Court Cranks the Clock Back on Opposed Crankshaft Patent Refusal

In the case of Pinnacle Engines Inc. vs. The Assistant Controller of Patents & Designs, the Madras High Court addressed an appeal challenging the rejection of a patent application relating to internal combustion engines (ICEs) by the Assistant Controller of Patents & Designs. The appellants, Pinnacle Engines Inc. and TVS Motor Company Limited sought a patent for an invention titled “OPPOSED PISTON ENGINE WITH NON-COLLINEAR AXES OF TRANSLATION,” which pertains to internal combustion engines with an innovative configuration of opposed pistons.

The patent application, filed on October 8, 2012, claimed an invention involving opposed pistons that reciprocate along non-collinear axes, creating a larger combustion chamber area and reducing engine width, friction, and vibration. The Assistant Controller raised inventive step objections to the grant of patent based on 5 prior art references (D1 to D5) in his examination report. In response, the Appellants amended the patent claims and was later called for a hearing based on the same objections. Following the hearing, the Appellants filed written submissions with further claim amendments. Not satisfied, the Assistant Controller rejected the application primarily based on a lack of inventive step in the context of 3 prior art references.

On appeal, the Appellants argued that prior art documents cited did not disclose key features of their invention, such as the crank offset and the opposite rotation of crankshafts. The Appellants pointed out that these features reduced engine friction and vibration, solving issues associated with conventional opposed piston engines. Additionally, it emphasized that prior art references cited did not teach or suggest the inventive step claimed by the appellants.

Upon examining the prior art references, the court noted that they did not disclose or suggest the critical inventive features of the crank offset and the opposite rotation of crankshafts that formed part of the Appellants’ claimed invention. In paras 11 to 19 of the judgment, the court emphasized that the Assistant Controller’s decision lacked a detailed analysis of these features. The court found that the order of the Assistant Controller merely listed elements of the claimed invention without discussing the specific inventive steps that distinguished it from the prior art.

Furthermore, the court observed that the inventive features were added in the amended claims after the oral hearing, specifically addressing the crank offset and opposite crankshaft rotation. These features were included in the complete specification as an option, making the amendments permissible under Section 59 of the Patents Act. The court pointed out that these inventive features were not considered by the Assistant Controller, probably because the amendments were made at the written submissions stage.

Finally, the court concluded that the Assistant Controller’s order was effectively unreasoned and could not be sustained. It remanded the application for reconsideration on the limited aspect of the inventive features, specifically the crank offsets and opposite crankshaft rotation. The court directed that the reassessment be conducted by a different officer within three months, given the twelve-year duration that had lapsed since the application was filed.

  Court’s Analysis of the Assistant Controller’s Order: Relevant Paragraphs

“Discussion, analysis and conclusions

  1. In order to examine whether the claimed invention involves an inventive step, it is necessary to refer to the sequence of material events relating to the prosecution of the patent application. The appellants filed claims 1-24 with the patent application. Out of these, I set out the original independent claims 1 and 13 and material dependent claims 6, 7, 18 and 19, which were as under:

 “1. An opposed piston internal combustion engine comprising: a first piston reciprocating along a first axis of translation within a first cylinder bore in an engine block, the first piston reciprocating between a first top dead center position and a first bottom dead center position, the first piston comprising a first piston crown ;

 a first crankshaft configured to be rotated under influence of the reciprocating of the first piston, the first crankshaft disposed close to the first bottom dead center position than to the first top dead center position;

 a second piston reciprocating along a second axis of translation within a second cylinder bore in the engine block, the second piston reciprocating between a second top dead center position and a second bottom dead center position, the second axis of transaction being inclined at an included angle relative to the first axis of transaction, the included angle having a vertex that is closer to the first and the second top dead center positions than to the first and the second bottom dead center positions, the second piston comprising a second piston crown, the second piston crown and the first piston crown at least partially defining a combustion chamber within the opposed piston internal combustion;

and a second crankshaft configured to be rotated under influence of the reciprocating of the second piston, the second crankshaft disposed closer to the second bottom dead center position than to the second top dead center position.

  1. An opposed piston internal combustion engine as in any of claims 1 to 5, further comprising: a first sleeve valve associated with the first piston to control opening and closing of an inlet port for allowing delivery of at least one of fuel and air to the combustion chamber, the first sleeve valve at least partially encircling the first piston in the first bore and configured to move at least in a direction parallel to the first axis of translation such that in a first close position the first sleeve valve is configured to be urged into contact with the first valve seat.
  2. An opposed piston internal combustion engine as in any of claims 1 to 6, further comprising: a second sleeve valve associated with the second piston to control the opening and closing of an exhaust port for allowing removal of combustion gases from the combustion chamber, the second sleeve valve at least partially encircling the second piston in the second bore and moving at least in a direction parallel to the second axis of translation such that in a second close position the second sleeve valve is urged into contact with the second valve seat;
  3. A method comprising: reciprocating a first piston between a first top dead center position along a first axis of translation within a first cylinder bore in an engine block of an opposed piston internal combustion engine, the first piston comprising a first distant crown ;

rotating the first crankshaft under influence of the reciprocating of the first piston, the first crankshaft disposed closer to the first bottom dead center position than to the first top dead center position;

reciprocating a second piston between a second top dead center position and a second bottom dead center position along a second axis of translation within a second cylinder bore in the engine block, the second axis of translation being inclined at an included angle relative to the first axis of translation, the included angle having a vertex that is closer to the first and the second top dead center position is than to the first and second bottom dead center positions, the second piston comprising a second piston crown, the second piston crown and the first piston crown at least partially defining a combustion chamber within the opposed piston internal combustion engine;

and

rotating a second crankshaft under influence of the reciprocating of the second piston, the second crankshaft disposed closer to the second bottom dead center position than to the second top dead center position.

  1. A method as in any of claims 13 to 17, wherein the first sleeve valve is associated with the first piston to control opening and closing of an inlet port for allowing delivery of at least one of fuel and air to the combustion chamber, the first sleeve valve at least partially encircling the first piston in the first bore and moving at least in a direction parallel to the first axis of translation such that in the first closed position the first sleeve valve is urged into contact with the first valve seat.
  2. A method as in any of claims 13 to 18, wherein a second sleeve valve is associated with a second piston to control the opening and closing of an exhaust port for allowing removal of combustion gases from the combustion chamber, the second sleeve valve at least partially encircling the second piston in the second bore and moving at least in a direction parallel in the second axis of translation such that in a second enclosed position the second sleeve valve is urged into contact with the second valve seat.”
  3. Upon publication on 14 February 2014, followed by request for examination dated 01 April 2014, the FER was issued on 07 December 2018. As is evident from the original claims set out above, the two features emphasised by learned counsel for the appellants as establishing inventive step: (i) the provision of a crank offset between the first piston and the first crankshaft and, likewise, the provision of a crank offset between the second piston and the second crankshaft; and (ii) the rotation of the two crankshafts in opposite directions, were not claimed in the original set of claims. It is also noticeable that such crank offset is not seen in the drawings forming part of the complete specification, such as Figures 2 and 5. In the FER, as mentioned earlier, in the context of the original set of claims set out above, objections were raised inter alia on the ground of lack of inventive step by citing prior arts D1-D5. In response, the appellants amended the original set of claims by merging original claims 6 and 7 with original independent claim 1 and similarly merging original claims 18 and 19 with original independent claim 13. Consequently original claims 6, 7, 18 and 19 were deleted and the claims were renumbered as claims 1-20. It is pertinent to point out that, even at this stage, the claims were not amended to include the crank offset or the crankshaft rotation features discussed above.
  4. In response, by hearing notice dated 10 June 2020, the same objections were maintained in view of the same prior art (D1-D5). After the oral hearing, along with the written submissions, the current claims were filed by amending independent claims 1 and 11. The changes were by way of incorporation of the crank offset and crankshaft rotation features. The crank offset and the crankshaft rotation features were, however, contained in paragraph [0049] of the complete specification as an option. Current independent claims 1 and 11 are set out below by emphasising in bold font the changes:

“1. An opposed piston internal combustion engine (200, 300, 400, 500) comprising:

a first piston (104) reciprocating along a first axis of translation (202) within a first cylinder bore (502) in an engine block, the first piston (104) reciprocating between a first top dead center position and a first bottom dead center position, the first piston (104) comprising a first piston crown (102);

a first crankshaft (136) configured to be rotated under influence of the reciprocating of the first piston, the first crankshaft (136) disposed close to the first bottom dead center position than to the first top dead center position; and a first sleeve valve (122) associated with the first piston (104) to control opening and closing of an inlet port (116) for allowing delivery of at least one of fuel and air to the combustion chamber (114), the first sleeve valve (122) at least partially encircling the first piston (104) in the first bore and configured to move at least in a direction parallel to the first axis of translation (202) such that in a first close position the first sleeve valve (122) is configured to be urged into contact with the first valve seat (128); a second piston (110) reciprocating along a second axis of translation (204) within a second cylinder bore (504) in the engine block, the second piston (110) reciprocating between a second top dead center position and a second bottom dead center position, the second axis of translation (204) being inclined at an included angle relative to the first axis of translation, the included angle having a vertex that is closer to the first and the second top dead center position is than to the first and second bottom dead center positions, the second piston (110) comprising a second piston crown (106), the second piston crown (106) and the first piston crown (102) at least partially defining a combustion chamber (114) within the opposed piston internal combustion engine;

a second crankshaft (138) configured to be rotated under influence of the reciprocating of the second piston (110), the second crankshaft (138) disposed closer to the second bottom dead center position that the second top dead center position; and a second sleeve valve (124) associated with the second piston (110) to control the opening and closing of an exhaust port (120) for allowing removal of combustion gases from the combustion chamber (114), the second sleeve valve (124) at least partially encircling the second piston (110) in the second bore and moving at least in a direction parallel to the second axis of translation (204) such that in a second close position the second sleeve valve (124) is urged into contact with the second valve seat (130);

wherein a first crank offset is provided between the first piston (104) and the first crank shaft (136), and a second crank offset is provided between the second piston (110) and the second crankshaft (138), wherein, by the provision of the first crank offset and the second crank offset, the first crank offset (136) and the second crankshaft (138) are rotatable in opposite directions.

  1. A method comprising:

reciprocating a first piston (104) between a first top dead center position Along a first axis of translation (202) within a first cylinder bore (502) in an engine block of an opposed piston internal combustion engine, the first piston (104) comprising a first piston crown (102); rotating the first crankshaft (136) under influence of the reciprocating of the first piston, the first crankshaft (136) disposed closer to the first bottom dead center position that the first top dead center position, wherein the first sleeve valve (122) is associated with a first piston (104) to control opening and closing of an inlet port (116) for allowing delivery of at least one of fuel and air to the combustion chamber (114), the first sleeve valve (122) at least partially encircling the first piston (104) in the first bore and moving at least in a direction parallel to the first axis of translation (202) such that in the first closed position the first sleeve valve (122) is urged into contact with the first valve seat (128);

reciprocating a second piston (110) between a second top dead center position and a second bottom dead center position along a second axis of translation (204) within a second cylinder bore (504) in the engine block, the second axis of translation (204) being inclined at an included angle relative to the first axis of translation, the included angle having a vertex that is closer to the first and the second top dead center position is that the first and second bottom dead center positions, the second piston (110) comprising a second piston crown (106), the second piston crown (106) and the first piston crown (102) at least partially defining a combustion chamber (114) within the proposed piston internal combustion engine; and rotating a second crankshaft (138) under influence of the reciprocating of the second piston (110), the second crankshaft (138) disposed closer to the second bottom dead center position than to the second top dead center position, wherein a second sleeve valve (104) is associated with a second piston (110) to control the opening and closing of an exhaust port (120) for allowing removal of combustion gases from the combustion chamber (114), the second sleeve valve (104) at least partially encircling the second piston (110) in the second bore and moving at least in a direction parallel to the second axis of translation (204) such that in a second enclosed position the second sleeve valve (104) is urged into contact with the second valve seat (130);

wherein a first crank of set is provided between the first piston (104) and the first crankshaft (136), and a second crank of set is provided between the second piston (110) and the second crankshaft (138) wherein, by the provision of the first crank offset and the second crank offset, the first crankshaft (136) and the second crankshaft (138) are rotatable in opposite directions.” [emphasis added]

  1. The impugned order was pronounced in these facts and circumstances. After discussing prior arts D1, D3 and D5, the operative portion of the impugned order is as under:

 “With it is the basic design change item which it easily can work out it is recognised to the normal technical engineer to form the opposed piston internal combustion engine which comprises “a first crankshaft, a first sleeve valve, a second piston, a second crankshaft, a second sleeve valve.” Therefore, claims 1 and 11 invention can be invented by the normal technical engineer based on the cited invention.

Hence the present invention lacks inventive step according to section 2(1)(ja) of The Patents Act, 1970 and a person skilled in the art will be motivated by the above cited documents to  conclude the invention.”

  1. In the above extract, the Assistant Controller merely set out the various elements of the claimed invention such as the opposed pistons, the two crankshafts and the two sleeve valves and proceeded to record the conclusion that the claimed invention would be obvious to a normal technical engineer based on cited prior arts. I find no analysis or discussion of the features of the claimed invention, including with regard to the provision of a crank offset between the first piston and the first crankshaft and likewise between the second piston and the second crankshaft or the rotation of the two crankshafts in opposite directions. Consequently, the impugned order is effectively unreasoned and cannot be sustained.

 

  1. The question that follows is whether the matter should be remanded after setting aside the impugned order or whether the patent application should be directed to proceed to grant. Before drawing conclusions, the prior art should be discussed. Prior art D1 is an invention titled “New Opposed Piston Type Two Stroke Cycle Engine”. From paragraph [0002] of the complete specification, it appears that the solution claimed and disclosed therein is the prevention of cooling loss at low and medium speed operation. As in the case of the claimed invention, it is clear from Figure 1 therein that the two cylinders and pistons are inclined downward from the combustion chamber, thereby creating a larger combustion chamber without using the larger space that would have been required to form an equal sized combustion chamber if the cylinders and pistons were not inclined relative to the combustion chamber. The crank offset and crankshaft rotation features are, however, neither claimed nor shown in the drawings forming part of D1.
  2. D3 is an invention titled “Twin-Piston-Per Cylinder Engine”. Since D3 was cited as the closest prior art, I set out below the summary, in relevant part:

 “…. In a preferred form of the invention, the cylinders may be disposed in generally horizontally opposed relation inclined slightly downwardly away from the common combustion chamber. This provides an effective combustion chamber design with minimum piston clearance at the bottom of the chamber while allowing ample room at the top of the chamber for a spark plug (in an S.I. engine) and inlet and exhaust valves….” When this is compared with paragraphs [0030] and [0031] of the complete specification of the claimed invention, there is similarity in the design of the cylinders, pistons and the common central combustion chamber defined by these elements. However, as contended by learned counsel for the appellant, Figures 1 and 3 of D3 show that the crankshaft is aligned with the cylinders and not off set.

D5 describes an internal combustion engine having reciprocating piston sleeves that comprise an engine block with a pair of cylinders with each cylinder having an intake port, an exhaust port and two linear opposing pistons connecting to two opposing crankshafts. In D5, a pair of piston sleeves are reciprocating in each cylinder, one piston sleeve around each piston. Each piston sleeve is connected to one of two eccentric shafts that run parallel and adjacent to each crankshaft. As in the case of D3, from Figures 8 and 9 of D5, it appears that the crankshaft is aligned with the cylinders and not off set.

  1. Thus, as regards the crank offset and rotation of crankshaft features, these features are not found in D1, D3 & D5. There is no teaching, suggestion or motivation either in D1, D3 & D5 that would make these features obvious to a person skilled in the art. Nonetheless, as discussed earlier, independent claims 1 and 11 were modified to incorporate these features at the written submissions stage after the oral hearing. Since these features were recited as an option in paragraph [0049] of the complete specification of the claimed invention, the amendment is within the scope of the complete specification and is liable to be allowed as per Section 59 of the Patents Act.
  2. Even so, it appears that prior art with regard to the inventive features claimed above, i.e. crank offsets and rotation of crankshafts, were not considered by the Assistant Controller probably in view of the amendments being made at the written submissions stage. From my survey of prior art in the field of endeavour, it appears there could be other relevant prior art. In these circumstances, I am not inclined to direct that the application proceed to grant. Instead, the application is remanded for reconsideration on the limited aspect outlined above. In order to preclude the possibility of pre-determination, any officer other than the officer who issued the impugned order shall undertake reconsideration. Since about 12 years have elapsed from the date of application, it is directed that Indian Patent Application No.8612/CHENP/2012 be disposed of within a maximum period of three months from the date of receipt of a copy of this order by a speaking order.”

Citation: Pinnacle Engines Inc. v. The Assistant Controller of Patents & Designs, (T)CMA(PT)/17/2023, 2024:MHC:1951 (H.C. Madras April 30, 2024). Available at: http://indiankanoon.org/doc/68115546/, Visited on: 02/07/2024.

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