An engine for a vehicle

Abstract

The present invention provides an engine for a vehicle comprising a plurality of intake valves; a plurality of exhaust valves; at least a camshaft comprising a plurality of intake cam lobes fixedly mounted on the intake camshaft and configured to operate at least plurality of intake valves and a plurality of exhaust cam lobes fixedly mounted on the exhaust camshaft and configured to operate at least plurality of exhaust valves; wherein the number of intake cam lobes are equivalent to the number of intake valves and the number of exhaust cam lobes are equivalent to the number of exhaust valves; wherein the intake cam lobes operating the intake valves are relatively at different angles with respect to each other and / or the exhaust cam lobes operating the exhaust valves are relatively at different angles with respect to each other.

Description

[0001] AN ENGINE FOR A VEHICLE

[0002] FIELD OF INVENTION:

[0003]

[0001] The present invention relates to an engine for a vehicle and more particularly relates to a camshaft of a valve train used in automotive engine.

[0004] BACKGROUND OF INVENTION:

[0005]

[0002] Generally, an automotive engine is provided with plurality of valves, like an intake valve(s) and an exhaust valve(s), which are operated by single or more than one camshaft(s). The camshaft comprises of cam lobes on its surface. The camshaft is rotated using power from engine crankshaft, which causes the cam lobes to push the valve stems against a spring force thereby operating the valves. The instant opening or closing of the valves against valve seat surface allows intake charges to enter the cylinder (during intake valve opened stage) and expel out combustion byproducts (during exhaust valve opened stage), these are important aspects in the operation of the engine. It is the governing factors for engine power and torque. As stated previously, camshafts can be configured in various constructions such as a) Double Overhead Camshaft (DOHC) which utilizes pad rocker arms, roller rocker arms, or cam lobes directly acting on bucket shims, b) Single Overhead Camshaft (SOHC) which utilizes a single camshaft in the centre actuating both the exhaust and intake valves through corresponding rocker arms, c) Pushrod Construction which utilizes cam lobe motion transmitted through pushrods, bridges, and rocker arms to actuate the valves, and d) Valve Spring-less Actuation which utilizes desmodromic cams to control the valve lift without valve springs.

[0006]

[0003] Typically, a single cylinder engine is provided with at least two valves i.e. an intake valve and an exhaust valve being operated by the cam lobes of the camshaft, wherein the cam lobes are fixed at particular location on the camshaft. The engine can be provided with two valves or more than two valves i.e. at least two intake valves and at least an exhaust valve. The location and profile of the cam lobes are decided based on the desired valve timing. The primary function of the camshaft configuration is to lift the valves, allowing intake charges to enter the cylinder and exhaust valves to expel out combustion by-products. The ideal cam lift curve features, abrupt opening and closing to maximize intake charge and efficiently expel combustion byproducts. This abrupt action is achieved through multi-degree polynomial or spline camshaft profiles, with opening and landing dynamics managed by the cams opening and closing ramps. The cam lobe parameters such as cam lobe velocity, lift in the ramp, combined with spring force, and the moving mass of the valve train system are critical in influencing valve seating dynamics, and eventually affects engine performance, emissions, and NVH (Noise, Vibration, and Harshness). While abrupt valve closure and opening improve engine performance and emissions, they can negatively impact the durability of valve train components and NVH, particularly in open engines like those in two- wheelers where noise is highly perceptible and can be irritating to customers.

[0007]

[0004] Various solutions exist to mitigate these issues, such as incorporating hydraulic tappet elements to reduce NVH during valve operation. However, these solutions often involve costly interfacial components, making them economically unfeasible for low-cost two-wheelers. Moreover, the noise from valve seating and opening becomes significantly more pronounced in four-valve engines or multicylinder engines, where optimizing camshaft ramp parameters to reduce noise (without affecting engine performance and emission values) and bring it within customer acceptable limit is a technically challenging task, since such changes increase complexity of camshaft design, number of components and overall cost.

[0008]

[0005] Thus, there is a need in the art for an arrangement in a single cylinder engine which improves the NVH of the engine while maintaining the engine performance and mandatory emission requirements and addresses at least the aforementioned problems. OBJECTIVES OF THE INVENTION:

[0009]

[0006] An object of the present disclosure is to ameliorate limitations of the existing prior art by providing an improved system of camshaft of an engine.

[0010]

[0007] Another objective of the present disclosure is to improve the NVH of the engine without affecting the engine performance and emission requirements.

[0011]

[0008] Yet another objective of the invention is to reduce the noise generated due to interaction between a valve seat and a tappet valve in a four valve engine.

[0012]

[0009] Another objective of the present invention is to improve the power output of the engine by strategizing the valve timings.

[0013]

[0010] Other obj ects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.

[0014] SUMMARY OF THE INVENTION:

[0015] [OH] With these objectives in view, the present invention provides an engine for a vehicle comprising: a plurality of intake valves configured to allow entry of intake charge into a cylinder of the engine; a plurality of exhaust valves configured to allow exit of the combusted gases from the cylinder of the engine; at least a camshaft comprising a plurality of intake cam lobes fixedly mounted on the camshaft and configured to operate at least the plurality of the intake valves and a plurality of exhaust cam lobes fixedly mounted on the camshaft and configured to operate at least the plurality of exhaust valves; wherein the number of intake cam lobes are equivalent to the number of intake valves and the number of exhaust cam lobes are equivalent to the number of exhaust valves; wherein the intake cam lobes operating the intake valves are relatively at different angles with respect to each other and / or of the exhaust cam lobes operating the exhaust valves are relatively at different angles with respect to each other.

[0016]

[0012] According to one of the embodiment, the plurality of intake valves includes at least two intake valves and the plurality of exhaust valves includes at least two exhaust valves.

[0017]

[0013] According to one another embodiment, the plurality of intake cam lobes are provided on an intake camshaft and the plurality of exhaust cam lobes are provided on an exhaust camshaft. The intake valves and exhaust valves are operated by the plurality of intake cam lobes and the plurality of exhaust cam lobes through a plurality of mechanical tappet.

[0018]

[0014] In another embodiment, the plurality of cam lobes is provided on single camshaft, wherein the plurality of intake valves and the exhaust valves are operated by the plurality of cam lobes fixedly mounted on the single camshaft. The cam lobes on the camshafts rotatably transmit motion to the valves through translational movement of the plurality of mechanical tappet existing between the cam lobes and the valves.

[0019]

[0015] According to yet another embodiment, the intake camshaft having at least two intake cam lobes are at different angles with respect to each other, wherein the phase angle between the intake cam lobes is in the range of 1 degree to 10 degrees.

[0020]

[0016] According to yet another embodiment, the intake cam lobes at relative different angle with each other, facilitates in sequential valve operations and mitigates the simultaneous impact noise the valve and corresponding valve seat.

[0017] According to yet another embodiment, the exhaust camshaft having at least two exhaust cam lobes are at different angles with respect to each other, wherein the phase angle between the exhaust cam lobes is in the range of 1 degree to 10 degrees.

[0021]

[0018] According to yet another embodiment, the exhaust cam lobes at relative different angle with each other facilitates in sequential valve operations and mitigates the simultaneous impact noise between the valve and the corresponding valve seat.

[0022]

[0019] The engine according to present invention is a single cylinder engine; wherein a set of camshafts namely intake camshaft and exhaust camshaft having two cam lobes on each camshaft, wherein the cam lobes on each camshafts are approximately at 1 - 10 degrees phase angle.

[0023]

[0020] According to yet another embodiment, the plurality of intake valves and the exhaust valves according to present invention are employed on any type of engine including single cylinder, and multi cylinder and on any kind of vehicle including two-wheeled, three-wheeled and four-wheeled vehicle.

[0024] BRIEF DESCRIPTION OF DRAWINGS:

[0025]

[0021] The above and other objects, features, and advantages of the present disclosure will be more apparent from the detailed description taken in conjunction with the accompanying drawings. One or more embodiments of the present invention are now described, by way of example only with reference to the accompanied drawings wherein like reference numerals represent like elements:

[0022] Fig. 1 illustrates an isometric three-dimensional view of an engine with a cylinder head cover removed, according to an embodiment of the present disclosure;

[0023] Fig. 2a illustrates an isometric view showing valve train of the engine, according to an embodiment of the present disclosure;

[0026]

[0024] Fig. 2b illustrates a top view of the cylinder head of the engine, according to an embodiment of the present disclosure;

[0027]

[0025] Fig. 3a illustrates an intake camshaft and Fig. 3b illustrates cam lobes of the intake camshaft through section A-A of the intake camshaft of Fig. 3a, according to an embodiment of the present disclosure;

[0028]

[0026] Fig. 4a illustrates an exhaust camshaft and Fig. 4b illustrates cam lobes of the exhaust camshaft through section B-B of the exhaust camshaft of Fig. 4a, according to an embodiment of the present disclosure;

[0029]

[0027] Figs. 5a - 5f illustrate different position of plurality of valves of one of the camshaft, according to an embodiment of the present disclosure;

[0030]

[0028] Fig. 6a illustrates an isometric view showing valve train of the engine, according to an embodiment of the present disclosure; and

[0031]

[0029] Fig. 6b illustrates an isometric view showing cam shaft of the engine, according to an embodiment of the present disclosure;

[0032] DETAIL DESCRIPTION OF DRAWINGS:

[0033]

[0030] A preferred embodiment will now be described in detail with reference to the accompanying drawings. The preferred embodiment does not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.

[0034]

[0031] It will be readily understood that components of present invention as generally described and illustrated in figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the invention as represented in the figures is not intended to limit the scope of the invention but is merely representative of certain examples of presently contemplated embodiments in accordance with the invention. The presently described embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.

[0035]

[0032] Fig. 1 illustrates an engine (100) for an automotive vehicle comprises of a cylinder head (102) located above a cylinder block (104) and a crankcase (106). Fig. 2a illustrates an isometric view of a valve train (200). The cylinder head comprises plurality of intake valves (108a, 108b) configured to allow entry of intake charge into a cylinder (110) of the engine (100) and a plurality of exhaust valves (112a, 112b) configured to allow exit of the combusted gases from the cylinder (110) of the engine (100). The cylinder head (102) comprises plurality of camshafts (114, 118) which operates the plurality of intake valves (108a, 108b) and the plurality of exhaust valves (112a, 112b). The plurality of intake valves (108a, 108b) and the plurality of exhaust valves (112a, 112b) are operated through fixedly mounted a plurality of intake cam lobes (116a, 116b) on the intake camshaft (114) and a plurality of exhaust cam lobes (120a, 120b) on the exhaust camshaft (118) respectively. The intake camshaft (114) comprises two intake cam lobes (116a, 116b) to operate the two intake valves (108a, 108b) and the exhaust camshaft (118) comprises of two exhaust cam lobes (120a, 120b) to operate the two exhaust valves (112a, 112b). The cam lobes (116a, 116b, 120a, 120b) on the camshafts (114, 118) rotatably transmit motion to the valves (108a, 108b, 112a, 112b) through translational movement of plurality of mechanical tappet (122) existing between the cam lobes (116a, 116b, 120a, 120b) and the valves (108a, 108b, 112a, 112b). The plurality of camshafts (114, 118) includes cam sprockets (124) fixed at one extreme end configured to rotate the camshafts (114, 118). As shown in Fig. 2a, the number of cam lobes (116a, 116b, 120a, 120b) provided are equivalent to the number of valves (108a, 108b, 112a, 112b). Fig. 2b illustrates a top view of a valve train (200). The intake camshaft (114) comprising the two intake cam lobes (116a, 116b) positioned near a mid-point (114a) of the intake camshaft (114) and at an extreme end (114b) of the intake camshaft (114). The sprocket (124) is mounted at another extreme end (114c) of the intake camshaft (114). The exhaust camshaft (118) comprising the two exhaust cam lobes (120a, 120b) positioned near a mid- point (118a) of the exhaust camshaft (118) and at an extreme end (118b) of the intake camshaft (118). Another sprocket (124) is mounted at another extreme end (118c) of the exhaust camshaft (118).

[0036]

[0033] Fig. 3a illustrates the intake camshaft (114) comprising the two intake cam lobes (116a, 116b) positioned near the mid-point of the camshaft (114a) and at an extreme end (114b), and the cam sprocket (124) mounted at another extreme end (114c). The intake cam lobe (116a) positioned near the mid-point (114a) of the camshaft (114) is closer to the chain pocket side and is termed as inner cam lobe (116a) and the intake cam lobe (116b) positioned at the other extreme end (114b) is farther from the chain pocket side and is termed as outer cam lobe (116b). Fig. 3b illustrates the side view of the two cam lobes of the intake camshaft viewed through section A- A of the intake camshaft of Fig. 3 a, illustrating that an angle or a phase angle (alpha or “a”) between the inner cam lobe (116a) and the outer cam lobe (116b) of the intake camshaft. The phase angle (alpha or “a”) between the inner cam lobe (116a) and the outer cam lobe (116a) mounted on the intake camshaft (114) facilitates in sequential valve operations and mitigates the simultaneous impact noise between the intake valves (108a, 108b) and corresponding valve seat (not shown), since both the valves do not impact or seats on the valve-seat at once.

[0037]

[0034] Fig. 4a illustrates the exhaust camshaft (118) comprising the two exhaust cam lobes (120a, 120b) positioned near the mid-point of the camshaft (118a) and at an extreme end (118b), and the cam sprocket (124) mounted at another extreme end (118c). The exhaust cam lobe (120a) positioned near the mid-point (118a) of the camshaft (118) is closer to the chain pocket side and is termed as inner cam lobe (120a) and the cam lobe (120b) positioned at the other extreme end (118b) is farther from the chain pocket side and is termed as outer cam lobe (120b). Fig. 4b illustrates the side view of the two cam lobes of the exhaust camshaft viewed through section B-B of the exhaust camshaft of Fig. 4a, illustrating that an angle or a phase angle (beta or “P”) between the inner cam lobe (120a) and the outer cam lobe (120b) of the exhaust camshaft (118). The phase angle (beta or “P”) between the inner cam lobe (120a) and the outer cam lobe (120b) mounted on the exhaust camshaft (118) facilitates in sequential valve operations and mitigates the simultaneous impact noise between the exhaust valves (112a, 112b) and corresponding valve seat (not shown), since both the valves do not impact or seats on the valve-seat at once.

[0038]

[0035] The phase angle (alpha (a), beta ( )) provided between the inner cam lobes and the outer cam lobes of both the intake camshaft and the exhaust camshaft is in the range of 1 degree to 10 degrees. The optimization of the phasing of the cam lobes considers structural excitations on cylinder head castings, engine performance, and emission performance. Additionally, the phasing value for cam lobes is optimized to account for manufacturing variations, ensuring consistent performance and noise reduction.

[0039]

[0036] Figs. 5a - 5f illustrate different position (lift) of the plurality of valves with respect to different crank angle. The valve lift of the plurality of valves are corresponding to the inner cam lobes and the outer cam lobes mounted on the camshaft. The valve corresponding to the outer cam lobe (304) is termed as valve 1 and the valve corresponding to the inner cam lobe (302) is termed as valve 2 . The first position shows both the valve 1 and the valve 2 are fully seated on the valve seat i.e., they are fully closed, shown in the Fig. 5a. At certain rotation of the camshaft, the valve 1 is in partially open state and the valve 2 is at fully seated on the valve seat, shown in the Fig. 5b. At further rotation of the camshaft, the valve 1 is in fully open state and the valve 2 is in partially open state, shown in the Fig. 5c. Further, Fig. 5d shows the valve 1 is in partially open state and the valve 2 is at fully open state. Fig. 5e shows the valve 1 is in fully closed state and the valve 2 in fully open state. Fig. 5f shows both the valve 1 and the valve 2 are again in fully seated state on the valve seat.

[0040]

[0037] Fig. 6a illustrating an isometric view of a valve train (400) and Fig. 6b illustrating an isometric view of a single camshaft (402) of an engine. The present invention may include an engine ( 100) having a cylinder (403) comprising a plurality of cam lobes (404a, 404b, 406a, 406b) provided on a single camshaft (402), wherein a plurality of intake valves (408a, 408b) and a plurality of exhaust valves (410a, 410b) are operated by the plurality of cam lobes (404a, 404b, 406a, 406b) fixedly mounted on the single camshaft (402). The plurality of cam lobes (404a, 404b, 406a, 406b) includes plurality of intake cam lobes (404a, 404b) and plurality of exhaust cam lobes (406a, 406b). The plurality of cam lobes (404a, 404b, 406a, 406b) on the single camshaft (402) rotatably transmit motion to the valves (408a, 408b, 410a, 410b) through translational movement of the plurality of mechanical tappet (412) existing between the cam lobes (404a, 404b, 406a, 406b) and the valves (408a, 408b, 410a, 410b). The single camshaft (402) having two intake cam lobes (404a, 404b) are at different phase angle with respect to each other, wherein the phase angle between the cam lobes is in the range of 1 degree to 10 degrees. The intake cam lobes (404a, 404b) at relatively different phase angle with each other, facilitates in sequential valve operations and mitigates the simultaneous impact noise the intake valve (408a, 408b) and corresponding valve seat (not shown). The single camshaft (402) having two exhaust cam lobes (406a, 406b) at different phase angle with respect to each other, wherein the phase angle between the cam lobes is in the range of 1 degree to 10 degrees. The exhaust cam lobes (406a, 406b) at relatively different angle with each other facilitates in sequential valve operations and mitigates the simultaneous impact noise between the exhaust valve (406a, 406b) and the corresponding valve seat (not shown).

[0041]

[0038] The present invention is applicable in a single cylinder engine; wherein a set of camshafts namely intake camshaft and exhaust camshaft having two cam lobes on each camshaft, wherein the cam lobes on each camshaft are approximately at 1 - 10 degrees phase angle.

[0042]

[0039] The present invention is applicable to any type of vehicle including twowheeled, three wheeled or four wheeled vehicles including at least one camshaft having intake valve and exhaust valve. Therefore, the number of camshafts defined herein are not to limit the scope of present invention.

[0043]

[0040] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics or essential characteristics. The described embodiments are to be considered in respects as illustrative and not restrictive.

[0044]

[0041] Although the exemplary forms of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the present disclosure.

[0045] List of Reference Numerals:

[0046] 100 - Engine

[0047] 102 - Cylinder head

[0048] 104 - Cylinder block

[0049] 106 - Crankcase

[0050] 108a, 108b - Plurality of Intake valves

[0051] 110 - Cylinder of the engine

[0052] 112a, 112b - Plurality of Exhaust valves

[0053] 114 - Intake camshaft

[0054] 114a - Mid-point of the intake camshaft

[0055] 114b - Extreme end of the intake camshaft

[0056] 114c - Another extreme end of the intake camshaft

[0057] 116a, 116b - Cam lobes for intake valves 118 - Exhaust camshaft

[0058] 118a - Mid-point of the exhaust camshaft

[0059] 118b - Extreme end of the exhaust camshaft

[0060] 118c - Another extreme end of the intake camshaft 200 - Valve train

[0061] 120a, 120b - Cam lobes for exhaust valves

[0062] 122 - Plurality of mechanical Tappet

[0063] 124 - Cam sprockets

[0064] 302 - Inner cam lobe 304 - Outer cam lobe

[0065] 400 - Valve train

[0066] 402 - Single camshaft

[0067] 403 - Cylinder

[0068] 404a, 404b - Plurality of Intake cam lobes 406a, 406b - Plurality of Exhaust cam lobes

[0069] 408a, 408b - Plurality of Intake valves

[0070] 410a, 410b - Plurality of Exhaust valves

[0071] 412 - Plurality of Mechanical tappet

Claims

ClaimsWe Claim:

1. An engine (100) for a vehicle, comprising: a plurality of intake valves (108a, 108b, 408a, 408b) configured to allow entry of intake charge into a cylinder (110, 403) of the engine (100,); a plurality of exhaust valves (112a, 112b, 410a, 410b) configured to allow exit of the combusted gases from the cylinder (110, 403) of the engine (100); at least a camshaft (114, 118, 402) comprising a plurality of intake cam lobes (116a, 116b, 404a, 404b) fixedly mounted on the camshaft (114, 402) and configured to operate at least the plurality of the intake valves (108a, 108b, 408a, 408b) and a plurality of exhaust cam lobes (120a, 120b, 406a, 406b) fixedly mounted on the camshaft (118, 402) and configured to operate the plurality of exhaust valves (112a, 112b, 410a, 410b); wherein the number of intake cam lobes (116a, 116b, 404a, 404b) are equivalent to the number of intake valves (108a, 108b, 408a, 408b) and the number of exhaust cam lobes (120a, 120b, 406a, 406b) are equivalent to the number of exhaust valves (112a, 112b, 410a, 410b); wherein the intake cam lobes (116a, 116b, 404a, 404b) operating the intake valves (108a, 108b, 408a, 408b) are positioned relatively at different phase angle with respect to each other and / or the exhaust cam lobes (120a, 120b, 406a, 406b) operating the exhaust valves (112a, 112b, 410a, 410b) are positioned relatively at different phase angle with respect to each other.

2. The engine (100) for a vehicle as claimed in claim 1, wherein the plurality of intake valves includes two intake valves (108a, 108b) and the plurality of exhaust valves includes two exhaust valves (120a, 120b).

3. The engine (100) for a vehicle as claimed in claim 1, wherein the camshaft (114, 118) comprises an intake camshaft (114) and an exhaust camshaft (H8).

4. The engine (100) for a vehicle as claimed in claim 3, wherein the plurality of intake cam lobes (116a, 116b) are fixedly mounted on the intake camshaft (114) and the plurality of exhaust cam lobes (120a, 120b) are fixedly mounted on the exhaust camshaft (118).

5. The engine (100) for a vehicle as claimed in claim 1, wherein the intake valves (108a, 108b) and exhaust valves (112a, 112b) are operated by the plurality of intake cam lobes (116a, 116b) and the plurality of exhaust cam lobes (120a, 120b) through a plurality of mechanical tappets (122).

6. The engine (100) for a vehicle as claimed in claim 1, wherein the phase angle between the intake cam lobes (116a, 116b) is in a range from 1 degree to 10 degrees and a phase angle between the exhaust cam lobes (120a, 120b) is in a range from 1 degree to 10 degrees.

7. The engine (100) for a vehicle as claimed in claim 1, wherein the plurality of intake cam lobes (404a, 404b) and exhaust cam lobes (406a, 406b) are provided on the camshaft (402).

8. The engine (100) for a vehicle as claimed in claim 1, wherein the engine (100) is a single cylinder engine.

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