Abstract:
A pressure control valve includes a main valve unit provided with a main valve element and a valve housing body having a main valve seat capable of seating the main valve element and having a pilot chamber for slidably housing the main valve element. A pilot valve unit is provided with a pilot valve element and a pilot valve seat member has a pilot valve seat capable of seating the pilot valve element and separating the pilot valve element from the pilot valve seat and opening when a pressure in the pilot chamber exceeds a predetermined pressure. The pressure control valve is configured with recessed (concaved) parts that form hydraulic fluid channels between the pilot valve seat member and the pilot valve element when the pilot valve unit is in an open-valve-state at three or more locations so as to be separated by equal angles. Each recess has the same shape.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application relates to and claims priority from JPCT/JP2013/052541 filed Feb. 5, 2013, the entire contents of which are incorporated herein by reference. 
     
    
     FIGURE SELECTED FOR PUBLICATION 
       [0002]    
       FIG. 2 
     
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to a pressure control valve applied in the fluid pressure circuit used in an industrial vehicle and a control valve system including a pressure control valve as a constituent element. 
         [0005]    2. Description of the Related Art 
         [0006]    Conventionally, referring now to  FIG. 5  and as set forth below, a balance piston type valve is known as a pressure control valve and is used in a fluid pressure circuit used for industrial vehicles. This type of pressure control valve V is installed between an input port a 1   c  receiving an operation fluid and a tank port a 1   d  continuously connected to a tank for storing operation fluid and valve V comprises a main valve element a 6  and a valve seat a 7   a  in which the main valve element a 6  can seat and also a main valve unit a 4  formed by utilizing a valve storage body a 7  having a pilot chamber a 7   b  in which the main valve element a 6  is slidably stored, the pilot valve element a 8 , and a pilot valve unit a 5  formed by utilizing a pilot valve seat member a 9  having a pilot valve seat a 9   a  in which the pilot valve element a 8  can seat and fixedly installed in the main valve unit a 4 . Both the main valve element a 6  and the pilot valve element a 8  are biased by a biasing means a 101 , a 102  (such as a spring) to seat respectively in the main valve seat a 7   a  and the pilot valve seat a 9   a . Then, when both the main valve unit a 4  and the pilot valve unit a 5  are in the closed valve state, fluid pressure inside the input port a 1   c  is operative to the pilot valve element a 8  through the inside of the pilot chamber a 7   a.    
         [0007]    Then, when the inside pressure of the input port a 1   c  becomes higher than the predetermined pressure, fluid pressure operative to the pilot valve element a 8  is stronger than the biasing force by the biasing means a 102  and the pilot valve element a 8  separates from the pilot valve seat a 9   a  and the pilot valve unit a 5  will be in the open valve state. Then, as the inside of pilot chamber a 7   b  continuously connects to the tank port aid, the differential pressure between the inside of input port a 1   c  and the inside of pilot chamber a 7   b  is generated and the force due to the differential pressure is stronger than the biasing force by the biasing means a 101  so that the main valve element a 6  leaves from the main valve seat a 7   a  and the main valve unit a 4  will also be in the open valve state. 
         [0008]    Accordingly, while the pilot valve unit a 5  is in the open valve state and the main valve unit a 4  is in the closed valve state, operation fluid flows through the gap between the pilot valve seat a 9   a  and the pilot valve element a 8  of the pilot valve seat member a 9 , but unfortunately the central axis of the pilot valve seat a 9   a  and the central axis of the pilot valve element a 8  may not be always coaxial and also the back-and-forth direction of the pilot valve element a 8  may not be the same as the extending direction of the central axis of the pilot valve element a 5 . Therefore, in the case of these situations the pilot valve element a 8  is eccentric relative to the pilot valve seat a 9   a  and operation fluid flows through the gap, the problem takes place, wherein as a result the pilot valve element a 8  can vibrate due to the fluid pressure of fluid and collides with the pilot valve seat member a 9  to make abnormal noise, causing premature wear, leakage and other defects. 
         [0009]    One construction in an effort to solve such problems is disclosed in which a guide to keep slidably the pilot valve element is installed to make the back-and-forth direction of the pilot valve element as the same as the extending direction of the central axis of the pilot valve element (e.g., Patent Document 1, the entire contents of which are incorporated by reference). 
         [0010]    However, unfortunately according to the constitution disclosed in Patent Document 1, since the guide member must be additionally installed and modified, the number of parts and assembly processes increase so that an increase of the production cost can be raised as another problem. 
       PRIOR ART DOCUMENTS 
     Patent Document 1: JP Patent Published H11-311349 
     ASPECTS AND SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
       [0011]    The purpose of the present invention, focusing on the above points, is to prevent or suppress an occurrence of the defect making an abnormal noise without increasing the number of parts and assembly processes, which takes place when the pilot valve unit is in the open valve state and the pilot valve element vibrates because of receiving fluid pressure and collides with the pilot valve seat member. 
       Means for Solving the Problem 
       [0012]    A pressure control valve of the present invention has the following construction. Specifically, the pressure control valve of the present invention is the pressure control valve including: a main valve element and a main valve seat in which the main valve element can seat and also a main valve unit including a valve storage body having a pilot chamber in which the main valve element is slidably stored; a pilot valve seat member including a pilot valve element and a pilot valve seat in which the pilot valve element can seat; and a pilot valve unit that will open as the pilot valve element separates from the pilot valve seat when the pressure of the inside of the pilot chamber becomes higher than the predetermined pressure of the spring urging force, wherein a concave part forming the flow passage for the operation fluid in between the pilot valve element when said pilot valve unit is in the open valve state is separated from each other with the same angle and formed at more than three places in the pilot valve seat member, and also each concave part has the identical shape. 
         [0013]    Further, the control valve of the present invention includes at least a casing in which an input port receiving the operation fluid and an open tank port continuously connecting to an external storage tank (not shown), and the control valve installed between the input port and the tank port inside the casing. 
         [0014]    Accordingly, during a use the present invention pilot valve element receives the fluid pressure from the operation fluid flowing through each flow passage but a perpendicular component, relative to the back-and-forth direction of the composition of fluid pressures from the operation fluid flowing through each flow passage, is erased because each adjacent flow passage separates (or estranges) with the same relative angle and each concave part has the identical shape. As a result, a member guides the back-and-forth direction of the pilot valve element installed so that the defect making an abnormal noises is prevented or suppressed without increasing the number of parts and assembly processes, which takes place when the pilot valve element takes the open valve position, and also prevents the pilot valve element vibrating because of receiving the fluid pressure that collides with the pilot valve seat member. 
       Effects of the Invention 
       [0015]    According to the present invention and construction thereof, the occurrence of the defect making an abnormal noise is prevented or suppressed without increasing the number of parts and assembly processes, which takes place when the pilot valve unit is open, and it is now recognized that the pilot valve element vibrates because of receiving fluid pressure and in response collides with the pilot valve seat member. 
         [0016]    According to the present invention, a pressure control valve includes a main valve unit provided with a main valve element and a valve housing body having a main valve seat capable of seating the main valve element and having a pilot chamber for slidably housing the main valve element. A pilot valve unit is provided with a pilot valve element and a pilot valve seat member has a pilot valve seat capable of seating the pilot valve element and separating the pilot valve element from the pilot valve seat and opening when a pressure in the pilot chamber exceeds a predetermined pressure. The pressure control valve is configured with recessed parts that form hydraulic fluid channels between the pilot valve seat member and the pilot valve element when the pilot valve unit is in an open state at three or more locations so as to be separated by equal angles. Each of the recessed parts has the same shape. 
         [0017]    The above and other aspects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a schematic diagram illustrating a control valve of the present invention. 
           [0019]      FIG. 2  is a schematic diagram illustrating a pressure control valve of the invention. 
           [0020]      FIG. 3A  is a front view illustrating a control valve seat member of the invention. 
           [0021]      FIG. 3B  is a cross-sectional side view along line  3 B- 3 B in  FIG. 3A . 
           [0022]      FIG. 4  is an explanatory drawing illustrating the behavior of the pressure control valve of the present invention in a movement position. 
           [0023]      FIG. 5  is a schematic diagram illustrating a conventional pressure control. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Reference will now be made in detail to embodiments of the invention. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps. The drawings are in simplified form and are not to precise scale. The word ‘couple’ and similar terms do not necessarily denote direct and immediate connections, but also include connections through intermediate elements or devices. For purposes of convenience and clarity only, directional (up/down, etc.) or motional (forward/back, etc.) terms may be used with respect to the drawings. These and similar directional terms should not be construed to limit the scope in any manner. It will also be understood that other embodiments may be utilized without departing from the scope of the present invention, and that the detailed description is not to be taken in a limiting sense, and that elements may be differently positioned, or otherwise noted as in the appended claims without requirements of the written description being required thereto. 
         [0025]    Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments of the present invention; however, the order of description should not be construed to imply that these operations are order dependent. 
         [0026]    Hereafter, the inventor sets forth the first Embodiment of the present invention referring  FIG. 1-FIG .  4 . 
         [0027]    Referring to  FIG. 1 , the control valve C of the present invention is used in a fluid pressure system applied for the industrial vehicles and includes at least a casing  1 , a flow dividing valve  2  mountable to the casing  1 , and a pressure control valve  3  operably mountable to casing  1 . A pressured oil input port  1   a  operates as an input port receiving an operation fluid (fluid not shown), a steering passage  1   b  is provided to operably discharge the operation fluid to the fluid pressure system, not shown in FIG., to control the steering of a vehicle (not shown) during a use. A loading and unloading passage  1   c  is provided to discharge the operation fluid to the fluid pressure system (complete system not shown), to control a loading and unloading equipment of a vehicle. A low pressure passage  1   d  is positioned as the tank port continuously connecting to the tank (not shown) to store the operation fluid in an operable manner in casing  1 . Flow dividing valve  2  is installed inside a flow dividing valve storage hole  1   e  continuously connected to pressured oil input port  1   a , steering passage  1   b  and loading and unloading passage  1   c  is operative to inlet a part of the operation fluid input from pressured oil input port  1   a  via the continuous passage installed in the inside thereof to the steering passage  1   b  and also to inlet the remaining operation fluid input from the pressured oil input port  1   a  by operably changing the opening level corresponding to an inside pressure of the pressured oil input port  1   a  to the loading and unloading passage  1   c.    
         [0028]    Pressure control valve  3 , installed between the loading and unloading passage  1   c  and the low pressure passage  1   d , includes a main valve unit  4  and a pilot valve unit  5 , as shown. 
         [0029]    Here, as will be understood from study of the provided disclosure, the operation fluid input from pressured oil input port  1   a  to control valve C, as set forth above, is divided into steering passage  1   b  and loading and unloading passage  1   c  via flow dividing valve  2  during a use thereof. Accordingly, when, during a use, the fluid pressure of the operation fluid divided into the loading and unloading passage  1   c  becomes higher than the permitted predetermined pressure; firstly the pilot valve unit  5  of the pressure control valve  3  will open and then the main valve unit  4  will open. At that time, upon such opening, the operation fluid flows out from the loading and unloading passage  1   c  to the low pressure passage  1   d.    
         [0030]    Specifically, the pressure control valve  3  functions to control the pressure inside the loading and unloading passage  1   c  so as to not be higher than the predetermined pressure (e.g., a release pressure). 
         [0031]    Hereafter, the inventor sets forth the specific constitution of the pressure control valve  3 . 
         [0032]    Referring additionally to  FIG. 2 , pressure control valve  3  includes a main valve element  6  and a main valve seat  7   a  in which main valve element  6  can seat during a use, and also a main valve unit a 4  formed by utilizing a valve storage body  7  having a pilot chamber  7   b  in which the main valve element  6  is slidably stored, a pilot valve element  8 , and a pilot valve unit  5  formed by utilizing a pilot valve seat member  9  having a pilot valve seat  9   a  in which the pilot valve element  8  can seat fixedly installed in the main valve unit  4  during a use. Further, as set forth above, the pressure control valve  3  is installed between the loading and unloading passage  1  and the low pressure passage  1   d , by which during a use when the pilot valve unit  5  and the main valve unit  4  are open, the loading and unloading passage  1   c  and the low pressure passage  1   d  are continuously connected and in other cases, in-between of the loading and unloading passage  1   c  and the low pressure passage  1   d  is blocked. 
         [0033]    Main valve unit  4  is formed by utilizing the main valve element  6  and the valve storage body  7  having the main valve seat  7   a  in which the main valve element  6  can seat. The main valve element  6  that is a bottomed cylindrical member having internal space  6   a  open in the opposite direction to the direction toward the main valve seat  7   a  comprises an orifice continuously connecting the internal space  6   a  and the loading and unloading passage  1   c . On the other hand, the valve storage body  7  comprises the first sleeve  71  arranged in the side of the loading and unloading passage  1   c  and the second sleeve  72  which stores a part of first sleeve  71  in the one end and of which the other end is mounted to casing  1 . First sleeve  71  is the cylindrical member having the operation fluid input port  71   a  continuously connecting to the loading and unloading passage  1   c  at the end of the side toward loading and unloading passage c and also having a first operation fluid discharge port  71   b  continuously connecting to the low pressure passage  1   d  in the side surface and is formed as pilot chamber  7   b  inside which the main valve element  6  is slidable. Main valve seat  7   a  is formed at the upstream side edge of pilot chamber  7   b . Second sleeve  72  is connected to the opposite side edge of the operation fluid input port  71   a  of the first sleeve  71  with a screw (not shown, or other connection mechanism) and stores the pilot valve element  8  of the pilot valve unit  5  in the inside thereof. Second sleeve  72  includes the second operation fluid discharge port  72   a  continuously connecting the internal space and low pressure passage  1   d . During a use, main valve unit  4  selects either a closed-valve-state in which main valve element  6  seats in main valve seat  7   a  or the open-valve-state in which main valve element  6  separates (estranges) from main valve seat  7   a . Further specifically, a spring  101  is operative as a biasing mechanism or means and in use biases main valve element  6  toward main valve seat  7   a  between the bottom of the internal space  6   a  of main valve element  6  and the bottom of pilot valve seat member  9 ; and when a differential pressure between the inside of the pilot chamber  7   b  and the loading and unloading passage  1   c  takes place because the pilot valve unit  5  is in the open-valve-state, the operative force due to the differential pressure for main valve element  6  is stronger than the biasing force of spring  101  and main valve unit  4  will advance and move to the open-valve-state. 
         [0034]    As set forth above and referring to  FIG. 2 , the pilot valve unit  5  is formed by utilizing pilot valve element  8  that is movable back-and-forth in the inside of second sleeve  72  of valve storage body  7  of main valve unit  4 ; and, pilot valve seat member  9  having pilot valve seat  9   a  in the inside thereof in which pilot valve element  8  can seat, and fixedly installed in between first sleeve  71  of valve storage body  7  of main valve unit  4  and second sleeve  72 . 
         [0035]    Pilot valve element  8  includes valve element main body  81  having approximately conical shape in which the diameter thereof is getting smaller in the direction toward loading and unloading passage c (as shown) and guide unit  82  extends to the opposite direction away from loading and unloading passage  1   c  and slides and moves inside second sleeve  72 . 
         [0036]    On the other hand, referring additionally to  FIG. 3 , pilot valve seat member  9  includes a flange part  91  installed between first sleeve  71  and second sleeve  72 , a mounting part  92  extending from flange part  91  to loading and unloading passage  1   a  and installed inside sleeve  71 , and pilot valve seat  9   a  at the end of the opposite direction to the direction toward the loading and unloading passage  1   c . During a use, pilot valve unit  5  selects either the closed-valve-state in which pilot valve element  8  seats in main valve seat  9   a  or the open-valve-state in which pilot valve element  8  estranges from main valve seat  7   a.    
         [0037]    Further specifically, a spring  102  is operable as a biasing mechanism or means and is operable to bias pilot valve element  8  toward pilot valve seat  9   a  and is installed between a rear anchor of guide  82  and second sleeve  72  (as noted in  FIG. 2 ), and when the fluid pressure induced from loading and unloading passage  1   c  into the inside of pilot chamber  7   b  via an orifice  6   b  of the main valve element is higher than the predetermined pressure (from the spring force of spring  102 ), the operative force due to the fluid pressure for pilot valve element  8  is stronger than the biasing force of the spring  102  and pilot valve unit  5  will be in the open-valve-state. 
         [0038]    As noted directly in  FIG. 3 , a plurality of concave parts  9   x  are formed in the flow passage along seat  9   a  for the operation fluid in between pilot valve element  8 , when pilot valve element  8  is in the open-valve-state (is separated) and formed at three and more places in pilot valve seat member  9  each with the same angle. All concave parts  9   x  have the identical shape and the bottomed ditch drilled toward outside of pilot valve seat  9   a . Further, each concave part  9   x  has an approximately arc shape in the rear view thereof. In addition, the shape of each concave part  9   x  can be set as any shape that is operative for the function of concave parts  9   x  as discussed herein. 
         [0039]    Then, during further operation when the fluid pressure inside the loading and unloading passage  1   c  is higher than the predetermine pressure, firstly, the force due to the fluid pressure operative to the pilot valve element  8  becomes stronger than the biasing force operative to the pilot valve element  8  (by spring  102 ); and pilot valve element  8  leaves from pilot valve seat  9   a  and pilot valve unit  5  will be in the open-valve-state referring to  FIG. 4 . At this time, a gap S is generated between pilot valve element  8  and pilot valve seat member  9 . The width of gap S where concave parts  9   x  is installed is larger than other parts and consequently the operation fluid flows mainly inside concave part  9   x . Then, the force due to the fluid pressure of the operation fluid flowing inside the concave part  9   x  and operative to the pilot valve element  8  has a component in the leaving direction from pilot valve seat  9   a  along with the center of axis of pilot valve element  8  and in the direction toward the center of axis of pilot valve element  8 . However, the concave parts  9   x  are estranged (separated) from each other with the same angle and all of them have the identical shape so that all components of the force due to the fluid pressure of the operation fluid and operative to pilot valve element  8  in the direction toward the center of axis have the same severity and the forces are therefore compensated and erased each other. Accordingly, when pilot valve element  8  is in the open-valve-state, the force due to flow of the operation fluid has only the component in the aligned leaving direction from pilot valve seat  9   a  along with the center of axis of pilot valve element  8 . Then, the operation fluid inside pilot chamber  7   b  is discharged to low pressure passage  1   d  via second operation fluid discharge port  72   a  and the differential pressure between loading and unloading passage  1   d  and pilot chamber  7   b  so that the force due to the differential pressure can be stronger than the biasing force of spring  101  operative to main valve element  6  leaves (separates) from main valve seat  7   a  and then main valve unit  4  will be in the open-valve-state. 
         [0040]    Specifically, according to the present invention, it will be understood that concave parts  9   x  having identical shape are estranged (separated) from each other with the same angle, in the same shape, and are installed at the equally spaced three places in pilot valve seat member  9  (as shown in  FIG. 3A ), and when pilot valve element  8  is in the open-valve-state, the operation fluid flows between concave parts  9   x  and pilot valve element  8  so that the force due to flow of the operation fluid, as set forth above, has only the force component in the leaving (separation) direction from pilot valve seat  9   a  along the center of axis of pilot valve element  8 . Accordingly, the present invention prevents an occurrence of a defect making an abnormal noise occurring when a conventional pilot valve element  8  in the open-valve-state and vibration because of receiving fluid vector pressures colliding with the pilot valve seat member  9  are prevented without increasing the number of parts and assembly processes. 
         [0041]    Further, according to the present Embodiment, concave parts  9   x  are installed at the three places (in the preferred embodiment) so that a minimum number of processes can bring the realization of the constitution of pilot valve seat member  9 , by which the above effects can be obtained, and also pilot valve element  8  can be pressed along the same axis mechanically and most stably by the operation fluid flowing inside the concave part  9   x.    
         [0042]    Further, it will be understood that the present invention is not limited to the embodiment discussed above. For example, the concave part portions (shown as  9   x ) installed in the pilot valve seat member is not limited to the three places (as shown) and may be installed at more than four places so that the effective impact of the fluid forces also provide co-axial affects and produce no vibration or noise. Also, the present concepts may not only be applied as the constituent element of the control valve used in the industrial vehicles, but also the pressure control valve relative to the present invention may be applied alone as a relief valve opened when the high pressure port fluid pressure in e.g., the fluid pressure circuit is higher than the predetermined fluid pressure. 
         [0043]    Further the present invention can be modified within the scope and spirit of the present disclosure in a variety of aspects unless otherwise departing from the spirit of the present invention. 
       INDUSTRIAL APPLICABILITY 
       [0044]    The present invention provides industrial applicability since the proposed invention minimizes the abnormal noises and vibration that take place because the present inventive system addresses the vibration caused by the receiving fluid pressure collides with the pilot valve seat, and minimizes the impact thereof without increasing the number of parts and assembly processes. 
         [0045]    Having described at least one of the preferred embodiments of the present invention with reference to the accompanying drawings, it will be apparent to those skills that the invention is not limited to those precise embodiments, and that various modifications and variations can be made in the presently disclosed system without departing from the scope or spirit of the invention. Thus, it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents. 
       EXPLANATION OF REFERENCES 
       [0000]    
       
         C Control valve 
           1  Casing 
           3  Pressure control valve 
           4  Main valve unit 
           5  Pilot valve unit 
           6  Main valve element 
           7  Valve storage body 
           8  Pilot valve element 
           9  Pilot valve seat member 
           9   x  Concave parts