FIELD OF INVENTION

The present invention relates to suspension system for a vehicle and more particularly, to a semi-active
suspension apparatus and mounting arrangement thereof.

BACKGROUND OF THE INVENTION

This invention relates to an actuation mechanism for a hydraulic damper and more particularly hydraulic dampers of the type comprising a cylinder containing therein hydraulic fluid, a piston working in the cylinder and dividing the interior thereof into two chambers, a piston rod secured to the piston and extending to the outside of the damper, and a damping force adjusting device operable from the outside of the damper to change or adjust the damping force of the damper.

In one of the prior art hydraulic dampers of this type, the damping force adjusting mechanism is mounted inside the damper housing. The damper works satisfactorily, however, the construction of the damper is complicated, and due to its size the damper cannot be installed in a restricted space. Further, due to size constraints the power of actuator i.e. motor is also restricted.

SUMMARY

An object of the present invention is to provide a suspension apparatus eliminating the shortcomings described above. This is achieved by providing a hydraulic damper of above-mentioned type comprises a hollow piston rod having a rod member extending co-axially therethrough, and an orifice connected to the inner end of the rod member. By actuating the rod member from the outside, the damping force is adjusted by changing the effective area of the orifice connecting the both chambers. An actuating linear actuating member is installed on a frame member coaxially with the damper, an actuating rod operatively coupling the output shaft of the actuating member and the rod member is attached to the said output shaft pivotally in manner so that the shaft can pivot in a two dimensional plane along with the hydraulic damper transmitting the axial force. The range of pivotal movement is provided based on the damper design and arrangement. The present invention includes a body side mounting assembly for securing an end of hydraulic damper to the body of the vehicle at the same time allowing the rod member to pass through the mounting assembly to the output shaft of the linear actuating member that is secured fixedly to the body of the vehicle.

This invention removes the restriction on size and specification of the actuating member without affecting the dimensions and design of the damper, as it is placed on the vehicle body outside the hydraulic damper housing. Preferably, the actuating member is an electromagnetic actuator compatible with the control unit design.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1A and 1B depicts a three-wheeled vehicle and frame structure thereof respectively, embodying the present invention;

FIG. 2 is an enlarged cross-section view of the semi-active suspension assembly as mounted on the vehicle;

FIG. 3 is a cross-sectional view, of the semi-active suspension assembly from the rear side of the vehicle;

FIG. 4 is a prospective view showing a fork-shaped bracket used in amounting assembly as per an embodiment of the invention;

FIG. 5 is a prospective view showing an inverted U-shaped bracket used in a mounting assembly as per an embodiment of the invention;

FIG. 6 is a prospective view of the motor mounting plate used in a mounting assembly as per an embodiment of the invention.

FIG. 7 is a cross-sectional view of the mounting arrangement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 depicts frame structure of a three-wheeled vehicle 01 defining an operator's cabin 06 and a passenger's cabin 05. Body structure 02 on the rear side has a wheel support structure 03 pivotally secured to the body structure 02 for supporting a wheel. Preferably, at least a portion of the wheel support structure 03 is connected to the body structure 02 through a shock absorber apparatus 04 of the present invention.

The shock absorber apparatus 04 comprises of a damper 07, a spring element 08 and an electromagnetic actuator 09. The said damper 07 is a hydraulic damper having a variable damping coefficient, comprising a cylinder 07A having opposite closed ends termed as a reservoir end and a piston end for containing hydraulic fluid. A piston 12 having two sides, at least an orifice 13 and plurality of one-way valves therethrough, each of the said one-way valves is operational either at compression or at rebound of the shock absorber. Said piston 12 is being positioned within the interior of said cylinder 07A and being slidable in the direction of the longitudinal axis of said cylinder 07A, dividing the interior of said cylinder 07A into a first chamber 10 and a second chamber 11, a hollow piston rod 12A having an axial bore throughout its axial length, is secured to the piston 12 by first one of the said piston sides. The piston rod extends through the second oil chamber 11 to the outside of the cylinder 07A. The said first chamber 10 and second chamber 11 communicates through the said orifice 13, a metering pin 14 is positioned slidably, with one end adapted for projection into interior of said orifice 13 for controlling communication between said two chambers 10 and 11. An adjusting member has a stem portion 15 having lower end connected to the metering pin 14. The stem portion 15 sealably extends through the axial bore and the upper end projects out of the piston rod 12A.

In an embodiment, the upper end of the stem is connected to the output shaft 16 of a linear stepper motor 09 to slide the metering pin 14 on the bases of the control signal. Further, said metering pin 14 being tapered longitudinally of decreasing diameter towards, the end for projection into interior of said orifice, whereby on initial insertion the metering is minimum and gradually increases along the increasing diameter of metering pin. Thus, controlling the resistance to the passage of fluid from said first chamber 10 to said second chamber 11 consequently controlling the damping coefficient.

In an embodiment of the present invention/the said damper 07 along with the shock absorber (spring 08) is pivotally secured between a mount portion 02A formed at a part of body 02 of the vehicle 01 and wheel support structure 03.

The piston end of the damper 07 is secured through a body side mounting assembly to the said mount position 02A and the reservoir end of the damper 07 is secured through a wheel side mounting assembly to the wheel support structure 03. The body side mounting assembly includes a fork shaped bracket 19 having two side members 19A and 19B parallel to each other and united at one end forming a forked structure The fork shaped bracket 19 is secured to the damper housing through the united end and having a through hole 19D along the axis to allow the extended stem 15 to pass through. The forked sides 19A and 19B have holes 19C for bolting. Further, an inverted U shaped bracket 20 having two sides projecting downwards from a horizontal surface. The sides projecting downwards and forming inverted U structure have holes 20B corresponding to holes 19C in the forked shaped bracket. The inverted U shaped bracket 20 is secured to the mount portion 02A suitably through the said horizontal surface. The forked sides 19A and 19B are interposed inside the sides projecting downwards and forming U shape and are secured through the corresponding holes using nut and bolt pair 21 and 22, an axial through hole is provided through the U shape bracket 20 and the mount portion 02A so as to receive the output shaft 16 of the linear stepper motor 09 that is fixedly secured over the mount portion 02A using a mount plate 17 to enable the axis of the output shaft 16 to coincide with the axis of damper 07. The output shaft 16 of the stepper motor 09 is connected to the upper portion of the extended stem through a pinhole joint wherein the pin 23 is coaxial with the axis' of rotation of the fork shaped bracket 19 and the inverted u-shaped bracket 20. The through holes provided in the fork shaped bracket 19, U shaped bracket 20 and mount portion 02A are coaxial with the damper. Further, a two point contact is provided for the damper to swing pivotally during operation and the said pin hole joint provided between the output shaft of motor 16 and the extended stem 15 transfers the axial force during actuation and at the same time the extended stem 15 has a limited freedom to align with the axis of the damper during operation. In the present embodiment the limited freedom to align with the axis of the damper during operation is restricted to 5 to 10 degrees.

Thus, as the electromagnetic actuator that is a linear stepper motor in this case is fixed on the body of the vehicle, which enables the motor to be of higher power and even larger dimensions without affecting the design of the damper.

It will be noted that the invention is not limited to the embodiments illustrated and described, and various changes or modifications within the gist of the invention can easily be applied by those skilled in the art. For example, a motor and an external linear actuator may substitute the linear stepper motor.

We Claim:

1. A suspension apparatus for a vehicle configured to generate a variable damping force with respect to relative movement of a wheel and body of the vehicle comprising:

a wheel-side mounting unit pivotally coupled to a wheel-holding portion for holding the wheel of the vehicle;

a body-side mounting unit which is coupled to a mount portion formed at a part of a body of the vehicle;

a hydraulic damper having a reservoir end and a piston end being disposed between the said wheel-side mounting unit and said mount portion, pivotally supported by the said wheel-side mounting unit at reservoir end and body side mounting unit at piston end; said hydraulic damper comprising a housing which stores a working fluid; a piston which divides an interior of the housing into two fluid chambers; a linearly actuable flow-resistance imparting mechanism which imparts a resistance to a flow of the working fluid between the two fluid chambers associated with a movement of the piston;

an electromagnetic actuator having an output shaft, fixedly mounted over the said mount portion, so as to be coaxial with the hydraulic damper wherein, the said shaft passes through said mount portion; an actuation rod operatively coupling the said output shaft to said linearly actuable flow-resistance imparting mechanism, wherein the actuation rod is connected to the output shaft by a joining means adapted to permit restricted range of pivotal movement of the actuation rod in a two dimensional plane along with the axis of hydraulic damper.

2. The suspension apparatus according to claim 1, wherein the electromagnetic actuator is fixedly mounted over the said mounting portion through a bracket adapted to align the output shaft of the electromagnetic actuator coaxially with the hydraulic damper.

3. The suspension apparatus according to claim 1, wherein the said joining means is a pinhole joint.

4. The suspension apparatus according to claim 1, wherein the body-side mounting unit comprises a bottom member and a top member having through hole along the axis of hydraulic damper adapted to slidably accommodate the actuation rod.

5. The suspension apparatus according to claim 4, wherein the bottom member is fork shaped and the upper member is inverted U-shaped adapted such that the forked ends are interposed and secured inside the inverted U-shape.