JP2012202251A - Injector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injector that can achieve desired injection characteristics at low cost.SOLUTION: An injector 1 includes a control valve 10 for adjusting a fuel pressure in a control chamber 4 of the nozzle needle 3, and the control valve 10 communicates between a low pressure flow passage 6 and the control chamber 4 by a valve element 19 being pushed by a rod 36 of an actuator 11. The rod 36 includes a sliding part 36a slidably supported by a rod holding part 10a, and an in-passage rod part 36b contained in a flow passage forming chamber 25. Further, the in-passage rod part 36b has a smaller diameter part 38 having an outer diameter smaller than the sliding part 36a. According to this, by securing strength of the rod 36 mainly by the sliding part 36a and reducing the diameter of the in-passage rod part 36b, a flexibility in designing the flow passage forming chamber 25 forming a part of an outflow passage can be secured. Therefore, the flexibility in designing the flow passage forming chamber 25 can be improved at low cost, and the desired injection characteristics can be achieved.

Description

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

  As shown in FIG. 3, as a conventional injector 100, a nozzle needle 102, a control chamber 103 for applying a fuel pressure to the nozzle needle 102 in a valve closing direction, and a control for adjusting the fuel pressure in the control chamber 103. There is a valve that includes a valve 104 and an actuator 105 that drives the control valve 104, and a valve body 109 of the control valve 104 is driven by a rod 108 that is driven by the actuator 105 (see Patent Document 1).

  The control valve 104 is formed on the upper sheet 110 on which the valve body 109 is seated and separated from the other end side in the axial direction, and on the one end side in the axial direction of the upper seat 110, and the valve body 109 is seated on the upper seat 110. It sometimes has a flow path forming chamber 113 that forms a part of an outflow path through which fuel flows out from the control chamber 103 to the low pressure flow path 111.

In the control valve 104 having the above structure, the specifications of the rod 108 are determined by the upper seat diameter d, the rigidity of the rod 108, and the force and displacement that the actuator 105 can generate.
Since the rod 108 protrudes into the flow path forming chamber 113, the volume of the space that can be used as the outflow flow path in the flow path forming chamber 113 is determined by the diameter of the rod 108. Therefore, the degree of freedom in designing the flow path forming chamber 113 as the outflow flow path is low due to the specifications of the rod 108.

For this reason, even if it is desired to make an appropriate design in order to obtain a desired injection characteristic, there are cases in which an appropriate design cannot be made due to the restriction of the degree of freedom in design.
For example, when the rod diameter is large, when designing the flow path forming chamber 113, the space that can be used as the outflow flow path cannot be made large, and the decompression of the control chamber 103 due to the fuel outflow from the outflow flow path is prevented. In some cases, the nozzle lift is delayed, and the target injection characteristics cannot be obtained.
That is, the desired injection characteristics may not be obtained due to the low degree of design freedom.

  In order to increase the degree of freedom in designing the flow path forming chamber 113, it is conceivable to reduce the rod diameter. However, when the rod diameter is reduced, a highly rigid material must be used to ensure the required strength. This has the problem of increasing costs.

  Also, a method of increasing the design freedom of the flow path forming chamber 113 by increasing the upper sheet diameter d is conceivable. In this case, however, the force required to push the valve body 109 increases, so that the actuator There arises the problem of increasing the size of 105 and increasing the cost.

JP 2009-127491 A

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an injector capable of obtaining desired injection characteristics at low cost.

[Means of Claim 1]
The injector according to claim 1 includes a nozzle needle (3) for opening and closing the nozzle hole (2), a control chamber (4) for applying fuel pressure to the nozzle needle (3) in a valve closing direction, a low pressure A control valve (10) for adjusting the fuel pressure in the control chamber (4), and a control valve (10) having a valve body (19) for opening and closing communication between the flow path (6) and the control chamber (4) And an actuator (11) for driving the motor.
The actuator (11) has a rod (36) that abuts from one end side in the axial direction of the valve body (19) of the control valve (10) and pushes the valve body (19) into the other end side in the axial direction. .

  The control valve (10) is formed on the one end side in the axial direction of the upper seat (30) on which the valve body (19) is separated from the other end side in the axial direction, and the valve body (19). Has a flow path forming chamber (25) that forms part of an outflow path for allowing fuel to flow out from the control chamber (4) to the low pressure flow path (6) when the vehicle is separated from the upper seat (30). ing.

  The rod (36) is formed on a sliding portion (36a) that is slidably supported by a predetermined body, on the other end side in the axial direction of the sliding portion (36a), and on the flow path forming chamber (25). ) In the flow path, and the flow path rod part (36b) has a small diameter part (38) having an outer diameter smaller than that of the sliding part (36a).

According to this, the flow path which forms a part of the outflow flow path by reducing the diameter of the in-flow path rod portion (36b) while ensuring the strength of the rod (36) mainly in the sliding portion (36a). The design freedom of the formation chamber (25) can be ensured.
For this reason, the design freedom of the flow path forming chamber (25) can be increased without cost, and desired injection characteristics can be obtained.
In addition, the diameter of the rod part (36b) in the flow path is determined so as to satisfy the deformation amount allowed for the entire rod from the generated force and displacement of the actuator (11).

[Means of claim 2]
According to the injector of claim 2, the flow path rod portion (36b) has an outer diameter of the other axial end portion (39) that abuts the valve body (19) larger than one axial end side.
According to this, the rigidity of the part contact | abutted to a valve body (19) can be made high.

[Means of claim 3]
According to the injector of the third aspect, the in-channel rod portion (36b) is smaller in diameter than the sliding portion (36a), and the diameter becomes smaller toward the other end side in the axial direction.
This means shows one mode of the small diameter part of the rod part (36b) in the flow path.

(A) is the whole block diagram of an injector, (b) is the principal part enlarged view of (a) (Example 1). (A) is a figure explaining the rod shape of Example 2, (b)-(d) is a figure explaining the rod shape of Example 3 (Example 2, 3). (A) is a whole block diagram of an injector, (b) is a principal part enlarged view of (a) (conventional example).

According to the injector of the embodiment for carrying out the invention, the actuator (11) abuts from one end side in the axial direction of the valve body (19) of the control valve (10) to bring the valve body (19) to the other end side in the axial direction. Rod (36) for pushing into
The control valve (10) is formed on the upper seat (30) from which the valve body (19) is separated from the other end side in the axial direction and on one end side in the axial direction of the upper seat (30). 19) a flow path forming chamber (25) that forms a part of the outflow channel that allows the fuel to flow out from the control chamber (4) to the low pressure channel (6) when the upper seat (30) is seated. Have.

  The rod (36) is formed on a sliding portion (36a) that is slidably supported by a predetermined body, on the other end side in the axial direction of the sliding portion (36a), and on the flow path forming chamber (25). ) In the flow path, and the flow path rod part (36b) has a small diameter part (38) having an outer diameter smaller than that of the sliding part (36a).

[Configuration of Example 1]
The structure of the injector 1 of Example 1 is demonstrated using FIG.
A nozzle needle 3 for opening and closing the nozzle hole 2, a control chamber 4 for applying fuel pressure to the nozzle needle 3 in a valve closing direction, a high-pressure channel 5 for allowing fuel to flow into the control chamber 4, and a control chamber 4 includes a body 9 that forms a low-pressure flow path 6 for allowing fuel to flow out from the fuel 4, a control valve 10 that adjusts the fuel pressure in the control chamber 4, and an actuator 11 that drives the control valve 10.

The body 9 has a nozzle body 13 that accommodates the nozzle needle 3 so as to be movable in the axial direction.
The nozzle body 13 has a bottomed cylindrical shape that opens to the other axial end, and a substantially annular cylindrical nozzle chamber 14 is formed between the nozzle needle 3 and the nozzle body 13.
High pressure fuel is guided from the high pressure flow path 5 to the nozzle chamber 14, and the fuel pressure in the nozzle chamber 14 acts on the nozzle needle 3 in the valve opening direction.

  The nozzle body 13 is provided with a seat surface at the tip (bottom) of the nozzle needle 3 to which the seat portion provided at the tip of the nozzle needle 3 is attached and detached, and the nozzle hole 2 opens further on the tip side than the sheet surface. Yes. For this reason, when the seat portion is detached from the seat surface, the nozzle hole 14 and the nozzle chamber 14 are opened and closed, and fuel injection through the nozzle hole 2 is started or stopped.

The nozzle body 13 houses a cylinder 16 that slidably holds one end of the nozzle needle 3 in the axial direction.
The cylinder 16 is formed with a control chamber 4 which is formed on one end side of one end surface in the axial direction of the nozzle needle 3 and is closed by the inner peripheral surface of the cylinder 16 and one end surface in the axial direction of the nozzle needle 3. .

  The body 9 is also formed with a high-pressure channel 5 that communicates with the nozzle chamber 14 and supplies high-pressure fuel to the control chamber 4, and a low-pressure channel 6 that discharges fuel from the control chamber 4. .

  The control valve 10 has a three-way valve structure, and the valve body 19 accommodated in the valve chamber 18 is moved in the axial direction, so that the low pressure channel 6 and the control chamber 4 are interposed between the high pressure channel 5 and the control chamber 4. Open and close between.

The valve chamber 18 is always in communication with the control chamber 4. A first port 21 to which the high-pressure channel 5 is connected opens at the other axial end. Note that an IN orifice 22 is provided between the first port 21 and the high-pressure channel 5 to regulate the flow rate of fuel flowing into the control chamber 4 (see FIG. 1A).
Moreover, the 2nd port 24 to which the low voltage | pressure flow path 6 connects is opened in the axial direction one end side. Between the second port 24 and the low pressure flow path 6, there is provided an OUT orifice 26 for regulating the flow rate of the fuel flowing into the control chamber 4 (see FIG. 1 (b)).

A first seat (referred to as a lower seat 29) on which the valve body 19 is seated is formed around the opening of the first port 21 (see FIG. 1A).
A second seat (referred to as an upper seat 30) on which the valve body 19 is seated is formed around the opening of the second port 24.

The valve body 19 has a columnar shape, and a first seat portion 31 seated on the lower seat 29 is provided on the other axial end surface (plane) (see FIG. 1A). And the conical surface is provided in the axial direction one end part, and the 2nd sheet | seat part 32 seated on the upper sheet | seat 30 is provided in this conical surface (refer FIG.1 (b)).
Further, the valve body 19 is urged toward one end in the axial direction by a spring 34.

Accordingly, the first seat portion 31 is seated on the lower seat 29 by the movement of the valve body 19 toward the other end side in the axial direction, and the second seat portion 32 is seated on the upper seat 30 by the movement toward one end side in the axial direction.
That is, the valve body 19 is seated on the upper seat 30 from the other axial end side, and the valve body 19 is seated on the lower seat 29 from the one axial end side.

  In addition, the control valve 10 is formed on one end side in the axial direction of the upper seat 30, and flows out from the control chamber 4 to the low pressure passage 6 when the valve body 19 is separated from the upper seat 30. It has a flow path forming chamber 25 that forms part of the flow path.

The flow path forming chamber 25 is a cylindrical space that communicates with the opening of the second port 24 and is formed at one end in the axial direction of the opening of the second port 24, and this space is a low-pressure flow path via the OUT orifice 26. 6 is connected.
When the valve body 19 is separated from the upper seat 30, the fuel flows out from the control chamber 4 to the low pressure passage 6 through the second port 24, the passage formation chamber 25, and the OUT orifice 26. That is, the flow path forming chamber 25 forms a part of the outflow path for allowing fuel to flow out from the control chamber 4 to the low pressure flow path 6.

A rod holding portion 10a that slidably holds the rod 36 is formed on one end side in the axial direction of the flow path forming chamber 25. The sliding hole 10b of the rod holding portion 10a is formed in the flow path forming chamber 25. The diameter is smaller than that.
And the flow path formation chamber 25 is formed so that a diameter is small so that it may go to the sliding hole 10b side, and the ceiling surface 25a of the flow path formation chamber 25 is a taper surface.

The actuator 11 is, for example, a piezo actuator, and includes a piezo stack (not shown) in which a plurality of piezo elements are stacked in the axial direction, a rod 36 that moves in the axial direction when the extension of the piezo stack is transmitted.
The rod 36 contacts the valve body 19 from one end side in the axial direction, and pushes the valve body 19 into the other end side in the axial direction.

[Features of Example 1]
According to the injector 1 of the present embodiment, the rod 36 includes the sliding portion 36 a that is slidably supported by the rod holding portion 10 a formed on the body 9, and the flow path accommodated in the flow path forming chamber 25. And an inner rod portion 36b. And the flow path rod part 36b has the small diameter part 38 whose outer diameter is smaller than the sliding part 36a (refer FIG.1 (b)).

  In the present embodiment, the sliding portion 36a has a columnar shape, and the flow path rod portion 36b is provided in a cylindrical shape having a smaller diameter than the sliding portion 36a on the other axial end side of the sliding portion 36a. . That is, the entire flow path rod portion 36 b is a small diameter portion 38. In the present embodiment, the in-channel rod portion 36b has the same diameter from the other end in the axial direction to one end, and the tip (the other end surface in the axial direction) has a flat surface.

  The space on the outer periphery of the in-flow passage rod portion 36 b in the flow passage forming chamber 25 functions as an outflow passage through which fuel flows out from the control chamber 4 to the low pressure passage 6.

The rod 36 is slightly deformed when the valve body 19 is pushed in. However, since the opening of the second port 24 may be delayed if this deformation is too large, the rod 36 is allowed from the generated force and displacement of the actuator 11. The deformation amount (loss) of the rod 36 is determined.
And the diameter of the sliding part 36a and the flow-path rod part 36b is determined so that the deformation | transformation amount accept | permitted by this rod 36 whole may be satisfy | filled.

[Operation of Injector of Embodiment 1]
When the actuator 11 is driven by energizing the actuator 11 from the state shown in FIG. 1 (second port closed state) (the piezo stack extends) and the rod 36 pushes the valve body 19 toward the other end in the axial direction, The 2 port 24 is opened, and the fuel in the control chamber 4 flows out to the low pressure channel 6 through the channel forming chamber 25 and the OUT orifice 26.
As a result, the fuel pressure in the control chamber 4 is lowered, the nozzle needle 3 is displaced in the valve opening direction (one axial end side), the nozzle hole 2 is opened, and fuel is injected.

  When the energization of the actuator 11 is stopped, the force by which the rod 36 pushes the valve body 19 is released, so that the valve body 19 is displaced to one axial end side by the pressure of the high pressure fuel from the spring 34 and the first port 21. Then, the first port 21 is opened. As a result, the control chamber 4 and the high-pressure flow path 5 communicate with each other via the valve chamber 18, high-pressure fuel is supplied to the control chamber 4, and the pressure in the control chamber 4 increases. When the resultant force acting on the nozzle needle 3 in the axial direction increases in the valve closing direction, the nozzle needle 3 moves in the valve closing direction (on the other end side in the axial direction) and moves between the nozzle hole 2 and the nozzle chamber 19. Is closed and fuel injection stops.

[Effects of Example 1]
According to the injector 1 of the present embodiment, the rod 36 includes the sliding portion 36 a that is slidably supported by the rod holding portion 10 a formed on the body 9, and the flow path accommodated in the flow path forming chamber 25. And an inner rod portion 36b.
The flow path rod portion 36b has a small diameter portion 38 having an outer diameter smaller than that of the sliding portion 36a.

According to this, the design freedom of the flow path forming chamber 25 that forms a part of the outflow flow path can be achieved by making the rod 36b in the flow path small in diameter while mainly securing the strength of the rod 36 in the sliding part 36a. The degree can be secured.
According to this, the design freedom degree of the flow path formation chamber 25 can be raised without incurring cost, and desired injection characteristics can be obtained.

[Example 2]
The configuration of the injector 1 according to the second embodiment will be described with reference to FIG. 2A with a focus on differences from the first embodiment.
In the first embodiment, the flow path rod portion 36b has the same diameter from the other end in the axial direction to the other end. However, in this embodiment, the flow path rod portion 36b is in the axial direction or the like that contacts the valve body 19. The outer diameter of the end portion 39 is larger than the one end side in the axial direction.

According to this, in addition to the effect of the first embodiment, the rigidity of the portion in contact with the valve body 19 can be increased.
The outer diameter of the other axial end portion 39 may be smaller than the outer diameter of the sliding portion 36a, may be equal to the sliding portion 36a, or larger than the outer diameter of the sliding portion 36a. Also good.

Example 3
The structure of the injector 1 of Example 3 is demonstrated using FIG.2 (b)-(d) centering on a different point from Example 1. FIG.
In the first embodiment, the in-flow passage rod portion 36b has the same diameter from the other end in the axial direction to one end, but in this embodiment, the in-flow passage rod portion 36b has a diameter toward the other end in the axial direction. Is getting smaller.

  That is, for example, as shown in FIG. 2B, the flow path rod portion 36b is made smaller in diameter than the sliding portion 36a via the stepped portion 40, and becomes smoother toward the other end side in the axial direction. The diameter may be reduced and the tip may be spherical.

  Moreover, as shown in FIG.2 (c), the flow-path rod part 36b is made smaller diameter than the sliding part 36a via the step part 40, and becomes a taper shape toward the other end side of an axial direction. The diameter may be reduced and the tip may be flat.

  As shown in FIG. 2D, the flow path rod portion 36b is tapered from the outer diameter of the sliding portion 36a without the stepped portion 40, and the tip is flat. Also good.

[Modification]
According to the injectors 1 of the first to third embodiments, the actuator 11 uses the extension of the piezo stack, but is not limited thereto. For example, an actuator using a magnetic attraction force by an electromagnetic solenoid may be used.

  Moreover, according to the injector 1 of Examples 1-3, although the control valve 10 was a three-way valve, a two-way valve may be sufficient.

DESCRIPTION OF SYMBOLS 1 Injector 2 Injection hole 3 Nozzle needle 4 Control chamber 5 High pressure flow path 6 Low pressure flow path 9 Body 10 Control valve 11 Actuator 19 Valve body 25 Flow path formation chamber 30 Upper sheet 36 Rod 36a Sliding part 36b Flow path rod part 39 The other axial end (of the rod in the channel)

Claims (3)

A nozzle needle (3) for opening and closing the nozzle hole (2);
A control chamber (4) for applying fuel pressure to the nozzle needle (3) in the valve closing direction;
A control valve (10) having a valve body (19) for opening and closing communication between the low pressure flow path (6) and the control chamber (4), and adjusting a fuel pressure in the control chamber (4);
An injector comprising an actuator (11) for driving the control valve (10),
The actuator (11) has a rod (36) that abuts from one end side in the axial direction of the valve body (19) of the control valve (10) and pushes the valve body (19) into the other end side in the axial direction. ,
The control valve (10)
An upper seat (30) from which the valve body (19) is seated and separated from the other axial end;
The upper seat (30) is formed on one end side in the axial direction, and when the valve body (19) is separated from the upper seat (30), the control chamber (4) and the low pressure channel (6 And a flow path forming chamber (25) that forms part of an outflow flow path for letting fuel flow out to
The rod (36) is formed on a sliding portion (36a) slidably supported by a predetermined body, and on the other end side in the axial direction of the sliding portion (36a), and the flow path forming chamber ( 25) a flow-path rod portion (36b) accommodated in
The injector, wherein the flow path rod portion (36b) has a small diameter portion (38) having an outer diameter smaller than that of the sliding portion (36a). The injector according to claim 1, wherein
The injector, wherein the flow path rod portion (36b) has an outer diameter of the other axial end portion (39) that contacts the valve body (19) larger than that of one axial end side. The injector according to claim 1, wherein
The injector, wherein the rod portion (36b) in the flow path is smaller in diameter than the sliding portion (36a) and decreases in diameter toward the other end side in the axial direction.

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