JP5672212B2 - Flow damper - Google Patents

Description

  The present invention relates to a flow damper that closes a fuel passage when the flow rate of fuel flowing through an injector abnormally increases.

  A conventional flow damper has a valve body having a sliding hole that constitutes a fuel passage and a valve seat that is positioned downstream of the sliding hole, and a throttle passage and a valve seat that constitute the fuel passage, thereby allowing the fuel passage to be disposed. A piston having a valve portion for shutting off and a spring for biasing the piston in the valve opening direction are provided, and the piston is lifted toward the valve seat side against the spring by the fluid force due to the differential pressure of the fuel before and after the throttle passage. It is like that.

  And if an abnormality such as excessive fuel outflow occurs in the injector and the flow rate of the fuel flowing from the common rail to the injector through the flow damper exceeds the set flow rate, the fluid force increases and the piston lift increases. The piston is seated on the valve seat, and the fuel passage from the common rail to the injector is closed (see, for example, Patent Document 1).

Japanese Patent No. 4100703

  However, since the operating condition when the flow damper closes the fuel passage (hereinafter referred to as the valve closing operating condition) differs depending on the specifications of the internal combustion engine (hereinafter referred to as the engine), a plurality of flow dampers having different valve closing operating conditions. Was necessary.

  In view of the above points, an object of the present invention is to enable a single type of flow damper to support a plurality of engines having different specifications.

In order to achieve the above object, according to the first aspect of the present invention, the flow damper (20) closes the fuel passage to the injector (2) when the flow rate of the fuel flowing to the injector (2) abnormally increases. , sliding the valve body (200), into the sliding hole (2002) having a valve seat located downstream of the slide hole constituting the fuel passageway (2002) and the slide hole (2002) and (2003) A piston (210) having a valve part (2123) that is freely arranged and shuts off the fuel passage by being seated on the valve seat (2003), and a throttle passage (2124) that constitutes the fuel passage, and a sliding hole (2002) And a spring (220) that urges the piston (210) in the valve opening direction, and the piston (210) slides in the sliding hole (2002). A), and a second piston member (212) having a valve portion (2123), the first piston member and (211) the second piston member (212), the outer peripheral portion of the second piston member (212) first With the inner peripheral portion of the one piston member (211) supported , the relative position in the piston sliding direction is screwed so that adjustment is possible , and the piston sliding between the first piston member (211) and the second piston member (212) The distance (L) between the valve seat (2003) and the valve portion (2123) varies depending on the relative position in the direction.

  According to this, since the valve closing operation condition can be changed by changing the distance (L) between the valve seat (2003) and the valve portion (2123), a plurality of specifications having different specifications can be obtained with one type of flow damper. Can correspond to the engine.

In the invention described in claim 2, when the flow rate of the fuel flowing through the injector (2) is increased abnormally, an injector flow closes the fuel passage leading to (2) the damper (20), constitutes a fuel passage A valve body (200) having a sliding hole (2002) and a valve seat (2003) located on the downstream side of the sliding hole (2002), and slidably disposed in the sliding hole (2002). A piston (210) having a valve portion (2123) for blocking the fuel passage by being seated on (2003) and a throttle passage (2124) constituting the fuel passage; and a piston (210) disposed in the sliding hole (2002), 210) and a spring (220) for urging the valve in the valve opening direction. The piston (210) includes a first piston member (211) that slides in the sliding hole (2002), and a throttle passage (212). ) Having a second piston member (212), and the first piston member (211) and the second piston member (212) are screwed together so that the relative position in the piston sliding direction can be adjusted, and the throttle passage (2124). ) Can be closed by the first piston member (211), and depending on the relative position of the first piston member (211) and the second piston member (212) in the piston sliding direction, A feature is that the area of the downstream end of the throttle passage (2124) closed by the first piston member (211) is changed.

  According to this, since the valve closing operation condition can be changed by changing the opening area of the downstream side end portion in the throttle passage (2124), one type of flow damper corresponds to a plurality of engines having different specifications. be able to.

  According to a third aspect of the present invention, in the flow damper according to the first or second aspect, the piston (210) is a lock nut (1) that prevents the first piston member (211) and the second piston member (212) from loosening. 213). According to this, it is possible to prevent a change in the valve closing operation condition during use.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a lineblock diagram showing a fuel injection device provided with a flow damper concerning a 1st embodiment of the present invention. It is sectional drawing of the flow damper of FIG. It is sectional drawing of the flow damper which concerns on 2nd Embodiment of this invention. It is an A arrow directional view of the principal part in the piston of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a configuration diagram illustrating a fuel injection device including a flow damper according to the first embodiment, and FIG. 2 is a cross-sectional view of the flow damper of FIG.

  As shown in FIG. 1, the fuel injection device is a system that injects fuel into each cylinder of an engine (for example, a diesel engine: not shown), and includes a common rail 1, an injector 2, a supply pump 3, an ECU 4 (engine control unit), It consists of EDU5 (drive unit) and the like.

  The common rail 1 is a pressure accumulation container that accumulates high pressure fuel supplied to the injector 2 in a pressure accumulation chamber, and a supply pump 3 that pumps high pressure fuel through a high pressure pump pipe 6 so that a common rail pressure corresponding to the fuel injection pressure is accumulated. And a plurality of injector pipes 7 for supplying high-pressure fuel to each injector 2. In addition, the flow damper 20 is provided in the connection part of the common rail 1 and the injector piping 7, and the detail of the flow damper 20 is mentioned later.

  A pressure limiter 10 is attached to a relief pipe 9 that returns fuel from the common rail 1 to the fuel tank 8. The pressure limiter 10 is a pressure safety valve, and is opened when the common rail pressure exceeds the limit set pressure, and suppresses the common rail pressure below the limit set pressure. A pressure reducing valve 11 is attached to the common rail 1. The pressure reducing valve 11 is opened by a valve opening instruction signal given from the ECU 4 and rapidly reduces the common rail pressure via the relief pipe 9. Thus, by mounting the pressure reducing valve 11 on the common rail 1, the ECU 4 can quickly control the common rail pressure to a pressure corresponding to the vehicle running state. There are some models in which the pressure reducing valve 11 is not provided.

  The injector 2 is mounted in each cylinder of the engine and supplies fuel into each cylinder. The injector 2 is connected to the downstream ends of a plurality of injector pipes 7 branched from the common rail 1 and accumulated in the common rail 1. A fuel injection nozzle that injects high-pressure fuel into each cylinder and an electromagnetic valve that performs lift control of a needle accommodated in the fuel injection nozzle are mounted. The leaked fuel from the injector 2 is also returned to the fuel tank 8 through the relief pipe 9.

  The supply pump 3 is a high-pressure fuel pump that pumps high-pressure fuel to the common rail 1, and is equipped with a feed pump that sucks fuel in the fuel tank 8 into the supply pump 3 through the filter 12, and is sucked up by this feed pump. The fuel is compressed to a high pressure and pumped to the common rail 1. The feed pump and the supply pump 3 are driven by a common cam shaft 13. The camshaft 13 is rotationally driven by the engine.

  The supply pump 3 is equipped with an SCV 14 (suction metering valve) for adjusting the degree of opening of the fuel flow path in the fuel flow path that guides the fuel into the pressurizing chamber that pressurizes the fuel to a high pressure. The SCV 14 is a valve that adjusts the amount of fuel sucked into the pressurizing chamber and changes the discharge amount of fuel pumped to the common rail 1 by being controlled by a pump drive signal from the ECU 4. The common rail pressure is adjusted by adjusting the discharge amount of fuel to be pumped to the vehicle. That is, the ECU 4 controls the SCV 14 to control the common rail pressure to a pressure corresponding to the vehicle running state.

  The ECU 4 includes functions of a CPU that performs control processing and arithmetic processing, a storage device (ROM, standby RAM or EEPROM, memory such as RAM) that stores various programs and data, an input circuit, an output circuit, a power supply circuit, and the like. A microcomputer having a known structure is provided. Various arithmetic processes are performed on the basis of sensors signals (engine parameters: signals corresponding to occupant operating conditions, engine operating conditions, etc.) read into the ECU 4. In addition to the rail pressure sensor 15 that detects the common rail pressure, the ECU 4 includes an accelerator sensor that detects the accelerator opening degree, an engine speed sensor that detects the engine speed, and engine cooling as means for detecting the operating state and the like. Sensors such as a water temperature sensor for detecting the water temperature are connected.

  An example of a specific calculation in the ECU 4 will be described. The ECU 4 performs control of an injector control system that performs drive control of the injector 2 and a rail pressure control system that performs drive control of the SCV 14. For each fuel injection, the injector control system calculates the injection mode, the target injection amount, and the injection start timing based on the program stored in the ROM and the sensor signals (engine parameters) read in the RAM. The injector valve opening signal is calculated. The rail pressure control system calculates the target rail pressure based on the program stored in the ROM and the sensor signals (engine parameters) read in the RAM, and calculates the actual rail pressure calculated from the rail pressure sensor 15. An SCV drive signal for making the value coincide with the target rail pressure is calculated.

  The EDU 5 has an injector drive circuit for supplying a valve opening drive current to the solenoid valve of the injector 2 based on an injector valve open signal given from the ECU 4, and a drive current value to the SCV 14 based on an SCV drive signal (duty signal) given from the ECU 4. And a pump drive circuit for providing The EDU 5 may be mounted in the same case as the ECU 4.

  The flow damper 20 is provided at a connection portion between the common rail 1 and the injector pipe 7 and has a function of closing a fuel passage from the common rail 1 to the injector 2 when the flow rate of fuel flowing from the common rail 1 to the injector 2 increases abnormally. It is.

  As shown in FIG. 2, the flow damper 20 includes a substantially cylindrical valve body 200 fastened to the common rail 1 (see FIG. 1), a piston 210 reciprocating inside the valve body 200, and the piston 210. A spring 220 that biases the valve in the valve opening direction and a stopper 230 that restricts the movement range of the piston 210 in the valve opening direction are provided.

  The valve body 200 is made of an iron-based metal, and a screw 2000 that is screwed to the common rail 1 is formed on one end side of the outer peripheral portion thereof, and an injector pipe 7 (see FIG. 1) on the other end side of the outer peripheral portion. A screw 2001 to be screwed is formed.

  Inside the valve body 200, a sliding hole 2002 is formed as a fuel passage for slidably holding the piston 210. Further, inside the valve body 200, a tapered valve seat 2003 is formed on the downstream side of the fuel flow of the sliding hole 2002, and the piston 210 contacts and separates. A fuel passage is formed on the downstream side of the fuel flow of the valve seat 2003. A body fuel passage 2004 is formed.

  The piston 210 is a substantially cylindrical first piston member 211 that is slidably held in the sliding hole 2002, and a bottomed cylindrical shape that is screwed to the first piston member 211 and that contacts and separates from the valve seat 2003. The second piston member 212, the first piston member 211, and a lock nut 213 that prevents screw loosening of the second piston member 212 are provided. The first piston member 211, the second piston member 212, and the lock nut 213 are made of an iron-based metal.

  The first piston member 211 has a female screw 2110 formed in a hole penetrating in the axial direction.

  The second piston member 212 has a male screw 2120 formed on one end side of the outer peripheral portion, a groove 2121 formed on one end side end portion, a diameter smaller than that of the first piston member 211, and a fuel flow downstream side of the first piston member 211. By forming a bottomed cylindrical protruding cylinder portion 2122 protruding from the hole of the first piston member 211 toward the end of the first piston member 211, and an end of the protruding cylinder portion 2122 on the downstream side of the fuel flow. A valve portion 2123 for blocking the fuel passage is provided.

  Further, a throttle passage 2124 is formed in the second piston member 212 as a fuel passage that communicates the fuel flow upstream end surface of the second piston member 212 and the outer peripheral surface of the protruding cylindrical portion 2122. The throttle passage 2124 includes a piston fuel passage 2124a extending from the fuel flow upstream end surface of the second piston member 212 to an intermediate portion in the axial direction, and a piston orifice communicating the piston fuel passage 2124a and the outer peripheral surface of the protruding cylindrical portion 2122. 2124b. The piston orifice 2124b has a minimum passage area in the fuel passage in the flow damper 20.

  Then, after the female screw 2110 of the first piston member 211 and the male screw 2120 of the second piston member 212 are screwed together and the relative position of the first piston member 211 and the second piston member 212 in the piston sliding direction is adjusted, the male screw 2120 is adjusted. The piston 210 is formed by screwing the lock nut 213 into the screw 210. At this time, using the jig that engages with the groove 2121 of the second piston member 212 and the jig that engages with the groove 2130 formed at one end of the lock nut 213, The lock nut 213 is tightened.

  The stopper 230 is made of an iron-based metal and is disposed on the fuel flow upstream side of the piston 210. The stopper 230 is inserted into the sliding hole 2002 and is opposed to the upstream end surface of the fuel flow in the piston 210, and the stopper flange portion sandwiched between the common rail 1 and the valve body 200. 2301. Furthermore, a stopper fuel passage 2302 is formed inside the stopper 230 as a fuel passage that communicates the fuel flow upstream end surface of the stopper flange portion 2301 and the fuel flow downstream end surface of the stopper cylinder portion 2300.

  The piston 210 is urged by a spring 220 disposed in the sliding hole 2002 in a direction in which the valve portion 2123 is separated from the valve seat 2003 (that is, in a valve opening direction). When the fuel is not flowing or when the flow rate is very small, the end face on the upstream side of the fuel flow in the piston 210 abuts against the stopper 230 so that the movement range of the piston 210 in the valve opening direction is restricted.

  In the above configuration, the fuel introduced from the common rail 1 to the flow damper 20 passes through the stopper fuel passage 2302, the throttle passage 2124, and the body fuel passage 2004 of the flow damper 20, and is supplied to the injector 2 through the injector pipe 7. .

  Along with the fuel supply to the injector 2, a differential pressure is generated before and after the throttle passage 2124, and the piston 210 is biased toward the valve seat 2003 (ie, in the valve closing direction) by the fluid force due to the differential pressure. The

  When the flow rate of the fuel flowing through the injector 2 is small, such as micro injection, the piston urging force due to the fluid force is smaller than the set load of the spring 220, so that the piston 210 is urged by the spring 220 as shown in FIG. And held at the position in contact with the stopper 230. That is, the valve portion 2123 is in a state away from the valve seat 2003, and the flow damper 20 is in a valve open state.

  When the flow rate of the fuel flowing through the injector 2 such as large injection increases in the normal range, the differential pressure before and after the throttle passage 2124 increases, and the piston biasing force due to the fluid force also increases. When the piston biasing force due to the fluid force becomes larger than the set load of the spring 220, the piston 210 lifts (moves) toward the valve seat 2003 side. In this state, the piston 210 is located at a position where the piston urging force by the fluid force and the spring load of the spring 220 are balanced.

  When the flow rate flowing through the injector 2 increases abnormally due to abnormalities such as excessive fuel outflow in the injector 2 and the differential pressure before and after the throttle passage 2124 exceeds the preset differential pressure, the piston 210 moves to the valve seat 2003. The valve portion 2123 is further seated on the valve seat 2003, and the body fuel passage 2004 is closed. In this way, if some trouble occurs in the flow damper 20 and the flow rate of the fuel flowing from the common rail 1 to the injector 2 increases beyond the set flow rate (that is, the valve closing operation condition), the fuel reaching the injector 2 from the common rail 1 Close the passage to stop the high-pressure fuel from flowing out.

  Here, the larger the distance L in the piston sliding direction between the valve portion 2123 and the valve seat 2003 when the piston 210 is in contact with the stopper 230 (hereinafter referred to as piston lift L), the larger the flow damper. 20 becomes difficult to close, and the set flow rate which is the valve closing operation condition of the flow damper 20 becomes large.

  Therefore, by adjusting the relative positions of the first piston member 211 and the second piston member 212 in the piston sliding direction and changing the piston lift L, the valve closing operation condition of the flow damper 20 can be changed. Thereby, it is possible to cope with a plurality of engines having different specifications with one type of flow damper 20.

(Second Embodiment)
A second embodiment of the present invention will be described. FIG. 3 is a cross-sectional view of a flow damper according to the second embodiment, and FIG. 4 is a view of the main part of the piston of FIG. Only the parts different from the first embodiment will be described below.

  As shown in FIGS. 3 and 4, an annular lift adjustment shim 240 is sandwiched between the piston 210 and the stopper 230.

  In the second piston member 212, the groove 2121 (see FIG. 2) is eliminated, and a two-sided width 2125 is formed on the outer peripheral portion instead of the groove 2121. Further, the first piston member 211 includes an annular set load adjustment shim 2126.

  A piston orifice 2124b, which is a downstream end portion of the throttle passage 2124, is an elongated hole that is long in the piston sliding direction. Further, the area of the piston orifice 2124b closed by the first piston member 211, in other words, the opening area of the piston orifice 2124b, according to the relative positions of the first piston member 211 and the second piston member 212 in the piston sliding direction. Is configured to change. The shape of the opening may be a round hole, a triangular hole, a square hole, a notch, a plurality of small holes, or the like.

  The larger the opening area of the piston orifice 2124b, the more difficult it is to close the flow damper 20, and the set flow rate that is the valve closing operation condition of the flow damper 20 increases. Therefore, by changing the opening area of the piston orifice 2124b by adjusting the relative positions of the first piston member 211 and the second piston member 212 in the piston sliding direction, the valve closing operation condition of the flow damper 20 is changed. Can do. Thereby, it is possible to cope with a plurality of engines having different specifications with one type of flow damper 20.

  Here, since the piston lift L changes with the adjustment of the relative position of the first piston member 211 and the second piston member 212 in the piston sliding direction, the first piston member is selected by selecting the lift adjustment shim 240. Regardless of the relative position of 211 and the second piston member 212 in the piston sliding direction, the piston lift L is adjusted to a predetermined value.

  Further, since the set load of the spring 220 changes depending on the thickness of the selected lift adjustment shim 240, the set load of the spring 220 is kept constant regardless of the thickness of the lift adjustment shim 240 by selecting the set load adjustment shim 2126. Adjust to the value.

  In addition, each said embodiment can be arbitrarily combined in the range which can be implemented.

2 Injector 20 Flow damper 200 Valve body 210 Piston 211 1st piston member 212 2nd piston member 220 Spring 2002 Sliding hole 2003 Valve seat 2123 Valve part 2124 Restriction passage

Claims (3)

A flow damper (20) for closing a fuel passage leading to the injector (2) when the flow rate of the fuel flowing to the injector (2) abnormally increases;
The previous SL valve body having a valve seat (2003) located on the downstream side of the fuel passage constituting the sliding hole (2002) and said slide hole (2002) (200),
A valve portion (2123), which is slidably disposed in the sliding hole (2002) and blocks the fuel passage by being seated on the valve seat (2003), and a throttle passage (2124) constituting the fuel passage A piston (210) having:
A spring (220) disposed in the sliding hole (2002) and biasing the piston (210) in the valve opening direction;
The piston (210) includes a first piston member (211) that slides in the sliding hole (2002), and a second piston member (212) having the valve portion (2123),
The first piston member (211) and the second piston member (212) are arranged so that the outer periphery of the second piston member (212) is supported by the inner periphery of the first piston member (211). The relative position in the moving direction is screwed so that it can be adjusted,
The distance (L) between the valve seat (2003) and the valve portion (2123) changes according to the relative position of the first piston member (211) and the second piston member (212) in the piston sliding direction. The flow damper is characterized by being configured as follows. A flow damper (20) for closing a fuel passage leading to the injector (2) when the flow rate of the fuel flowing to the injector (2) abnormally increases;
The previous SL valve body having a valve seat (2003) located on the downstream side of the fuel passage constituting the sliding hole (2002) and said slide hole (2002) (200),
A valve portion (2123), which is slidably disposed in the sliding hole (2002) and blocks the fuel passage by being seated on the valve seat (2003), and a throttle passage (2124) constituting the fuel passage A piston (210) having:
A spring (220) disposed in the sliding hole (2002) and biasing the piston (210) in the valve opening direction;
The piston (210) includes a first piston member (211) that slides in the sliding hole (2002), and a second piston member (212) having the throttle passage (2124),
The first piston member (211) and the second piston member (212) are screwed together so that the relative position in the piston sliding direction can be adjusted,
The downstream end of the throttle passage (2124) can be closed by the first piston member (211),
Downstream of the throttle passage (2124) blocked by the first piston member (211) according to the relative position of the first piston member (211) and the second piston member (212) in the piston sliding direction. A flow damper configured to change an area of a side end portion.   The flow damper according to claim 1 or 2, wherein the piston (210) includes a lock nut (213) that prevents loosening of the first piston member (211) and the second piston member (212). .

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