Vibration insulator for fuel injection device

Abstract

The present invention provides a vibration damping insulator for a fuel injection device that can suppress noise caused by the working vibration of the fuel injection device. The vibration damping insulator suppresses vibration transmitted between the fuel injection valve and the cylinder head. The fuel injection valve is installed in an insertion hole of the cylinder head. The fuel injection valve has a stepped portion that is tapered and reduced in diameter so as to form an outer peripheral side conical surface facing a shoulder provided at an inlet portion of the insertion hole. The vibration damping insulator suppresses vibration by being clamped between the stepped portion and the shoulder. The vibration damping insulator includes: an annular tolerance ring having a bottom surface facing the shoulder and an inner peripheral side conical surface facing the outer peripheral side conical surface; and a vibration damping resin layer provided on the bottom surface or the inner peripheral side conical surface of the tolerance ring. The vibration damping resin layer includes a heat-resistant resin and a vibration damping filler that converts vibration energy into heat energy.

Description

Technical Field

[0001] The present invention relates to a vibration-damping insulator for a fuel injection device for suppressing vibration transmitted between a fuel injection valve for injecting fuel into an internal combustion engine and a cylinder head. Background Art

[0002] In the past, for example, in a cylinder head of an internal combustion engine of a type that injects fuel into a combustion chamber, a so-called in-cylinder injection type internal combustion engine, a portion of a fuel injection valve provided by a fuel injection device near the top end is inserted through an insertion hole supported in the cylinder head, and a portion of the fuel injection valve near the base end is inserted through a delivery pipe (fuel injection valve seat) and supported, so that the fuel injection valve is arranged between the cylinder head and the delivery pipe. In addition, in such a fuel injection valve, a mechanism for opening and closing a valve needle is usually provided in order to control the injection of fuel, and vibration is generated when the valve needle is seated, and the vibration may be transmitted to the cylinder head. In addition, since the vibration generated on the combustion chamber side is transmitted to the fuel injection valve via the cylinder head, it may be impossible to control the opening and closing of the fuel injection valve with high precision. Therefore, in order to suppress such a problem, a vibration-damping insulator that absorbs and suppresses these vibrations is sometimes installed between the fuel injection valve and the insertion hole of the cylinder head.

[0003] As such a vibration-damping insulator, for example, International Publication No. 2011 / 121728 describes a vibration-damping insulator for a fuel injection valve that suppresses the above-mentioned vibration, and the vibration-damping insulator includes: an annular vibration-damping member; an annular plate formed into a cross-sectional channel shape that encloses the lower portion (lower side of FIG. 2 of International Publication No. 2011 / 121728) and the inner peripheral portion (left side of FIG. 2) of the vibration-damping member; and an annular tolerance ring, the annular tolerance ring being provided at the upper portion (upper side of FIG. 2) of the vibration-damping member (refer to FIG. 2, etc.). In the vibration-damping insulator, the vibration-damping member is a member for absorbing and suppressing the vibration of the fuel injection valve, and includes an elastic member such as rubber, a coil spring annularly embedded in the elastic member, and a sleeve disposed at a position closer to the outer peripheral side than the coil spring and also annularly embedded in the elastic member.

[0004] In the vibration-damping insulator described in International Publication No. 2011 / 121728, the annular tolerance ring supports the fuel injection valve on the cylinder head by abutting against the outer peripheral tapered surface of the fuel injection valve, and is formed of a metal such as stainless steel. In addition, the inner end of the plate is bent toward the outer peripheral side in a manner of abutting against a connecting portion that is a connecting slope extending obliquely from the bottom surface of the tolerance ring toward the outer peripheral side. In addition, the plate is formed of a metal such as stainless steel, and the lower surface of the bottom of the plate abuts against the shoulder of the insertion hole of the cylinder head.

[0005] In the structure of such a conventional vibration damping insulator, as a path for transmitting vibration between the fuel injection valve and the cylinder head, there is a path composed only of members that easily transmit vibration, such as metal members like tolerance rings and plates. Therefore, the operating vibration of the fuel injection device, for example, the vibration generated when the needle inside the fuel injection device moves forward and backward to open and close the fuel injection valve, is transmitted from the fuel injection valve to the cylinder head through a path composed only of members that easily transmit vibration, such as metal members, and thus may be radiated to the outside as noise.

[0006] On the other hand, with the electrification of vehicles such as automobiles, the requirement level for NV (noise and vibration) performance has been further improved compared to the past. Therefore, countermeasures against the above-mentioned noise are required. Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] The present invention has been completed in view of such problems, and an object thereof is to provide a vibration damping insulator for a fuel injection device that can suppress noise caused by the operating vibration of the fuel injection device.

[0009] In order to solve the above problems, the vibration damping insulator for a fuel injection device of the present invention is a vibration damping insulator that suppresses vibration transmitted between a fuel injection valve and a cylinder head, and is characterized in that the fuel injection valve is installed on the cylinder head in a state of being inserted into an insertion hole provided in the cylinder head, a shoulder is provided by expanding the inlet portion of the insertion hole into a ring shape, the fuel injection valve has a stepped portion that is tapered and reduced in diameter so as to form an outer peripheral side conical surface facing the shoulder, the vibration damping insulator is configured to suppress the vibration by being sandwiched between the stepped portion and the shoulder, the vibration damping insulator includes: a ring-shaped tolerance ring having a bottom surface facing the shoulder and an inner peripheral side conical surface facing the outer peripheral side conical surface; and a vibration damping resin layer provided on the bottom surface or the inner peripheral side conical surface of the tolerance ring, and the vibration damping resin layer includes a heat-resistant resin and a vibration damping filler that converts vibration energy into heat energy.

[0010] According to the vibration damping insulator for a fuel injection device of the present invention, noise caused by the operating vibration of the fuel injection valve can be suppressed.

[0011] In the vibration damping insulator for a fuel injection device, it may also be that the vibration damping resin layer is provided on the bottom surface of the tolerance ring.

[0012] In the vibration damping insulator for a fuel injection device, it may also be that the thickness of the vibration damping resin layer is 10 μm or more.

[0013] According to the present invention, noise caused by the working vibration of the fuel injection valve can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the drawings, in which like reference numerals denote like parts, and in the drawings:

[0015] Figure 1 is a cross-sectional view schematically showing a fuel injection device to which a vibration isolator for a fuel injection device according to the first embodiment is applied.

[0016] Figure 2A is Figure 1 an enlarged view of part X shown, and is a cross-sectional view schematically showing a vibration isolator for a fuel injection device according to the first embodiment.

[0017] Figure 2B is a cross-sectional view schematically showing a vibration isolator for a fuel injection device according to the second embodiment, and is a view corresponding to Figure 2A corresponding thereto.

[0018] Figure 2C is a cross-sectional view schematically showing a vibration isolator for a fuel injection device according to the third embodiment, and is a view corresponding to Figure 2A corresponding thereto.

[0019] Figure 3 is a cross-sectional view schematically showing a falling ball test machine.

[0020] Figure 4 is a graph showing the sound pressure level of the sound generated at the time of collision of a steel ball with respect to the thickness of the vibration damping resin layer in the test pieces of Examples 1 to 11 and Comparative Example 1.

[0021] Figure 5 is a graph showing the acceleration level of the vibration transmitted to the cylinder head in three types of mounted vibration isolators having different formation positions of the vibration damping resin layer obtained in Examples 7, 9, and 11. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the vibration isolator for a fuel injection device of the present invention will be described. In addition, hereinafter, the "vibration isolator for a fuel injection device" may sometimes be simply referred to as a "vibration isolator".

[0023] (First Embodiment)

[0024] First, the vibration isolator for a fuel injection device according to the first embodiment will be described. Figure 1 is a cross-sectional view schematically showing a fuel injection device to which a vibration isolator for a fuel injection device according to the first embodiment is applied. Figure 2A isFigure 1 The enlarged view of the X part shown is a cross-sectional view schematically showing a vibration insulator for a fuel injection device according to the first embodiment.

[0025] As Figure 1 As shown, a fuel injection valve 11 is provided in the fuel injection device 10. A portion near the tip of the fuel injection valve 11 is supported by an insertion hole 15 of a cylinder head 12, and a portion near the base end of the fuel injection valve 11 is supported by a fuel injection valve seat 14 of a delivery pipe 13. Thus, the fuel injection valve 11 is mounted between the cylinder head 12 and the delivery pipe 13.

[0026] The insertion hole 15 of the cylinder head 12 is provided as a multi-stage hole whose hole diameter gradually decreases as it goes from the outer surface 12s of the cylinder head 12 toward the inner surface (not shown) so as to penetrate from the outer surface 12s of the cylinder head 12 to the inner surface. That is, the hole diameter of an inlet portion 17, which is an inlet portion starting from the outer surface 12s of the cylinder head 12, is the largest, and the hole diameter of a tip hole portion 16 opening at the inner surface is the smallest. Therefore, stepped portions based on the difference in hole diameter are respectively provided at portions where the hole diameter of the insertion hole 15 changes. Here, a stepped portion between the inlet portion 17 and a hole diameter portion 19 below the inlet portion 17 among these stepped portions is particularly referred to as a shoulder 18. The shoulder 18 is provided by expanding the inlet portion 17 of the insertion hole 15 into a ring shape. The tip hole portion 16 of the insertion hole 15 communicates with a combustion chamber of an in-cylinder injection type internal combustion engine. The fuel injection valve 11 is mounted on the cylinder head 12 in a state of being inserted through the insertion hole 15, and an injection nozzle 23 of the fuel injection valve 11 is mounted on the tip hole portion 16 of the insertion hole 15. The tip hole portion 16 guides high-pressure fuel ejected from the injection nozzle 23 into the combustion chamber.

[0027] The delivery pipe 13 supplies high-pressure fuel pressurized to an injection pressure in the delivery pipe 13 to the fuel injection valve 11 and has a fuel injection valve seat 14 into which the base end portion of the fuel injection valve 11 is inserted and mounted. The sealing performance between the fuel injection valve 11 and the inner peripheral surface 14a of the fuel injection valve seat 14 is ensured by an O-ring 29 disposed therebetween.

[0028] The fuel injection valve 11 injects the high-pressure fuel supplied from the delivery pipe 13 into the combustion chamber communicating with the cylinder head 12 at a predetermined timing. The housing of the fuel injection valve 11 has a multi-stage cylindrical shape and gradually tapers from the center toward the base end side. Specifically, the center of the housing of the fuel injection valve 11 is a large-diameter portion 20, and successively has a base-end relay portion 26 with a diameter smaller than that of the large-diameter portion 20, a base-end insertion portion 27 with a diameter smaller than that of the base-end relay portion 26, and a base-end sealed portion 28 with a diameter smaller than that of the base-end insertion portion 27, from the large-diameter portion 20 toward the base end. A connector 26J is provided in the base-end relay portion 26, and the connector 26J is connected to a wiring for transmitting a drive signal to an electromagnetic valve or the like built in the fuel injection valve 11. The base-end sealed portion 28 is inserted into the inside of the O-ring 29.

[0029] The O-ring 29 is formed of an elastic member such as rubber resistant to fuel into a substantially circular ring shape and has pressure resistance against the high-pressure fuel pressure. The inner circumference of the O-ring 29 is in close contact with the outer circumferential surface of the base-end sealed portion 28. By the close contact between the inner circumference of the O-ring 29 and the outer circumferential surface of the base-end sealed portion 28, the sealing property for preventing fuel leakage of the high-pressure fuel between the fuel injection valve 11 and the O-ring 29 is exhibited. The outer circumference of the O-ring 29 is formed to be in close contact with the inner circumferential surface 14a of the fuel injection valve seat 14 of the delivery pipe 13. That is, when the base end portion of the fuel injection valve 11 is inserted into the fuel injection valve seat 14 of the delivery pipe 13, the sealing property against the high-pressure fuel is exhibited by the close contact between the outer circumference of the O-ring 29 and the inner circumferential surface 14a of the fuel injection valve seat 14. By making the O-ring 29 exhibit the sealing property for each of the outer circumferential surface of the base-end sealed portion 28 and the inner circumferential surface 14a of the fuel injection valve seat 14 in this way, the sealing property against the high-pressure fuel is ensured between the fuel injection valve 11 and the fuel injection valve seat 14.

[0030] In addition, the sealing performance for high-pressure fuel ensured by the O-ring 29 between the fuel injection valve 11 and the fuel injection valve seat 14 is maintained at a relatively high level, for example, when the axis C of the fuel injection valve 11 coincides with the axis of the fuel injection valve seat 14, or when the gap between the outer peripheral surface of the base-end sealing portion 28 and the inner peripheral surface 14a of the fuel injection valve seat 14 is uniform over the entire circumference. That is, the thickness of the O-ring 29 becomes uniform over the entire circumference between the outer peripheral surface of the base-end sealing portion 28 and the inner peripheral surface 14a of the fuel injection valve seat 14, ensuring uniform sealing performance. On the other hand, when the gap between the outer peripheral surface of the base-end sealing portion 28 and the inner peripheral surface 14a of the fuel injection valve seat 14 is not uniform over the entire circumference, the thickness of the O-ring 29 is not uniform over the entire circumference. That is, although the O-ring 29 generates a large reaction force and exhibits a high clinging force at the portion where it is strongly pressed and thinned, conversely, at the portion where it is not strongly pressed, the reaction force becomes smaller and the clinging property decreases. When the position of the axis C of the fuel injection valve 11 and the position of the axis of the fuel injection valve seat 14 deviate near the center of the O-ring 29, the sealing performance between the fuel injection valve 11 and the fuel injection valve seat 14 decreases, and fuel leakage of high-pressure fuel may occur.

[0031] The housing of the fuel injection valve 11 gradually tapers from the center toward the tip side, and sequentially includes a medium-diameter portion 21 having a diameter smaller than that of the large-diameter portion 20 and a small-diameter portion 22 having a diameter smaller than that of the medium-diameter portion 21 from the large-diameter portion 20 toward the tip. An injection nozzle 23 for injecting fuel is provided at the tip of the small-diameter portion 22. At a position on the base-end side of the small-diameter portion 22 closer to the base-end than the injection nozzle 23, a sealing portion 25 for ensuring sealing performance is provided between the small-diameter portion 22 and the inner peripheral surface 16a of the tip hole portion 16 in order to maintain the airtightness of the combustion chamber communicating with the insertion hole 15.

[0032] Between the large-diameter portion 20 and the medium-diameter portion 21 of the housing of the fuel injection valve 11, a stepped portion 24 is provided based on the difference between the outer diameter of the large-diameter portion 20 and the outer diameter of the medium-diameter portion 21. The stepped portion 24 has a shape that tapers in a conical shape toward the tip side of the fuel injection valve 11 with an outer peripheral side conical surface 24s. The shape of the outer peripheral side conical surface 24s becomes a shape that narrows toward the tip side of the fuel injection valve 11. The outer peripheral side conical surface 24s of the stepped portion 24 of the fuel injection valve 11 faces the annular shoulder 18 at the entrance portion 17 of the insertion hole 15 in the cylinder head 12.

[0033] As Figure 1 and Figure 2A shown, the vibration insulator 30 of Embodiment 1 is an annular vibration insulator that suppresses vibration transmitted between the fuel injection valve and the cylinder head, and is configured to damp the vibration by being sandwiched between the stepped portion 24 and the shoulder 18.

[0034] The outer diameter of the vibration damping insulator 30 is set to a size that can be placed on the annular shoulder 18, and the inner diameter of the vibration damping insulator 30 is set to a size that allows the middle diameter portion 21 of the fuel injection valve 11 to be inserted into the inside of the vibration damping insulator 30 with a clearance between the vibration damping insulator 30 and the middle diameter portion 21. In addition, a ring 21R having an outer circumference larger than the inner circumference of the vibration damping insulator 30 is provided on the tip side of the middle diameter portion 21 of the fuel injection valve 11. The ring 21R is used to prevent the vibration damping insulator 30 through which the middle diameter portion 21 is inserted from detaching from the middle diameter portion 21.

[0035] The vibration damping insulator 30 includes an annular tolerance ring 33. The tolerance ring 33 is formed of stainless steel. In addition, as Figure 2A shown, the cross section of the tolerance ring 33 is in the shape of a right triangle, having a bottom surface 40, an inner peripheral surface 46, an outer peripheral surface 41, and an inner peripheral inclined surface 42 that extends obliquely upward from the upper end of the inner peripheral surface 46 to the upper end of the outer peripheral surface 41. The bottom surface 40 faces the annular shoulder 18 of the inlet portion 17 of the insertion hole 15. The inner peripheral inclined surface 42 is the inner peripheral side surface that forms a concave shape around the center of the ring of the tolerance ring 33, and forms Figure 2A the tapered shape of the cross section of the tolerance ring 33 shown.

[0036] The inner peripheral inclined surface 42 has a connecting portion 43 as a connecting inclined surface that extends obliquely upward from the upper end of the inner peripheral surface 46 toward the outer peripheral side, and an inner peripheral side tapered surface 45 that is one step higher than the connecting portion 43 and further extends obliquely upward toward the outer peripheral side. The inner peripheral edge of the connecting portion 43 is continuous with the inner peripheral edge of the bottom surface 40 via the inner peripheral surface 46. The shape of the inner peripheral side tapered surface 45 becomes a shape that expands toward the base end side of the fuel injection valve 11 so as to face the outer peripheral side tapered surface 24s of the fuel injection valve 11.

[0037] The inner peripheral side tapered surface 45 includes an inner side tapered surface 45a that is one step higher than the connecting portion 43 and extends obliquely upward toward the outer peripheral side, and an outer side tapered surface 45b that extends obliquely upward toward the outer peripheral side at a lower angle from the inner side tapered surface 45a, and forms a contact portion 44 that faces the outer peripheral side tapered surface 24s of the fuel injection valve 11.

[0038] The ridge line 47 that is the boundary between the inner side tapered surface 45a and the outer side tapered surface 45b of the inner peripheral side tapered surface 45 is at Figure 2Ais shown as the vertex of the portion protruding from the contact portion 44 toward the outer peripheral side conical surface 24s side. That is, the ridge line 47 is the position where the outer peripheral edge of the inner conical surface 45a abuts against the inner peripheral edge of the outer conical surface 45b, and the inner conical surface 45a and the outer conical surface 45b constitute the two-stage inner peripheral side conical surface 45. Here, when the angle of the conical surface is set as the inclination angle with respect to the parallel line C1 of the axis C of the tolerance ring, the angle of the inner conical surface 45a is set to be smaller than the angle of the outer peripheral side conical surface 24s of the fuel injection valve 11, and the angle of the outer conical surface 45b is set to be larger than the angle of the outer peripheral side conical surface 24s of the fuel injection valve 11. Therefore, the ridge line 47 is Figure 2A shown as the vertex in point contact with the outer peripheral side conical surface 24s of the fuel injection valve 11. That is, the inner peripheral side conical surface 45 abuts against the outer peripheral side conical surface 24s through line contact at the ridge line 47.

[0039] As Figure 1 and Figure 2A shown, the vibration insulator 30 further includes a vibration damping resin layer 31a provided on the bottom surface 40 of the tolerance ring 33. Thus, the vibration insulator 30 abuts against the shoulder 18 of the insertion hole 15 of the cylinder head 12 only through the vibration damping resin layer 31a. And the vibration damping resin layer 31a includes a heat-resistant resin and a vibration damping filler that converts vibration energy into heat energy. On the other hand, the vibration insulator 30 abuts against the outer peripheral side conical surface 24s of the fuel injection valve 11 through the inner peripheral side conical surface 45 of the tolerance ring 33. Thus, the vibration insulator 30 supports the fuel injection valve 11 with respect to the cylinder head 12.

[0040] Therefore, in the structure of the vibration insulator 30 of the first embodiment, there is a vibration damping resin layer 31a that can effectively cut off the transmission of vibration on the path where vibration is transmitted between the fuel injection valve 11 and the cylinder head 12. Thus, for example, it is possible to suppress the case where the working vibration of the fuel injection device such as the vibration generated when the needle moves forward and backward to open and close the fuel injection valve is transmitted from the fuel injection valve to the cylinder head and radiated to the outside of the vehicle and the inside of the vehicle compartment as noise. Moreover, it is also possible to suppress the case where the working vibration is transmitted from the fuel injection valve to the cylinder head and causes false detection of a sensor for detecting abnormal combustion represented by knocking.

[0041] In addition, the inner peripheral side conical surface 45 of the tolerance ring 33 is composed of two levels, namely, an inner conical surface 45a and an outer conical surface 45b, between which there is a ridge line protruding toward the outer peripheral side conical surface 24s side, and abuts against the outer peripheral side conical surface 24s through line contact at the ridge line 47. Therefore, when the axis C of the fuel injection valve 11 is inclined, the fuel injection valve 11 can slide on the ridge line 47 of the inner peripheral side conical surface 45 of the tolerance ring 33. Thereby, it is possible to suppress the situation where the reaction force from the vibration insulator 30 acts along with the inclination of the fuel injection valve 11. As a result, it is possible to avoid the following problem: such a reaction force causes a decrease in the sealing performance between the fuel injection valve 11 and the fuel injection valve seat 14 based on the O-ring 29.

[0042] Moreover, the vibration insulator 30 of the first embodiment is different from the vibration insulators 30 of the second and third embodiments described later, and the vibration damping resin layer is provided only on the bottom surface 40 of the tolerance ring 33. Therefore, compared with the second and third embodiments, the manufacturing process can be simplified and the manufacturing cost can be reduced.

[0043] (Second Embodiment)

[0044] Next, regarding the vibration insulator of the second embodiment, only the differences from the vibration insulator for the fuel injection device of the first embodiment will be described. Figure 2B is a cross-sectional view schematically showing the vibration insulator for the fuel injection device of the second embodiment, and is a view corresponding to Figure 2A corresponding figure.

[0045] The vibration insulator 30 of the second embodiment includes a vibration damping resin layer 31b provided on the inner peripheral side conical surface 45 of the tolerance ring 33 instead of the vibration damping resin layer 31a provided on the bottom surface 40 of the tolerance ring 33. Thereby, the vibration insulator 30 abuts against the outer peripheral side conical surface 24s of the fuel injection valve 11 only through the vibration damping resin layer 31b. And the vibration damping resin layer 31b contains a heat-resistant resin and a vibration damping filler that converts vibration energy into heat energy. On the other hand, the vibration insulator 30 abuts against the shoulder 18 of the insertion hole 15 of the cylinder head 12 through the bottom surface 40 of the tolerance ring 33. Thereby, the vibration insulator 30 supports the fuel injection valve 11 with respect to the cylinder head 12.

[0046] Therefore, in the structure of the vibration isolator 30 of the second embodiment, there is a vibration damping resin layer 31b on the path that enables vibration to be transmitted between the fuel injection valve 11 and the cylinder head 12 and that can effectively cut off the transmission of vibration. Thus, similar to the first embodiment, it is possible to suppress the case where the operating vibration of the fuel injection device is transmitted from the fuel injection valve to the cylinder head and radiated as noise to the outside of the vehicle or the like. On the other hand, different from the first embodiment, the inner peripheral side conical surface 45 of the tolerance ring 33 does not abut against the outer peripheral side conical surface 24s of the fuel injection valve 11 through line contact at the ridge line 47, so it is impossible to sufficiently suppress the case where the reaction force from the vibration isolator 30 acts along with the inclination of the fuel injection valve 11.

[0047] (Third Embodiment)

[0048] Next, regarding the vibration isolator for a fuel injection device of the third embodiment, only the differences from the vibration isolator for a fuel injection device of the first embodiment will be described. Figure 2C is a cross-sectional view schematically showing the vibration isolator for a fuel injection device of the third embodiment, and is a view corresponding to Figure 2A the corresponding figure.

[0049] The vibration isolator 30 of the third embodiment includes, in addition to the vibration damping resin layer 31a provided on the bottom surface 40 of the tolerance ring 33, a vibration damping resin layer 31b provided on the inner peripheral side conical surface 45 of the tolerance ring 33. Thus, the vibration isolator 30 abuts against the shoulder 18 of the insertion hole 15 of the cylinder head 12 only through the vibration damping resin layer 31a. And the vibration damping resin layer 31a includes a heat-resistant resin and a vibration damping filler that converts vibration energy into heat energy. Moreover, the vibration isolator 30 abuts against the outer peripheral side conical surface 24s of the fuel injection valve 11 only through the vibration damping resin layer 31b. And the vibration damping resin layer 31b includes a heat-resistant resin and a vibration damping filler that converts vibration energy into heat energy. Thus, the vibration isolator 30 supports the fuel injection valve 11 with respect to the cylinder head 12.

[0050] Therefore, in the structure of the vibration isolator 30 of the third embodiment, there are a vibration damping resin layer 31a and a vibration damping resin layer 31b on the path that enables vibration to be transmitted between the fuel injection valve 11 and the cylinder head 12 and that can effectively cut off the transmission of vibration. Thus, compared with the first embodiment, it is possible to more effectively suppress the case where the operating vibration of the fuel injection device is transmitted from the fuel injection valve to the cylinder head and radiated as noise to the outside of the vehicle or the like. On the other hand, different from the first embodiment, the inner peripheral side conical surface 45 of the tolerance ring 33 does not abut against the outer peripheral side conical surface 24s of the fuel injection valve 11 through line contact at the ridge line 47, so it is impossible to sufficiently suppress the case where the reaction force from the vibration isolator 30 acts along with the inclination of the fuel injection valve 11.

[0051] Hereinafter, the details of each structure of the vibration insulator for a fuel injection device according to the embodiment will be described.

[0052] 1. Tolerance ring

[0053] The tolerance ring is an annular member having a bottom surface facing the shoulder and an inner peripheral tapered surface facing the outer peripheral tapered surface. Examples of the material of the tolerance ring include metals such as SUS304 stainless steel, which is a hard stainless steel material. As the material of the tolerance ring, a metal having the same hardness as the outer peripheral tapered surface of the fuel injection valve may also be used.

[0054] 2. Vibration damping resin layer

[0055] The vibration damping resin layer is provided on the bottom surface or the inner peripheral tapered surface of the tolerance ring. The vibration damping resin layer includes a heat-resistant resin and a vibration damping filler that converts vibration energy into heat energy.

[0056] As the vibration damping resin layer, a vibration damping resin layer provided on the bottom surface of the tolerance ring is preferably used. This is because, as in the first embodiment, since the inner peripheral tapered surface of the tolerance ring can be in line contact with the outer peripheral tapered surface of the fuel injection valve, it is possible to suppress the case where the reaction force from the vibration insulator acts along with the inclination of the fuel injection valve. Moreover, the manufacturing process can be simplified and the manufacturing cost can be reduced.

[0057] The thickness of the vibration damping resin layer is not particularly limited. For example, it is preferably 10 μm or more, more preferably 20 μm or more, and particularly preferably 50 μm or more. This is because the cut-off effect of vibration transmission can be sufficiently obtained. The thickness of the vibration damping resin layer is preferably 400 μm or less, more preferably 200 μm or less, and particularly preferably 100 μm or less. This is because the improvement of the vibration cut-off effect saturates and it is easy to form a layer by coating.

[0058] The heat-resistant resin is not particularly limited as long as it has a heat distortion temperature of 100 °C or higher. A resin having a heat distortion temperature of 150 °C or higher is preferred. Examples of the heat-resistant resin are not particularly limited, and polyamideimide resin, polyimide resin, phenolic resin, epoxy resin, polyethersulfone resin, polyphenylene sulfide resin, etc. can be cited. From the viewpoints of workability when forming a coating film and heat resistance against heat generation caused by friction, polyamideimide resin is further preferred. These heat-resistant resins may be used alone or in combination of two or more.

[0059] The vibration damping filler converts vibration energy into heat energy. As the vibration damping filler, there is no particular limitation, and it can be roughly classified into materials that are easily deformed with a low elastic modulus and materials that easily generate energy dissipation inside. More specifically, the materials that are easily deformed with a low elastic modulus are solids, but materials that significantly have both elastic properties and viscous properties. Elastic properties and viscous properties are properties possessed by all materials, but the materials that are easily deformed with a low elastic modulus significantly have both of the above properties. Therefore, by making the vibration damping resin layer contain materials that are easily deformed with a low elastic modulus, the rubber elasticity of the vibration damping resin layer itself in the normal temperature region can be increased. Thus, it is considered that by effectively absorbing the vibration input from the outside and converting it into heat energy using the vibration damping resin layer, the transmission of vibration can be effectively cut off. On the other hand, the materials that easily generate energy dissipation inside have the effect of attenuating vibration by causing the vibration to diffusely reflect in the air layer existing in the material and converting it into heat energy. Therefore, it is considered that when the vibration damping resin layer contains materials that easily generate energy dissipation inside, the transmission of vibration can be effectively cut off using the vibration damping resin layer.

[0060] Examples of the materials that are easily deformed with a low elastic modulus include thermoplastic elastomers, polyurethane-based compounds, polyethylene-based compounds, ester copolymers, rubber-based materials, etc. Thermoplastic elastomers generally have the properties of rubber at normal temperature and the same performance as thermoplastic plastics at high temperature. Examples of thermoplastic elastomers include styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, ester-based thermoplastic elastomers, amide-based thermoplastic elastomers, etc. These examples are listed, for example, in Japanese Unexamined Patent Application Publication No. 2016-113614, Japanese Unexamined Patent Application Publication No. 2017-197733, etc. Examples of polyurethane-based compounds include polyurethane resins, etc. These examples are listed, for example, in Japanese Unexamined Patent Application Publication No. 8-183945, etc. Examples of polyethylene-based compounds include homopolymers of ethylene, copolymers of ethylene and α-olefin monomers, etc. These examples are listed, for example, in Japanese Patent Application Laid-Open No. 2009-532570, etc. Examples of ester copolymers include acrylate copolymers, etc. These examples are listed, for example, in Japanese Patent No. 3209499, etc. Examples of rubber-based materials include butyl rubber, fluororubber, etc. These examples are listed, for example, in Japanese Unexamined Patent Application Publication No. 2009-236172, etc.

[0061] Examples of materials that are liable to generate energy dissipation inside include microcapsule-based materials, low-density materials, etc. Examples of microcapsule-based materials include thermally expandable microcapsules in which a gasifying substance that expands when reaching a predetermined temperature range is encapsulated inside a shell made of a thermoplastic polymer. These examples are listed in Japanese Patent Application Laid-Open No. 2013-18855, etc. Examples of low-density materials are all materials containing an air layer inside the material. Specifically, for example, foamed materials, porous bodies, non-woven fabrics, layered compounds, etc. can be cited. These examples are listed in, for example, Japanese Patent Application Laid-Open No. 3-221173, Japanese Patent No. 4203589, etc. The vibration damping fillers listed above can be used alone or in combination of two or more.

[0062] In addition to the heat-resistant resin and the vibration damping filler, the vibration damping resin layer can also contain optional components such as solid lubricants and hard particles. This is because properties such as abrasion resistance, sintering resistance, and low friction characteristics can be imparted to the vibration damping resin layer. There is no particular limitation on the solid lubricant. For example, polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS2), graphite, etc. can be cited. These solid lubricants can be used alone or in combination of two or more. There is no particular limitation on the hard particles, and alumina (Al2O3), silica, etc. can be cited. These hard particles can be used alone or in combination of two or more.

[0063] The volume ratio of the vibration damping filler to the total volume of the heat-resistant resin and the vibration damping filler in the vibration damping resin layer is not particularly limited. For example, it is preferably 20% by volume or more and 80% by volume or less, and more preferably in the range of 40% by volume or more and 60% by volume or less. This is because, by being above the lower limit of the above range, the filler can convert vibration energy into heat more efficiently. In addition, by being below the upper limit of the above range, the durability of the resin coating (such as abrasion resistance, adhesion, etc.) can be ensured. In addition, the volume ratio of optional components other than the heat-resistant resin and the vibration damping filler in the vibration damping resin layer is not particularly limited and can be selected according to the type. In addition, the vibration damping resin layer is not particularly limited as long as it is a layer that attenuates vibration of a desired frequency transmitted between the fuel injection valve and the cylinder head. For example, it is preferably a layer that attenuates vibration of 2 kHz. This is because it can particularly effectively suppress noise caused by the working vibration of the fuel injection valve. In addition, in order to adjust the vibration damping resin layer to be a layer that attenuates vibration of a desired frequency, for example, it is only necessary to adjust the types, contents, thickness of the vibration damping filler, heat-resistant resin, etc. in the vibration damping resin layer.

[0064] The method for forming the vibration damping resin layer is not particularly limited, and for example, the following methods can be cited. First, a solution is prepared by dissolving a predetermined amount of heat-resistant resin in an organic solvent. Next, a predetermined amount of vibration damping filler is added to the solution, and if necessary, any other components are further added and kneaded to prepare a coating material. Then, the coating material is applied to the bottom surface or the inner peripheral tapered surface of the tolerance ring. Next, the coating material applied to the tolerance ring is heated to dry and cure it. Thus, the vibration damping resin layer is formed.

[0065] The organic solvent used in the above method is not particularly limited and is selected according to the type of heat-resistant resin. As the organic solvent, for example, when using polyamideimide resin as the heat-resistant resin, N-methyl-2-pyrrolidone (NMP), N-ethylpyrrolidone (NEP), 1,3-dimethyl-2-imidazolidinone (DMI), γ-butyrolactone (GBL), etc. can be cited. In addition, when using epoxy resin, methyl ethyl ketone (MEK), toluene, etc. can be cited.

[0066] The kneading method for preparing the coating material, for example, can be a method of kneading for 1 hour using a kneader. The method of applying the coating material to the tolerance ring is not particularly limited, and general coating methods can be used, such as spraying, screen printing, dipping, etc. The heating conditions for drying and curing the coating material are not particularly limited, and for example, conditions such as heating at a temperature of 100 °C or higher and 370 °C or lower for 30 minutes or more and 3 hours or less can be cited.

[0067] 3. Vibration Damping Insulator for Fuel Injection Device

[0068] The vibration damping insulator for a fuel injection device is a vibration damping insulator for a fuel injection device that suppresses vibration transmitted between a fuel injection valve and a cylinder head. The fuel injection valve is installed in the cylinder head in a state of being inserted into an insertion hole provided in the cylinder head, and a shoulder is provided by expanding the inlet portion of the insertion hole into a ring shape. The fuel injection valve has a stepped portion that is tapered and reduced in diameter so as to form an outer peripheral tapered surface facing the shoulder, and the vibration damping insulator is configured to suppress the vibration by being sandwiched between the stepped portion and the shoulder.

[0069] The internal combustion engine to which the vibration damping insulator for a fuel injection device is applied is not particularly limited. For example, it is an in-cylinder injection type internal combustion engine, which can be either a gasoline internal combustion engine or a diesel internal combustion engine.

[0070] Hereinafter, examples and comparative examples will be cited to further specifically illustrate the vibration damping insulator of the embodiment.

[0071] [Example 1]

[0072] First, prepare a coating material for forming a vibration-damping resin layer of a vibration-damping insulator. Specifically, first, prepare a polyamideimide resin as a heat-resistant resin, dissolve a predetermined amount in N-ethyl-2-pyrrolidone (NEP) (organic solvent) to prepare a solution. Next, prepare a thermoplastic elastomer as a vibration-damping filler, add a predetermined amount to the solution, and knead for 1 hour using a kneader. Thus, a coating material is prepared such that the volume ratio of the vibration-damping filler to the total volume of the heat-resistant resin and the vibration-damping filler in the vibration-damping resin layer is 50% by volume.

[0073] Next, produce a test piece having a vibration-damping resin layer formed on the surface of a massive substrate. Specifically, first, prepare a massive substrate made of SUS440C, and coat a predetermined amount of the coating material on the surface of the substrate by spraying. Next, by heating the coating material coated on the substrate at 180 °C for 90 minutes, the organic solvent is volatilized to dry and cure the coating material. Thus, a test piece is produced by forming a vibration-damping resin layer with a thickness of 1 μm on the surface of the substrate.

[0074] [Example 2]

[0075] A test piece is produced in the same manner as in Example 1 except that the vibration-damping resin layer is formed to have a thickness of 5 μm.

[0076] [Example 3]

[0077] A test piece is produced in the same manner as in Example 1 except that the vibration-damping resin layer is formed to have a thickness of 10 μm.

[0078] [Example 4]

[0079] A test piece is produced in the same manner as in Example 1 except that the vibration-damping resin layer is formed to have a thickness of 20 μm.

[0080] [Example 5]

[0081] A test piece is produced in the same manner as in Example 1 except that the vibration-damping resin layer is formed to have a thickness of 50 μm.

[0082] [Example 6]

[0083] A test piece is produced in the same manner as in Example 1 except that the vibration-damping resin layer is formed to have a thickness of 100 μm.

[0084] [Example 7]

[0085] First, a test piece is produced in the same manner as in Example 1 except that the vibration-damping resin layer is formed to have a thickness of 200 μm.

[0086] Next, a vibration damping insulator having a vibration damping resin layer formed on the bottom surface of the tolerance ring was manufactured and installed in the fuel injection device, thereby manufacturing an installed vibration damping insulator.

[0087] Specifically, first, a ring-shaped tolerance ring made of SUS440C was prepared. The tolerance ring has a bottom surface facing the shoulder of the insertion hole of the cylinder head and an inner peripheral tapered surface facing the outer peripheral tapered surface of the fuel injection valve. Next, a predetermined amount of the same coating material as in Example 1 was applied to the bottom surface of the tolerance ring by spraying. Then, the coating material applied to the tolerance ring was heated at 180°C for 90 minutes to volatilize the organic solvent, drying and curing the coating material. Thus, a vibration damping insulator was manufactured by forming a vibration damping resin layer with a thickness of 200 μm on the bottom surface of the tolerance ring.

[0088] Next, a cylinder head, a fuel injection valve, and a delivery pipe were prepared. An insertion hole was provided in the cylinder head, and a shoulder was provided by expanding the inlet portion of the insertion hole into a ring shape. The housing of the fuel injection valve has a multi-stage cylindrical shape and has a stepped portion that is tapered and reduced in diameter so as to form an outer peripheral tapered surface facing the shoulder of the insertion hole of the cylinder head. Next, the vibration damping insulator and the fuel injection valve were installed in the cylinder head, and then, after installing the delivery pipe, it was fastened with bolts. At this time, the vibration damping insulator was sandwiched between the shoulder and the stepped portion in such a way that the vibration damping insulator abutted against the shoulder of the insertion hole of the cylinder head only through the vibration damping resin layer and abutted against the outer peripheral tapered surface of the fuel injection valve through the inner peripheral tapered surface of the tolerance ring. Thus, an installed vibration damping insulator was manufactured.

[0089] Next, a vibration damping insulator having a vibration damping resin layer formed on the inner peripheral tapered surface of the tolerance ring was manufactured and installed in the fuel injection device, thereby manufacturing an installed vibration damping insulator. Specifically, first, except that the formation position of the vibration damping resin layer was set to the inner peripheral tapered surface of the tolerance ring, the vibration damping insulator was manufactured in the same manner as when manufacturing the vibration damping insulator having a vibration damping resin layer formed on the bottom surface of the tolerance ring as described above. Next, except that the vibration damping insulator was sandwiched between the shoulder and the stepped portion in such a way that the vibration damping insulator abutted against the shoulder of the insertion hole of the cylinder head through the bottom surface of the tolerance ring and abutted against the outer peripheral tapered surface of the fuel injection valve only through the vibration damping resin layer, the vibration damping insulator was installed in the fuel injection device in the same manner as when installing the vibration damping insulator having a vibration damping resin layer formed on the bottom surface of the tolerance ring as described above. Thus, an installed vibration damping insulator was manufactured.

[0090] Next, a vibration-damping insulator having vibration-damping resin layers formed on both the bottom surface and the inner peripheral side conical surface of the tolerance ring was fabricated and installed in the fuel injection device, thereby producing an installed vibration-damping insulator. Specifically, first, except that the formation sites of the vibration-damping resin layers were set to both the bottom surface and the inner peripheral side conical surface of the tolerance ring, a vibration-damping insulator was fabricated in the same manner as when fabricating a vibration-damping insulator having a vibration-damping resin layer formed on the bottom surface of the tolerance ring as described above. Next, except that the vibration-damping insulator was sandwiched between the shoulder portion and the stepped portion in such a way that the vibration-damping insulator abutted against the shoulder of the insertion hole of the cylinder head only through the vibration-damping resin layer on the bottom surface side and abutted against the outer peripheral side conical surface of the fuel injection valve only through the vibration-damping resin layer on the inner peripheral side, the vibration-damping insulator was installed in the fuel injection device in the same manner as when installing a vibration-damping insulator having a vibration-damping resin layer formed on the bottom surface of the tolerance ring as described above, thereby producing an installed vibration-damping insulator.

[0091] [Example 8]

[0092] First, except for preparing a polyurethane resin as a vibration-damping filler and adding a predetermined amount to the solution, a coating material was prepared in the same manner as in Example 1.

[0093] Next, except for using the coating material prepared in this example and forming a vibration-damping resin layer to a thickness of 100 μm, a test piece was fabricated in the same manner as in Example 1.

[0094] [Example 9]

[0095] First, except for forming a vibration-damping resin layer to a thickness of 200 μm, a test piece was fabricated in the same manner as in Example 8.

[0096] Next, except for using the same coating material as in Example 8, a vibration-damping insulator having a vibration-damping resin layer formed on the bottom surface of the tolerance ring was fabricated and installed in the fuel injection device in the same manner as in Example 7, thereby producing an installed vibration-damping insulator.

[0097] Next, except for using the same coating material as in Example 8, a vibration-damping insulator having a vibration-damping resin layer formed on the inner peripheral side conical surface of the tolerance ring was fabricated and installed in the fuel injection device in the same manner as in Example 7, thereby producing an installed vibration-damping insulator.

[0098] Next, except for using the same coating material as in Example 8, a vibration-damping insulator having vibration-damping resin layers formed on both the bottom surface and the inner peripheral side conical surface of the tolerance ring was fabricated and installed in the fuel injection device in the same manner as in Example 7, thereby producing an installed vibration-damping insulator.

[0099] [Example 10]

[0100] First, a coating material was prepared in the same manner as in Example 1 except that microcapsules were prepared as the vibration-damping filler and a predetermined amount was added to the dissolving liquid.

[0101] Next, a test piece was prepared in the same manner as in Example 1 except that the coating material prepared in this example was used and the vibration-damping resin layer was formed to have a thickness of 100 μm.

[0102] [Example 11]

[0103] First, a test piece was prepared in the same manner as in Example 10 except that the vibration-damping resin layer was formed to have a thickness of 200 μm.

[0104] Next, a vibration damping insulator having a vibration damping resin layer formed on the bottom surface of the tolerance ring was produced in the same manner as in Example 7 except that the same coating material as in Example 10 was used, and was mounted on the fuel injection device, thereby producing a mounted vibration damping insulator.

[0105] Next, a vibration damping insulator having a vibration damping resin layer formed on the inner circumferential tapered surface of the tolerance ring was produced in the same manner as in Example 7 except that the same coating material as in Example 10 was used, and was mounted on the fuel injection device, thereby producing a mounted vibration damping insulator.

[0106] Next, a vibration-damping insulator having a vibration-damping resin layer formed on both the bottom surface and the inner circumferential tapered surface of the tolerance ring was produced in the same manner as in Example 7 except that the same coating material as in Example 10 was used, and was mounted on the fuel injection device, thereby producing a mounted vibration-damping insulator.

[0107] [Comparative Example 1]

[0108] First, a block-shaped substrate similar to that in Example 1 was prepared as a test piece without forming a vibration-damping resin layer.

[0109] Next, prepare an annular tolerance ring similar to that of Example 7, and use it directly as a vibration-damping insulator without forming a vibration-damping resin layer. Next, prepare a cylinder head, a fuel injection valve, and a delivery pipe similar to that of Example 7. Next, install the vibration-damping insulator and the fuel injection valve on the cylinder head, and then tighten the delivery pipe with bolts after installing it. At this time, the vibration-damping insulator is sandwiched between the shoulder and the step portion in such a manner that the bottom surface of the tolerance ring abuts against the shoulder of the insertion hole of the cylinder head, and the inner circumferential tapered surface of the tolerance ring abuts against the outer circumferential tapered surface of the fuel injection valve. Thus, the vibration-damping insulator is installed in the fuel injection device, and thus a mounted vibration-damping insulator is produced.

[0110] [Evaluation of the influence of the thickness of the vibration damping resin layer on the NV performance in the drop ball test]

[0111] The test pieces obtained in Examples 1 to 11 and Comparative Example 1 were subjected to a ball drop test to evaluate the effect of the thickness of the vibration damping resin layer on the NV performance. Figure 3 It is a cross-sectional view schematically showing a ball drop testing machine.

[0112] In the ball drop test, as Figure 3 shown, the test piece was placed on a steel plate on an acceleration sensor (pickup) provided on the upper part of the base of the ball drop testing machine. At the time of setting, for the test pieces of Examples 1 to 11, the vibration damping resin layer was in contact with the steel plate. This is because the purpose of the ball drop test is to measure the degree to which noise is suppressed when an impact is applied to the vibration damping resin layer disposed in the gap between components. In the ball drop testing machine, a SUJ2 steel ball was held by an electromagnet directly above the test piece. In the ball drop test, the ball was dropped by setting the height of the ball before dropping (the distance from the upper surface of the test piece) to 500 mm and then turning off the magnetic force of the ball drop testing machine, so that the ball collided with the test piece. Then, the sound generated at the time of collision was collected by a microphone provided directly above the test piece, and the sound pressure level of the overall value in the frequency band of 20 Hz to 10 kHz was measured. The measurement results are shown in Table 1 below. Figure 4 It is a graph showing the sound pressure level of the sound generated at the time of collision of the steel ball with respect to the thickness of the vibration damping resin layer in the test pieces of Examples 1 to 11 and Comparative Example 1.

[0113] As shown in Table 1 below and Figure 4 shown, as the film thickness of the vibration damping resin layer increases, the sound pressure level decreases, so it can be considered that the NV performance improves as the film thickness of the vibration damping resin layer increases. If the test piece composed only of the base material in Comparative Example 1 and the test pieces of Examples 1 to 7 having the same composition of the vibration damping resin layer are compared, in the test pieces with a thickness of the vibration damping resin layer thinner than 10 μm, although a reduction effect of the sound pressure level with respect to the test piece composed only of the base material was confirmed, a large reduction effect was not confirmed. On the other hand, in the test pieces with a thickness of the vibration damping resin layer of 10 μm or more, a reduction effect of the sound pressure level of 5 dB or more was confirmed with respect to the test piece composed only of the base material. Therefore, as the thickness of the vibration damping resin layer, it is preferably 10 μm or more, more preferably 20 μm or more, and particularly preferably 50 μm or more. And, as shown in Table 1 below and Figure 4 shown, even if the type of the vibration damping filler in the vibration damping resin layer is changed, the same tendency was confirmed.

[0114] 〔Evaluation of NV Performance of Mounted Vibration Damping Insulator〕

[0115] The NV performance of the vibration damping insulator-mounted products obtained in Examples 7, 9, 11 and Comparative Example 1 was evaluated. Further, in the evaluation of the NV performance of the vibration damping insulator-mounted products obtained in Examples 7, 9 and 11, the NV performance was evaluated for three types of vibration damping insulator-mounted products in which the formation part of the vibration damping resin layer was the inner circumferential side conical surface, the bottom surface, and both surfaces, respectively.

[0116] Specifically, the fuel injection valve of the fuel injection device was connected to the waveform generator, and the acceleration sensor was mounted on the cylinder head of the fuel injection device. On this basis, a pulse wave with a frequency of 10 Hz was input to the fuel injection valve from the waveform generator at a certain duty ratio, so that the needle inside the fuel injection valve vibrated. Then, the acceleration level of the overall value of the vibration in the frequency band of 20 Hz to 20 kHz transmitted to the cylinder head was measured by the acceleration sensor. The measurement results are shown in Table 1 below. Figure 5 It is a graph showing the acceleration level of the vibration transmitted to the cylinder head in three types of vibration damping insulator-mounted products with different formation parts of the vibration damping resin layer obtained in Examples 7, 9 and 11. Further, in Figure 5 the graph, the acceleration level of the vibration transmitted to the cylinder head in the vibration damping insulator-mounted product obtained in Comparative Example 1 is indicated by a dashed line.

[0117] As shown in Table 1 below and Figure 5 shown, among the three types of vibration damping insulator-mounted products with different formation parts of the vibration damping resin layer obtained in Examples 7, 9 and 11, compared with the vibration damping insulator-mounted product obtained in Comparative Example 1, regardless of the formation part of the vibration damping resin layer, a significant reduction effect of the acceleration level was confirmed. When the vibration damping resin layer is formed on the bottom surface, the inner circumferential side conical surface, or both of the tolerance rings, it is considered that the transmission of the vibration generated by the fuel injection valve to the cylinder head is cut off by the vibration damping resin layer, and the acceleration level is reduced.

[0118] [Table 1]

[0119]

[0120] As described above, the embodiments of the vibration damping insulator for a fuel injection device of the present invention have been described in detail, but the present invention is not limited to the above embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims.

Claims

1. A vibration damping insulator for a fuel injection device, the vibration damping insulator for the fuel injection device suppressing vibration transmitted between a fuel injection valve and a cylinder head, wherein the fuel injection valve is mounted on the cylinder head in a state of being inserted into an insertion hole provided in the cylinder head, a shoulder is provided by expanding an inlet portion of the insertion hole of the cylinder head into a ring shape, the fuel injection valve has a stepped portion that is tapered and reduced in diameter so as to form an outer peripheral side conical surface facing the shoulder of the insertion hole of the cylinder head, and the vibration damping insulator is configured to suppress the vibration by being sandwiched between the stepped portion and the shoulder. The vibration damping insulator includes: a ring-shaped tolerance ring having a bottom surface facing the shoulder of the insertion hole of the cylinder head and an inner peripheral side conical surface facing the outer peripheral side conical surface of the fuel injection valve; and a vibration damping resin layer provided on the bottom surface or the inner peripheral side conical surface of the tolerance ring. When the vibration damping resin layer is provided on the bottom surface of the tolerance ring, only the vibration damping resin layer of the vibration damping insulator abuts against the shoulder of the insertion hole of the cylinder head. When the vibration damping resin layer is provided on the inner peripheral side conical surface of the tolerance ring, only the vibration damping resin layer of the vibration damping insulator abuts against the outer peripheral side conical surface of the fuel injection valve. The vibration damping resin layer contains a heat-resistant resin and a vibration damping filler that converts vibration energy into heat energy. The volume ratio of the vibration damping filler to the vibration damping resin layer is 20% by volume or more and 80% by volume or less.

2. The vibration damping insulator for a fuel injection device according to claim 1, wherein the thickness of the vibration damping resin layer is 10 μm or more.

Images