FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION STRUT OPENING ASSEMBLY
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India


INVENTOR
Mr Bonde Praful Liladhar, Mr Vivek Lakhera Mr Krishnan Shripathi, Mr Mayuresh Madhukar Deo
all Indian nationals of TATA MOTORS LIMITED
an Indian company having its registered office at
Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed


FIELD OF INVENTION
The present invention discloses a structure, which enables the assembly and disassembly of strut and shock absorber used in suspension in a vehicle. This is replaced to a hydraulic & pneumatic power assisted mechanism. Further more, this is purely a mechanical device and is manually operated to control the upward and downward movement of the actuator. Sufficient mechanical advantage is provided for the ease of the operator. Safety is one of the major criteria considered while designing the assembly.
BACKGROUND OF INVENTION
Strut opening is tedious and unsafe with existing assembly available, and therefore needs extra care and skill during operations. Most of the assemblies use hydraulic or pneumatic power assistance, which needs high level of skill. This is quite costly and has complex control system. Manual Strut opening assembly is a simplified version of the existing system available. This assembly is operated manually and no external power assistance is required. Available assembly are power assisted and works on the principal of displacement control, as the control provided on the assembly is only in terms of displacement and does not react to load. Excess loading may lead to an accident due to spring slippage or dislocation of strut. To avoid this kind of incidents the manual operated strut opening assembly is designed which is closed loop system. The close loop comparison between power assisted and manual operated strut opener is shown in Figure 7.
Most of the assembly are fixed to ground and are not movable, whereas during damper ride tuning and suspension component iterations for chassis tuning, struts are required to be assembled and reassembled on site. To meet these kinds of criteria it becomes
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difficult to have external power sources availability. Thus to suite these kind of requirements this fixture is designed with manual operation to work on site. The size and weight of the assembly is suitable enough for easy movement and transportation.
OBJECT OF INVENTION
The purpose of designing the assembly is safety and easy strut opening-assembly and removal mechanism. Basically this assembly is used for damping tuning exercise. During this exercise strut dampers need to be replaced frequently with other operations like changing of springs, bump stoppers and mounts etc. Strut needs to be opened and suspension tuning is done. Spring preloading on the strut is too high, it varies from 200-600 kgf. During assembly or disassembly of strut, it may lead to an accident because high preloading. . A closed system ensure safety and the manual operations make this safer. All the hydraulic / pneumatic assisted systems are based on displacement controls, this does not predict any load change or does not sound an alarm before accidents. These systems are open loop systems, which are not full proof for operators and need extra care during operations. It is desired to have the closed loop mechanism, which ensures the safety. Keeping this in mind the manual strut opening assembly is designed which is operated manually to ensure the safety of persons working. While working on the manual strut opener the operator will be able to sense the load, according to the load increase or decrease the operator ensures the proper fitment of strut grip or clamp. The effort required to perform the operation is reduced with the help of gear box and lever , which gives higher mechanical advantage. The variation in load is sensed by the operator visually by inspecting any spring slippage or deformation in the strut and accordingly takes the necessary action required.
The advantage of this system over hydraulic or pneumatic system is of the safety, ease of operations, mobile usage and cost. Cost of the assembly is negligible and does not
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require special tools or expertise to be made. Construction of the system is quite simple. Further, it is easy to understand the operation and repair procedures. This is not like other systems and controls, which make them quite complex and difficult to maintain. This system can be used at any location, and does not require any special surrounding like dust free environment. This assembly does not require any hydraulic, pneumatic or electrical power assistance . As there is no fluid or air used to operate, there is no kind of leakage to be checked during usage. Thus surrounding area is always clean and handling of the movement of the assembly becomes easy. This assembly does not require much maintenance and does not require additional care.
This system is easy to understand and operate due to its simplicity in design.
BRIEF DESCRIPTION OF INVENTION
This is a safe, precise and cost effective test assembly made for Strut opening and removal work. Assembly is having a box skeleton to it that it will be safe to operate even if it is not supported rigidly. A mechanical actuator is fitted on the base to load and unload the strut. Top plate profile is designed to constrain the movement of the top mount assembly.
A mechanical actuator is used for the assembly, said mechanical actuator has a gear box inside. This gear box provide mechanical advantage to reduce the effort required to put during operations by the operator. A lever is connected to the actuator, which has larger mechanical advantage for further ease. The mechanical actuator is simple and manual operated, does not need any power assistance like hydraulic, pneumatic or electric supply. An operator can easily perform the operation with out any difficulty as strut is constrained properly and effort need to be applied is very low compared to actual load coming on the strut. This mechanical actuator is fixed in a housing, and
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supported on the base plate with fasteners to constrain movements. The input torque is given by the lever. This input torque is amplified by the gear box provided in the actuator and the amplified force is given to the shaft through the upward movement. The fixture is mounted on the vertical shaft to accommodate the required up and down movement of the stroke for loading or reloading of the strut. Strut bottom end is fitted on the fixture with camber bolts fixed or round sleeve depending upon the type of suspension. The top mount is fixed on the top plate, so that the loading will be applied on the spring assembly to compress the spring and damper assembly. The required loading is done on the spring assembly, the top mount assembly will be free from load, and it will be safe to removed the strut top nut holding the bearing. As the top mount is fixed it the nut is free and no load will be applied during the removal, if there is any load remaining on the bearing and nut, it is required to load the strut further to achieve the free load condition of the nut and bearing. During operations ensure the top plate lever is fitted properly, and the top mount is constrained properly.
Accordingly, the present invention discloses a manually operated strut opening assembly comprising: a top plate member; a base member; a housing containing a mechanical actuator mounted on said base member; a plurality of assembly columns surrounding said strut are fixed at an angle of approximately 120° from each other to provisions provided on said top plate member for accessing strut fitment work during operations; and a fixture connecting the top of said mechanical actuator to strut bottom.
STATEMENT OF INVENTION
This invention relates to a manually operated strut opening assembly comprising; a top plate member; a base member; a housing containing a mechanical actuator mounted on said base member; a plurality of assembly columns surrounding said strut are fixed at an angle of approximately 120° from each other to provisions provided on
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said top plate member for accessing strut fitment work during operations; and a fixture connecting the top of said mechanical actuator to strut bottom.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 shows the schematic drawing of the strut opening assembly according to the
present invention.
Figure 2 shows manual strut opening assembly base
Figure 3 shows the top view of the top plate of the strut opening assembly according to
this invention.
Figure 4 shows the column location on the top plate;
Figure 5 shows the actuator fitted on the base of the strut opening assembly;
Figure 6a shows the fixture for a McPherson type strut for connecting the actuator top
and the bottom of the strut
Figure 6b shows the fixture for a rear shock absorber for connecting the actuator top
and the bottom of the strut;
Figure 7a shows the power assisted strut opening assembly with open loop as in the
prior art;
Figure 7b shows the manual operated strut opening assembly with closed loop.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the
same,
The manual operated strut opening assembly as illustrated in Fig 1, can be divided into three parts to facilitate easy understanding of the structure.
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The strut opening assembly of the present invention comprises a base (6) which is a rigid member on which the entire structure is made. The base (6) is rigid enough to support during strut loading and unloading and other operations during use. Fig 2 shows the basic design of the base (6). Base (6) has tapping (13) on it on which housing (4) containing actuator (7) is fitted. The fitment is done with a plurality of fasteners, such as bolts or Allen bolts, on which the housing (4) is fixed.
The housing (4) containing the mechanical actuator (7) is a six-sided box-like structure and is closed on all sides. The bottom surface of the housing structure (4) is assemblyid and is fitted to the base (6) and the mechanical actuator (7) with fasteners. The front side surface of the housing (4) comprises a hole (8) though which the actuator input shaft on which the lever (5) is connected is fitted. The top plate of the housing(4) has a hole through which the actuator shaft (3) is movably mounted, said actuator shaft (3) is configured to load and unload the strut.
Atleast three columns (2) are used for the assembly and are placed vertically at approximately 120 degree to each other for the sake of access of strut fitment work during operations. The length is calculated considering the strut length and travel for the passenger car vehicles so that all variant of strut can be accommodated. Fig 3 shows the the column arrangement for the columns. The columns (2) are fixed at an angle of 120° from each other to the provisions (10) provided on the top plate (1).
The top plate (1) is supported by at least three columns as mentioned in the preceding paragraph. The top plate (1) is open at one end for the strut top cup fitment. A strip (14) is hinged at one end and pinned on the other end covers the forth side of the plate this will constrain the strut top cup movement and will hold at the desired location. With these arrangement the strut top cup - bearing assembly is constrained in X, Y and Z direction.
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Mechanical actuator (7) used for this assembly does not require any power assistance and works on basic gear systems. Operator using the assembly is required to give the torque to lever (5) which is amplified and the force is applied to the strut though a fixture. The lever (5) is attached to the actuator (7). In this system for actuator (7) there is a two level mechanical advantage used for the sake of operators ease of operation. Mechanical actuator (7) is fixed on the bottom plate of the housing (4) with fasteners.
The connection between mechanical actuator (7) and the strut bottom is done with the help of a fixture (11a -Fixture for torsional stiffness measurement, lib - Fixture for conical stiffness measurement) which facilitates for McPherson type strut and/or the multi-link suspension type having shock absorber and a round sleeve at the bottom. The fixture (11a, lib) is designed to match the profile. For McPherson strut kind of suspension, strut is constrained by the camber bolts to restrict the lateral movement , where as for the shock absorber having round sleeve at the bottom is constrained with sleeve attached to the vertical hollow shaft with cut on the top to accommodate the shock absorber. These fixtures are designed to hold the bottom end of the strut movement in all the direction X, Y and Z directions.
The manual strut opening assembly is a closed structure, made specifically so that resultant will be enclosed in the skeleton which will ensure safety. As the resultant forces on the system are not there it does not need strong and rigid foundation to be available for use. Strut to be opened is surrounded by at least three columns (2). This will guide and ease the operations. Top plate (1) is designed in such a way that it will constrain strut top mount movement and the bottom of the strut, which rests on fixture (11a, lib) also constrains the movement of the bottom of the strut and ensures non-slippage of strut from the assembly during operations
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Fixture is made to basically meet four criteria mentioned below.
a) Raise and lower height to accommodate the fitment of strut and actor head.
b) Get the sufficient travel if travel is not sufficient for loading or unlading the strut.
c) Constrain the lateral movements of strut during operations
d) Transmit the load from actuator to strut.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as tiaimed ox the equVvaieTits thereof.
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WE CLAIM
1. A manually operated strut opening assembly comprising:
a top plate member;
a base member;
a housing containing a mechanical actuator mounted on said base member;
a plurality of assembly columns surrounding said strut are fixed at an angle of approximately 120° from each other to provisions provided on said top plate member for accessing strut fitment work during operations; and
a fixture connecting the top of said mechanical actuator to strut bottom.
2. The assembly as claimed in claim 1, wherein said top plate member is open at one end for the strut top cup fitment and comprises apertures for fitment of said plurality of columns.
3. The assembly as claimed in claim 1, wherein said base member comprises a plurality of taps on which said housing containing said mechanical actuator is fitted with a plurality of fasteners.
4. The assembly as claimed in claim 1, wherein said housing is a six-sided closed box-like member.
5. The assembly as claimed in claim 4, wherein bottom surface of said housing is fitted to said base member.
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6. The assembly as claimed in claim 4, wherein front side surface of said housing comprises a hole though which input shaft of said mechanical actuator having a lever is fitted.
7. The assembly as claimed in claim 4, wherein top surface of said housing has an aperture through which actuator shaft of said mechanical actuator is movably mounted, said actuator shaft is configured to load and unload the strut.
8. The assembly as claimed in claim 1, wherein length of said plurality of columns is calculated considering the strut length and travel for passenger car vehicles so that all variant of strut can be accommodated.
9. The assembly as claimed in claim 2, wherein a strip hinged at one end and pinned on the other end covers one side of said top plate to constrain and hold the strut top cup movement at a desired location.
10. The assembly as claimed in claim 4, wherein Mechanical actuator (7) is fixed on the bottom surface of the housing.
11. The assembly as claimed in claim 1, wherein said fixture facilitates McPherson type strut whereby said strut is constrained by fasteners, preferably camber bolts, to restrict lateral movement.
12. The assembly as claimed in claim 1, wherein said fixture facilitates multi-link suspension type having shock absorber and a round sleeve at the bottom whereby said strut is constrained with sleeve attached to a vertical hollow shaft with cut on the top to accommodate said shock absorber.
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13. A manually operated strut opening assembly as hereinabove described with reference to the accompanying drawings.