GB2546985A

GB2546985A - Valve apparatus for an engine

Info

Publication number: GB2546985A
Application number: GB1601850.9A
Authority: GB
Inventors: Berger Olaf; Schelle Jorg; Veltman Matthias
Original assignee: Caterpillar Energy Solutions GmbH
Current assignee: Caterpillar Energy Solutions GmbH
Priority date: 2016-02-02
Filing date: 2016-02-02
Publication date: 2017-08-09
Also published as: GB201601850D0

Abstract

Disclosed is a valve apparatus 130 for controlling the opening and closing of a valve of an internal combustion engine 100. The valve apparatus comprises a camshaft 132 having a first cam 136 configured to open a valve 126 during a first cycle period of the internal combustion engine and a second cam 138 configured to open the valve during a second cycle period of the internal combustion engine and a controller 134 having at least a first mode of operation and a second mode of operation. The controller in the first mode of operation is configured to permit opening of the valve 126 by the first cam 136 and the second cam 138. The controller in the second mode of operation is configured to prevent opening of the valve by the first cam. The controller 134 may be a hydraulic controller. The arrangement is used to cause an exhaust valve to open slightly during the compression stroke of the engine to relieve pressure in a combustion chamber when an electronic control unit determines that the pressure in the combustion chamber is likely to be above a specified limit.

Description

Valve Apparatus for an Engine

Technical Field [0001] The present disclosure relates to an internal combustion engine. In particular, the present disclosure relates to a valve apparatus for an internal combustion engine.

Background [0002] An internal combustion engine (ICE) is a heat engine where combustion of a fuel occurs in the presence of an oxidizer (usually air) in a combustion chamber. During combustion of the fuel in the internal combustion engine high-temperature and high-pressure gases are produced which apply direct force on some components of the engine. The force is applied typically to a piston and moves the piston over a distance, transforming chemical energy into useful mechanical energy.

[0003] A typical internal combustion engine ignites the air-fuel mixture within the cylinders to provide torque. A spark generated by an ignition plug ignites the air-fuel mixture within the combustion chamber.

[0004] However, during operation of the engine, excess fuel may be introduced in the combustion chamber due to incorrect operation of the injection system. As a result the air fuel ratio changes from a leaner to a richer mixture. These changes in the air fuel ratio may increase the pressure in the combustion chamber which may cause sudden self-ignition of the air-fuel mixture. The high pressure peaks caused by sudden self-ignition accompanied by the high combustion velocity of the air-fuel mixture may cause damage to the cylinders, pistons, and valves.

[0005] In typical engines, an engine control unit may detect this incorrect operation of the injection system and may modify the ignition process within the combustion chamber. The engine control unit may either delay the ignition timing of the air-fuel mixture present within the combustion chamber or the engine control unit may stop ignition within the combustion chambers.

[0006] However, even when the ignition timing is delayed, the mechanical overload on the driving gears is not prevented and may cause damage to the engine. Further, during operation the pressure and temperature within the combustion chamber may be sufficient to auto-ignite the air-fuel mixture.

[0007] Furthermore, certain engine systems may be equipped with turbocharger systems configured to introduce pressurized air into the combustion chamber. The high pressure of the air introduced in the cylinders may promote high pressure being developed in the combustion chamber. Due to this, even if the engine control unit ceases the ignition within the combustion chambers, the high pressure created by turbocharging may cause auto-ignition.

[0008] US Patent No. 4,982,706 discloses a hydraulic valve control apparatus for an internal combustion engine. The hydraulic valve control apparatus includes a valve piston and a piston portion. The valve piston and the piston portion define a stroke transmission chamber. Further, US Patent No. 4,982,706 discloses a magnetic control valve controlling the quantity of oil present in the stroke transmission chamber to control the amount of fuel and air mixture aspirated into the combustion chamber.

Summary of the Invention [0009] In an aspect of the present disclosure, a valve apparatus for controlling the opening and closing of a valve of an internal combustion engine is disclosed. The valve apparatus has a camshaft having a first cam configured to open the valve during a first cycle period of the internal combustion engine and a second cam configured to open the valve during a second cycle period of the internal combustion engine and a controller having at least a first mode of operation and a second mode of operation.

[0010] In yet another aspect of the present disclosure, an engine system is disclosed. The engine system has a valve, a camshaft having a first cam configured to open the valve during a first cycle period of the internal combustion engine and a second cam configured to open the valve during second cycle period of the internal combustion engine and a controller having a first mode of operation and a second mode of operation wherein in the first mode of operation the controller is configured to permit opening of the valve by the first cam and the second cam and in the second mode of operation the controller is configured to prevent opening of the valve by the first cam.

[0011] In yet another aspect of the present disclosure, a method of controlling opening and closing a valve of an engine, the engine comprising a camshaft having a first cam configured to open the valve during a first cycle period and a second cam configured to open the valve during a second cycle period, the method includes selecting a first mode or a second mode of engine operation, wherein in the first mode of engine operation the valve is opened during the compression stroke by the first cam and during the exhaust stroke by the second cam and in the second mode of engine operation opening of the valve is prevented during the compression stroke by the first cam.

Brief Description of the Drawings [0012] FIG. 1 is a cross sectional view of an exemplary engine configured to produce power.

[0013] FIG. 2 illustrates a cross-sectional view of an internal combustion engine showing the valve apparatus in accordance with an embodiment of the present disclosure.

[0014] FIG. 3 illustrates a cross-sectional view of an internal combustion engine showing the valve apparatus in accordance with an alternate embodiment of the present disclosure.

[0015] FIG. 4 is a diagrammatic illustration of the valve apparatus for the internal combustion in accordance with an embodiment of the present disclosure.

[0016] FIG. 5 is a diagrammatic illustration of the valve apparatus for the internal combustion in accordance with an alternate embodiment of the present disclosure.

[0017] FIG. 6 depicts a method of opening a valve according to an embodiment of the present invention.

Detailed Description [0018] Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0019] The present disclosure relates to a valve apparatus for improving the combustion process and avoiding self-ignition. FIG. 1 illustrates an exemplary engine 100 configured to power any vehicle. The engine 100 may be any engine running on solid, liquid or gaseous fuel, used for various purposes such as a power generation, a marine vessel, an automobile, a construction machine, any transportation vehicle and the like. In an embodiment, the engine 100 may be an internal combustion engine running on a hydrocarbon fuel.

[0020] Referring to FIG. 1, FIG. 2 and FIG. 3, an embodiment the engine 100 includes a cylinder head 102 and a cylinder block 104. The cylinder head 102, the cylinder block 104 and a piston 106 define a combustion chamber 108. In an alternate embodiment, the internal combustion engine 100 may have a plurality of combustion chambers 108. The combustion chamber 108 is configured to receive air-fuel mixture i.e. charge. The charge is burnt and the piston 106 is configured to transmit the driving force created by the burning charge to an output shaft 112. In the embodiment illustrated, the output shaft 112 is the crankshaft of the engine 100.

[0021] An ignition plug 110 is disposed at least partially in the combustion chamber 108. The ignition plug 110 may be connected with the cylinder head 102 by a threaded connection or other methods known in the art. The ignition plug 110 may be a typical J-gap spark plug, a spark plug with a pre-chamber, rail plug, extended electrode, or laser plug or any other type of spark plug known in the art.

[0022] As shown in FIG. 1, the cylinder head 102 defines one or more valve openings 114 for receiving a valve. An intake valve 124 and an exhaust valve 126 are disposed at least partially in the valve openings 114 of an intake port 120 and an exhaust port 122 respectively. The intake valve 124 and/or the exhaust valve 126 may have a spring or an elastic element 128. The spring element 128 is configured to bias the associated intake valve 124/exhaust valve 126 to its closed position. In various other embodiments, the spring element 128 may be any other type of biasing mechanism that can be used to bias the intake valve 124/exhaust valve 126 to its closed position.

[0023] A fuel introducing system 116 may be coupled to the intake valve 124, as shown in FIG. 1. The fuel introducing system 116 is configured to supply charge i.e. fuel or air-fuel mixture to the intake valve 124. The fuel introducing system 116 may include a conduit connecting a fuel injection system to the intake valve 124. In various other embodiments, the fuel introducing system 116 may be any system such as a direct injection system, a carburetor or any other fuel injection system known in the art.

[0024] The intake valve 124 is configured to supply the charge received from the fuel introducing system 116 into the combustion chamber 108. When the intake valve 124 is in an open position, the intake port 120 is in fluid communication with the combustion chamber 108 and the charge and/or fuel and/or air may be introduced into the combustion chamber 108. The opening of the intake valve 124 leads to the spring element 128 developing a restoring force to restore the intake valve 124 to its closed position. The restoring force of the spring element 128 brings the intake valve 124 to its closed position.

[0025] The exhaust valve 126 is configured to facilitate discharge of the combustion products from the combustion chamber 108. When the exhaust valve 126 is in an open position, the exhaust port 122 is in fluid communication with the combustion chamber 108 and exhaust/combusted gases may advance from the combustion chamber 108 and into the exhaust port 122. The opening of the exhaust valve 126 leads to the spring element 128 developing a restoring force to restore the exhaust valve 126 into its closed position. The restoring force of the spring element 128 brings the exhaust valve 126 to its closed position.

[0026] A valve apparatus 130 is provided for the engine 100, as shown in FIG. 2-5. The valve apparatus 130 is configured to control opening and closing of a valve of the engine 100. In the embodiment illustrated, the valve apparatus 130 is configured to open the exhaust valve 126 during at least one cycle period of the engine 100. The valve apparatus 130 may be mounted on the engine 100. In an alternate embodiment, the valve apparatus 130 may be mounted at any other location on the engine 100. The valve apparatus 130 comprises a camshaft 132 and a controller 134.

[0027] The camshaft 132 has a first cam 136 and a second cam 138. The first cam 136 is configured to open the exhaust valve 126 during a first cycle period of the engine 100 and the second cam 138 is configured to open the exhaust valve 126 during a second cycle period of the engine 100. In the embodiment illustrated, the second cam 138 height ‘c’ is larger than the first cam 136 height ‘1’, as shown in FIG. 2, FIG. 4 and FIG. 5. Further, in the embodiment illustrated, the first cycle period is during the compression stroke of the engine 100 and the second cycle period is during the exhaust stroke of the engine 100.

[0028] The controller 134 may be coupled to the camshaft 132, as shown in FIG. 2. The controller 134 is configured to permit opening of the exhaust valve 126 during at least one cycle period. The controller 134 has a first mode of operation and a second mode of operation. In the first mode of operation the controller 134 is configured to permit opening of the exhaust valve 126 by both the first cam 136 and the second cam 138. In the second mode of operation the controller 134 is configured to permit opening of the exhaust valve 126 by only the second cam 138. Thus, the controller 134 prevents opening of the exhaust valve 126 by the first cam 136 in the second mode of operation. In the embodiment illustrated, the controller 134 is a hydraulic cylinder having fluid disposed within. In the embodiment illustrated in FIG. 4 and FIG. 5, the maximal length ‘d’ of the hydraulic cylinder 134 occupied by the fluid 172 is greater than the height of the first cam ‘1’. Further, in the embodiment illustrated, the length ‘d’ of the hydraulic cylinder 134 occupied by the fluid 172 is greater than the height of the second cam ‘c\ [0029] Height ‘c’ and T are defined as the radial distances from a top of the cam to a minimal radius of the cam and/or to a radius of the cam. The height ‘1’ of the first cam 136 is such that in the second mode of operation of the controller, the motion caused by the first cam 136 can be absorbed or dissipated by the fluid present in the hydraulic cylinder 134 and no motion is transmitted to the exhaust valve 126. Further, the height ‘c’ of the second cam 138 is such that the motion transmitted by the second cam 138 is capable of flushing out the entire fluid 172 present in the hydraulic cylinder and opening the exhaust valve 126.

[0030] In the embodiment illustrated, the hydraulic cylinder 134 is in fluid communication with a fluid delivery system 170 present for the engine 100, as shown in FIG. 4 and FIG. 5. The fluid delivery system 170 may be any system present in the engine 100 such as a lubrication system, a coolant system, a water tank, a fluid pump or any other system known in the art. The fluid delivery system 170 may be configured to supply fluid such as engine oil, lubrication oil, coolant, water or any other fluids known in the art.

[0031] In the embodiment illustrated, the valve apparatus 130 further comprises a control element 140, as shown in FIG. 4 and FIG. 5. The control element 140 is coupled to the controller 134. The control element 140 may be configured to actuate either the first mode of operation or a second mode of operation for the controller 134. In the embodiment illustrated the control element 140 may be a valve configured to prevent flow of fluid 172 from the controller 134 to the fluid delivery system 170 and actuate the first mode of operation. Further, the control element 140 may place the controller 134 in the second mode of operation in which fluid is allowed to flow out from the controller 134 to the fluid delivery system 170.

[0032] When the control element 140 actuates the first mode of operation of the hydraulic cylinder 134, first cam 136 and the second cam 138 are unable to flush the fluid 172 out of the hydraulic cylinder 134. Since the fluid 172 in the hydraulic cylinder 134 is a at least partially incompressible liquid the motion caused by the first cam 136 and the second cam 138 is transmitted to the exhaust valve 126 causing it to open during a first cycle period and the second cycle period respectively.

[0033] When the control element 140 actuates the second mode of operation of the hydraulic cylinder 134, first cam 136 flushes the fluid 172 out of the hydraulic cylinder 134. The length ‘1’ of the first cam 136 is such that the motion caused by it is utilized to flush fluid 172 out of the hydraulic cylinder 134 thereby absorbing the motion caused by the first cam 136. Thus, in the second mode of operation opening of the exhaust valve 126 by the first cam 136 is prevented.

[0034] Further, as mentioned above, the length ‘c’ of the second cam 138 is configured to flush out the entire fluid 172 present in the controller 134 and open the exhaust valve 126. Thus, in the second mode of operation, the second cam 138 opens the exhaust valve 126.

[0035] In various other embodiments, the controller 134 may be any other structure, such as a lockable spring, which is configured to permit opening of the exhaust valve 126 during at least one cycle. In an embodiment, the controller 134 and the camshaft 132 may be coupled using a bolt and nut assembly. Alternatively, the controller 134 and the camshaft 132 may be coupled by welding, soldering, or other methods known in the art.

[0036] In the embodiment illustrated in FIG. 2, the valve apparatus 130 may also include a spring plate 142. One end of the spring plate 142 is coupled to the controller 134 and the opposite end of the spring plate 142 may be coupled to the spring element 128. The spring plate 142 is configured to transmit the motion received by the controller 134 to open the exhaust valve 126.

[0037] In an embodiment, the valve apparatus 130 may further have a cam follower 144, a push rod 146 and a rocker arm 148 , as shown in FIG. 3, FIG. 4 and FIG. 5. The cam follower 144, the push rod 146 and the rocker arm 148 may be mounted on the intake valve 124 and/or the exhaust valve 126 and may be configured to transmit motion from the camshaft 132 to open the associated valve during engine 100 operation.

[0038] The cam follower 144 defines a first follower end 150 and a second follower end 152. The first follower end 150 of the cam follower 144 may be fixated relative to the cylinder block 104, as shown in FIG. 3. Further, the second follower end 152 of the cam follower 144 may be coupled to the controller 134, as shown in FIG. 3. Further, a cam roller 154 may be disposed on the cam follower 144 and is configured to engage with the camshaft 132 and transfer motion received from the camshaft 132 to the controller 134.

[0039] In the embodiment illustrated as illustrated in FIG. 3, FIG. 4 and FIG. 5, the controller 134 defines a first end 156 and a second end 158. The first end 156 of the controller 134 is coupled to the cam follower 144 and the second end 158 of the controller 134 is coupled to the push rod 146. The controller 134 is configured to transmit motion from the camshaft 132 to the push rod 146.

[0040] The push rod 146 may further be coupled to the rocker arm 148 and may be configured to pivot the rocker arm 148 when the controller 134 transmits motion from the camshaft 132 to the push rod 146.

[0041] The rocker arm 148 defines a first rocker end 160 and a second rocker end 162. The first rocker end 160 of the rocker arm 148 is coupled to the spring element 128 and the second rocker end 162 of the rocker arm 148 is coupled to the push rod 146. The rocker arm 148 is configured to transmit motion received by the push rod 146 to the associated intake valve 124/ exhaust valve 126.

Further, in the process of the transmitting motion between the push rod 146 and the intake valve 124/exhaust valve 126, the rocker arm 148 pivots, opens the associated intake valve 124/exhaust valve 126. In the process of opening the intake valve 124/exhaust valve 126, the spring element 128 compresses and develops a restoring force to restore the intake valve 124/exhaust valve 126 in its closed position.. It may be contemplated that the components of the valve apparatus 130, the cam follower 144, the push rod 146 and the rocker arm 148 may be coupled using a nut and bolt assembly, welding, soldering or other methods known in the art.

[0042] In an embodiment, the valve apparatus 130 may further have an electronic control unit (ECU) 164 as shown in FIG. 4 and FIG. 5. The electronic control unit ECU 164 may be a digital computer that may include a central processing unit (CPU), a read-only-memory (ROM), a random access memory (RAM), and an output interface. The ECU 164 receives input signals from various sensors (not illustrated) that represent various engine 100 operating conditions.

[0043] For example, an accelerator opening signal from an accelerator opening sensor may detect engine load, a water temperature signal from a water temperature sensor may detect engine temperature, and a crank angle signal from a crank angle sensor may detect the angular position of a crankshaft (not shown), and which may be used by the ECU 164 to calculate engine rotation speed (e.g., number of revolutions per minute of the engine 100). In response to the input signals, the ECU 164 controls various parameters that govern operation of the engine 100. For example, the ECU 164 may control the amount and timing of the charge injected by the intake valve 124, the ignition timing of the ignition plug 110. Further, ECU 164 may also monitor and calculate the time for which the intake valve 124 opens.

[0044] The ECU 164 may also monitor the variation in pressure and temperature inside at least one combustion chamber 108 during engine 100 operation. Further, the ECU 164 monitors the variation in the injection timings and the amount of fuel injected by the fuel introducing system 116 the through the intake valve 124. In an alternate embodiment, the ECU 164 may monitor and store the amount of charge being introduced into the combustion chamber 108 by any other fuel introducing means known in the art. In an embodiment, based on these variations in the pressure, temperature and the variation in the amount of charge introduced into the combustion chambers 108, the ECU 164 passes on a signal to the control element 140 to actuated either the first mode of operation or the second mode of operation for the controller 134 during engine 100 operation.

[0045] In the embodiment illustrated, the ECU 164 actuates the first mode of operation for the controller 134 when the pressure inside the combustion chamber 108 exceeds a certain threshold value. In an alternate embodiment, the ECU 164 may actuate the first mode of operation for the controller 134 when a sudden rise in combustion pressure is predicted by the ECU 164. Further, the ECU 164 actuates the second mode of operation for the controller 134 when the pressure inside the combustion chamber 108 is below the threshold value. In the embodiment illustrated, the ECU 164 may have unique threshold values for each RPM of the engine 100.

[0046] The working of the engine 100 along with the valve apparatus 130 and the ECU 164 will now be explained in detail with reference to FIG. 2-5 . During normal engine 100 operation, a cycle takes place and converts the chemical energy of the charge to give mechanical energy. For example, the cycle may comprise of four cycle periods i.e. an intake stroke, a compression stroke, a power stroke and an exhaust stroke. Firstly an intake stroke takes place during the cycle. During this stroke the intake valve 124 is opened by an intake cam (not shown) while the exhaust valve 126 is in a closed position. Further, during this stroke the piston 106 starts moving from a top dead center to a bottom dead center. Due to the downward motion of the piston 106 vacuum pressure is created which pulls some charge from the intake valve 124 into the combustion chamber 108.

[0047] When the piston 106 reaches its bottom dead center the compression stroke is initiated. During the compression stroke the intake valve 124 is in its closed position. Further, during the compression stroke, the piston 106 starts moving from the bottom dead center to the top dead center to compress the charge within the combustion chamber 108 thereby preparing it for ignition during the power stroke. Simultaneously, the ECU 164 runs various algorithms stored in its memory on the data received from the sensors disposed on the intake valve 124 and the fuel introducing system 116 and predicts whether the pressure in the combustion chamber 108 would exceed a certain threshold value. In the embodiment illustrated, the ECU 164 monitors the amount of charge introduced by the intake valve 124 during the intake stroke. In various other embodiments, the ECU 164 may monitor other parameters of the engine and predict the temperature and pressure within the combustion chamber 108. Based on the results of the algorithms, the ECU 164 predicts whether the pressure and temperature inside the combustion chamber 108 would be within permissible limit for example lesser or equal to a threshold value or higher than the permissible limit.

[0048] If the ECU 164 predicts that the temperature and pressure inside the combustion chamber 108 are within permissible limits a signal is passed on to the control element 140 to actuate the second mode of operation for the controller 134. Since the controller 134 is in its second mode of operation it prevents opening of the exhaust valve 126 by the first cam 136 during the compression stroke. Thus, both the intake valve 124 and exhaust valve 126 are closed during the compression stroke during the second mode of operation for the controller 134.

[0049] However, if the ECU 164 predicts that pressure inside the combustion chamber 108 exceeds a certain threshold value, a signal is passed on to the control element 140 to actuate the first mode of operation for the controller 134. The controller 134 in its first mode of operation permits partially opening the exhaust valve 126 during the compression stroke using the first cam 136. Thus, when the piston 106 moves from the bottom dead center to the top dead center a portion of the charge is allowed to escape through the exhaust valve 126. This causes a reduction in the pressure and temperature within the combustion chamber 108. Thus, in the first mode of operation for the controller 134 the intake valve 124 remains in a closed position while the exhaust valve 126 is in an open or partially open position during compression stroke.

[0050] When the piston 106 reaches the top dead center after completing the compression stroke a power stroke is initiated. The power stroke marks the start of the second revolution of the cycle. At this point the output shaft 112 has completed a full 360 degree revolution. During this stroke both the intake valve 124 and the exhaust valve 126 are in the closed position. Further, during this stroke the compressed charge is ignited by an ignition plug 110 in case the engine 100 is a gasoline engine. In an alternate embodiment, the compressed charge may be ignited by the heat generated by the high compression pressure generated in case the engine 100 is a diesel engines. Igniting the charge creates an explosion within the combustion chamber 108 and forcefully moves the piston 106 from the top dead center to the bottom dead center. This stroke produces mechanical work from the engine 100 to turn the output shaft 112.

[0051] Finally the exhaust stroke is initiated. During this stroke the piston 106 starts returning from the bottom dead center to the top dead center. The exhaust valve 126 is always in its open position during the exhaust stroke as the controller 134 is configured to permit opening the exhaust valve 126 by the second cam 138 during both the first mode of operation and the second mode of operation for the controller 134. The upward motion of the piston 106 along with the exhaust valve 126 in its open position, during the exhaust stroke, facilitates the products of combustion (combusted charge) to escape the combustion chamber 108.

[0052] The working of the engine 100 wherein the valve apparatus 130 has the hydraulic cylinder as the controller 134 will now be explained in detail with reference to FIG. 4. The hydraulic cylinder 134 is disposed between the cam follower 144 and the push rod 146. In an alternate embodiment, the push rod 146 may have a first rod part 166 and a second rod part 168 as shown in FIG. 5. The hydraulic cylinder 134 may be disposed between the first rod part 166 and the second rod part 168, as shown in FIG. 5. The hydraulic cylinder 134 is configured to receive fluid from the fluid delivery system 170. In the embodiment illustrated, the control element 140 may be communicably coupled to the hydraulic cylinder 134.

[0053] During engine 100 operation, the camshaft 132 is configured to rotate and transmit motion via the first cam 136 and the second cam 138 to the hydraulic cylinder 134. When the camshaft 132 rotates, the first cam 136 comes in contact with the cam follower 144 and an upward motion is transmitted to the cam follower 144. The cam follower 144 transmits the upward motion to the hydraulic cylinder 134.

[0054] When the first mode of operation is actuated for the hydraulic cylinder 134, the hydraulic cylinder 134 is in a locked position. In the locked position, the hydraulic cylinder 134 does not permit fluid 172 to flow out of the hydraulic cylinder 134. Since the fluid 172 present in the hydraulic cylinder 134 is at least a partially incompressible fluid, the upward motion received by the hydraulic cylinder 134 from the cam follower 144 and the first rod part 166 is transmitted to the second rod part 168. The push rod 146 pivots the rocker arm 148 and opens the exhaust valve 126 during the compression stroke. Similarly, the exhaust valve 126 is opened by the second cam 138 during the exhaust stroke.

[0055] In the second mode of operation of the hydraulic cylinder 134 fluid is allowed to flow out of the hydraulic cylinder 134. When the upward motion is received by the hydraulic cylinder 134 from the first cam 136, a compressive force acts on the hydraulic cylinder 134. This compressive force developed pushes the fluid 172 out of the hydraulic cylinder 134. Since length ‘1’ of the first cam 136 is lesser than the maximal length of the fluid ‘d’ of the hydraulic cylinder 134 occupied by the fluid 173 the upward motion of the cam follower 144 caused by the first cam 136 is utilized to flush fluid out of the hydraulic cylinder 134. Thus, the hydraulic cylinder 134 prevents the first cam 136 to open the exhaust valve 126 during the compression stroke in the second mode of operation of the hydraulic cylinder 134.

[0056] However, in the second mode of operation the hydraulic cylinder 134 is configured to open the exhaust valve 126 by the second cam 138. The camshaft 132 rotates and the second cam 138 comes in contact with the cam follower 144. This creates an upward motion which is transmitted to the cam follower 144. The cam follower 144 transmits the upward motion to the hydraulic cylinder 134. The upward motion received by the hydraulic cylinder 134 from the second cam 138 creates a compressive force. This compressive force developed pushes the fluid out of the hydraulic cylinder 134. After flushing fluid 172 out of the hydraulic cylinder 134, the second cam 138 transmits upward motion to the push rod 146 because ‘c’ (length of second cam) is greater than ‘d’ (length of fluid present in the hydraulic cylinder 134). The upward motion of the push rod 146 pivots the rocker arm 148 and opens the exhaust valve 126 during the exhaust stroke. Thus, the hydraulic cylinder 134 allows the second cam 138 to open the exhaust valve 126 in the second mode of operation.

Industrial Applicability [0057] In typical internal combustion engines ignition of the air-fuel mixture within the combustion chamber produces torque as the mechanical output. The spark generated by an ignition plug ignites the air-fuel mixture within the combustion chamber. However, during operation of the engine, excess fuel may be introduced in the combustion chamber due to failure of the fuel injection system. As a result the air-fuel ratio changes from a leaner to a richer mixture. This change in the air fuel ratio may increase the pressure in the combustion chamber which may cause sudden self-ignition of the air-fuel mixture. The high pressure peaks caused by sudden self-ignition accompanied by the high combustion velocity of the air-fuel mixture may cause damage to the cylinders, pistons, and valves, which is undesirable.

[0058] In an aspect of the present disclosure, a valve apparatus 130 is disclosed. The valve apparatus 130 may be provided for the intake valve 124 and/or the exhaust valve 126 of the engine 100, as shown in FIG. 2 and FIG. 3. The valve apparatus 130 has a camshaft 132 having a first cam 136 to open the exhaust valve 126 during the first cycle period and a second cam 138 to open the exhaust valve 126 during the second cycle period. The valve apparatus 130 further comprises a controller 134 having a first mode of operation and a second mode of operation.

[0059] An ECU 164 is communicably coupled to a control element 140, as shown in FIG. 4 and FIG. 5. The ECU 164 receives data from the sensors disposed on the intake valve 124 and the fuel introducing system 116 and predicts whether the pressure in the combustion chamber 108 would exceed a certain threshold value. If the ECU 164 predicts that pressure inside the combustion chamber 108 exceeds a certain threshold value, a signal is passed on to the control element 140 to actuate the first mode of operation for the controller 134. Thus, the controller 134 permits opening the exhaust valve 126 during the compression stroke when the first mode of operation is actuated for the controller 134.

[0060] Opening of the exhaust valve 126 during the compression stroke allows some of the charge injected by the intake valve 124 to escape the combustion chamber 108. This ensures that pressure in the combustion chamber 108 is within permissible limits. Further, allowing the extra charge to escape prevents a sudden rise in the pressure and temperature within the combustion chamber 108. This helps avoid knocking due to auto ignition. Accordingly, damage to the piston 106, the cylinder block 104 and the output shaft 112 is also prevented.

[0061] In yet another aspect of the present disclosure, a cam follower 144, a push rod 146 and a rocker arm 148 may also be provided for the valve apparatus 130. The combination of the cam follower 144, the push rod 146 and the rocker arm 148 acts as an intermediary structure to transmit motion from the camshaft 132 to open the exhaust valve 126 during engine 100 operation.

[0062] In another aspect of the present disclosure, a method 600 of controlling opening and closing the exhaust valve 126 of the engine 100 is disclosed. The method 600 of controlling opening and closing the exhaust valve 126 will now be explained with reference to FIG. 6. Selecting either the first mode of engine operation or the second mode of engine operation (Step 602). In the first mode of engine operation the exhaust valve 126 is opened during the first cycle period by the first cam 136. Further, in the first mode of engine operation the exhaust valve 126 is opened during the second cycle period by the second cam 138. In the second mode of engine operation opening of the exhaust valve 126 is prevented by the first cam 136 during the first cycle period.

[0063] In yet another aspect of the present disclosure, the method 600 further comprises a detecting the pressure and temperature in at least one combustion chamber 108 of the engine 100. In yet another aspect of the present disclosure, the method 600 further comprises using a control element 140 to actuate either the first mode of engine operation or the second mode of engine operation for the controller 134.

[0064] While aspects of the present disclosure have seen particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

Claims

Claims What is claimed is:

1. A valve apparatus for controlling the opening and closing of a valve of an internal combustion engine, the valve apparatus comprising: a camshaft having a first cam configured to open the valve during a first cycle period of the internal combustion engine and a second cam configured to open the valve during a second cycle period of the internal combustion engine; and a controller having at least a first mode of operation and a second mode of operation; in the first mode of operation the controller configured to permit opening of the valve by the first cam and the second cam and in the second mode of operation the controller configured to prevent opening of the valve by the first cam.

2. The valve apparatus of one of the claim 1, wherein the controller is a hydraulic cylinder.

3. The valve apparatus of one of the claims 1 to 2 wherein the controller has a first end and a second end, the first end is coupled to the cam follower and the second end is coupled to a push rod.

4. The valve apparatus of claim 3 wherein the push rod is coupled to a rocker arm.

5. The valve apparatus as claimed in any preceding claim further comprising an electronic control unit configured to monitor pressure and temperature in at least one combustion chamber of the internal combustion engine.

6. The valve apparatus as claimed in any preceding claim wherein the length of the second cam is greater than the length of the first cam.

7. The valve apparatus as claimed in any preceding claim, wherein the length of the second cam is greater than the length of the controller.

8. The valve apparatus as claimed in any preceding claim, wherein the first cycle period is during a compression stroke.

9. The valve apparatus as claimed in any preceding claim, wherein the second cycle period is during an exhaust stroke.

10. An engine system comprising: a valve; a camshaft having a first cam configured to open the valve during a first cycle period of the internal combustion engine and a second cam configured to open the valve during a second cycle period of the internal combustion engine; and a controller having a first mode of operation and a second mode of operation; in the first mode of operation the controller configured to permit opening of the valve by the first cam and the second cam and in the second mode of operation the controller configured to prevent opening of the valve by the first cam.

11. The engine system of claim 10, wherein the controller is a hydraulic cylinder.

12. The engine system of one of the claims 10 and 11 wherein the controller has a first end and a second end, the first end coupled to the cam follower and the second end coupled to a push rod.

13. The engine system of claim 12 wherein the push rod is coupled to a rocker arm.

14. The engine system of one of the claims 10 to 13 further comprising a control unit configured to monitor pressure and temperature in at least one combustion chamber of the engine system.

15. The engine system of one of the claims 10 to 14 wherein the length of the second cam is greater than the length of the first cam.

16. The engine system of one of the claims 10 to 15, wherein the length of the second cam is greater than the length of the controller.

17. The engine system of claim of one of the claims 10 to 16, wherein the first cycle period is during a compression stroke and the second cycle period is during the exhaust stroke.

18. A method of controlling opening and closing a valve of an engine, the engine comprising a camshaft having a first cam configured to open the valve during a first cycle period and a second cam configured to open the valve during a second cycle period, the method comprising: selecting a first mode or a second mode of engine operation, wherein in the first mode of engine operation opening the valve during the first cycle period by the first cam and during the second cycle period by the second cam and in the second mode of engine operation preventing opening of the valve during the first cycle period by the first cam.

19. The method of claim 18 further comprising detecting pressure and temperature in at least one combustion chamber of the internal combustion engine.

20. The method of one of the claims 18-19 further comprising actuating a control element to select the first mode or the second mode of engine operation.