Patent Publication Number: US-2015082781-A1

Title: Pneumatic system for engines

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to a system to rotate a crankshaft of an engine. More specifically, the present disclosure relates to a pneumatic system to rotate the crankshaft. 
     BACKGROUND 
     Various machines, such as electric locomotives, employ an engine to produce power to run the machine. These engines may often require service and/or repair. Many service and/or repair procedures require the rotation of a crankshaft of the engine. By this means, the crankshaft may be deployed in orientations that enable access to associated components of the engine, for example, a piston. This procedure is generally termed as “barring” and/or “roll-over” of the crankshaft. Barring and/or roll-over of the crankshaft are generally performed by use of dedicated mechanical tools, which couple the crankshaft of the engine and facilitate manual rotation of the crankshaft. 
     Modern machines have space constraints because of closed packing arrangements of various adjoining components. Therefore, it becomes considerably burdensome to attach mechanical tools to the crankshaft. In instances where a generator is relatively closely coupled to the engine, such as in locomotive engines, space required to mount such mechanical tools is negligible. As a result, components of the machine are generally disassembled from the machine (or engine) before an engagement of the crankshaft is performed. This increases service time and effort, and has a proportional impact on the costs involved. 
     U.S. Pat. No. 5,997,260 discloses an engine barring adapter attached/mounted on a shaft of an air compressor. The shaft of the air compressor includes an air compressor gear engaged with a crankshaft gear of the crankshaft. The engine barring adapter is mounted on the shaft of the air compressor and includes a tool that engages the end to which the mechanical tool may be mounted to rotate the crankshaft. Although, this reference provides a system to rotate the crankshaft of the engine, no solution is provided to rotate the crankshaft of the engine without the use of mechanical tools. 
     SUMMARY OF THE INVENTION 
     One aspect of the present disclosure is directed to a method to rotate a crankshaft of an engine via a pneumatic system. The engine has a plurality of engine cylinders. Each of the plurality of engine cylinders includes a piston and a connecting rod, which connects the piston to the crankshaft. The pneumatic system includes an air compressor and a plurality of valves. The air compressor is in fluid communication with the plurality of engine cylinders. The valves are correspondingly disposed between the air compressor and the engine cylinders. The method includes monitoring an angular orientation of the crankshaft. Based on the angular orientation of the crankshaft, a position of the piston within the engine cylinders may be determined. Thereafter, an engine cylinder amongst the engine cylinders that has the piston in one of a power stroke or a compression stroke is selected. Next, a valve that corresponds to the engine cylinder is activated. Upon activation of the valve, compressed air is supplied to the engine cylinder by the air compressor. Once the piston of the engine cylinder attains completion of one of the power strokes or the compression strokes, the valve is deactivated. Each of the stages of activation, supply, and deactivation, are sequentially repeated for each of the engine cylinders, based on a predetermined firing order of the engine. 
     Another aspect of the present disclosure is directed to a pneumatic system to rotate a crankshaft of an engine. The engine has a plurality of engine cylinders. Each of the plurality of engine cylinders includes a piston and a connecting rod attached between the piston and the crankshaft. The pneumatic system includes an air compressor and a plurality of valves. The air compressor is in fluid communication with the plurality of engine cylinders. The valves are disposed between the air compressor and the engine cylinders. Each valve may correspond to at least one of the engine cylinders. The valves may be actuated in a predefined firing order based on an angular orientation of the crankshaft. Further, the actuation of the valves facilitates a supply of compressed air from the air compressor to a corresponding engine cylinder, thereby rotating the crankshaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exemplary block diagram of an engine that illustrates a pneumatic system to rotate a crankshaft of the engine, in accordance with the concepts of the present disclosure; and 
         FIG. 2  is a flowchart that depicts an exemplary method of the pneumatic system of  FIG. 1 , in accordance with the concepts of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , there is shown a pneumatic system  100  to rotate various components of an engine  102 . The engine  102 , may be configured in a machine (not shown) that embodies one of a locomotive, a construction machine, a forest machine, a marine machine, and/or any other similar machine. Applicability to stationary machines, such as power generation systems and other electric power generating machines, may also be envisioned. Further, the concepts of the present disclosure may also be applicable to any machine that utilizes internal combustion engines for varied power generation requirements. 
     The engine  102  may be one of a spark ignition and/or a compression ignition type. Other engine types may also be contemplated. In an embodiment, a configuration of the engine  102  may constitute one of an ‘In-line layout’ or a ‘V-layout’. The engine  102  may include multiple engine cylinders  104  and a crankshaft  106 . 
     In the current embodiment of disclosure, the engine cylinders  104  are exemplified as six in number. The engine cylinders  104  include closed chambers in which a fuel is delivered to be combusted. By this means, power is produced to operate the engine  102 . Each of the engine cylinders  104  includes a piston  108  and a connecting rod  110  that connects the piston  108  to the crankshaft  106 . Each piston  108  may be positioned in one of an intake stroke, a compression stroke, a power stroke, and an exhaust stroke. Moreover, it may be noted that a translational movement of the piston  108  corresponds to a rotational movement of the crankshaft  106 . The crankshaft  106  may be suitably connected to various other components of the engine  102 , for example a camshaft, to impart a proportional movement. 
     During service and/or repairs, situations may arise that postulate the physical accessibility of one or more of the above noted components. In preferred implementations, this would involve a controlled rotation (barring and/or roll-over) of the crankshaft  106 . This may be attained via the pneumatic system  100 , as described below. 
     The pneumatic system  100  may be provided to bar and/or roll over the crankshaft  106 , when installed with the engine  102 . More particularly, the pneumatic system  100  is adapted to supply compressed air to at least one of the engine cylinders  104  that has the piston  108  in one of the compression stroke and/or the power stroke. Notably, a supply of compressed air to the engine cylinder  104  that has the piston  108  in its power stroke corresponds to rotation of the crankshaft  106  in its normal operating direction. Conversely, a supply of compressed air to the engine cylinder  104  that has the piston  108  in its compression stroke corresponds to rotation of the crankshaft  106  in a direction opposite to the normal operating direction. Moreover, the pneumatic system  100  may supply compressed air to the six engine cylinders  104  in a sequential manner that follows an engine firing order for continuous rotation of the crankshaft  106 . A sequential supply of compressed air to the all the six engine cylinders  104  oriented in power stroke results in one complete rotation of the crankshaft  106  in the normal operating direction. Also, a sequential supply of compressed air to the all the six engine cylinders  104  oriented in compression stroke results in one complete rotation of the crankshaft  106  in a direction opposite to the normal operating direction. Although, the exemplary embodiment discloses an idea of supplying the compressed air to one of the multi-cylinders of the engine  102 , other combinations, such as compressed air simultaneously supplied to multi-cylinders, in which the pistons  108  move in the same translational direction, to achieve easier and quicker rotation of the crankshaft  106 , may also be contemplated. 
     The pneumatic system  100  includes an air compressor  112 , a main valve  113 , multiple valves  114 , an engine pointer  116 , and a selector switch  118 . Fluid communication lines  120 ,  121 ,  123  may extend from the air compressor  112  to connect to each of the engine cylinders  104 , via the main valve  113  and the valves  114 . 
     The air compressor  112  may be a device that draws air from an external environment, compresses the drawn air, and delivers the air at high pressure as an output, when required. The air compressor  112  may be at least one of a rotary compressor, a screw compressor, a reciprocating compressor, a centrifugal compressor, and/or similar devices. The output of air compressor  112 , constitute a delivery of compressed air to each of the engine cylinders  104 . 
     The main valve  113  may be a manually operated normally closed valve that controls the supply of compressed air from the air compressor  112  to other components of the pneumatic system  100 . The main valve  113  is disposed between the air compressor  112  and the valves  114  and is adapted to operate in an open position and a normally closed position. In the open position, the main valve  113  allows a supply of compressed air from the air compressor  112  to the valves  114 . In the normally closed position, the main valve  113  restricts the supply of compressed air from the air compressor  112  to the valves  114 . 
     The valves  114  may be solenoid-operated disposed between the main valve  113  and the engine cylinders  104 . The valves  114  facilitate a controlled delivery of compressed air from the air compressor  112  to the engine cylinders  104  through the main valve  113 . Each of the valves  114  may respectively correspond to each of the engine cylinders  104 . Accordingly, there may be six valves  114  to correspond to each of the engine cylinders  104 , as shown in  FIG. 1 . The valves  114  may operate in one of an extended position and a retracted position. When in the extended position, the valves  114  facilitate a supply of compressed air from the air compressor  112  to the respective engine cylinders  104 . When in the retracted position, the valves  114  facilitate vent out of the compressed air already present in the engine cylinders  104 , as well as additional air displaced by the movement of the piston  108  through subsequent crankshaft rotation, to the external environment. The high pressure air from the downstream of valve  114 , exerts a pressure on the corresponding piston  108  of the engine cylinder  104 , causing the piston  108  to move from its top dead center (TDC) to towards the bottom dead center (BDC). A controlled rotational movement of the crankshaft  106  may be achieved by this configuration. 
     In an embodiment, a singular valve may be selectively connected to each of the engine cylinders  104  and may be configured to perform the function of each of the valves  114 . In such cases, known systems may be positioned proximal to and in connection with the affiliated fluid communication line  120 . This connection selectively channels and/or varies air delivery into each of the engine cylinders  104 . 
     The engine pointer  116  is connected to the crankshaft  106  to denote the angular orientation of the crankshaft  106 . The engine pointer  116  may be at least one of an analog-based device or a digital-based device that may continuously monitor the angular orientation of the crankshaft  106 . Known connecters may be disposed to have the engine pointer  116  operably linked with the crankshaft  106  for related angular measurements. Threaded, luer-lock, snap-fit, keyway joints, and/or similar connections are also contemplated, to establish such a link In an embodiment, the engine pointer  116  is connected to the engine&#39;s flywheel (not shown) or to other rotatable devices connected to the engine  102  that help determine the angular orientation of the crankshaft  106 . By monitoring the angular orientation of the crankshaft  106 , a corresponding position and state of the pistons  108  may be determined. 
     The selector switch  118 , is controllably connected to the valves  114  via cabled wires  122 . The selector switch  118  is adapted to selectively switch the valves  114  between the extended position and the retracted position. In the current embodiment, the selector switch  118  is electrically controllable to provide input to the valves  114  based on the angular orientation of the crankshaft  106 . The selector switch  118  may be manually controlled by an operator sitting in vicinity of the engine pointer  116 . In the manually controlled mode, the operator may observe the engine pointer  116 , determine the angular orientation of the crankshaft  106 , and correspondingly actuate the valves  114 . In an exemplary embodiment, the selector switch  118  is operably connected to the engine pointer  116 , to automatically receive input from the engine pointer  116 . More particularly, the engine pointer  116  provides data that corresponds to the angular orientation of the crankshaft  106  and accordingly the selector switch  118  adjusts the valves  114  based on the data received. 
     Referring to  FIG. 2 , an exemplary method in connection with the pneumatic system  100  set out above is provided. The method may be manually operated and is described by means of a flowchart  200 , as shown. 
     The method initiates at step  202 . At step  202 , the engine pointer  116  monitors the angular orientation of the crankshaft  106 . The method proceeds to step  204 . 
     At step  204 , a position of the piston  108  within the engine cylinders  104  is determined based on the monitored angular orientation of the crankshaft  106 . The method proceeds to step  206 . 
     At step  206 , an operator may select an engine cylinder  104  amongst the engine cylinders  104  that has the piston  108  in one of a power stroke or a compression stroke. Additionally, the operator may activate the main valve  113  to open position to allow a supply of compressed air from the air compressor  112  to the valves  114 . The method proceeds to step  208 . 
     At step  208 , the operator may activate a valve  114  amongst the valves  114  that correspond to the selected engine cylinder  104  using the selector switch  118 . The activation may correspond to the extended position of the valve  114  from the retracted position. The method proceeds to step  210 . 
     At step  210 , the extended position of the valve  114  may facilitate a supply of compressed air from the air compressor  112  to the selected engine cylinder  104 . The method proceeds to step  212 . 
     At step  212 , the selector switch  118  may deactivate the valve  114 , and thereby, may halt a supply of compressed air into the selected engine cylinder  104 . At this stage, the piston  108 , within the selected engine cylinder  104 , which received the supply of the compressed air, may have reached the bottom dead center (BDC) of the engine cylinder  104 . The method proceeds to end step  214 . 
     At end step  214 , an operator may sequentially repeat the stages of activation, supply and deactivation (or steps  208 ,  210 , and  212 ) on the remainder of the engine cylinders  104  that are due to receive a compressed air supply and a corresponding service. This sequential repetition of the described stages may occur based on a predetermined firing order of the engine  102 . This facilitates continuous rotation of the crankshaft  106 . However, as the crankshaft  106  reaches a desired angular orientation, the operator may deactivate the main valve  113 , returning it to the normally closed position. In the normally closed position, the main valve  113  discontinues the supply of compressed air to the valves  114 , thereby restricting further movement of the crankshaft  106 . Hence, the crankshaft  106  is oriented and locked in the desired angular orientation. 
     INDUSTRIAL APPLICABILITY 
     Service and repair procedures may require an operator to access the components within the engine  102 . For example, an overhauling operation may require the piston  108  (and/or other affiliated components) to be removed, cleaned, and re-assembled. Given the firing order of the engine  102 , pistons  108  are generally variably oriented (or positioned) within the engine cylinders  104 . Accordingly, each piston  108  may require to be manipulated individually to attain suitable access. 
     In operation, an operator may lock the crankshaft  106  in one of a set position or orientation and connects the pneumatic system  100  with the engine  102 . It may be noted that the pneumatic system  100  may be connected to a slot provided within the engine  102  that connects the pneumatic system  100  to the engine cylinders  104 . The slot of the engine  102  may otherwise be covered and protected using a plug, when the pneumatic system  100  is not in use. 
     Furthermore, after connecting the pneumatic system  100  with the engine  102 , the operator may determine the angular orientation of the crankshaft  106  by observing the engine pointer  116  connected to the crankshaft  106 . Once the angular orientation of the crankshaft  106  is determined, the main valve  113  is actuated to its open position to allow flow of compressed air form the air compressor  112  to the valves  114 . Thereafter, depending upon the crankshaft&#39;s orientation, the operator may adjust the selector switch  118 , to actuate the valve  114  in the extended position that corresponds to the engine cylinder  104  that has the piston  108  in at least one of a compression stroke or a power stroke. Notably, in either of these strokes, the engine cylinder  104  may have the respective intake and exhaust valves in a closed state. Such actuation may facilitate the piston  108  to receive compressed air, which builds pressure that pushes the piston  108  towards the BDC of the engine cylinder  104 . A resulting angular movement of the crankshaft  106  is also executed. Thereafter, the valve  114  is retracted or deactivated to cut-off the supply of compressed air. In the retracted position, the valve  114  is open to the external environment, and facilitates bleed out of the compressed air as well as additional air displaced by the movement of the piston  108  through subsequent crankshaft rotation to the external environment. 
     Subsequently, the valve  114 , which corresponds to the engine cylinder  104  and lies next according to the engine firing order, may be actuated. Notably, the next piston  108  within the next engine cylinder  104  is also in one of the compression stroke or the power stroke. A forthcoming flow of compressed air pushes the next piston  108  to the BDC as well. This results in a further movement of the crankshaft  106 . Furthermore, it may be noted that while one of the valves  114  is actuated to be in extended position, remaining valves  114  are kept in the retracted position and vent out the compressed air earlier provided as well as additional air displaced by the movement of the piston  108  through subsequent crankshaft rotation to the external environment. In an exemplary embodiment, five valves  114  corresponding to the five engine cylinders  104  (non-active) are disposed in the retracted position while the sixth valve  114  corresponding to the sixth engine cylinder  104  (active) is disposed in the extended position. The sixth valve  114  allows supply of compressed air form the air compressor  112  to the sixth engine cylinder  104  (active). This facilitates rotation of the crankshaft  106  and correspondingly movement of the piston  108  of remaining five engine cylinders  104  (non-active). A corresponding movement of the piston  108  of remaining five engine cylinders  104  (non-active) facilitates entry and/or vent out of the displaced air to the external environment, while the remaining five valves  114  are in retracted position. 
     Similarly, each piston  108  may be subjected to the sequential flow of compressed air, according to the engine firing order. A service operation may be performed at other cylinder stations that are not currently connected to the pneumatic system  100 . Therefore, a sequential actuation of the valves  114  may allow the engine cylinders  104  to receive a sequential supply of compressed air, according to the set firing order of the engine  102 . A cycle may be complete when each of the pistons  108  has been subject to the flow of compressed air at least once. The cycle may be repeated, if required. Furthermore, once the crankshaft  106  reaches the desired angular orientation, the main valve  113  may be returned to the normally closed position. Return of the main valve  113  to the normally closed position restricts supply of compressed air form the air compressor  112  to the valves  114 . Therefore, no further rotation of the crankshaft  106  may occur. This facilitates locking of the crankshaft  106  to the desired position. 
     A crankshaft rotational output gained through the delivery of compressed air while the piston  108  is in a compression stroke may differ from when the piston  108  is in the power stroke. In further detail, when a supply of compressed air is facilitated into the engine cylinder  104  that has the piston  108  positioned in a power stroke, a first direction roll (rotation in a normal operating direction) of the crankshaft  106  is enabled. However, when the piston  108  is in a compression stroke state and is subject to a supply of compressed air, a reverse direction roll (rotation in the direction opposite to the normal operating direction) of the crankshaft  106  is enabled. Such a feature may be applicable when the piston  108  or components within any of the engine cylinders  104  require to be accessed repeatedly. 
     It should be understood that the above description is intended for illustrative purposes only and is not intended to limit the scope of the present disclosure in any way. Those skilled in the art will appreciate that other aspects of the disclosure may be obtained from a study of the drawings, the disclosure, and the appended claim.