DESC:FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
&
THE PATENTS (AMENDMENT) RULES, 2006
COMPLETE SPECIFICATION
[See Section 10; rule 13]
“TENSIONER ASSEMBLY FOR CYLINDER BORE OF A COMPACT ENGINE”
ADVIK HI-TECH PVT LTD, a company of Gat No. 357/99 Chakan Talegaon Road, Village Kharabwadi, Chakan Tal. Khed, Pune, Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed:
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FIELD OF INVENTION
[0001] The present invention relates to tensioner assemblies for cylinder bores of compact engines. More specifically, the present invention relates to a tensioner assembly for cylinder bore of a compact engine having reduced neck diameter.
BACKGROUND OF THE INVENTION 5
[0002] In recent years, engines of straddle-type vehicles with less aerodynamic volume displacement and smaller size have been developed which require dimensions of tensioners for their cylinder bores to be reduced. The neck of conventional tensioners is inserted in the cylinder bore with support of other components, which hinders the capability of the neck diameter of the tensioners to 10 be reduced.
[0003] A conventional tensioner consists of a body, a screw, a nut, a retainer, a bearing, a stopper, a cap, a spring, and a circlip. The tensioner body has cylindrical portions extending on both sides from a flange or towards the cylinder side. The spring has its one end placed in a slit of the screw and other end placed in a slit 15 provided in the body. The screw is engaged with the nut via threads therein. The stopper is used to provide rotary motion to the screw which forces the spring to rotate as well. Upon removal of the stopper from the screw, the stored elastic energy in the spring rotates the screw. The retainer, commonly made up of sheet metal is placed on the body of the tensioner and acts as a guide for motion of the nut. Since 20 the screw is engaged with the nut via threads, rotary motion of the screw is converted into linear motion of the nut as the bearing prevents the nut from rotating.
[0004] In conventional tensioners, the retainer is required to be mounted on the cylindrical shape of the body. To compensate for the same, shape of the retainer is selected as a tube like component due to which neck diameter of the tensioner which 25 is required to be inserted into the cylinder bore increases and is unalterable considering the retainer diameter. Also, the retainer of such conventional tensioner
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assemblies accommodates other components of the tensioners, and is either fixed on the body and/or is shaped as a tube shaped component fixed on the body. To this effect, as illustrated in Figs. 1A, 1B, and 1C, outlined portions having large diameter are inserted into cylinder bores as other parts are also required to be placed in the cylinder bores. 5
[0005] There is therefore a need in the art to provide a compact tensioner assembly capable of addressing the deficiencies associated with the conventional tensioner assemblies.
OBJECTS OF THE INVENTION 10
[0006] An object of the present invention is to provide a tensioner assembly for insertion into an opening of a cylinder bore of a compact engine.
[0007] Another object of the present invention is to reduce neck diameter of the tensioner assembly.
[0008] Another object of the present invention is to reduce the dimension of 15 the opening of the cylinder bore in which the neck of the tensioner assembly is inserted.
[0009] Another object of the present invention is to provide a compact tensioner assembly.
[00010] Still another object of the present invention is to provide a tensioner 20 assembly capable of avoiding leakage of oil from mountings of the engine.
SUMMARY OF THE INVENTION
[00011] The present invention relates to a tensioner assembly for cylinder bore of a compact engine. The tensioner assembly includes a flat plate (also referred to 25
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as “plate” hereinafter) coupled with a body of the tensioner assembly to form an enclosure, a nut passing through a guide portion of the plate, and a screw operatively coupled with the nut. The screw is coupled with a torsional spring to enable axial movement of the nut through the guide portion of the plate by rotation of the screw and decompression of the torsional spring from a compressed state. 5
[00012] According to an embodiment of the present invention, diameter of the torsional spring is greater than diameter of the screw such that the torsional spring encircles the screw.
[00013] According to an embodiment of the present invention, the plate comprises a locking portion adapted to restrict axial movement of the nut through 10 the guide portion of the plate after a pre-defined extent of rotation of the nut.
[00014] According to an embodiment of the present invention, a gasket is arranged between the plate and the body to prevent leakage of fluid when the tensioner assembly is fitted onto any of an opening of the cylinder bore and a mounting portion of the compact engine. 15
[00015] According to an embodiment of the present invention, the plate has a flatness of up to 0.2 mm and surface roughness ranging from Ra 0.8 to Ra 3.2.
[00016] According to an embodiment of the present invention, the tensioner assembly includes a spacer arranged between the body and the screw.
[00017] According to an embodiment of the present invention, the tensioner 20 assembly includes a plug disposed at one end of the torsional spring for supporting rotation of the screw and preventing contact of the screw with the body of the tensioner assembly.
[00018] According to an embodiment of the present invention, the nut has a specific neck diameter which is to be inserted into any of an opening of the cylinder 25 bore and a mounting portion of the compact engine. The nut has a diameter of 10.5 mm.
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[00019] According to an embodiment of the present invention, an open end of the nut is fitted with a cap having a diameter of upto 12.5 mm.
[00020] According to an embodiment of the present invention, the tensioner assembly includes a stopper to enable rotation of the screw and a seal plug to prevent leakage of fluid when the tensioner assembly is fitted onto any of the 5 opening of the cylinder bore and the mounting portion of the compact engine.
[00021] According to an embodiment of the present invention, diameter of the nut is equal to the neck diameter of the tensioner assembly having a reduced dimension which can be effectively inserted into any of the opening of the cylinder bore and the mounting portion of the compact engine. 10
BRIEF DESCRIPTION OF THE DRAWINGS
[00022] The accompanying drawings constitute a part of the description and are used to provide further understanding of the present invention. Such accompanying drawings illustrate the embodiments of the present invention which are used to 15 describe the principles of the present invention together with the description.
[00023] Figs. 1A through 1C illustrate front perspective views of conventional tensioners to be fitted with engine mountings having large neck diameters;
[00024] Fig. 2 illustrates an exploded view of the tensioner assembly, in accordance with an embodiment of the present invention; 20
[00025] Figs. 3A and 3B illustrate cross-sectional views of the tensioner assembly, in accordance with an embodiment of the present invention;
[00026] Figs. 4A through 4C illustrate perspective views of the tensioner assembly, in accordance with an embodiment of the present invention;
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[00027] Figs. 5A through 5C illustrate perspective views of a flat plate of the tensioner assembly, in accordance with an embodiment of the present invention; and
[00028] Fig. 6 illustrates an exemplary representation of a performance chart of the tensioner assembly, in accordance with an embodiment of the present invention. 5
DETAILED DESCRIPTION OF THE INVENTION
[00029] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of 10 “in” includes “in” and “on” unless the context clearly dictates otherwise.
[00030] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[00031] Exemplary embodiments will now be described more fully hereinafter 15 with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those of ordinary skill in the art. 20 Moreover, all statements herein reciting embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). 25
[00032] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition
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persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[00033] In some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some 5 embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. 10 The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[00034] According to an embodiment of the present invention, since tubular shaped retainers, incorporated in conventional tensioners, restrict reduction of their 15 neck diameters, tensioner assembly of the present invention prevents usage of the tubular shaped retainers, thereby effectively reducing its neck diameter.
[00035] An aspect of the present invention pertains to a tensioner assembly for cylinder bore of a compact engine, the tensioner assembly including a plate coupled with a body of the tensioner assembly to form an enclosure, a nut passing through 20 a guide portion of the plate, and a screw operatively coupled with the nut. The screw is coupled with a torsional spring to enable axial movement of the nut through the guide portion of the plate by rotation of the screw and decompression of the torsional spring from a compressed state. The plate may include a locking portion for restricting axial movement of the nut after a pre-defined extent of rotation of the 25 nut. Diameter of the nut is equal to neck diameter of the tensioner assembly having a reduced dimension which can be effectively inserted into any of an opening of the cylinder bore and a mounting portion of the compact engine.
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[00036] Fig. 2 illustrates an exploded view of the tensioner assembly, in accordance with an embodiment of the present invention. The tensioner assembly includes a screw (106), a plunger/nut (108), a body (102), a torsional spring (104), a flat plate (116), a pin, a circlip, a cap (120), a gasket (118) and a stopper (112).
[00037] According to an embodiment of the present invention, the plate (116) is 5 provided with a locking portion and a guiding portion to enable restrictive movement of the nut (108).
[00038] According to an embodiment of the present invention, the plate (116) is fitted with the body (102) of the tensioner assembly with the help of fasteners (124), such as, screws and bolts, to form an enclosure accommodating the components of 10 the tensioner assembly.
[00039] According to an embodiment of the present invention, the plate (116) is fixed with the body (102) of the tensioner assembly and the gasket (118) is provided to prevent leakage so that all components of the tensioner assembly remain intact. The plate (116) is fitted over the opening of the cylinder bore and/or a mounting of 15 the engine, and has a flatness of up to 0.2 mm and surface roughness in the range of Ra 0.8 to Ra 3.2.
[00040] According to an embodiment of the present invention, the screw (106) and the nut (108) are operatively coupled with each other, and the torsional spring (104) is fitted with the screw (106) such that rotation of the screw (106) and the nut 20 (108) is effected due to decompression of the torsional spring (104) from its compressed state. As clearly illustrated in Figs. 3A and 3B, diameter of the torsional spring (104) is greater than diameter of the screw (106) such that the torsional spring (104) encircles the screw (106).
[00041] According to an embodiment of the present invention, the flat plate 25 (116) is structured with the guiding portion for enabling axial movement of the nut (108), and the locking portion for arresting movement/displacement of the nut (108) after a pre-defined extent of rotation of the nut (108).
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[00042] According to an embodiment of the present invention, the tensioner assembly avoids the use of tubular shaped retainer, rather incorporates the nut (108) which is inserted in the opening of the cylinder bore. Therefore, diameter of the nut (108) is equal to the neck diameter of the tensioner assembly having a reduced dimension which can be effectively inserted into the opening of the cylinder bore. 5 To this effect, neck size of the tensioner assembly and dimensions of the opening of the cylinder block into which the tensioner assembly is required to be inserted are drastically reduced.
[00043] According to an embodiment of the present invention, the tensioner assembly includes a spacer (110) inserted in between the body (102) and the screw 10 (106), as illustrated in Fig. 2. The spacer (110) provides a passage from the gasket (118), the flat plate (116), and the nut (108) for their insertion into the body (102) while at the same time preventing metal-to-metal contact with components of the tensioner assembly, thereby reducing wear and tear between components of the tensioner assembly. 15
[00044] According to an embodiment of the present invention, the tensioner assembly includes a plug (122), as shown in Fig. 2. The plug (122) is disposed at one end of the torsional spring (104) for supporting rotation of the screw (106) while preventing contact of the screw (106) with the body (102) of the tensioner assembly. 20
[00045] Figs. 4A through 4C illustrate different perspective views of the tensioner assembly. An open end of the nut (108), inserted within the opening of the cylinder bore or any mounting of the engine, is provided with the cap (120) made up of a material having high thermal resistance and improved sealing properties for fitment of the open end of the nut (108) with the opening of the 25 cylinder bore or the mounting of the engine. Also, as clearly shown in Figs. 4A through 4C, the tensioner assembly may include the stopper (112) and a seal plug (114) to prevent leakage of fluid when the tensioner assembly is fitted onto the cylinder bore or any other mounting of the engine.
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[00046] According to an embodiment of the present invention, the neck diameter of the nut (108) is about 10.5 mm. The nut (108) is present in the form of a hollow tube having open ends. An open end of the nut (108) is covered by the cap (120) to close an opening of the nut (108). The cap (120) has a diameter of upto 12.5 mm. In operation, the cap (120) remains in contact with the opening of the 5 cylinder bore or the mounting portion of the engine, and transfers the forces generated by the tensioner assembly to the cylinder bore or the mounting portion of the engine. In certain implementations, where the tensioner assembly is installed with the mounting portion of the engine, the cap (120) touches a chain guide of the engine directly, and transmits the forces generated by the tensioner assembly 10 directly to the chain guide of the engine.
[00047] Figs. 5A and 5B illustrate front and rear perspective views of the flat plate (116), and Fig. 5C illustrate a top view of the flat plate (116) in accordance with an embodiment of the present invention. As shown, the flat plate (116) has a small opening (502) forming a passage for axial movement of the nut (108), and a 15 guide portion (504) guiding movement of the nut (108). The flat plate (116) also has a plurality of openings (506) for securing the flat plate (116) with the body (102) of the tensioner assembly. The plurality of openings (506) may have threaded portions to allow the fasteners (124) to securely lock the flat plate (116) with the body (102). The gasket (118) may be disposed in between the flat plate (116) and 20 the body (102) to prevent leakage of fluid when the tensioner assembly is fitted onto the opening of the cylinder bore or the mounting portion of the compact engine.
[00048] According to an embodiment of the present invention, the opening (502) of the flat plate (116) may have a plurality of grooves (locking portion) which restricts axial movement of the nut (108) through the guide portion (504) after a 25 pre-defined extent of rotation of the nut (108) due to rotation of the screw (106) and decompression of the torsional spring (104) from its compressed state.
[00049] According to an embodiment of the present invention, various tests as recommended by Original Equipment Manufacturers (OEMs) were conducted to
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assess performance and reliability of the tensioner assembly, and the test results were within acceptable limits. The tests included vehicle fitment test, performance test, impact durability test, leak test, salt spray test, fatigue test, and spring endurance test. Fig. 6 shows a result of the performance test in the form of a performance chart. The performance chart depicts load values of the tensioner 5 assembly at different strike length (displacement) of the tensioner assembly. It could be observed from the performance chart that the load decreases gradually with an increase in stroke length. Further, the load plummets for tensioner assembly having stroke lengths equal to or greater than 30 mm. In one implementation, the tensioner assembly may have a minimum stroke length of 18 mm with a wound 10 length of 12.5 mm. Also, no air leakage was observed during the leak test when the tensioner assembly was tested under an air pressure of 0.5 bar to 2 bar for more than 5 seconds.
[00050] In the above detailed description, reference is made to the accompanying drawings that form a part thereof, and illustrate the best mode 15 presently contemplated for carrying out the invention. However, such description should not be considered as any limitation of scope of the present invention. The structure thus conceived in the present description is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. 20
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We Claim:
1. A tensioner assembly for a cylinder bore of a compact engine, the tensioner assembly comprising:
a flat plate (116) coupled with a body (102) of the tensioner assembly to form an enclosure; 5
a nut (108) passing through a guide portion (504) of the flat plate (116); and
a screw (106) operatively coupled with the nut (108) and a torsional spring (104) to enable axial movement of the nut (108) through the guide portion (504) of the flat plate (116) by rotation of the screw (106) and decompression of the torsional spring (104) from a compressed state. 10
2. The tensioner assembly as claimed in claim 1, wherein a diameter of the torsional spring (104) is greater than a diameter of the screw (106).
3. The tensioner assembly as claimed in claim 1, wherein the flat plate (116) comprises a locking portion adapted to restrict axial movement of the nut (108) through the guide portion of the flat plate (116) after a pre-defined rotation of the 15 nut (108).
4. The tensioner assembly as claimed in claim 1, further comprising a gasket (118) arranged between the flat plate (116) and the body (102) to prevent leakage of fluid when the tensioner assembly is fitted onto any of an opening of the cylinder bore and a mounting portion of the compact engine. 20
5. The tensioner assembly as claimed in claim 1, wherein the flat plate (116) has a flatness of up to 0.2 mm and surface roughness ranging from Ra 0.8 to Ra 3.2.
6. The tensioner assembly as claimed in claim 1, further comprising a spacer (110) arranged between the body (102) and the screw (106).
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7. The tensioner assembly as claimed in claim 1, further comprising a plug (122) disposed at one end of the torsional spring (104) for supporting rotation of the screw (106) and preventing contact of the screw (106) with the body (102) of the tensioner assembly.
8. The tensioner assembly as claimed in claim 1, wherein the nut (108) has a 5 neck diameter of 10.5 mm for getting inserted into any of the opening of the cylinder bore and the mounting portion of the compact engine.
9. The tensioner assembly as claimed in claim 8, wherein an open end of the nut (108) is covered with a cap (120).
10. The tensioner assembly as claimed in claim 1, further comprising a stopper 10 (112) to enable rotation of the screw (106) and a seal plug (114) to prevent leakage of fluid when the tensioner assembly is fitted onto any of the opening of the cylinder bore and the mounting portion of the compact engine.
Dated this 05th day of June, 2020
(JAYANTA PAL)
PATENT AGENT NO: IN/PA-172
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT(S)
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ABSTRACT
TENSIONER ASSEMBLY FOR CYLINDER BORE OF A COMPACT ENGINE
A tensioner assembly for cylinder bore of a compact engine having reduced neck diameter is disclosed. The tensioner assembly comprises a plate (116) fitted with a body (102) of the tensioner assembly with the help of fasteners (124) to form an enclosure accommodating the components of the tensioner assembly. A gasket (118) is provided to prevent leakage so that all components of the tensioner assembly are intact in assembly. A screw (106) is operatively coupled with the nut (108), and a torsional spring (104) is fitted with the screw (106) such that rotation of the screw (106) and the nut (108) is effected due to decompression of the torsional spring (104) from its compressed state. Diameter of the nut (108) is the neck diameter of the tensioner assembly having a reduced dimension which can be effectively inserted into the opening of the cylinder bore.
Fig. 2
Fig. 1A
(PRIOR ART)
Fig. 1B
(PRIOR ART)
Fig. 1C
(PRIOR ART)
ADVIK HI-TECH PVT LTD,
APPLICATION NO: 201921022437 SHEET 1 OF 6
JAYANTA PAL
PATENT AGENT NO: IN/PA-172
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT(S)
Fig. 2
102
104
106
110
114
112
122
118
120
108
116
124
ADVIK HI-TECH PVT LTD,
APPLICATION NO: 201921022437 SHEET 2 OF 6
JAYANTA PAL
PATENT AGENT NO: IN/PA-172
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT(S)
Fig. 3A Fig. 3B
120
108
102
104
106
112
114
120
108
102
104
106
112
114
ADVIK HI-TECH PVT LTD,
APPLICATION NO: 201921022437 SHEET 3 OF 6
JAYANTA PAL
PATENT AGENT NO: IN/PA-172
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT(S)
Fig. 4B
Fig. 4C
Fig. 4A
102
114
112
116
108 120
120
116
114
112
102
116
ADVIK HI-TECH PVT LTD,
APPLICATION NO: 201921022437 SHEET 4 OF 6
JAYANTA PAL
PATENT AGENT NO: IN/PA-172
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT(S)
Fig. 5A Fig. 5B
Fig. 5C
116
116
116
502
504
506
506
ADVIK HI-TECH PVT LTD,
APPLICATION NO: 201921022437 SHEET 5 OF 6
JAYANTA PAL
PATENT AGENT NO: IN/PA-172
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT(S)
Fig. 6
ADVIK HI-TECH PVT LTD,
APPLICATION NO: 201921022437 SHEET 6 OF 6
JAYANTA PAL
PATENT AGENT NO: IN/PA-172
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT(S) ,CLAIMS:We Claim:
1. A tensioner assembly for a cylinder bore of a compact engine, the tensioner assembly comprising:
a flat plate (116) coupled with a body (102) of the tensioner assembly to form an enclosure; 5
a nut (108) passing through a guide portion (504) of the flat plate (116); and
a screw (106) operatively coupled with the nut (108) and a torsional spring (104) to enable axial movement of the nut (108) through the guide portion (504) of the flat plate (116) by rotation of the screw (106) and decompression of the torsional spring (104) from a compressed state. 10
2. The tensioner assembly as claimed in claim 1, wherein a diameter of the torsional spring (104) is greater than a diameter of the screw (106).
3. The tensioner assembly as claimed in claim 1, wherein the flat plate (116) comprises a locking portion adapted to restrict axial movement of the nut (108) through the guide portion of the flat plate (116) after a pre-defined rotation of the 15 nut (108).
4. The tensioner assembly as claimed in claim 1, further comprising a gasket (118) arranged between the flat plate (116) and the body (102) to prevent leakage of fluid when the tensioner assembly is fitted onto any of an opening of the cylinder bore and a mounting portion of the compact engine. 20
5. The tensioner assembly as claimed in claim 1, wherein the flat plate (116) has a flatness of up to 0.2 mm and surface roughness ranging from Ra 0.8 to Ra 3.2.
6. The tensioner assembly as claimed in claim 1, further comprising a spacer (110) arranged between the body (102) and the screw (106).
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7. The tensioner assembly as claimed in claim 1, further comprising a plug (122) disposed at one end of the torsional spring (104) for supporting rotation of the screw (106) and preventing contact of the screw (106) with the body (102) of the tensioner assembly.
8. The tensioner assembly as claimed in claim 1, wherein the nut (108) has a 5 neck diameter of 10.5 mm for getting inserted into any of the opening of the cylinder bore and the mounting portion of the compact engine.
9. The tensioner assembly as claimed in claim 8, wherein an open end of the nut (108) is covered with a cap (120).
10. The tensioner assembly as claimed in claim 1, further comprising a stopper 10 (112) to enable rotation of the screw (106) and a seal plug (114) to prevent leakage of fluid when the tensioner assembly is fitted onto any of the opening of the cylinder bore and the mounting portion of the compact engine.