JP5246149B2 - 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, an injector is known in which a voltage is applied to a laminated body of piezoelectric elements to extend the laminated body in the axial direction, thereby driving a valve body to open a nozzle hole (hereinafter referred to as piezoelectric). An injector that opens when a voltage is applied to a stack of elements is sometimes referred to as a piezo injector).

In the conventional piezo injector 100, an annular adhesive layer (not shown) is formed by applying an electrically insulating adhesive to the outer peripheral surface of the laminate 101 from the viewpoint of avoiding fuel adhesion to the piezoelectric element and electrical insulation. ), And the outer peripheral side of the adhesive layer is covered with an insulating material (not shown), and a SUS cover 103 is arranged so as to form a cavity 102 on the outer peripheral side of the insulating material (see FIG. 4).

The bellows 104 is connected to one end of the SUS cover 103 and the SUS cover 103 is connected to one end of the SUS cover 103 in order to transmit the extension force of the laminated body 101 to other members while ensuring fuel adhesion avoidance and electrical insulation properties to the piezoelectric element. Is sealed at one end (see, for example, Patent Document 1).

  However, when the bellows 104 expands in the axial direction, the diameter of the bellows 104 decreases and the spring constant in the axial direction increases. For this reason, as the laminated body 101 extends, the resistance of the bellows 104 to the elongation of the laminated body 101 increases, and the elongation force of the laminated body 101 becomes difficult to be transmitted.

JP 2002-202023 A

  The present invention has been made in order to solve the above-described problems. The purpose of the present invention is to prevent the bellows from acting as a resistance against the extension of the laminate in the piezoelectric injector even if the laminate of the piezoelectric elements is extended. It is in suppressing.

[Means of Claim 1]
The injector according to claim 1 applies a voltage to the laminated body of piezoelectric elements to extend the laminated body in the axial direction, thereby driving the valve body to open the injection hole.
In addition, the injector includes a bellows assembly in which two bellows having different diameters are coaxially arranged and the two bellows are connected by an annular connecting member. The two bellows are connected to each other by a connecting member so that the inflow and outflow of fluid is blocked between the outer peripheral side and the inner peripheral side in the radial direction, and the laminated body is attached to the inner peripheral side of the bellows assembly. It is accommodated coaxially with the solid.

Furthermore, the one end and the other end in the axial direction of the bellows assembly are respectively blocked by the one end side member and the other end side member that support the one end and the other end in the axial direction of the laminated body, and the flow of fluid is blocked.
The two bellows are both less rigid in the axial direction than in the radial direction.

Thereby, the inner volume of the bellows assembly does not change no matter how the laminated body expands and contracts in the axial direction. That is, since the two bellows are both less rigid in the axial direction than in the radial direction, the amount of expansion and contraction in the radial direction is small even when the stack is expanded and contracted in the axial direction. For this reason, if the laminated body is elongated and the bellows assembly is lengthened in the axial direction, the small-diameter bellows is elongated in the axial direction, and the small-diameter bellows is elongated, thereby extending the region surrounded by the small-diameter bellows. Volume increases. The volume increase in the region surrounded by the small diameter bellows is absorbed by the large diameter bellows being shortened in the axial direction.

That is, when the laminated body is elongated, in the bellows assembly, the small diameter bellows is expanded and the large diameter bellows is shortened. As a result, even if the small-diameter bellows is extended to increase the resistance to the extension of the laminate, the large-diameter bellows is reduced in the axial direction to reduce the resistance to the extension of the laminate. For example, as compared with a single bellows, it can suppress acting as a resistance to the elongation of the laminate.
As described above, in the piezo injector, it is possible to suppress the bellows from acting as a resistance to the extension of the multilayer body even if the multilayer body of the piezoelectric elements is elongated.

[Means of claim 2]
According to the injector of the second aspect, the annular bodies are respectively attached to the inner peripheral sides of the two bellows to increase the radial rigidity.
As a result, the two bellows are more difficult to change in diameter, so that the bellows having a small diameter and a large diameter can be expanded or shortened without changing the diameter reliably according to the expansion of the laminate. To come.

[Means of claim 3]
According to the injector of the third aspect, the connecting member is supported by the predetermined support member so as to be slidable in the axial direction.
Thereby, the expansion-contraction operation | movement of each bellows can be stabilized regarding an axial direction.

It is a whole block diagram of an injector (Example 1). (A) is explanatory drawing which shows the piezoelectric actuator before expansion | extension, (b) is explanatory drawing which shows the piezoelectric actuator after expansion | extension (Example 1). (Example 2) which is explanatory drawing which shows a piezoelectric actuator. (A) is explanatory drawing which shows the principal part of the piezo injector before expansion | extension, (b) is explanatory drawing which shows the principal part of the piezo injector after expansion | extension (conventional example).

The injector of Embodiment 1 applies a voltage to the laminated body of piezoelectric elements to extend the laminated body in the axial direction, thereby driving the valve body to open the injection hole.
In addition, the injector includes a bellows assembly in which two bellows having different diameters are coaxially arranged and the two bellows are connected by an annular connecting member. The two bellows are connected to each other by a connecting member so that the inflow and outflow of fluid is blocked between the outer peripheral side and the inner peripheral side in the radial direction, and the laminated body is attached to the inner peripheral side of the bellows assembly. It is accommodated coaxially with the solid.

Furthermore, the one end and the other end in the axial direction of the bellows assembly are respectively blocked by the one end side member and the other end side member that support the one end and the other end in the axial direction of the laminated body, and the flow of fluid is blocked.
The two bellows are both less rigid in the axial direction than in the radial direction.

According to the injector of the second embodiment, the annular bodies are respectively attached to the inner peripheral sides of the two bellows to increase the radial rigidity.
The connecting member is supported by a predetermined supporting member so as to be slidable in the axial direction.

[Configuration of Example 1]
The structure of the injector 1 of Example 1 is demonstrated using FIG.
The injector 1 is mounted on each cylinder of an engine (not shown), for example, and injects fuel directly into a combustion chamber (not shown). A voltage is applied to the piezoelectric element laminate 2. By extending the laminated body 2 in the axial direction, the valve body 3 is driven to open the injection hole 4.

The injector 1 transmits to the nozzle unit 6 a nozzle unit 6 that injects fuel, a piezoelectric actuator 7 that has a stacked body 2 and drives the valve body 3 of the nozzle unit 6, and a driving force generated by the piezoelectric actuator 7. For example, receiving high-pressure fuel from the common rail and guiding the received fuel to the nozzle hole 4 at the tip through a fuel flow passage formed therein to drive the valve body 3. Is ejected through the nozzle hole 4.

The nozzle part 6 is a cylindrical body that supports a valve body 3 that opens and closes the nozzle hole 4, a valve body 9 having the nozzle hole 4 at the tip, and a sliding shaft part 10 of the valve body 3 so as to be slidable in the axial direction. A first internal body 11, a spring 12 that biases the valve body 3 toward the valve closing side, and a second internal body that forms a spring chamber 13 that seals the rear end side of the first internal body 11 and accommodates the spring 12. 14.

Here, the valve body 9 accommodates the tip of the valve body 3 so as to be slidable in the axial direction, thereby forming a nozzle chamber 18 for guiding fuel to the nozzle hole 4 between the valve body 3 and the valve body 9. The spring chamber 13 constitutes a part of a fuel flow path for guiding high-pressure fuel received from the common rail toward the nozzle hole 4, and the spring chamber 13 is a fuel passage 19 provided in the second inner body 14. Accept high pressure fuel through. The spring chamber 13 and the nozzle chamber 18 communicate with each other via a fuel passage 20 provided in the valve body 3.
With the above configuration, the high-pressure fuel received from the common rail is guided to the nozzle hole 4.

In addition, the first internal body 11 forms a control chamber 23 between the valve body 3 for applying fuel pressure to the valve body 3 on the valve opening side. Then, when the fuel pressure in the control chamber 23 increases or decreases in accordance with the operation of the piezo actuator 7, the valve body 3 opens or closes.

The piezo actuator 7 includes a multilayer body 2 of piezoelectric elements and a bellows assembly 24 that houses the multilayer body 2.
The bellows assembly 24 coaxially arranges two bellows having different diameters (hereinafter, the larger diameter is referred to as a large diameter bellows 26 and the smaller diameter is referred to as a small diameter bellows 27), and has a large diameter and a small diameter. The bellows 26 and 27 are connected by an annular connecting member 28.

The large-diameter and small-diameter bellows 26 and 27 are connected by a connecting member 28 so that the inflow and outflow of fuel is blocked between the outer peripheral side and the inner peripheral side with respect to the radial direction. The bellows assembly 24 is accommodated coaxially on the inner peripheral side. Further, the front end and the rear end of the bellows assembly 24 are blocked by a front end side member 29 and a rear end side member 30 that support the front end and the rear end of the laminated body 2, respectively, so that the inflow and outflow of fuel are blocked. And both large diameter and small diameter bellows 26 and 27 have lower rigidity in the axial direction than in the radial direction.

The driving force transmission unit 8 forms a pressure chamber 34 between the piston 33 abutted by the tip of the piezo actuator 7 and moving to the tip side, and the piston 33 slidably and the second inner body 14. A cylindrical third inner body 35 and a spring 36 for urging the piston 33 toward the rear end. Here, high pressure fuel received from the common rail is supplied to the pressure chamber 34 via the check valve 37, and the pressure chamber 34 and the control chamber 23 pass through the first and second inner bodies 11 and 14. The passage 38 communicates.

Thereby, when the laminated body 2 extends and moves the piston 33 to the tip side, the pressure chamber 34 is compressed and the fuel pressure in the control chamber 23 rises. For this reason, the valve body 3 is driven to the valve opening side, the nozzle hole 4 is opened, and fuel injection is started. When the stacked body 2 is shortened and the piston 33 moves to the rear end side, the pressure chamber 34 is expanded and the fuel pressure in the control chamber 23 is reduced. For this reason, the valve body 3 is driven to the valve closing side, the injection hole 4 is closed, and fuel injection stops.
In addition, the voltage application start and voltage application stop with respect to the laminated body 2 are performed according to a command from a predetermined electronic control device mounted on the vehicle.

[Effects of Example 1]
The effect of the injector 1 of Example 1 is demonstrated using FIG.
When the laminate 2 is extended in the axial direction by applying a voltage, in the bellows assembly 24, the large-diameter bellows 26 is shortened and the small-diameter bellows 27 is extended so that the internal volume of the bellows assembly 24 does not change. That is, both the large-diameter and small-diameter bellows 26 and 27 are less rigid in the axial direction than in the radial direction, so that the amount of expansion and contraction in the radial direction is small even when the laminate 2 expands and contracts in the axial direction.

For this reason, if the laminated body 2 extends and the bellows assembly 24 becomes longer in the axial direction, the small-diameter bellows 27 expands in the axial direction, and the small-diameter bellows 27 extends, whereby the volume of the region surrounded by the small-diameter bellows 27 is increased. Will increase. The volume increase in the region surrounded by the small diameter bellows 27 is absorbed by the large diameter bellows 26 being shortened in the axial direction.

That is, when the laminated body 2 is extended, in the bellows assembly 24, the small-diameter bellows 27 is extended and the large-diameter bellows 26 is shortened. As a result, even if the small-diameter bellows 27 is extended to increase the resistance to the extension of the laminated body 2, the large-diameter bellows 26 is reduced in the axial direction to reduce the resistance to the extension of the laminated body 2. According to this, it can suppress acting as resistance with respect to the expansion | extension of the laminated body 2 compared with a single bellows.
As described above, by adopting the bellows assembly 24 in the injector 1, it is possible to suppress resistance to the extension of the stacked body 2 compared to the case of using a single bellows.

According to the injector 1 of the second embodiment, as shown in FIG. 3, the annular bodies 41 are attached to the inner peripheral sides of the large-diameter and small-diameter bellows 26 and 27, respectively, and the radial rigidity is enhanced.
As a result, the diameters of the large and small diameter bellows 26 and 27 are more difficult to change. Therefore, the large diameter and small diameter bellows 26 and 27 do not change the diameter reliably according to the extension of the laminate 2. , It will stretch and shorten.
The connecting member 28 is supported on the inner peripheral side of the piston 33 so as to be slidable in the axial direction. Thereby, the expansion-contraction operation | movement of the large diameter and small diameter bellows 26 and 27 can be stabilized regarding an axial direction.

[Modification]
The mode of the injector 1 is not limited to the first and second embodiments, and various modifications can be considered. For example, although the injectors 1 of the first and second embodiments inject fuel directly into the combustion chamber, the injector 1 may be mounted on the intake manifold and injected into the intake port.

DESCRIPTION OF SYMBOLS 1 Injector 2 Laminated body 3 Valve body 4 Injection hole 24 Bellows assembly 26 Large diameter bellows (two bellows)
27 Small-diameter bellows (two bellows)
28 connecting member 29 tip side member (one end side member)
30 Rear end side member (other end side member)
41 toroid

Claims (3)

In an injector that opens a nozzle hole by driving a valve body by applying a voltage to a laminate of piezoelectric elements and extending the laminate in the axial direction.
A bellows assembly in which two bellows having different diameters are coaxially arranged, and the two bellows are connected by an annular connecting member,
The two bellows are connected by the connecting member so that fluid inflow and outflow is blocked between the outer peripheral side and the inner peripheral side in the radial direction,
The laminate is accommodated coaxially with the bellows assembly on the inner peripheral side of the bellows assembly,
One end and the other end in the axial direction of the bellows assembly are respectively blocked by one end side member and the other end side member that support the one end and the other end in the axial direction of the laminate, and the flow of fluid is blocked.
Both of the two bellows are less rigid in the axial direction than in the radial direction. The injector according to claim 1, wherein
An injector characterized in that an annular body is attached to each of the inner peripheral sides of the two bellows to increase radial rigidity. Injector according to claim 1 or claim 2,
The injector is characterized in that the connecting member is supported by a predetermined support member so as to be slidable in the axial direction.

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