Abstract:
The objective of the present invention is to provide a diaphragm damper with which the amount of volume change due to the resonance frequency and pressure can be set freely and the performance of the diaphragm damper can be optimized, without changing the attachment structure for a conventional metal diaphragm and without obstructing the space where fuel flows in a fuel chamber. To this end, this diaphragm damper, wherein a high-pressure gas is enclosed in a high-pressure chamber formed by two disk-shaped metal diaphragms the outer circumferential portions of which have been joined together, is constructed such that rubber-like elastic members are arranged within the high-pressure chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a 371 U.S. National Stage Application of International Application No. PCT/JP2013/076930, filed on Oct. 3, 2013, and published in Japanese as WO 2014/054727 A1 on Apr. 10, 2014. This application claims priority to Japanese Application No. 2013-129369, filed on Jun. 20, 2013 and Japanese Application No. 2012-221811, filed on Oct. 4, 2012. The entire disclosures of the above applications are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a diaphragm damper. 
         [0004]    Further, the present invention relates to a diaphragm damper which is used for reducing pulsation generated in a high-pressure pump used in an engine. 
         [0005]    2. Description of the Conventional Art 
         [0006]    There has been conventionally known a high-pressure pump which pressurizes fuel supplied from a fuel tank on the basis of a reciprocating movement of a plunger so as to pressure feed to an injector side. 
         [0007]    In this kind of high-pressure pump, a fuel chamber is formed in a fuel inlet side, and the fuel is pressurized and discharged by repeating “suction stroke” which sucks the fuel from the fuel chamber to a pressurizing chamber when a plunger moves down, “metering stroke” which returns a part of the fuel in the pressurizing chamber to the fuel chamber when the plunger moves up, and “pressurizing stroke” which pressurizes the fuel when the plunger further moves up after a suction valve is closed. 
         [0008]    The high-pressure pump mentioned above has a diaphragm damper for reducing the pulsation generated in the fuel chamber built-in. 
         [0009]    Further, the high-pressure pump is variously designed to enhance an effect of reducing the pulsation in the diaphragm. 
         [0010]    For example, Japanese Unexamined Patent Publication No. 2004-138071 discloses a device which employs an elastic member for a support member supporting a metal diaphragm constructing a diaphragm damper (Japanese Unexamined Patent Publication No. 2004-138071). 
         [0011]    However, in the device described in Japanese Unexamined Patent Publication No. 2004-138071, since the elastic member pinches the metal diaphragm from both upper and lower side directions, a space occupied by the elastic member becomes large, thereby blocking a space in which the fuel flows within the fuel chamber. 
         [0012]    Therefore, an amount of the fuel which can be sucked into the fuel chamber is reduced, and there is a risk that the effect of reducing the pulsation by the diaphragm can not be sufficiently obtained. 
         [0013]    Further, parts of the high-pressure pump oscillate on the basis of an operation of a suction valve, a plunger and a discharge valve, at the driving time of the high-pressure pump. 
         [0014]    The oscillation is transmitted to the fuel, and is transmitted as the pulsation to a piping which is connected to the high-pressure pump, and there is a problem that an abnormal noise is generated due to resonance of the oscillation. 
         [0015]    Consequently, there has been proposed a diaphragm damper which is structured such as to support an outer peripheral portion of the metal diaphragm by a rubber-like elastic member and a wave washer (a pressing member) (Japanese Unexamined Patent Publication No. 2012-132400). 
         [0016]    However, since the diaphragm damper is structured such as to elastically support the outer peripheral portion of the metal diaphragm by the rubber-like elastic member and the wave washer (the pressing member), a structure is complicated, and the rubber-like elastic member and the wave washer (the pressing member) has a reduced degree of freedom in shapes. 
         [0017]    As a result, it has been hard to optionally set an amount of volume change caused by the resonance frequency and the pressure, and it has been hard to achieve optimization of a diaphragm damper performance. 
       SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
       [0018]    The present invention is made by taking the problem mentioned above into consideration, and an object of the present invention is to provide a diaphragm damper which does not change the conventional metal diaphragm attaching structure, does not obstruct the space in which the fuel flows within the fuel chamber, can optionally set the amount of volume change on the basis of the resonance frequency and the pressure, and can achieve the optimization of the diaphragm damper performance. 
       Means for Solving the Problem 
       [0019]    The diaphragm damper according to the present invention is a diaphragm damper structured such that a high-pressure gas is sealed in a high-pressure chamber formed by two discoid metal diaphragms which are bonded to each other in their outer peripheral portions, wherein a rubber-like elastic member is arranged within the high-pressure chamber. 
       Effects of the Invention 
       [0020]    The present invention achieves the following effects. 
         [0021]    According to the diaphragm damper of the invention described in a first aspect, the rubber-like elastic member is arranged within the high-pressure chamber. As a result, the conventional metal diaphragm attaching structure is not changed, the space in which the fuel flows within the fuel chamber is not obstructed, it is possible to optionally set the amount of volume change on the basis of the resonance frequency and the pressure, and it is possible to achieve the optimization of the diaphragm damper performance. 
         [0022]    According to a diaphragm damper of the invention described in a second aspect, the rubber-like elastic member is constructed by a discoid sheet portion which is provided so as to come into contact with each of two discoid metal diaphragms, and a plurality of rubber projections which are arranged circumferentially between the sheet portions. As a result, it is possible to effectively damp the resonance of the metal diaphragms without obstructing deformation of the center portion in which the metal diaphragms are deformed most greatly. 
         [0023]    According to a diaphragm damper of the invention described in a third aspect, the rubber projection is integrally formed with the sheet portion and is structured such as to alternately extend from the one sheet portion toward the surface of the other sheet portion. As a result, balance of the rubber-like elastic member is good, and it is possible to effectively damp the resonance of the metal diaphragms. 
         [0024]    According to a diaphragm damper of the invention described in a fourth aspect, a leading end of the rubber projection is formed into a circular arc shape in its cross section. As a result, the following property is good in relation to the deformation of the metal diaphragms, and it is possible to effectively damp the resonance of the metal diaphragms. 
         [0025]    According to a diaphragm damper of the invention described in a fifth aspect, the rubber-like elastic member is arranged in a center portion of the high-pressure chamber so as to be concentric with the metal diaphragms. As a result, the displacement caused by the pressure of the metal diaphragm does not become uneven. Therefore, it is possible to effectively damp the resonance of the metal diaphragms. 
         [0026]    According to a diaphragm damper of the invention described in a sixth aspect, the rubber-like elastic member is in contact with both of two metal diaphragms. As a result, it is possible to more effectively damp the resonance of the metal diaphragms. 
         [0027]    According to a diaphragm damper of the invention described in a seventh aspect, the rubber-like elastic member is provided with a plurality of positioning leg portions which come into contact with an outer peripheral portion of the metal diaphragms. As a result, since it is possible to inhibit the rubber-like elastic member from moving within the high-pressure chamber, it is possible to more stably damp the resonance of the metal diaphragms. 
         [0028]    According to a diaphragm damper of the invention described in an eighth aspect, end portions of a plurality of positioning leg portions are integrally formed with a ring-shaped portion which comes into contact with an outer peripheral portion of the metal diaphragms. As a result, it is possible to more enhance the damping of the resonance in the metal diaphragms, and it is possible to more securely inhibit the rubber-like elastic member from moving within the high-pressure chamber. Therefore, it is possible to more stably damp the resonance of the metal diaphragms. 
         [0029]    According to a diaphragm damper of the invention described in a ninth aspect, the rubber-like elastic member is constructed by two discoid portions which come into contact with each of two metal diaphragms in their whole surfaces, and a connection portion which connects the two discoid portions to each other in their center portions. As a result, since the rubber-like elastic member comes into contact with the metal diaphragm in a wider range, it is possible to more securely damp the resonance of the metal diaphragms. 
         [0030]    According to a diaphragm damper of the invention described in a tenth aspect, the metal diaphragm is formed a repeated pattern of annular concave portions and annular convex portions which are formed into concentric circles. As a result, it is possible to more securely obtain a pulsation absorbing action of the diaphragm damper. 
     
    
     
       BRIEF EXPLANATION OF THE DRAWINGS 
         [0031]      FIG. 1  is a plan view of a diaphragm damper according to the present invention; 
           [0032]      FIG. 2  is a cross sectional view along a line B-B in  FIG. 1 ; 
           [0033]      FIG. 3  is a three-dimensional perspective view of a rubber-like elastic member which is used in  FIG. 2 ; 
           [0034]      FIG. 4  is a plan view of the other diaphragm damper according to the present invention; 
           [0035]      FIG. 5  is a cross sectional view along a line A-A in  FIG. 4 ; 
           [0036]      FIG. 6  is a three-dimensional perspective view of a rubber-like elastic member which is used in  FIG. 5 ; 
           [0037]      FIG. 7  is a view showing a second aspect of the diaphragm damper according to the present invention in the same manner as  FIG. 5 ; 
           [0038]      FIG. 8  is a three-dimensional perspective view of a rubber-like elastic member which is used in  FIG. 7 ; 
           [0039]      FIG. 9  is a three-dimensional perspective view of a rubber-like elastic member according to a third aspect which is used in the diaphragm damper according to the present invention; 
           [0040]      FIG. 10  is a three-dimensional perspective view of a rubber-like elastic member according to a fourth aspect which is used in the diaphragm damper according to the present invention; 
           [0041]      FIG. 11  is a three-dimensional perspective view of a rubber-like elastic member according to a fifth aspect which is used in the diaphragm damper according to the present invention; and 
           [0042]      FIG. 12  is a view showing a diaphragm damper according to the present invention which uses the rubber-like elastic member shown in  FIG. 11 , in the same manner as  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0043]    A description will be given below of the best mode for carrying out the present invention. 
         [0044]    A diaphragm damper according to the present invention is used in a high-pressure pump which pressurizes a fuel supplied from a fuel tank on the basis of a reciprocating movement of a plunger so as to pressure feed to an injector side. 
         [0045]    In this kind of high-pressure pump, a fuel chamber is formed in a fuel inlet side, and the fuel is pressurized and discharged by repeating “suction stroke” which sucks the fuel from the fuel chamber to a pressurizing chamber when a plunger moves down, “metering stroke” which returns a part of the fuel in the pressurizing chamber to the fuel chamber when the plunger moves up, and “pressurizing stroke” which pressurizes the fuel when the plunger further moves up after a suction valve is closed. 
         [0046]    The diaphragm damper according to the present invention is used for reducing pulsation which is generated in a fuel chamber of the high-pressure pump as mentioned above. 
         [0047]    Further, the diaphragm damper according to the present invention is provided with the following structures as shown in  FIGS. 1 to 3 . 
         [0048]    More specifically, a high-pressure gas is sealed into a high-pressure chamber  11  formed by two discoid metal diaphragms  1  and  1  which are bonded to each other in their outer peripheral portions  10 . 
         [0049]    Further, a rubber-like elastic member  2  is arranged within the high-pressure chamber  11 . 
         [0050]    A material of the rubber-like elastic member  2  preferably employs a rubber-like elastic material such as a nitrile rubber (NBR), a hydrogen additive nitrile rubber (HNBR), an acrylic rubber (ACM), a silicone rubber (VMQ), a fluorosilicone rubber (FVMQ), a fluorine-contained rubber (FKM), an ethylene propylene rubber (EPDM), a chloroprene rubber (CR), a chlorosulfonated polyethylene (CSM), a styrene butadiene rubber (SBR), a butyl rubber (IIR), and an urethane rubber (AU), which has a Shore hardness of Hs 50 or less. 
         [0051]    The Shore hardness Hs is set to be equal to or less because a damping function of the metal diaphragms  1  and  1  is not inhibited. 
         [0052]    According to the structure mentioned above, a space in which the fuel flows within the fuel chamber is not inhibited without changing the conventional attaching structure of the metal diaphragms  1  and  1 , and it is possible to optionally set an amount of volume change caused by a resonance frequency and a pressure, so that it is possible to optimize the diaphragm damper performance. 
         [0053]    Further, the metal diaphragms  1  and  1  are obtained by folding outer peripheral edges of two discoid members which are flat and are constructed by metal members into a curves shape and integrally bonding the outer peripheral edges to each other, and a discoid space chamber forming a high-pressure chamber  11  is formed in an inner portion of the metal diaphragms  1  and  1 . 
         [0054]    A welding means or a caulking means is appropriately selected and used for integrally bonding. 
         [0055]    The rubber-like elastic member  2  is constructed by discoid sheet portions  25  and  26  which are provided so as to respectively come into contact with two discoid metal diaphragms  1  and  1 , and a plurality of projections  251  and  261  which are circumferentially arranged between the sheet portions  25  and  26 . 
         [0056]    Further, the rubber-projections  251  and  261  are integrally formed with the sheet portions  25  and  26  as is apparent from  FIG. 2 , and are structured such as to extend from the one sheet portions  25  and  26  toward surfaces of the other sheet portions  25  and  26 . 
         [0057]    More specifically, as shown in  FIG. 3 , three rubber projections  261  are arranged on the one surface of the sheet portion  26  so as to be circumferentially uniform (at intervals of 120 degree). In the same manner, three rubber projections  261  having the same shape are arranged on the one surface of the other sheet portion  25  so as to be circumferentially uniform (at intervals of 120 degree) in the same manner. 
         [0058]    In the present embodiment, three rubber projections  251  and  261  are respectively arranged on the one surfaces of the sheet portions  25  and  26  uniformly, that is, six rubber projections are totally provided, as shown by a broken line in  FIG. 1 , however, at least two rubber projections may be respectively provided, totally four rubber projections may be provided. 
         [0059]    Further, the diaphragm damper is finished by adhering a surface where the rubber projections  251  and  261  of the sheet portions  25  and  26  are not provided, to each of the inner surfaces of the metal diaphragms  1  and  1  by an adhesive agent, thereafter assembling them in such a manner that the rubber projections  251  and  261  of the sheet portions  25  and  26  are deviated from each other at 60 degree, and integrating the outer peripheral portions  10  of two discoid metal diaphragms  1  and  1  by welding. 
         [0060]    According to the structure mentioned above, a space in which the fuel flows within the fuel chamber is not inhibited without changing the conventional attaching structure of the metal diaphragms  1  and  1 , and it is possible to optionally set an amount of volume change caused by a resonance frequency and a pressure, so that it is possible to optimize the diaphragm damper performance. 
         [0061]    Further, since a plurality of rubber projections  251  and  261  are structured such as to be uniformly arranged on the circumference which is less deformed in the outer peripheral side of the metal diaphragms  1  and  1 , it is possible to effectively damp the resonance of the metal diaphragms without inhibiting the deformation of the center portion which is most deformed in the metal diaphragms  1  and  1 . 
         [0062]    Further, since the rubber projections  251  and  261  are structured such as to extend alternately from the one sheet portions  25  and  26  toward the surfaces of the other sheet portions  25  and  26 , as shown in  FIG. 2 , the balance of the rubber-like elastic members  2  and  2  is good, and it is possible to effectively damp the resonance of the metal diaphragms  1  and  1 . 
         [0063]    Further, as shown in the drawing, leading ends of the rubber projections  251  and  261  are formed into a circular arc shape in their cross section. 
         [0064]    As a result, a good following property to the deformation of the metal diaphragms  1  and  1  can be obtained, and it is possible to effectively damp the resonance of the metal diaphragms  1  and  1 . 
         [0065]    Next, a description will be given of the other diaphragm damper according to the present invention on the basis of  FIGS. 4 to 7 . 
         [0066]    A different point from the diaphragm damper described previously exists in a point that the rubber-like elastic member  2  is provided in the center portion of the metal diaphragms  1  and  1 . 
         [0067]    The rubber-like elastic member  2  is formed into a columnar shape, and is arranged in a center portion  112  of the high-pressure chamber  11  so as to be concentric with the metal diaphragms  1  and  1 . 
         [0068]    Further, both end portions in an axial direction of the columnar rubber-like elastic member  2  are in contact with each of two metal diaphragms  1  and  1 . 
         [0069]    Further, it is effective to adhere the columnar rubber-like elastic member  2  to the metal diaphragms for holding the rubber-like elastic member  2  to the center portion  112  of the high-pressure chamber  11 . 
         [0070]    Further, the columnar rubber-like elastic member  2  may be formed into a cylindrical shape obtained by boring a center portion of the rubber-like elastic member  2 . In the case of the cylindrical shape mentioned above, the rubber-like elastic member  2  is more easily deformed. As a result, the damper function of the metal diaphragms  1  and  1  is not inhibited. 
         [0071]    Next, a description will be given of a second aspect of the diaphragm damper according to the present invention on the basis of  FIGS. 7 and 8 . 
         [0072]    A different point from the aspect described above exists in a point that the rubber-like elastic member  2  is provided with a plurality of positioning leg portions  21  and  21  which come into contact with the outer peripheral side  12  of the high-pressure chamber  11 , and a point that the metal diaphragms  1  and  1  are formed a repeated pattern of annular concave portions  13  and  13  and annular convex portions  14  and  14  which are formed into concentric circles. 
         [0073]    Three positioning leg portions  21  are formed so that three positioning leg portions are uniformly arranged from the outer peripheral surface of the columnar member  21  which is positioned at the center. 
         [0074]    Further, outer peripheral end portions of the positioning leg portions  21  and  21  are formed into a columnar projection shape. 
         [0075]    According to the structure mentioned above, since it is possible to inhibit the rubber-like elastic member  2  from moving within the high-pressure chamber  11 , it is possible to more stably damp the resonance of the metal diaphragms  1  and  1 . 
         [0076]    Further, since the metal diaphragms  1  and  1  are formed the repeated pattern of the annular concave portions  13  and  13  and the annular convex portions  14  and  14  which are formed into the concentric circles, it is possible to obtain a more secure pulsation absorbing action of the diaphragm damper. 
         [0077]    Next, a description will be given of a third aspect of the rubber-like elastic member  2  which is used in the diaphragm damper according to the present invention on the basis of  FIG. 9 . 
         [0078]    A different point from the second aspect described previously exists in a point that end portions of a plurality of positioning leg portions  21  and  21  are integrated with a ring-shaped portion  22  which comes into contact with the outer peripheral side  12  of the high-pressure chamber  11 . 
         [0079]    According to the structure mentioned above, since it is possible to further enhance the damping of the resonance of the metal diaphragms  1  and  1 , and it is possible to more securely inhibit the rubber-like elastic member  2  from moving within the high-pressure chamber  11 , it is possible to more stably damp the resonance of the metal diaphragms  1  and  1 . 
         [0080]    Next, a description will be given of a fourth aspect of the rubber-like elastic member  2  which is used in the diaphragm damper according to the present invention on the basis of  FIG. 10 . 
         [0081]    A different point from the third aspect described previously exists in a point that the rubber-like elastic member  2  is constructed only by the ring-shaped portion  22  according to the third aspect. 
         [0082]    According to the structure mentioned above, since it is possible to further hold down a capacity which the rubber-like elastic member  2  occupies within the high-pressure chamber  11 , and it is possible to inhibit the rubber-like elastic member  2  from moving within the high-pressure chamber  11 , it is possible to more stably damp the resonance of the metal diaphragms  1  and  1 . 
         [0083]    Next, a description will be given of a fifth aspect of the rubber-like elastic member  2  which is used in the diaphragm damper according to the present invention on the basis of  FIG. 11 . 
         [0084]    The rubber-like elastic member  2  is constructed by two discoid portions  23  and  23  which respectively come into contact with two metal diaphragms  1  and  1  with wide areas, and a connection portion  24  which connects two discoid portions  23  and  23  to each other in their center portions. 
         [0085]    Further, the rubber-like elastic member  2  is stored in such a manner that whole surfaces of two discoid portions  23  and  23  are respectively in contact with two metal diaphragms  1  and  1 , as shown in  FIG. 12 . 
         [0086]    According to the structure mentioned above, since the rubber-like elastic member  2  is in contact with the metal diaphragms  1  and  1  with the wider range, it is possible t more securely damp the resonance of the metal diaphragms  1  and  1 . 
         [0087]    Further, it goes without saying that the present invention is not limited to the modes for carrying out the invention mentioned above, but can employ the other various structures without deviating from the scope of the present invention. 
       INDUSTRIAL APPLICABILITY 
       [0088]    The diaphragm damper according to the present invention is useful as the diaphragm damper which is used for reducing the pulsation generated in the high-pressure pump employed in the engine.