DOUBLE-ACTING DAMPER FOR VEHICLE RIDE CONTROL

Abstract: Suspension damper (12) with variable valving within the confines of the piston (30), the variable valving being provided by first and second valve elements (48,62) which are rotatable together in one direction through a number of distinct steps to provide a wide range of jounce and rebound damping characteristics, and one of which is rotatable relative to the other in an opposite direction for maximized valve restriction producing optimized vehicle lift and dive control.

Description: This invention relates to suspension struts and shock absorbers having double-acting dampers for controlling the action of vehicle suspension springs. More particularly, this invention features a double-acting damper with new and improved variable valving providing optimized jounce and rebound control and for providing optimized and rapid control of vehicle lift and dive during vehicle braking and accelerating. In our European patent application publication no. 0186324, a selectively variable orifice damper is disclosed in which an orifice selector is rotatably positioned by an actuator to predetermined stations to vary the size of the bypass orifice to accordingly vary the damping characteristics of the unit. With this valving arrangement, there is selective and effective control of damping of the action of the vehicle suspension springs. With such variable orificing, the damper can be adjusted to suit the operator's requirements or automatically through a control program to match roadway conditions. For example, the damper may be selectively adjusted for maximum flow restriction in the piston valving to provide for a hard ride for sports car performance, for increasing flow through the piston valving for an immediate ride and normal vehicle operation and for minimum flow restriction through the valving for soft boulevard type rides. The present invention is of the general category as this damper but further incorporates new and improved staged double drum bypass valving which provides for a change in orifice size for every station or increment of valve rotation throughout a full revolution in one direction and further provides a quick shut off of the bypass valving by rotation in a reverse direction from one station to the next adjacent station. This one step reversal from any station provides for quick, highly restrictive damping and optimized control over vehicle lift and dive such as might occur when the vehicle is accelerating or decelerating. This invention further features new and improved arcuate routing of fluid through restrictions provided by the valving. An object of the present invention is to provide a new and improved damper for vehicle suspension springs having selectively variable damping characteristics provided by lost motion valving to select flow routes bypassing main piston valving and housed within the piston that features a plurality of differing flow capacity stations which do not repeat for one complete turn of the valving and which provides for lift and dive control by reversal movement of said valving to the next adjacent station from any predetermined station. To this end, a double-acting damper in accordance with the present invention is characterised by the features specified in the characterising portion of Claim 1. This invention also provides a new and improved damper for controlling the action of vehicle suspension springs which includes a double drum control valve cooperating with restricted openings in said piston to provide control flow through said piston for flow bypass in parallel with rebound and jounce control valving in said piston for a wide range of damping characteristics. This invention further provides a new and improved damper with a selected range of jounce and rebound controls and having a piston with lost motion bypass valving movable to predetermined stations to vary the orificing and flow routing at any station and to provide for quick highly restrictive orificing for lift and dive control such as might occur during vehicle acceleration or deceleration, i.e. braking. The present invention is now described, by way of example, with reference to the following detailed description and the accompanying drawings, in which:- Figure 1 is a cross-sectional view taken along lines 1-1 of Figure 3, of a portion of a suspension strut having a double-acting damper according to this invention; Figure 2 is a view taken along line 2-2 of Figure 1; Figure 3 is a cross-sectional view taken generally along line 3-3 of Figure 1 showing the bypass valving of this invention in a "home" position; Figure 4 is a cross-sectional view similar to that of Figure 3 but showing the bypass valving in another adjusted position; and Figure 5 is a cross-sectional view similar to that of Figure 4 showing the bypass valving in yet another adjusted position. Turning now in greater detail to the drawings, there is shown in Figure 1 a lower portion of a suspension strut incorporating a hydraulic double-acting damper 12 adapted to be operatively mounted between sprung and unsprung components of a vehicle. Such mounting is disclosed in U.S. Patent 4,576,258. The double-acting damper 12 has an (elongated) cylinder tube 14 having a conventional base valve 16 secured thereto in a lower end thereof which controls the passage of damper fluid between an inner (variable volume) chamber 18 of the cylinder tube 14 and a surrounding oil reservoir 20 formed between the cylinder tube and an outer support tube 22. A valved piston 30 with a connected piston rod 32 provides a piston and rod assembly that is mounted for linear stroking movement in the cylinder tube 14 during damper operations for controlling the action of the vehicle suspension springs. The piston rod 32 is an elongated cylindrical tube that extends upwardly from threaded connection at 34 with an upstanding neck 36 of the valved piston 30. From this threaded connection, the piston rod 32 extends upwardly through the upper components of the damper for operative connection with an upper mount such as disclosed in the above-referenced US patent no. 4,576,258. The hollow piston rod 32 provides a housing for an (electrically energizeable) actuator 40 that has a lower end in the form of a cylindrical wall that fits over a (reduced diameter) upper end 42 of the upstanding neck 36 of the valved piston 30 and is securely fastened thereto by pin 44. The interior of the piston rod 32 is hydraulically sealed from the fluid within the double-acting damper 12 by annular seals 45 disposed between the upstanding neck 36 of the valved piston 30 and the inner wall of the tubular piston rod as shown in Figure 1. The valved piston 30 has a cylindrical main body in the form of a thick wall shell which has upper flow passages 46 therein and which is peripherally bounded by a skirt 47 of a suitable plastics material having low friction sliding engagement with the inner wall of the cylinder tube 14. Mounted for rotational movement within the confines of the upstanding neck 36 of the piston assembly is a rotatable driver 48 having an input shaft 50 directly keyed or otherwise connected to the rotatable and downwardly extending output 52 of the actuator 40. Interior O-ring seals 54 mounted in an annular groove in the input shaft 50 provide an oil block to prevent the damper fluid from entering the interior of the piston rod 32 through the bore provided in the upstanding neck 36 for the rotatable driver 48. The rotatable driver 48 has a main body 56, cylindrical in form, with a pair of (arcuately spaced) flow openings 58 and 60 that have centrelines disposed about 135 degrees from one another as shown in Figures 3-5. The main body 56 of the rotatable driver 48 is operatively mounted within an orifice selector 62 comprising a cylindrical sleeve with fluid metering openings 64, 66 of different capacities and having their centrelines also arcuately disposed at 135 degrees from one another. The rotatable driver 48 and orifice selector 62 provide a staged double-barrel, lost motion valve assembly which are connected by a (transversely extending) drive pin 68. The drive pin 68 extends through an off-centre bore in the body of the orifice selector 62 and then into opposing slots 70 and 72 formed within the upper end of the cylindrical sleeve of the orifice selector 62 that are approximately 55 degrees in arc as shown best in Figure 2. This construction provides for the lost motion operation of the valve assembly and insures proper assembly of the rotatable driver 48 to the orifice selector 62. This drive pin 68, when in a "home" position, contacts vertical end walls 69, 69′ of the slots 70, 72 so that counterclockwise rotation of the rotatable driver 48 immediately turns the orifice selector 62 and these two parts rotate as a unit. When rotating clockwise from the "home" position, the rotatable driver 48 turns about 45 degrees before the orifice selector 62 is picked up by the drive pin 68 contacting end walls 71, 71′ of slots 70, 72 respectively. The orifice selector 62 is operatively mounted in a counterbore 85 formed in the upstanding neck 36 of the valved piston 30. O-ring seal 87 seated in an annular groove in the orifice selector 62 frictionally contacts the cylindrical wall of counter bore 85 to provide sufficient frictional drag so that the rotatable driver 48 when reversed to clockwise rotation from any predetermined selected station will not frictionally move the orifice selector 62 clockwise until the drive pin 68 moves through the lost motion arc and engages the end walls 71, 71′ defining the opposite ends of slots 70, 72. The orifice selector 62 is provided with flats or ramps 73, 74, 75, 76, 77 and 78 which provides different restrictions 79, 80, 81 and 82 between the orifice selector 62 and the counter bore 85 of the upstanding neck 36 of the valved piston 30. These restrictions have been given the values of 1, 2, 6 and 3 units, respectively, to explain the operation of this valving. The upstanding neck 36 of the valved piston 30 has arcuately disposed passages 83 and 84 which can be registered with the fluid metering openings 64, 66 in the orifice selector 62 and flow openings 58, 60 in the rotatable driver 48 as best shown in Figure 3. The passages 83, 84 are necked down to provide differing flow restrictions 86 and 88 of different capacities as will be later described. By rotating the rotatable driver 48 and orifice selector 62 as a unit to predetermined and selected positions by means of the actuator 40, various combinations of flow control orifices can be chosen to set the rebound and jounce damping characteristics of the suspension strut to meet the operator's requirements or computer signals fed into the suspension units for energizing the actuator 40 for selected degrees of counterclockwise or clockwise turning. As will be pointed out hereinafter, this preferred design has eight different flow restrictions in eight equally spaced stations in one complete rotation. Reversal in counterclockwise direction from any station to the next adjacent station provides highest restriction for lift and dive control. If one station has zero flow, this reversal would not open the bypass. As shown best in Figure 1, the valved piston 30 has a shell-like main body that houses an orifice plate assembly that includes a (cylindrical, relatively thick) fixed orifice plate 94. The fixed orifice plate 94 is peripherally secured in the main body of the valved piston 30 between an inner locator shoulder and an (inwardly coined) lower annular end 96. A lower valve spring disk pack 98 comprised of a series of flat washer-like valve disks of spring steel having decreasing diameter top to bottom is mounted adjacent to the bottom of the fixed orifice plate 94 to deflect downwardly in response to the forces of jets of hydraulic fluid thereon through passage 106 in rebound stroke (unit extension) to thereby control fluid flow through the orifice plate. An upper valve spring disk pack 100 similar to lower valve spring disk pack 98 is comprised of a series of flat washer-like valve disks is mounted adjacent to the top of the fixed orifice plate 94 which deflects in response to the force of hydraulic fluid through passages such as passage 102 on compression to provide control of fluid flow through the orifice plate on jounce strokes. The valve spring disk packs 98 and 100 are held in operative position between upper and lower limit plates 104, 107 by a centralized connector 108 having a flow opening 110 therethrough. The connector has a coined lower end 112 and a (cylindrical cup-like) upper head 114 shown in Figure 1. An elastomer O-ring seal 116 blocks the passage of peripheral fluid past the upper head 114. A helical spring 118 interposed between the upper head 114 of the connector and a washer 120 contacting the lower end of the rotatable driver 48 and orifice selector 62 and opposes the inertia of these parts during damper operation. The main body 56 of the rotatable driver 48 is hollow as shown to provide an axial passage 121 to flow opening 110 and the base valving connects flow opening 110 and inner chamber 18 to the oil reservoir 20. Figure 3 shows the bypass valving in a "home" position (arrow H) in which the flow openings 58, 60 are aligned with the fluid metering openings 64, 66 in the orifice selector 62 and the passages 83, 84 in the upstanding neck 36 of the valved piston 30. If the flow restrictions 86 and 88 in the upstanding neck 36 respectively have a value of 12 and 14 units, for example, and the fluid metering openings 64, 66 in the orifice selector 62 are, respectively, 14 and 12 units, for example, the total flow orifice would equal 24 units which flows through the flow openings 58 and 60. On rebound, this flow would be through the axial passage 121, flow opening 110, inner chamber 18 and through the base valve to oil reservoir 20. Jounce action would effect reversal of this flow. This is parallel flow that would bypass the valve restriction normally provided in the valved piston 30 and provide for a soft ride. In the event that signals from the operator or from a controller index the driver and the controller together as a unit counter clockwise 45 degrees from the Figure 3 to the Figure 4 position which is station I from "home" as indicated by arrow 1. In this position, the orifice selector 62 blocks the passages 83, 84 in the upstanding neck 36 of the valved piston 30 so that there is no flow through the bypass valving. This provides for zero bypass flow and the restriction for flow of damper fluid in jounce and rebound in the piston is provided by the main valving in the valved piston 30. This provides for a stiff sports car ride since the suspension spring checking is through the restriction in the main valving in the valved piston 30. This has been found to be desirable in many applications although other intermediate restrictions can be provided as desired. From this first station or any station, the rotatable driver 48 and orifice selector 62 can be indexed together at 45 degrees increments counterclockwise to provide a series of varying bypass opening throughout the entire 360 degrees rotary movement. Figure 5 illustrates movement of the rotatable driver 48 and orifice selector 62 together 135 degrees from "home" past a second station, not illustrated, to a third station (arrow 3). This valve staging opens the bypass valving so that jounce and rebound have a secondary and parallel flow path through the valved piston 30. On rebound, this third station flow is through radial aligned passage 83, fluid metering opening 64 and flow opening 58 into axial passage 121 and through passage 84 past the flow restrictions 86, 80 and 81 into the axial passage 121 to provide a total orifice opening of sixteen units. Restriction 81 is of no effect since it is larger than restriction 80. This provides for reduced harshness and accordingly softer ride. In the event that lift and dive control is desired, the rotatable driver 48 is rotated one station clockwise from this station or any station relative to the orifice selector 62 as provided by the lost motion drive pin 68 and slot 70,72 connection so that the bypass restriction would quickly be the highest available in the unit. This is desirable during vehicle braking for example. The front damper unit would provide resistance to prevent the car from diving and the resistance of rear damper units would be maximized to prevent the vehicle from lifting. Accordingly, this invention provides for improved lift and dive control since this condition would occur from any selected position of the valving. With this invention, the complete rotation of the valving from "home" through 360 degrees at 45 degree increments would provide for a total of eight positions and with no two positions providing for the same restriction. From any of these valve positions, a short rotation of 45 degrees of the rotatable driver 48 relative to the orifice selector 62 because of the lost motion provided by drive pin 68 in slots 70, 72 in the clockwise position would shut off the bypass flow for the dive and lift control.

Claims: 1. A double-acting damper (12) for controlling the jounce and rebound action of a suspension strut of a vehicle, the double-acting damper comprising an outer support tube (22); a cylinder tube (14) mounted within the outer support tube (22) and cooperating therewith to form an oil reservoir (20) for damper fluid; a base valve (16) operatively mounted at one end of the cylinder tube (14) for controlling the flow of damper fluid between the cylinder tube (14) and the oil reservoir (20); a piston rod (32) operatively mounted for reciprocating movement in the cylinder tube (14); a valved piston (30) secured to one end of the piston rod (32) adjacent the base valve (16); first valve means (98,100) in the valved piston (30) establishing a restricted flow through the valved piston in jounce and rebound movement thereof; and rotatable second valve means (48,62) establishing a second selectably restricted flow through the valved piston (30) in parallel with the flow through the first valve means; characterized by the second valve means having first (48) and second (62) valve elements operatively mounted for rotation within the valved piston (30) and rotatable together in one direction as a unit to a predetermined number of distinct steps to provide a different fluid flow rate through the second valve means for each of the distinct steps, and one of the first or second valve elements being rotatable relative to the other of the first or second valve elements in the opposite direction to block the flow through the second valve means. 2. A double-acting damper as claimed in claim 1, wherein the first and second valve elements (48,62) are concentrically mounted within the valved piston (30); and the second valve means further comprises a lost motion device (68,70,72) operatively connecting the first and second valve elements to provide for the relative rotation in the opposite direction. 3. A double-acting damper as claimed in claim 2, wherein the first and second valve elements (48,62) are cylindrical, and wherein the lost motion device comprises a drive pin (68) extending through the first valve element into slots (70,72) in the second valve element. 4. A double-acting damper as claimed in any one of claims 1 to 3, wherein the first and second valve elements (48,62) are rotated by a single actuator (40).

Inventors: BOCK, GUSTAVUS PEARL, FANNIN, WAYNE VINCENT, KRUCKEMEYER, WILLIAM CHARLES
Applicants: GENERAL MOTORS CORPORATION
Application year: 1988
Main classification: F16F9
IPC codes: B60G17, F16F9