Fuel injection device

An injector includes a nozzle portion to inject fluid, a coil to generate a driving force to open and close the nozzle portion, and a molded resin that seals the coil. A cooling jacket has a flow path to cause cooling fluid to flow therethrough. The cooling jacket houses the injector and has an opening in an end opposite to the nozzle portion. A sealing material is filled in a space between the cooling jacket and the molded resin.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of priority from Japanese Patent Application No. 2019-113848 filed on Jun. 19, 2019. The entire disclosures of all of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a fuel injection device.

BACKGROUND

Conventionally, a known fluid injection device is used in an internal combustion engine system.

SUMMARY

According to an aspect of the present disclosure, a fluid injection device includes an injector and a cooling jacket.

DETAILED DESCRIPTION

Hereinbelow, examples of the present disclosure will be described.

According to an example of the present disclosure, an injector is used in a high-temperature environment. The injector is housed inside a cooling jacket and is cooled with a cooling fluid flowing through the cooling jacket. According to an example of the present disclosure, a fluid injection device is configured to inject a reducing agent from an injector into an exhaust pipe of an engine. In this example, the fluid injection device includes the injector and a housing. The housing houses the injector and further serves as a cooling jacket that enables a cooling fluid to flow therethrough for cooling the injector.

In an example of the present disclosure, the housing includes: a pot-shaped main body that houses the injector; a cover that closes an opening of the main body to restrict foreign matter from entering the inside of the main body; and an internal housing that enables a cooling fluid to flow. Further, in this example, the cover supports a pipe, which is for supplying a reducing agent to the injector, and a socket, which is for taking out a harness to be electrically connected to an electric terminal of the injector.

It is noted that, the inventor found out, as a result of detailed studies, an issue of the above examples. Specifically, in the examples, the number of components of a fluid injection device may increase in order to embody various functions to close the opening of the housing, to support the socket and the pipe to enable the harness to be taken out of the injector to the outside, and further to enable a cooling fluid to flow therethrough. In the case where the number of components increases, the fluid injection device may become large in size.

According to another example of the present disclosure, a fluid injection device comprises an injector that includes: a nozzle portion configured to inject fluid; a coil configured to generate a driving force to drive the nozzle portion to open and close the nozzle portion; and a molded resin that seals the coil.

The fluid injection device further comprises a cooling jacket that has a flow path configured to cause cooling fluid to flow therethrough, that houses the injector, and that has an opening in an end opposite to the nozzle portion. The fluid injection device further comprises a sealing material that is filled in a space between the cooling jacket and the molded resin.

According to this configuration, the injector is supported by the sealing material filled in the space between the cooling jacket and the molded resin. Furthermore, even a configuration in which the opening at the end of the cooling jacket opposite to the nozzle is not enclosed with a cover but is open, the components of the injector encapsulated with the sealing material can be protected from exposure to the environment on the opening side of the cooling jacket.

In this way, the sealing member may have various functions required for the fluid injection device. Therefore, the number of components of the fluid injection device may be reduced. Thus, the configuration may enable to downsize the fluid injection device.

Hereinbelow, embodiments of the present disclosure will be described with reference to the drawings.

1. First Embodiment

A fluid injection device2shown inFIG. 1includes a cooling jacket20, an injector30, and a sealing material50. The fluid injection device2is installed, for example, upstream of an SCR catalyst in an exhaust pipe of an internal combustion engine to inject ammonia as a reducing agent into an exhaust passage upstream of the SCR catalyst. SCR is an abbreviation of selective catalytic reduction.

The cooling jacket20includes a tubular outer jacket22and a tubular inner jacket24that is smaller in diameter than the outer jacket22. A space between the outer jacket22and the inner jacket24forms a flow path200that is ring-shaped in cross section for causing cooling water as a cooling fluid to flow therethrough.

The outer jacket22has a cooling water inlet202and a cooling water outlet204. The cooling water inlet202is formed on one end side of the outer jacket22in the axial direction that is on the side of a nozzle portion36of the injector30. The cooling water outlet204is formed on the other end side of the outer jacket22opposite to the nozzle portion36. The cooling jacket20has an opening at the end opposite to the nozzle portion36of the injector30.

A cooling water supplied to the cooling water inlet202is fed through the flow path200and is discharged from the cooling water outlet204. The injector30housed on the radially inside of the inner jacket24is cooled with the cooling water flowing through the flow path200.

The injector30includes a valve body32, the nozzle portion36, a coil40, harnesses42to be described later, and a molded resin46. One end of the valve body32has an inflow port34to which urea water is supplied. The other end of the valve body32is equipped with an injection hole plate38of the nozzle portion36by welding or the like.

The injection hole plate38has an injection hole for injecting a urea water that flows from the inflow port34. A nozzle needle (not shown) of the nozzle portion36moves back and forth thereby to open and close nozzle holes of the injection hole plate38.

The coil40is an electromagnetic drive unit that generates a driving force to drive the nozzle needle to move back and forth thereby to open and close the nozzle holes. The harnesses42shown inFIGS. 2 and 3are to supply electric power to the coil40. The two harnesses42are supported by a support member44and are taken out of the molded resin46. Note that the harnesses42is not shown in the sectional view ofFIG. 1.

The molded resin46covers the periphery of the coil40to seal the coil40and to fix the coil40. As shown inFIGS. 1 to 3, the outer peripheral surface of the molded resin46has a flat portion48partially in the circumferential direction. The flat portion48is recessed from the periphery toward the axial center and extends in the axial direction. The flat portion48may be formed outside an angular range θ in the circumferential direction about a center axis300of the injector30to include the two harnesses42. For example, the angle range θ is 25°. In the first embodiment, the flat portion48is formed on the opposite side of the two harnesses42in the radial direction.

The sealing material50is filled into a space between the inner jacket24and the molded resin46through an opening of the cooling jacket20. The opening of the cooling jacket20is formed in the end of the cooling jacket20opposite to the nozzle portion36of the injector30. The sealing material50covers the molded resin46and supports the injector30. As described above, the opening in the end of the cooling jacket20, which is opposite to the nozzle portion36of the injector30, is open. Therefore, the sealing material50is exposed to the environment on the side of the opening of the cooling jacket20.

The sealing material50is a compound formed by mixing metal powder or metal oxide powder, which is high in thermal conductivity, into a resin material, which has a thermosetting property and flexibility. The resin, which has a thermosetting property and flexibility is, for example, urethane resin, silicon resin, epoxy resin, or the like. The metal powder or metal oxide powder, which is high in thermal conductivity is, for example, alumina.

The sealing material50is filled at a position above the space between the flat portion48and the inner jacket24into the space. Herein, as described above, the flat portion48is recessed toward the center relative to the remaining portion of the molded resin46in the circumferential direction. Therefore, the distance between the flat portion48and the inner peripheral surface of the inner jacket24in the radial direction is larger than the distance between the outer peripheral surface of the remaining portion of the molded resin46other than the flat portion48in the circumferential direction and the inner peripheral surface of the inner jacket24.

That is, the space between the flat portion48and the inner jacket24forms an enlarged portion210in which the distance in the radial direction is larger than the distance in the radial direction in the other space. Therefore, a flow path resistance, which is a resistance against fluid flow, in the space between the flat portion48and the inner jacket24is smaller than the flow path resistance in the space between the outer peripheral surface of the remaining portion of the molded resin46, which is other than the flat portion48, and the inner jacket24.

Fluid flows more easily in a space in which the flow path resistance is small compared with a space in which the flow path resistance is large. Therefore, the sealing material50, which is filled from the filling position above the enlarged portion210directly reaches the bottom of the space between the flat portion48and the inner jacket24underneath the filling position more fast than reaching the space on the radially opposite side of the filling position after flowing along the circumferential direction. Subsequently, the sealing material50that has flowed into the space between the flat portion48and the inner jacket24further flows into the remaining space in the circumferential direction and upward from the underneath.

The first embodiment described above produces the following effects.

(1a) The flow path resistance in the space between the flat portion48and the inner jacket24is smaller than the flow path resistance in the other remaining space. Therefore, the sealing material50reaches the bottom portion faster than the other remaining space, without trapping air bubbles in the space between the flat portion48and the inner jacket24.

The sealing material50flowing into the space between the flat portion48and the inner jacket24flows upward from the bottom to push up air in the other remaining space before the sealing material50flowing in the circumferential direction encapsulates the upper portion of the other remaining space. In this way, the sealing material50excludes air from the space between the molded resin46and the inner jacket24, thereby to enable to restrict air bubbles from being trapped in the sealing material50that is filled.

(1b) The sealing material50filled in the space between the cooling jacket20and the molded resin46supports the injector30. Furthermore, the sealing material50covers at least the molded resin46. Therefore, even in the configuration where the opening in the end of the cooling jacket20on the opposite side to the nozzle portion36is open, the sealing material50enables to protect the injector30, which is embedded with the sealing material50, from exposure to the environment on the side of the opening of the cooling jacket20.

As described above, the sealing material50produces various functions required for the fluid injection device2. Therefore, the number of components of the fluid injection device2can be reduced as much as possible. In this way, the configuration enables to downsize the fluid injection device2.

(1c) The resin material of the sealing material50has a thermosetting property and flexibility. Therefore, even in a case where the sealing material50repeats expansion and contraction due to change in the surrounding temperature, the sealing material50enables to adapt to the expansion and contraction without damage such as cracking while maintaining its hardness in a high-temperature environment.

(1d) The resin material of the sealing material50is mixed with metal powder or metal oxide powder that has high thermal conductivity. Therefore, the injector30can be efficiently cooled by the cooling water flowing through the cooling jacket20.

2. Second Embodiment

2-1. Difference from First Embodiment

The fundamental configuration of the second embodiment is similar to that of the first embodiment. Therefore, the difference therebetween will be described below. The same reference numerals as in the first embodiment denote the same components, and reference is made to the preceding description.

In the fluid injection device2of the first embodiment described above, the flat portion48is formed in the part of the molded resin46in the circumferential direction. In this way, the first embodiment enables to reduce the flow path resistance in the space between the flat portion48and the inner jacket24in the space compared with the flow path resistance in the other remaining space. The first embodiment, in this way, raises the difference in flow path resistance in the space filled with the sealing material50.

To the contrary, in a fluid injection device4according to the second embodiment shown inFIGS. 4 and 5, an inner jacket62of a cooling jacket60has a recess portion64partially in the circumferential direction. The inner peripheral surface of the inner jacket62is dented in the recess portion64outward in the radial direction. In an injector70of the second embodiment, the outer diameter of a molded resin72is constant. It is noted that, inFIG. 15, illustration of harnesses42is omitted.

The second embodiment is different from the first embodiment in this configuration, in which the distance in the radial direction between the recess portion64of the inner jacket62and the molded resin72in a predetermined region in the circumferential direction is larger than the distance in the radial direction between the portion of the inner jacket62other than the recess portion64and the molded resin72in a predetermined region in the circumferential direction.

In the second embodiment, the enlarged portion210is formed in which the distance in the radial direction between the recess portion64of the inner jacket62and the molded resin72in the predetermined region in the circumferential direction is larger than the distance in the radial direction between the portion of the inner jacket62other than the recess portion64and the molded resin72in the predetermined region in the circumferential direction.

In this configuration of the second embodiment, the flow path resistance in the space between the recess portion64and the molded resin72is smaller than the flow path resistance in the space between the portion of the inner jacket62other than the recess portion64and the molded resin72.

The second embodiment described above produces the following effects in addition to the effects (1b) to (1d) of the first embodiment described above.

(2a) The flow path resistance in the space between the recess portion64and the molded resin72is smaller than the flow path resistance in the space formed between the portion of the inner jacket62other than the recess portion64and the molded resin72. Therefore, the space between the recess portion64and the molded resin72is filled with the sealing material50to the bottom faster than the other space without trapping air bubbles therein.

The sealing material50that has flowed into the space between the recess portion64and the molded resin72flows upward from the bottom to push air in the other space upward before the upper portion of the other space is encapsulated with the sealing material50that flows in the circumferential direction. In this way, the sealing material50excludes air from the space between the molded resin46and the inner jacket62, thereby to enable to restrict air bubbles from being trapped in the sealing material50that is filled.

3-1. Difference from Second Embodiment

The fundamental configuration of the third embodiment is similar to that of the second embodiment. Therefore, the difference therebetween will be described below. The same reference numerals as in the first and second embodiments denote the same components, and reference is made to the preceding description.

In the fluid injection device4of the second embodiment described above, the recess portion64is formed in the part of the inner jacket62of the cooling jacket60in which the inner circumferential surface is dented outward in the radial direction in the predetermined region in the circumferential direction. In this way, the second embodiment reduces the flow path resistance in the space between the recess portion64and the molded resin72compared with the flow path resistance in the space between the portion of the inner jacket62other than the recess portion64and the molded resin72.

To the contrary, in a fluid injection device6of the third embodiment shown inFIGS. 6 and 7, a resistance adjusting member84having a C-shaped cross section is resiliently fitted to the inner peripheral surface of the inner jacket24. The resistance adjusting member84may be formed of metal or resin. The resistance adjusting member84is a part of the inner jacket24and forms an inner peripheral surface of the inner jacket24. The outer diameter of a molded resin82of an injector80is constant. InFIG. 7, illustration of the harnesses42is omitted.

In this configuration of the third embodiment, the space between the portion of the inner jacket24, in which the resistance adjusting member84does not reside, and the molded resin82is larger than the space between the resistance adjusting member84and the molded resin82. The third embodiment is different from the second embodiment in this configuration in which the flow path resistance in the space between the portion of the inner jacket24, in which the resistance adjusting member84does not reside, and the molded resin82is smaller than the flow path resistance in the space between the resistance adjusting member84and the molded resin82.

The third embodiment forms the enlarged portion210, in which the space between the portion of the inner jacket24, in which the resistance adjusting member84does not reside, and the molded resin82is larger than the space between the resistance adjusting member84and the molded resin82.

The third embodiment described above produces the following effects in addition to the effects (1b) to (1d) of the first embodiment described above.

(3a) The flow path resistance in the space between the portion of the inner jacket24, in which the resistance adjusting member84does not arise, and the molded resin82is smaller than the flow path resistance in the space between the resistance adjusting member84and the molded resin82. Therefore, the space between the portion of the inner jacket24, in which the resistance adjusting member84does not arise, and the molded resin82is filled with the sealing material50to the bottom faster than the other remaining space without trapping air bubbles therein.

The sealing material50that has flowed into the space between the portion of the inner jacket24, in which the resistance adjusting member84does not arise, and the molded resin82flows upward from the bottom to push up air in the other remaining space before the upper portion of the other remaining space is encapsulated with the sealing material50flowing in the circumferential direction. In this way, air is extruded from the space between the molded resin82and the inner jacket24and from the space between the molded resin82and the resistance adjusting member84, thereby to restrict air bubbles from being trapped in the sealing material50that is filled.

4-1. Difference from First Embodiment

The fundamental configuration of the fourth embodiment is similar to that of the first embodiment. Therefore, the difference therebetween will be described below. The same reference numerals as in the first embodiment denote the same components, and reference is made to the preceding description.

The fluid injection device2of the first embodiment described above raises the difference in the flow path resistance in the space between the molded resin46and the inner jacket24, thereby to enable to fill the sealing material50faster to the bottom of the space where the flow path resistance is smaller than the other remaining space.

To the contrary, in a fluid injection device8of the fourth embodiment shown inFIGS. 8 and 9, the outer diameter of a molded resin92of an injector90is constant. Therefore, the fourth embodiment differs from the first embodiment in that the flow path resistance of the space between the molded resin92and the inner jacket24is constant. InFIG. 7, illustration of the harnesses42is omitted.

It is noted that, in the fourth embodiment, a through hole94that penetrates the molded resin92in the axial direction is formed at least at one position in the circumferential direction of the molded resin92. At the circumferential position where the through hole94is formed, the sealing material50flows into the bottom of the inner jacket24through the through hole94in addition to the space between the molded resin92and the inner jacket24.

Therefore, at the circumferential position where the through hole94is formed, the sealing material50flows to the bottom of the inner jacket24faster than at the other remaining circumferential positions.

The fourth embodiment described above produces the following effects in addition to the effects (1b) to (1d) of the first embodiment described above.

(4a) At the circumferential position where the through hole94is formed, the sealing material50flows into the bottom of the inner jacket24faster than at the other remaining circumferential positions, and therefore, the bottom is filled with the sealing material50, without trapping and sealing air bubbles.

The sealing material50that has flowed to the bottom at the circumferential position where the through hole94is formed flows upward from the bottom to push up air in the other remaining space before the upper portion in the other remaining space is encapsulated with the sealing material50that flows in the circumferential direction. In this way, the sealing material50excludes air from the space between the molded resin92and the inner jacket24, thereby to enable to restrict air bubbles from being trapped in the sealing material50that is filled.

5-1. Difference from Fourth Embodiment

The fundamental configuration of the fifth embodiment is similar to that of the fourth embodiment. Therefore, the difference therebetween will be described below. The same reference numerals as in the fourth embodiment denote the same components, and reference is made to the preceding description.

A fluid injection device10according to the fifth embodiment shown inFIG. 10is the same as the fluid injection device8of the fourth embodiment in that the through hole94that penetrates the molded resin92in the axial direction is formed at least at the one position in the circumferential direction of the molded resin92of the injector90.

In the fifth embodiment, a cooling jacket100further includes a connection pipe102at the same circumferential position as the through hole94. The connection pipe102connects the outer jacket22with the inner jacket24. The connection pipe102forms a communication flow path104at a position corresponding to the bottom of the space between the molded resin92and the inner jacket24. The communication flow path104forms the communication flow path104that communicates the space on the radially inner side of the inner jacket24with the space on the radially outer side of the outer jacket22. More specifically, the communication flow path104may be formed at the position corresponding to the filling position in the circumferential direction and/or the radial direction.

This configuration enables air that is pushed by the sealing material50flowing into the bottom of the inner jacket24through the through hole94is discharged to the outside of the outer jacket22through the connection pipe102.

The fifth embodiment described above enables to produce the following effects in addition to the effects (1b) to (1d) of the first embodiment and the effect (4a) of the fourth embodiment.

(5a) The air pushed by the sealing material50flowing into the bottom of the inner jacket24through the through hole94is discharged to the outside of the outer jacket22through the connection pipe102, such that air is discharged to the outside of the inner jacket24. In this way, this configuration enables to fill the sealing material50in the bottom of the inner jacket24without trapping air bubbles.

6. Other Embodiments

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above, and various modifications can be made to implement the present disclosure.

(6a) In the above embodiment, the description has been given of the device that injects urea water into the exhaust passage of the internal combustion engine at the position upstream of the SCR catalyst as the fluid injection device that cools the injector with the cooling water flowing through the cooling jacket. The fluid sprayed with the injector is not limited to urea water. For example, the injector may inject fuel into an exhaust passage upstream of a DOC. DOC is an abbreviation for a diesel oxygen catalyst.

(6b) The fluid injection device is not limited to being used in an internal combustion engine and may be used in various fields as long as the fluid injection device is used in a high-temperature environment to cool an injector with a cooling fluid flowing through a cooling jacket.

(6c) The first embodiment and the second embodiment may be combined. Specifically, the recess portion64may be formed in the inner jacket62in the predetermined region in the circumferential direction that faces the flat portion48of the molded resin46.

(6d) In the first embodiment, the inner jacket24and the outer jacket22at the bottom of the enlarged portion210may be communicated through the connection pipe102described in the fourth embodiment.

(6e) The distance in the radial direction between the molded resin and the inner jacket may be constant in the entirety of the circumference in a configuration in which the end of the cooling jacket is open on the opposite side to the nozzle and in which the sealing material50filled in the radially inner side of the cooling jacket covers the outer periphery of the molded resin is exposed to the space on the opening side of the cooling jacket. The distance in the radial direction between the molded resin and the inner jacket may be constant in the entirety of the circumference direction. Further, the through-hole to cause the sealing material to flow need not be formed in the molded resin.

(6f) The cooling fluid flowing through the flow path of the cooling jacket may be a fluid other than water. For example, the cooling fluid may be air.

(6g) The multiple functions of one component in the above embodiment may be realized by multiple components, or a function of one component may be realized by the multiple components. A plurality of functions of a plurality of elements may be implemented by one element, or one function implemented by a plurality of elements may be implemented by one element. In addition, a part of the configuration of the described above embodiment may be omitted. At least a part of the configuration of the described above embodiment may be added to or replaced with another configuration of the described above embodiment.

The harnesses42may be one or may be three or more.