Patent Publication Number: US-9404458-B2

Title: Fuel injection valve damping insulator

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a fuel injection valve damping insulator that damps vibration produced in a fuel injection valve that injects fuel in an internal combustion engine. 
     2. Description of Related Art 
     Conventionally, in a so-called in-cylinder injection type internal combustion engine, that is a type of internal combustion engine in which fuel is injected into a combustion chamber, for example, a fuel injection valve is suspended between a cylinder head and a delivery pipe by having a portion toward a tip end of the fuel injection valve be inserted into and supported by an insertion hole of the cylinder head, and a portion toward the base end of the fuel injection valve be inserted into and supported by the delivery pipe (i.e., a fuel injection valve cup). Normally, in this kind of fuel injection valve, when fluctuations in the fuel pressure supplied via the delivery pipe occur due to the injection of fuel being started and stopped, vibration based on this fuel pressure fluctuation and operating vibration of the fuel injection valve occur. Therefore, a damping insulator that absorbs and suppresses vibration of the fuel injection valve is often installed between the fuel injection valve and the insertion hole of the cylinder head. 
     However, because the cylinder head and the delivery pipe are originally separate parts, the relative positions of these parts inevitably change due to tolerance related to machining and manufacturing of the parts, tolerance related to assembly during manufacture, and various vibrations and thermal deformation that occur with operation of the internal combustion engine, for example. That is, even with the fuel injection valve described above that is suspended between the cylinder head and the delivery pipe, the axis of the fuel injection valve becomes inclined with respect to the axis of the insertion hole of the cylinder head, and the fuel injection valve will become positionally offset at the position where it is supported by the cylinder head and the delivery pipe. This kind of positional offset may lead to a fuel leak by creating looseness in a portion of an O-ring that prevents fuel from leaking between the fuel injection valve and the delivery pipe (i.e., the fuel injection valve cup) or the like, at the base end side of the fuel injection valve. 
     Therefore, an insulator that aims to absorb and suppress vibration of a fuel injection valve, and reduce the effect from the axial inclination of the fuel injection has been proposed. The insulator described in Japanese Patent No. 4191734 is an example of one such insulator. The insulator described in Japanese Patent No. 4191734 includes an annular adjustment element  60  sandwiched between a shoulder portion  54  of a cylinder head  51  and a tapered stepped portion  57  of a fuel injection valve  55  that increases in diameter in a tapered shape so as to face the shoulder portion  54 , as shown in  FIG. 7 . An injection nozzle  56  of the fuel injection valve  55  is arranged inserted through an insertion hole  52  (i.e., a receiving hole) of the cylinder head  51 , and the shoulder portion  54  of the cylinder head  51  widens out to a side wall  53  of the insertion hole  52 . The adjustment element  60  includes a first leg  61  that extends along the shoulder portion  54  of the insertion hole  52 , and a second leg  62  that extends along the tapered stepped portion  57  of the fuel injection valve  55 . The fuel injection valve  55  is configured to be elastically supported with respect to the cylinder head  51  by the first leg  61  surface-contacting the shoulder portion  54  of the insertion hole  52 , and the second leg  62  surface-contacting the tapered stepped portion  57  of the fuel injection valve  55 . 
     With this kind of insulator, during assembly, if an axis C 2  of the fuel injection valve  55  becomes displaced between the insertion hole  52  of the cylinder head  51  and the delivery pipe, the first leg  61  will move along the shoulder portion  54  of the insertion hole  52  based on force generated by the second leg  62  that bends following the tapered stepped portion  57  of the fuel injection valve  55 . As a result, the positional relationship of the fuel injection valve  55  with respect to the insertion hole  52  and the delivery pipe is able to be appropriately compensated for. However, when the internal combustion engine is operating, high pressure based on the fuel pressure described above is applied to the adjustment element  60  through the tapered stepped portion  57  of the fuel injection valve  55 . At this time, the fuel injection valve  55  may no longer be able to elastically support the fuel injection valve  55  with respect to the cylinder head  51  due to metal fatigue from the fuel pressure accumulating in the adjustment element  60 , or the adjustment element  60  plastic deforming as a result of the adjustment element  60  receiving unexpected pressure or the like. The position in the vertical direction of the fuel injection valve  55  that is no longer able to be elastically supported in this way with respect to the cylinder head  51  moves, so the fuel injection position will also change, and the like. As a result, an optimum combustion state may no longer be able to be maintained. Also, the adjustment element  60  that has lost is elasticity will transmit vibration produced by the fuel injection valve  55  based on the fuel pressure to the cylinder head  51  without damping it. As a result, noise due to the transmitted vibration may emanate from the internal combustion engine, and sensors of the internal combustion engine may erroneously detect the transmitted vibration as knocking, and the like. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing problems, the invention thus provides a fuel injection valve damping insulator capable of suitably maintaining a fuel injection position of a fuel injection valve, as well as a damping function with respect to the fuel injection valve, when an internal combustion engine is operating. 
     Thus, a first aspect of the invention relates to a fuel injection valve damping insulator that damps vibration produced in a fuel injection valve. The fuel injection valve is installed in a cylinder head in a state inserted into an insertion hole provided in the cylinder head. A shoulder portion is formed widening out in an annular shape at an inlet portion of the insertion hole. The fuel injection valve includes a stepped portion in which a diameter thereof increases in a tapered shape so as to have a tapered surface that faces the shoulder portion. The damping insulator is interposed between the stepped portion and the shoulder portion. This damping insulator includes a tolerance ring that is an annular shape that abuts against the tapered surface, and an elastic member that is arranged between the tolerance ring and the shoulder portion. The elastic member is formed in an annular shape corresponding to a bottom surface of the tolerance ring to damp vibration produced in the fuel injection valve. A coil spring that is arranged in an annular shape corresponding to the annular shape of the elastic member, and an annular sleeve that is juxtaposed to the coil spring, are embedded in the elastic member. The sleeve is such that a height thereof is formed lower than an outer diameter of individual small ring portions that form a helix of the coil spring, and at least one of the tolerance ring side and the shoulder portion side of the sleeve is buried in the elastic member. 
     According to the structure of the fuel injection valve damping insulator described above, if the coil spring largely deforms from pressure or the like, such that the position of the fuel injection valve is maintained by the sleeve, at least one of the tolerance ring side and the shoulder portion side of the sleeve is buried in the elastic member, so the elastic member is interposed together with the sleeve between the fuel injection valve and the cylinder head. As a result, vibration transmitted from the fuel injection valve to the cylinder head via the sleeve can be reduced by the elastic member that is interposed midway along this path. That is, even if the coil spring largely deforms, the position of the fuel injection valve is able to be maintained by the sleeve, and vibration transmitted to the internal combustion engine is also able to be suppressed. As a result, even when the position of the fuel injection valve is maintained by the sleeve, vibration transmitted from the fuel injection valve to the internal combustion engine is suppressed, so noise that emanates from the internal combustion engine due to transmitted vibration is reduced, and erroneous detection by a knock sensor of the internal combustion engine of transmitted vibration as knocking and the like is suppressed. 
     Also, in the fuel injection valve damping insulator described above, a rigidity of the sleeve may be higher than a rigidity of the coil spring. 
     According to the structure of the fuel injection valve damping insulator described above, excessive deformation that leads to plastic deformation of the coil spring that may deform so much that it may undergo plastic deformation when it receives strong pressing force from the fuel injection valve can be reliably prevented. As a result, the damping characteristic of the damping insulator can be suitably maintained. 
     Also, in the fuel injection valve damping insulator described above, a height of the sleeve and a length of the outer diameter of the small ring portions are set to values at which plastic deformation of the coil spring and the elastic member will not occur with a deformation amount of equal to or less than a difference in length between a height of the sleeve and the outer diameter of the small ring portions before deformation, when the coil spring and the elastic member are deformed. 
     According to the structure of the fuel injection valve damping insulator described above, a height of the sleeve and a length of the outer diameter of the small ring portions are set to values at which plastic deformation of the coil spring and the elastic member will not occur with a deformation amount of equal to or less than the difference in length between a height of the sleeve and the outer diameter of the small ring portions before deformation, when the coil, spring and the elastic member have deformed as a result of receiving strong pressing force from the fuel injection valve, so plastic deformation will not occur if a normal pressing force is applied. Furthermore, if strong pressing force that may cause excessive deformation is applied, the sleeve that has a higher rigidity than the rigidity of the coil spring will receive the pressing force, so the coil spring and the elastic member will not plastic deform. 
     Also, in the fuel injection valve damping insulator described above, the coil spring and the sleeve may be maintained in a state in which the coil spring and the sleeve do not contact each other, and be embedded in the elastic member. 
     According to the structure of the fuel injection valve damping insulator described above, interference by the sleeve with respect to the coil spring is reduced. Accordingly, the possibility that the damping characteristic given to the coil spring will change due to interference by the sleeve is reduced. As a result, the damping characteristic of the damping insulator can be suitably maintained. 
     Also, in the fuel injection valve damping insulator described above, the sleeve may be positioned on an outer peripheral side of the coil spring. 
     According to the structure of the fuel injection valve damping insulator described above, the coil spring can be made smaller. Also, arranging the sleeve on the outside enables the size of the sleeve to be large enough so that it will not fall into the insertion hole of the cylinder head. 
     Also, in the fuel injection valve damping insulator described above, the tolerance ring side of the sleeve may be buried in the elastic member. 
     According to the structure of the fuel injection valve damping insulator described above, the elastic member is interposed between the sleeve and the tolerance ring. As a result, vibration transmitted from the fuel injection valve to the tolerance ring is transmitted to the sleeve after being suppressed by the elastic member. Thus, the transmission of vibration from the sleeve to the internal combustion engine is also suppressed, so the transmission of vibration from the fuel injection valve to the internal combustion engine is able to be suppressed even when the fuel injection valve is supported by the sleeve. 
     Also, in the fuel injection valve damping insulator described above, the shoulder portion side of the sleeve may be buried in the elastic member. 
     According to the structure of the fuel injection valve damping insulator described above, the elastic member is interposed between the sleeve and the shoulder portion. As a result, vibration transmitted from the fuel injection valve to the sleeve is transmitted to the shoulder portion after being suppressed by the elastic member. In this way, the transmission of vibration from the sleeve to the internal combustion engine is suppressed, so the transmission of vibration from the fuel injection valve to the internal combustion engine is able to be suppressed even when the fuel injection valve is supported by the sleeve. 
     Also, in the fuel injection valve damping insulator described above, the damping insulator may also include an annular metal plate interposed between the elastic member and the shoulder portion, and the metal plate may be configured to integrally sandwich the tolerance ring and the elastic member from an inner peripheral side of the tolerance ring. 
     According to the structure of the fuel injection valve damping insulator described above, the relative position, with respect to the elastic member, of the tolerance ring that is not easily strongly joined to the elastic member is determined from the inner peripheral surface by the plate. Accordingly, the tolerance ring is easily stacked appropriately on the elastic member, which enables the operability (i.e., the feasibility) of this kind of damping insulator to be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features, advantages, and technical and industrial significance of this invention will be described in the following detailed description of example embodiments of the invention with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
         FIG. 1  is a view showing a frame format of an overview of a fuel injection apparatus to which a first example embodiment of a damping insulator according to the invention may be applied; 
         FIG. 2  is a plan view of a planar structure of the damping insulator according to this example embodiment; 
         FIG. 3  is a sectional view of a sectional structure taken along line  3 - 3  in  FIG. 2  of the damping insulator according to this example embodiment; 
         FIG. 4  is an end view of an end structure of the damping insulator according to this example embodiment; 
         FIG. 5  is an end view of an end structure of another example embodiment of the damping insulator according to the invention; 
         FIG. 6  is an end view of an end structure of yet another example embodiment of the damping insulator according to the invention; and 
         FIG. 7  is a sectional view of a sectional structure of a damping insulator according to related art. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a first example embodiment of the damping insulator according to the invention will be described with reference to  FIGS. 1 to 4 . As shown in  FIG. 1 , a fuel injection apparatus  10  is provided with a fuel injection valve  11 . A portion toward a tip end (i.e., below in  FIG. 1 ) of the fuel injection valve  11  is supported by being inserted through an insertion hole  15  of a cylinder head  12 , and a portion toward a base end (i.e., above in  FIG. 1 ) of the fuel injection valve  11  is supported by a fuel injection valve cup  14  of a delivery pipe  13 . In this way, the fuel injection valve  11  is suspended between the cylinder head  12  and the delivery pipe  13 . 
     The insertion hole  15  of the cylinder head  12  is formed extending through from an outer surface  12 A of the cylinder head  12  to an inner surface  12 B of the cylinder head  12 , as a multi-stepped hole having a hole diameter that becomes successively narrower from the outer surface  12 A of the cylinder head  12  (i.e., the upper side in  FIG. 1 ) toward the inner surface  12 B (i.e., the lower side in  FIG. 1 ) that faces a combustion chamber of an in-cylinder injection type internal combustion engine. That is, the hole diameter of an inlet portion  17  of the insertion hole  15 , that is an inlet that opens to the outer surface  12 A of the cylinder head  12 , is largest, and the hole diameter of a tip end hole portion  16  of the insertion hole  15  that opens to the inner surface  12 B is smallest. As a result, a stepped portion based on the difference of these hole diameters is formed at the portion where the diameter of the insertion hole  15  changes, so a shoulder portion  18  as the stepped portion is formed between the inlet portion  17  and a mid-hole portion  19  that is connected to the inlet portion  17 . That is, the shoulder portion  18  is formed in a way that makes an end portion on the outer surface  12 A side of the mid-hole portion  19  widen out in an annular shape. The tip end hole portion  16  of the insertion hole  15  is communicated with an in-cylinder injection type combustion chamber, so an injection nozzle  23  of the fuel injection valve  11  is able to be inserted and fit into the tip end hole portion  16  of the insertion hole  15 . As a result, the tip end hole portion  16  introduces high-pressure fuel injected from the injection nozzle  23  into the combustion chamber. 
     The delivery pipe  13  is designed to supply high-pressure fuel, of which the pressure had been accumulated to an injection pressure, to the fuel injection valve  11 , so the delivery pipe  13  has the fuel injection valve cup  14  into which a base end portion of the fuel injection valve  11  is inserted and fit. When the base end portion of the fuel injection valve  11  is inserted into the fuel injection valve cup  14 , a fuel seal between the base end portion of the fuel injection valve  11  and an inner peripheral surface  14 A of the fuel injection valve cup  14  is ensured by an O-ring  29  arranged between the two. 
     The fuel injection valve  11  is designed to inject, at a predetermined timing, the high-pressure fuel supplied from the delivery pipe  13  into the combustion chamber that is formed by the cylinder head  12 . A housing of the fuel injection valve  11  is formed in a multi-stepped cylindrical shape that becomes successively narrower from the center in the axial direction toward both the tip end side (i.e., the insertion hole  15  side) and the base end side (i.e., the fuel injection valve cup  14  side). 
     That is, the center of the housing of the fuel injection valve  11  is a large diameter portion  20 , and the housing of the fuel injection valve  11  has, in order from the large diameter portion  20  toward the base end, a base end middle portion  26  that has a smaller diameter than the large diameter portion  20 , a base end inserting portion  27  that has a smaller diameter than the base end middle portion  26 , and a base end sealing portion  28  that has a smaller diameter than the base end inserting portion  27 . A connector  26 J that is connected to wiring for transmitting drive signals to an electromagnetic valve or the like housed in the fuel injection valve  11  in order to control fuel injection is provided on the base end middle portion  26 . The base end sealing portion  28  supports the O-ring  29  through which it is inserted. 
     The O-ring  29  is formed in a generally toric (i.e., annular) shape by an elastic member such as rubber that is resistant to fuel. The O-ring  29  is also pressure resistant to the high-pressure fuel pressure. The inner periphery of the O-ring  29  closely contacts the outer peripheral surface of the base end sealing portion  28 . Therefore, a seal that prevents high-pressure fuel from leaking between the fuel injection valve  11  and the O-ring  29  is obtained by the close contact between the inner periphery of the O-ring  29  and the outer peripheral surface of the base end sealing portion  28 . Also, the outer periphery of the O-ring  29  is formed of a size so that it closely contacts the inner peripheral surface  14 A of the fuel injection valve cup  14  of the delivery pipe  13 . As a result, when the base end portion of the fuel injection valve  11  is inserted into the fuel injection valve cup  14  of the delivery pipe  13 , the outer periphery of the O-ring  29  of the fuel injection valve  11  closely contacts the inner peripheral surface  14 A of the fuel injection valve cup  14 , thus providing a seal against high-pressure fuel. In this way, a fuel seal against the high-pressure fuel is able to be ensured between the fuel injection valve  11  and the fuel injection valve cup  14 , by the seal between the O-ring  29  and the outer peripheral surface of the base end sealing portion  28 , and the seal between the O-ring  29  and the inner peripheral surface  14 A of the fuel injection valve cup  14 . 
     Moreover, the housing of the fuel injection valve  11  also has, in order from the large diameter portion  20  toward the tip end, a medium diameter portion  21  that has a smaller diameter than the large diameter portion  20 , and a small diameter portion  22  that has a smaller diameter than the medium diameter portion  21 . The injection nozzle  23  that injects fuel is provided on the tip end of the small diameter portion  22 . A seal portion  25  for maintaining the airtightness of the combustion chamber by ensuring a seal with the wall surface of the insertion hole  15  is provided to the base end side of the injection nozzle  23  on the small diameter portion  22 . 
     A stepped portion based on the difference between the outer diameter of the large diameter portion  20  and the outer diameter of the medium diameter portion  21  is formed between the large diameter portion  20  and the medium diameter portion  21 . A tapered surface  24  that is drawn (i.e., becomes narrower) toward the tip end side is provided on this stepped portion. That is, the tapered surface  24  of the fuel injection valve  11  faces, with a predetermined slant, the shoulder portion  18  positioned at the inlet portion  17  of the insertion hole  15  of the cylinder head  12  when the fuel injection valve  11  is inserted into the insertion hole  15 . The angle of the tapered surface  24  with respect to a central axis (axis C) of the fuel injection valve  11  is, when represented as an angle with respect to an axis-parallel line C 1  that is parallel to the axis C, preferably between 30° and 60°, inclusive, but may be selected from values greater than 0° and less than 90°. 
     An annular damping insulator  30  is provided between the tapered surface  24  of the fuel injection valve  11  and the shoulder portion  18  of the insertion hole  15 . This damping insulator  30  is designed to absorb and suppress vibration that occurs in the fuel injection valve  11  based on fuel pressure fluctuation when there are fluctuations in the pressure of fuel supplied via the delivery pipe  13  due to fuel injection by the fuel injection valve  11  being started and stopped. 
     As shown in  FIGS. 2 and 3 , the damping insulator  30  has a toric (i.e., annular) shape with an outer diameter Ra and an inner diameter Rb. The outer diameter Ra of the damping insulator  30  is formed of a size that enables the damping insulator  30  to sit on the annular shoulder portion  18 . Also, the inner diameter Rb of the damping insulator  30  is formed of a size that allows the medium diameter portion  21  of the fuel injection valve  11  to fit through the damping insulator  30  with some play between it and the damping insulator  30 . As shown in  FIG. 1 , a ring  21 R that has an outer diameter that is larger than the inner diameter Rb of the damping insulator  30  is provided on a tip end side portion of the fuel injection valve  11  of the medium diameter portion  21 . The damping insulator  30  with the medium diameter portion  21  fit through it, is prevented from separating from the medium diameter portion  21  of the fuel injection valve  11  by this ring  21 R. 
     As shown in  FIG. 3 , the damping insulator  30  includes an annular damping member  31 , an annular plate  32  formed with a channel-shaped cross section so as to wrap around an inner peripheral portion (i.e., the axis C side in  FIG. 3 ) and a lower portion (i.e., the lower side in  FIG. 3 ) of the damping member  31 , and an annular tolerance ring  33  provided on an upper portion (i.e., the upper side in  FIG. 3 ) of the damping member  31 . That is, the plate  32  has a plate bottom portion  37  on which the damping member  31  is stacked, and the tolerance ring  33  is further stacked on top of the damping member  31 . 
     As shown in  FIG. 4 , the damping member  31  is a member for absorbing and suppressing vibration of the fuel injection valve  11 , and includes an annular coil spring  34 , an annular sleeve  35  arranged to the outer peripheral side of the coil spring  34 , and an elastic member  36  formed in an annular shape from rubber or the like in which the coil spring  34  and the annular sleeve  35  are integrally embedded. That is, the coil spring  34  is formed in the shape of a long helix-shaped body formed in a circle, curving so as to surround the fuel injection valve  11 .  FIG. 4  is a view showing one turn of the helix as a small ring portion of the coil spring  34 . The helix of the coil spring  34  is formed by many of these turns being continuously connected together.  FIG. 4  also shows a height H 1  that is the helix diameter (i.e., the outer diameter of one turn) of the helix of the coil spring  34 , and a width W 2  that is the helix diameter (i.e., the outer diameter of one turn) of the helix. When the coil spring  34  is not being pressed on, the height H 1  and the width W 2  are approximately the same length, but when the coil spring  34  is pressed on in the vertical direction, the ring shape of the turn of the helix deforms such that the height becomes lower than the height H 1  and the width becomes wider than the width W 2 , i.e., H 1 &lt;W 2 . The coil spring  34  is made with stainless steel or spring steel typified by piano siring as the material. 
     With the main raw material of the elastic member  36  being fluoro-rubber, nitrile rubber, hydrogenated nitrile rubber, fluorosilicone rubber, or acrylic rubber, a filler such as carbon black, silica, clay, calcium carbonate or celite, and rubber that is a blend of an antioxidant, a processing aid, and a curing agent suitable for each rubber, or an elastomer such as TPE, or the like, is used as the material of the elastic member  36 . The coil spring  34  is embedded inside the elastic member  36 , so the height in the vertical direction is the height H 1  that is the same as the height of the coil spring  34 , and the width in the radial direction is a width W 1  that includes the width W 2  of the coil spring  34  and is wider than this width W 2 . 
     The sleeve  35  is more rigid than the coil spring  34 , and is made from metal including iron and stainless steel and the like, or engineering plastic that is very rigid, for example. The sleeve  35  is formed in an annular shape and has a thickness of a width W 3  in the width direction (i.e., the radial direction). The inner diameter of the sleeve  35  is large enough so that the sleeve  35  does not contact the coil spring  34  that is arranged on the inner peripheral side of the sleeve  35 . Therefore, a gap W 4  that is filled with the elastic member  36  is provided in the width direction (i.e., the radial direction) between the sleeve  35  and the coil spring  34 . That is, the sleeve  35  is configured so as not to contact the coil spring  34 . This reduces the possibility, of the vibration absorbing and damping characteristic of the coil spring  34  changing due to the coil spring  34  abutting against the sleeve  35 . Thus, the damping member  31  is also able to have a good vibration absorbing and damping characteristic that is little affected by the sleeve  35 . Also, the outer peripheral side of the sleeve  35  is covered by the elastic member  36  of a width W 5  in the circumferential direction (i.e., the radial direction). 
     The sleeve  35  is such that a height H 2  thereof is formed lower than an outer diameter (i.e., the height H 1 ) of the helix diameter of a cross-section of the coil spring  34  (i.e., H 2 &lt;H 1 ), and the lower end in the vertical direction is aligned with the height of the lower end of the helix diameter of the coil spring  34 . Therefore, a height H 3  (=H 1 −H 2 ) is provided between the sleeve  35  and the coil spring  34  on the upper side in the vertical direction, and the elastic member  36  of the height H 3  is filled on the upper side of the sleeve  35  that is embedded in the elastic member  36 . That is, the upper end side in the vertical direction of the sleeve  35  is buried in the elastic member  36 . As a result, when the damping member  31  and the tolerance ring  33  are joined, the elastic member  36  of a thickness corresponding to the height H 3  is arranged (i.e., interposed) between the upper side of the sleeve  35  and a ring bottom surface  40  of the tolerance ring  33 . 
     In this way, the damping member  31  is given a characteristic suitable for absorbing and damping vibration in the fuel injection valve  11 , based on the vibration absorbing and damping characteristic of the elastic member  36  and the vibration absorbing and damping characteristic of the coil spring  34 . 
     The elastic member  36  and the coil spring  34  display a suitable vibration absorbing and damping characteristic by appropriate elastic deformation when a prescribed load at which elasticity can be maintained is applied. However, if a load that exceeds this prescribed load is applied, plastic deformation will occur and elasticity will be lost, resulting in the elastic member  36  and the coil spring  34  no longer being able to appropriately display the vibration absorbing and damping characteristic. That is, if the elastic member  36  and the coil spring  34  deform in a way in which they are crushed in the vertical direction by the pressing force of the fuel injection valve  11 , the elastic member  36  and the coil spring  34  will freely deform while the deformation amount is equal to or less than a predetermined deformation amount, but if they deform beyond the predetermined deformation amount, the elastic member  36  and the coil spring  34  will end up plastic deforming. For example, even if a large pressing force is applied such that the height of the damping member  31  deforms from the height H 1  to the height H 2 , appropriate elastic deformation of the damping member  31  will be maintained. That is, the predetermined deformation amount indicative of the boundary between elastic deformation and plastic deformation of the damping member  31  is the height H 3 . However, if the deformation amount exceeds the height H 3  due to pressing force that exceeds the predetermined pressing force, such that the height of the damping member  31  deforms to become lower than the height H 2 , it is more likely that the appropriate elastic deformation will not be able to be maintained and the damping member  31  will end up plastic deforming. 
     Therefore, in this example embodiment, even if a load that exceeds a predetermined load is applied, the sleeve  35  will prevent the elastic member  36  and the coil spring  34  from excessively deforming, beyond the predetermined deformation amount (i.e., the height H 3 ). That is, if the elastic member  36  and the coil spring  34  deform in a way in which they are crushed in the vertical direction by the pressing force of the fuel injection valve  11 , the elastic member  36  and the coil spring  34  will deform freely while the deformation amount is equal to or less than the predetermined deformation amount. If a load that exceeds this predetermined deformation amount is applied or the like due to excessive pressing force or the like, the sleeve  35  will prevent deformation that exceeds the predetermined deformation amount of the elastic member  36  and the coil spring  34 . Therefore, even if a large pressure is suddenly applied to the damping member  31 , plastic deformation of the elastic member  36  and the coil spring  34  is prevented by the sleeve  35 , so the elastic force of the elastic member  36  and the coil spring  34  can be maintained. 
     When the sleeve  35  prevents excessive deformation of the elastic member  36  and the coil spring  34 , the sleeve  35  supports the vibration and the pressing force from the tolerance ring  33 . At this time, the elastic member  36  that is arranged at the height H 3  between the sleeve  35  and the tolerance ring  33  continues to be interposed as it is deformed. Therefore, the sleeve  35  and the tolerance ring  33  are prevented from directly contacting one another, so vibration transmitted from the tolerance ring  33  to the sleeve  35  is suppressed compared with when the sleeve  35  and the tolerance ring  33  directly contact one another. 
     The plate  32  is made of metal such as SUS430 that is stainless material that is easy to draw, for example. As shown in  FIG. 4 , the plate  32  is formed with a channel-shaped cross section, and includes the plate bottom portion  37 , a plate inner wall portion  38  that extends from an inner peripheral side of the plate bottom portion  37  upward along the damping member  31 , and a plate covering portion  39  that is bent from an upper end of the plate inner wall portion  38  toward the outer peripheral side so as to cover a portion of the inner peripheral portion of the tolerance ring  33 . That is, the plate  32  integrally sandwiches the tolerance ring  33  and the damping member  31  from the inner peripheral side of the tolerance ring  33 . 
     The damping member  31  contacts (i.e., presses against) the upper surface of the plate bottom portion  37 , while the lower surface of the plate bottom portion  37  is abutted against the shoulder portion  18  of the insertion hole  15 . As a result, the plate  32  maintains the ability to suitably slide in the cross direction with respect to the shoulder portion  18  of the insertion hole  15 , while force from the damping member  31  and the like that is received by the plate  32  is distributed evenly to the annular shoulder portion  18 . The shoulder portion  18  is part of the cylinder head  12  that is made of aluminum or the like, so the hardness of the shoulder portion  18  is less than that of the coil spring  34 . Therefore, if the coil spring  34  were to directly contact the shoulder portion  18 , it is possible that it may cause problems such as the portion of the shoulder portion  18  where the force is concentrated becoming chipped or deformed. However, in this example embodiment, the force from the coil spring  34  that is received by the plate  32  is dispersed and transmitted in the circumferential direction to the shoulder portion  18  via the annular plate bottom portion  37  that corresponds to the shoulder portion  18 . Accordingly, the plate  32  prevents problems that may occur if the coil spring  34  directly contacts the shoulder portion  18 . 
     A return portion  37 R formed by press forming is formed on an end portion on the outer peripheral side of the plate bottom portion  37 . That is, the return portion  37 R is cut up at an angle toward the outer peripheral side from the bottom surface of the plate bottom portion  37 . The damping insulator  30  is able to slide on the shoulder portion  18  and move to the outer peripheral surface of the inlet portion  17  from a position near the center of the step of the shoulder portion  18  that is distanced from the outer peripheral surface of the inlet portion  17 . At this time, the plate bottom portion  37  of the damping insulator  30  will not catch or ride up on a portion that has been left rising up on the outer peripheral end of the shoulder portion  18  because the return portion  37 R is provided. That is, the return portion  37 R is formed in a shape such that it will not contact the portion that is left rising up on the outer peripheral end of the shoulder portion  18 . A rise on the outer peripheral end of the shoulder portion  18  that is made so that the return portion  37 R will not contact it may also be intentionally formed. 
     This kind of return portion  37 R prevents the outer peripheral end of the plate bottom portion  37  from interfering with the portion that rises up on the outer peripheral end of the shoulder portion  18 , even if the damping insulator  30  moves to abut against the outer periphery of the shoulder portion  18 . That is, the return portion  37 R prevents the movement characteristic of the plate  32  from decreasing due to the plate bottom portion  37  catching on the rising portion of the outer peripheral end of the shoulder portion  18 . Furthermore, the return portion  37 R prevents the position where the tolerance ring  33  abuts against the tapered surface  24  of the fuel injection valve  11  (i.e., the position of a height Hi from the shoulder portion  18  in  FIG. 4 ) from changing due to the plate bottom portion  37  riding up on the rising portion and tilting. 
     The plate inner wall portion  38  is formed so as to rise up along the damping member  31  from the inner peripheral end of the plate bottom portion  37 , and thus extends upward in a manner following the medium diameter portion  21  of the fuel injection valve  11 . 
     The plate covering portion  39  extends such that the tip end portion of the plate inner wall portion  38  partially covers an inner peripheral slanted surface  42  of the tolerance ring  33  that is stacked on the damping member  31 . Furthermore, the plate covering portion  39  abuts against the inner peripheral slanted surface  42  of the tolerance ring  33 , and applies an outer peripheral side and downward force to the inner peripheral slanted surface  42 . As a result, the plate covering portion  39  reinforces the connection between the tolerance ring  33  and the damping member  31 , and prevents the relative position between the tolerance ring  33  and the damping member  31  from changing. 
     The tolerance ring  33  supports the fuel injection valve  11  with respect to the cylinder head  12 , by abutting against the tapered surface  24  of the fuel injection valve  11 . The tolerance ring  33  is made of metal such as stainless steel, e.g., SUS304 that is hard stainless material. The metal of which the tolerance ring  33  is made has a hardness equal to that of the tapered surface  24  of the fuel injection valve  11 , but metal having a hardness equal to that of a member having another hardness, such as the coil spring  34 , may also be used. 
     As shown in  FIG. 4 , the cross-section of the tolerance ring  33  has the generally trapezoidal shape of a chock block. That is, the tolerance ring  33  has the ring bottom surface  40  that is connected to the damping member  31 , a ring outer peripheral surface  41  that is perpendicular to the ring bottom surface  40  on the outer periphery of the ring, a horizontal ring upper surface  46  from an upper end of the ring outer peripheral surface  41  toward the center of the ring, and the inner peripheral slanted surface  42  that forms a concave taper from the inner peripheral edge of the ring upper surface  46  toward the center of the ring. More specifically, the length of the ring upper surface  46  is shorter than the length of the ring bottom surface  40  in the radial direction, so the inner peripheral slanted surface  42  that connects the inner peripheral edge of the ring bottom surface  40  with the inner peripheral edge of the ring upper surface  46  forms a concave taper toward the center of the ring. The inner peripheral slanted surface  42  includes a connecting portion  43  and a tapered surface  45 . 
     The ring bottom surface  40  abuts against the upper surface of the damping member  31 . The ring bottom surface  40  disperses the pressing force from the fuel injection valve  11  that is received by the tolerance ring  33  in the circumferential direction along the entire annular ring bottom surface  40  and transmits that pressing force to the upper surface of the damping member  31 , such that the pressing force is applied evenly to the damping member  31 . As a result, problems such as the damping member  31  plastic deforming due to localized concentration of force are prevented from occurring. 
     The outer diameter of the ring outer peripheral surface  41  is formed to be substantially the same diameter as the outer diameter of the damping member  31 , and the outer diameter Ra of the plate bottom portion  37  of the plate  32 . That is, the outer diameter of the ring outer, peripheral surface  41  is set to be substantially the same as the outer diameter Ra of the damping insulator  30 , so it will not constrict the movement range in the radial direction of the damping insulator  30  at the inlet portion  17  of the insertion hole  15 . The height of the ring outer peripheral surface  41  is set to a height that is able to support the fuel injection valve  11  at a height Hi prescribed in advance as the distance from the shoulder portion  18  as the height at which to support the fuel injection valve  11 . That is, the height from the shoulder portion  18  to the ring upper surface  46  that extends horizontally from the upper end of the ring outer peripheral surface  41  is also the height Hi. 
     The inner peripheral slanted surface  42  is provided between the inner peripheral edge of the ring bottom surface  40  and the inner peripheral edge of the ring upper surface  46 . The connecting portion  43  is positioned on the inner side of the inner peripheral slanted surface  42  and abuts against the plate covering portion  39  of the plate  32 . The tapered surface  45  is positioned on the outer side of the inner peripheral slanted surface  42  and faces the tapered surface  24  of the fuel injection valve  11 . The tapered surface  45  and the ring upper surface  46  form an abutting portion  44  that faces the tapered surface  24  of the fuel injection valve  11 . That is, the tapered surface  45  is a further tapered surface of the tolerance ring  33 . Also, the connecting portion  43  is positioned to the inner peripheral side of the abutting portion  44 , and a large portion of the connecting portion  43  does not face the tapered surface  24  of the fuel injection valve  11 . More specifically, the inner peripheral edge of the connecting portion  43  is connected, via the inner peripheral surface of the tolerance ring  33 , to the inner peripheral edge of the ring bottom surface  40 . The plate covering portion  39  of the plate  32  is bent toward the outer peripheral side so as to abut against this connecting portion  43 . That is, force to the outer peripheral side and downward (i.e., in the direction of the damping member  31 ) is applied from the plate covering portion  39  to the connecting portion  43 . Therefore, the pressure contact of the tolerance ring  33  against the damping member  31  is reinforced, so the relative positional relationship with the damping member  31  is kept from changing. 
     A ridge line  47  (an apex in a sectional view) is formed at the connecting portion between the outer peripheral edge of the tapered surface  45  and the inner peripheral edge of the ring upper surface  46 . An angle β 1  of the tapered surface  45  is set smaller than an angle α of the tapered surface  24  of the fuel injection valve  11 . An angle β 12  of the ring upper surface  46  with respect to the axis-parallel line C 1  is set larger than the angle α of the tapered surface  24 , to a substantially right angle. Accordingly, the angle (i.e., the taper angle) β 1  of the tapered surface  45  and the angle (i.e., the taper angle) β 12  of the ring upper surface  46  are both different angles than the angle (i.e., the taper angle) α of the tapered surface  24  of the fuel injection valve  11 , and the angle α is included between these angles β 1  and β 12  (β 1 &lt;α&lt;β 12 ). Therefore, the ridge line  47  that serves as the boundary line between the tapered surface  45  and the ring upper surface  46  appears as an apex that makes point contact with the tapered surface  24  of the fuel injection valve  11 , so actually the ridge line  47  makes line contact with the tapered surface  24  of the fuel injection valve  11 . Meanwhile, from this, the inner peripheral surface of the tolerance ring  33 , the ring bottom surface  40 , and the ring outer peripheral surface  41 , that are all surfaces of the tolerance ring  33 , form surfaces that do not face the tapered surface  24  of the fuel injection valve  11 . 
     [Operation of the Damping Insulator] 
     With the damping insulator of this example embodiment, when pressing force is applied from the tapered surface  24  of the fuel injection valve  11 , force in the direction along the axis-parallel line C 1  (i.e., an axial component force of a load, i.e., an axial load) according to the angle α of the tapered surface  24  is applied to the ridge line  47  of the tolerance ring  33 . The force in the direction along the axis-parallel line C 1  is transmitted to the shoulder portion  18  via the damping member  31  and the plate  32 . As a result, the fuel injection valve  11  enters the insertion hole  15  of the cylinder head  12  in response to the damping member  31  being press deformed by the pressing force from the fuel injection valve  11 . In other words, the fuel injection valve  11  moves farther toward the tip end of (i.e., downward with respect to) the cylinder head  12 , such that the height at which the fuel injection valve  11  is supported by the cylinder head  12  decreases, instead of being maintained at the height Hi. 
     However, the sleeve  35  of height H 2  is embedded in the damping member  31 , so the height of the damping member  31  will not become lower than the height H 2 . That is, the height at which the fuel injection valve  11  is supported by the cylinder head  12  is maintained higher than the difference of the height Hi minus the height  13 . Also, the height H 2  is a height that ensures a deformation amount of equal to or less than a predetermined deformation amount that enables the elastic deformation of the damping member  31  to be maintained. Thus, the sleeve  35  eliminates the possibility of the damping characteristic of the damping member  31  decreasing or the damping member  31  plastic deforming due to the damping member  31  deforming to a height that is lower than the height H 2 . As a result, the sleeve  35  restricts the deformation of the damping member  31  to between the height H 1  and the height H 2 , and ensures that the damping member  31  suitably displays damping performance. 
     Also, even if the damping member  31  approaches the height H 2 , the elastic member  36  is interposed, even as it deforms, between the sleeve  35  and the tolerance ring  33 . As a result, vibration of the fuel injection valve  11  that is transmitted from the tolerance ring  33  to the sleeve  35  is also suppressed to some degree by the elastic member  36  that is interposed. That is, the possibility that vibration of the fuel injection valve  11  will result in abnormal noise emanating from the internal combustion engine, or cause a knock sensor of the internal combustion engine to malfunction is minimized. 
     Furthermore, the inner peripheral surface of the sleeve  35  will not contact the coil spring  34  even if the coil spring  34  is pressed to the height H 2 . Therefore, the possibility of the vibration absorbing and damping characteristic of the coil spring  34  changing due to the coil spring  34  contacting the sleeve  35  is eliminated. Thus, the damping member  31  is able to display a suitable vibration absorbing and damping characteristic with little effect from the sleeve  35 . 
     Also, when the damping member  31  approaches the height H 2 , the sleeve  35  transmits the pressing force of the fuel injection valve  11  to the shoulder portion  18  of the insertion hole  15  via the upper surface of the plate bottom portion  37 . Therefore, the ability of the plate  32  to suitably slide in the cross direction with respect to the shoulder portion  18  of the insertion hole  15  is maintained, and the pressing force of the sleeve  35  is distributed evenly to the shoulder portion  18  via the plate  32 . As a result, problems such as the shoulder portion  18  becoming chipped or deformed due to the sleeve  35  that has a higher hardness than the shoulder portion  18  directly contacting the shoulder portion  18  that is made of aluminum or the like as part of the cylinder head  12  will not occur. 
     As described above, the damping insulator of this example embodiment is able to yield the effects listed below. 
     (1) The coil spring  34  may also largely deform from pressure or the like, such that the position of the fuel injection valve  11  is maintained by the sleeve  35 . At this time, at least one of the tolerance ring  33  side and the shoulder portion  18  side of the sleeve  35  is buried in the elastic member  36 , so the elastic member  36  is interposed together with the sleeve  35  between the fuel injection valve  11  and the cylinder head  12 . As a result, vibration transmitted from the fuel injection valve  11  to the cylinder head  12  via the sleeve  35  can be reduced by the elastic member  36  that is interposed midway along this path. That is, even if the coil spring  34  largely deforms, the position of the fuel injection valve  11  is able to be maintained by the sleeve  35 , and vibration transmitted to the internal combustion engine is also able to be suppressed. As a result, even when the position of the fuel injection valve  11  is maintained by the sleeve  35 , vibration transmitted from the fuel injection valve  11  to the internal combustion engine is suppressed, so noise that emanates from the internal combustion engine due to transmitted vibration is reduced, and erroneous detection by a knock sensor of the internal combustion engine of transmitted vibration as knocking and the like is suppressed. 
     (2) Excessive deformation that leads to plastic deformation of the coil spring  34  that may deform so much that it may undergo plastic deformation when it receives strong pressing force from the fuel injection valve  11  can be reliably prevented. As a result, the damping characteristic of the damping insulator  30  can be suitably maintained. 
     (3) The coil spring  34  and the sleeve  35  are maintained in a state in which they do not contact each other, so interference by the sleeve  35  with respect to the coil spring  34  is reduced. Accordingly, the possibility that the damping characteristic given to the coil spring  34  will change due to interference by the sleeve  35  is reduced. As a result, the damping characteristic of the damping insulator  30  can be suitably maintained. 
     (4) Positioning the sleeve  35  on the outer peripheral side of the coil spring  34  enables the coil spring  34  to be made smaller. Also, arranging the sleeve  35  on the outside enables the size of the sleeve  35  to be large enough so that it will not fall into the insertion hole of the cylinder head  12 . 
     (5) The tolerance ring  33  side of the sleeve  35  is buried in the elastic member  36 , so the elastic member  36  is interposed between the sleeve  35  and the tolerance ring  33 . As a result, vibration transmitted from the fuel injection valve  11  to the tolerance ring  33  is transmitted to the sleeve  35  after being suppressed by the elastic member  36 . Thus, the transmission of vibration from the sleeve  35  to the internal combustion engine is also suppressed, so the transmission of vibration from the fuel injection valve  11  to the internal combustion engine is able to be suppressed even when the fuel injection valve  11  is supported by the sleeve  35 . 
     (6) The tolerance ring  33  and the elastic member  36  are integrally sandwiched by the plate  32 , so the relative position, with respect to the elastic member  36 , of the tolerance ring  33  that is not easily strongly joined to the elastic member  36  is determined from the inner peripheral surface by the plate  32 . Accordingly, the tolerance ring  33  is easily stacked appropriately on the elastic member  36 , which enables the operability (i.e., the feasibility) of this kind of damping insulator  30  to be improved. 
     Next, other example embodiments other than the example embodiment described above will be described. The invention may also be carried out by example embodiments such as those described below, for example.
         In the example embodiment described above, a case is described in which the elastic member  36  is interposed between the ring bottom surface  40  and the sleeve  35 . However, the invention is not limited to this. That is, the elastic member may also be interposed between the sleeve and the plate bottom portion. For example, as shown in  FIG. 5 , the elastic member  36  of the height H 3  may be interposed between the sleeve  35  and the plate bottom portion  37 , by aligning the height of the upper end of the coil spring  34  of the height H 1  with the height of the upper end of the sleeve  35  of the height H 2 . That is, the lower end side in the vertical direction of the sleeve  35  may be buried in the elastic member  36 . This also enables vibration transmitted from the sleeve  35  to the shoulder portion  18  via the plate bottom portion  37  to be suppressed by the elastic member  36  between the sleeve  35  add the plate bottom portion  37 , even if the height of the damping member  31  deforms so as to approach the height H 2 . As a result, the degree of freedom in the structure of the damping insulator is able to be increased.   Also, the elastic member may be interposed both between the ring bottom surface and the sleeve, and between the sleeve and the plate bottom surface. For example, as shown in  FIG. 6 , the elastic member  36  of a height H 32  may be interposed between the ring bottom surface  40  and the sleeve  35 , and the elastic member  36  of a height H 33  may be interposed between the sleeve  35  and the plate bottom portion  37 , by aligning an intermediate position in the vertical direction of the coil spring  34  of the height H 1  with an intermediate position in the vertical direction of the sleeve  35  of the height H 2 . That is, the lower end side and the upper end side in the vertical direction of the sleeve  35  may both be buried in the elastic member  36 . This also enables vibration transmitted from the ring bottom surface  40  to the shoulder portion  18  to be suppressed by the elastic members  36  between the ring bottom surface  40  and the sleeve  35 , and between the sleeve  35  and the plate bottom portion  37 , even if the height of the damping member  31  deforms so as to approach the height H 2 . As a result, the degree of freedom in the structure of the damping insulator is able to be increased.   In the example embodiment described above, a case is described in which the inlet portion  17  is formed the required minimum size for the damping insulator  30  to move for axial compensation. However, the invention is not limited to this. That is, the inlet portion may also be formed larger than the required minimum size for the damping insulator to move for axial compensation.   In the example embodiment described above, a case is described in which the angle β 12  of the ring upper surface  46  is an angle that is substantially a right angle (i.e., 90°) with respect to the axis-parallel line C 1 . However, the invention is not limited to this. That is, the angle of the ring upper surface may also be an angle that is less than 90° with respect to the axis-parallel line C 1 . This also enables a ridge line to be formed by the ring upper surface and the tapered surface. As a result, the degree of design freedom for the tapered surface and the ring upper surface is increased, and the degree of design freedom for the ridge line is also increased. Hence, the degree of design freedom for this kind of damping insulator is able to be increased.   The various heights H 1  to H 3  in the example embodiment described above may be set as stated below. For example, the height H 1  of the damping member  31  (i.e., the elastic member  36 ) may be set to 1.75 mm, the height H 2  of the sleeve  35  may be set to 1.6 mm, and the height H 3  at which the elastic member  36  is interposed may be set at 0.15 mm. The height H 3  may also be adjusted to be 0.15 mm±0.1. This kind of adjustment also applies to the other heights. In this way, the height H 3  at which the elastic member is interposed need simply be equal to or less than ¼ of the height H 1  of the damping member, and more preferably, equal to or less than 1/10 of the height H 1  of the damping member.   In the example embodiment described above, a case is described in which the sleeve  35  is arranged on the outer peripheral side of the coil spring  34 , but the invention is not limited to this. That is, the sleeve may also be arranged on the inner peripheral side of the coil spring. Therefore, the degree of design freedom for the damping insulator is able to be increased.   In the example embodiment described above, a case is described in which the coil spring  34  and the sleeve  35  are distanced from one another, but the invention is not limited to this. That is, the coil spring may also be contacting the sleeve, or able to contact the sleeve.   In the example embodiment described above, a case is described in which the plate bottom portion  37  is provided between the damping member  31  and the shoulder portion  18 , but the invention is not limited to this. That is, as long as the fuel injection valve is able to be suitably supported with respect to the shoulder portion, the plate bottom portion does not have to be provided between the damping member and the shoulder portion. Therefore, the degree of design freedom for the damping insulator is able to be increased.   The internal combustion engine to which the invention may be applied may be a gasoline engine or a diesel engine, as long as it is an in-cylinder injection type internal combustion engine.