DESC:FIELD OF INVENTION
[0001] The present subject matter described herein generally relates to a suspension system for a vehicle including two-wheeled vehicles and particularly, but not exclusively relates to a damping adjuster assembly of said suspension system.
BACKGROUND OF INVENTION
[0002] Two-wheeled vehicles are typically provided with suspension systems including a spring and a damper unit, which serves to absorb energy released during different riding conditions, and especially during bumpy ride conditions. The spring typically absorbs energy generated due to road disturbances. Further, the absorbed energy is released during spring extension, which in turn is further absorbed by the damper unit, thereby aiding in avoiding unsettled motion of the vehicle. Thus, the suspension systems typically aid in minimizing the vibrations experienced by the rider when the vehicle is ridden over uneven surfaces.
[0003] However, conventional suspension systems provide fixed damping characteristics and do not permit damping adjustment. As a result, vehicle handling and comfort performance delivered to the rider for riding across different terrains such as good roads and bad roads and different usage modes of the vehicle such as solo and duals is limited.
[0004] Therefore, in order to provide enhanced customer comfort and vehicle handling comfort, under different conditions of riding, it is desirable to provide a suspension system including a damper assembly which is adapted to provide variable compression and rebound damping.

BRIEF DESCRIPTION OF DRAWINGS
[0005] The detailed description of the present subject matter is described with reference to the accompanying figures. Same numbers are used throughout the drawings to reference like features and components.
[0006] FIG.1 illustrates a cross sectional view of a suspension system in accordance with an embodiment of the present invention.
[0007] FIG.1a illustrates a cross sectional view of a rod guide of said suspension system in accordance with an embodiment of the present invention.
[0008] FIG.1b illustrates a cross sectional view of the suspension system in accordance with a second embodiment of the present invention.
[0009] FIG.2 illustrates a cross sectional view of a damping adjuster assembly in accordance with an embodiment of the present invention.
[00010] FIG.3 illustrates an exploded view depicting parts of a compression damping adjuster unit in accordance with an embodiment of the present invention.
[00011] FIG.4 illustrates a cross sectional view of the compression damping adjuster unit in accordance with an embodiment of the present invention.
[00012] FIG.5 illustrates an exploded view depicting parts of a rebound damping adjuster unit in accordance with an embodiment of the present invention.
[00013] FIG.6 illustrates a cross sectional view of the rebound damping adjuster unit in accordance with an embodiment of the present invention.
[00014] FIG.7 illustrates a cross sectional view of the suspension system depicting flow of damping fluid through various parts thereof in accordance with an embodiment of the present invention.
[00015] FIG.8 illustrates a detailed view of the damping adjuster assembly depicting flow of damping fluid through various parts thereof in accordance with an embodiment of the present invention.
[00016] FIG.8 illustrates an exploded view depicting damping adjustment markings on compression adjuster housing and corresponding markings on first conversion valve.
DETAILED DESCRIPTION
[00017] The present invention has been made in view of the above circumstances.
[00018] It is an object of the present invention to provide a suspension system including a damping adjuster assembly that is configured for providing varied compression damping characteristics and varied rebound damping characteristics.
[00019] It is another object of the present invention to provide a suspension system including a damping adjuster assembly that is manually adjustable for providing varied compression damping and rebound damping.
[00020] It is still another object of the present invention to provide a suspension system including a damping adjuster assembly for enabling adjustment of compression damping characteristics and rebound damping characteristics independently.
[00021] It is yet another object of the present invention to provide a suspension system including a damping adjuster assembly that is adapted to be functionally connected to a gas canister unit.
[00022] It is one more object of the present invention to provide a suspension system including a damping adjuster assembly that serves as the primary damping generating device.
[00023] Accordingly, the present invention provides a suspension system including a helical spring and a damper unit. The damper unit according to the present invention is a twin tube damper comprising an inner tube and an outer tube. Particularly, the inner tube is divided into a rebound chamber and a compression chamber by means of a portion of a piston assembly provided therein. As per an aspect of the present invention, the piston rod including a piston head which forms the piston assembly merely serves to separate the rebound chamber from the compression chamber and does not serve to allow passage of damping fluid from said compression chamber to the rebound chamber and vice versa unlike conventional damping systems. The passage of the damping fluid from the inner tube to the outer tube and vice versa is allowed through a rod guide provided to support the piston rod and to guide the motion of said piston rod. Further, the suspension system includes a gas canister unit filled with pressurised gas, which serves to reduce lag or cavitation during a rebound stroke. As per an aspect of the present invention, the gas canister unit is disposed away from the damper unit. Said gas canister unit may either be filled with high pressure gas or gas at atmospheric pressure.
[00024] The suspension system as per the present invention is provided with a damping adjuster assembly which enables manual alteration of damping characteristics of said suspension system. As per an embodiment of the present invention, the damping adjuster assembly is located between the damper unit and the gas canister unit, and substantially perpendicularly to a flow path of the damping fluid from the damper unit to the gas canister unit.
[00025] The damping adjuster assembly as per the present invention comprises a rebound damping adjuster unit, and a compression damping adjuster unit. While the damping adjuster assembly is connected to the damper unit at its one end, the other end of the damping adjuster assembly is connected to the gas canister unit. Both the compression damping adjuster unit and the rebound damping adjuster unit are provided with a first conversion valve and a second conversion valve respectively, whose adjustment aids in altering pressure of the damping fluid. Particularly, while damping force in the rebound damping adjuster unit is generated due to a valve pack comprising a plurality of valves and shims, damping force in the compression damping adjuster unit is generated due to said first conversion valve. Damping force generated in said compression damping adjuster unit and said rebound damping adjuster unit corresponds to the altered pressure of damping fluid. Thus, the damping fluid is allowed to flow through the damping adjuster assembly where damping is generated based on pressure of the damping fluid. Thus, change in damping characteristics is achieved by altering pressure of damping fluid. Pressure difference created across said piston rod results in flow of oil between the compression chamber and the rebound chamber through rebound damping adjuster unit and said compression damping adjuster unit, where the damping resistance is generated. Particularly, while the compression damping adjuster unit is configured to enable adjustment in compression damping, the rebound damping adjuster unit is configured to enable adjustment in rebound damping. Thus, the damping adjuster assembly as per the present invention enables separate and independent adjustment for compression damping and rebound damping. Therefore, a rider can based on the terrain in which he/she is riding adjust the damping characteristics of the suspension system.
[00026] Summary provided above explains the basic features of the invention and does not limit the scope of the invention. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to the accompanying drawings.
[00027] Exemplary embodiments detailing features of the suspension system, in accordance with the present invention will be described hereunder with reference to the accompanying drawings. Various aspects of different embodiments of the present invention will become discernible from the following description set out hereunder. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Further, it is to be noted that terms “upper”, “lower”, “right”, “left”, “front”, “forward”, “rearward”, “downward”, “upward”, “top”, “bottom” and like terms are used herein based on the illustrated state or in a standing state of the hybrid vehicle with a driver sitting thereon unless otherwise elaborated. Furthermore, a longitudinal axis refers to a front to rear axis relative to said vehicle, defining a vehicle longitudinal direction; while a lateral axis refers to a side to side, or left to right axis relative to said vehicle, defining a vehicle lateral direction. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
[00028] With reference to FIG.1, a description is made of a suspension system 100 in accordance with an embodiment of the present invention. FIG.1 is a cross sectional view of the suspension system 100 as per an embodiment of the present invention. The suspension system 100 as per the present invention includes a helical spring 101, a damper unit 102, a damping adjuster assembly 103 and a gas canister unit 104. The damper unit 102 as per the present invention is a twin tube damper, including an inner tube 102a and a concentrically disposed outer tube 102b. The inner tube 102a serves to house a piston assembly including a piston rod 102c, and a piston head 102h which separates a compression chamber 102aa from a rebound chamber 102ab formed in the inner tube 102a. Further, said piston assembly as per the present invention does not have any moving valves or passage for flow of damping fluid across said piston rod 102c. In other words, the piston assembly serves as a dummy piston which merely serves to separate the compression chamber 102aa from the rebound chamber 102ab and does not generate damping in said compression chamber 102aa and said rebound chamber 102ab. In the present embodiment, the piston assembly includes the piston head 102h which does not allow damping fluid to flow across the compression chamber 102aa into the rebound chamber 102ab.Further, a rod guide 102d (shown in FIG.1a) is provided around a portion of the piston rod 102c to guide the back and forth movement of the piston rod 102c within the inner tube 102a. The rod guide 102d as per the present embodiment is provided with a plurality of slots/openings 102ds (shown in FIG.1a) in its outer diameter to facilitate damping fluid to flow to an oil seal 102e disposed below said rod guide 102d, thereby facilitating lubrication of said oil seal 102e. Moreover, presence of the rod guide 102d as per the present embodiment also facilitates flow of damping fluid across the rebound chamber 102ab into the outer tube 102b. Further, said piston assembly includes a piston ring 102r for controlling low velocity damping. Particularly, said piston ring 102r serves to reduce friction between said piston rod 102c and the inner tube 102a.
[00029] According to an aspect of the present invention, the outer tube 102b and the inner tube 102a of the suspension system 100 are connected through a connector housing 105 to the damping adjuster assembly 103 and the gas canister unit 104. Thus, the damping fluid is allowed to flow from the outer tube 102b and/or the inner tube 102a, into the damping adjuster assembly 103 and the gas canister unit 104 through the connector housing 105, and back through the connector housing 105 into the outer tube 102b and the inner tube 102a (shown in FIG.7). The gas canister unit 104 as per the present invention includes a diaphragm member 104a which separates gas stored in said gas canister unit from the damping fluid flowing towards the gas canister unit 104. Presence of said diaphragm member 104a ensures the damping fluid flowing from the damping adjuster assembly 103 is allowed to compress the gas in the gas canister unit 104, without coming in contact with the gas. In another embodiment, a floating piston 108 (shown in FIG.1b) may be used to prevent damping fluid from coming in contact with the gas contained in gas canister unit. For example, said floating piston 108 moves based on pressure difference between the damping adjuster assembly 103 and a gas chamber in the gas canister unit 104. In yet another embodiment, no separator may be used, and the damping fluid may be allowed to mix with the gas.
[00030] Particularly, as may be seen in FIG.1 and FIG.2, the damping adjuster assembly 103 includes a rebound damping adjuster unit 103a, and a compression damping adjuster unit 103b, said rebound damping adjuster unit 103a and said compression damping adjuster unit 103b being housed within the connector housing 105. In the present embodiment, the gas canister unit 104 is also housed within the connector housing 105. As per the present invention, compression damping and rebound damping occurs at the compression damping adjuster unit 103b and rebound damping adjuster unit 103a respectively and the compression and rebound damping characteristics can be adjusted/varied as per a rider’s requirement at said compression damping adjuster unit 103b and said rebound damping adjuster unit 103a respectively.
[00031] With reference to FIGs.3-8, the mechanism for adjusting damping characteristics as per the present invention is elaborated. While the adjustment of compression damping is explained with reference to FIGs.3 & 4, the adjustment of rebound damping is explained with reference to FIG. 5 & 6.
[00032] FIG.3 is an exploded view of the compression damping adjuster unit 103b in accordance with an embodiment of the present invention. The compression damping adjuster unit 103b includes a first drive pin 103ba, a first check valve 103bb, a first valve seat 103bc, and a first conversion valve 103bd, said first check valve 103bb, said first valve seat 103bc, and the first conversion valve 103bd being arranged in that order from left to right over the first drive pin 103ba. Further, the first drive pin 103ba is housed in a compression adjuster housing 103be which has a front access orifice A for accessing a first adjustment slot 103bs formed in the first drive pin 103ba. The manual rotation of the first drive pin 103ba can be performed by placing an adjustment tool in said first adjustment slot 103bs and rotating the same. Use of a first set of locking pins 106 (shown in FIG.4) ensures that the first drive pin 103ba is tightly secured to the compression adjuster housing 103be, and that linear motion of the first drive pin 103ba is prevented during rotation. Further, the manual rotation of the first drive pin 103ba causes the rotation of only the conversion valve 103bd. A nut 103bn is used to secure various parts of the compression damping adjuster unit 103b including the first drive pin 103ba, the check valve 103bb, said first valve seat 103bc and the conversion valve 103bd to the compression adjuster housing 103be. Further, in order to prevent leakage of damping fluid to the outside, one or more O-rings are provided. For example, as may be seen in FIG.3 a first O-ring 103fo is provided to be disposed over the first drive pin 103ba to prevent leakage of damping fluid through the first drive pin 103ba into said compression adjuster housing 103be. Further, a second O-ring 103so is provided to be disposed over said compression adjuster housing 103be in order to prevent leakage of damping fluid through the compression adjuster housing 103be to the outside. Similar O-rings may be provided in the rebound damping adjuster unit 103a for preventing leakage of damping fluid.
[00033] During compression stroke, damping fluid from the compression chamber 102aa flows into the rebound damping adjuster unit 103a through the connector housing 105, and from the rebound damping adjuster unit 103a into the compression damping adjuster unit 103b (shown in FIG.7). The rebound damping adjuster unit 103a allows free flow of the damping fluid into the compression damping adjuster unit 103b without any resistance. Some amount of damping fluid also flows into the rebound chamber 102ab from the outer tube 102b. Particularly, the damping fluid enters the compression damping adjuster unit 103b through the first conversion valve 103bd. In the present embodiment, the first conversion valve 103bd is provided with a plurality of compression damping adjustment orifices 103bo, which are circumferentially arranged on said conversion valve 103bd. Each compression damping adjustment orifice of said plurality of compression damping adjustment orifices 103bo is of a different size. For example, in the present embodiment, the size of the plurality of compression damping adjustment orifices 103bo varies from smallest to the largest. While the smallest orifice corresponds to highest level of compression damping, the largest orifice corresponds to the lowest level of compression damping. Further, said first valve seat 103bc is provided with a first alignment orifice 103bf on its circumference which gets aligned with one of said plurality of damping adjustment orifices 103bo when the first drive pin 103ba is rotated. Thus, the damping fluid is allowed to flow through the first alignment orifice 103bf which in turn is aligned with any one of said plurality of damping adjustment orifices 103bo. Pressure is generated over the damping fluid due to the resistance offered by the first conversion valve 103bd. The pressurised damping fluid thus flowing across said first valve seat 103bc further flows through the first check valve 103bb and into the gas canister unit 104. Particularly, the first check valve 103bb expands to allow damping fluid to flow into the gas canister unit 104. Compression damping is generated in the gas canister unit 104 based on the level of pressure created over the damping fluid in the compression damping adjuster unit 103b and the corresponding back pressure generated. Thus, by adjusting the position of the first conversion valve 103bd one can select one of the damping adjustment orifices 103bo which corresponds to any one compression damping setting such as very soft, soft, hard, and very hard which may be indicated on the compression adjuster housing 103be. For example, very hard compression damping setting may be chosen for high speed riding and off road riding. The soft compression setting may be chosen for low speed riding on rough roads.
[00034] When the piston rod 102c begins to pull back during the rebound stroke, the first check valve 103bb begins to close, allowing left over damping fluid in the compression damping adjuster unit 103b to flow into the rebound damping adjuster unit 103a. Some amount of damping fluid from the rebound chamber 102ab also flows into the rebound damping adjuster unit 103a through the outer tube 102b.
[00035] Rebound damping in the rebound damping adjuster unit 103a is explained with reference to FIG.5 & FIG.6. FIG.5 is an exploded view depicting the constituent parts of the rebound damping adjuster unit 103a in accordance with an embodiment of the present invention. The construction of the rebound damping adjuster unit 103a is similar to that of the compression damping adjuster unit 103b. For example, in the present embodiment, the rebound damping adjuster unit 103a includes a second drive pin 103aa, a base valve 103ab, a plurality of valves and shims 103ac disposed on either sides of said base valve 103ab, a second valve seat 103ad, and a second conversion valve 103ae. The plurality of valves and shims 103ac, the base valve 103ab, the second valve seat 103ad and the second conversion valve 103ae are disposed in that order from the left to right over the second drive pin 103aa. Further, the second drive pin 103aa is housed in a rebound adjuster housing 103af which has a front access orifice B for accessing a second adjustment slot (not shown) formed in the second drive pin 103aa. The manual rotation of the second drive pin 103aa can be performed by placing the adjustment tool in said second adjustment slot and rotating the same. Use of a second set of locking pins 107 (shown in FIG.6) ensures that the second drive pin 103aa is tightly secured to the rebound adjuster housing 103af, and that linear motion of the second drive pin 103aa is prevented during rotation. Further, the manual rotation of the second drive pin 103aa causes the rotation of only the second conversion valve 103ae. A nut member 103an is used to secure various parts of the rebound damping adjuster unit 103a including the second drive pin 103aa, the base valve 103ab, the plurality of valves and shims 103ac, the second seat valve 103ad and the second conversion valve 103ae to the rebound adjuster housing 103af. In the present embodiment, the second conversion valve 103ae includes a plurality of rebound damping adjustment orifices 103ao for enabling variation in rebound damping characteristics.
[00036] In order to obtain a change in the rebound damping characteristics of the suspension system, the damping fluid flowing during the rebound stroke into the rebound damping adjuster unit 103a is acted upon at the rebound damping adjuster unit 103a when the second drive pin 103aa is adjusted to correspond to a damping setting in the second conversion valve 103ae. For example, as in the case of the compression adjuster unit 103b, the damping fluid entering the rebound adjuster unit 103a flows through the second conversion valve 103ae. Based on the adjustment of the second drive pin 103aa, the damping fluid is allowed to flow through one rebound damping adjustment orifice of the plurality of rebound damping adjustment orifices 103ao. Since the damping fluid is allowed to flow only through one of said plurality of rebound damping adjustment orifices 103ao, pressure is altered over the damping fluid flowing across the second conversion valve 103ae. Further, the pressurised damping fluid flows across the base valve 103ab which is sandwiched between the plurality of valves and shims 103ac. Rebound damping force is generated at the valve pack including the plurality of valves and shims 103ac. On completion of the rebound stroke, the damping fluid returns to compression chamber 102aa of the inner tube 102a for the cycle of compression damping and rebound damping to continue. As in the case of the compression adjuster housing 103be, the rebound adjuster housing 103af is also provided with markings to indicate different rebound damping settings such very soft, soft, hard and very hard. Hard rebound setting may be chosen for good vehicle handling and stability, and while cornering, while soft rebound setting may be selected for low speed riding and for experiencing plush feel. For example, as may be seen in FIG.8, the compression adjuster housing 103be may be provided with markings 1,2,3 & 4; and the first conversion valve 103bd is provided with markings corresponding to markings 1,2,3,4 in the compression adjuster housing; with 1 corresponding to very hard, 2 corresponding to hard, 3 corresponding to soft and 4 corresponding to very soft. For example, very soft setting may be chosen for low speed riding in extremely rough and broken roads, soft setting may be chosen for riding in typical rural Indian roads, hard setting may be chosen for city riding, and very hard setting may be chosen for high speed riding in highways/race tracks.
[00037] In another embodiment, the compression damping adjuster unit 103b and the rebound damping adjuster unit 103a located between the damper unit 102 and the gas canister unit 104 are configured to provide fixed damping characteristics with the provision provided in the form of first drive pin and the second drive pin being fixed instead of being rotatable for adjustment.
[00038] As is apparent from the above teaching, design and construction of the suspension system as per principles of the present invention permits a rider to manually select the damping settings based on the terrain of riding for good vehicle stability and handling while experiencing good ride feel. Since the present suspension system allows the rider to alter damping characteristics, it is possible to use the present suspension system in any two wheeled and three wheeled vehicle including off road and on road vehicles. Although the present description exemplifies manual adjustment of damping characteristics, it is possible to provide switches for automatic adjustment of damping characteristics, said switches being electrically connected to a controller capable of adjusting damping characteristics based on different vehicle operating conditions and corresponding road conditions.
[00039] While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims:
,CLAIMS:We Claim:
1. A suspension system (100) for a vehicle, said suspension system (100) comprising a damper unit (102), said damper unit (102) comprising an inner tube (102a), an outer tube (102b) and a gas canister unit (104), said inner tube (102a) including a piston rod (102c); and said inner tube (102a) and said outer tube (102b) adapted to hold a damping fluid for circulation through said suspension system (100);
wherein, the suspension system (100) includes a damping adjuster assembly (103) operatively connected to the damper unit (102) at its one end and to the gas canister unit (104) at its other end; and wherein, said adjuster assembly includes a rebound damping adjuster unit (103a) and a compression damping adjuster unit (103b) adapted to be adjusted independently for altering pressure of the damping fluid in order to generate damping force in the rebound damping adjuster unit (103a) and the compression damping adjuster unit (103b) respectively.
2. The suspension system (100) as claimed in claim 1, wherein said compression damping adjuster unit (103b) and said rebound damping adjuster unit (103a) respectively include a first conversion valve (103bd) and a second conversion valve (103ae) adapted to be adjusted independently for altering pressure of the damping fluid in order to generate damping force in the compression damping adjuster unit (103b) and the rebound damping adjuster unit (103a) respectively.
3. The suspension system (100) as claimed in claim 1, wherein said compression damping adjuster unit (103b) and said rebound damping adjuster unit (103a) are adapted to provide fixed damping characteristics.
4. The suspension system (100) as claimed in claim 1, wherein the damper unit (102) is connected to said damping adjuster assembly (103) through a connector housing (105), and wherein said rebound damping adjuster unit (103a) is operatively connected to the inner tube (102a) through the connector housing (105), and said compression damping adjuster unit (103b) is operatively connected to the rebound damping adjuster unit (103a) and the gas canister unit (104) through the connector housing (105).
5. The suspension system (100) as claimed in claim 2, wherein said first conversion valve (103bd) and said second conversion valve (103ae) respectively includes a plurality of compression damping adjustment orifices (103bo) and a plurality of rebound damping adjustment orifices (103ao) which are circumferentially arranged thereon, and wherein size of said plurality of compression damping adjustment orifices (103bo) and said plurality of rebound damping adjustment orifices (103ao) varies from smallest to largest.
6. The suspension system (100) as claimed in claim 1, wherein the compression damping adjuster unit (103b) includes a first drive pin (103ba), a first check valve (103bb), a first valve seat (103bc), and the first conversion valve (103bd); said first check valve (103bb), the first valve seat (103bc), and the first conversion valve (103bd) being arranged in that order from left to right over the first drive pin (103ba).
7. The suspension system (100) as claimed in claim 6 or claim 2, wherein the first drive pin (103ba) is housed in a compression adjuster housing (103be) of said compression damping adjuster unit (103b), and has a front access orifice (A) for accessing a first adjustment slot (103bs) formed in the first drive pin (103ba), and wherein, the first drive pin (103ba) is used for adjusting said first conversion valve (103bd).
8. The suspension system (100) as claimed in claim 1, wherein the rebound damping adjuster unit (103a) comprises a second drive pin (103aa), a base valve (103ab), a plurality of valves and shims (103ac) disposed on either sides of said base valve (103ab), a second valve seat (103ad), and the second conversion valve (103ae).
9. The suspension system (100) as claimed in claim 8 or claim 2, wherein said second drive pin (103aa) is used for adjusting said second conversion valve (103ae).
10. The suspension system (100) as claimed in claim 1, wherein the piston rod (102c) includes a rod guide (102d) to guide back and forth motion of the piston rod (102c) within the inner tube (102a), and wherein said rod guide (102d) includes a plurality of openings to allow passage of the damping fluid between the inner tube (102a) and the outer tube (102b).