JP2012184717A - Injector manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deformation of an inner periphery of an accommodation hole 35 and an outer periphery of an injector body 2 even when autofrettage is applied to a high-pressure hole 34 in the injector body 2 of an injector having the high-pressure hole 34 which leads a high-pressure fuel.SOLUTION: In a process for improving pressure resistance of the injector, in a state where a column jig 37 having a diameter approximately the same as a hole diameter of the accommodation hole 35 is inserted into the accommodation hole 35, autofrettage is applied to the high-pressure hole 34. Further, while the column jig 37 is inserted into the accommodation hole 35, in a state where a tubular jig 38 having an inner diameter approximately the same as an outer diameter of the injector body 2 is externally inserted into the injector body 2, autofrettage is applied to the high-pressure hole 34. By this means, even when compressive residual stress is given to a hole wall of the high-pressure hole 34, it is possible to suppress deformation of the inner periphery of the accommodation hole 35 by the column jig 37 and it is also possible to suppress deformation of the outer periphery of the injector body 2 by the tubular jig 38.

Description

  The present invention relates to an injector manufacturing method for injecting and supplying fuel to an internal combustion engine.

  Conventionally, as shown in FIG. 4, a main body 101 that receives high-pressure fuel from a fuel supply source, and a high-pressure fuel that is fastened to the front end side in the axial direction of the main body 101 are received and injected into the injector 100. A device that includes an injection nozzle 102 and an electromagnetic valve 103 that is housed in the main body 101 and functions as an actuator of the injection nozzle 102 is known. Further, according to the injector 100, the main body 101 has the high-pressure hole 105 that guides the received high-pressure fuel to the injection nozzle 102, and the accommodation hole 106 that accommodates the electromagnetic valve 103.

By the way, in the common rail which comprises a fuel-injection apparatus with the injector 100, the technique of providing a residual compressive stress by an autofretage is known as a means to improve pressure | voltage resistance (for example, refer patent document 1).
According to Patent Document 1, by injecting a pressure application medium into a space or a passage where high-pressure fuel flows in a common rail, the wall surface is plastically deformed, and the region near the wall surface connected to the plastically deformed wall surface is elastically deformed and residual compression is performed. Stress is applied to increase pressure resistance.

  Therefore, it is conceivable to apply auto-fraget to the main body 101 of the injector 100. That is, by applying auto-fretting to the high-pressure hole 105 through which high-pressure fuel flows in the main body 101, it is possible to impart residual compressive stress to the vicinity of the hole wall and enhance pressure resistance.

  However, if autofrettage is applied to the high-pressure hole 105, the inner periphery of another hole or the outer periphery of the main body 101 that does not need to be subjected to autofragement such as the accommodation hole 106 is also deformed due to deformation of the vicinity of the hole wall of the high-pressure hole 105. Resulting in. Therefore, there is a demand for a configuration that can suppress deformation of the inner periphery of another hole other than the high-pressure hole 105 and the outer periphery of the main body 101 even when the high-pressure hole 105 is subjected to autofrettage.

JP 2010-159676 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a high-pressure hole in the main body of an injector having a high-pressure hole for guiding high-pressure fuel, It is in providing the structure etc. which can suppress the deformation | transformation of the inner periphery of another hole other than these, or the outer periphery of a main body.

[Means of Claim 1]
According to the first aspect of the present invention, the injector includes a main body that receives high-pressure fuel from a fuel supply source, and an injection nozzle that is fastened to the front end in the axial direction of the main body and receives high-pressure fuel from the main body and injects it. The main body has a high-pressure hole that guides the received high-pressure fuel to the injection nozzle, and another hole that is provided separately from the high-pressure hole.

And this manufacturing method of an injector is equipped with the pressure resistance improvement process which gives compression residual stress to the hole wall of a high-pressure hole by auto-fretage, and has a diameter which corresponds in general to the hole diameter of another hole in a pressure resistance improvement process. With the columnar jig inserted into another hole, auto-frettage is applied to the high-pressure hole.
Thereby, even if compressive residual stress is given to the hole wall of the high-pressure hole, the deformation of the inner periphery of the other hole can be suppressed by the columnar jig.

[Means of claim 2]
According to the means of claim 2, in the pressure resistance improving step, the columnar jig is inserted into another hole, and the main body is inserted into a cylindrical jig having an inner diameter substantially coinciding with the outer diameter of the main body. Auto fretage is applied to the hole.
Thereby, while the deformation | transformation of the inner periphery of another hole can be suppressed with a columnar jig | tool, the deformation | transformation of the outer periphery of a main body can be suppressed with a cylindrical jig | tool.

[Means of claim 3]
According to the means of claim 3, the diameter of the columnar jig is reduced in a conical shape toward one end, and one end of the columnar jig is inserted into another hole in the pressure resistance improving step.
Thereby, insertion and extraction of the columnar jig can be easily performed.

[Means of claim 4]
According to the fourth aspect of the present invention, the injector includes an electromagnetic valve that is accommodated in the main body and functions as an actuator for the injection nozzle, and the other hole is an accommodation hole that accommodates the electromagnetic valve.
Thereby, in the injector which accommodates an electromagnetic valve in the accommodation hole of a main part, a deformation | transformation of the inner periphery of an accommodation hole can be suppressed and an electromagnetic valve can be accommodated smoothly.

[Means of claim 5]
According to the means of claim 5, the columnar jig is divided into a plurality of parts.
Thereby, insertion and extraction of the columnar jig can be easily performed.

It is a principal part block diagram of an injector (Example 1). It is sectional drawing which shows the state which set the columnar jig | tool and the cylindrical jig | tool to the main body of the injector (Example 1). (A) is a side view of a columnar jig | tool, (b) is a bottom view which shows the state which set the columnar jig | tool to the main body of an injector (Example 2). (A) is a principal part block diagram of an injector, (b) is explanatory drawing which shows the deformation | transformation by an autofretage (conventional example).

  The injector manufactured by the manufacturing method according to the first embodiment includes a main body that receives high-pressure fuel from a fuel supply source, and an injection nozzle that is fastened to the front end in the axial direction of the main body and receives high-pressure fuel from the main body and injects it. . The main body has a high-pressure hole that guides the received high-pressure fuel to the injection nozzle, and another hole that is provided separately from the high-pressure hole.

And the manufacturing method of the injector of Embodiment 1 is equipped with the pressure | voltage resistance improvement process which gives a compressive residual stress to the hole wall of a high-pressure hole by an autofretage, and substantially corresponds to the hole diameter of another hole in a pressure | voltage resistance improvement process. With a columnar jig having a diameter inserted into another hole, auto-frettage is applied to the high-pressure hole.
In the pressure resistance improving process, the columnar jig is inserted into another hole, and the high-pressure hole is subjected to autofrettage while the main body is inserted into a cylindrical jig having an inner diameter substantially matching the outer diameter of the main body. .

Further, the diameter of the columnar jig is reduced in a conical shape toward one end, and one end of the columnar jig is inserted into another hole in the pressure resistance improving step.
In addition, the injector manufactured by the manufacturing method of Embodiment 1 is equipped with the electromagnetic valve accommodated in a main body and functions as an actuator of an injection nozzle, and another hole is an accommodation hole which accommodates an electromagnetic valve.
According to the injector manufacturing method of the second embodiment, the columnar jig is divided into a plurality of parts.

[Configuration of Example 1]
The structure of the injector 1 of Example 1 is demonstrated using FIG.
The injector 1 is capable of injecting and supplying fuel with an ultrahigh injection pressure exceeding 100 MPa. For example, the injector 1 is mounted on a diesel engine (not shown) and directly supplies fuel to a combustion chamber (not shown). Supply to the jet.

  The injector 1 includes a main body 2 that receives high-pressure fuel from a fuel supply source (not shown), an injection nozzle 3 that receives and injects high-pressure fuel from the main body 2, and an electromagnetic valve 5 that functions as an actuator for the injection nozzle 3. And the injection nozzle 3 is fastened to the tip end side in the axial direction of the main body 2 via the chip packing 6 and the electromagnetic valve 5 is accommodated in the main body 2.

  In the following description, the term “axial direction” means the axial direction of the injector 1 unless otherwise specified. The main body 2 and the injection nozzle 3 are coaxial, and the injectors 1, the main body 2 and the injection nozzle 3 all have the same axis.

  The injection nozzle 3 includes a nozzle needle 9 that moves in the axial direction to open and close the nozzle hole 8, a nozzle body 10 that supports and accommodates the nozzle needle 9 slidably in the axial direction, and a direction in which the nozzle hole 8 is closed. A coil spring 11 for urging the nozzle needle 9 (hereinafter referred to as a valve closing direction), and a tubular member 13 for forming a back pressure chamber 12 for applying fuel pressure to the nozzle needle 9 in the valve closing direction; Have The nozzle body 10 has a cylinder 14 which is provided in a substantially cylindrical shape and opens at the rear end in the axial direction, and the nozzle needle 9 is slidably supported by the cylinder 14 and accommodated therein.

The cylinder 14 is in communication with the high pressure flow path 16 provided in the main body 2 and the chip packing 6 by fastening the main body 2 and the injection nozzle 3 via the chip packing 6. High pressure fuel is led from 16.
The high-pressure channel 16 is a channel through which the high-pressure fuel received from the fuel supply source flows without passing through various clearances and the like and not being reduced in pressure.

  The nozzle needle 9 forms a sliding shaft portion 18 whose central portion is slidably supported by the nozzle body 10. The nozzle needle 9 is a nozzle for exerting fuel pressure in a direction (hereinafter referred to as a valve opening direction) in which the nozzle hole 9 is opened with respect to the nozzle needle 9 by a portion on the tip side of the sliding shaft portion 18. A chamber 19 is formed.

  In addition, the nozzle needle 9 forms a spring chamber 20 that houses the coil spring 11 by a portion on the rear end side of the sliding shaft portion 18, and high-pressure fuel flows into the spring chamber 20 from the high-pressure channel 16. . Further, the sliding shaft portion 18 is chamfered at a part of its outer peripheral surface in order to ensure communication between the nozzle chamber 19 and the spring chamber 20 and guide high-pressure fuel to the nozzle chamber 19.

  The cylinder 14 is provided with a seat surface 22 to which a circular sheet portion 21 provided at the tip of the nozzle needle 9 is attached and detached, and the nozzle hole 8 is located further on the tip side than the seat surface 22. 14 is open. For this reason, when the seat portion 21 is detached from the seat surface 22, the opening between the nozzle hole 8 and the nozzle chamber 19 is opened and closed, and fuel injection through the nozzle hole 8 is started or stopped.

Further, the rearmost end portion of the nozzle needle 9 forms a second sliding shaft portion 24 that is slidably supported in the axial direction by the cylindrical member 13.
Here, the coil spring 11 is set so as to be expandable and contractable in the axial direction by a shim 25 disposed at the rear end of the sliding shaft portion 18 and the tubular member 13, and is accommodated in the spring chamber 20. Thus, the coil spring 11 urges the nozzle needle 9 toward the axial front end side (valve closing direction), and urges the cylindrical member 13 toward the axial rear end side to press-contact the tip packing 6. .

  For this reason, the inner peripheral region of the cylindrical member 13 is sealed at the front end side by the second sliding shaft portion 24 and at the rear end side by the chip packing 6. And the function as the back pressure chamber 12 is provided because high pressure fuel flows in and out of this sealed inner peripheral region.

  That is, the tip packing 6 is provided with an inflow path 27 for allowing high-pressure fuel to flow into the back pressure chamber 12 and an outflow path 28 for allowing fuel to flow out from the back pressure chamber 12. Restrictions 29 and 30 are provided in each of the paths 28. The injection nozzle 3 and the tip packing 6 are fastened so that both the inflow path 27 and the outflow path 28 are connected to the back pressure chamber 12.

Further, the inflow path 27 is provided so as to branch from the high-pressure flow path 16 in the tip packing 6, and the outflow path 28 is formed in, for example, the electromagnetic valve 5 by a valve body (not shown) of the electromagnetic valve 5. It is provided so as to be opened and closed with a low-pressure channel (not shown) provided.
Here, the low-pressure channel is a fuel channel through which a fuel whose pressure is significantly lower than the fuel pressure in the high-pressure channel 16 flows, and the high-pressure fuel flows in a state where the pressure is reduced by passing through various clearances and the like. This is a flow path.

  For this reason, the fuel pressure (back pressure) in the back pressure chamber 12 is changed by varying the flow state of the fuel into the back pressure chamber 12 via the inflow passage 27 and the outflow passage 28 according to the operation of the electromagnetic valve 5. The nozzle needle 9 can be driven in the valve closing direction or the valve opening direction by increasing / decreasing.

  The throttles 29 and 30 are provided so that the back pressure is reliably reduced by the communication between the outflow passage 28 and the low pressure passage by opening the solenoid valve 5. The throttle 30 is provided at the downstream end of the outflow passage 28 and opens at the rear end face of the tip packing 6. The opening at the rear end face of the tip packing 6 of the throttle 30 is the flow of fuel in the back pressure chamber 12. Make an exit 32.

  The main body 2 has a high-pressure hole 34 that guides the received high-pressure fuel to the injection nozzle 3, and an accommodation hole 35 that accommodates the electromagnetic valve 5. Here, the accommodation hole 35 is provided in parallel to the axial direction at a position eccentric from the axial center of the injector 1. The high-pressure hole 34 is provided parallel to the axial direction at a position eccentric to the opposite side of the accommodation hole 35 in the radial direction, and forms the high-pressure channel 16 of the main body 2. The high-pressure hole 34 has a significantly smaller diameter than the accommodation hole 35.

  The solenoid valve 5 opens the outlet 32 to the low-pressure channel by energizing a solenoid coil (not shown), and closes the outlet 32 to the low-pressure channel by stopping energization of the solenoid coil. It has a well-known configuration.

  With the above configuration, when energization of the solenoid coil of the solenoid valve 5 is started and the outlet port 32 is opened to the low pressure flow path, the back pressure is reduced and the resultant force acting in the axial direction on the nozzle needle 9 is generated. Increases in the valve opening direction. For this reason, the nozzle needle 9 is driven in the valve opening direction, the space between the nozzle hole 8 and the nozzle chamber 19 is opened, and fuel injection starts.

  Further, when energization to the solenoid coil is stopped and the outlet 32 is closed with respect to the low pressure flow path, the back pressure increases and the resultant force acting in the axial direction on the nozzle needle 9 increases in the valve closing direction. . For this reason, the nozzle needle 9 is driven in the valve closing direction, the space between the nozzle hole 8 and the nozzle chamber 19 is closed, and fuel injection stops.

[Production Method of Example 1]
The manufacturing method of the injector 1 of Example 1 is demonstrated using FIG.
First, the method for manufacturing the injector 1 includes a pressure resistance improving process for applying compressive residual stress to the hole wall of the high-pressure hole 34 by auto-fretting.
In the pressure resistance improving step, autofrettage is applied to the high-pressure hole 34 in a state where the columnar jig 37 having a diameter substantially matching the hole diameter of the accommodation hole 35 is inserted into the accommodation hole 35. Here, the diameter of the columnar jig 37 is reduced in a conical shape toward one end, and one end of the columnar jig 37 is inserted into the accommodation hole 35.

  Further, in the pressure resistance improving step, the columnar jig 37 is inserted into the accommodation hole 35 and the high-pressure hole 34 is inserted in the state where the main body 2 is inserted into the cylindrical jig 38 having an inner diameter substantially equal to the outer diameter of the main body 2. Auto fretage is applied.

[Effect of Example 1]
According to the method for manufacturing the injector 1 of the first embodiment, in the pressure resistance improving process, the columnar jig 37 having a diameter substantially equal to the hole diameter of the accommodation hole 35 is inserted into the accommodation hole 35 and the high-pressure hole 34 is automatically inserted. Apply freage.
Thereby, even if compressive residual stress is applied to the hole wall of the high-pressure hole 34, deformation of the inner periphery of the accommodation hole 35 can be suppressed by the columnar jig 37.

Further, in the pressure resistance improving step, the columnar jig 37 is inserted into the accommodation hole 35 and the high-pressure hole 34 is inserted in the state where the main body 2 is inserted into the cylindrical jig 38 having an inner diameter substantially equal to the outer diameter of the main body 2. Auto fretage is applied.
Thereby, deformation of the inner periphery of the accommodation hole 35 can be suppressed by the columnar jig 37, and deformation of the outer periphery of the main body 2 can be suppressed by the cylindrical jig 38.

Further, the diameter of the columnar jig 37 is reduced in a conical shape toward one end, and one end of the columnar jig 37 is inserted into the accommodation hole 35 in the pressure resistance improving process.
Thereby, insertion and extraction of the columnar jig 37 can be easily performed.

Further, the injector 1 includes an electromagnetic valve 5 that functions as an actuator for the injection nozzle 3, and a columnar jig 37 is inserted into the accommodation hole 35 that accommodates the electromagnetic valve 5, so that the high-pressure hole 34 is subjected to auto-fretting.
Thereby, the electromagnetic valve 5 can be accommodated smoothly by suppressing deformation of the inner periphery of the accommodation hole 35 due to the auto-frettage process of the high-pressure hole 34.

[Example 2]
According to the method for manufacturing the injector 1 of the second embodiment, the columnar jig 37 is divided into, for example, three parts 37a, 37b, and 37c.
Thereby, insertion and extraction of the columnar jig 37 can be easily performed.

[Modification]
The mode of the injector 1 is not limited to the first and second embodiments, and various modifications can be considered.
For example, according to the injector 1 of the first and second embodiments, the low pressure flow path communicating with the outflow path 28 is provided in the electromagnetic valve 5, but the low pressure flow path is provided in the main body 2 separately from the high pressure hole 34 and the accommodation hole 35. May be provided to communicate with the outflow passage 28. In this case, a columnar jig 37 is separately provided for the low-pressure flow path provided in the main body 2, and the columnar jig 37 is inserted not only in the accommodation hole 35 but also in the low-pressure flow path provided in the main body 2. In addition, it is possible to suppress the inner periphery of the low pressure flow path from being deformed along with the autofrettage processing of the high pressure hole 34.

  Further, according to the injectors 1 of the first and second embodiments, the back pressure directly acts on the nozzle needle 9. For example, the command piston is supported in the main body 2 so as to be slidable in the axial direction. The back pressure chamber 12 may be formed on the rear end side of the command piston by contacting the rear end, and the back pressure may be applied to the nozzle needle 9 via the command piston. In this case, by inserting the columnar jig 37 into the hole that accommodates the command piston, it is possible to suppress the inner periphery of the hole that accommodates the command piston from being deformed along with the autofrettage processing of the high-pressure hole 34. .

DESCRIPTION OF SYMBOLS 1 Injector 2 Main body 3 Injection nozzle 5 Solenoid valve 34 High-pressure hole 35 Accommodation hole (separate hole)
37 Columnar jig 38 Cylindrical jigs 37a to 37c Parts

Claims (5)

A main body (2) that receives high-pressure fuel from a fuel supply source, and an injection nozzle (3) that is fastened to the axial front end side of the main body (2) and receives high-pressure fuel from the main body (2) and injects it. Prepared,
The main body (2) has an injector (1) having a high-pressure hole (34) for guiding the received high-pressure fuel to the injection nozzle (3) and another hole (35) provided separately from the high-pressure hole (34). )
A pressure resistance improving step of applying compressive residual stress to the hole wall of the high-pressure hole (34) by auto-fraget,
In this pressure resistance improving step, the auto jig is inserted into the high-pressure hole (34) with a columnar jig (37) having a diameter substantially equal to the hole diameter of the separate hole (35) being inserted into the separate hole (35). A method of manufacturing an injector (1), characterized by applying a tee. In the manufacturing method of the injector (1) according to claim 1,
In the pressure resistance improving step, the columnar jig (37) is inserted into the separate hole (35), and the cylindrical jig (38) having an inner diameter substantially matching the outer diameter of the main body (2) is inserted into the cylindrical jig (38). A method of manufacturing an injector (1), characterized in that autofrettage is applied to the high-pressure hole (34) with the main body (2) inserted. In the manufacturing method of the injector (1) according to claim 1 or 2,
The columnar jig (37) is conically reduced in diameter toward one end,
In the pressure resistance improving process, one end of the columnar jig (37) is inserted into the separate hole (35). In the manufacturing method of the injector (1) as described in any one of Claims 1 thru | or 3,
The injector (1) includes a solenoid valve (5) housed in the main body (2) and functioning as an actuator for the injection nozzle (3),
The method for manufacturing an injector (1), wherein the separate hole (35) is a housing hole (35) for housing the electromagnetic valve (5). In the manufacturing method of the injector (1) according to any one of claims 1 to 4,
The method of manufacturing an injector (1), wherein the columnar jig (37) is divided into a plurality of parts (37a, 37b, 37c).

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