A force corresponding to this pressure difference acts on the valve piston 31. Therefore, as shown in FIG. 3, while the fuel is being injected from the injector 105, the valve piston 31 reaches a position where the force acting on the valve piston 31 according to the pressure difference balances with the pressing force of the spring 50. Move to the seat portion 43 side. Hereinafter, the pressure difference between the outlet side space 17a of the recess 17 and the space (the recess 36 or the like) on the upstream side in the fuel flow direction from the outlet side space 17a is referred to as a pressure difference B.

  When the fuel injection from the injector 105 is finished, the outflow of fuel from the outlet side space 17a of the recess 17 is also finished. For this reason, when the high-pressure fuel in the internal space 12 of the common rail body 11 flows into the outlet-side space 17a of the recess 17, the pressure difference B decreases. As the pressure difference B decreases, the valve piston 31 is pushed toward the bottom 18 of the recess 17 by the spring 50. Finally, as shown in FIG. 2, the valve piston 31 stops in contact with the bottom 18 of the recess 17.

  When the supply pipe 104 is damaged, the flow rate of the fuel flowing out from the outlet side space 17a of the recess 17 becomes larger than that during the fuel injection of the injector 105. For this reason, when the supply pipe 104 is damaged, the pressure difference B becomes larger than that during the fuel injection of the injector 105. Therefore, as shown in FIG. 4, the valve piston 31 moves to the moving end on the seat portion 43 side, and the corner portion 34 of the convex portion 33 of the valve piston 31 is seated at the seat position 44 of the seat portion 43. As a result, the outlet channel 45 is closed, and fuel does not flow out of the flow limiter 30. That is, the outflow of fuel from the distribution flow path 16 of the distribution bore portion 15 to the outside of the common rail 10 is stopped. In other words, the flow limiter 30 is closed. Then, the pressing force of the spring 50 applied to the valve piston 31 in the valve closing state shown in FIG. 4 becomes the valve closing load.

  Then, the assembly method of the common rail assembly 1 which concerns on this Embodiment is demonstrated. In the following, a method for adjusting the valve closing load among the assembly methods of the common rail assembly 1 will be described.

  As described above, the flow limiter 30 is designed so as not to block the outlet channel 45 when the injector 105 injects fuel. When the flow rate of the fuel flowing out from the outlet side space 17a of the recess 17 becomes a specified flow rate Q larger than that during the fuel injection of the injector 105, such as when the supply pipe 104 is damaged, the flow limiter 30 45 is designed to be occluded. In other words, when the flow rate of the fuel flowing out from the distribution flow path 16 of the distribution bore portion 15 to the outside of the common rail 10 becomes equal to or higher than the specified flow rate Q, the valve is closed and the outflow of fuel to the outside of the common rail 10 is stopped. Thus, the flow limiter 30 is designed. Here, as described above, the position of the valve piston 31 is determined by the force acting on the valve piston 31 according to the pressure difference B and the pressing force of the spring 50. That is, when the force acting on the valve piston 31 according to the pressure difference B becomes equal to or greater than the valve closing load of the spring 50, the flow limiter 30 is closed. Accordingly, the flow limiter 30 is designed so that the load at the time of closing of the spring 50 becomes a specified load.

  However, in the flow limiter 30 that is actually manufactured, the valve-closing load of the spring 50 may be different from the design-specified load. When the flow limiter 30 is closed due to a processing error of the valve piston 31 and the seat block 40, the sliding portion 32 of the valve piston 31 provided with the spring 50 and the first surface 41 of the seat block 40 are arranged. This is because the distance between them may be different from the design dimension. For this reason, in the flow limiter 30 actually manufactured, the flow limiter 30 is closed when the flow rate of the fuel flowing out from the outlet side space 17a of the recess 17 is smaller than the specified flow rate Q, and the outlet flow path 45 May be blocked. Further, for example, there is a case where the flow limiter 30 is not closed and the outlet channel 45 is not closed even though the flow rate of the fuel flowing out from the outlet side space 17a of the recess 17 is equal to or higher than the specified flow rate Q. is there.

  Here, in the conventional flow limiter 230, the flow rate of the fuel when closing the outlet flow path 245 due to the valve closing state cannot be adjusted. For example, when the flow rate of the fuel when closing the outlet channel 245 is larger than the specified flow rate Q, it is necessary to reduce the load when the spring 250 is closed. In this case, it is necessary to adjust the distance between the bottom of the recess 246 and the sliding portion 232 of the valve piston 231 when the flow limiter 230 is closed. That is, it is necessary to increase the axial length of the spring 250 (the vertical length in FIG. 13) when the flow limiter 230 is closed. However, as can be seen from FIG. 13, in the conventional flow limiter 230, the distance between the bottom of the recess 246 and the sliding portion 232 of the valve piston 231 is determined only by the dimensional accuracy of the valve housing 240 and the valve piston 231. . That is, in the conventional flow limiter 230, there is no place where the distance between the bottom of the recess 246 and the sliding portion 232 of the valve piston 231 can be adjusted by assembly. Therefore, in the conventional flow limiter 230, the flow rate of fuel when closing the outlet channel 245 could not be adjusted.

  On the other hand, the flow limiter 30 according to the present embodiment can adjust the flow rate of the fuel when closing the outlet channel 45 as follows.

  FIG. 5 is a cross-sectional view of the seat block for explaining a method for adjusting the flow rate of the fuel when closing the outlet channel in the flow limiter according to the embodiment of the present invention. Note that the distance L shown in FIG. 5 is the distance between the seat position 44 of the seat portion 43 (where the valve piston 31 is seated) and the first surface 41 in the direction orthogonal to the first surface 41 of the seat block 40. It is.

  In the flow limiter 30 according to the present embodiment, when adjusting the flow rate of fuel when closing the outlet channel 45, as shown in FIG. 5, the distance L between the first surface 41 and the seat position 44 is shown. A plurality of sheet blocks 40 having different values are prepared. By installing one of these seat blocks 40 in the recess 17, the flow rate of fuel when closing the outlet channel 45 can be adjusted.

  For example, when the seat block 40 shown in FIG. 5A is attached to the recess 17, the flow limiter 30 is closed when the flow rate of the fuel flowing out from the outlet side space 17 a of the recess 17 is smaller than the specified flow rate Q. Thus, it is assumed that the outlet channel 45 is closed. In this case, the seat block 40 shown in FIG. 5A is replaced with a seat block 40 shown in FIG. 5C having a distance L larger than the seat block. As a result, the distance between the sliding portion 32 of the valve piston 31 and the first surface 41 of the seat block 40 when the flow limiter 30 is closed by the amount that the seat position 44 is away from the valve piston 31. Can be reduced. That is, the axial length of the spring 50 (the vertical length in FIG. 4) when the flow limiter 30 is closed can be shortened. Thereby, the load at the time of valve closing of the spring 50 can be enlarged. Therefore, by replacing the seat block 40 shown in FIG. 5 (a) with the seat block 40 shown in FIG. 5 (c), the flow rate of the fuel flowing out from the outlet side space 17a of the concave portion 17 becomes a substantially prescribed flow rate Q. Thus, the outlet channel 45 can be closed.

  Further, for example, when the seat block 40 shown in FIG. 5A is attached to the recess 17, the flow limiter is used even though the flow rate of the fuel flowing out from the outlet side space 17 a of the recess 17 is equal to or higher than the specified flow rate Q. It is assumed that 30 is not closed and the outlet channel 45 is not blocked. In this case, the seat block 40 shown in FIG. 5A is replaced with the seat block 40 shown in FIG. 5B having a smaller distance L than the seat block. As a result, the distance between the sliding portion 32 of the valve piston 31 and the first surface 41 of the seat block 40 when the flow limiter 30 is closed by the amount that the seat position 44 approaches the valve piston 31. Can be increased. That is, the axial length of the spring 50 (the vertical length in FIG. 4) when the flow limiter 30 is closed can be increased. Thereby, the load at the time of valve closing of the spring 50 can be made small. Therefore, by replacing the seat block 40 shown in FIG. 5 (a) with the seat block 40 shown in FIG. 5 (b), the flow rate of the fuel flowing out from the outlet-side space 17a of the recess 17 becomes substantially the specified flow rate Q. Thus, the outlet channel 45 can be closed.

  Here, in the common rail assembly 1 in which the fuel flow rate is adjusted when the outlet flow path 45 is closed as described above, when the seat blocks 40 of the two flow limiters 30 are compared, the first surface 41 And the sheet position 44 may have different distances L.

  The fuel flow rate when closing the outlet channel 45 may be adjusted after the common rail assembly 1 is shipped. In this case, a plurality of seat blocks 40 having different distances L between the first surface 41 and the seat position 44 may be prepared, and these seat blocks 40 may be shipped together with the common rail assembly 1. In this case, the common rail assembly 1 to be shipped has a plurality of seat blocks 40 with different distances L between the first surface 41 and the seat position 44 with respect to one flow limiter 30. By configuring the common rail assembly 1 in this way, a purchaser of the common rail assembly 1 can adjust the flow rate of fuel when closing the outlet passage 45 after the purchase of the common rail assembly 1.

  As described above, the common rail assembly 1 according to the present embodiment includes the common rail body 11 and the common rail 10 having the plurality of distribution bore portions 15 and the flow limiter 30 attached to each of the distribution bore portions 15. It is a solid. The flow limiter 30 causes the fuel to flow out of the distribution channel 16 to the outside of the common rail 10 when the flow rate of the fuel flowing out of the distribution channel 16 of the distribution bore portion 15 exceeds the specified flow rate. Stop. In the distribution bore portion 15 of the common rail 10 of the common rail assembly 1 according to the present embodiment, a concave portion 17 in which the bottom portion 18 communicates with the distribution flow path 16 is formed. The flow limiter 30 of the common rail assembly 1 according to the present embodiment includes a valve piston 31, a seat block 40, and a spring 50. The valve piston 31 is accommodated in the recess 17 so as to be reciprocally movable, and has a sliding portion 32 whose outer peripheral surface slides with the inner peripheral surface of the recess 17. The valve piston 31 is provided with a communication channel 35 in the recess 17 that connects the space closer to the bottom 18 than the sliding portion 32 and the space closer to the opening of the recess 17 than the sliding portion 32. Yes. The seat block 40 is attached to a position where the valve piston 31 in the recess 17 is also on the opening side. The seat block 40 has a seat portion 43 on which the valve piston 31 is seated. Further, the seat block 40 has an outlet penetrating from the first surface 41 side, which is the surface facing the valve piston 31, to the second surface 42 side, which is the opposite surface of the first surface 41. A flow path 45 is formed. The spring 50 presses the valve piston 31 in a direction away from the seat block 40. The common rail assembly 1 according to the present embodiment closes the outlet flow path 45 when the valve piston 31 is seated on the seat portion 43, and allows fuel to flow out of the common rail 10 from the distribution flow path 16. Stop.

  As described above, in the common rail assembly 1 according to the present embodiment, the distribution bore portion 15 of the common rail 10 has a partial function of the valve housing 240 of the conventional flow limiter 230, and the concave portion 17 of the distribution bore portion 15 is provided. The flow limiter 30 is accommodated. For this reason, the common rail assembly 1 according to the present embodiment can be reduced in size because the flow limiter 30 does not protrude from the common rail 10. Therefore, the common rail assembly 1 according to the present embodiment can improve the degree of freedom in engine layout.

  Further, the common rail assembly 1 according to the present embodiment can reduce the number of parts as compared with the conventional common rail assembly 201. For this reason, the common rail assembly 1 which concerns on this Embodiment can also reduce manufacturing cost compared with the conventional common rail assembly 201. FIG.

  The vibration of the engine is transmitted to the flow limiter of the common rail assembly via the injector 105 and the supply pipe 104 (see FIG. 9). At this time, in the conventional common rail assembly 201, most of the flow limiter 230 protrudes from the common rail 210, so that the moment acting on the flow limiter 230 increases. For this reason, the conventional common rail assembly 201 has problems such as damage to the flow limiter 230 due to this moment and fuel leakage from the connection point between the flow limiter 230 and the distribution bore portion 215. On the other hand, in the common rail assembly 1 according to the present embodiment, the flow limiter 30 does not protrude from the common rail 10. For this reason, even if the vibration of the engine is transmitted to the common rail assembly 1, problems such as breakage of the flow limiter 30 and fuel leakage from the connection point between the flow limiter 30 and the distribution bore portion 15 can be solved.

  Further, the conventional common rail assembly 201 includes a connection portion between the valve housing 240 of the flow limiter 230 and the distribution bore portion 215 of the common rail 210, a space between the recess 246 of the valve housing 240 and the bush 260, and a recess 246 of the valve housing 240. And the sliding portion 232 of the valve piston 231 may cause a fuel leak. On the other hand, in the common rail assembly 1 according to the present embodiment, there is a possibility of fuel leakage between the concave portion 17 of the distribution bore portion 15 and the sliding portion 32 of the valve piston 31, and the concave portion of the distribution bore portion 15. 17 and the seat block 40. That is, the common rail assembly 1 according to the present embodiment can reduce locations where fuel leakage may occur as compared with the conventional common rail assembly 201. Therefore, the common rail assembly 1 according to the present embodiment can improve safety as compared with the conventional common rail assembly 201.

  In addition, the common rail assembly 1 which concerns on this Embodiment is not limited to the above-mentioned structure. For example, the seat block 40 may be attached to the recess 17 of the distribution bore portion 15 of the common rail 10 as follows.

FIG. 6 is an enlarged view of a main part showing the periphery of the flow limiter of another example of the common rail assembly according to the embodiment of the present invention in cross section.
In the common rail assembly 1 shown in FIG. 6, a stepped portion 20 that contacts the first surface 41 of the seat block 40 is formed in the recess 17 of the distribution bore portion 15 of the common rail 10. In the common rail assembly 1 configured as described above, the seat block 40 can be fixed at a certain position in the recess 17 by bringing the first surface 41 of the seat block 40 into contact with the stepped portion 20. That is, in the common rail assembly 1 configured as described above, the seat block 40 can be fixed at a certain position in the recess 17 without using a jig for positioning the seat block 40. Therefore, by configuring the common rail assembly 1 in this manner, the seat block 40 can be easily positioned in the recess 17.

FIG. 7 is an enlarged view of a main part showing, in cross section, the periphery of a flow limiter as another example of the common rail assembly according to the embodiment of the present invention.
In the common rail assembly 1 shown in FIG. 7, a female screw 21 is formed on the inner peripheral portion of the concave portion 17 of the distribution bore portion 15 over a certain range from the opening portion of the concave portion 17. A male screw 46 is formed on the outer periphery of the seat block 40. Then, the seat block 40 is attached to the recess 17 by screwing the male screw 46 of the seat block 40 into the female screw 21 of the recess 17. The common rail assembly 1 configured as described above can easily attach the seat block 40 to the recess 17. Therefore, the common rail assembly 1 configured as described above can easily replace the seat block 40 and can easily adjust the flow rate of the fuel when the outlet passage 45 is closed. Note that the positioning of the seat block 40 in the concave portion 17 may be performed using a jig (not shown) or may be performed using the step portion 20 shown in FIG.

FIG. 8 is an enlarged view of a main part showing the periphery of a flow limiter as another example of the common rail assembly according to the embodiment of the present invention in cross section.
As shown in FIG. 8, the supply pipe 104 is connected to the distribution bore portion 15 of the common rail 10 by screwing the female screw 62 of the nut 60 into the male screw 19 of the distribution bore portion 15. The common rail assembly 1 shown in FIG. 8 uses the nut 60 to attach the seat block 40 to the recess 17.

  Specifically, a convex portion 61 that protrudes toward the inner peripheral side is formed on the inner peripheral portion of the nut 60. In addition, a flange 104 a that protrudes toward the outer periphery is formed on the outer periphery of the supply pipe 104. Further, the end portion of the supply pipe 104 is in contact with the end portion of the seat block 40. A flange 47 that contacts the tip of the distribution bore 15 is formed on the outer periphery of the seat block 40. For this reason, by screwing the female screw 62 of the nut 60 into the male screw 19 of the distribution bore portion 15, the convex portion 61 of the nut 60 presses the flange portion 104a of the supply pipe 104 toward the seat block 40 side. As a result, the supply pipe 104 presses the seat block 40 toward the distribution bore portion 15. Since the seat block 40 is formed with a flange 47 that contacts the distal end of the distribution bore 15, the seat block 40 is sandwiched between the nut 60 and the distribution bore 15 via the supply pipe 104. Fixed to the recess 17.

  Even when the common rail assembly 1 is configured as shown in FIG. 8, the seat block 40 can be attached to the concave portion 17 using a screw mechanism, as in the common rail assembly 1 shown in FIG. 7. For this reason, even if it comprises the common rail assembly 1 like FIG. 8, the attachment of the seat block 40 to the recessed part 17 becomes easy. Therefore, even if the common rail assembly 1 is configured as shown in FIG. 8, the seat block 40 can be easily replaced, and the fuel flow rate can be easily adjusted when the outlet passage 45 is closed. Note that the seat block 40 may be sandwiched between the nut 60 and the distribution bore portion 15 by forming the step portion 20 shown in FIG. In this case, the collar portion 47 is not necessary for the seat block 40. Further, the seat block 40 may be sandwiched directly between the nut 60 and the distribution bore portion 15 without using the supply pipe 104.

DESCRIPTION OF SYMBOLS 1 Common rail assembly, 10 Common rail, 11 Common rail main body, 12 Internal space, 13 Inlet port, 15 Distribution bore part, 16 Distribution flow path, 17 Recessed part, 17a Outlet side space, 18 Bottom part, 19 Male thread, 20 Step part, 21 Female thread, 30 Flow limiter, 31 Valve piston, 32 Sliding part, 33 Convex part, 34 Corner part, 35 Communication flow path, 36 Concave part, 37 Orifice, 40 Seat block, 41 First surface, 42 Second surface, 43 Seat part, 44 Seat position, 45 Outlet flow path, 46 Male thread, 47 collar part, 50 Spring, 60 nut, 61 Convex part, 62 female thread, 100 Common rail injection system, 101 Fuel tank, 102 High pressure pump, 103 Piping, 104 supply piping, 104a collar, 105 injector, 106 return piping, 201 common rail assembly, 210 Common rail, 211 Common rail body, 212 Internal space, 213 Suction port, 215 Distribution bore part, 216 Distribution flow path, 217 Female thread, 230 Flow limiter, 231 Valve piston, 232 Sliding part, 233 Convex part, 235 Communication flow path, 236 recessed portion, 237 orifice, 240 valve housing, 241 first end portion, 242 second end portion, 243 seat portion, 245 outlet passage, 246 recessed portion, 246a outlet side space, 247 male screw, 248 male screw, 250 spring, 260 Bush, 261 Inlet channel.

Claims (6)

A common rail body having an internal space in which fuel is stored, and a common rail having a plurality of distribution bore portions provided on an outer peripheral portion of the common rail body and having a distribution flow path communicating with the internal space;
When the flow rate of fuel that is attached to each of the distribution bore portions and flows out of the common rail from the distribution channel exceeds a specified flow rate, the fuel flows out of the common rail from the distribution channel. A flow limiter to stop,
A common rail assembly comprising:
The distribution bore portion of the common rail is formed with a recess whose bottom communicates with the distribution flow path.
The flow limiter is
The reciprocating portion is housed in the recess so that the outer peripheral surface slides with the inner peripheral surface of the recess, and the space on the bottom side of the slide and the sliding portion in the recess A valve piston in which a communication flow path communicating with the space on the opening side of the recess is formed,
The recessed portion has a seat portion that is attached to the opening piston side of the valve piston and on which the valve piston is seated, and the first surface side that is the surface facing the valve piston. A seat block in which an outlet channel that penetrates the second surface, which is the surface opposite to the first surface, is formed;
A spring provided between the sliding portion and the seat block and pressing the valve piston in a direction away from the seat block;
With
A common rail assembly configured such that when the valve piston is seated on the seat portion, the outlet flow path is closed, and the outflow of fuel from the distribution flow path to the outside of the common rail is stopped.   The common rail assembly according to claim 1, wherein the seat block is press-fitted into the recess.   The common rail assembly according to claim 1, wherein the seat portion has a tapered shape with a diameter that decreases from the first surface side toward the second surface side. When comparing the sheet blocks of two flow limiters,
The common rail set according to any one of claims 1 to 3, wherein a distance between a portion of the seat portion where the valve piston is seated and the first surface is different in a direction orthogonal to the first surface. Solid. A plurality of the sheet blocks for one flow limiter;
Each of the plurality of seat blocks is different in the direction orthogonal to the first surface, and the distance between the seat surface where the valve piston is seated and the first surface is different,
The common rail assembly according to any one of claims 1 to 4, wherein one of the plurality of seat blocks is configured to be attached to the recess. A method for assembling the common rail assembly according to any one of claims 1 to 5,
Preparing a plurality of the seat blocks in which a distance between a position where the valve piston is seated in the seat portion and the first surface is different in a direction orthogonal to the first surface;
One of the plurality of seat blocks is attached to the recess, and a common rail assembly that adjusts the pressing force of the spring applied to the valve piston in a state where the valve piston is seated on the seat portion. Assembly method.

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