WO2024023832A1

WO2024023832A1 - Regulation of fluid flow in suspension dampers

Info

Publication number: WO2024023832A1
Application number: PCT/IN2023/050518
Authority: WO
Inventors: Saurabh Ramchandra Kulkarni; Darshan Vijay Wale; Pawan Ramchandra Kulkarni
Original assignee: Tata Motors Passenger Vehicles Limited
Priority date: 2022-07-27
Filing date: 2023-06-02
Publication date: 2024-02-01

Abstract

A suspension damper for a vehicle includes a cylinder to be filled with a hydraulic fluid, a piston disposed in the cylinder and dividing the cylinder into a first chamber and a second chamber, and a piston rod having a portion disposed in the first chamber. The piston has an opening to allow a first flow of the hydraulic fluid between the first chamber and the second chamber. The piston rod is coupled to the piston to reciprocate along with the piston. An actuatable member extends through a hollow interior of the piston rod. The actuatable member and the piston rod are adapted to allow a second flow of the hydraulic fluid between the first chamber and the second chamber in response to an actuation of the actuatable member.

Description

REGULATION OF FLUID FLOW IN SUSPENSION DAMPERS

FIELD OF INVENTION

[0001] The present invention relates to suspension dampers, and more specifically related to regulating amount of flow of a fluid within a suspension damper.

BACKGROUND OF INVENTION

[0002] A suspension system of a vehicle includes a resilient member, such as a spring, that couples a body of the vehicle with a wheel of the vehicle. The resilient member oscillates when the wheel travels on a bump, to minimize the impact felt on the body. The suspension system also includes a suspension damper that serves to dampen the oscillations of the resilient member and to bring the resilient member to rest quickly by exerting a damping force. An amount of damping force exerted by the suspension damper is directly proportional to the rate of damping of oscillations of the resilient member.

[0003] The suspension damper includes a cylinder filled with a fluid (e.g., hydraulic oil), a piston disposed in the cylinder, and a piston rod partially disposed in the cylinder. The piston divides the cylinder into a first chamber and a second chamber. When the resilient member oscillates, the cylinder reciprocates relative to the piston rod and the piston. The reciprocation causes movement of the fluid between the first chamber and the second chamber. The movement of the fluid progressively reduces amplitude of oscillations of the resilient member and brings the resilient member to rest.

[0004] A damping force exerted by the suspension damper depends on an amount of resistance offered to the movement of the cylinder. The resistance to the movement of the cylinder, in turn, depends on the resistance offered to the movement of the fluid between the first chamber and the second chamber. [0005] Generally, the resistance offered to the movement of the fluid between the first chamber and the second chamber, and consequently the damping force, cannot be varied. However, it may be preferrable to vary the damping force based on a bumpiness of a terrain on which the vehicle travels. For example, when the vehicle is travelling on a relatively plain terrain at a high speed, a high damping force is preferred, as a high damping force ensures that a vertical travel of the wheel is minimal. The minimal wheel travel increases ride stability, which may be necessary during travel at a high speed. Conversely, when the vehicle is travelling on a bumpy terrain, a low damping force is preferred. This is because a large wheel travel, which is caused by the low damping force, ensures that the impact felt on the body of the vehicle is minimal.

SUMMARY OF INVENTION

[0006] A suspension damper for a vehicle includes a cylinder to be filled with a hydraulic fluid, a piston disposed in the cylinder and dividing the cylinder into a first chamber and a second chamber, and a piston rod having a portion disposed in the first chamber. The piston has an opening to allow a first flow of the hydraulic fluid between the first chamber and the second chamber. The piston rod is coupled to the piston. An actuatable member extends through a hollow interior of the piston rod. The actuatable member and the piston rod are adapted to allow a second flow of the hydraulic fluid between the first chamber and the second chamber in response to an actuation of the actuatable member.

BRIEF DESCRIPTION OF DRAWINGS [0007] The features, aspects, and advantages of the subject matter will be better understood with regard to the following description, and accompanying figures. The use of the same reference number in different figures indicates similar or identical features and components.

[0008] Fig. 1 illustrates a suspension strut, according to an implementation of the present subject matter.

[0009] Fig. 2 illustrates a suspension damper, according to an implementation of the present subject matter.

[0010] Fig. 3 illustrates a cylinder having a piston, a piston rod, and an actuatable member disposed therein, according to an implementation of the present subject matter.

[0011] Fig. 4 illustrates a cylinder in a situation in which a clearance is aligned with a second orifice of a piston rod, according to an implementation of the present subject matter.

[0012] Fig. 5 illustrates a perspective view of an actuatable member, according to an implementation of the present subject matter.

[0013] Fig. 6(a) illustrates a cross-sectional view of a damper in a case where a damping setting is adjusted to hard damping, according to an implementation of the present subject matter.

[0014] Fig. 6(b) illustrates a cross-sectional view of a damper in a case where a damping setting is adjusted to moderate damping, according to an implementation of the present subject matter.

[0015] Fig. 6(c) illustrates a cross-sectional view of a damper in a case where a damping setting is adjusted to soft damping, according to an implementation of the present subject matter.

[0016] Fig. 7 illustrates a suspension damper, according to an implementation of the present subject matter. [0017] Fig. 8 illustrates a magnified view of a part of a damper having a clearance and an orifice, according to an implementation of the present subj ect matter.

[0018] Fig. 9 illustrates a magnified view of a part of a damper having an orifice, according to an implementation of the present subject matter.

[0019] Fig. 10 illustrates a perspective view of a portion of an actuatable member, according to an implementation of the present subject matter.

[0020] Fig. 11(a) illustrates a scenario in which a pin is seated on a first recessed portion of an actuatable member, according to an implementation of the present subject matter.

[0021] Fig. 11(b) illustrates a scenario in which a pin is seated on a third raised portion, according to an implementation of the present subject matter.

[0022] Fig. 12 illustrates an exploded view of a pin assembly, according to an implementation of the present subject matter.

[0023] Fig. 13 illustrates a magnified view of a part of a damper having an orifice, according to an implementation of the present subject matter.

DETAILED DESCRIPTION OF INVENTION

[0024] The present subject matter relates to regulating an amount of fluid that flows in a suspension damper. Using techniques of the present subject matter, damping force exerted by the suspension damper can be varied.

[0025] In accordance with an implementation of the present subject matter, the suspension damper includes a cylinder that is to be filled with a hydraulic fluid, such as hydraulic oil. A piston is disposed in the cylinder. The piston divides the cylinder into a first chamber and a second chamber and includes an opening that allows a first flow of the hydraulic fluid between the first chamber and the second chamber. The suspension damper includes a piston rod coupled to the piston and having a portion thereof disposed in the first chamber. The hydraulic fluid may be accommodated in a vacant region of the first chamber that is defined between a wall of the piston rod (also referred to as a piston rod wall) and a wall of the cylinder (also referred to as a cylinder wall).

[0026] In an implementation, the piston rod may be exposed outside of the cylinder through an opening provided at an end of the cylinder. An exposed end of the piston rod may be coupled to a body of the vehicle. The cylinder may be coupled to a resilient member, such as a spring, that oscillates when the vehicle travels on a bump. The oscillation of the resilient member results in reciprocation of the cylinder relative to the piston rod and the piston. The reciprocation may cause the hydraulic fluid to flow between the second chamber and the vacant region.

[0027] An actuatable member may extend through a hollow interior region of the piston rod. The actuatable member may be, for example, a needle that can be rotated. When the actuatable member is actuated, the actuatable member and the piston rod are adapted to allow a second flow of the hydraulic fluid between the first chamber and the second chamber, such as between the vacant region of the first chamber and the second chamber. To allow the second flow, an orifice may extend through the piston rod wall and a clearance may be formed between the piston rod and the actuatable member. The second flow may occur through the orifice and the clearance.

[0028] In an implementation, the clearance is defined by a slit provided on a wall of the actuatable member. The actuation of the actuatable member aligns the slit with the orifice, thereby causing the second flow of the hydraulic fluid through the slit and the orifice.

[0029] In an implementation, the actuatable member has a raised portion on an actuatable member surface. A sealing member extends through the orifice and is seated on the actuatable member. The sealing member may be, for example, a pin. The sealing member can seal the orifice to prevent flow of oil therethrough. For example, the sealing member may include a pin head to seal the orifice. The actuatable member can be actuated such that the sealing member is seated on the raised portion. When the sealing member is seated on the raised portion, the sealing member can no longer seal the orifice. For example, the pin head moves away from the orifice, causing a gap between the pin head and the orifice. Accordingly, when the actuatable member is actuated, the hydraulic fluid can flow through the orifice and the clearance, between the vacant region and the second chamber.

[0030] The present subject matter adjusts the damping force exerted by the suspension damper in an efficient manner. The adjustment can be achieved by simply actuating an actuatable member, which can be performed manually or otherwise, such as using a motorized mechanism.

[0031] The implementations herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting implementations that are illustrated in the accompanying drawings and detailed in the following description. It should be understood, however, that the following descriptions, while indicating preferred implementations and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the implementations herein without departing from the spirit thereof, and the implementations herein include all such modifications. The examples used herein are intended merely to facilitate an understanding of ways in which the implementations herein can be practiced and to further enable those skilled in the art to practice the implementations herein. Accordingly, the examples should not be construed as limiting the scope of the implementations herein. [0032] Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the implementations herein. Also, the various implementations described herein are not necessarily mutually exclusive, as some implementations can be combined with one or more other implementations to form new implementations.

[0033] Referring now to the drawings, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred implementations. Further, for the sake of simplicity, and without limitation, the same numbers are used throughout the drawings to reference like features and components. The implementations herein will be better understood from the following description with reference to the drawings.

[0034] Fig. 1 illustrates a suspension strut 100, according to an implementation of the present subject matter. The suspension strut 100, also referred to as a strut 100, may be used as part of a vehicle (not shown in Fig. 1), such as a car. The strut 100 may couple a body of the vehicle (also referred to as the vehicle body) with a wheel 102 of the vehicle. To this end, the strut 100 includes a body fixture 104 to be coupled to the vehicle body and a wheel fixture 106 coupled to the wheel 102. In an example, the body fixture 104 may be a structure on which the vehicle body is mounted and may be referred to as a body mount or a top mount.

[0035] The strut 100 may prevent vibrations occurring due to travel of the wheel 102 on bumps from getting transferred to the vehicle body, thereby improving rider comfort. For instance, when the wheel 102 is travelling over a bump, the wheel 102 may travel in a vertical direction, towards and away from the vehicle body. The strut 100 may prevent or reduce movement of the vehicle body in the vertical direction due to the vertical travel of the wheel 102. To this end, the strut 100 may include a resilient member 108 that oscillates during the vertical travel of the wheel 102. The resilient member 108 may be, for example, a spring that expands and contracts during the vertical travel of the wheel 102. Hereinafter, the resilient member 108 will be explained with reference to a spring, and will be referred to as the spring 108. The spring 108 may support the body fixture 104. For example, the body fixture 104 may be seated on a top end of the spring 108.

[0036] The strut 100 may include a suspension damper 110, also referred to as a damper 110, to dampen the oscillations of the spring 108 and to bring the spring 108 to rest quickly. The damper 110 may be coupled to the spring 108, such as a bottom of the spring 108. For example, the spring 108 may be seated on a spring seat 114 of the damper 110. The damper 110 includes a strut housing 112 having a piston (not shown in Fig. 1) disposed therein and filled with a hydraulic fluid, such as hydraulic oil. A piston rod (not shown in Fig. 1) is coupled to the piston and is partially disposed in the strut housing 112. A portion of the piston rod that is exposed outside of the strut housing 112 is enclosed by the spring 108 and a dust cover 116. The exposed portion of the piston rod is also coupled to the body fixture 104, and therefore, to the vehicle body.

[0037] During the vertical travel of the wheel 102, the spring 108 oscillates (i.e., expands and contracts), with a top portion of the spring 108 (which is coupled to the body fixture 104) remaining substantially stationary. Further, the strut housing 112, which is coupled to the spring 108, reciprocates. The strut housing 112 may reciprocate relative to the piston rod and the piston. The reciprocation of the strut housing 112 may be resisted by the hydraulic fluid in the strut housing 112. The resistance gradually reduces amplitude of reciprocation of the strut housing 112 (and therefore, reduces the amplitude of oscillations of the spring 108), and eventually brings the spring 108 to rest. Thus, it can be seen that the damper 110 exerts a damping force on the spring 108 and dampens the oscillations of the spring 108.

[0038] Although the suspension strut 100 is explained with reference to a spring suspension (in which the resilient member 108 is a spring), the techniques of the present subject matter can also be utilized in an air suspension. In case of the air suspension, the resilient member 108 may be a bellows.

[0039] Fig. 2 illustrates the damper 110, according to an implementation of the present subject matter. The damper 110 includes the strut housing 112. The strut housing 112 may be substantially cylindrical. The strut housing 112 includes a cylinder 202 that is filled with a hydraulic fluid, such as hydraulic oil. Hereinafter, the hydraulic fluid is explained with reference to hydraulic oil. Further, the hydraulic oil will be referred to as ‘oil’. The cylinder 202 may have a piston 204 disposed therein. The piston 204 may divide the cylinder 202 into a first chamber 206 and a second chamber 208. The piston 204 includes an opening 210 that allows the oil to flow between the first chamber 206 and the second chamber 208. The opening 210 may be offset from a centre of the piston 204. The piston 204 may include an additional opening 212, to facilitate more oil to flow between the first chamber 206 and the second chamber 208.

[0040] The piston 204 may be coupled to a piston rod 214. The piston rod 214 may extend in a height direction of the cylinder 202. A portion of the piston rod 214 may be disposed in the cylinder 202 and another portion of the piston rod 214 may be exposed outside the cylinder 202. The piston rod 214 may extend from outside of the cylinder 202, through the cylinder 202, to the piston 204. A portion of the piston rod 214 may be disposed in the first chamber 206. A vacant region 216 exists between a wall 218 of the piston rod 214 (also referred to as the piston rod wall 218) and a wall 220 of the cylinder 202 (also referred to as the cylinder wall 220). The vacant region 216 is part of the first chamber 206 and may accommodate oil.

[0041] An exposed end 221 of the piston rod 214 that is exposed outside the cylinder 202 may be coupled to the body fixture 104 (not shown in Fig. 2), as explained with reference to Fig. 1. Further, the strut housing 112, and consequently the cylinder 202, may be coupled to the spring 108 (not shown in Fig. 2). For example, as explained earlier, a bottom of the spring 108 maybe seated on the spring seat 114 (not shown in Fig. 2) of the damper 110. The strut housing 112, and consequently the cylinder 202, may also be coupled to the wheel fixture 106 (not shown in Fig. 2).

[0042] By virtue of the coupling of the strut housing 112 with the spring 108, the strut housing 112 reciprocates when the spring 108 oscillates. For example, a first end 222 of the cylinder 202 moves towards and away from the piston 204 and the piston rod 214. The reciprocation of the strut housing 112 may also be referred to as the reciprocation of the cylinder 202. During the reciprocation, oil flows between the first chamber 206 and the second chamber 208. That is, oil flows from one side of the piston 204 to the other side thereof and vice-versa through the openings 210 and 212. For instance, when the first end 222 moves towards the piston 204, oil moves from the second chamber 208 to the vacant region 216 and when the first end 222 moves away from the piston 204, oil moves from the vacant region 216 to the second chamber 208. The flow of oil between the first chamber 206 and the second chamber 208 through the openings 210 and 212 may be referred to as a first flow of the oil.

[0043] The strut housing 112 also includes another cylinder 224 that encloses the cylinder 202. The other cylinder 224 acts as a buffer to temporarily store the oil pushed from the cylinder 202. Oil gets pushed from the cylinder 202 when the first end 222 approaches the piston 204 during reciprocation of the cylinder 202. The oil stored in the other cylinder 224 is pushed back into the cylinder 202 when the first end 222 moves away from the piston 204. The flow of the oil between the cylinder 202 and the other cylinder 224 is regulated by a valve assembly 226, also referred to as a base valve assembly 226. The other cylinder 224 may also be referred to as a reserve cylinder. Further, the cylinder 202 may be referred to as a pressure cylinder. An upward movement of the cylinder 202 (i.e., the first end 222 approaching the piston 204) may be referred to as a compression stroke and a downward movement of the cylinder 202 may be referred to as a rebound stroke.

[0044] A resistance offered to the flow of the oil between the vacant region 216 and the second chamber 208 resists the reciprocation of the cylinder 202. Accordingly, a greater resistance to the flow of the oil causes a faster damping of reciprocations of the cylinder 202 (and consequently, a faster damping of oscillations of the spring 108). The damper 110 varies resistance offered to the flow of the oil, thereby varying the damping force. The manner in which the variable damping force is achieved, in an implementation, is explained below.

[0045] To achieve a variable damping force, the piston rod 214 is made hollow. Further, an actuatable member 228 is provided that extends through a hollow interior of the piston rod 214. The actuation of the actuatable member 228 may regulate flow of the hydraulic fluid between the vacant region 216 and the second chamber 208. The actuatable member 228 may be coaxial to the piston rod 214 and may extend along a length of the piston rod 214 through the hollow interior. In an implementation, the actuatable member 228 may be a component having a circular cross-sectional area. For example, the actuatable member 228 maybe a needle. Further, the actuation of the actuatable member 228 may be a rotation. Hereinafter, the actuatable member 228 will be explained with reference to a scenario in which the actuation of the actuatable member 228 is rotation.

[0046] The actuatable member 228 and the piston rod 214 are adapted to allow a second flow of the oil between first chamber 208 (e.g., the vacant region 216 of the first chamber 208) and the second chamber 208 when the actuatable member 228 is actuated. The second flow of the oil is in addition to the first flow of the oil, which occurs through the openings 210 and 212 of the piston 204. Thus, the rotation of the actuatable member 228 increases the amount of oil flowing between the vacant region 216 and the second chamber 208. Since an increased amount of fluid flow between the chambers reduces the resistance offered to the reciprocation of the piston rod 214, the damping force is reduced on rotation of the actuatable member 228. To achieve the second flow, a first orifice 230 is provided on the piston rod wall 218. Further, a clearance 232 is provided between the piston rod 214 and the actuatable member 228. The second flow may occur through the first orifice 230 and the clearance 232. The first orifice 230 and the clearance 232 are explained with reference to Fig. 3.

[0047] Fig. 3 illustrates the cylinder 202 having the piston 204, the piston rod 214, and the actuatable member 228 disposed therein, according to an implementation of the present subject matter. The first orifice 230 may extend in a radial direction on the piston rod wall 218. For instance, the first orifice 230 may extend from the vacant region 216 on one end to the hollow interior region of the piston rod 214 at the other end. The clearance 232 may exist for a part of the lengths of the actuatable member 228 and the piston rod 214. In the remaining lengths of the actuatable member 228 and the piston rod 214, the clearance may not be provided, for example, by making the diameter of the actuatable member 228 substantially same as an inner diameter of the piston rod 214. The clearance 232 may extend from an end 302 of the actuatable member 228 that faces the second chamber 208. The end 302 may also be referred to as the first actuatable member end 302. In an implementation, the clearance 232 is achieved by providing a slit on a surface of the actuatable member 228. The slit extends in an axial direction of the actuatable member 228 from the first actuatable member end 302 and ends before the other end 304 of the actuatable member 228. The other end 304 may be away from the cylinder 202 (e.g., disposed outside the cylinder 202) and may be referred to as the second actuatable member end 304.

[0048] In an implementation, the actuatable member 228 may extend into the second chamber 208, and the first actuatable member end 302 may be disposed in the second chamber 208. Accordingly, the clearance 232, which extends from the first actuatable member end 302, is in fluid communication with the second chamber 208. Further, the clearance 232 can directly receive oil from, and supply oil to, the second chamber 208. The actuatable member 228 may extend into the second chamber 208 through an opening (not shown in Fig. 3) provided in the piston 204. The opening may extend through the length of the piston 204 and around a centre of the piston 204.

[0049] The actuatable member 228 may be rotated such that the slit may align with the first orifice 230. When the slit is aligned with the first orifice 230, the clearance 232 and the first orifice 230 form a continuous passage that extends from the second chamber 208 to the vacant region 216, as illustrated. Thus, oil can flow between the vacant region 216 and the second chamber 208 through the clearance 232 and the first orifice 230, thereby allowing the second flow. As explained earlier, allowing the second flow, in addition to the previously- existing first flow, reduces the damping force exerted by the damper 110. Thus, the damping force can be reduced by rotating the actuatable member 228 by a predetermined angle. [0050] The rotation of the actuatable member 228 can be performed manually or by another means, such as using a motor. To allow a manual rotation of the actuatable member 228, in an example, a knob 306 may be coupled to the actuatable member 228. The knob 306 may be coupled to the second actuatable member end 304. The knob 306 may be disposed, for example, in an engine compartment (not shown in Fig. 3) of the vehicle. Thus, when the driver of the vehicle desires a lower damping force, such as when the vehicle is about to travel on a bumpy terrain, the driver may rotate the knob 306 in a particular direction, such as clockwise, by a predetermined angle. When the lower damping force is no longer required, such as when the vehicle is about to travel on a relatively plain terrain, the driver may rotate the knob 306 in the opposite direction, such as counter-clockwise. In an example, the rotation of the actuatable member 228 may be achieved with a motorized mechanism. For instance, the vehicle may be provided with a motor coupled to the second actuatable member end 304. A control for the motor may be provided, for example, in a dashboard (not shown in Fig. 3) of the vehicle. Accordingly, the driver may operate the motor when an adjustment of the damping force is required.

[0051] In an example, the first orifice 230 may have the shape of a circle in cross-section and the slit may have the shape of a semi-circle in cross-section. In some implementations, in addition to the first orifice 230, the piston rod 214 may have an additional orifice, as will be explained with reference to Fig. 4.

[0052] Fig. 4 illustrates the cylinder 202 in a situation in which the clearance 232 is aligned with a second orifice 404 of the piston rod 214, according to an implementation of the present subject matter. Similar to the first orifice 230, the second orifice 404 may extend through the piston rod wall 218 radially. The second orifice 404 may be displaced from the first orifice 230 (not shown in Fig. 4) in the circumferential direction of the piston rod 214. For example, the second orifice 404 may be circumferentially displaced from the first orifice 230 by a particular angle, such as 45°. The clearance 232 may be aligned with the second orifice 404 when the actuatable member 228 is rotated by a predetermined angle. When the clearance 232 is aligned with the second orifice 404, the second flow of oil between the vacant region 216 and the second chamber 208 may be achieved through the clearance 232 and the second orifice 404.

[0053] The predetermined angle by which the actuatable member 228 is to be rotated for aligning the clearance 232 with the second orifice 404 may be different than the angle by which the actuatable member 228 has to be rotated for aligning the clearance 232 with the first orifice 230. For example, the actuatable member 228 may have to be rotated by 45° clockwise from its mean position for aligning the clearance 232 with the first orifice 230, while the actuatable member 228 may have to be rotated by 90° clockwise from its mean position for aligning the clearance 232 with the second orifice 404.

[0054] In an implementation, the amount of second flow of oil for alignment of the clearance 232 with the second orifice 404 may be more than the second flow of oil for alignment of the clearance 232 with the first orifice 230. The amount of second flow may be made larger, for example, by making diameter of the second orifice 404 more than that of the first orifice 230.

[0055] Since the amounts of second flow are different for different alignments, the damping force generated for the different alignments are different. Thus, different damping forces can be achieved with different degrees of rotations of the actuatable member 228. In an example, a damping achieved with no rotation of the actuatable member 228 (i.e., when the actuatable member 228 is at its mean position) may be referred to as hard damping, as the amount of oil flow between the vacant region 216 and the second chamber 208 is minimal, and consequently, the damping force is high, in such a case. Further, a damping achieved for a rotation of the actuatable member 228 such that the clearance 232 is aligned with the second orifice 404 may be referred to as soft damping, as a maximum amount of oil flows between the vacant region 216 and the second chamber 208 in such a case. Further, a damping achieved for a rotation of the actuatable member 228 such that the clearance 232 is aligned with the first orifice 230 may be referred to as moderate damping.

[0056] Fig. 5 illustrates a perspective view of the actuatable member 228, according to an implementation of the present subject matter. The actuatable member 228 may be rod-shaped. In an example, the actuatable member 228 may be a needle, with a head of the needle disposed outside of the cylinder 202 (not shown in Fig. 5) and an opposite end of the needle (e.g., the first actuatable member end 302) disposed in the cylinder 202. The actuatable member 228 includes a slit 502 on its surface. When the actuatable member 228 extends through the piston rod 214 (not shown in Fig. 5), the slit 502 along with the inner surface of the piston rod 214defines the clearance 232. The slit 502 may extend in an axial direction of the actuatable member 228.

[0057] Fig. 6(a) illustrates a cross-sectional view of the damper 110 in a case where a damping setting is adjusted to hard damping, according to an implementation of the present subject matter. As illustrated, the first orifice 230 is circumferentially displaced from the second orifice 404 on the piston rod 214. As illustrated, the slit 502 is aligned neither with the first orifice 230 nor with the second orifice 404. Accordingly, the second flow of oil is absent. The position of the actuatable member 228 as illustrated may be a mean position of the actuatable member 228. [0058] Fig. 6(b) illustrates a cross-sectional view of the damper 110 in a case where the damping setting is adjusted to moderate damping, according to an implementation of the present subject matter. Here, the slit 502 is aligned with the first orifice 230, thereby allowing a moderate level of second flow and achieving the moderate damping. To adjust the damping setting to moderate damping, the actuatable member 228 may be rotated from its mean position in a particular direction, such as counter-clockwise, by a predetermined angle, such as 90°.

[0059] Fig. 6(c) illustrates a cross-sectional view of the damper 110 in a case where the damping setting is adjusted to soft damping, according to an implementation of the present subject matter. Here, the slit 502 is aligned with the second orifice 404, thereby allowing a high level of second flow and achieving the soft damping. To adjust the damping setting to soft damping, the actuatable member 228 may be rotated from its mean position in a particular direction, such as counter-clockwise, by a predetermined angle, such as 180°.

[0060] Although the piston rod 214 is explained as having two orifices, in some examples, more orifices of different diameters may be provided on the piston rod 214. Accordingly, the number of damping settings may be increased.

[0061] In the above explanation, the second flow is explained as being achieved by providing a slit on a surface of an actuatable member. In some implementations, the second flow can be achieved by providing a sealing member in the orifice of a piston rod and raised portions on the surface of the actuatable member, as will be explained below.

[0062] Fig. 7 illustrates a damper 700, according to an implementation of the present subject matter. In the below explanation, details of parts of the damper 700 that are similar to corresponding parts of the damper 110, such as the cylinder 702 and the piston 704, are not repeated for the sake of brevity. The damper 700 includes the cylinder 702 and the piston 704 disposed in the cylinder 702. The piston 704 divides the cylinder 702 into a first chamber 706 and a second chamber 708. Oil can flow between the first chamber 706, such as a vacant region 710 of the first chamber 706, and the second chamber 708 through piston openings 712-1 and 712-2. Such a flow may be referred to as the first flow.

[0063] A piston rod 714 has a portion thereof disposed in the first chamber 706 and is coupled to the piston 704. The piston rod 714 is hollow and an actuatable member 716 extends through a hollow interior region of the piston rod 714. The actuatable member 716 maybe coaxial to the piston rod 714. The piston rod 714 and the actuatable member 716 may be adapted to allow a second flow of oil between the first chamber 706, such as the vacant region 710, and the second chamber 708 when the actuatable member 716 is actuated. The actuatable member 716 may be a rotatable member, similar to the actuatable member 228, and the actuation may be rotation.

[0064] To achieve the second flow, a first orifice (not shown in Fig. 7) may extend through a wall 718 of the piston rod 714, also referred to as the piston rod wall 718. The first orifice may correspond to the first orifice 230. Through the first orifice, a sealing member 720 may extend. The first orifice may extend in a radial direction of the piston rod 714. The first orifice may fluidly connect the vacant region 710 with the hollow interior region of the piston rod 714. Further, a clearance (not shown in Fig. 7) may be provided between the piston rod 714 and the actuatable member 716. The second flow may occur through the first orifice and the clearance. [0065] Fig. 8 illustrates a magnified view of a part of the damper 700 having the clearance 802 and the first orifice 804, according to an implementation of the present subject matter. The clearance 802 may extend in an axial direction of the actuatable member 716 up to a part of the lengths of the actuatable member 716 and the piston rod 714. For instance, the clearance 802 may extend from an end 806 of the actuatable member 716 that faces the second chamber 708 and may end before the other end of the actuatable member 716. The remaining lengths of the actuatable member 716 and the piston rod 714 may be made free of the clearance between them, for example, by making the diameter of the actuatable member 716 substantially same as the inner diameter of the piston rod 714. In an example, the clearance 802 may be defined by providing a recessed portion (not shown in Fig. 8) on a surface of the actuatable member 716. The end 806 of the actuatable member 716 that faces the second chamber 708 may be referred to as a first actuatable member end 806. The first actuatable member end 806 may receive oil from the second chamber 708 through a central opening 808 provided in the piston 704. The clearance 802 may extend from the first actuatable member end 806 until a region of the piston rod 714 that has the first orifice 804. Accordingly, oil from the second chamber 708 can reach until the bottom of the first orifice 804.

[0066] A flow of the oil from the second chamber 708 through the clearance 802 to the vacant region 710 may be regulated by the sealing member 720, which extends through the first orifice 804 and that can seal the first orifice 804. The sealing member 720 may be, for example, a pin. The sealing member 720 may be seated on the actuatable member 716. When the sealing member 720 is lifted away from the first orifice 804, the sealing member 720 no longer seals the first orifice 804, and allows the second flow of oil through the first orifice 804. The usage of the sealing member 720 for sealing and opening the first orifice 804 will be explained below with reference to a scenario in which the sealing member 720 is a pin. [0067] Fig. 9 illustrates a magnified view of a part of the damper 700 having the first orifice 804, according to an implementation of the present subject matter. The pin 720 is seated on the actuatable member 716 and extends through the first orifice 804 up to the vacant region 710. In an implementation, a pin cage 902 may be provided in the first orifice 804. The pin cage 902 may be attached to the piston rod wall 718 and may be hollow. Through the hollow interior of the pin cage 902, the pin 720 may extend and the oil may flow. The pin 720 includes a pin head 906 having a larger diameter than a body 908 of the pin 720 and facing the vacant region 710. When the pin head 906 is seated on a top portion 910 of the pin cage 902, the hollow interior of the pin cage 902 is sealed, and consequently, the first orifice 804 is sealed. Accordingly, when the pin head 906 is seated on the top portion 910, the second flow of oil is stopped.

[0068] When the pin head 906 is lifted away from the first orifice 804 (e.g., when the pin head 906 is lifted away from the top portion 910), a gap exists between the pin head 906 and the top portion 910. Through this gap, oil may flow between the vacant region 710 and the hollow interior of the pin cage 902. Accordingly, when the pin head 906 is lifted away from the first orifice 804, the second flow of oil is allowed, between the vacant region 710 and the second chamber 708 (not shown in Fig. 9). To lift the pin head 906, a raised portion (not shown in Fig. 9) may be provided on a surface of the actuatable member 716. The pin head 906 maybe lifted when the actuatable member 716 is rotated such that the pin 720 is seated on the raised portion.

[0069] Fig. 10 illustrates a perspective view of a portion of the actuatable member 716, according to an implementation of the present subject matter. The actuatable member 716 includes the first actuatable member end 806 that faces the second chamber 708 when the actuatable member 716 is disposed in the cylinder 702 (not shown in Fig. 10). Further, when the actuatable member 716 is disposed in the cylinder 702, the pin 720 (not shown in Fig. 10) may be seated on a surface of the actuatable member 716. The actuatable member 716 may be rotatable relative to the pin 720. When such a rotation happens, a portion of the actuatable member 716 on which the pin 720 is seated changes. [0070] The actuatable member 716 includes a plurality of recessed portions on its surface that are displaced from each other in a circumferential direction of the actuatable member 716. The pin 720 may be seated on one of the plurality of recessed portions. The recessed portion on which the pin 720 is seated may be changed by actuating the actuatable member 716.

[0071] Each recessed portion may be at a different height. A first recessed portion 1002 may be at a lower height as compared to a second recessed portion 1004. For example, the second recessed portion 1004 is at a greater height from an axis of the actuatable member 716 as compared to the first recessed portion 1002. Accordingly, the second recessed portion 1004 may also be referred to as a first raised portion 1004. When the pin 720 is seated on the first recessed portion 1002, the pin head 906 may be in contact with the top portion 910 of the pin cage 902. When the pin 720 is seated on the second recessed portion 1004, the pin 720 may be moved away from the first orifice 804, and the pin head 906 may no longer be in contact with the top portion 910. Accordingly, when the second flow of oil is to be allowed, the actuatable member 716 is to be rotated such that the pin 720 gets seated on the second recessed portion 1004. When the second flow is to be stopped, the actuatable member 716 may be rotated such that the pin 720 gets seated on the first recessed portion 1002.

[0072] In an implementation, in addition to the first recessed portion 1002 and the second recessed portion 1004, a third recessed portion 1006 may also be provided on the surface of the actuatable member 716. The third recessed portion 1006 may also be referred to as the second raised portion 1006. The third recessed portion 1006 may be displaced from the other recessed portions in a circumferential direction of the actuatable member 716. The actuatable member 716 may be rotated such that the pin 720 gets seated on the third recessed portion 1006. The third recessed portion 1006 may be at a greater height as compared to the second recessed portion 1004. Accordingly, when the pin 720 is seated on the third recessed portion 1006, a second gap that is formed between the pin head 906 and the top portion 910 is greater than a first gap formed between the pin head 906 and the top portion 910 when the pin 720 is seated on the second recessed portion 1004. Thus, a greater amount of oil can flow between the second chamber 708 and the vacant region 710 when the pin 720 is seated on the third recessed portion 1006.

[0073] In an implementation, the actuatable member 716 may also include a third raised portion 1008. The third raised portion 1008 may not be a recessed portion, and may be at a greater height than the second raised portion 1006. Further, the third raised portion 1008 may be circumferentially displaced from the other raised portions. The actuatable member 716 may be rotated such that the pin 720 gets seated on the third raised portion 1008. Since the third raised portion 1008 is at a greater height than the other raised portions, an amount of oil flow for seating of the pin 720 on the third raised portion 1008 may be more than that for seating on the other raised portions.

[0074] In an example, the pin 720 is seated on the first recessed portion 1002 when the actuatable member 716 is at its mean position. Further, the pin 720 is seated on the second recessed portion 1004 when the actuatable member 716 is rotated by 45° from its mean position, and is seated on the third recessed portion 1006 when the actuatable member 716 is rotated by 90° from its mean position. Thus, by rotating the actuatable member 716, the amount of additional oil that can flow between the vacant region 710 and the second chamber 708 can be controlled. The rotation of the actuatable member 716 may be performed using a knob or a motor, similar to the rotation of the actuatable member 228.

[0075] Fig. 11(a) illustrates a scenario in which the pin 720 is seated on the first recessed portion 1002 of the actuatable member 716, according to an implementation of the present subject matter. As illustrated, the pin head 906 contacts the top portion 910 of the pin cage 902, thereby preventing the second oil flow.

[0076] Fig. 11(b) illustrates a scenario in which the pin 720 is seated on the third recessed portion 1006, according to an implementation of the present subject matter. A second gap 1104 is formed between the pin head 906 and the first orifice 804, which allows the second oil flow. The second gap 1104 is larger than a first gap 1102 (not shown in Fig. 11(b)) that is formed between the pin head 906 and the first orifice 804 when the pin 720 is seated on the second recessed portion.

[0077] Fig. 12 illustrates an exploded view of a pin assembly 1200, according to an implementation of the present subject matter. The pin assembly 1200 includes the pin 720 and the pin cage 902. The pin 720 includes the pin head 906 at its top end and a pin bottom 1202 at its bottom end. The pin bottom 1202 gets seated on the surface of the actuatable member 716 (not shown in Fig. 12). The pin cage 902 is hollow and can accommodate the pin 720. The oil can flow in the gap between the inner surface of the pin cage 902 and the pin 720. The top portion 910 can accommodate the pin head 906. The pin head 906 may contact the top portion 910 to seal the first orifice 804 and may be lifted away from the top portion 910 to open the first orifice 804. [0078] The pin assembly 1200 further includes a spring 1204 accommodated in the pin cage 902. The spring 1204 surrounds the pin 720 and may be attached to the pin 720. The spring 1204 may be such that the spring 1204 may be in a relaxed state when the pin head 906 is in contact with the top portion 910 and that the spring 1204 may be in an expanded state when the pin head 906 is lifted away from the top portion 910. Thus, the spring 1204 may tend to push the pin head 906 towards the top portion 910 (i.e., push the pin 720 towards the surface of the actuatable member 716), so as to return to its relaxed state. Since the spring 1204 tends to push the pin 720 towards the surface of the actuatable member 716, the spring 1204 ensures that the pin bottom 1202 maintains contact with the surface even after rotation of the actuatable member 716. For example, when the actuatable member 716 is rotated from a position at which the pin 720 is seated on the third recessed portion 1006, the spring 1204 may push the pin 720 downwards, thereby causing the pin 720 to come in contact with the first recessed portion 1002. Thus, a floating state of the pin 720, at which the pin 720 is not in contact with any of the recessed portions, is prevented.

[0079] In an implementation, instead of the spring 1204, an O-ring may be used to push the pin 720 against the surface of the actuatable member 716, as will be explained below:

[0080] Fig. 13 illustrates a magnified view of a part of the damper 700 having the first orifice 804, according to an implementation of the present subject matter. An O-ring 1302 is provided between an inner surface of the cylinder 702 and the pin head 906. In an implementation, a cup 1304 may be disposed in the cylinder 702. The cup 1304 may surround an end of the piston rod 714. A clearance 1306 may be present between the cup 1304 and the inner surface of the cylinder 702. The O-ring 1302 may be attached to the pin head 906 and the inner surface of the cup 1304. [0081] The O-ring 1302 may be in a relaxed state when the pin head 906 is in contact with the top portion 910 and may get compressed when the pin 720 gets lifted. While in the compressed state, the O-ring 1302 pushes the pin 720 towards the surface of the actuatable member 716, so as to return to its relaxed state. Accordingly, the O-ring 1302 enables the pin 720 to contact the surface of the actuatable member 716 for all rotations of the actuatable member 716.

[0082] Although a member used for ensuring contact between the surface of the actuatable member 716 and the pin 720 are explained as being a spring or an O-ring, other types of members may be used for this purpose. The member used for this purpose may be generally referred to as a biasing member, as such a member biases the pin 720 against the surface of the actuatable member 716.

[0083] The present subject matter also provides a method for controlling damping force exerted by a damper, such as the damper 110 or damper 700. The damper has a cylinder, such as the cylinder 202 or the cylinder 702, filled with a hydraulic fluid and a piston, such as the piston 204 or the piston 704 disposed in the cylinder 702. The piston divides the cylinder into a first chamber and a second chamber, and has an opening defining a primary flow of the hydraulic fluid between the first chamber and the second chamber. A piston rod, such as the piston rod 214 or 714, is coupled to the piston. The method includes providing a secondary flow of hydraulic fluid between the first chamber and the second chamber. The secondary flow is defined by an orifice, such as the first orifice 230 or the first orifice 804, provided in the piston rod. The method also includes controlling the secondary flow based on actuation of an actuatable member, such as the actuatable member 228 or the actuatable member 716, configured in communication with the first orifice. [0084] Although adjustment of damping settings is explained as being achieved by rotation of the actuatable member, in some implementations, the adjustment may be achieved by a translational movement of the actuatable member. Further, in some implementations, both rotation and translational movement may be used for adjustment of the damping settings.

[0085] The present subject matter enables adjusting damping force of a suspension damper based on bumpiness of a terrain on which a vehicle travels. The damping force can be adjusted simply by actuating, such as rotating, an actuatable member. The adjustment of the damping forces can be achieved using two alternative mechanisms. In the first mechanism, the damping forces are adjusted by aligning a slit provided on the actuatable member with an orifice in the piston rod. In the second mechanism, the damping forces are adjusted by adjusting a position of a sealing member provided in the orifice.

[0086] Since the clearance established between the actuatable member and the piston rod is exposed to the second chamber of the piston, oil can be directly exchanged between the clearance and the second chamber. Therefore, a separate mechanism to convey oil between the second chamber and the clearance need not be provided. Thus, the present subject matter provides a simple mechanism for achieving the second flow of oil between the vacant region and the second chamber.

[0087] The foregoing description of the specific implementations will so fully reveal the general nature of the implementations herein that others can, by applying current knowledge, readily modify and/or adapt for various applications without departing from the generic concept, and, therefore, such modifications and adaptations should and are intended to be comprehended within the meaning and range of equivalents of the disclosed implementations. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the implementations herein have been described in terms of preferred implementations, those skilled in the art will recognize that the implementations herein can be practiced with modification within the spirit and scope of the implementations as described herein.

Claims

CLAIMS:

1. A suspension damper for a vehicle, the suspension damper comprising: a cylinder for receiving a hydraulic fluid; a piston disposed in the cylinder and dividing the cylinder into a first chamber and a second chamber, the piston having an opening to allow a first flow of the hydraulic fluid between the first chamber and the second chamber; a piston rod having a portion disposed in the first chamber, the piston rod being coupled to the piston; and an actuatable member extending through a hollow interior of the piston rod, wherein the actuatable member and the piston rod are adapted to allow a second flow of the hydraulic fluid between the first chamber and the second chamber in response to an actuation of the actuatable member.

2. The suspension damper as claimed in claim 1, wherein the clearance extends from an end of the actuatable member that faces the second chamber.

3. The suspension damper as claimed in claim 1, wherein the piston rod defines a vacant region in the first chamber between a piston rod wall and a cylinder wall, wherein the piston rod has a first orifice extending through the piston rod wall, wherein a clearance exists between the actuatable member and the piston rod, and wherein the actuation of the actuatable member regulates flow of the hydraulic fluid between the vacant region and the second chamber through the first orifice and the clearance.

4. The suspension damper as claimed in claim 3, wherein the clearance is defined by a slit provided on a surface of the actuatable member, and wherein the actuatable member is actuatable to align the slit with the first orifice.

5. The suspension damper as claimed in claim 3, wherein the slit extends from a first actuatable member end of the actuatable member facing the second chamber, and wherein the actuatable member is actuatable to substantially align the slit with the first orifice.

6. The suspension damper as claimed in claim 5, wherein the piston rod has a second orifice extending through the piston rod wall, and wherein the actuatable member is actuatable to substantially align the actuatable member with the second orifice.

7. The suspension damper as claimed in claim 6, wherein a diameter of the second orifice is greater than that of the first orifice.

8. The suspension damper as claimed in claim 3, wherein the actuatable member has a first raised portion on an actuatable member surface, wherein the suspension damper comprises: a sealing member extending through the first orifice to seal the first orifice and seated on the actuatable member, wherein the actuatable member is actuatable to cause the sealing member to be seated on the first raised portion, and wherein, in response to seating of the sealing member on the first raised portion, the sealing member is moved away from the first orifice, causing flow of the hydraulic fluid through the first orifice and the first clearance.

9. The suspension damper as claimed in claim 8, wherein the sealing member is a pin having a pin head to seal the first orifice, and wherein, in response to seating of the sealing member on the first raised portion, the pin head moves away from the first orifice.

10. The suspension damper as claimed in claim 9, wherein the actuatable member has a second raised portion of a greater height than the first raised portion, and wherein in response to seating of the sealing member on the second raised portion, a second gap is formed between the pin head and the first orifice, the second gap being larger than a first gap that is formed between the pin head and the first orifice when the sealing member is seated on the first raised portion.

11. The suspension damper as claimed in claim 8, comprising a biasing member to bias the sealing member against the actuatable member surface.

12. The suspension damper as claimed in claim 11, wherein the biasing member is one of: a spring disposed in the first orifice, surrounding the sealing member, and attached to the sealing member; and an O-ring disposed between the sealing member head and the cylinder wall.

13. A suspension strut for a vehicle, the suspension strut comprising: a suspension damper comprising: a cylinder to be filled with a hydraulic fluid; a piston disposed in the cylinder and dividing the cylinder into a first chamber and a second chamber, the piston having an opening to allow flow of the hydraulic fluid between the first chamber and the second chamber; a piston rod having a portion disposed in the first chamber and defining a vacant region in the first chamber between a piston rod wall and a cylinder wall, the piston rod being coupled to the piston, wherein the piston rod is hollow and has a first orifice extending through the piston rod wall; and an actuatable member extending through a hollow interior of the piston rod, wherein a clearance exists between the actuatable member and the piston rod, wherein the actuatable member is actuatable, and wherein the actuation of the actuatable member regulates flow of the hydraulic fluid between the vacant region and the second chamber through the first orifice and the clearance.

14. The suspension strut as claimed in claim 13, wherein the actuatable member is a needle that is rotatable, and wherein the suspension strut comprises a knob coupled to an end of the needle that is away from the cylinder, the knob being usable to rotate the needle.

15. A vehicle comprising: a body; a wheel; and a suspension strut coupling the body with the wheel, the suspension strut comprising: a cylinder filled with a hydraulic fluid; a piston disposed in the cylinder and dividing the cylinder into a first chamber and a second chamber, the piston having an opening to allow flow of the hydraulic fluid between the first chamber and the second chamber; a piston rod having a portion disposed in the first chamber and defining a vacant region in the first chamber between a piston rod wall and a cylinder wall, the piston rod being coupled to the piston to reciprocate along with the piston, wherein the piston rod is hollow and has a first orifice extending through the piston rod wall; and an actuatable member extending through a hollow interior of the piston rod, wherein a clearance exists between the actuatable member and the piston rod, wherein an actuation of the actuatable member regulates flow of the hydraulic fluid between the vacant region and the second chamber through the first orifice and the clearance.

16. The vehicle as claimed in claim 15, wherein the actuatable member is a needle that is rotatable, and wherein the vehicle comprises a motor coupled to the needle to rotate the needle.

17. A method for controlling damping force exerted by a suspension damper, the suspension damper having a cylinder with a hydraulic fluid and a piston disposed in the cylinder and dividing the cylinder into a first chamber and a second chamber, the piston having an opening defining a primary flow of the hydraulic fluid between the first chamber and the second chamber, a piston rod being coupled to the piston, the method comprising: providing a secondary flow of hydraulic fluid between the first chamber and the second chamber, the secondary flow being defined by a first orifice provided in the piston rod; and controlling the secondary flow based on actuation of an actuatable member configured in communication with the first orifice.