JP5516355B2 - Injector - Google Patents

Description

  The present invention relates to an injector for injecting and supplying fuel to an engine.

2. Description of the Related Art Conventionally, it is known that an injector 100 that injects and supplies fuel with an extremely high injection pressure has a structure as shown in FIG.
That is, the injector 100 includes an injection nozzle 101 that injects high-pressure fuel, a main body 102 that receives high-pressure fuel from a fuel supply source and guides the high-pressure fuel toward the injection nozzle 101, and an electromagnetic actuator 103 that opens the injection nozzle 101. The injection nozzle 101 is fastened to the front end of the main body 102 in the axial direction, and the electromagnetic actuator 103 is fastened to the rear end of the main body 102 in the axial direction.

  The injection nozzle 101 includes a nozzle needle 105 that moves in the axial direction to open and close the injection hole 104, and a nozzle body 106 that supports and accommodates the nozzle needle 105 slidably in the axial direction. 105 is supported by the nozzle body 106 and urged in the valve closing direction by a spring 107, thereby forming a substantially annular cylindrical nozzle chamber 108 between the nozzle body 106.

  A high pressure passage 109 through which high pressure fuel flows is connected to the nozzle chamber 108, and the high pressure fuel received by the main body 102 from the fuel supply source is guided to the nozzle chamber 108 through the high pressure passage 109. Thereby, the nozzle chamber 108 forms a part of the high-pressure channel 109, and the fuel pressure in the nozzle chamber 108 acts on the nozzle needle 105 in the valve opening direction.

  In addition, a control chamber 110 for operating the axial movement of the nozzle needle 105 is provided at the rear end of the main body 102 in the axial direction, and a high-pressure flow path 109 is connected to the control chamber 110 to guide high-pressure fuel. . The fuel pressure in the control chamber 110 acts on the nozzle needle 105 in the valve closing direction via the command piston 111. Further, the control chamber 110 is opened and closed with respect to the low pressure flow path 112 by the electromagnetic actuator 103. When the control chamber 110 is opened with respect to the low pressure flow path 112, the fuel pressure is reduced. Raise.

  Here, the low-pressure channel 112 is a fuel channel through which fuel having a lower pressure than the fuel pressure in the high-pressure channel 109 flows. In the low-pressure channel 112, the fuel in the nozzle chamber 108 leaks through the sliding clearance between the nozzle body 106 and the nozzle needle 105, or the fuel in the control chamber 110 flows into the sliding clearance between the main body 113 and the command piston 111. It leaks through and flows in at a low pressure.

  With the above configuration, when the electromagnetic actuator 103 operates, the fuel pressure in the control chamber 110 decreases and the resultant force acting in the axial direction on the nozzle needle 105 increases in the valve opening direction, so that the nozzle needle 105 moves in the valve opening direction. By moving, the space between the nozzle hole 104 and the nozzle chamber 108 is opened, and fuel injection is started. When the electromagnetic actuator 103 stops operating, the fuel pressure in the control chamber 110 increases and the resultant force acting in the axial direction on the nozzle needle 105 increases in the valve closing direction, so that the nozzle needle 105 moves in the valve closing direction. Thus, the gap between the nozzle hole 104 and the nozzle chamber 108 is closed, and fuel injection stops.

By the way, in the injection nozzle 101 of the injector 100, the following situations are regarded as problems as the injection pressure increases.
That is, in the injection nozzle 101, the nozzle needle 105 is supported by the nozzle body 106 in the axially rear portion 114 so as to be slidable directly in order to limit the number of components to two points, that is, the nozzle needle 105 and the nozzle body 106. The nozzle chamber 108 is formed between the nozzle body 105 and the nozzle body 106 by the axially forward portion 115 of the nozzle needle 105.

  In order to enable high-pressure fuel to be supplied from the high-pressure flow path 109 of the main body 102 to the nozzle chamber 108, the rear portion 116 of the nozzle chamber 108 is provided in a bag shape to expand in the radial direction and to the axial direction. An inclined fuel channel 117 is linearly provided as a part of the high-pressure channel 109 and is connected to the rear part 116 (hereinafter, the rear part 116 is referred to as a bag hole 116 and the fuel channel 117 is a side channel. 117.)

  For this reason, the projection 118 protruding to the flow path side is generated by the connection between the bag hole 116 and the side flow path 117, and it is assumed that stress concentration occurs in the protrusion 118 and the pressure resistance decreases. It is considered that as the injection pressure increases, the problem will become even more problematic.

  The fuel in the nozzle chamber 108 leaks into the low-pressure channel 112 through a sliding clearance formed between the axially rear portion 114 and the nozzle body 106. However, when the injection pressure increases, the sliding clearance is reduced. Since the fuel passing therethrough also has a high pressure, the sliding clearance is expanded. As a result, it is assumed that fuel leaking from the nozzle chamber 108 to the low-pressure flow path 112 will increase, and such a situation will be considered as a problem as the injection pressure increases. It is done.

  Patent Document 1 discloses a technique for relaxing the stress concentration generated in the protrusion by providing the hole so that the apex angle of the protrusion generated by the connection between the bag hole and the side flow path becomes an obtuse angle. . However, the process of providing the bag hole so that the apex angle of the protrusion becomes an obtuse angle is more complicated than the case where the apex angle of the protrusion becomes an acute angle, and the processing cost becomes high. Moreover, even if the apex angle of the protrusion is made obtuse, the stress concentration cannot be completely avoided, and it is considered that the stress concentration in the protrusion will again be regarded as a problem as the injection pressure increases further. It is done.

JP 2006-194173 A

  The present invention has been made in order to solve the above-described problems, and the object of the present invention is a situation (both hole and side flow path) that is likely to become apparent in the injection nozzle of an injector as the injection pressure increases. The pressure resistance of the projections caused by the connection with the nozzle needle and the expansion of the sliding clearance formed on the outer periphery of the nozzle needle are avoided.

[Means of Claim 1]
The injector according to claim 1 includes an injection nozzle that injects high-pressure fuel, and a main body that receives high-pressure fuel from a fuel supply source, and is configured by fastening the injection nozzle to an axial front end side of the main body. .

  The injection nozzle is housed in a nozzle body having an injection hole, and is provided in a cylindrical shape separate from the nozzle needle that moves in the axial direction to open and close the injection hole. And a cylindrical member that is slidably supported in the axial direction and forms a first sliding clearance with the nozzle needle. The nozzle body is provided in a substantially cylindrical shape and has a cylinder that opens to the rear end in the axial direction and communicates with the nozzle hole. The nozzle needle and the cylindrical member are accommodated in the cylinder and are annularly formed between the nozzle body and the nozzle body. The rear end of the nozzle needle protrudes rearward in the axial direction from the cylindrical member.

  The main body forms a control chamber for operating the movement of the nozzle needle in the axial direction, and has a command piston that contacts the rear end of the nozzle needle and transmits the fuel pressure in the control chamber to the nozzle needle. Also, an intermediate member is disposed on the axial front end side of the main body, and both the main body and the intermediate member have a part of the high-pressure channel through which high-pressure fuel flows and fuel having a pressure lower than the fuel pressure in the high-pressure channel. It has a part of the flowing low pressure channel. The main body and the intermediate member are incorporated so that the high-pressure flow paths of each of the main body and the intermediate member communicate with each other, and the low-pressure flow paths of each of the main body and the intermediate member communicate with each other. The path is open at the axial end of the intermediate member.

  The injection nozzle is arranged so that the annular fuel flow path communicates with the high pressure flow path of the intermediate member, and the rear end of the nozzle needle fits into the low pressure flow path of the intermediate member. The annular fuel flow path communicates with the high pressure flow path of the intermediate member to form a part of the high pressure flow path of the injection nozzle, and the tip of the command piston protrudes from the main body toward the front end in the axial direction. The nozzle needle abuts on the rear end portion of the intermediate member in the low pressure flow path of the intermediate member without sliding contact with the nozzle member. Further, the cylindrical member is urged rearward in the axial direction by a predetermined urging means, and comes into liquid-tight contact with the axial end of the intermediate member.

  The rear end portion of the nozzle needle is fitted into the low pressure flow path of the intermediate member, thereby forming a second sliding clearance narrower than the first sliding clearance with the intermediate member. The low-pressure flow path and the low-pressure flow path of the main body are sealed, and the fuel from the high-pressure flow path of the injection nozzle passes through the first sliding clearance and the second sliding clearance in the low-pressure flow path of the intermediate member and the low-pressure flow path of the main body. Flows in at low pressure.

  Thus, the annular fuel flow path corresponding to the conventional nozzle chamber can be formed as a bag hole in the rear portion, or without providing a side flow path in the nozzle body and connected to the bag hole. High-pressure fuel can be supplied to the fuel passage on the injection nozzle side that communicates with the injection hole by communicating with the high-pressure passage on the intermediate member side and the main body side. For this reason, it is possible to increase the injection pressure without considering the pressure-resistance reduction of the protrusions caused by the connection between the bag hole and the side flow path.

In addition, a first sliding clearance is formed between the nozzle needle and the tubular member, and an annular fuel passage through which high-pressure fuel passes is formed on the outer peripheral side of the tubular member. For this reason, even if the fuel passing through the first sliding clearance is increased as the injection pressure is increased, high pressure fuel pressure acts on the cylindrical member from the outer peripheral side, so the first sliding clearance is It will not expand.
As described above, a situation that is likely to become apparent as the injection pressure increases (decrease in pressure resistance of the protrusion caused by the connection between the bag hole and the side flow path, and expansion of the sliding clearance formed on the outer periphery of the nozzle needle) Can be avoided.

  Further, by dividing the sliding clearance into first and second sliding clearances in series with respect to the flow of fuel leaking from the high pressure channel to the low pressure channel, the fuel pressure in the high pressure channel is high for the amount of leakage. Can be reduced by the first sliding clearance, and can be reduced by the second sliding clearance when the fuel pressure in the high-pressure channel is medium to low. For this reason, even if the injection pressure is changed in a wide range from a low intermediate pressure of 20 MPa to 100 MPa as in idling to a high pressure exceeding 150 MPa, the leak amount can be maintained at a small amount.

  That is, when the low-pressure channel is formed on the inner peripheral side of the cylindrical member without slidably supporting the rear end portion of the nozzle needle by the intermediate member, for example, the high-pressure channel (the annular ring on the outer peripheral side of the cylindrical member) The tubular member is deformed to the inner peripheral side by the pressure difference between the fuel pressure in the fuel passage) and the fuel pressure in the low pressure passage on the inner peripheral side of the cylindrical member.

  The amount of deformation toward the inner peripheral side increases as the fuel pressure in the high-pressure channel increases, and the first sliding clearance decreases as the amount of deformation toward the inner peripheral side increases, hindering movement of the nozzle needle in the axial direction. (Hereinafter, a phenomenon in which movement of the nozzle needle in the axial direction is hindered by deformation of a member (for example, a cylindrical member) disposed on the outer peripheral side of the nozzle needle toward the inner peripheral side). , And call it “we hold”.)

  Therefore, assuming that the injection pressure is high and there is a high possibility of “clamping”, the first sliding clearance is set to be large in consideration of the deformation amount of the cylindrical member when the injection pressure is high. . Thereby, even if the injection pressure becomes high and the deformation amount of the cylindrical member increases, the amount of fuel leaking through the first sliding clearance can be suppressed while suppressing the possibility of occurrence of “holding”. Can do.

  If the first sliding clearance is set to be large, the amount of deformation of the cylindrical member is reduced when the injection pressure is medium to low, and the amount of fuel leaking through the first sliding clearance is increased. . Therefore, the second sliding clearance is set to be narrower than the first sliding clearance. As a result, when the injection pressure is an intermediate or low pressure, the second sliding clearance can suppress the fuel that has flowed into the first sliding clearance from leaking into the low-pressure flow path.

  The intermediate member is not structured to receive the fuel pressure so that the portion that slidably supports the nozzle needle is deformed inward on the entire circumference, so even if the injection pressure becomes high, the intermediate member There is a very low possibility that "clogging" will occur.

  Further, the rear end portion of the nozzle needle is slidably supported by an intermediate member disposed on the front end side of the main body to form a second sliding clearance and block the low pressure flow path. Without being slidably supported by the intermediate member, it contacts the rear end of the nozzle needle in the low pressure flow path of the intermediate member. Thereby, the assembling work of the intermediate member can be performed in consideration of only the accuracy of the second sliding clearance without considering the sliding support of the command piston. For this reason, since the shaft misalignment management of the intermediate member can be relaxed, the number of work man-hours related to manufacturing and the like can be reduced.

(A) is the whole block diagram of an injector, (b) is the principal part block diagram of an injector (Example). (A) is a whole block diagram of an injector, (b) is a principal part block diagram of an injector (conventional example).

  The injector of the embodiment includes an injection nozzle that injects high-pressure fuel, and a main body that receives high-pressure fuel from a fuel supply source, and is configured by fastening the injection nozzle to the front end side in the axial direction of the main body.

  The injection nozzle is housed in a nozzle body having an injection hole, and is provided in a cylindrical shape separate from the nozzle needle that moves in the axial direction to open and close the injection hole. And a cylindrical member that is slidably supported in the axial direction and forms a first sliding clearance with the nozzle needle. The nozzle body is provided in a substantially cylindrical shape and has a cylinder that opens to the rear end in the axial direction and communicates with the nozzle hole. The nozzle needle and the cylindrical member are accommodated in the cylinder and are annularly formed between the nozzle body and the nozzle body. The rear end of the nozzle needle protrudes rearward in the axial direction from the cylindrical member.

  The main body forms a control chamber for operating the movement of the nozzle needle in the axial direction, and has a command piston that contacts the rear end of the nozzle needle and transmits the fuel pressure in the control chamber to the nozzle needle. Also, an intermediate member is disposed on the axial front end side of the main body, and both the main body and the intermediate member have a part of the high-pressure channel through which high-pressure fuel flows and fuel having a pressure lower than the fuel pressure in the high-pressure channel. It has a part of the flowing low pressure channel. The main body and the intermediate member are incorporated so that the high-pressure flow paths of each of the main body and the intermediate member communicate with each other, and the low-pressure flow paths of each of the main body and the intermediate member communicate with each other. The path is open at the axial end of the intermediate member.

  The injection nozzle is arranged so that the annular fuel flow path communicates with the high pressure flow path of the intermediate member, and the rear end of the nozzle needle fits into the low pressure flow path of the intermediate member. The annular fuel flow path communicates with the high pressure flow path of the intermediate member to form a part of the high pressure flow path of the injection nozzle, and the tip of the command piston protrudes from the main body toward the front end in the axial direction. The nozzle needle abuts on the rear end portion of the intermediate member in the low pressure flow path of the intermediate member without sliding contact with the nozzle member. Further, the cylindrical member is urged rearward in the axial direction by a predetermined urging means, and comes into liquid-tight contact with the axial end of the intermediate member.

  The rear end portion of the nozzle needle is fitted into the low pressure flow path of the intermediate member, thereby forming a second sliding clearance narrower than the first sliding clearance with the intermediate member. The low-pressure flow path and the low-pressure flow path of the main body are sealed, and the fuel from the high-pressure flow path of the injection nozzle passes through the first sliding clearance and the second sliding clearance in the low-pressure flow path of the intermediate member and the low-pressure flow path of the main body. Flows in at low pressure.

[Configuration of Example]
The structure of the injector 1 of an Example is demonstrated using FIG.
The injector 1 can inject and supply fuel with an ultrahigh pressure injection pressure exceeding 150 MPa. For example, the injector 1 directly injects and supplies fuel into a cylinder of a diesel engine (not shown).

  The injector 1 includes an injection nozzle 2 that injects high-pressure fuel, a main body 3 that receives high-pressure fuel from a fuel supply source such as a common rail and guides the high-pressure fuel toward the injection nozzle 2, and an electromagnetic actuator 4 that opens the injection nozzle 2. And the injection nozzle 2 is fastened to the front end side in the axial direction of the main body 3 and the electromagnetic actuator 4 is fastened to the rear end side in the axial direction of the main body 3.

  The injection nozzle 2 includes a nozzle needle 7 that moves in the axial direction to open and close the nozzle hole 6, and a nozzle body 8 that accommodates the nozzle needle 7 so as to be movable in the axial direction. Here, the nozzle body 8 has a cylinder 9 which is provided in a substantially cylindrical shape and opens at the rear end in the axial direction, and the nozzle needle 7 is urged in a valve closing direction by a spring 11 via a shim 10. The nozzle chamber 12 is formed between the nozzle body 8 and the nozzle body 8.

Then, high pressure fuel is guided to the nozzle chamber 12 from the high pressure flow path 13 of the main body 3, the nozzle chamber 12 forms a part of the high pressure flow path 13, and the fuel pressure in the nozzle chamber 12 is relative to the nozzle needle 7. Acts in the valve opening direction.
Here, the high-pressure channel 13 is a fuel channel through which high-pressure fuel flows, and the high-pressure fuel received from the fuel supply source flows in a state where the pressure is not reduced without passing through various clearances and the like. It is.

  The cylinder 9 is provided with a seat surface 16 on which the seat portion 15 provided at the tip of the nozzle needle 7 is attached and detached, and the nozzle hole 6 is located further on the tip side of the cylinder 9 than the seat surface 16. It is open. For this reason, when the seat portion 15 is attached to and detached from the seat surface 16, the space between the nozzle hole 6 and the nozzle chamber 12 is opened and closed, and fuel injection through the nozzle hole 6 is started or stopped.

  The main body 3 has a control chamber 18 for operating the axial movement of the nozzle needle 7 at the rear end in the axial direction, and has a command piston 19 that transmits the fuel pressure in the control chamber 18 to the nozzle needle 7. The fuel pressure in the control chamber 18 acts on the nozzle needle 7 in the valve closing direction via the command piston 19. The main body 20 is provided with a high-pressure channel 13 so as to guide the high-pressure fuel received from the fuel supply source toward the injection nozzle 2. The high-pressure channel 13 is also branched and connected to the control chamber 18, and high-pressure fuel is guided to the control chamber 18.

Further, the control chamber 18 is provided so as to be opened and closed with respect to the low pressure flow path 23 formed in the electromagnetic actuator 4 by the valve body 22 of the electromagnetic actuator 4.
Here, the low-pressure channel 23 is a fuel channel through which fuel having a pressure lower than the fuel pressure in the high-pressure channel 13 flows, and the fuel flowing through the high-pressure channel 13 passes through various clearances and the like. It is a flow path that flows in a low pressure state.

  For example, the front end side of the control chamber 18 is sealed by the main body 20 slidably supporting the rear end portion of the command piston 19, and the high-pressure fuel in the control chamber 18 is supplied to the main body 20 and the command piston. Leaked into the low-pressure channel 23 through a sliding clearance 24 with respect to 19. The main low-pressure flow path 23 provided in the main body 3 includes an annular main body-side annular low-pressure passage 27 formed between the main body portion 26 and the command piston 19 that are main portions of the main body 20, and a main body-side annular low pressure. This is a main body side low-pressure passage 28 that passes through the main body 26 in the axial direction so as to be parallel to the passage 27.

  Then, the fuel leaked to the main body side annular low pressure passage 27 through the sliding clearance 24 is reversed in the flow direction at the tip of the main body main portion 26 and flows into the main body side low pressure passage 28. Then, the fuel in the main body side low-pressure passage 28 flows into the low-pressure passage 23 of the electromagnetic actuator 4, is led from the rear end of the electromagnetic actuator 4 to the outside of the injector 1, and returns to the fuel tank.

For this reason, when the control chamber 18 is opened with respect to the low pressure flow path 23, the fuel pressure in the control chamber 18 decreases, and when the control chamber 18 is closed with respect to the low pressure flow path 23, the fuel pressure in the control chamber 18 is reduced. To rise.
In addition, an orifice 29 is provided in the inlet-side channel from the high-pressure channel 13 to the control chamber 18, and an orifice 30 is provided in the outlet-side channel from the control chamber 18 to the low-pressure channel 23. The orifices 29 and 30 are provided so that the fuel pressure in the control chamber 18 is surely lowered or raised by the opening / closing operation of the valve body 22.

  The electromagnetic actuator 4 has an armature 33 and a stator 34 that form a magnetic circuit by energizing the solenoid coil 32, and holds the valve element 22 at the axial tip of the sliding shaft portion integrated with the armature 33. The armature 33 is urged by a spring 35 in a direction away from the stator 34.

  As a result, when energization of the solenoid coil 32 is started, the armature 33 is attracted and moved toward the stator 34, the valve element 22 is moved rearward in the axial direction, and the control chamber 18 is opened to the low-pressure channel 23. Is done. When the energization of the solenoid coil 32 is stopped, the armature 33 moves in a direction away from the stator 34 and the valve element 22 moves in the axial direction, so that the control chamber 18 is closed with respect to the low-pressure channel 23. .

  With the above configuration, when the electromagnetic actuator 4 operates by starting energization of the solenoid coil 32, the fuel pressure in the control chamber 18 decreases and the resultant force acting in the axial direction on the nozzle needle 7 increases in the valve opening direction. The nozzle needle 7 moves in the valve opening direction to open the space between the nozzle hole 6 and the nozzle chamber 12, and fuel injection starts.

  Further, when the operation of the electromagnetic actuator 4 is stopped by stopping the energization of the solenoid coil 32, the fuel pressure in the control chamber 18 rises and the resultant force acting in the axial direction on the nozzle needle 7 increases in the valve closing direction. The needle 7 moves in the valve closing direction, the space between the nozzle hole 6 and the nozzle chamber 12 is closed, and fuel injection stops.

[Features of Examples]
The features of the injector 1 of the embodiment will be described with reference to FIG.
First, the injection nozzle 2 has a cylindrical member 37 provided separately from the nozzle body 8.
The cylindrical member 37 supports the rear end portion 38 of the nozzle needle 7 so as to be slidable in the axial direction, and forms a first sliding clearance 39 a between the nozzle needle 7 and the nozzle needle 7. An annular fuel passage 40 is formed between the nozzle body 8 and the nozzle body 8. The nozzle needle 7 is supported so that the rear end portion 38 protrudes rearward in the axial direction from the tubular member 37.

  Further, an intermediate member 41 is disposed on the front end side of the main body 3 in the axial direction, and the intermediate member 41 is sandwiched between the injection nozzle 2 and the main body 3 in the axial direction. The intermediate member 41 has a part of the high-pressure flow path 13 and a part of the low-pressure flow path 23, and the main body 3 and the intermediate member 41 are arranged so that the high-pressure flow paths 13 included therein are in communication with each other. Are incorporated so as to communicate with each other, and the high-pressure channel 13 and the low-pressure channel 23 of the intermediate member 41 are opened at the tip of the intermediate member 41 in the axial direction.

  Further, the low pressure channel 23 of the intermediate member 41 is provided so as to penetrate the central portion of the intermediate member 41 in the axial direction (hereinafter, the low pressure channel 23 provided in the intermediate member 41 is referred to as an intermediate member low pressure channel 41a. .), The high-pressure flow path 13 of the intermediate member 41 is provided so as to penetrate the portion of the intermediate member 41 that is eccentric from the intermediate member low-pressure path 41a in the axial direction (hereinafter, the high-pressure flow provided in the intermediate member 41). The path 13 is referred to as an intermediate member high-pressure path 41b.)

  And by fastening the main body 3 and the intermediate member 41 and the injection nozzle 2, the annular fuel flow path 40 communicates with the high pressure flow path 13 and the intermediate member high pressure path 41 b of the main body 3, so that a part of the high pressure flow path 13 is obtained. (Hereinafter, the annular fuel passage 40 is referred to as a nozzle-side annular high-pressure passage 40). The spring 11 is accommodated in the nozzle-side annular high-pressure path 40.

  Further, by fastening the main body 3 and the intermediate member 41 and the injection nozzle 2, the rear end portion 38 of the nozzle needle 7 is fitted into the opening on the front end side of the intermediate member low-pressure passage 41 a and is slidable on the intermediate member 41. The intermediate member low-pressure passage 41a is blocked by the support. Here, the second sliding clearance 39b formed between the rear end portion 38 and the intermediate member 41 is provided to be narrower than the first sliding clearance 39a.

  Further, the front end of the command piston 19 protrudes from the main body 3 toward the front end side in the axial direction, and comes into contact with the rear end portion 38 in the intermediate member low-pressure path 41 a without sliding contact with the intermediate member 41. The urging force due to the fuel pressure in the control chamber 18 is transmitted to the nozzle needle 7 by the contact between the nozzle needle 7 and the command piston 19 in the intermediate member low pressure passage 41 a.

  The distal end portion 42 of the cylindrical member 37 has a larger outer diameter than the rear portion 43, and functions as a spring seat that supports the spring 11 in the axial direction together with the shim 10. As a result, the cylindrical member 37 is urged rearward in the axial direction by the spring 11, and comes into liquid-tight contact with the axial end of the intermediate member 41.

  The rear part 43 of the cylindrical member 37 is provided with a smaller outer diameter than the tip part 42, and the nozzle-side annular high-pressure path 40 formed between the rear part 43 and the nozzle body 8 is connected to the tip part 42. The cross-sectional area is larger than that of the nozzle-side annular high-pressure passage 40 formed between the nozzle body 8 and the nozzle body 8. Thereby, the communication between the intermediate member high-pressure passage 41b and the nozzle-side annular high-pressure passage 40 is ensured.

  The main body 20 is divided into a main body main portion 26 and a main body tip 46, and the high pressure channel 13 is inclined and penetrates toward the inner peripheral side in the axial direction at the main body tip 46. (Hereinafter, the high-pressure channel 13 of the main body tip portion 46 is referred to as an inclined high-pressure channel 47).

Further, in the main body tip portion 46, the low pressure channel 23 is provided so as to penetrate the central portion in the axial direction (hereinafter, the low pressure channel 23 provided in the axial direction in the central portion of the main body tip portion 46 is connected to the front end. Called the central low pressure passage 47a). Then, by fastening the main body 3 and the intermediate member 41, the front end central low pressure passage 47a and the intermediate member low pressure passage 41a communicate with each other.
Further, the main body tip portion 46 is provided so as to slidably support the tip portion of the command piston 19 in the tip center low-pressure passage 47a, and the command piston 19 includes its own tip portion and rear end portion. Is slidably supported.

  The front end of the command piston 19 mainly ensures the passage of fuel in the front end central low pressure passage 47a and allows the fuel to freely flow between the intermediate member low pressure passage 41a and the main body side through low pressure passage 28. The surface is chamfered and a flat surface 48 parallel to the axial direction is provided. The tip of the command piston 19 protrudes from the tip central low pressure passage 47 a to the tip side, enters the intermediate member low pressure passage 41 a, and contacts the rear end portion 38 of the nozzle needle 7.

  As described above, the fuel flows into the intermediate member low pressure passage 41a from the high pressure passage 13 of the injection nozzle 2 at a low pressure through the first and second sliding clearances 39a and 39b. The fuel leaking into the intermediate member low-pressure passage 41a flows into the main body side low-pressure passage 28 through the tip center low-pressure passage 47a. A recess 49 is provided at the rear end in the axial direction of the main body distal end portion 46 so as to allow communication between the main body-side annular low-pressure passage 27 and the main-body-side through low-pressure passage 28. 23. The tip central low-pressure passage 47 a is open to the recess 49, and the fuel flowing into the tip central low-pressure passage 47 a flows through the recess 49 into the main body side low-pressure passage 28.

  The cylinder 9 is provided such that the central portion and the front end portion in the axial direction are smaller in diameter than the rear end portion, and the nozzle needle 7 is slid by the nozzle body 8 in the central portion of the reduced diameter cylinder 9. It is supported freely. Further, the nozzle needle 7 forms the nozzle chamber 12 by the tip portion 52 on the tip side of the center portion 51 of the nozzle needle 7 which is in sliding contact with the nozzle body 8. In the central portion 51, the outer peripheral surface is chamfered and a flat surface 53 parallel to the axial direction is provided in order to ensure communication between the nozzle-side annular high-pressure passage 40 and the nozzle chamber 12.

[Effects of Examples]
According to the injector 1 of the embodiment, the injection nozzle 2 includes the cylindrical member 37 that supports the nozzle needle 7 so as to be slidable in the axial direction and forms a first sliding clearance 39 a between the nozzle needle 7 and the injection nozzle 2. Have. Further, the nozzle needle 7 and the cylindrical member 37 are accommodated in the cylinder 9 to form a nozzle side annular high pressure passage 40 between the nozzle needle 7 and the nozzle body 8, and the nozzle side annular high pressure passage 40 is interposed via an intermediate member high pressure passage 41b. The main body 3 communicates with the inclined high pressure passage 47.

  Furthermore, the rear end portion 38 of the nozzle needle 7 protrudes rearward in the axial direction from the cylindrical member 37 to block the intermediate member low-pressure passage 41a, and is slidably supported by the intermediate member 41 so as to be between the intermediate member 41 and the intermediate member 41. A second sliding clearance 39b is formed. Further, the cylindrical member 37 is urged rearward in the axial direction by the spring 11 and is in liquid-tight contact with the axial front end of the intermediate member 41. Then, the fuel flows into the intermediate member low-pressure passage 41a from the high-pressure passage 13 of the injection nozzle 2 at a low pressure through the first and second sliding clearances 39a and 39b.

  Thereby, in order to provide the high-pressure channel 13 in the injection nozzle 2, the nozzle-side annular high-pressure channel 40 and the nozzle-side annular high-pressure channel 40 can be formed without forming a bag hole or providing a side channel in the nozzle body 8 and connecting it to the bag hole. By communicating with the intermediate member high pressure passage 41 b and the inclined high pressure passage 47, high pressure fuel can be supplied into the injection nozzle 2. For this reason, it is possible to increase the injection pressure without considering the pressure-resistance reduction of the protrusions caused by the connection between the bag hole and the side flow path.

Further, even if the fuel passing through the first sliding clearance 39a is increased as the injection pressure is increased, the high pressure fuel pressure acts on the cylindrical member 37 from the outer peripheral side, so that the first sliding clearance 39a is applied. No longer expands.
As described above, a situation that is considered to be actualized as the injection pressure is increased (decrease in pressure resistance of the protrusion caused by the connection between the bag hole and the side flow path, and the first sliding formed on the outer periphery of the nozzle needle 7. (Expansion of the clearance 39a) can be avoided.

  In addition, by dividing the sliding clearance formed on the outer periphery of the nozzle needle 7 into the first and second sliding clearances 39a and 39b in series with respect to the flow of the leaked fuel, the fuel in the high-pressure flow path 13 is determined with respect to the leak amount. The pressure can be reduced by the first sliding clearance 39a when the pressure is high, and can be reduced by the second sliding clearance 39b when the fuel pressure in the high-pressure channel 13 is medium or low. For this reason, even if the injection pressure is changed in a wide range from a low intermediate pressure of 20 MPa to 100 MPa as in idling to a high pressure exceeding 150 MPa, the leak amount can be maintained at a small amount.

For example, when the low pressure flow path 23 is formed on the inner peripheral side of the cylindrical member 37 without causing the rear end portion 38 of the nozzle needle 7 to protrude rearward in the axial direction from the cylindrical member 37, the fuel in the nozzle side annular high pressure path 40 The rear portion 43 of the cylindrical member 37 is deformed to the inner peripheral side by the pressure difference between the pressure and the fuel pressure of the low pressure flow path 23 on the inner peripheral side of the cylindrical member 37.
The amount of deformation of the rear portion 43 is larger as the fuel pressure in the high-pressure channel 13 is higher, and as the amount of deformation of the rear portion 43 is larger, the first sliding clearance 39a is narrowed and the possibility of occurrence of “clamping” increases. .

  Therefore, assuming that the injection pressure is high and there is a high possibility of “clamping”, the first sliding clearance 39a is set to be large in consideration of the deformation amount of the rear portion 43 when the injection pressure is high. To do. As a result, even if the injection pressure becomes high and the deformation amount of the rear part 43 increases, the amount of fuel leaking through the first sliding clearance 39a is suppressed while suppressing the possibility of occurrence of “holding”. be able to.

  If the first sliding clearance 39a is set to a large value, the amount of deformation of the rear portion 43 is reduced when the injection pressure is medium and low, and the amount of fuel leaking through the first sliding clearance 39a is increased. End up. Therefore, the second sliding clearance 39b is set to be narrower than the first sliding clearance 39a. Thereby, when the injection pressure is medium and low, the second sliding clearance 39b can suppress the fuel that has flowed into the first sliding clearance 39a from leaking to the intermediate member low pressure passage 41a.

  In the intermediate member 41, the portion that slidably supports the rear end portion 38 of the nozzle needle 7 (that is, the flow path wall vicinity portion 55 that forms the intermediate member low-pressure passage 41a) is deformed inward on the entire circumference. It is not structured to receive fuel pressure.

  That is, the flow path wall vicinity 55 has an annular shape to form the intermediate member low pressure passage 41a, but when the circumferential coordinate is considered with the axis of the intermediate member low pressure passage 41a as the central axis, Of the portion 55, the fuel pressure is applied so that only the portion where the circumferential coordinate coincides with the intermediate member high-pressure path 41b is deformed to the inner peripheral side, and the other portion is not subjected to the fuel pressure deformed to the inner peripheral side. . For this reason, in the intermediate member 41, even if the injection pressure becomes high, there is a very low possibility that “clogging” will occur.

  The rear end portion 38 of the nozzle needle 7 is slidably supported by the intermediate member 41 to form a second sliding clearance 39b and block the intermediate member low-pressure path 41a. The intermediate member low-pressure path 41 a is in contact with the rear end portion 38 without being slidably supported by 41. Thereby, the assembling work of the intermediate member 41 can be performed in consideration of only the accuracy of the second sliding clearance 39b without considering the sliding support of the command piston 19. For this reason, since the axial shift management of the intermediate member 41 can be relaxed, the number of work steps involved in manufacturing and the like can be reduced.

[Modification]
The aspect of the injector 1 is not limited to an Example, Various modifications can be considered. For example, the cylindrical member 37 may be provided with a high-strength ceramic such as silicon nitride having higher rigidity than steel, so that deformation of the cylindrical member 37 toward the inner peripheral side may be suppressed.

DESCRIPTION OF SYMBOLS 1 Injector 2 Injection nozzle 3 Main body 6 Injection hole 7 Nozzle needle 8 Nozzle body 9 Cylinder 11 Spring (biasing means)
13 High-pressure channel 18 Control chamber 19 Command piston 23 Low-pressure channel 37 Cylindrical member 38 Rear end (rear end of nozzle needle)
39a First sliding clearance 39b Second sliding clearance 40 Nozzle side annular high pressure passage (annular fuel passage, high pressure passage of injection nozzle)
41 Intermediate member 41a Intermediate member low pressure passage (Low pressure passage of intermediate member)
41b Intermediate member high-pressure path (intermediate member high-pressure flow path)
47 Inclined high-pressure channel (main body high-pressure channel)
47a Central low pressure channel at the tip

Claims (1)

Injector comprising: an injection nozzle for injecting high-pressure fuel; and a main body for receiving high-pressure fuel from a fuel supply source, the injector being configured by fastening the injection nozzle to the front end side in the axial direction of the main body.
The spray nozzle is
A nozzle needle that is accommodated in a nozzle body having a nozzle hole and moves in the axial direction to open and close the nozzle hole;
A cylindrical shape that is provided in a cylindrical shape separate from the nozzle body, and that supports the nozzle needle so as to be slidable in the axial direction on the inner peripheral side and forms a first sliding clearance with the nozzle needle. And having a member
The nozzle body has a cylinder that is provided in a substantially cylindrical shape and opens at the rear end in the axial direction and communicates with the nozzle hole.
The nozzle needle and the cylindrical member are accommodated in the cylinder to form an annular fuel flow path between the nozzle needle and the nozzle body, and a rear end portion of the nozzle needle protrudes rearward in the axial direction from the cylindrical member. And
The main body forms a control chamber for manipulating the movement of the nozzle needle in the axial direction, and a command piston that contacts the rear end of the nozzle needle and transmits fuel pressure in the control chamber to the nozzle needle. Have
An intermediate member is disposed on the axial front end side of the main body,
The main body and the intermediate member both have a part of a high-pressure channel through which high-pressure fuel flows, and a part of a low-pressure channel through which fuel having a pressure lower than the fuel pressure of the high-pressure channel flows.
The main body and the intermediate member are incorporated so that the high-pressure flow paths of the main body and the intermediate member communicate with each other, and the low-pressure flow paths of the main body and the intermediate member communicate with each other. The flow path is opened at the axial end of the intermediate member,
The injection nozzle includes the intermediate member such that the annular fuel flow path communicates with the high pressure flow path of the intermediate member, and a rear end portion of the nozzle needle is fitted into the low pressure flow path of the intermediate member. The annular fuel flow path communicates with the high pressure flow path of the intermediate member to form a part of the high pressure flow path of the injection nozzle, and the front end of the command piston extends from the main body. Abutting the rear end portion of the nozzle needle in the low pressure flow path of the intermediate member without protruding in the axial front end side and in sliding contact with the intermediate member,
The cylindrical member is urged rearward in the axial direction by a predetermined urging means and is in liquid-tight contact with the axial tip of the intermediate member,
The rear end portion of the nozzle needle is fitted into the low pressure flow path of the intermediate member, thereby forming a second sliding clearance narrower than the first sliding clearance with the intermediate member. Blocking the low pressure flow path of the intermediate member and the low pressure flow path of the main body,
Fuel flows into the low pressure channel of the intermediate member and the low pressure channel of the main body from the high pressure channel of the injection nozzle through the first sliding clearance and the second sliding clearance. Injector.

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