SUSPENSION UNIT AND CONTROL THEREOF

Abstract: A suspension unit comprising a combination made up of a compression spring (99) and a shock absorber (100), the shock absorber comprising a piston (103) and a cylinder (102) mounted in parallel with the spring to provide for damping motion of the spring relative to an axis of the combination; the spring being located at or near one end on an anchorage on the cylinder and at or near the other end to the one end to a mounting point on the piston; the piston serving to define a first and a second working volumes (V1, V2) of variable size in the cylinder the volumes being on opposite sides of the piston; characterised by: a first duct (108) linking the first working volume (V1) to a control volume (110); an adjustable bump flow control means (109, 111, 111S, 111A, 111B) located between the first duct (108) and the control volume (110) providing for the regulation of flow (B) between the first duct (108) and the control volume (110); a second duct (120) linking the control volume (110) to the second volume (V2); an adjustable rebound flow control means (121, 122, 122S, 122A, 122B) located between the second duct (120) and the control volume (110) providing for the regulation of flow (R) between the second duct (120) and the control volume (110). Preferably the control means are operable manually or by way of remotely located digital or analogue controlled devices (140, 150).

Description: SUSPENSION UNIT AND CONTROL THEREOF Technical field This invention relates to a vehicle suspension unit and to its control. In particular it is concerned with a suspension unit for a ground engaging wheel of a land vehicle. Background art A conventional suspension unit is made up of a combination in parallel of a coil spring and a shock absorber connected between the vehicle and the wheel. In use the shock absorber part of the combination serves to dampen oscillation of the spring part caused by vertical motion of a wheel relative to the vehicle. By using an appropriate spring and shock absorber combination a preferred ride characteristic can be achieved. In designing suspension units for vehicles, particularly motor bikes or cars for competitive use, (such as racing and rallying) it is necessary to distinguish between the behaviour of the unit when subject to compression (Tjump') and when free to expand ('rebound'). In the past attempts to provide a practical suspension unit having independent control of bump and of rebound behaviour did not meet with success. Such a unit was generally complicated and expensive to manufacture. It did not provide for the ready modification of the bump and rebound characteristics whilst the vehicle was in motion and even with the vehicle at rest access to any built in adjustment means involved dismantling of components. Disclosure of invention According to the present invention there is provided a suspension unit comprising a combination made up of a compression spring and a shock absorber, the shock absorber comprising a piston and a cylinder mounted in parallel with the spring to provide for damping motion of the spring relative to an axis of the combination; the spring being located at or near one end on an anchorage on the cylinder and at or near the other end to the one end to a mounting point on the piston; the piston serving to define a first and a second working volumes of variable size in the cylinder the volumes being on opposite sides of the piston; characterised by: 1 a first duct (108) linking the first working volume (VI) to a control volume (110); 2 an adjustable bump flow control means (109, 111, HIS, 111 A, 11 IB) located between the first duct (108) and the control volume (110) providing for the regulation of flow (B) between the first duct (108) and the control volume (110); 3 a second duct (120) linking the control volume (110) to the second volume (V2); 4 an adjustable rebound flow control means (121, 122, 122S, 122A, 122B) located between the second duct (102) and the control volume (110) providing for the regulation of flow (R) between the second duct (120) and the control volume (110). According to a first preferred version of the present invention the suspension unit is characterised in that the flow control means (Figure 1: 109, 111, HIS, 111A, 111B; 121, 122, 122S, 122A, 122B) are operable manually. According to a second preferred version of the present invention the suspension unit is characterised in that the flow control means are operable by way of remotely located digital or analogue controlled devices (Figure 3). According to a third preferred version of the present invention or any preceding preferred versions thereof the suspension unit is characterised in that the first flow control means (Figure 1: 109, 111, 11 IS, 111 A, 11 IB) provides at least two flow paths (111, 115, 116) in parallel between the first duct (108) and the control volume (110); and the second flow control means (Figure 1: 121, 122, 122S, 122A, 122B) provides at least two flow paths (122, 126, 127) in parallel between the first duct (108) and the control volume (110). According to a fourth preferred version of the present invention or any preceding preferred version thereof the suspension unit is characterised by separate means (109, 111, 111S, 111A, 111B: 121, 122, 122S, 122A, 122B) for independent control of bump and rebound characteristics. According to a fifth preferred version of the present invention or any preceding preferred version thereof the suspension unit is characterised in that the means for adjusting the bump and rebound controllers are solenoid operated valves capable of stepped operation. According to a sixth preferred version of the present invention or any preceding preferred version thereof the suspension unit is characterised in that the anchorage (210) on the cylinder (204) comprises a first part (212) rigidly connected to the shock absorber (201) to define an annular gap (213) coaxially with the shock absorber (201); and a second part (215, 214) serving to locate the one end (231) of the spring (232); the second part (215, 214) being slidably associated with the first (212) to enclose the gap (213) so as to provided thereby a hydraulically pressurisible and variable size working volume (218); and a hydraulic pressurising unit (220) coupled to the working volume (218) to provide for the regulation of hydraulic pressure therein. According to a seventh preferred version of the present invention or any preceding preferred version thereof the suspension unit is characterised by a pressure transducer (214) communicating with the working volume (218) and coupled to a processor (247, K) adapted to provide for regulation of the ride height of the suspension unit. According to a second aspect of the present invention there is provided a wheeled motor vehicle characterised by at least one ground engagable wheel mounted on the vehicle by way of a suspension unit according to any preceding version of the present invention. Brief description of the drawings Exemplary embodiments of the invention will now be described with reference to the accompanying drawings of a suspension unit for a wheeled vehicle of which: Figure 1 is a diagrammatic sectional view of components of a first embodiment; Figure 2 is a diagrammatic sectional view of components of a second embodiment; and Figure 3 is a view of a third embodiment amounting to an elaborated version of that described in connection with Figure 2. The drawings do not purport to show the exact form or relative proportions of the components but merely their general function and their working relationship. Modes for carrying out the invention Figure 1 shows a suspension unit with manual regulation made up of a shock absorber /spring 100 and a flow /pressure control unit 101. Spring 99 is disposed around shock absorber 100. The shock absorber is made up of a tube 102 in which a piston 103 is mounted for reciprocation on a connecting rod 104. The cylinder 102 is equipped with upper end closure 105 and lower end closure 106. Upper end closure 105 is equipped with a hydraulic seal 107 to provided for the ready reciprocation of rod 104 relative to the tube 102. First volume VI beneath the piston 103 communicates by way of duct 108 and manifold 109 with interior volume 110 of control unit 101. The manifold 109 contains a spring loaded variable damping main valve 111 loaded by resilient conical washers HIS whereby the flow of hydraulic fluid in the direction of arrow B can be regulated. The setting of the valve 111 is adjustable by way of drive shaft 111 A and finger wheel 11 IB. Arrow B is one of a number of arrows identified by dots on the stem ends which show the direction of flow of hydraulic oil through the unit during a bump where the connecting rod 104 travels downwardly as viewed in Figure 1. Likewise arrows R (having a plain stem termination) show the flow of hydraulic oil through the unit during rebound when the connecting rod 104 travels upwardly as viewed in Figure 1. In addition to the main valve 111 the manifold 109 also contains a non-return valve 112 so that any overpressure in the manifold 109 as against the pressure in the volume 110 results in the valve 112 acting to vent the over pressure into the volume 110. The blow off setting of the valve 112 is established by way of drive shaft 113 and finger wheel 114. A spring loaded blow off valve 115 serves to provide for venting of overpressure arising in the volume 110 as against pressure in duct 109. An adjustable bleed valve 116 is provided to enable a permanent bleed path to be established from volume 110 into the first duct 108. The valve 116 is adjustable by way of drive shaft 117 and finger wheel 118. Second volume V2 above the piston 103 communicates by way of duct 120 and manifold 121 with interior volume 110 of control unit 101. The manifold 121 contains a spring loaded variable damping main valve 122 loaded by resilient conical washers 122S whereby the flow of hydraulic fluid in the direction of arrow R can be regulated. The setting of the valve 122 is adjustable by way of drive shaft 122A and finger wheel 122B. In addition to the main valve 122 the manifold 121 also contains a non-return valve 123 so that any overpressure in the manifold 121 as against the pressure in the volume 110 results in the valve 123 acting to vent the overpressure into the volume 110. The blow off setting of the valve 123 is established by way of drive shaft 124 and finger wheel 125. A spring loaded blow off valve 126 serves to provide for venting of overpressure arising in the volume 110 as against pressure in duct 120. An adjustable bleed valve 127 is provided to enable a permanent bleed path to be established from volume 110 into the second duct 120. The valve 127 is adjustable by way of drive shaft 128 and finger wheel 129. The interior volume 110 is separated by a diaphragm 130 from a gas pressurisible volume 131. A pressurised gas such as nitrogen is supplied to the volume 131 by way of an inlet port 132 to provide a sufficient pressure reservoir to maintain the required range of fluid pressure in the volume 110 during operation of the suspension unit. A given interior volume 110 of a control unit 101 can be used to regulate the pressure of more than one suspension unit where they are subject to similar bump and rebound cycles such as on the rear suspension of a motor bike with twin suspension arms each governed by a single suspension unit rather than a single cantilever with a single unit. The working hydraulic fluid and the containment for it provided by the shock absorber tube 102, the ducts 108, 120 and volume 110 serves as an effective heat dissipator so that even under a lengthy period of sustained operation the suspension unit is not subject to excessive temperature rise. If necessary additional heat dissipating means such as fins can be provided on the control unit 101 in the region of volume 110 and on the body of the tube 102. FIGURE 2 This shows a modified version of the manually operated suspension unit described in connection with Figure 1 to the extent that the device of Figure 2 is regulated by way of a digital processing system. The differences lie in the methods of regulating some of the flow control valves located in the manifolds. Insofar as the components of Figure 2 are similar in form and function to those in Figure 1 they are given the same reference with the addition of an apostrophe (') and are not further described in detail. Volume VI' communicates by way of duct 108' and manifold 109' with interior volume 11C of control unit 101'. The manifold 109 7 contains a spring loaded variable flow valve 111' whereby the flow of hydraulic fluid in the direction of arrow B can be regulated. The operation of the variable flow valve 111' is by way of a variable digital solenoid device 140 acting on the valve 111 by way of coupling 141. The solenoid device 140 is regulated by way of the data processor D to which it is connected by conductors 142. The manifold 109 * also contains a non-return valve 112' so that any overpressure in the manifold as against the pressure in the volume 110 results in the valve 112' acting to vent the over pressure into the volume 110. The setting of the valve 112' can be adjusted manually by way of drive shaft 117'. However this valve can also be regulated by way of a solenoid regulated by processor D. Volume V2' communicates by way of duct 120 7 and manifold 121' with interior volume 1 C of control unit 101'. The manifold 121' contains a valve 122' whereby the flow of hydraulic fluid in the direction of arrow R can be regulated. The operation of the valve 122' is by way of a variable digital solenoid device 150 acting on the valve 122' by way of coupling 151. The solenoid device 150 is regulated by way of the data processor D by way of conductors 152. The manifold 121' also contains a non-return valve 123' so that any overpressure in the manifold 121' as against the pressure in the volume lW results in the valve 123' acting to vent the over pressure into the volume 110. The setting of the valve 123'can be adjusted by way of drive shaft 127'. However this valve 123'can also be regulated by way of a solenoid operated by processor D. In addition a blow off valve 126'is provided to provided for venting of hydraulic overpressure arising in the volume 110. The interior volume HO 7 is separated by a diaphragm 130 7 from a gas pressurisible volume 131'. A pressurised gas such as nitrogen is supplied to the volume 131' by way of an inlet port 132' to provide a sufficient pressure reservoir to maintain the required range of fluid pressure in the volume 110 during operation of the suspension unit. A display panel P is located for viewing by a driver of a vehicle to which the suspension units of this embodiment are fitted. The panel P receives signals processor D and includes displays and controls to provide for the regulation of the various valves and control units and to evaluate the results of the settings chosen for those active parts of the suspension. The interpretation of the information displayed on the panel D provides for the set up of vehicle suspension to be optimised for a given usage. Figure 3 This discloses an elaborated version of the suspension unit described in connection with Figure 2. Consequently only additional items shown in Figure 3 over and above those shown in Figure 2 are described further. The differences between the Figure 3 and Figure 2 lie in three main features: the use of an annular tube layout within a shock absorber; the way the lower end of a suspension spring is mounted on the shock absorber; and the provision of a pre-loading device for the spring. RE IR D SHEET (RULE 91) Shock absorber 201 is made up of an inner tube 202 in which piston 203 slides and an outer tube 204. This serves to define an annular volume 205. First volume V below the piston 203, as in the case of the units described in connection with Figures 1 and 2, is coupled by a duct 206 feed a control unit C virtually identical to control unit 101 described in connection with Figure 2. Volume V2 located above piston 203 now includes not only the upper volume in inner tube 202 but also that in annular volume 205 the two volumes being linked by a port 207'. Duct 207 links the lower part of the annular volume 205 to the control unit C. The control unit C and the joining ducts 206, 207 function as described in relation to Figure 2 and in particular digital processor K and display panel L correspond to processor D and panel P and are similar in operation. The outer tube 204 has mounted on its outer side an anchorage 210 in two parts. The first part is an annular ring 212 brazed to the wall of tube 204. The ring 212 contains an annular slot 213 which receives an annular piston 214 on collar 215 equipped with O-rings 216, 217 to provide an annular volume 218 of variable size. Collar 215 has an upwardly projecting shoulder 230 on which is seated lower end 231 of a compression spring 232. Upper end 233 of the compression spring 232 is located by means of a plate 234 which is secured to the upper end of thrust rod 235 in the vicinity of mounting ring 236. A pipe 236' links the annular volume 218 to a pre-pressurising unit 220. The pipe 236' opens into working volume 237 of body 238 of the pre-pressurising unit 220. The size of the volume 237 can be varied by way of a piston 239 which can be driven in or out by rotating handle 240 in threaded engagement with the body 238. A pressure transducer 241 is mounted in working volume 218 and serves to sense the hydraulic pressure and if required the rate of change of hydraulic pressure in the volume 218. The output of the transducer 241 is fed to the processor 247. The output of the module 247 is fed to data processor K by lead LI. By rotating the handle 240 the volume of, and so the pressure in, the volume 237 is varied to establish the vertical position of the annular piston 214 and so the degree of spring compression and so the ride height of the vehicle. The dynamic performance of the suspension can be evaluated by the values of the transducer outputs but also by functions thereof which can be readily processed by the processor K for display on the operating panel L. The display panel L in addition to display units includes controls operable by a driver of the vehicle. In particular can be adjusted in response to information shown on the display to establish a ride height for the vehicle by suitable adjustment of the operating length of the spring 232. Further controls provide for the setting of the valves so that the desired bump and rebound characteristics of the suspension are achieved. Industrial applicability With suspension units according to the present invention incorporated in each wheel of the suspensions of a two or four wheeled road vehicle the ride of the vehicle can be closely and readily controlled typically whilst the vehicle is in use. This is particularly advantageous for a vehicle which is to be driven over a variety of surface conditions such as a rally car or any vehicle where it is necessary to set the vehicle up for one of a number of different driving surfaces. The ability to readily check the behaviour of the system while in use and where necessary introduce changes without needing to dismantle components prior to adjustment is a particular benefit. It is also a feature of the present invention that the widespread availability of digital transducers which can be located appropriately in the system means that data processing can be readily used to record and /or check the behaviour of the system under any operating conditions. This is achieved readily. The embodiments make it possible to utilise digital processors and transducers which are readily obtainable and provide for the ready handling at any feasible required speed of information acquired with the vehicle in motion. The use of a processor controlled system enables a single processor to be used for more than one suspension unit and for a display panel to provided controls which can supply adjustments to more than one such unit. Amongst other benefits such control could incorporate features preventing dangerous configurations being adopted for a set of units or at least provide a warning in an event such a configuration is selected. In addition the described embodiments readily provide for an output to be displayed giving an indication of the degeneration or failure of a unit.

Claims: CLAIMS 1 A suspension unit comprising a combination made up of a compression spring and a shock absorber, the shock absorber comprising a piston and a cylinder mounted in parallel with the spring to provide for damping motion of the spring relative to an axis of the combination; the spring being located at or near one end on an anchorage on the cylinder and at or near the other end to the one end to a mounting point on the piston; the piston serving to define a first and a second working volumes of variable size in the cylinder the volumes being on opposite sides of the piston; characterised by: 1 a first duct (108) linking the first working volume (VI) to a control volume (110); 2 an adjustable bump flow control means (109, 111, HIS, 111A, 111B) located between the first duct (108) and the control volume (110) providing for the regulation of flow (B) between the first duct (108) and the control volume (110); 3 a second duct (120) linking the control volume (110) to the second volume (V2); 4 an adjustable rebound flow control means (121, 122, 122S, 122A, 122B) located between the second duct (102) and the control volume (110) providing for the regulation of flow (R) between the second duct (120) and the control volume (110). A suspension unit as claimed in Claim 1 characterised in that the flow control means (Figure 1: 109, 111, HIS, 111A, 111B; 121, 122, 122S, 122A, 122B) are operable manually. A suspension unit as claimed in Claim 1 characterised in that the flow control means are operable by way of remotely located digital or analogue controlled devices (Figure 3). A suspension unit as claimed in any preceding claim characterised in that the first flow control means (Figure 1: 109, 111, HIS, 111A, 111B) provides at least two flow paths (111, 115, 116) in parallel between the first duct (108) and the control volume (110); and the second flow control means (Figure 1: 121, 122, 122S, 122A, 122B) provides at least two flow paths (122, 126, 127) in parallel between the first duct (108) and the control volume (110). A suspension unit as claimed in any preceding claim characterised by separate means (109, 111, HIS, 111A, 111B: 121, 122, 122S, 122A, 122B) for independent control of bump and rebound characteristics. A suspension unit as claimed in Claim 4 characterised in that the means for adjusting the bump and rebound controllers are solenoid operated valves capable of stepped operation. A suspension unit as claimed in any preceding claim characterised in that the anchorage (210) on the cylinder (204) comprises a first part (212) rigidly connected to the shock absorber (201) to define an annular gap (213) coaxially with the shock absorber (201); and a second part (215, 214) serving to locate the one end (231) of the spring (232); the second part (215, 214) being slidably associated with the first (212) to enclose the gap (213) so as to provided thereby a hydraulically pressurisible and variable size working volume (218); and a hydraulic pressurising unit (220) coupled to the working volume (218) to provide for the regulation of hydraulic pressure therein. A suspension unit as claimed in Claim 6 characterised by a pressure transducer (214) communicating with the working volume (218) and coupled to a processor (247, K) adapted to provide for regulation of the ride height of the suspension unit. A wheeled vehicle characterised by at least one ground engagable wheel mounted on the vehicle by way of a suspension unit as claimed in any preceding claim.

Inventors: NELMS CHARAN, NELMS, CHARAN
Applicants: KEYSE ROBERT JAMES, NELMS CHARAN, KEYSE, ROBERT, JAMES, NELMS, CHARAN
Application year: 1993
Main classification: B60G17
IPC codes: B60G15, F16F1, F16F9