Patent Application
20190032520
The present disclosure relates in general to valve trains in internal combustion engines. More particularly, the present disclosure relates to a guide assembly for valve trains that restricts a rotation of a valve lifter of the valve trains.
Generally, valve trains in internal combustion engines (referred also to as engines) employ a valve lifter to transmit motion from a rotating cam lobe to one or more valves of the engines. During engine operations, for example, a valve lifter translates along a longitudinal axis, converting a rotary motion of the cam lobe into a reciprocatory action of the one or more valves, thereby facilitating an opening and a closure of the one or more valves, for engine operation.
Although operations of a valve lifter are commonly limited to a transition along the longitudinal axis during translatory motions, in some circumstances, a valve lifter may also undesirably turn about the longitudinal axis. Because of such turning (or rotation), an alignment between one or more components of the valve train may be altered. For example, a roller of the valve lifter, which may interact with the cam lobe, may move out of alignment with respect to the cam lobe, causing an incorrect engagement between the roller and the cam lobe. Such incorrect alignment/engagement may lead to an increased friction between the roller and the cam lobe, in turn causing an increased vulnerability of roller wear (and/or cam lobe wear), and thus, potential valve train failures.
U.S. Pat. No. 3,668,945 ('945 reference) discloses a guard that prevents roller tappets of a fuel injection pump from turning about their axes, during operation. The roller tappets are provided with flattened portions that cooperate with flattened parts of a securing pin to prevent the roller tappets from rotation.
In one aspect, the disclosure is directed towards a guide assembly for a valve lifter of an engine. The valve lifter is at least partly received within a bore of a body of the engine and an end portion of the valve lifter is exposed to an outside of the body. The guide assembly includes a pin and a guide. The pin is adapted to be fixedly coupled to the end portion of the valve lifter, while the guide is adapted to be coupled to the body. The guide defines a channel, and the pin is received within the channel and cooperates with the channel to facilitate a movement of the valve lifter along an axis of the bore and restrict a rotation of the valve lifter about the axis of the bore.
In another aspect, the disclosure relates to a valve train for an engine. The engine includes a body. The valve train includes a valve lifter, a pin, and a guide. The valve lifter is adapted to be at least partly received within a bore of the body and is movable along an axis of the bore. The valve lifter includes an end portion adapted to be exposed to an outside of the body. The pin is fixedly coupled to the end portion. The guide defines a channel and is adapted to be coupled to the body. The pin is received within the channel and cooperates with the channel to facilitate a movement of the valve lifter along the axis and restrict a rotation of the valve lifter about the axis.
In yet another aspect, the disclosure is directed to an engine. The engine includes a body, a valve lifter, a pin, and a guide. The body defines a bore. The valve lifter is at least partly received within the bore and is movable along an axis of the bore. The valve lifter includes an end portion that is exposed to an outside of the body. Further, the pin is fixedly coupled to the end portion, while the guide defines a channel and is coupled to the body. The pin is received within the channel and cooperates with the channel to facilitate a movement of the valve lifter along the axis and restrict a rotation of the valve lifter about the axis.
Referring to
The engine 100 may be a reciprocating engine and may be functionally implemented as one of a diesel engine, a gasoline engine, a stratified charge compression ignition (SCCI) engine, a homogeneous charge compression ignition (HCCI) engine, etc. In an embodiment, the engine 100 may be a dual fuel engine or a gaseous engine. For example, the engine 100 may use natural gas, propane gas, methane gas or any other suitable gaseous fuel, either alone or in any combination, for combustion and subsequent operation. The engine 100 may work on a two-stroke principle or a four-stroke principle, or any other conventionally known principle. Although such configurations of the engine 100 are disclosed, aspects of the present disclosure need not be limited to any particular engine type.
The depiction of the engine 100 in
The engine 100 includes a body 102, a cylinder 104 formed within the body 102, a cylinder head 106 arranged atop the body 102 at one end of the cylinder 104, a piston 110 movably arranged within the cylinder 104, and a crankshaft 112 coupled to the piston 110 via a connecting rod 114 of the engine 100. The engine 100 also defines a combustion chamber 118 delimited by the piston 110, the cylinder head 106, and the cylinder 104, as is well known.
The engine 100 further includes a valve train 120 that may facilitate a fuel change inflow (or a compressed air charge inflow) into the combustion chamber 118 and an exhaust gas outflow from the combustion chamber 118. The valve train 120 may include one or more components, and such components may be supported and/or be accommodated by the cylinder head 106. For example, the one or more components of the valve train 120 include a pair of intake valves 124 and a pair of exhaust valves (the pair of exhaust valves are not shown). The intake valves 124 facilitate an intake of a volume of air into the combustion chamber 118, while exhaust valves facilitate a discharge of exhaust gases of combustion from the combustion chamber 118. In application, the combustion chamber 118 may receive an air-fuel mixture through the intake valves 124, and by one or more of a spark, a compression, or by other known means, the air-fuel mixture may be ignited to result in combustion within the combustion chamber 118. A combustion of the air-fuel mixture causes the piston 110 to move across a length (i.e. from a Top Dead Center (TDC) to a Bottom Dead Center (BDC)) of the cylinder 104, executing a stroke, such as a power stroke, of a combustion cycle of the engine 100. Notably, a combustion cycle involving a movement of the piston 110 to execute an intake stroke, a compression stroke, a power stroke, and an exhaust stroke, is well known, and thus, does not necessitate further discussion. A movement of the piston 110 causes the crankshaft 112 to rotate, thereby generating rotary power applicable to power a machine (or any requirement) associated with the engine 100.
Referring to
The camshaft 130 is operably engaged with the crankshaft 112, such as by a belt or by a gear, and therefore, a rotation of the crankshaft 112 results in a rotation of the camshaft 130 (or that the camshaft 130 is driven by the crankshaft 112). A rotary motion of the camshaft 130 results in an opening and a closure of the intake valves 124 (and the exhaust valves)—such an operational aspect will be understood as the disclosure proceeds. In the depicted embodiment of
A forthcoming description includes details of the first valve lifter 132 and the second valve lifter 134. Because a form and function of the second valve lifter 134 may remain similar to the first valve lifter 132, details and an environment pertaining to only the first valve lifter 132 is described. Unless specified otherwise, such details and environment described for the first valve lifter 132 will be equivalently applicable to the second valve lifter 134 (and possibly other valve lifters of the engine 100), as well. Accordingly, it may be noted that in
The valve lifter 132 is movably and at least partly received within a bore 156 of the body 102. For example, the bore 156 may define an axis 158, and the valve lifter 132 may reciprocate within the bore 156 along the axis 158. The valve lifter 132 defines a longitudinal axis 160, and includes a first end portion 164 and a second end portion 166. The first end portion 164 accommodates a roller 168 (also see exemplary roller 168 depiction provided in
The roller 168 may rotate about a roller pin 174 that is fixedly coupled to the first end portion 164 of the valve lifter 132, and which is positioned substantially perpendicularly to the longitudinal axis 160 of the valve lifter 132. The term “substantially perpendicularly” means that an angle between an axis of the roller pin 174 and the longitudinal axis 160 of the valve lifter 132 is close to being a right angle, barring angular differences arising due to manufacturing tolerances. The roller 168 is in slidable engagement with the cam lobe 150 and rides on the cam lobe 150, ensuring that a characteristic profile of the cam lobe 150 is followed by the roller 168 as the cam lobe 150 rotates (see direction, A) with the camshaft 130, during operation. Due to such slidable engagement between the roller 168 with the cam lobe 150, the cam lobe 150 facilitates a reciprocal movement of the valve lifter 132 within the bore 156, along the axis 158 of the bore 156.
At the second end portion 166 of the valve lifter 132, the valve lifter 132 is coupled to the pushrod 138 (see
On occasions, during busy valve closure and opening events, such as via the mechanism discussed above, the valve lifter 132 may be subject to operational forces, and one or more components of such forces may undesirably cause the valve lifter 132 to turn and/or rotate about the longitudinal axis 160. One or more aspects of the present disclosure contemplates the use of the guide assembly 136 that is adapted to restrict such a rotation.
The guide assembly 136 includes a guide 182 and a pin 184. The pin 184 is in engagement with the valve lifter 132, as may be understood from the below description. As shown in
The pin 184 is adapted to be fixedly coupled to the second end portion 166 of the valve lifter 132. By way of a fixed coupling of the pin 184 to the valve lifter 132, the pin 184 may move with a longitudinal movement of the valve lifter 132. For example, a reciprocal movement of the valve lifter 132 along the axis 158 may result in a synchronously attained movement of the pin 184, as well.
In one implementation, the pin 184 is adapted to be coupled to the second end portion 166 of the valve lifter 132 such that the pin 184 protrudes radially outwardly from the flanged portion 170 (also see
The guide 182 is adapted to be coupled to the body 102 of the engine 100. The guide 182 includes an upper section 190 and a lower section 192. The upper section 190 may include a U-shaped profile (see
According to one embodiment, the guide members 200, 202 may include a rectangular shaped profile, as shown. Accordingly, the channel 204, defined between the guide members 200, 202, may include a rectangular shaped profile, as well. The channel 204 may be open from three sides (of such a rectangular shaped profile), as shown, with each open side facilitating access into the channel 204 thereof. A fourth side of the channel 204 however may be closed by the arcuate section 206. Understandably, therefore, the guide 182 may define an upper guide end 208, oppositely to the arcuate section 206, where the channel 204 may be open, and through which it is possible to receive the pin 184 into the channel 204, during assembly. Given the rectangular profile of the channel 204, the channel 204 also defines a length and a breadth. The length is defined along an extension of the arcuate section 206, and understandably, the breadth of the channel 204 is defined at right angles to the length (see
A dimension of the channel 204 may compliment and match with a dimension of the pin 184 so that the channel 204 may receive the pin 184, during assembly. For example, the channel width, W, may be similar to a thickness (or a diameter) of the pin 184. The term ‘similar’ may be understood as a reference to a similarity that exists between a dimension of thickness of the pin 184 and a dimension of the channel width, W, and not equality—understandably, for the channel 204 to receive and compliment the pin 184, the channel width, W, may be slightly larger than the thickness of the pin 184. Therefore, in assembly, the pin 184 may clear the channel width, W, and be accommodated within the channel 204 of the guide 182, but with a minimal clearance existing between pin 184 and the guide members 200, 202 with such minimal clearance being maintained such that a play between the channel 204 and the pin 184 is minimized. Notably, such minimal clearance may vary and may not remain same for all engine configurations, and may thus take any industrially accepted value. As the pin 184 is received within the channel 204, the pin 184 is also able to cooperate with the channel 204 during a movement of the valve lifter 132 along the axis 158 of the bore 156. A cooperation between the channel 204 and the pin 184 facilitates a movement of the valve lifter 132 along the axis 158 of the bore 156, but also restricts a rotation of the valve lifter 132 about the axis 158 of the bore 156.
The lower section 192 of the guide 182 extends from the upper section 190 to a lower end 210 of the guide 182. In an embodiment, the guide 182 may be coupled to the body 102 by at least a partial insertion of the lower section 192 into the body 102. The lower section 192 may be integrally formed with the upper section 190. Further, as shown, the lower section 192 may include one or more stems, for example a first stem 212 and a second stem 214, integrally and contiguously extending from the upper section 190. Although two stems are contemplated, additional or lesser stems may also be contemplated.
It may be noted that the first stem 212 and the second stem 214 facilitate a coupling of the guide 182 to the body 102 of the engine 100. To this end, the body 102 includes one or more slots—namely a first slot 220 and a second slot 222 (see
Further, each of the first stem 212 and the second stem 214 may include a passageway, termed respectively as a first passageway 232 and a second passageway 234. The passageways 232, 234 are provided so as to facilitate a release of a volume of air that may be trapped within the slots 220, 222 during an assembly of the stems 212, 214 into the slots 220, 222.
By having the two stems 212, 214, it is possible for the guide 182 to be restricted against a rotating torque acting against the guide 182, during operation. Although such a two-stem configuration is proposed in the above discussion, it is possible that the guide 182 may include a single stem configuration as well. For example, it is possible for a single stem to include one or more planar surface, that may cooperate against one or more planar surfaces of a corresponding slot, similar to slots 220, 222 formed within the body 102 of the engine 100, to prevent any torque acting against the guide 182 from turning from a preset, desired arrangement of the guide 182.
During assembly, an operator may first mount the guide 182 to the body 102 of the engine 100. This is performed by inserting and press-fitting the stems 212, 214 into the slots 220, 222. In some implementations, the stems 212, 214 are inserted till the upper section 190 abuts against the body 102 of the engine 100, leaving the upper section 190, and thus the channel 204, exposed to the outside of the body 102. Thereafter, the operator may bring forth the pin 184 and may insert the pin 184 into the aperture 188 and couple the pin 184 with the flanged portion 170 such that a portion of the pin 184 extends radially outwardly of the flanged portion 170. In that manner, the pin 184 is fixedly coupled to the valve lifter 132. Thus, at this point in assembly, the pin 184 extends radially outwardly relative to the longitudinal axis 160 of the valve lifter 132, as well. The operator may then insert the valve lifter 132 into the bore 156 such that the longitudinal axis 160 of the valve lifter 132 falls in line with the axis 158 of the bore 156, and also ensuring that the pin 184 (or at least a portion of the pin 184), slides into and is received within the channel 204 of the guide 182 from the upper guide end 208 (or from the fourth side of the channel 204). The insertion process is performed till the roller 168 of the valve lifter 132 abuts the cam lobe 150, and is slidably engaged with the cam lobe 150. In this position, at least a portion of the flanged portion 170 (i.e. the second end portion 166) remains exposed to the outside of the body 102. Once such an arrangement is attained, remaining components of the valve train 120, such as the valve bridge 142, the rocker arm 140, etc., are brought forth and are then assembled to the valve lifter 132. Since both the second end portion 166 and the upper section 190 of the guide 182 are exposed to the outside of the body 102, an assembly and removal of the guide assembly 136 is more easily attained (for example from a top of the engine 100) than conventional assembly/re-assembly practices, thus mitigating operator effort and time.
During operation, the valve lifter 132 is pushed by the cam lobe 150, by a rotation of the cam lobe 150, in a recurring manner. This push facilitates a translation of the valve lifter 132 along the axis 158 of the bore 156, converting the rotating action of the cam lobe 150 into a reciprocation of the valve lifter 132. Consequentially, the pin 184, fixedly coupled to the second end portion 166 of the valve lifter 132, reciprocates with the valve lifter 132 as well, moving and cooperating with the channel 204 along a direction parallel to the longitudinal axis 160 of the valve lifter 132. As the channel 204 is free to accommodate reciprocal movements of the pin 184 along a direction parallel to the longitudinal axis 160 of the valve lifter 132, the pin 184 moves freely along a direction parallel to the longitudinal axis 160 of the valve lifter 132. However, given the minimal clearance between the guide members 200, 202 and the pin 184, the pin 184 is restricted from rotating about the axis 158 of the bore 156. Owing to the profile of the channel 204, effectively, the channel 204 facilitates a movement of the valve lifter 132 along the axis 158 of the bore 156 and restricts a rotation of the valve lifter 132 about the axis 158 of the bore 156.
Although a number of components of the valve train 120 is disclosed, it is possible that one or more aspects of the present disclosure are implemented with one or more of these components removed or omitted from the engine 100. In some cases, therefore, a description of an immediate environment surrounding the valve lifter 132, the guide 182, and the pin 184, may be seen as being purely exemplary in nature, and it may be understood that the present disclosure discusses such an environment only to contemplate and explain one possible application of the valve train 120.
It will be apparent to those skilled in the art that various modifications and variations can be made to the system of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalent.
