Referring now to the drawings, there is illustrated in
The upper mount assembly 11 also includes a dust cover 20. The dust cover 20 functions as a protective guard against debris (e.g., stones) from the road that may cause damage to any underlying components of the actuator 10. A piston assembly 22 is also coupled to the upper mount assembly 11. The piston assembly 22 includes a piston rod 24, a piston rod head 26, a piston 28, and a piston spring 29. The piston rod 24 is coupled to the piston rod head 26 (e.g., threaded) or may be formed integral as one component. The piston 28 includes a check valve assembly 31 coupled to a bottom surface of the piston 28. Preferably, the piston 28 is a free floating piston which is slideable over the piston rod head 26 as described in co-pending application U.S. Ser. No. 10/892,484 filed Jul. 16th, 2004, which is incorporated herein by reference.
The actuator 10 further includes a lower mount assembly 30. The lower mount assembly 30 includes a fastening member 32 coupled to a first mass 33 of the vehicle such as a sway bar (sprung member). The lower mount assembly 30 further includes a lower housing portion 34. An inner tubular member 36 spaced radially outward from the piston assembly 22 extends into the lower housing portion 34 and is coupled to the lower housing portion 34 therein. An outer tubular member 35 spaced radially outward from the inner tubular member 36 is sealing engaged to the lower housing portion 34. A low pressure accumulator 37 is formed between the outer tubular member 35 and the inner tubular member 36. The accumulator 37 is partially filled with hydraulic fluid and partially filled with a gas, such as nitrogen. A high pressure chamber 42 is formed between the inner tubular member 36 and the piston assembly 22.
A cap assembly 40 is seated on top of the outer tubular member 35 and the inner tubular member 36. The cap assembly 40 includes a centered aperture 43 for receiving the piston rod 24 axially therethrough for attachment to the upper mount assembly 11. The piston spring 29 extends axially around the piston rod 24. The ends of the piston spring 29 are bound by an abutment portion 44 of the upper cap assembly 40 and an abutment portion 46 of the piston 28.
The cap assembly 40 is disposed above the high pressure chamber 42 and is in fluid communication with the high pressure chamber 42. The cap assembly 40 includes a fluid conduit 46 that coupled to a transfer tube 48 disposed within the accumulator 37. Pressurized hydraulic fluid exits from the top of the high pressure chamber 42 via the first conduit 46 and is provided to the transfer tube 48. The transfer tube 48 extends between the upper cap assembly 40 and the lower housing assembly 34 within the accumulator 37 for allowing fluid flow between the upper cap assembly 40 and a solenoid valve 56 disposed in the lower housing assembly 34.
Referring to
The lower housing assembly 34 further includes a first passageway 54 that fluidically connects the transfer tube 48 to the solenoid valve 56 disposed within the lower housing assembly 34. A second passageway 55 fluidically connects the accumulator 37 to the solenoid valve 56. The solenoid valve 56 includes electrical leads 53 (shown in
A portion of the flow deflector 50 is positioned directly above the portal 57 for preventing hydraulic fluid from jetting above the surface of the hydraulic fluid stored in the accumulator 37. Preventing the jetted hydraulic fluid from breaching the surface of the hydraulic fluid within the accumulator 37 substantially reduces the formation of gas bubbles within the hydraulic fluid.
A controller (not shown) provides control signals to energize the solenoid valve 56 between the open or closed position depending on the vehicle operating conditions. The controller senses a plurality of operating conditions, including but not limited to speed, lateral acceleration, and steering wheel angle. A semi-active roll control algorithm will process the information and, based on the sensed inputs, will produce a control command indicating whether to close or open the solenoid valve 56 for maintaining a rigid or non-rigid suspension system.
As the force exerted on the lower mount assembly 30 is removed, the piston spring 29 uncompresses and forces the piston 28 back to an extended position (or centered position). As the piston transitions from a compressed position to the extended position, the positioning of the piston in cooperation with a pressure differential causes hydraulic fluid to be drawn from the accumulator 37 back into the high pressure chamber 42. Hydraulic fluid is drawn from the accumulator 37 to the high pressure high pressure chamber 42 by a second portal 59 (shown in
The flow deflector 50 includes a substantially arc-shaped underbody surface 58. The flow deflector 50 is positioned over the portal 57 of the second passageway 55. Hydraulic fluid forced into the accumulator 37 under high pressure from the portal 57 jets into the accumulator 37 in a vertical upward direction. The jetted hydraulic fluid is gradually deflected in a substantially horizontal direction by the arc-shaped underbody surface 58 of the flow deflector 50. Thus, the deflected hydraulic fluid flows in a horizontal circular direction and is prevented from flowing upward and breaching the surface of the existing hydraulic fluid within the accumulator 37. Preventing the jetted hydraulic fluid from breaking the surface of the hydraulic fluid minimizes the gas bubbles within the hydraulic fluid in the accumulator 37.
The flow diverter 66, if made of an elastomeric material, also has the advantage of functioning like a check valve for preventing the return of hydraulic fluid from the accumulator 37 to the high pressure chamber 42 via the flow diverter 66. In the unlikelihood of a small amount of gas bubbles formed in the hydraulic fluid of the accumulator 37, gas bubbles could return to the high pressure chamber 42 via the perspective flow diverter. That is, gas bubbles formed in the liquid float upward; however, because of the viscosity of the hydraulic fluid (e.g., oil), the gas bubbles may not disperse above the surface of the hydraulic fluid in a timely manner that would be warranted. Rather, the gas bubbles may be slow to float to the surface and may remain suspended in the hydraulic fluid. Under such conditions, a respective flow diverter having an opening at a respective height above the bottom surface of the accumulator 37 may be susceptible to allowing gas bubbles suspended within the hydraulic fluid to flow therein to the high pressure chamber 42. Unlike portal 57 disposed on the bottom surface 86 of the accumulator 37, as shown in
A reed valve 96 is coupled to the main body 91 and extends laterally along the wall section 92. The reed valve 96 is made of an elastomeric material, such as rubber, which allows the reed valve 96 to move the directions as shown by the direction indicator 97 when respective forces are exerted on the reed valve 96. When no forces are acting on the reed valve 96, a portion of the reed valve 96 abuts the apex 95. Alternatively, the reed valve 96 may be positioned so that the reed valve 96 is in close proximity to the apex 95.
A first chamber portion 98 is cooperatively formed by the first sloping surface 93 and reed valve 96. The first chamber portion 98 is disposed above the portal 57 and is in fluid communication with the portal 57. The first chamber 92 widens as it extends along the first sloped surface 93 from the apex 95 to an opposing end portion of the first chamber portion 98 that is in fluid communication with the portal 57.
A second chamber portion 99 is cooperatively formed by the second sloping surface 94 and reed valve 96. The second chamber portion 99 widens as it extends from its apex 95 to an opposing end of the second chamber portion 99 that is in fluid communication with the accumulator 37.
A narrowed passageway 100 is formed between the apex 95 and the opposing section of the reed valve 96 which allows fluid flow from the first chamber portion 98 to the second chamber portion 99. When hydraulic fluid is forced from high pressure chamber 42 (not shown) to the accumulator 37, pressurized hydraulic fluid is forced into the first chamber portion 98 via portal 57. As fluid flow increases into the first chamber portion 98, pressure builds into the tapered portion of the first chamber portion 98 to force the reed valve 96 in the direction A as indicated by the direction indicator 97. As fluid flows through the narrowed passageway 100, fluid flow increases as pressure decreases. Hydraulic fluid flows into the second chamber portion 99. The second chamber portion 99 widens as fluid flows from the apex 95, and thereafter, into the accumulator 37. As fluid flows into the widening second chamber portion 99, fluid flow decreases and pressure increases thereby reducing abrupt pressure changes and minimizing the jetting fluid and turbulence.
The hydraulic fluid entering the accumulator 37 from the second chamber portion 99 is forced in a substantially horizontal direction which prevents hydraulic fluid from jetting above the surface of the hydraulic fluid thereby minimizing the formation of gas bubbles within the hydraulic fluid of the accumulator 37.
When hydraulic fluid returns to the high pressure chamber 42 from the accumulator 37, fluid flow is prevented from re-entering the flow diverter 90. As fluid attempts to re-enter the flow diverter 90 from the accumulator 37, a vacuum is created from the high pressure chamber 42. The vacuum attempts to draw fluid from the accumulator 37 into the second chamber portion 99. In response to the vacuum created by the reverse fluid flow, the reed valve 96 is forced in the direction B as indicated by the direction indicator 97. The portion of the reed valve 96 collapses against the second sloped surface 93 and the apex 95 thereby stopping any additional hydraulic fluid from passing through flow diverter 90 and to the high pressure chamber 42. Any gas bubbles suspended within the hydraulic fluid which may have formed are prevented from flowing to the high pressure chamber 42 through the flow diverter 90.
It should be noted gas bubbles suspended in the high pressure chamber 42 exit the high pressure chamber 42 via first conduit 46 coupled to the top of the high pressure chamber 42. The gas bubbles travel through the transfer tube 48 and into the accumulator via the first portal 57 where the hydraulic fluid and gas bubbles disposed therein are redirected in the substantially horizontal direction by a respective flow diverter. These gas bubbles circulate within the accumulator 37 and gradually rise to the top surface as the hydraulic fluid flow rate decreases within the accumulator 37 thereby purging the gas bubbles within the high pressure chamber 42.
A fence portion 108 is disposed around the second portal 59 and extends vertically upward into the accumulator 37. The fence portion 108 includes a mesh-type material having mesh-like openings 109 that allows for fluid flow therethrough. As fluid exits from the accumulator 37 through the second portal 59, hydraulic fluid is drawn through fence portion 108. The fence portion 108 screens gas bubbles suspended within the hydraulic fluid of the accumulator 37 as the hydraulic fluid passes through the fence portion 108 thereby minimizing gas bubbles from flowing through the second portal 59 and to the high pressure chamber 42.
The fence portion 108 may be extended to only a predetermined height for allowing flow over in the event the hydraulic fluid becomes highly viscous. Under certain conditions (e.g., cold weather), the hydraulic fluid within the accumulator 37 may have high viscosity. Depending upon the size of the mesh openings of the fence portion 108, hydraulic fluid may be restricted from flowing through the mesh openings of the fence portion 108 or may flow at a very slow rate. By limiting the height of the fence portion 108, the fence portion 108 may function as a weir for allowing hydraulic fluid to flow over a top unrestricted opening 110 of the fence portion 108 should the hydraulic fluid be too viscous to flow through the mesh-type openings 109 of the fence portion 108.
Referring to
Referring again to
In alternative embodiments, a respective fence portion may be designed utilizing difference diameters, heights, and geometrical configurations based on the size, location, and shape of a respective second portal. In addition, the fence portion can be utilized with the various embodiments of flow diverters as discussed above. Moreover, the centrally disposed second portal 59′ may be utilized without a respective fence since gas bubbles have a tendency to float upward and away from the lower central portion of the accumulator.
In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.