Abstract:
An accumulator with a bellows dividing the accumulator into a pressure sealing chamber and a fluid flow-in chamber. A fluid inlet introduces fluid into the flow-in chamber. A bellows cap is attached to a movable end of the bellows and contains a throttling mechanism and chamber room for dampening sounds generated by pulsating waves. The throttling mechanism is positioned to oppose the fluid inlet.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an accumulator used as a pressure accumulating apparatus, a pulse pressure absorbing apparatus or the like. 
   Conventionally, an accumulator shown in  FIG. 3  has been well known and constructed as follows. 
   First, a housing  52  is provided by welding end covers  54 ,  55  to both end portions of a cylindrical shell  53 . Inside this housing  52 , an operating member  56  comprising a bellows  57  and a bellows cap  58  is accommodated. An end portion of the bellows  57  is attached to the one end cover  54  while the bellows cap  58  is mounted on the other end portion thereof. Consequently, the interior of the housing  52  is divided to a pressure sealing chamber  59  inside the bellows  57  and the bellows cap  58  aid an outside fluid flowin chamber  60  by the bellows  57  and the bellows cap  58 . 
   The end cover  54  on the one left side in this Figure is provided with a pressure supply port  61  for supplying gas into the pressure sealing chamber  59 . In this pressure support  61 , a plug member  62  for clogging this supply port  61  is fitted in. Thus, after removing this plug member  62 , gas under a predetermined pressure is supplied into the sealing chamber  59  from the supply port  61 . After supplying, the supply port  61  is clogged with the plug member  62  so as to fill the pressure sealing chamber  59  with gas under the predetermined pressure. 
   The other end cover  55  on the right side of the same Figure has a mounting portion  63  having a thread portion  64  for connecting the accumulator  51  to a fluid pipe on a system side (not shown). This mounting portion  63  contains a fluid inlet  65  for introducing fluid on the system side into the fluid flow-in chamber  60 . Therefore, the actuator  51  is connected to the system side through the mounting portion  63  so as to introduce fluid on the system side into the fluid flow-in chamber  60  through the fluid inlet  65 . 
   The accumulator  51  having the above-described structure accumulates the pressure of oil in a system and discharges the oil as a pressure accumulating apparatus. However, when the pressure of oil is accumulated or discharged, pulsating waves occur and thereby some (abnormal) sound has been generated. =p In views of the above problem, an object of the present invention is to provide an accumulator capable of damping the sound due to the pulsating wave. 
   BRIEF SUMMARY OF THE INVENTION 
   To achieve the abovedescribed object, the accumulator according to claim  1  of the present invention has such a feature that an operating member containing a bellows is disposed inside a housing so as to divide the interior of the housing to a pressure sealing chamber and a fluid flow-in chamber and the housing is provided with a fluid inlet for introducing fluid to the fluid flow-in chamber from the side of a fluid pipe, the accumulator further comprising a throttling mechanism and a chamber room for damping a sound generated by the pulsating wave, provided at a movable end portion of the operating member. 
   According to claim  2  of the present invention, there is provided the accumulator according to claim  1  wherein the operating member has a bellows cap, which is attached to the movable end portion of the bellows, and the bellows cap contains the throttling mechanism and the chamber room. 
   According to claim  3  of the present invention, theris provided the accumulator according to claim  1  or  2  wherein the throttling mechanism is provided at a position opposing the fluid inlet. 
   If fluid with pulsation flows into the accumulator of claim  1  of the present invention having the above-described structure, pulsation energy is converted to loss energy due to contracted flow and throttling by the throttling mechanism. Further, the fluid with pulsation is used as loss of dynamic pressure by provision of the chamber room. Consequently, the pulsation can be damped, so that a sound caused by the pulsating wave can be damped. 
   The bellows is made of, for example, a metallic bellows and the metallic bellows often has the bellows cap at its movable end portion. Therefore, in case where the bellows of the operating member of the present invention is a metallic bellows and the bellows cap is attached to its movable end portion, preferably, the throttling mechanism and the chamber room are provided on the bellows cap (claim  2 ). Further, preferably, the throttling mechanism is provided at a position opposing the fluid inlet (claim  3 ). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional view of an accumulator according to the embodiment of the present invention; 
       FIG. 2  is a partially enlarged sectional view showing the operating condition of the accumulator of  FIG. 1 ; and 
       FIG. 3  is a sectional view of an accumulator according to a conventional example. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The accumulator  1  of this embodiment is a metallic bellows type accumulator, which has the following structure. 
   First, a housing  2  is provided by welding an end cover  4  (called gas end cover or lid member also) to an open end portion of a bottomed cylindrical shell  3  and an operating member  5  comprising a bellows and a bellows cap (called end member also) is accommodated inside this housing  2 . An end portion (called fixed end portion also) of the bellows  6  is attached to the end cover  4  while the other end portion (called movable end portion) has a bellows cap  7 . Consequently, the interior of the housing  2  is divided to a pressure sealing chamber (called gas chamber)  8  inside the bellows  6  and the bellows cap  7  and an outside fluid flow-in chamber (called liquid chamber or fluid chamber also)  9  by the bellows  6  and the bellows cap  7 . Although such a metallic bellows as an electrodeposited bellows, formed bellows, welded bellows is used as the bellows  7 , it is permissible to use other material bellows depending on the specification or purpose of the accumulator  1 . Further, the bellows cap  7  may be formed integrally with the bellows  6 . 
   The end cover  4  which forms part of the aforementioned housing  2  is provided with a pressure supply port  10  for supplying gas into the pressure sealing chamber  8 . This pressure supply port  10  has a plug member (called gas plug also)  11  for clogging this supply port  10 . Thus, after removing this plug member  11 , gas under a predetermined pressure is supplied into the sealing chamber  8  through the supply port  10 . After supplying the supply port  10  is clogged with the plug member  11  so as to fill the sealing chamber  8  with gas under the predetermined pressure. As the kind of gas to be filled, preferably, nitrogen gas or inert gas is used. A mounting portion  12  having a thread portion  13  for connecting the accumulator  1  to a pressure pipe on a hydraulic pressure system (not shown) is provided in the center of a flat face of a wall end portion  3   a  which forms part of the housing  2 . This mounting portion  12  has a fluid inlet (called fluid introduction port or fluid passage)  14  for introducing fluid on the syssede into the fluid flow-in chamber  9 . Thus, the accumulator  1  is connected to the system side through the mounting portion  12  so as to introduce fluid on the system side into the fluid flow in chamber  9  through the fluid inlet  14 . 
   A ring-like sliding member (called vibration damping ring also)  15  is mounted on an outer periphery of the other end portion of the bellows  6  provided with the bellows cap  7  or the outer periphery of the bellows cap  7 . When the bellows cap  7  is moved while the bellow  6  is expanded or contracted, the sliding member  15  slides along an inner peripheral face of the shell  3  at the outer periphery thereof. Thus, the bellows cap  7  moves in parallel to the inner peripheral face of the shell  3  while the bellows  6  is expanded or contracted in parallel to the inner peripheral face of the shell  3  under a guide by the sliding of the sliding member  15 . Consequently, the bellows cap  7  or the bellows  6  is prevented from being caught by the inner peripheral face of the shell  3 . In the meantime, a pressure communicating portion (not shown) is provided in this sliding member  15  in order to prevent the fluid flow-in chamber  9  from being divided to a space  9   a  on the outer periphery side of the bellows  6  and a space  9   b  below the bellows cap  7  in the same Figure by the sliding member  15 . 
   A concave or stepped mounting portion  3   c  is provided in the inner face of the wall end portion  3   a  of the shell  3 , that is, in the peripheral portion of the opening of the supply port  10  of an end face portion  3   b  of the shell  3 . An outside seal  16 , an outside holder  17 , an inside seal  18  and an inside holder  19  are mounted in this mounting portion  3   c  successively from the outer periphery. 
   The outside seal  16  is provided so as to maintain the pressure of the fluid flow in chamber  9  over a predetermined value and keep the bellows  6  from being damaged. If the pressure of fluid in the fluid flowin chamber  9  or the pressure of fluid on the system side drops remarkably upon usage of the accumulator  1 , the bellows  6  is prohibited from being expanded by a difference in pressure between the inside and the outside thereof. This outside seal is formed in the following structure. 
   That is, this seal  16  is formed as a lip seal moulded of a predetermined rubber-like elastic material and as shown with an enlarged diagram of FIG.  2 . The seal  16  has an annular base portion  16   a,  which is to be pressed into the mounting portion  3   c  without being bonded thereto. An annular seal lip (called inner peripheral seal lip or first seal lip) is formed integrally on an end face on the side of the bellows cap of the base portion  16   a  such that it makes contact with the end face  7   a  of the bellows cap  7  freely detachably. An annular concave portion  16   c  is formed on the outer peripheral side of the seal lip  16   b  and an outer peripheral side seal lip (called second seal lip also)  16   d  is formed integrally on a further outer side of this concave portion  16   c  such that it is always in a firm contact with the inner face of the mounting portion  3   c.    
   As shown in the same Figure, the seal lip  16   b  is formed as an outward directed seal lip whose diameter is expanded outward in the diameter direction from a proximal portion to a distal portion thereof. When this seal lip  16   b  makes contact with the end face  7   a  of the bellows cap  7 , it is pressed by a pressure within the fluid flow-in chamber  9 , which is a resistant pressure of sealed fluid, against the end face  7   a  so that it makes a firm contact therewith. Therefore, an outer peripheral face of this seal lip  16  serves as a pressure receiving face. Two annular rows of sealing protrusions  16   e,    16   f  are provided coaxially at a front end portion of the seal lip  16   b  and these seal protrusions  16   e,    16   f  make contact with the end face  7   a  of the bellows cap  7 . 
   Consequently, even if a foreign substance in fluid is caught between any one of the sealing protrusions  16   e,    16   f  and the end face  7   a  of the bellows cap  7  so that the sealing performance between the sealing protrusion  16   e  or  16   f  and the end face  7   a  is lost, the other sealing protrusion  16   e  or  16   f  keeps a firm contact with the end face  7   a  throughout the entire circumference so as to maintain the sealing performance. Because such double structure of the sealing protrusions  16   e,    16   f  is provided, the sealing performance of the entire seal lip  16   b  is improved. The number of the rows formed for the sealing protrusions  16   e,    16   f  is not restricted to two rows, but may be three or more. When the bellows cap  7  is, after moved, stopped by the end face  3   b  of the shell  3  or other stoppers (not shown), the sealing protrusions  16   e,    16   f  make contact with the end face  7   a  of the bellows cap  7 . Thus, the seal lip  16   b  does not bear the operation or burden as a stopper which stops the bellows cap  7  moving toward it. 
   The outside holder  17  disposed on the inner peripheral side of the outside seal  16  is formed in an annular shape of rigid material such as metal or resin, and is comprised of a flat portion  17   a,  which is flat and annular or double-ring like, and a cylindrical rising portion  17   b,  which is formed integrally with this flat portion  17   a  such that it rises from the outer peripheral end portion of the flat portion  17   a  toward the bellows cap  7 , its section being L-shaped or substantially L-shaped. 
   The inner peripheral end portion of the flat portion  17   a  is engaged with an annular stepped engaging portion  19   a  provided in the outer peripheral face of the inside holder  19 . Therefore, when the inside holder  19  is inserted into the fluid inlet  14  and fixed therein, the outside holder  17  gets fixed to the shell  3 . The rising portion  17   b  is disposed just on the inner peripheral side of the outside seal  16  and a front end portion thereof is expanded in a trumpet-like or tapered form, so that the rising portion  17   b  holds the outside seal  16  from being removed from the mounting portion  3   c.  This rising portion  17   b  has also the function of backing up the seal lip  16   b  of the outside seal  16 . When the bellows cap  7  comes into contact with the end face  3   b  of the shell  3  or other stoppers and is stopped after the bellows cap  7  moves toward it so that a gap is generated between the rising portion  17   b  and the end face  7   a  of the bellows-cap  7 . Thus, the rising portion  17   b  is always prohibited from being in contact with the bellows cap  7 . 
   Like the outside seal  16 , the inside seal  18 , which is disposed on the inner peripheral side of the holder  17  and held by this holder  17 , is provided so as to maintain the pressure of the fluid flow-in chamber  9  over a predetermined value and keep the bellows  6  from being damaged, so that if the pressure of fluid in the fluid flow-in chamber  9  or the pressure of fluid on the system side drops remarkably upon usage of the accumulator  1 , the bellows  6  is prohibited from being expanded by a difference in pressure between the inside and the outside thereof. This inside seal is formed in a following structure. 
   That is, this seal  18  is formed as a lip seal moulded of a predetermined rubber-like elastic material and as shown in the enlarged diagram of FIG.  2 . The seal  18  has an annular base portion  18   a,  which is to be pressed into the inner peripheral side of the outside holder  17  without being bonded thereto. An annular seal lip (called inner peripheral seal lip or first seal lip)  18   b  is formed integrally on an end face on the side of the bellows cap  7  of the base portion  18   a  such that it makes contact with the end face  7   a  of the bellows cap  7  freely detachably. An annular concave portion  18   c  is formed on the outer peripheral side of the seal lip  18   b  and an outer peripheral side seal lip (called second seal lip also)  18   d  is formed integrally on a further outer side of this concave portion  18   c  such that it is always in a firm contact with the inner face of the outside holder  17 . 
   As shown in the same Figure, the seal lip  18   b  is formed as an outward directed seal lip whose diameter is expanded outward in the diameter direction from a proximal portion to a distal portion thereof. When this seal lip  18   b  makes contact with the end face  7   a  of the bellows cap  7 , it is pressed by a pressure within the fluid flow-in chamber  9 , which is a resistant pressure of sealed fluid, against the end face  7   a  so that it makes a firm contact therewith. Therefore, an outer peripheral face of this seal lip  18   b  serves as a pressure receiving face. Two annular rows of sealing protrusions  18   e,    18   f  are provided coaxially at a front end portion of the seal lip  18   b  and these seal protrusions  18   e,    18   f  make contact with the end face  7   a  of the bellows cap  7 . 
   Consequently, even if a foreign substance in fluid is caught between any one of the sealing protrusions  18   e,    18   f  and the end face  7   a  of the bellows cap  7  so that sealing performance between the sealing protrusion  18   e  or  18   f  and the end face  7   a  is lost, the other sealing protrusion  18   e  or  18   f  keeps a firm contact with the end face  7   a  throughout the entire circumference so as to maintain the sealing performance. Because such double structure of the sealing protrusions  18   e,    18   f  is provided, the sealing performance of the entire seal lip  18   b  is improved. The number of the rows formed for the sealing protrusions  18   e,    18   f  is not restricted to two rows, but may be three or more. When the bellows cap  7  is, after moved, stopped by the end face  3   b  of the shell  3  or other stoppers (not shown) the sealing protrusions  18   e,    18   f  make contact with the end face  7   a  of the bellows cap  7 . Thus, the seal lip  18   b  does not bear the operation or burden as a stopper which stops the bellows cap  7  moving toward it. 
   The inside holder  19  disposed on the inner peripheral side of the outside holder  17  and the inside seal  18  is formed in a cylindrical or pipe-like form of such rigid material as metal or resin, and is comprised of an insertion portion  19   b  having a relatively small diameter and to be inserted into the fluid inlet  14  and a rising portion  19   c  formed integrally with this insertion portion  19   b  and having a relatively large diameter. The aforementioned annular stepped engaging portion  19   a  is provided on the border between this insertion portion  19   b  and the rising portion  19   c.    
   Although the insertion portion  19   b  is fixed to the shell  3  after it is pressed into the fluid inlet  14 , it is permissible to expand the front end portion (bottom portion in the same Figure) of the insertion portion  19   b  in a trumpet-like or tapered form after the insertion portion  18   b  is inserted into the fluid inlet  14  so that it is fixed to the shell  3 . In this case, part of the inner face of the fluid inlet  14  is provided with a trumpet-like or tapered engaging portion  14   a  preliminarily. 
   As shown in  FIG. 2 , where the bellows cap  7  comes into contact with the end face  3   b  of the shell  3  or other stoppers, a gap is generated between the bellows cap  7  and the end face  7   a  of the bellows cap  7 . Thus, the rising portion  19   c  is always prohibited from being in contact with the bellows cap  7 . 
   Further, the accumulator  1  of this embodiment contains an abnormal sound preventing mechanism having the following structure. 
   As shown in FIG.  1  and  FIG. 2 , the bellows cap  7  mounted on the movable end portion of the bellows  6 , which is the operating member  5 , is provided with a through hole-like throttling mechanism  20  damping a sound generated by pulsating waves and having a relatively small diameter. Further, a cup-like  3  chamber forming member  21  is mounted on the side of the sealing chamber  8  of the bellows cap  7  and on the inner side of the bellows  6  by engaging, bonding or welding. This chamber forming member  21  forms a chamber room  22  having a predetermined capacity for damping a sound generated by the pulsating waves. The through hole-like throttling mechanism  20  is provided in the center of the flat face of the bellows cap  7  such that it opposes the fluid inlet  14 . The chamber room  22  communicates with the fluid-fauw chamber  9  through the throttling mechanism  20 . The bellows cap has a stepped engaging portion  7   b  for positioning the chamber forming member  21  in the center of the flat face. 
   The accumulator  1  having the aforementioned structure accumulates and discharges the pressure of oil in the system as a pressure accumulating apparatus and the following operation and effect are exerted with the aforementioned structure. 
   That is, there is a fear that the pulsating wave is generated when the pressure of oil is accumulated or discharged, thereby generating a sound (abnormal sound). If fluid with the pulsating wave flows into the fluid flow-in chamber  9  through the fluid inlet  14  in the accumulator  1  having the above-described structure, pulsating wave energy is converted to loss energy due to contracted flow and throttling by the through hole-like throttling mechanism  20  and used as loss of dynamic pressure by the chamber room  22 . Thus, the pulsating wave can be damped and consequently, a sound generated by the pulsating wave can be damped. The abnormal sound preventing mechanism comprised of the throttling mechanism  20  and the chamber room  22  acts in a range from zero in system pressure to a gas sealing pressure. 
   The present invention exerts the following effects. 
   In the accumulator  1  of claim  1  having the above-described structure, if fluid with pulsating of the system side flows into the accumulator, the pulsating energy is converted to loss energy due to contracted flow and throttling by the throttling mechanism provided on the movable end portion of the operating member including the bellows and used as loss of dynamic pressure by the chamber room. Consequently, the pulsating can be damped so that a sound due to the pulsating wave can be damped. Therefore, an accumulator having an excellent silencing performance can be provided. 
   Further, in the accumulator of claim  2  of the present invention, if fluid with pulsating of the system side flows into the accumulator, the pulsating energy is converted to loss energy due to contracted flow and throttling by the throttling mechanism provided on the bellows cap mounted on the end portion of the bellows and used as loss of dynamic pressure by the chamber room. Consequently, the pulsating can be damped so that a sound due to the pulsating wave can be damped. Therefore, an accumulator having an excellent silencing performance can be provided. Additionally, in the accumulator according to claim  3  of the present invention, because the throttling mechanism is provided at a position opposing the fluid inlet, the throttling mechanism is likely to be actuated to fluid flowing through the fluid inlet. Even if the movable end of the operating member or the bellows cap approaches the fluid inlet, the operation for damping the pulsation can be exerted. 
   DESCRIPTION OF REFERENCE NUMERALS 
   
       
         1 : accumulator 
         2 : housing 
         3 : shell 
         4 : end cover 
         5 : operating member 
         6 : bellows 
         7 : bellows cap 
         8 : pressure sealing chamber 
         9 : fluid flow-in chamber 
         10 : pressure supplying port 
         11 : plug member 
         12 : mounting portion 
         13 : thread portion 
         14 : flow inlet 
         15 : sliding member 
         16 ,  18 : seal 
         17 ,  19 : holder 
         20 : throttling mechanism 
         21 : chamber forming member 
         22 : chamber room