The present specification generally relates to the field of shock absorbers used in vehicles and in particularly discloses a pressurized shock absorbing arrangement.
Shock absorbers and damping systems are used for damping of the relative movement between the wheel and the chassis of a vehicle, such as a car, a motorcycle or a bicycle. A conventional shock absorber normally comprises a working cylinder filled with a damping fluid, such as hydraulic oil or gas, and a piston arranged on a piston rod movably arranged in the cylinder. The piston is further commonly arranged to divide the cylinder into a first and second working chamber and moves in the cylinder against the resistance of the fluid, which in turn causes damping fluid to move in the damping cylinder. The shock absorber, or damper, may be arranged between the vehicle chassis and the wheel to move telescopically as the vehicle travels along such that the movement of the wheel and vehicle is thus damped by the piston moving in the cylinder against the resistance of the fluid.
Further, in order to improve the damping dynamics of a shock absorber, the damping fluid may be pressurized with a compressing pressure in order to improve the damping characteristics. However, there is a general need of improving the damping characteristics of a shock absorbers, as it can improve both driving safety, performance and comfort of a vehicle. Further, in order to implement the solutions on a wide range of vehicles there is a need for cost efficient solutions.
Accordingly, it would be desirable to provide a shock absorber having improved damping characteristics and still being cost efficient. The invention is based on the inventor's realization that by providing a shock absorber with two separate electrical continuously controlled valves, one for compression and one for rebound flow, arranged with passive valve(s) coupled in series with and downstream of the electrical continuously controlled valves and with a communication chamber coupling these valves to a pressurizing chamber, it is possible to design a cost efficient shock absorber with advantageous damping character.
The above mentioned advantages are achieved by a shock absorber, a vehicle with such a shock absorber and/or a method for controlling such a shock absorber according to the independent claims provided. Some embodiments are defined in the dependent claims.
According to a first aspect of the invention this is achieved by a shock absorber for a vehicle, comprising a damper body having an outer tube and an inner tube wherein the inner tube is arranged at least partly inside the outer tube. The shock absorber further comprises a main piston arrangement arranged in the inner tube dividing the inner tube into a first volume and second volume and configured to regulate a damping fluid flow between the first and second volumes. Further it comprises a first electrical continuously controlled valve fluidly connected to the first volume of the inner tube and configured to control the damping fluid flow during a compression stroke, a second electrical continuously controlled valve fluidly connected to the second volume of the inner tube and configured to control the damping fluid flow during a rebound stroke, a fluid reservoir for holding a pressurized gas, comprising a pressurizing piston separating the pressurized gas from the damping fluid and exerting a pressure on the damping fluid. Further, the shock absorber comprises a communication member arranged to fluidly connect the pressurizing piston with the low-pressure side of each of the first and second electrical continuously controlled valves, a first passive regulating valve fluidly arranged between the pressurizing piston and one of the first or second electrical continuously controlled valves. Finally, the fluid reservoir is co-axially arranged relative the damper body.
Hereby, a cost efficient shock absorber with advantageous damping character is achieved by using the communication member and the combination of electric continuously controlled valves with at least a passive valve. With this construction of the shock absorber, the first passive regulating valve is arranged downstream of the electrical continuously controlled valve and upstream of the pressurizing piston, allowing a control of the damping fluid pressuring to be lowered in two serial restrictions, wherein the first one is the active electric continuously controlled valve which may be adjusted by controlling the restriction based on a desired damping force at the specific moment, and thereafter further reducing the pressure before the damping fluid reaches the pressurizing piston by means of the first passive regulating valve. Further, by arranging the passive regulating valve downstream of the electric continuously controlled valve, the pressure over the electric continuously controlled valve is increased, which reduces the risk of gas bubbles occurring in the damping fluid. Further, the passive regulating valve may be used as a check valve to ensure flow of damping fluid in an undesired direction. Thereby, the passive regulating valve may be used for two functions, and thereby decreasing the number of components in the valve arrangement.
In the context of the application “fluidly coupled” should be understood as any coupling means such as a channel, pipe, hose or other fluid connection means. Moreover, in the context of the application, the wording that the pressurizing piston is “arranged, [ . . . ] inside said inner tube” comprise the different embodiments where the pressurizing piston may be arranged directly or indirectly in the inner tube, by being arranged inside one (or several) other components located inside the inner tube.
In one embodiment, the shock absorber further comprises a second passive regulating valve arranged downstream of the other one of the first or second electronic continuously controlled valve and upstream of the pressurizing piston. Hereby, each of the first and second passive regulating valves are arranged downstream of the first and second electrical continuously controlled valves, respectively, and upstream of the pressurizing piston. This allows controlling the damping fluid in both compression and rebound stroke by the means of the above mentioned two serial restrictions, i.e. first an active electric continuously controlled valve and thereafter a passive regulating valve.
The passive regulating valves may be a shim valve comprising a single shim or several shims in a stack. In other embodiments, the passive regulating valves may be a disc preloaded by a spring or a shim spring.
According to one embodiment, the damping fluid is a liquid such as damping oil, and the pressurized fluid is a gas, such as air, nitrogen, CO2.
In further one embodiment, the first electrical continuously controlled valve and the second electrical continuously controlled valve are arranged in an active valve housing being radially displaced relative the damper body.
Hereby, the total length of the shock absorber may be decreased (as opposed to when they are arranged in the axial extension of the shock absorber), which may be beneficial when mounting the shock absorber in a vehicle, since it will require less axial length.
In further one embodiment, the communication member comprises a fluid communication chamber extending along the longitudinal extension of the active valve housing, so as to fluidly connect the first electrical continuously controlled valve, the second electrical continuously controlled valve and the pressurizing piston. Hereby, the desired flow of damping fluid may be achieved in a cost- and space efficient way.
In one embodiment, the fluid communication chamber is arranged on a side of the active valve housing facing away from the main damper body. Hereby, the heavier electrical continuously controlled valves may be placed closer to the shock absorbers center axis, decreasing the stress on the construction since a shorter distance, acting as a force lever, between the main damper body and the active valve housing is enabled.
In further one embodiment, the fluid communication chamber is arranged externally of the main damper body. Hereby, assembly of the fluid communication chamber is facilitated. In one embodiment, the fluid communication chamber of is made of a die cast part or stamped sheet metal.
According to a further aspect of the inventive concept, the above-mentioned objects are achieved by an alternative shock absorber for a vehicle, comprising a damper body having an outer tube and an inner tube wherein the inner tube is arranged at least partly inside the outer tube. The shock absorber further comprises a main piston arrangement arranged in the inner tube dividing the inner tube into a first volume and second volume and configured to regulate a damping fluid flow between the first and second volumes. Moreover, the shock absorber comprises a first electrical continuously controlled valve fluidly connected to the first volume of the inner tube and configured to control the damping fluid flow during a compression stroke and further comprises a second electrical continuously controlled valve fluidly connected to the second volume of the inner tube and configured to control the damping fluid flow during a rebound stroke. Moreover, the shock absorber comprises a fluid reservoir for holding a pressurized gas, comprising a pressurizing piston separating the pressurized gas from the damping fluid and exerting a pressure on the damping fluid. The shock absorber further comprises a communication member arranged to fluidly connect the pressurizing piston with the low-pressure side of each of the first and second electrical continuously controlled valves. Finally, the shock absorber comprises a first passive regulating valve fluidly arranged between the pressurizing piston and one of the first or second electrical continuously controlled valves, and wherein the fluid reservoir is radially displaced relative the damper body.
Hereby, advantages being analogous to those described in relation to the first described shock absorber may be achieved. That is, a cost efficient shock absorber with advantageous damping character may be achieved by using the communication member and the combination of electric continuously controlled valves with at least one passive valve. Further, having the first passive regulating valve arranged downstream of the electrical continuously controlled valve and upstream of the pressurizing piston allows a control of the damping fluid pressuring to be lowered in two serial restrictions, and as already discussed it has the advantages of reducing risk of gas bubbles occurring in the damping fluid. Moreover, this embodiment also allows the total length of the shock absorber to be decreased as the fluid reservoir is radially displaced relative the active valve housing allowing the reservoir to be arranged with an axial overlap relative the extension of the damper body.
In the context of this application, the wording A is “fluidly arranged between” X and Y should be read as that the placing of object A is between object X and object Y, in the fluid path running between X and Y. Thus, object A does not need to be “fluidly arranged” as in floating.
In one embodiment, the shock absorber further comprises a second passive regulating valve arranged downstream of the other one of the first or second electronic continuously controlled valve and upstream of the pressurizing piston. Hereby, each of the first and second passive regulating valves are arranged downstream of the first and second electrical continuously controlled valves, respectively, and upstream of the pressurizing piston. This allows controlling the damping fluid in both compression and rebound stroke by the means of the above mentioned two serial restrictions, i.e. first an active electric continuously controlled valve and thereafter a passive regulating valve.
In further one embodiment, the first electrical continuously controlled valve and the second electrical continuously controlled valve are arranged in an active valve housing being radially displaced relative the damper body. Hereby, the total length of the shock absorber may be decreased (as opposed to when they are arranged in the axial extension of the shock absorber), which may be beneficial when mounting the shock absorber in a vehicle, since it will require less axial length.
In further one embodiment, the communication member is arranged as a connecting member arranged between the fluid reservoir and the active valve housing.
In further one embodiment, the communication member comprises an aperture extending along the longitudinal extension of the active valve housing, so as to fluidly connect the first electrical continuously controlled valve, the second electrical continuously controlled valve and the pressurizing piston.
Further, any compatible embodiments/features described in relation to the first described shock absorber may be implemented in the second described shock absorber.
According to a further aspect of the inventive concept, the above-mentioned objects are achieved by a vehicle comprising a shock absorber, according to any of the embodiments mentioned in this application, for damping movements between a vehicle propulsion means (such as a wheel, runner, drive belt/tracks etc.) and the vehicle's chassis.
According to a further aspect of the inventive concept, the above-mentioned objects are achieved by a method for controlling the damping flow of a shock absorber, comprising the steps of: during a compression stroke routing a compression flow of damping fluid from a first volume of an inner tube in a shock absorber to a first electrical continuously controlled valve, decreasing the compression flow pressure by means of said first electrical continuously controlled valve, routing said compression flow further to a first passive restricting valve, arranged in series with said first electrical continuously controlled valve, and finally decreasing said compression flow pressure by means of said first passive restricting valve, into a predefined low pressure level. The method further comprise the step of, during a compression stroke, routing a compression flow of damping fluid from a second volume of the inner tube in said shock absorber to a second electrical continuously controlled valve, decreasing the compression flow pressure by means of said second electrical continuously controlled valve, routing said compression flow further to a second passive restricting valve, arranged in series with said second electrical continuously controlled valve, and decreasing said compression flow pressure by means of said first passive restricting valve, into a predefined low pressure level. Further, in the method the predefined low pressure level is controlled by a pressurizing piston in a fluid reservoir.
Hereby, an efficient method may be applied to achieve an advantageous damping character by using the communication member and the combination of electric continuously controlled valves with at least a passive valve. With method, the first/second passive regulating valve is arranged downstream of the first/second electrical continuously controlled valve and upstream of the pressurizing piston, allowing a control of the damping fluid pressuring to be lowered in two serial restrictions, wherein the first one is the active electric continuously controlled valve which may be adjusted by controlling the restriction based on a desired damping force at the specific moment, and thereafter further reducing the pressure before the damping fluid reaches the pressurizing piston by means of the first passive regulating valve.
According to a further aspect of the inventive concept, the above-mentioned objects are achieved by using two electrical continuously controlled valve arrangements for controlling a damping flow in a shock absorber. The use comprising using a first electrical continuously controlled valve for decreasing a compression flow pressure from a first volume of an inner tube and thereafter decreasing said compression flow pressure further by means of a first passive restricting valve, into a predefined low pressure level. Further, the use comprises using a second electrical continuously controlled valve for decreasing a rebound flow pressure from a second volume of an inner tube, decreasing said rebound flow pressure further by means of a second passive restricting valve, into the predefined low pressure level. Further the use of said first or second electronically controlled valve together with the first or second passive restricting valve allows said predefined low pressure level to be in the range of 0.1 to 2 MPa (MN/m2), that is 100000 Pa-2000000 Pa. Hereby, as described above, a cost efficient shock absorber with advantageous damping character may be provided.
Further objectives of, features of and advantages of the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described in the following.
The invention will be understood through the following illustrative and non-limiting detailed description of preferred embodiments, with reference to the appended drawings.
All figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the invention, wherein other parts may be omitted or merely suggested. Throughout the figures the same reference signs designate the same, or essentially the same features.
The main piston arrangement 120 is connected at an end portion of a piston rod 122. The piston rod may be attached to a chassis portion of the vehicle, and so that the shock absorber may be used to absorb movements of the vehicle chassis relative a propulsion means, such as a wheel, drive belt or runner. Further, the figure illustrates an active valve housing 200 comprising a first and a second continuously controlled valve CES1, CES2, a first and a second passive regulating valve 211, 212 and a communication member 201 which fluidly connects the pressurizing piston with the low-pressure side of each of the first and second electrical continuously controlled valves. This will be further discussed in relation to close-ups in
Moreover, in
Moving on to
In
Further, as illustrated in
In
The electrical continuously controlled valves may be continuously controlled in response to an electrical signal controlling an actuator such as a solenoid or a stepping motor which controls the fluid flow through the valve.
In
Further,
Moving on to
In
Further, as illustrated in
Finally,
Further, the method as illustrated in
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. The skilled person understands that many modifications, variations and alterations are conceivable within the scope as defined in the appended claims.
Additionally, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.
In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to obtain an advantage. Any reference signs in the claims should not be construed as limiting the scope of the claims.
Number | Date | Country | Kind |
---|---|---|---|
18171990.7 | May 2018 | EP | regional |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2019/061645 | 5/7/2019 | WO | 00 |