Abstract:
A pressure regulator is provided for adjusting a pressure in a hydraulic flow, which pressure can be at least partially regulated using a solenoid. The solenoid can adjust a position of a driver that comprises a solenoid armature, a solenoid armature rod, and a delimiting part. The solenoid armature can be arranged around a solenoid armature rod and can be axially displaceable inside a solenoid chamber in a housing. The solenoid armature rod can have one or more holes that fluidly interconnect a first chamber to a solenoid chamber of the regulator. The delimiting part can be arranged around the solenoid armature rod adjacent to the housing and be configured such that clearances between the delimiting part, the solenoid armature rod, and the housing enable a certain radial movement between the driver and the housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage application under 35 U.S.C. §371 of PCT Application No. PCT/EP2010/058809 designating the United States, filed Jun. 22, 2010. The PCT Application was published in English as WO 2010/149652 A1 on Dec. 29, 2010 and claims the benefit of the earlier filing date of Swedish Patent Application No. 0900870-7, filed Jun. 25, 2009. The contents of Swedish Patent Application No. 0900870-7 and International Application No. PCT/EP2010/058809 including the publication WO 2010/149652 A1 are incorporated herein by reference in their entirety. 
     BACKGROUND 
     1. Field of the Inventions 
     The inventions relate to an electrically controlled pressure regulator, which comprises an actuator in the form of a solenoid primarily intended to determine the pressure in a damping medium flow between the damping chambers of a shock absorber. 
     2. Description of the Related Art 
     A known design within the field of the inventions is described by patent SE531108 of the Applicant, in which the closing actuating force of a pilot stage in a shock absorber valve is determined by the force from an electrically controlled solenoid. 
     In this patent application, a valve/pressure regulator is described in the form of a pilot-controlled two-stage valve, intended to control a damping medium flow between the two damping chambers of a hydraulic shock absorber. The shock absorber valve comprises a valve housing having at least one main valve with a movable valve part in the form of a main cone disposed between a main valve spring arrangement and a seat, as well as a pilot valve comprising a pilot slide. The main cone delimits a pilot chamber in the valve housing, in which the valve main spring and the pilot slide are disposed. The characteristics of the shock absorber valve are primarily controlled by the pressure build-up in the pilot chamber that is adjusted by the position of the pilot slide in the pilot chamber. The position is determined by the force balance between the spring force of a pilot spring and the counter actuating force from an electrically controlled solenoid, but also by the feedback pressure opening force created by the pressure in the pilot chamber. Energization of the solenoid adjusts the position of a driver or a solenoid armature having a solenoid armature rod disposed inside a solenoid chamber in the solenoid. The solenoid chamber is pressurized by virtue of the fact that a longitudinal and a transverse hole run in the solenoid armature rod and connect the pilot chamber to the solenoid chamber. As a result of different diameters of the upper and lower part of the pilot slide, a certain damping of the movement of the pilot slide is created. 
     The pressurization of the solenoid chamber causes damping medium to flow through the solenoid that thus can become more sensitive to dirt. Precise tolerances between the solenoid armature rod and the valve housing are therefore required to enable dirt insensitivity to be attained. Precise tolerances can lead to high production costs and a certain undesirable friction. 
     SUMMARY 
     Certain embodiments reduce the friction and the production costs in a pressure regulator regulated by a solenoid. 
     Certain embodiments also create a pressure regulator having a robust construction that is relatively insensitive to tolerances. 
     Certain embodiments further create a pressure regulator having minimized sensitivity to fouling. 
     In certain embodiments, the pressure regulator adjusts the pressure in a hydraulic flow between a first and a second chamber. The pressure is partially or wholly regulated by an energization of a solenoid that adjusts a position of a driver. The driver comprises a solenoid armature arranged around or integrated with a solenoid armature rod and is axially displaceable inside a solenoid chamber in a housing. The solenoid chamber is pressurized with a solenoid chamber pressure by virtue of the fact that one or more holes in the solenoid armature rod connect the first chamber to the solenoid chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an embodiment of a pressure regulator connected to a shock absorber. 
         FIG. 2  shows a detailed view of those parts of the pressure regulator embodiment that are movable in relation to one another and between which a hydraulic flow can pass. 
         FIG. 3   a  shows an embodiment of the solenoid-controlled driver of the pressure regulator. 
         FIG. 3   b  shows another embodiment of the solenoid-controlled driver of the pressure regulator. 
         FIG. 3   c  shows a detailed view of yet another embodiment of the solenoid-controlled driver of the pressure regulator. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an embodiment of a shock absorber valve connected to a hydraulic shock absorber SA for a vehicle in which the valve controls the pressure in a damping medium flow Q in , Q out  into, out of or between the two damping chambers C 1 , C 2  of the shock absorber. The flow between the two damping chambers occurs through displacement of a main piston DP that is disposed in the damper body and delimits the two damping chambers C 1 , C 2 . The flow of the damping medium in the valve is primarily determined by the speed of the main piston DP and by the piston and piston rod diameters thereof. The valve is a one-way valve, in which the flow Q in  goes into the valve and the flow Q out  goes out of the valve, i.e. the damping medium flow takes the same path and flows in a direction irrespective of the direction in which the main piston DP moves in the damper body. The pressure is adjusted via an ECU-controlled continuous electric signal that controls the current supply to the valve according to working principles described in EP 0 942 195. 
     The embodiment of the shock absorber valve in  FIG. 1  includes a valve housing  2  comprising at least one main valve having an axially movable main cone  9 . The main cone  9  is biased by a main valve spring  10  against a main seat  11 . The main cone  9  is also arranged such that it delimits a pilot chamber V p  in the valve housing  2 . The main valve spring  10 , and a pilot valve cone  4  and a pilot valve seat  3  are disposed in the pilot chamber V p . 
     The main flow Q in  creates a pressure on the main cone  9  that contributes to a regulator force R that opens the valve, i.e. forces the main cone  9  from the main seat  11 . Once the valve has opened, the main flow goes via the regulatable flow opening that arises between the main seat  11  and the main cone  9  in the direction Q in  to Q out , or in through a hole  9   a  in the main cone  9  into the pilot chamber V p . The valve is preferably a two-stage, pilot-controlled valve, which means that the force that opens the main valve is dependent on the pilot pressure P p  which arises in the pilot chamber V p . 
     The characteristics of the shock absorber valve are thus mainly controlled by a pressure regulator that adjusts a hydraulic flow between a first chamber V p1  and a second chamber V p2 . The flow between the chambers is regulated partially or wholly by energization of a solenoid that adjusts an axial position of a driver in relation to a housing. The driver per se is connected to and adjusts the position of an axially movable cone in relation to a seat. 
     In this case, the pressure regulator adjusts the pressure in a pilot chamber V p , i.e. the flow between the first and the second pilot valve chamber V p1 , V p2 , by adjusting the position of a pilot valve cone  4  in relation to a pilot valve seat  3 , see  FIG. 2 . 
     The mutual relationship of the pilot valve cone  4  and the pilot valve seat  3  creates a regulatable flow opening arranged to restrict a pilot damping medium flow q. The regulatable flow opening, which has a flow diameter defined by the measure D 1 , creates a restriction of the flow q that produces a pressure difference between the pressures P p1 , P p2  that arises upstream and downstream respectively of the restriction. This pressure difference can be close to 10 bar. The size of the flow opening and the position of the pilot valve cone  4  in the pilot chamber V p  are determined by a force balance on the pilot valve cone  4 . The force balance is primarily created by the sum of an actuating force F and the force Fs from a spring arrangement against the action of the regulator force R created by the main flow Q in . The spring arrangement comprises, for example, a first and/or a second spring  5 ,  6 , which can be configured as helical springs and/or washer-shaped shim springs. In  FIGS. 1 and 2 , the first spring  5  is a helical spring and the second spring  6  is a shim spring. 
     The actuating force F is created by an electrically controlled solenoid  12  arranged to regulate the position of the pilot valve cone  4  in relation to the pilot valve seat  3  via a driver  13  that is axially movable in the valve housing  2  and comprises a solenoid armature rod  13   a  and a solenoid armature body  13   b.    
     In  FIGS. 3   a  and  3   b  is shown an enlarged view of embodiments of the driver  13  and its parts. The solenoid armature rod  13   a  has a diameter d 1  that is smaller than the diameter d 2  of the solenoid armature body  13   b . When the solenoid armature rod  13   a  is axially displaced, it slides against an upper and a lower plain bearing  14   a ,  14   b  disposed in the valve housing  2 . Between the plain bearings  14   a ,  14   b  and the rod  13   a  there is, for production engineering reasons (i.e., from a manufacturing point of view), a first clearance cl 1  of a predetermined size. The size of this first clearance cl 1  contributes, inter alia, to a reduced friction and helps to possibly reduce the tolerance requirements of the solenoid armature rod  13   a  and the valve housing  2 . 
     In  FIG. 3   a , a hole  13   c  extends, parallel with the axis of symmetry of the rod  13   a , through the whole of the solenoid armature rod  13   a . Through this hole  13   c , damping medium can pass to a solenoid chamber V s  that is disposed in the valve housing  2  within the interior of the solenoid  12 . The damping medium flows through the hole  13   c , so that the solenoid chamber V s  is pressurized with a solenoid chamber pressure P s . Due to a large diameter of the hole  13   c , the restriction of the damping medium flow between the pilot chamber V p  and the solenoid chamber V s  is sufficiently small that the solenoid chamber pressure P s  is substantially as great as the pilot pressure P r . 
     When a shim spring is used as the second spring  6 , as shown in  FIGS. 1 ,  2  and  3   a , a hole  16  of diameter d h  can be disposed in the center thereof that allows damping medium to flow through the axial hole  13   c  in the solenoid armature rod  13   a  with little or no restriction. A small restriction can result in a certain damping of the movements of the driver  13 . 
     The size of the actuating force F that acts counter to the total force Fs of the spring arrangement is limited for, for example, flow limitation and spatial reasons, i.e. the solenoid design. That is to say, the difference between the forces Fs from the spring arrangement and the actuating force F limits how high the pilot pressure P p  can be. In one embodiment, in order to increase the maximum level of the pilot pressure, the area, referred to as the total pressure feedback area A, that is acted upon by the pilot pressure is reduced. The total feedback area A is determined by the difference between a first and a second area; A 1 -A 2 . A 1  is the effective first area of diameter D 1  that is acted upon by the pilot pressure P p , in this case determined by the seat diameter D 1  of the regulatable flow opening which restricts the pilot damping medium flow q. A 2  is the effective second area, determined by the diameter d 1  of the solenoid rod  13   a , that is acted upon by the solenoid chamber pressure P s . Around other parts disposed in the solenoid chamber, substantially the same pressure P s  prevails, which means that they do not contribute to any change in static force. Thus A=pi*(D 1   2 −d 1   2 )/4. 
     The pressure feedback area A does not have any lower size limit since the diameters for the respective effective area can be freely chosen. Nor is there theoretically any upper limit for the height to which the pilot pressure P p  can be adjusted. Preferably, only the seat diameter D 1  defined by the inner seat edge  3   b  is used to determine the pressure feedback area. To be able to choose a large number of pressure ranges merely by the choice of one dimension of a component has great significance for the production costs for certain embodiments. In certain embodiments, the pressure feedback is possible by virtue of the hydraulic connection of the pilot chamber V p  and the solenoid chamber V s  via the hole  13   c  in the solenoid armature rod  13   a . In some embodiments, in order to increase this pressure feedback or differential feedback, as it may also be called, a groove  20  can be disposed in the upper plain bearing  14   a . The groove offers greater possibilities for the hydraulic medium to flow from the pilot to the solenoid chamber without restriction. The groove  20  is shown with a dashed line in  FIG. 3   a.    
     In some embodiments, a delimiting part in the form of a washer  18  is arranged around the solenoid armature rod  13   a  adjacent to the valve housing  2 . The washer  18  has a suitably small third clearance cl 3  between its inner diameter d 18i  and the solenoid armature rod  13   a , and a second, larger clearance cl 2  between its outer diameter d 18y  and the housing  2 . The second clearance cl 2  corresponds to or is larger than the first clearance cl 1  between the solenoid armature rod  13   a  and the valve housing  2 , preferably up to three times larger, but this relationship can vary. As a result of this relationship between the clearances, a certain radial movement is permitted between the driver and the housing  2 . Moreover, a play  21  is also permitted between the solenoid armature rod  13   a  and the pilot valve cone  4 , which results in no transfer of lateral forces from the solenoid to the valve housing  2 . 
     In certain embodiments, the third clearance cl 3  is as small as possible from a production engineering aspect and preferably has a size of between a maximum clearance of 6/1000 and a minimum clearance of 1/1000 of the outer diameter d 1  of the solenoid rod, i.e. a fit between the outer diameter d 1  of the solenoid rod and the housing  2  that is between H 7 /g 6  and optimally H 6 /g 5 , maximally H 6 /f 5 . As a result of having a minimal third clearance cl 3  between the inner diameter of the washer  18  and the solenoid armature rod  13   a , very little damping medium flows through the hole  13   c  in the solenoid armature rod  13   a , via the solenoid chamber V s  and to the downstream pilot chamber V p2 . A small clearance cl 3  helps attain low leakage through the inner, dirt-sensitive parts of the solenoid. 
     The washer  18  bears against the valve housing  12  adjacent to the lower plain bearing  14   b . The contact surface between the valve housing  2  and the washer  18  is kept shut and seals, regardless of the operating situation. This by virtue of the fact that the oil works with a sticking force, at the same time as the washer  18  is acted upon by the solenoid chamber pressure Ps, which compresses the washer  18  against the valve housing  2 . The pressing force is created by a pressure difference over the washer  18  that arises by virtue of the fact that the second pilot pressure P p2 , downstream of the restriction between the pilot valve seat  3  and the pilot valve cone  4 , is significantly less than the solenoid chamber pressure P s , which is substantially equal to the first pilot pressure P p1 . 
     In  FIG. 3   b  is shown an alternative embodiment in which the axially extending hole  13   c  through the solenoid armature rod  13   a  is no longer continuous, but is terminated such that a second part of the solenoid armature rod having the upper area A 2  and diameter d 1  is solid. The hole  13   c  thus extends only through a first part of the solenoid armature rod  13   a . In order to lead damping medium into the solenoid chamber V s  and still create a pressure-balanced solenoid armature  13   b , the axial hole  13   c  is terminated in radial holes  13   d  extending between the hole  13   c  in the solenoid armature rod and the solenoid chamber V s . In this embodiment, the solenoid armature rod  13   a  operates as an extra damping piston in the limited space in the form of an upper solenoid chamber Vs u  disposed above the solenoid armature rod  13   a . The damping is created by virtue of the fact that the damping medium in the upper solenoid chamber Vs u  that is dispelled by the solenoid armature rod  13   a , is forced to flow through the first gap cl 1  and out into the solenoid chamber V s . 
     In addition, in this  FIG. 3   b , the spring arrangement that creates the spring force F s  is replaced by a single helical spring  5 . The spring arrangement that is shown in  FIGS. 1-3   a  can also be used in this embodiment. The hole  16  in the second shim spring  6  then creates an extra damping in series with the damping movement of the solenoid armature rod in the space Vs u . 
     In another embodiment, a further pressing pressure can be created by the arrangement of a spring  19 , see  FIG. 3   c , between the washer  18  and the solenoid armature body  13   b . The spring  19  works with low force, which can be somewhat greater than the own weight of the washer  18 , and with low spring constant, in order not to otherwise affect the valve function. The spring  19  may be either configured as a helical spring  19 —straight or conically or as a shim spring/cup spring with bent-up arms. Another alternative embodiment is that the washer  18  itself both seals and is springy and can then have a shim-like character, for instance, in the form of a thin washer with bent-up arms. 
     The inventions are not limited to the embodiments that are shown above by way of example, but instead can be modified within the scope of the following patent claims and the inventive concept. For example, the solenoid-controlled pressure regulator can, of course, be used in controlling other than pilot pressure in a shock absorber valve and can also be used in other types of valves, such as various types of one-way or non-return valves biased by springs.