CN113882945A

CN113882945A - Multi-cylinder engine

Info

Publication number: CN113882945A
Application number: CN202010974073.6A
Authority: CN
Inventors: 格斯·亚历山大; 理查德·J·吉尔帕特里克; 布赖恩·W·哈伯德; 乔治·帕纳约蒂斯·克洛尼斯; 迈克尔·赫根·伊努耶; 丹尼尔·L·赖利
Original assignee: FNA Group Inc
Current assignee: FNA Group Inc
Priority date: 2020-07-02
Filing date: 2020-09-16
Publication date: 2022-01-04
Also published as: CN113882943A; CN113882944A; CN113882942A

Abstract

The internal combustion engine may include: a first piston reciprocally disposed in the first cylinder; and a second piston reciprocally disposed in the second cylinder. The crankshaft may be coupled with the first and second pistons for rotational motion associated with reciprocating motion of at least one of the first and second pistons. The combustion chamber may be fluidly coupled with the first cylinder and the second cylinder. The ignition source may be at least partially disposed within the combustion chamber. An intake valve may provide selective fluid communication between the intake system and the combustion chamber, and an exhaust valve may provide selective fluid communication between the exhaust system and the combustion chamber.

Description

Multi-cylinder engine

Cross Reference to Related Applications

The present application claims benefit of U.S. provisional application serial No. 63/047,470 entitled Multiple Cylinder Engine (Multiple Cylinder Engine) filed on day 7, month 2, 2020, the entire disclosure of which is incorporated herein by reference.

Technical Field

The present disclosure relates generally to internal combustion engines, and more particularly to multi-cylinder internal combustion engines.

Background

Internal combustion engines are widely used for various purposes. In many instances, internal combustion engines are used as the power components of power plants, particularly where it is inconvenient or impractical to use an electric motor, such as when residential or commercial power is unavailable or when power lines or extension cords may be burdensome or dangerous. For example, outdoor power equipment such as lawn mowers, power washers, snow blowers, and the like typically utilize an internal combustion engine as a power source. Typically, in such applications, the internal combustion engine may comprise a single cylinder, relatively small displacement engine. While such engines are generally cost effective and simple, there are many opportunities to improve the function, performance, and/or operation of such internal combustion engines.

Disclosure of Invention

According to an embodiment, the internal combustion engine may comprise: a first piston reciprocally disposed in the first cylinder; and a second piston reciprocally disposed in the second cylinder. The crankshaft may be coupled with the first and second pistons for rotational motion associated with reciprocating motion of at least one of the first and second pistons. The combustion chamber may be fluidly coupled with the first cylinder and the second cylinder. The ignition source may be at least partially disposed within the combustion chamber. The intake valve may provide selective fluid communication between the intake system and the combustion chamber. An exhaust valve may provide selective fluid communication between the exhaust system and the combustion chamber.

One or more of the following features may be included. The crankshaft may be configured to be disposed in a generally vertical orientation during operation. The first cylinder and the second cylinder may be arranged in a parallel inline configuration. The first cylinder and the second cylinder may be arranged in an offset configuration. The first cylinder and the second cylinder may have substantially the same diameter. The first cylinder and the second cylinder may have different diameters. The crankshaft may be coupled to the first piston by a first crank journal and may be coupled to the second piston by a second crank journal. The crankshaft may be coupled with the first piston and the second piston by a first crank journal.

The combustion chamber may include a cavity covering at least a portion of the first cylinder and at least a portion of the second cylinder. The combustion chamber may include a first cavity portion at least partially covering at least a portion of the first cylinder and a second cavity portion at least partially covering at least a portion of the second cylinder. The first cavity portion may be at least partially separated from the second cavity portion. The ignition source may include a spark plug. The ignition source may include a first spark plug associated with a first cylinder and a second spark plug associated with a second cylinder.

The intake and exhaust valves may be arranged in an overhead valve configuration. The intake and exhaust valves may be arranged in a flat head configuration.

According to another embodiment, the internal combustion engine may include: a first piston reciprocally disposed in the first cylinder; and a second piston reciprocally disposed in the second cylinder. The second piston may have a diameter smaller than a diameter of the first piston. The second piston may be disposed vertically above the first piston during operation. The crankshaft may be coupled with the first and second pistons for rotational motion associated with reciprocating motion of at least one of the first and second pistons. The crankshaft may be configured to be disposed in a generally vertical orientation during operation. The combustion chamber may be fluidly coupled with the first cylinder and the second cylinder. The ignition source may be at least partially disposed within the combustion chamber. The intake valve may provide selective fluid communication between the intake system and the combustion chamber. An exhaust valve may provide selective fluid communication between the exhaust system and the combustion chamber.

One or more of the following features may be included. The first cylinder and the second cylinder may be formed in an engine block. The engine block may include a plurality of fins configured to provide air cooling to the internal combustion engine. The crankshaft may be coupled with the first piston and the second piston by a first crank journal. The crankshaft may be coupled to the first piston by a first crank journal and may be coupled to the second piston by a second crank journal.

According to yet another embodiment, the internal combustion engine may include: a first piston reciprocally disposed in a first cylinder, the first cylinder having a first diameter; and a second piston reciprocally disposed in a second cylinder having a second diameter substantially the same as the first diameter. The crankshaft may be coupled with the first and second pistons for rotational motion associated with reciprocating motion of at least one of the first and second pistons. The crankshaft may be configured to be disposed in a generally vertical orientation during operation. The combustion chamber may be fluidly coupled with the first cylinder and the second cylinder. The ignition source may be at least partially disposed within the combustion chamber. The intake valve may provide selective fluid communication between the intake system and the combustion chamber. An exhaust valve may provide selective fluid communication between the exhaust system and the combustion chamber.

One or more of the following features may be included. The first cylinder and the second cylinder may be formed in an engine block. The engine block may include a plurality of fins configured to provide air cooling to the internal combustion engine.

Drawings

1-4 show illustrative example embodiments of a multi-cylinder internal combustion engine including a plurality of firing cylinders, according to an example embodiment;

5-8 show another illustrative example embodiment of a multi-cylinder internal combustion engine including a plurality of firing cylinders, according to an example embodiment;

9-12 show another illustrative example embodiment of a multi-cylinder internal combustion engine including a plurality of firing cylinders, according to an example embodiment;

13-17 illustrate various piston connecting rod configurations for a multi-cylinder internal combustion engine, according to various exemplary embodiments;

FIG. 18 shows an illustrative example combustion chamber configuration that may be used in conjunction with a multi-cylinder internal combustion engine including a plurality of firing cylinders, according to an example embodiment;

19-23 schematically illustrate various cylinder and valve arrangements that may be used in conjunction with an internal combustion engine having multiple firing cylinders, according to various exemplary embodiments;

FIG. 24 schematically illustrates a portion of a flathead internal combustion engine including a plurality of ignition cylinders, according to an exemplary embodiment;

25-33 illustrate various piston and valve arrangements that may be used in conjunction with an internal combustion engine including a plurality of ignition cylinders, in accordance with various embodiments;

34-37 show an illustrative example embodiment of a multi-cylinder internal combustion engine according to an example embodiment;

FIG. 38 shows another illustrative example embodiment of a multi-cylinder internal combustion engine according to an example embodiment;

39-40 show illustrative example embodiments of check valve arrangements that may be used in conjunction with a multi-cylinder internal combustion engine, according to various example embodiments;

41-43 show various illustrative example embodiments of an accumulator according to various example embodiments;

44-47 show another illustrative example embodiment of a multi-cylinder internal combustion engine according to an example embodiment;

FIG. 48 schematically shows an illustrative example embodiment of a hydraulic motor fluid path that may be used in conjunction with a multi-cylinder internal combustion engine, according to an example embodiment;

49-53 show another illustrative example embodiment of a multi-cylinder internal combustion engine according to an example embodiment;

FIG. 54 shows another illustrative example embodiment of a multi-cylinder internal combustion engine according to an example embodiment;

FIG. 55 shows another illustrative example embodiment of a multi-cylinder internal combustion engine according to an example embodiment;

56-59 show another illustrative example embodiment of a multi-cylinder internal combustion engine according to an example embodiment;

FIG. 60 shows another illustrative example embodiment of a multi-cylinder internal combustion engine according to an example embodiment;

FIG. 61 shows another illustrative example embodiment of a multi-cylinder internal combustion engine according to an example embodiment; and is

FIG. 62 is a block diagram of an intake system and an exhaust system that may be used in conjunction with a multi-cylinder internal combustion engine, according to an exemplary embodiment.

Detailed Description

Generally, the present disclosure relates to internal combustion engines having multiple cylinders. For clarity of description and illustration, the present disclosure will generally relate to an internal combustion engine including two cylinders. However, it will be appreciated that internal combustion engines consistent with the present disclosure may include a greater number of cylinders. As such, the present disclosure should not be limited to internal combustion engines having only two cylinders. Consistent with the present disclosure, an internal combustion engine may include a four-stroke engine, such as a gasoline engine or a propane engine. In other embodiments, the engine may comprise a diesel engine or a two-stroke engine. In some embodiments, the engine may comprise an air cooled engine, for example, wherein at least a portion of the cooling of the engine is achieved by radiation cooling and/or convection cooling of at least a portion of the engine. For example, at least a portion of an engine, such as an engine block (which may contain and/or define one or more cylinders) and/or a cylinder head (which may contain and/or define at least a portion of a combustion chamber, for example) may include fins or other features that may facilitate radiant and/or convective cooling of the engine (e.g., due to movement of air over such features). In some embodiments, at least a portion of the cooling may be achieved through the use of a liquid heat transfer medium, such as lubricating oil for an engine, a coolant based on water, glycol, or the like, and the like. Consistent with some such embodiments, the liquid heat transfer medium may splash onto one or more pistons of the engine, may pass (e.g., through a liquid passage) through at least a portion of the engine block and/or cylinder head, and/or the like. In some such embodiments, the liquid may further pass through a heat transfer structure, such as a liquid-to-air heat exchanger (e.g., a radiator) and/or may pass through a reservoir (e.g., a crankcase) that may have fins and/or other heat dissipating structural containers.

According to some embodiments, an internal combustion engine consistent with the present disclosure may include a plurality of cylinders (each having a corresponding reciprocating piston) that may participate, at least in part, in a four-cycle combustion process. That is, two or more cylinders may participate in one or more of the intake of a fuel-air mixture, the compression of a fuel-air mixture, the combustion of a fuel-air mixture, the power generation of a fuel-air mixture, and the exhaust of the products of combustion of a fuel-air mixture. For example, at least two cylinders may be at least partially filled with a fuel-air mixture, and corresponding pistons in the at least two cylinders may be caused to reciprocate within the corresponding cylinders at least partially by combustion of the fuel-air mixture. Cylinders that may be at least partially involved in the combustion process may also be referred to herein as firing cylinders.

According to some embodiments, an internal combustion engine consistent with the present disclosure may include one or more ignition cylinders, and may include one or more additional cylinders (e.g., which may include respective reciprocating pistons) that may assist at least a portion of the operation of the internal combustion engine. For example, in some embodiments, an internal combustion engine may include at least one firing cylinder and at least one cylinder that may perform a fluid pumping function. In some such embodiments, at least one cylinder performing a fluid pumping function may pressurize fluid (e.g., gas or liquid) within the accumulator. The pressurized fluid may be selectively released from the accumulator to assist at least a portion of the operation of the engine, such as for starting the internal combustion engine, and/or to assist in starting the internal combustion engine. In some embodiments, at least one cylinder performing the fluid pumping function may deliver air and/or a fuel-air mixture from at least one firing cylinder. Consistent with such an embodiment, at least one cylinder performing the fluid pumping function may pre-charge at least one firing cylinder, which may increase a fuel-air volume within the at least one firing cylinder (e.g., as compared to a fuel-air volume that may be achieved within the at least one firing cylinder without the at least one cylinder assist performing the pumping function).

According to some embodiments, an internal combustion engine consistent with the present disclosure may include one or more than one ignition cylinder, and may include at least one cylinder (including a respective reciprocating piston), wherein the respective reciprocating piston may impart vibrational characteristics to the internal combustion engine. For example, the vibration characteristics may at least partially cancel vibration caused by the ignition cylinder (i.e., reciprocation of the ignition piston), and/or the vibration characteristics of the internal combustion engine may be adjusted, such as by changing vibration caused by the ignition piston and/or other components of the internal combustion engine (e.g., valve camshaft, valves, crankshaft, etc.).

An internal combustion engine consistent with a first illustrative example embodiment according to the present disclosure is shown. As shown, the internal combustion engine is an air-cooled four-stroke engine, as generally discussed above. Further, as generally shown, an internal combustion engine may generally include: a first piston reciprocally disposed in the first cylinder; and a second piston reciprocally disposed in the second cylinder. The crankshaft may be coupled with the first and second pistons for rotational motion associated with reciprocating motion of at least one of the first and second pistons. That is, for example, rotation of the crankshaft may cause reciprocation of the first and second pistons. Similarly, reciprocation of the first piston and/or the second piston may cause rotation of the crankshaft. The internal combustion engine may also include a combustion chamber fluidly coupleable with the first cylinder and the second cylinder. That is, the combustion chamber, along with the first and second cylinders, may define a fluid volume (e.g., the fluid volume may vary according to the reciprocal motion and/or position of the first and second pistons within the respective first and second cylinders). In some such embodiments, the combustion chamber may be disposed at a distal end of the first and second cylinders (e.g., relative to the crankshaft), and may at least partially surround the distal ends of the first and second cylinders.

The internal combustion engine may also include an ignition source that may selectively ignite one or both of the first cylinder, the second cylinder, and the fuel-air mixture in the combustion chamber. In some embodiments, the ignition source may be at least partially disposed within the combustion chamber. The internal combustion engine may also include one or more intake valves that may provide selective fluid communication between the intake system and the combustion chamber. For example, one or more intake valves may be selectively opened (e.g., at least during an intake cycle of the internal combustion engine) to allow a fuel-air mixture to be drawn into one or more of the first cylinder, the second cylinder, and the combustion chamber through an intake runner or manifold, which may be coupled with a carburetor or a fuel injection system (e.g., to facilitate mixing of fuel and air prior to or during entry of the fuel-air mixture through the intake valves), for example. The intake valve may also be selectively closed to prevent flow back into the intake system from one or more of the first cylinder, the second cylinder, and the combustion chamber (e.g., during one or more of a compression cycle, a power cycle, and an exhaust cycle of the internal combustion engine). The internal combustion engine may also include an exhaust valve that may provide selective fluid communication between the exhaust system and the combustion chamber. That is, the exhaust valves may be selectively opened to allow the combusted fuel-air mixture to be exhausted from one or more of the first cylinder, the second cylinder, and the combustion chamber (e.g., at least during an exhaust cycle of the internal combustion engine). The exhaust system may include, for example, an exhaust runner and/or an exhaust manifold, which may be coupled with a muffler, for example. In a similar manner as the intake valves, the exhaust valves may be selectively closed, for example, to prevent flow from one or more of the first cylinder, the second cylinder, and the combustion chamber into the exhaust system (e.g., during one or more of an intake cycle, a compression cycle, and a power cycle of the internal combustion engine).

Continuing with the foregoing, and with further reference to at least fig. 1-4, an illustrative example embodiment of an internal combustion engine 10a is shown. As shown, the internal combustion engine 10a may comprise an air-cooled four-stroke engine, as generally discussed above. Further, as generally shown, an internal combustion engine may generally include: a first piston 12a reciprocally disposed in the first cylinder 14 a; and a second piston 16a reciprocally disposed within a second cylinder 18 a. The internal combustion engine 10a may also include a crankshaft 20a that may be coupled with the first and second pistons for rotational motion associated with the reciprocating motion of at least one of the first and second pistons. As generally discussed above, the first and

second pistons

12a and 16a may be moved in a reciprocating manner within the respective first and

second cylinders

14a and 18a to intake a fuel-air mixture into the internal combustion engine, compress the fuel-air mixture, generate power as the fuel-air mixture combusts, and expel the combusted fuel-air mixture. Generally, the reciprocating motion of the first and

second pistons

12a and 16a may be caused by the rotational inertia of the crankshaft 20 a. The reciprocating motion of the first and

second pistons

12a, 16a may be based, at least in part, on combustion of a fuel-air mixture, which in turn may impart rotational motion to (and/or increase rotational inertia of) the crankshaft 20 a.

As generally shown, the internal combustion engine 10a may additionally include a crankcase 22a or engine housing in which the crankshaft 20a may be at least partially disposed and/or supported. Further, the internal combustion engine may include an engine block 24 a. As shown, the first cylinder 14a and the second cylinder 18a may be at least partially and/or entirely disposed and/or formed within the engine block 24 a. As also shown, for example, in fig. 3 and 4, the internal combustion engine 10a may further include, for example, a cylinder head 26a, which may at least partially cover a distal end (relative to the crankshaft) of the engine block 24a and the first and

second cylinders

14a, 18 a.

Consistent with some embodiments, the crankshaft 20a may be configured to be disposed in a generally vertical orientation during operation. For example, as generally shown in fig. 1-3, during intended operation of the internal combustion engine 10, the crankshaft 20a may be disposed in a generally vertical orientation and the motion of the first and

second cylinders

14a, 18a (and the reciprocating motion of the first and

second pistons

12a, 16 a) may be in a generally horizontal orientation. However, it should be understood that the orientation of the crankshaft 20a may vary during use. For example, the internal combustion engine 10 may be coupled to a housing, chassis, or piece of power equipment (e.g., without limitation, a lawn mower, a high pressure washer, a snow blower, etc.), which may be disposed on or through an angled surface. Thus, during use of the internal combustion engine 10, the crankshaft 20a may be positioned in an orientation that is generally different than vertical.

Consistent with certain embodiments, such as those shown in connection with the internal combustion engine 10a shown in fig. 1-4, the first cylinder 14a and the second cylinder 18a may be arranged in a parallel inline configuration. That is, and with particular reference to fig. 3 and 4, the crankshaft 20a may lie in a plane passing through the centerlines of the first and

second cylinders

14a and 18 a. In this regard, the first cylinder 14a and the second cylinder 18a may be parallel to each other and may be in line with each other and the crankshaft 20 a.

Consistent with some embodiments, the first cylinder and the second cylinder may be arranged in an offset configuration. For example, and with reference to the illustrative example embodiment shown in fig. 5-8, an internal combustion engine 10b is shown that includes a first piston 12b reciprocally disposed within a first cylinder 14b and a second piston 16b reciprocally disposed within a second cylinder 18 b. As shown, the first cylinder 14b and the second cylinder 18b may be offset from one another relative to a crankshaft 20b to which the first piston 12b and the second piston 16b are coupled. That is, the crankshaft 20b does not lie in a plane passing through the centerlines of the first and

second cylinders

14b and 18 b. Consistent with this configuration, the first cylinder 14b and the second cylinder 18b may be arranged in an at least partially V-shaped configuration. As shown, the first cylinder 14b and the second cylinder 18b may be arranged in a shallow V-shaped configuration, for example, wherein the first cylinder 14b and the second cylinder 18b may at least partially overlap when the first cylinder 14b and the second cylinder 18b are partially offset. Consistent with this configuration, the first cylinder 14b and the second cylinder 18b may be formed within a single cylinder block 24b and may be at least partially surrounded by a single cylinder head 26 b. However, it should be understood that while the embodiments shown in fig. 5-8 include a shallow V-shaped configuration, other configurations (e.g., may include a deeper V-shaped configuration in which the cylinders may only partially overlap and/or may not overlap) are also contemplated within the present disclosure.

It will be appreciated that in some embodiments, where the cylinder is at least partially offset from either side of the crankshaft centerline during reciprocation of the pistons (which may be coupled with the crankshaft), one of the pistons may "guide" the other piston. That is, for example, the reciprocation of one piston may be slightly advanced relative to the reciprocation of the other piston. In this regard, one piston may arrive at top dead center slightly ahead of the other piston (e.g., in time and/or based on the rotational cycle of the crankshaft), and may arrive at bottom dead center at least slightly ahead of the other piston. In some embodiments, this pilot piston property may be utilized, for example, to slightly increase the compression pressure of the fuel-air mixture at ignition. For example, it is common for an internal combustion engine to ignite a cylinder (i.e., the fuel-air mixture within or associated with a particular cylinder) to some extent before the piston reaches top dead center. In arrangements including offset cylinders, the pilot piston may be allowed to advance further toward (or beyond) top dead center prior to ignition than would normally occur. This may result in a relatively high fuel-air mixture pressure at ignition (e.g., the trailing piston is closer to the normal position at ignition). It should be understood that other configurations may also be utilized.

In some example embodiments consistent with the present disclosure, the first cylinder and the second cylinder may have substantially the same diameter. For example, as shown in the illustrative example

internal combustion engines

10a, 10b shown in fig. 1-8, the first and

second cylinders

14a, 14b, 18a, 18b may have substantially the same diameter. Consistent with some such embodiments, the engine displacement may generally be divided equally between two cylinders (although the geometry of the combustion chamber may affect the division of the total engine displacement between cylinders). Furthermore, it should be understood that the pistons may also have substantially the same diameter, similar to the cylinders. Additionally, it should be understood that the description of substantially the same diameter is not intended to require exactly the same diameter, but should also be construed to cover minor differences in diameter.

Consistent with some embodiments, the first cylinder and the second cylinder may have different diameters, except for embodiments including cylinders having substantially the same diameter. For example, and referring also to fig. 9-12, an illustrative example embodiment of an internal combustion engine 10c is shown including a first piston 12c reciprocally disposed in a first cylinder 14c and a second piston 16c reciprocally disposed in a second cylinder 18 c. As shown in the depicted embodiment, the first cylinder 14c may have a larger diameter than the second cylinder 18 c. Consistent with various embodiments, the difference in diameter between the first cylinder and the second cylinder may be relatively small, and/or may be relatively significant. For example, the diameter of the second cylinder may be between about 90% to about 10% of the diameter of the first cylinder, although the difference between the diameters of the cylinders may be greater or smaller. Consistent with the embodiment shown in fig. 9-12, the second cylinder 18c having a relatively smaller diameter may be disposed in a top position (e.g., generally vertically above the first cylinder 14c having a larger diameter). In some cases, such a configuration may facilitate lubrication of the crankshaft and pistons (e.g., in an engine configuration with a substantially vertical crankshaft). However, in other embodiments, a relatively smaller cylinder may be disposed in a bottom position (e.g., generally below a relatively larger diameter cylinder). Additionally, although the first and

second cylinders

14c, 18c are shown as having a generally parallel inline configuration, this is for illustrative purposes only and is not limiting. In particular, it should be appreciated that an internal combustion engine having two or more cylinders may include cylinders arranged in an offset configuration, as generally shown and described with respect to the embodiment shown in fig. 5-8.

As generally described above, a crankshaft may be coupled with the first and second pistons for rotation of the crankshaft associated with the reciprocating motion of the first and/or second pistons. In particular, in some embodiments, rotation of the crankshaft may result in reciprocating motion of the first piston and/or the second piston. Correspondingly, the reciprocating motion of the first piston and/or the second piston may result in rotation of the crankshaft. As discussed above, during operation of an internal combustion engine consistent with the present disclosure, both motion modes may be involved during different operating cycles of the internal combustion engine (e.g., rotation of the crankshaft may drive reciprocation of one or more pistons, and the resulting reciprocation of one or more pistons may drive rotation of the crankshaft). Consistent with the present disclosure, one or both of the pistons may be associated with a crankshaft to cause corresponding movement thereof in various ways.

Consistent with example embodiments, the crankshaft may be coupled with the first piston by a first crank journal and may be coupled with the second piston by a second crank journal. It should be understood that a crank journal, which may generally refer to a portion of a crankshaft that is offset from a crankshaft centerline, is configured to couple with a connecting rod to rotate the crankshaft in association with the reciprocating motion of a piston connected to the connecting rod. The crank journal may also be referred to as a crankpin. With respect to the exemplary internal combustion engine 10b shown and the exemplary internal combustion engine 10c shown, an exemplary arrangement is shown, for example, in fig. 7 and 11, which includes a crankshaft coupled with a first piston via a first crank journal and a second piston via a second crank journal. As shown, for example, in FIG. 7, the crankshaft 22b may generally include a first crank journal 28b and a second crank journal 30 b. The first piston 12b may be coupled to the crankshaft 22b by a first crank journal 28b, and the second piston 16b may be coupled to the crankshaft 22b by a second crank journal 30 b. Similarly, as shown in FIG. 11, the crankshaft 22c may include a first crank journal 28c and a second crank journal 30c, relative to the exemplary internal combustion engine 10c shown. The first piston 12c may be coupled to the crankshaft by a first crank journal 28c, and the second piston 16c may be coupled to the crankshaft 22c by a second crank journal. Consistent with some such embodiments, a crankshaft comprising two crank journals may further comprise a counterweight between at least a first crank journal and a second crank journal. For example, as shown in fig. 7, the crankshaft 22b may include three

counterweights

32b, 34b, 36b, wherein the counterweight 34b may be disposed between the first crank journal 26b and the second crank journal 28 b.

In an example embodiment consistent with the present disclosure, a crankshaft may be coupled with a first piston and a second piston by a first crank journal. For example, and with reference to the illustrated example, the internal combustion engine 10a shown in fig. 3 includes a crankshaft 22a that includes a single crank journal (i.e., a first crank journal 28 a). As shown, both the first piston 12a and the second piston 16a are coupled to the crankshaft 22a by a first crank journal 28 a. Further, as shown, the crankshaft 22a includes a counterweight 32a on the outside of the connection with the first piston 12a, a counterweight 36a on the outside of the connection with the second piston 16a, with no counterweight between the connections with the two pistons. It should be understood that the crankshaft, as shown, includes only a single crank journal or crank pin. However, in some embodiments, it may not be necessary to finish the entire surface of a single crank journal to a bearing surface finish (e.g., a high degree of polishing and/or very high round tolerances). For example, the area associated with the connection of the first piston and the area associated with the connection of the second piston may be finished to a bearing surface finish, while the area of the crank journal between these two connection points may be finished less well.

As generally discussed above, the first and second pistons may be arranged in various configurations (e.g., parallel inline and offset configurations), and the first and second pistons may be coupled with the crankshaft in various configurations (e.g., each piston is coupled to a separate respective crank journal, and both pistons are coupled to the same single crank journal). Accordingly, it should be understood that various link configurations may be utilized. Connecting rods are known to provide a physical connection between a piston and a crank journal of a crankshaft. Referring additionally to fig. 13-17, various exemplary crankshaft and connecting rod configurations are shown.

Referring to fig. 13 and 14, two illustrative example crankshaft and connecting rod configurations including a first crank journal and a second crank journal are shown. As shown in FIG. 13, according to an exemplary embodiment, the crankshaft 22d may include a first crank journal 28d and a second crank journal 30 d. The crankshaft may be coupled to the two pistons using a substantially straight connecting rod 38 a. Referring still to FIG. 14, in another illustrative example embodiment, a crankshaft 22e is shown including a first crank journal and a second crank journal. As shown, the crankshaft may be coupled to two respective pistons by connecting rods 38b, which may have the same configuration, one of which is flipped 180 degrees relative to the other. As shown, the connecting rod 38b may include an in-plane bend or tap adjacent the piston. In some embodiments, such a configuration may facilitate an offset cylinder configuration.

Referring to fig. 15-17, various illustrative example crankshaft and connecting rod configurations are shown by which two pistons may be coupled to a crankshaft by a single crank journal. Although the illustrated embodiments described above show pistons having substantially similar diameters, in some embodiments, the pistons may have different diameters, as discussed above. It should be understood that the illustrated connecting rod arrangement may be adapted to accommodate various piston diameters and relative differences in diameters. As previously discussed with respect to fig. 3, in one embodiment, the crankshaft 22a may include a generally elongated crank journal 28 a. Consistent with the example configuration shown, the first and

second pistons

12a, 16a may be coupled to the crank journal 28a by a straight connecting rod of generally conventional configuration. Consistent with such an embodiment, the crank journal may be long enough to span a sufficient extent of the first and

second cylinders

14a, 18a to provide a connecting rod bearing surface generally in the region of the central axes of the first and

second pistons

12a, 16 a.

With additional reference to fig. 15-17, various additional connecting rod configurations are shown that can suitably couple two pistons to a single crank journal. For example, in the example embodiment shown in FIG. 15, a configuration is shown in which one of the pistons may be coupled with the crankshaft using a substantially straight connecting rod 38 a. Additionally, the other piston may be coupled to the crankshaft by an offset connecting rod 38c (via the same crank journal). As shown, the offset link 38c may be laterally offset from the link 38 a. Thus, the offset connecting rod 38c may increase the spacing between the two pistons, for example, to provide sufficient clearance between the two pistons to allow the two pistons to reciprocate in their respective associated cylinders. Referring to fig. 16, in another illustrative example embodiment, two pistons may be coupled to a crankshaft by a single wishbone connecting rod 38d by a single crank journal. As shown, wishbone connecting rod 38d may include a single bearing for coupling with a crank journal, and may be forked to allow the connecting rod to connect to two separate pistons. As shown, the arms of the wishbone connecting rod may be offset from each other sufficiently in the transverse direction to accommodate two pistons (e.g., two piston-to-connecting rod fittings, and/or the reciprocating motion of the pistons in respective cylinders). Although the illustrated example wishbone link 38d is shown as being generally symmetrical, e.g., each prong of the link is laterally offset by a generally similar amount, it should be understood that in other embodiments, both prongs may be asymmetrical, e.g., one prong is laterally offset to a greater extent than the other. In another embodiment, one prong of the connecting rod may be substantially straight, and only one prong of the connecting rod may be laterally offset to provide sufficient clearance for coupling with both pistons.

Still referring to FIG. 17, according to yet another illustrative example embodiment, two pistons may be connected to a single crank journal of a crankshaft by two separate skewed connecting rods 38 e. Consistent with the illustrated embodiment, the two skew links 38e may have a generally similar configuration, with one link flipped 180 degrees. Consistent with the example embodiment shown, the deflection links 38e may each deflect at least partially inward toward one another, e.g., to provide a biased configuration of the pistons relative to one another.

While there are several illustrative example embodiments of crankshaft and connecting rod arrangements for coupling a piston with a crankshaft, it should be understood that a wide variety of additional and/or alternative configurations may be equally utilized. In this regard, the present disclosure should not be limited to the exemplary configuration shown.

As generally discussed above, an internal combustion engine consistent with the present disclosure may include a combustion chamber, which may be fluidly coupled with a first cylinder and a second cylinder. Also as generally discussed, the combustion chamber may be fluidly coupled with the first cylinder and the second cylinder such that the first cylinder may be at least partially fluidly coupled with the second cylinder. In some embodiments, the combustion chamber may at least partially surround the distal end of the first cylinder and/or the second cylinder. In some particular embodiments, the combustion chamber may cover at least a portion of the distal end of the first cylinder and/or the second cylinder.

In an illustrative example embodiment consistent with the present disclosure, the combustion chamber may include a cavity covering at least a portion of the first cylinder and at least a portion of the second cylinder. For example, and with reference to the example embodiment shown in fig. 7, the internal combustion engine 10b may include a combustion chamber 40b, which may be disposed at a distal end of the first and

second cylinders

14b, 18 b. Further, as shown, the combustion chamber 40b may cover and at least partially and/or completely surround the first cylinder 14b and the second cylinder 18. In some embodiments, as shown in the illustrated example embodiment, the combustion chamber may include a cavity that may be formed in a cylinder head 26b of the internal combustion engine 10, for example, which may be bolted or otherwise coupled with the engine block 24 b. In some embodiments, at the maximum reciprocation of the piston (e.g., at top dead center of crankshaft rotation), the piston may be adjacent to the distal ends of the first and

second cylinders

14b, 18 b. Thus, most and/or all of the fuel-air mixture drawn into the engine may be compressed within combustion chamber 40 b.

Consistent with some embodiments, the combustion chamber may be substantially symmetrical across the first cylinder and the second cylinder. For example, as generally shown in fig. 7, combustion chamber 40b may include a first cavity that may generally cover at least a portion of the first cylinder and at least a portion of the second cylinder. Further, in some embodiments, the combustion chamber may cover a substantial portion of the first and

second cylinders

14a, 18a, and may form a cavity over the distal ends of the first and second cylinders. Although the illustrated combustion chamber 40b has a generally rectangular configuration, it should be understood that the geometry of the combustion chamber may vary. For example, the combustion chamber may have a generally circular shape, such as a generally elliptical or hemispherical shape, e.g., including rounded and/or smoothly contoured corners. Further, as shown, for example, in the exemplary embodiment shown in FIG. 18, the combustion chamber may be asymmetric over the first cylinder and the second cylinder. In some such embodiments, the combustion chamber may define a different relative depth or volume in the area overlying the first cylinder relative to the area overlying the second cylinder.

In some embodiments consistent with the present disclosure, the combustion chamber may include a first cavity portion at least partially covering at least a portion of the first cylinder and a second cavity portion at least partially covering at least a portion of the second cylinder. For example, and with reference to the illustrative example embodiment shown in FIG. 3, the combustion chamber 40a may define a first cavity 42 that substantially covers the first cylinder 14a, and may define a second cavity 44 that substantially covers the second cylinder 18 a. As shown, the first and

second cavities

42, 44 may be at least partially separated from one another. Further, in some such embodiments, the first and second cavities may be in fluid communication with each other. For example, in some embodiments, the separation between the first and second cavities may not extend completely to the engine block, thereby providing at least partial fluid communication between the first and second cavities. Further, in some embodiments consistent with the present disclosure, the first and second cavities may be in fluid communication with each other in the region of one or more of the intake and exhaust valves. Consistent with the foregoing example, in this example, the combustion chamber may generally include a first cavity and a second cavity, and fluid communication between the first cavity and the second cavity may facilitate one or more of facilitating a simultaneous flow of a fuel-air mixture into both the first cavity and the second cavity through the intake valve, facilitating a spread of combustion of the fuel-air mixture throughout the first cavity and the second cavity and/or facilitating a spread of combustion of the fuel-air mixture from the first cavity to the second cavity, and/or facilitating a flow of combustion products from the first cavity and the second cavity out through the exhaust valve.

Consistent with some embodiments of the present disclosure, an ignition source may be at least partially disposed within the combustion chamber. For example, as shown in fig. 3, the ignition source may include a spark plug 46a, which may be at least partially disposed within the combustion chamber 40a to ignite the fuel-air mixture therein. In some embodiments, the spark plug may protrude into the combustion chamber. In some embodiments, a spark plug may be at least partially disposed in a recess in a wall of the combustion chamber, which may provide fluid communication between the combustion chamber and the spark plug, for example, to allow the spark plug to ignite a fuel-air mixture within the combustion chamber. Consistent with some illustrative example embodiments, an internal combustion engine may include a single spark plug that may ignite a fuel-air mixture within a combustion chamber.

Referring to the illustrative example embodiment shown in FIG. 7, internal combustion engine 10b may include a single spark plug 46b for igniting the fuel-air mixture within combustion chamber 40 b. When spark plug 46b ignites the fuel-air mixture within combustion chamber 40b, combustion may spread from the ignition point throughout the combustion chamber. Further, consistent with embodiments in which the combustion chamber may include a first cavity associated with a first cylinder and a second cavity associated with a second cylinder (e.g., as shown in the illustrative example embodiment shown in fig. 3), fluid communication between the first cavity (e.g., cavity 42) and the second cavity (e.g., cavity 44) may allow the combustion process to propagate between the two cavities. In this regard, in embodiments that include a single spark plug (which may be associated with only one cavity, for example), ignition of the fuel-air mixture in the combustion chamber (i.e., in both cavities) may be ignited and/or ignition of the fuel-air mixture may propagate through both cavities.

Further, in some illustrative example embodiments, the internal combustion engine may include two ignition sources. For example, a first ignition source (e.g., a spark plug) may be generally associated with a first cylinder and a second ignition source (e.g., a spark plug) may be generally associated with a second cylinder. In some such embodiments, the inclusion of multiple ignition sources may facilitate rapid ignition of the fuel-air mixture and/or may facilitate complete and/or rapid combustion of the fuel-air mixture. Referring to the illustrative example embodiment shown in fig. 3, in some embodiments, for example, where combustion chamber 40a may include first and

second cavities

42, 44, internal combustion engine 10a may include a first ignition source 46a associated with one of the cavities (e.g., second cavity 44 in the illustrated embodiment) and a second ignition source 48 associated with the other cavity (e.g., first cavity 42 in the illustrated embodiment). Consistent with some such embodiments, and as generally discussed above, the inclusion of two ignition sources may facilitate rapid and/or complete combustion of a fuel-air mixture within a combustion chamber (e.g., which may be at least partially partitioned into a first cavity and a second cavity).

As generally described above, an internal combustion engine consistent with the present disclosure may include an intake valve (and/or more than one intake valve) that may provide selective fluid communication between an intake system and a combustion chamber. For example, the intake valve may be in fluid communication with the combustion chamber (e.g., in embodiments including multiple combustion chamber cavities, may include fluid communication with first and second cavities of the combustion chamber, as generally described above) and/or with both the first and second cylinders. Generally, the air intake system may include one or more of a fuel source and an air source, and may at least partially facilitate mixing and/or atomization of the fuel in the air. Examples of intake systems may include, but are not limited to, carburetors, fuel injection systems, intake runners, intake manifolds, and the like. Consistent with some such embodiments, a fuel-air mixture, such as provided by a carburetor, may enter the combustion chamber through an intake valve (or more than one intake valve). As is well known, selective fluid communication between the intake system and the combustion chambers may be achieved by, for example, opening intake valves to charge one or more of the cylinders and/or the combustion chambers with a fuel-air mixture at least during an intake cycle of the internal combustion engine.

Similarly, and as generally described above, an internal combustion engine consistent with the present disclosure may also include an exhaust valve (and/or more than one exhaust valve) that may provide selective fluid communication between an exhaust system and a combustion chamber. For example, the exhaust valve may be in fluid communication with the combustion chamber (e.g., in embodiments including multiple combustion chamber cavities, may include fluid communication with first and second cavities of the combustion chamber, as generally described above) and/or with both the first and second cylinders. Generally, an exhaust system may include, for example, an exhaust runner, an exhaust manifold, a muffler, and/or one or more emission control devices (e.g., an exhaust gas recirculation system, a catalytic converter, etc.). The exhaust system may generally allow for the extraction of combustion products of the fuel-air mixture from one or more of the combustion chamber (including first and second combustion chamber cavities in embodiments including multiple combustion chamber cavities), the first cylinder, and/or the second cylinder. Selective fluid communication between the exhaust system and the combustion chamber (and/or the first and second cylinders) may be provided by, for example, opening an exhaust valve during at least an exhaust cycle of the internal combustion engine.

Consistent with the present disclosure, a wide variety of intake and exhaust valve arrangements may be implemented with respect to cylinder arrangements. For example, and referring generally to fig. 19-23, some non-limiting examples of valve arrangements and cylinder arrangements are schematically illustrated. In accordance with the schematically illustrated valve arrangement, the center line 50 of the crankshaft extends vertically in the drawing. As will be discussed in more detail below, the intake and exhaust valves may be configured in an overhead valve arrangement (e.g., where the intake and exhaust valves are at least partially disposed in the cylinder head and may open and close ports in the combustion chamber), and/or may be configured in a flathead valve arrangement (e.g., where the intake and exhaust valves may be at least partially disposed in the engine block and may open and close ports in the engine block). Thus, it should be understood that the valve arrangements schematically shown may be equally applicable to both flathead engine configurations and overhead valve configurations. Further, it should be appreciated that, particularly with respect to overhead valve configurations, the schematically illustrated valves may at least partially cover one or more of the first and second cylinders. Additionally, it should be appreciated that while the various schematically illustrated valve arrangements are shown in the context of a first cylinder and a second cylinder having substantially similar diameters, the schematically illustrated valve arrangements are equally applicable to internal combustion engine embodiments in which the diameter of the first cylinder may be different than the diameter of the second cylinder.

Referring to FIG. 19, an illustrative example of a four valve configuration of an internal combustion engine having a parallel inline cylinder configuration is shown. As shown, the valves may generally be configured with two intake valves 52 and two exhaust valves 54, which are generally disposed on opposite sides of the

cylinders

14, 18. Further, as generally illustrated, each cylinder may include a respective intake valve and exhaust valve that are each laterally opposite an approximate centerline of each respective cylinder.

Referring to FIG. 20, another illustrative example of a four valve configuration of an internal combustion engine having a parallel inline cylinder configuration is shown. As shown, the valves may generally be configured with two intake valves 52 and two exhaust valves 54 disposed on either side of the

cylinders

14, 18. Consistent with the illustrative example embodiment, valves may be generally disposed about the partition between the two

cylinders

14, 18.

Referring to FIG. 21, an illustrative example embodiment of a two valve configuration for an internal combustion engine having a parallel inline cylinder configuration is shown. In the illustrated example embodiment, intake valve 52 and exhaust valve 54 may be disposed on the same side of the cylinder. Although in the illustrated example embodiment, the intake and exhaust valves are shown as being generally aligned with the lateral centerlines of the two cylinders (e.g., with respect to centerline 50 of the crankshaft), in other configurations, the intake and exhaust valves may be placed closer to one another, e.g., in a separation region between the cylinders, similar to the configuration of the intake or exhaust valves shown in the example embodiment of FIG. 20.

Referring to FIG. 22, an illustrative example embodiment of a dual valve configuration for an internal combustion engine having an offset valve cylinder arrangement (i.e., a cylinder arrangement in which the vertical centerlines of two cylinders are offset to either side of the centerline 50 of the crankshaft, respectively) is shown. As shown, the intake valve 52 and the exhaust valve may be offset relative to each other in a "pocket" between the two cylinders along the centerline 50 of the crankshaft. It should be appreciated that in some embodiments, the intake and exhaust valves may be placed closer together toward the centerline 50 of the crankshaft.

Referring to FIG. 23, an illustrative example embodiment of a two valve configuration for an internal combustion engine having a parallel inline cylinder configuration is shown. Consistent with the configuration shown, the intake and exhaust valves may be generally in-line with each other and transverse to a centerline 50 of the crankshaft, and the centerline between the intake and exhaust valves may be generally centered between the two

cylinders

14, 18. In some embodiments, such a configuration may provide for reduced lateral expansion of the valve and/or may provide for a relatively small combustion chamber footprint (i.e., the plan view area of the combustion chamber at the interface between the cylinder head and the engine block).

As generally discussed above, consistent with various embodiments of the present disclosure, an internal combustion engine may be provided that may include intake and exhaust valves arranged in an overhead valve arrangement. For example, as generally shown in the illustrative example embodiments of fig. 3-4, 7-8, 11-12, and 18, intake and exhaust valves may be generally disposed within a cylinder head and may be actuated by way of a pushrod acting on a rocker assembly. For example, as shown in FIG. 4, intake valve 52a and exhaust valve 54a may be disposed in cylinder head 26 a. The intake valve 52a may be actuated, for example, by a rocker 56a, which may in turn be actuated by a pushrod 58a actuated by a cam (not shown) that is actuated, directly or indirectly, by the crankshaft 20a (thereby ensuring desired valve timing relative to piston motion). Thus, when the cam acts on the pushrod 58a, the pushrod 58a may actuate the rocker 56a, which may actuate the intake valve 52, causing the valve to open (and subsequently close based on the cam profile and rotation of the cam). A corresponding arrangement for actuating (e.g., opening and closing) the exhaust valve may be implemented. Consistent with such embodiments, a pushrod (e.g., pushrod 58a) may extend through the rod gallery 60a, through the engine block 24a, and to the cylinder head 26 a.

Consistent with some embodiments of the present disclosure, the intake and exhaust valves may be arranged in a flat head configuration. Consistent with such embodiments, intake and exhaust valves may be disposed in an engine block, rather than in a cylinder head and having opening and closing ports in the cylinder head and/or combustion chamber, and may open and close intake and exhaust ports disposed at least partially in the engine block. Consistent with such embodiments, the combustion chamber may at least partially cover the intake and exhaust valves, e.g., to provide open clearance and fluid communication between the valves and the combustion chamber and/or one or more of the first and second cylinders. For example, and still referring to FIG. 24, an illustrative example embodiment of an internal combustion engine 10d including a flat head configuration is schematically shown. As shown in the illustrated embodiment, the internal combustion engine 10d may include an engine block 24d including a first cylinder 14d and a second cylinder 18d, each including an associated piston (12d, 16 d). The engine block 24d may also include ports (e.g., intake port 62d, which may provide fluid communication with an intake system) and valves (e.g., intake valve 52 d). As shown, the cylinder head 26d may include a combustion chamber 40d that may at least partially cover the intake valve 52d and at least partially cover the first cylinder 14d and the second cylinder 18d, thereby providing an open gap for the intake valve 52d and selective fluid communication between the intake system (via the intake port 62d) and the combustion chamber 40 d. The selective opening and closing of intake valve 52d may be accomplished by a cam (not shown) that is driven directly or indirectly by a crankshaft acting on a valve stem. It should be appreciated that the exhaust valve may include a similar arrangement to provide selective fluid communication between the exhaust system and the combustion chamber.

As generally discussed above, the valves may be driven by a cam (acting directly on the valve stem and/or indirectly through a pushrod and rocker assembly), which may be driven directly or indirectly by the crankshaft to provide selective opening and closing of the valves in coordination with the reciprocating motion of the pistons. Consistent with the present disclosure, various valve actuation devices may be used to selectively open and close valves. FIGS. 25-33 show various non-limiting illustrative example embodiments of valve actuation devices that may be used in conjunction with the present disclosure. In the illustrative example embodiment shown, a direct valve actuation device is shown in which the valves are directly actuated by pushing on the valve stems. Such an arrangement may be used in conjunction with a flat head valve arrangement (e.g., as shown in fig. 24). It should be understood, however, that such a configuration may be equivalently used in conjunction with overhead valve arrangements, wherein the cam may act on a pushrod instead of a valve stem, and the pushrod may in turn act on a rocker assembly that may actuate the valve, as generally shown in fig. 3-4, 7-8, 11-12, and 18. Thus, it should be appreciated that the exemplary valve actuation devices shown may be used in conjunction with flathead engine configurations as well as with overhead valve engine configurations.

Referring to FIG. 25, an illustrative example embodiment of a direct actuation configuration is shown in which the camshaft 64 is oriented transverse to and rotated by the crankshaft 20. In such a configuration, the camshaft 64 and the crankshaft 20 may include cooperating helical gears that may allow for transverse arrangement of the camshaft and crankshaft, and may allow the camshaft to rotate at the rate of the crankshaft (e.g., to provide desired timing for a four-cycle combustion process). A similar camshaft-crankshaft drive is also shown in fig. 26 to 28. As shown in FIG. 25, the intake and exhaust valves may be directly actuated by respective cams (e.g., the stem of intake valve 52 may be actuated by cam 70) to achieve the desired opening and closing of the intake valve. Corresponding arrangements may be utilized for opening and closing the exhaust valve.

Referring to fig. 26, an illustrative example embodiment of an indirect actuation configuration is shown. Consistent with the arrangement shown, the camshaft may be oriented transverse to the crankshaft, as generally described above. The intermediate lever 72 may ride on the cam rather than the cam acting directly on the valve (e.g., via the valve stem). The lever 72 may include a pivot 74 such that the lever 72 may ride on the cam 70 and may pivot in response to rotation of the cam and cam profile. Consistent with an exemplary arrangement, the valves (or pushrods) may be laterally separated from the centerline of the camshaft. In some embodiments, the lever may provide a mechanical advantage, for example, allowing the cam to be lifted to a greater or lesser extent than the lift provided by the cam profile.

Referring to fig. 27, another illustrative example embodiment of an indirect actuation configuration is shown. Similar to the previous example embodiment, the example embodiment shown in fig. 27 may utilize a lever 76 that includes two arms, each arm having a respective pivot 78. Consistent with the configuration shown, the lever may be configured to actuate two valves (e.g., which may facilitate a four-valve engine configuration in which two valves are actuated from a single cam). Additionally, as with the previous example embodiments, the lever arrangement may allow the valve or pushrod to be displaced laterally to either side of the camshaft centerline and may provide a mechanical advantage that may provide greater or lesser valve lift than that provided by the cam profile.

Referring to fig. 28, another illustrative example embodiment of an indirect actuation configuration is shown. Similar to the previously illustrated example embodiments, a lever may be used to actuate two (or more) valves via a single cam. In the example embodiment shown, the lever may include a wire form 80, i.e., a wire that has been bent into a desired shape. In addition to the previously noted features, the use of an indirect actuator in the form of a wire may provide a component that is relatively easy and/or inexpensive to manufacture. Additionally, in some embodiments, the wire form lever may provide a degree of elasticity and/or compliance, which may facilitate assembly (e.g., the wire form may elastically deform to allow insertion of the pivot arm into the corresponding pivot hole).

Referring to fig. 29-33, various valve actuation devices are shown including a single camshaft or a dual camshaft oriented parallel to the crankshaft. For example, as shown, the camshaft 82 may be oriented generally parallel to the crankshaft 20 and may be driven by the crankshaft via cooperating gears 84, 86, a belt, a chain, or the like. Consistent with the exemplary embodiment shown in fig. 29, the valves (or pushrods) may be indirectly actuated via levers 88, as generally discussed above with respect to the transverse camshaft arrangement. It will be appreciated that the lever may have a similar configuration to any of the previously discussed levers and may provide similar features and advantages.

Referring to fig. 30-32, a variety of direct actuation configurations are shown in which valves (or pushrods) may be directly actuated by cams disposed on a camshaft oriented generally parallel to the crankshaft. For example, consistent with the embodiment shown in FIG. 30, a single camshaft may include two cams that may actuate respective valves. In the illustrated embodiment, the two cams may have different profiles and/or different clocks, with one cam actuating the intake valve and the other cam actuating the exhaust valve. Consistent with the example embodiment shown in FIG. 31, two camshafts may be used, one for actuating the intake valves and one for actuating the exhaust valves. As shown, each camshaft may include two cams to actuate two respective valves (i.e., the intake camshaft may actuate two intake valves and the exhaust camshaft may actuate two exhaust valves). Referring to FIG. 32, in a similar embodiment, two camshafts may be utilized, one for actuating the exhaust valves and one for actuating the intake valves. As shown, each camshaft may include a single cam for actuating a single valve, for example, a single cam as may be used in a two-valve internal combustion engine.

Referring to FIG. 33, an illustrative example embodiment of an axial cam device is shown. Consistent with the illustrated embodiment, the camshaft may be disposed substantially perpendicular to the crankshaft and may be driven by cooperating

bevel gears

90, 92, helical gears, or the like. As shown, the camshaft may be generally oriented in the intended direction of valve motion. The camshaft may include an axial cam, which may include a cam plate oriented substantially perpendicular to an axis of the camshaft. The cam plate may include a contoured face (e.g., at least a portion of which may be angled relative to a plane of rotation of the cam plate). As shown, the valves (or pushrods) may be radially displaced from the longitudinal axis of the camshaft. As the camshaft rotates the cam plate, the contoured surfaces of the cam plate may cause the valves to lift and retract, resulting in the opening and closing of the valves. As with conventional cams, a cam profile around the contact surface between the cam plate and the valve stem (or pushrod) may control the lift and closing of the valve.

While various examples of cam devices have been shown, various additional and/or alternative configurations may also be utilized, as described above. Further, as generally mentioned throughout, while the illustrated embodiments relate to actuation of the valves themselves, it should be appreciated that various cam devices may be utilized to actuate a pushrod, which may actuate the valve, such as through a rocker assembly or other suitable device.

As generally discussed above, consistent with some embodiments, the present disclosure may provide a multi-cylinder internal combustion engine that may include one or more ignition cylinders and corresponding pistons (i.e., cylinders that may at least partially intake a fuel-air mixture, compress the fuel-air mixture, generate power through combustion of the fuel-air mixture, and exhaust combustion products of the fuel-air mixture). Additionally, in some embodiments consistent with the present disclosure, an internal combustion engine may include one or more cylinders and corresponding pistons, which may perform additional functions related to one or more aspects of the operation of the internal combustion engine. For example, in some embodiments, one or more cylinders and associated pistons may pressurize a fluid that may be selectively released to start and/or assist in starting the internal combustion engine.

Continuing with the foregoing, some embodiments consistent with the present disclosure may include an internal combustion engine (e.g., may be a four-stroke air-cooled internal combustion engine and/or another type of internal combustion engine, as previously described) that may include a first piston reciprocally disposed in a first cylinder and a combustion chamber fluidly coupled with the first cylinder. The internal combustion engine may also include an ignition source, which may be at least partially disposed within the combustion chamber. An intake valve may provide selective fluid communication between the intake system and the combustion chamber, and an exhaust valve may provide selective fluid communication between the exhaust system and the combustion chamber. The second piston may be reciprocally disposed within the second cylinder, wherein reciprocation of the second piston may draw fluid into the second cylinder through the fluid inlet and may expel fluid from the second cylinder through the fluid outlet. The accumulator may be fluidly coupled with the fluid outlet of the second cylinder to receive fluid from the second cylinder and provide a reservoir of pressurized fluid. The crankshaft may be coupled with the first and second pistons for rotational motion associated with reciprocating motion in the first and second pistons.

For example, and still referring to fig. 34-37, an illustrative example embodiment of an internal combustion engine 100a is shown. As shown, the internal combustion engine 100a may include an air-cooled engine (e.g., including one or more cooling features, such as fins). As generally described in connection with the previous embodiments, the internal combustion engine may include a first piston 102a reciprocally disposed in a first cylinder 104a and a combustion chamber 106a fluidly coupled with the first cylinder 104 a. Consistent with the example embodiment shown, the first cylinder 104a may include an ignition cylinder. While the illustrated example embodiment is shown as including a single firing cylinder, it should be appreciated that an internal combustion engine may include more than one firing cylinder. Consistent with such embodiments, the plurality of firing cylinders may be configured in the manner of an internal combustion engine consistent with the principles and embodiments described above, and/or may be configured in the manner of any conventional multi-cylinder internal combustion engine. Additionally, the internal combustion engine 100a may include an ignition source 108a, which may be disposed at least partially within the combustion chamber 106 a. Consistent with some example embodiments, the ignition source may include a spark plug.

Continuing with the example embodiment shown, the internal combustion engine may additionally include an intake valve 110a that may provide selective fluid communication between an intake system (e.g., which may include one or more of a carburetor and/or a fuel injection system, an intake runner, and/or an intake manifold) and the combustion chamber 106 a. Further, the internal combustion engine may include an exhaust valve 112a that provides selective fluid communication between an exhaust system (e.g., which may include one or more of an exhaust runner, an exhaust manifold, and/or a muffler) and the combustion chamber 106 a. Together, the intake and exhaust valves may allow a fuel-air mixture to be drawn into the first cylinder and/or combustion chamber and compressed (e.g., by the reciprocating motion of the first piston). The compressed fuel-air mixture may be ignited by an ignition source that may reciprocally drive the first piston to generate power. Further, exhaust valves may allow products of combustion of the fuel-air mixture to be exhausted from the first cylinder and/or the combustion chamber. It should be appreciated that although a single intake valve and a single exhaust valve are shown, in some embodiments, the internal combustion engine may include more than one intake valve and/or more than one exhaust valve. Further, it should be appreciated that the intake and exhaust valves may be selectively opened and closed via, for example, one or more cams that may be rotationally driven, either directly or indirectly, by the crankshaft. Actuation of the valves may be in accordance with any of the previously described arrangements.

With continued reference to fig. 33-37, consistent with the example embodiment shown, the internal combustion engine 100a may include a second piston 114a that may be reciprocally disposed within a second cylinder 116 a. The reciprocating motion of the second piston 114a may draw fluid into the second cylinder 116a through the fluid inlet 118a and may expel fluid from the second cylinder 116a through the fluid outlet 120 a. Consistent with the example embodiment shown, the second cylinder 116a may be at least partially included in an engine block 122a of the internal combustion engine 100 a. In some such embodiments, the second cylinder 116a may be arranged in a parallel inline configuration with the first cylinder 104a and/or in an offset configuration with the first cylinder (e.g., in a manner generally described with respect to the multi-cylinders of the various previous embodiments). Additionally, the diameters of the second cylinder and the second piston may be substantially the same as the diameters of the first cylinder and the first piston (respectively). Further, in some embodiments, the diameters of the second cylinder and the second piston may be different (e.g., smaller or larger) than the diameters of the first cylinder and the first piston (respectively). Referring at least to fig. 38, in some embodiments consistent with the present disclosure, an internal combustion engine 100b may be provided in which a first piston 102b and a first cylinder 104a may be disposed within an engine block 122b, while a second piston and a second cylinder may be disposed in a separate structure 124b, which may be adjacent to, attached to, and/or integrated with the engine block 122b, and/or may be separate from the engine block 122b, for example.

The accumulator 126a may be fluidly coupled with the fluid outlet 120a of the second cylinder 116a to receive fluid from the second cylinder 116a and provide a reservoir of pressurized fluid. For example, as generally described, the second piston 114a may be reciprocally driven within the second cylinder 116a, which may result in fluid being drawn in through the fluid inlet 118a and expelled through the fluid outlet 120 a. In this regard, the fluid discharged from the fluid outlet 120a may have a greater pressure than the fluid at the fluid inlet 118 a. Further, the assembly of the second piston within the second cylinder (e.g., which may be provided by relative tolerances of the piston and cylinder and/or may be aided by features such as a compression ring on the piston) may minimize leakage of fluid flowing past the second piston and allow pressure to build up in the fluid being discharged from the second cylinder.

Furthermore, the fluid inlet and fluid outlet of the second cylinder may comprise e.g. check valve means, which may further assist in generating pressure within the accumulator. For example, as shown in fig. 39 and 40, and as is well known, the check valve arrangement may include a reed valve 128 (fig. 39), wherein one or more flexible reeds may be associated with respective inlet and outlet openings. The flexible reed can bend or flex to allow fluid to flow through the opening in one direction and can seal against the opening to prevent fluid from flowing through the opening in the other direction. In some embodiments, the check valve arrangement may include a ball check valve arrangement 130 (fig. 40) in which a ball is movably sealed in a corresponding seat. The ball may be separable from the seat to allow fluid flow in one direction and may seal against the seat to prevent fluid flow in another direction. It should be understood that a wide variety of additional and/or alternative check valve arrangements may be implemented, such as poppet valves and the like. Accordingly, the present disclosure should be understood to include all such additional and/or alternative check valve arrangements.

Consistent with some example embodiments, the fluid may comprise a compressible fluid, and accumulator 126a may comprise a pressure vessel. For example, an accumulator may include any vessel defining an internal volume that may receive a compressible fluid, the pressure inside the vessel increasing as additional compressible fluid is pumped into the pressure vessel. In some embodiments, the pressure buildup may be a function of the compressibility of the fluid. In some particular example embodiments, the compressible fluid may include air (e.g., such as ambient air surrounding the internal combustion engine 100a, which may be drawn into the inlet 118a associated with the second cylinder 116 a).

In some embodiments consistent with the present disclosure, the fluid may comprise a generally incompressible fluid (e.g., a liquid, although somewhat compressible, generally considered incompressible as compared to, for example, a gas). The incompressible fluid may include, but is not limited to, engine oil, hydraulic fluid, coolant, and the like. Consistent with such embodiments, the accumulator may include a pressure tank. As is known, a pressure tank may comprise a variable volume container that may be pushed towards a smaller first volume by a compressible medium and may be expanded to a larger second volume (comprising a plurality and/or infinitely variable volumes between the first and second volumes) by compressing the compressible medium in dependence on the fluid pressure in the variable volume container. For example, and referring to FIG. 41, an illustrative example embodiment of a pressure tank 132 is schematically shown. As shown, the pressure tank 132 may include a variable volume 134 and a compressible medium 136, such as a gas (e.g., air). The variable volume 134 may be separated from the compressible media 136 by, for example, a flexible and/or elastomeric membrane 138. As fluid enters the variable volume 134 (e.g., through the inlet 140), the pressure of the fluid in the variable volume may act on the membrane 138 to exert pressure on the compressible media 134, causing the compressible media to compress to a reduced volume, thereby increasing the volume of the variable volume 134. Additionally, the compressed compressible media may act on the membrane 138 to pressurize the fluid in the variable volume 134. Consistent with related embodiments, as shown in fig. 42 and 43, the variable volume may be provided by a flexible and/or elastic bladder 142 surrounded by a compressible medium. Further, in another embodiment, as shown in FIG. 43, the compressible media may include a spring 146 (and/or another compressible media, such as a gas) that may act on a flexible or resilient membrane, a plunger 144, or the like. It should be appreciated that various additional and/or alternative devices may be utilized to accumulate pressurized fluid (including incompressible fluid). Although the use of a pressure tank is generally described in connection with the use of an incompressible fluid, it should be understood that a pressure tank may similarly be used in connection with a compressible fluid such as air.

Consistent with the present disclosure, the internal combustion engine may include a crankshaft 148 that may be coupled with the first and second pistons for rotational motion associated with the reciprocating motion of the first and second pistons. As generally described above, in some embodiments, crankshaft 148 may be coupled with first piston 102a such that rotational motion of the crankshaft causes reciprocation of the first piston, and reciprocation of the first piston causes rotation of the crankshaft. Further, crankshaft 148 may be coupled with second piston 114a such that rotational motion of the crankshaft causes reciprocating motion of the second piston. In some embodiments, the second piston may be coupled with the crankshaft such that reciprocating motion of the second piston causes rotation of the crankshaft.

For example, in some embodiments, the crankshaft may be coupled to the first piston by a first crank journal and may be coupled to the second piston by a second crank journal, as generally described in connection with the previous embodiments. As described in connection with the previous embodiments, the first and second pistons may be coupled with the crankshaft by a single crank journal and/or by two separate crank journals. Further, consistent with such embodiments, the connection of the first and second pistons to the one or more crank journals may utilize any of the connecting rod configurations previously described.

In some embodiments, the crankshaft 148 may be coupled to the first piston 102a via a first crank journal 150a, and may be coupled to the second piston 114a via a cam 152 a. Consistent with such an embodiment, rotation of the crankshaft (and thus the cam) may impart reciprocating motion on the second piston, causing fluid to be drawn into the second cylinder and discharged to the accumulator. In some embodiments, the internal combustion engine 100a may also include a return spring 154a associated with the second piston. The return spring 154a may be configured to maintain contact between a cam follower associated with the second piston and the cam. Consistent with various embodiments, the cam follower associated with the second piston may include a solid cam follower and/or a roller cam follower.

In some embodiments, the accumulator may include a fluid outlet in selective fluid communication with the rotary drive system for selectively rotationally driving the crankshaft. The selective rotational drive of the crankshaft may be used, for example, to start and/or assist in starting the internal combustion engine. Consistent with some such embodiments, a less powerful starting system (e.g., a smaller electric starter motor and/or a smaller starting battery) may be used, and/or an easier manual start may be achieved (e.g., by a recoil starting system or other manual starting system). Consistent with some such embodiments, an outlet associated with an accumulator (e.g., accumulator 126a in fig. 37) may include an outlet 156a and a selective valve 158 a. Although the outlet of the accumulator is shown as a different outlet relative to the inlet, it will be appreciated that in some embodiments the accumulator may comprise a combined inlet/outlet in which a T-shaped or branched connection provides a fluid coupling with the second cylinder and with the valve. Valve 158 may be selectively opened (e.g., during startup) to allow release of pressurized fluid from accumulator 126 a. The valve 158a may comprise an electronically actuated valve, a hydraulically actuated valve, a pneumatically actuated valve, a mechanically actuated valve, etc., which may be opened during start-up of the internal combustion engine. For example, in connection with an internal combustion engine having electric starting capability, actuating the start switch may open a valve in addition to actuating the starter motor, thereby allowing release of pressurized fluid from the accumulator. In conjunction with internal combustion engines having manual starting capabilities, actuating a starting mechanism (e.g., pulling a recoil starter) may open a valve, allowing pressurized fluid to be released from an accumulator. It should be appreciated that combinations of the foregoing may be utilized, for example, in conjunction with an internal combustion engine that includes both electric and manual starting capabilities.

With particular reference to the illustrative example embodiment shown in fig. 34-37, in some implementations, the rotary drive system may include a turbine 160 rotationally coupled with the crankshaft 148 a. For example, as shown in fig. 37, an outlet 156a of accumulator 126a may include a nozzle arranged to direct a release of pressurized fluid (e.g., which may include pressurized air) to impinge turbine 160 in a manner that causes the turbine and, thus, the crankshaft to rotate. Consistent with the illustrated embodiment, the turbine may be mounted directly to the crankshaft. In other embodiments, the turbine may be separately rotationally mounted and may be indirectly coupled with the crankshaft (e.g., through a gear train, belt drive, chain drive, etc.). In some particular embodiments, the turbine may be rotationally coupled with the crankshaft through a gear train, for example, the gear train may provide torque multiplication between the turbine and the crankshaft. Such a configuration may, for example, convert a relatively high rotational speed of the turbine into a slower but higher torque rotation of the crankshaft. Further, in some embodiments, the turbine may be coupled with the crankshaft by an overrunning clutch, e.g., when the crankshaft speed is greater than the turbine speed, the overrunning clutch may allow the crankshaft to rotate independently of the turbine (accommodating any speed multiplication that may be provided by a gear train connecting the turbine and the crankshaft). In some such embodiments, parasitic power losses that may be caused by the internal combustion engine driving the turbine during operation of the internal combustion engine may be reduced and/or eliminated.

According to some example embodiments, the rotary drive system may include a hydraulic motor rotationally coupled with the crankshaft. For example, referring to fig. 44-47, an illustrative example embodiment of an internal combustion engine 100c is shown. The internal combustion engine 100c may generally correspond to the illustrative example internal combustion engine 100 a. As shown, the internal combustion engine 100c may include a hydraulic motor 162 connected to an outlet of the accumulator 126 c. When the outlet of accumulator 126c is coupled with hydraulic motor 162 (e.g., by opening of valve 158 c), pressurized fluid (e.g., engine oil, hydraulic fluid, air, etc.) may flow through hydraulic motor 162, rotating a pulley 164 associated with the hydraulic motor. The pulley 164 may in turn rotate a crankshaft via a pulley 166. As discussed above with respect to the previous embodiments, in addition to or as an alternative to the illustrated belt drive configuration, the hydraulic motor may be coupled directly with the crankshaft, may be coupled with the crankshaft through a gear train, may be coupled with the crankshaft through a chain drive, may include an overrunning clutch, and the like, as well as various combinations of such configurations.

Still referring to fig. 48, in some embodiments, for example, where the fluid may include engine oil, hydraulic oil, and/or another fluid other than air, after being released from accumulator 126c and passing through hydraulic motor 162, the fluid may be transferred to reservoir 168. As discussed, in some embodiments, the fluid may include engine oil. Consistent with such embodiments, the reservoir may include an oil reservoir, such as an engine crankcase. Further, in some such embodiments, the internal combustion engine may be designed with increased engine oil capacity to accommodate additional use of engine oil to operate the hydraulic motor. During operation of the internal combustion engine 100c, fluid from the reservoir 168 may be pumped into the second cylinder 116c and then to the accumulator 126 c. In some embodiments, the fluid system may include, for example, a bypass 170, which may allow fluid pumped from the second cylinder to return to the reservoir when a maximum desired pressure and/or volume of fluid within the accumulator is reached.

According to embodiments consistent with the present disclosure, an internal combustion engine may include a first piston reciprocally disposed in a first cylinder and a combustion chamber fluidly coupled with the first cylinder. The ignition source may be at least partially disposed within the combustion chamber. An intake valve may provide selective fluid communication between the intake system and the combustion chamber, and an exhaust valve may provide selective fluid communication between the exhaust system and the combustion chamber. As generally discussed above, the first piston and cylinder may comprise an ignition cylinder. Further, in some embodiments, the internal combustion engine may include more than one firing cylinder, as also generally discussed above. The internal combustion engine may additionally include a second piston that may be reciprocally disposed within the second cylinder. An inlet associated with the second cylinder may be fluidly coupled to the intake system, and an outlet associated with the second cylinder may be fluidly coupled to one or more of the first cylinder and the combustion chamber. The crankshaft may be coupled with the first and second pistons for rotational motion associated with reciprocating motion in the first and second pistons. According to such an embodiment, the second cylinder may draw air and/or a fuel-air mixture from the intake system and may pump it into the first cylinder, thereby increasing the fuel-air charge available for combustion by the first cylinder and/or increasing the pressure within the first cylinder and/or combustion chamber. In this regard, the second cylinder may provide the first cylinder with a form of forced-induction air, which may, in some embodiments, increase the power output provided by the first cylinder compared to what may be achieved with the first cylinder using natural aspiration.

Referring to fig. 49-53, an internal combustion engine 200a is generally shown. Similar to the previously described embodiments, the internal combustion engine 200a may comprise an air-cooled four-stroke engine, however, other implementations may be utilized as well as the previously described embodiments. In a manner similar to the previous embodiment, the internal combustion engine 200a may include a first piston 202a reciprocally disposed in a first cylinder 204a and a combustion chamber 206a fluidly coupled with the first cylinder. The ignition source 208a may be at least partially disposed within the combustion chamber 206 a. The intake valve 210a may provide selective fluid communication between an intake system (e.g., a carburetor, a fuel injection system, an intake runner, and/or an intake manifold) and the combustion chamber 206a, and the exhaust valve 212a may provide selective fluid communication between an exhaust system (e.g., an exhaust runner, an exhaust manifold, and/or a muffler) and the combustion chamber 206 a.

Consistent with some embodiments, the internal combustion engine 200a may additionally include a second piston 214a, which may be reciprocally disposed within a second cylinder 216 a. As generally discussed above, the second cylinder may have a diameter that is generally similar to the first cylinder, and/or may have a larger or smaller diameter than the first cylinder. The inlet 218a associated with the second cylinder 216a may be fluidly coupled to an intake system (e.g., the intake system 218a, which may include one or more of a carburetor, a fuel injection system, an intake runner, and/or an intake manifold as previously described), and the outlet 220a associated with the second cylinder may be fluidly coupled to one or more of the first cylinder 202a and the combustion chamber 206 a. For example, as shown in fig. 51, in one embodiment, the outlet 220a of the second cylinder 216a may include a fluid conduit (e.g., which may include, for example, a tube or other fluid passage extending between the second cylinder 216a and the combustion chamber 206 a), or may include a fluid passage formed within one or more of an engine block 222a and a cylinder head 224a of the internal combustion engine 200 a. Referring additionally to fig. 54, in an embodiment, an outlet associated with the second cylinder 216b may be fluidly coupled with a port 226b formed, for example, between the second cylinder 216b and the first cylinder 204b in an engine block of the internal combustion engine 200 b.

Consistent with some embodiments, the reciprocating motion of the second piston 214a may draw a fuel-air mixture from the intake system 218a into the second cylinder 216a and may expel the fuel-air mixture into one or more of the first cylinder 204a and the combustion chamber 206 a. For example, the second piston 214a may expel the fuel-air mixture into one or more of the first cylinder 204a and the combustion chamber 206a during a compression stroke of the first piston and/or at the end of an intake stroke of the first piston (e.g., after the intake valve 210a closes). Consistent with such embodiments, the fuel-air mixture forced into the first cylinder and/or combustion chamber by the second piston may have a decreasing tendency to force the fuel-air mixture drawn into the first cylinder by the first piston (e.g., during an intake cycle) out of the first cylinder and/or combustion chamber through an intake valve. That is, the naturally-drawn fuel-air mixture in the first cylinder and/or combustion chamber may be substantially maintained. In this way, the fuel-air mixture forced into the first cylinder and/or combustion chamber by the second piston may increase the amount of fuel-air mixture within the first cylinder and/or combustion chamber as compared to the amount of fuel-air mixture that would have been forced into the first cylinder and/or combustion chamber through the natural aspiration of the internal combustion engine 200 a. In this regard, operation of the second piston and the second cylinder may provide a degree of forced charge air intake. The forced charge provided by operation of the second piston and the second cylinder may increase the power output and/or another operating characteristic of the internal combustion engine, for example, relative to naturally aspirated air. It will be appreciated that the second piston may also expel the fuel-air mixture into the first cylinder and/or combustion chamber during the intake stroke and/or power stroke of the first piston, in addition to or instead of expelling the fuel-air mixture into the first cylinder and/or combustion chamber at the end of the intake stroke and/or during the compression stroke, for example depending on the pressures reached by the second piston and second cylinder.

According to some embodiments consistent with the present disclosure, the inlet associated with the second cylinder may include a check valve arrangement (e.g.,

check valves

228a, 228b) between the intake system and the second cylinder. As generally shown, and as described above, the check valve arrangement may include a reed valve, a ball check valve, a poppet check valve, or the like. Further, in some embodiments, the outlet associated with the second cylinder 216a may include a check valve arrangement (e.g., check valve 230a) between the second cylinder and one or more of the first cylinder 204a and the combustion chamber 206 a. In some embodiments, a check valve between the second cylinder and the first cylinder and/or combustion chamber may reduce and/or prevent combustion from spreading from the first cylinder and/or combustion chamber into the second cylinder (e.g., which may combust any residual fuel-air mixture within the second cylinder). In some embodiments, such as shown with respect to the internal combustion engine 200b shown in fig. 54, which may include a port 226b between the second cylinder 216b and the first cylinder 204b, the position of the first piston 202b may at least partially and/or completely block the port 226b during combustion, thereby preventing and/or reducing the spread of combustion from the first cylinder to the second cylinder.

In a manner similar to that described herein with respect to other embodiments, the internal combustion engine 200a may include a crankshaft 232a that may be coupled with the first and

second pistons

202a, 214a for rotational motion associated with the reciprocating motion of the first and

second pistons

202a, 214 a. For example, rotation of the crankshaft may result in reciprocation of the first piston, and reciprocation of the first piston may result in rotation of the crankshaft. Similarly, rotation of the crankshaft may result in at least reciprocation of the second piston. In some embodiments, the crankshaft 232a may be coupled with the first piston 202a by a first crank journal 234a and may be coupled with the second piston by a second crank journal, for example, as generally described above and shown in connection with various embodiments. Further, in some such embodiments, the first and second pistons may be coupled with respective first and second crank journals and/or may both be coupled with a single crank journal simultaneously. As previously described, various link configurations may be implemented.

In some embodiments consistent with the present disclosure, crankshaft 232a may be coupled with first piston 202a via first crank journal 234a and may be coupled with second piston 214a via cam 236 a. The cam 236a may be directly (as shown) and/or indirectly coupled with the crankshaft (e.g., may be located on a separate camshaft that may be rotationally coupled with the crankshaft). Thus, rotation of the cam 236a (due to rotation of the crankshaft 232 a) may reciprocally drive the second piston 214 a. As previously described, the second piston may interact with the cam via a solid cam follower and/or a roller cam follower. In some embodiments, a return spring 238a may be associated with second piston 214 a. The return spring 238a may be configured to maintain contact between a cam follower associated with the second piston 214a and the cam 236 a.

As generally shown, for example, in fig. 49, in some embodiments, the second cylinder 216a may be generally disposed in a housing 240a that may be adjacent to, attached to, and/or at least partially integrated with the engine block 222 a. Referring additionally to fig. 55, in some embodiments, the second cylinder 216c may be formed with and/or integrated within the engine block 222c along with the first cylinder 204 c. It should be understood that various additional and/or alternative configurations may be implemented.

In some embodiments consistent with the present disclosure, an internal combustion engine (including, but not limited to, an air-cooled four-stroke internal combustion engine) may include a first piston (and/or more than one piston) reciprocally disposed in a first cylinder (and/or more than one corresponding cylinder) and a combustion chamber fluidly coupled with the first cylinder. The ignition source may be at least partially disposed within the combustion chamber. An intake valve may provide selective fluid communication between the intake system and the combustion chamber, and an exhaust valve may provide selective fluid communication between the exhaust system and the combustion chamber. A second piston may be reciprocally disposed in the second cylinder. The crankshaft may be coupled with the first and second pistons for rotational motion associated with reciprocating motion in the first and second pistons. Consistent with such an embodiment, the second piston and the second cylinder may not be ignited (i.e., may not be exposed to combustion of the fuel-air mixture to generate power). In some such embodiments, the reciprocating motion of the second piston may impart vibrations, for example, on the internal combustion engine, which may, for example, at least partially cancel vibrations caused by the reciprocating motion of the first piston, combustion of the fuel-air mixture in the first cylinder and/or combustion chamber, rotation of the camshaft, and/or the like. In some embodiments, the reciprocating motion of the second piston may impart vibrations on the internal combustion engine that may at least partially adjust the vibration characteristics of the internal combustion engine (i.e., the vibration characteristics of the internal combustion engine may be altered relative to the vibration characteristics in the absence of the second piston).

For example, referring to fig. 56-59, an illustrative example embodiment of an internal combustion engine 250a may include a first piston 252a reciprocally disposed within a first cylinder 254a, and a combustion chamber 256a fluidly coupled with the first cylinder 254 a. The ignition source 258a may be at least partially disposed within the combustion chamber 256 a. Intake valve 260a may provide selective fluid communication between an intake system (e.g., which may include a carburetor, a fuel injection system, an intake runner, and/or an intake manifold) and combustion chamber 256a, and exhaust valve 262a may provide selective fluid communication between an exhaust system (e.g., which may include an exhaust runner, an exhaust manifold, and/or a muffler) and combustion chamber 256 a. As generally discussed above, the first cylinder may comprise an ignition cylinder, as the first piston may be exposed to combustion of a fuel-air mixture within the combustion chamber and/or the first cylinder to cause reciprocation of the first piston.

The internal combustion engine 250a may also include a second piston 264a, which may be reciprocally disposed within a second cylinder 266 a. Consistent with some embodiments, the second piston may include a reciprocating mass. For example, as shown in fig. 58, the second piston 264a may be generally configured as a cylindrical body to provide a reciprocating mass. As shown, the second piston 264a may be configured differently relative to the first piston 252 a. In some embodiments, the second piston may be configured substantially similarly to the first piston. For example, as shown in fig. 60, the second piston 264b may be configured substantially similarly to the first piston 252 b. For example, the second piston may comprise a piston ring or the like. In some such embodiments, configuring the second piston similar to the first piston may reduce the number of discrete components required for the internal combustion engine.

Continuing the foregoing, wherein the second piston may be configured as a reciprocating mass, in some embodiments, the reciprocating mass may at least partially counteract the reciprocating motion of the first piston. For example, in one embodiment, the second piston may be configured to reciprocate out of time with the first piston, e.g., such that when the first piston reciprocates in a first direction, the second piston may reciprocate in a second, generally opposite direction. In some embodiments, the motion of the second piston may reduce vibrations imposed on the internal combustion engine by one or more of the reciprocating motion of the first piston, the combustion of the fuel-air mixture in the combustion chamber and/or the first cylinder, and/or the rotation of the crankshaft.

Consistent with some embodiments, the reciprocating mass of the second piston may adjust the vibration characteristics of the internal combustion engine. For example, the reciprocating motion of the second piston may cause vibrations in the internal combustion engine. The frequency and amplitude of the vibration caused by the second piston may change the frequency and/or amplitude of other vibrations imparted on the internal combustion engine by one or more of the reciprocating motion of the first piston, the ignition of the combustion process, and/or the rotation of the crankshaft. By varying the frequency and/or amplitude of vibrations in the internal combustion engine, the internal combustion engine (and/or the piece of power equipment powered by the internal combustion engine) may exhibit a better sound and/or feel experienced by a user of the internal combustion engine or the piece of power equipment. It will be appreciated that the mass (e.g. including size and material) and frequency of reciprocation of the second piston may be selected to achieve the desired tuning effect.

Consistent with various embodiments, the second cylinder may be disposed and/or formed within an engine block 268a of the internal combustion engine 250a, which may also include the first cylinder 254 a. For example, as generally described above, the first and second cylinders may be arranged in a generally parallel inline configuration, an offset configuration, or the like. In some embodiments, the second cylinder may be disposed within a feature in the internal combustion engine that may be different from the engine block. For example, as shown in the illustrative example embodiment in FIG. 56, the second cylinder may be formed within a feature 270a, which may be adjacent to but distinct from the engine block 268 a. Further, in some embodiments, the second cylinder may be formed in a feature of the internal combustion engine that is not adjacent to the first cylinder. In some such embodiments, the second piston may be at least partially offset from the first piston. Further, in some embodiments, the second piston may be in a generally opposed configuration relative to the first piston. For example, and referring to the illustrative example embodiment shown in FIG. 60, the second cylinder 266b may be formed on an opposite side of the internal combustion engine 250b relative to the first cylinder 254 b. It should be understood that other configurations may be equivalently implemented. Additionally, as generally described herein, according to various embodiments, the first cylinder and the second cylinder may have substantially similar diameters, and/or the diameter of the second cylinder may be greater than or less than the diameter of the first cylinder.

The internal combustion engine 250a may additionally include a crankshaft 258a that may be coupled with the first and

second pistons

252a, 254a for rotational motion associated with the reciprocating motion of the first and second pistons. As described above, reciprocation of the first piston may cause rotation of the crankshaft, and rotation of the crankshaft may cause reciprocation of the first piston. Further, rotation of the crankshaft may cause at least reciprocation of the second piston. In some embodiments, the crankshaft may be coupled to the first piston by a first crank journal and may be coupled to the second piston by a second crank journal. For example, and referring to fig. 60, as shown, the crankshaft 258b may be coupled with the first piston 254b by a crank journal 272 b. Similarly, the crankshaft 258b may be coupled with the second piston 264b by a crank journal 272 b. In some embodiments, the first piston and the second piston may be coupled to the crankshaft by separate crank journals, as generally described above.

In some embodiments, the crankshaft may be coupled to the first piston by a first crank journal and may be coupled to the second piston by a cam. For example, and referring to fig. 58, the first piston 202a may be coupled with the crankshaft 258a via a crank journal 272a, and the second piston 264a may be coupled with the crankshaft 258a via a cam 274 a. The cam 274a may be rotated (directly and/or indirectly) by the crankshaft, which may reciprocate the second piston 264a within the second cylinder 266 a. In some embodiments, a return spring 276a may be associated with second piston 264a and may be configured to maintain contact between a cam follower associated with the second piston and cam 274 a. The cam follower associated with the second piston may comprise a solid cam follower and/or may comprise a roller cam follower.

Consistent with some embodiments, the second cylinder 266a may include a vent hole 278a that allows air to enter and exit the second cylinder during reciprocation of the second piston. Therefore, the reciprocating motion of the second piston may not be required to compress the air contained in the second cylinder. In some embodiments, the fitting between the second piston and the second cylinder may be loose enough to allow air (and/or another fluid) to pass between the side wall of the cylinder and the side wall of the piston, thereby reducing and/or eliminating the need for the piston to compress the air contained in the second cylinder.

Referring to FIG. 61, another illustrative example embodiment is shown generally. As shown, similar to the previous embodiment, an internal combustion engine 250c is shown that includes a non-firing second piston 264c, which may, for example, adjust the vibration characteristics of the internal combustion engine. Additionally, the internal combustion engine 250c may include a plurality of ignition cylinders (e.g., including

pistons

252c, 252d), which may generally be configured in any manner as discussed above. It should be understood that while the second piston 264c is shown as being disposed in an opposing configuration relative to the

ignition pistons

252c, 252d, other configurations, such as parallel inline and offset configurations relative to the ignition pistons, may be equally utilized.

Referring to fig. 61, a block diagram of a portion of an internal combustion engine 300 is shown. As is known, the internal combustion engine 300 may include an ignition cylinder 302 generally described above. Additionally, as is also well known and discussed above, the internal combustion engine 300 may generally include an intake system. The intake system may include, but is not limited to, an air filter 304 (e.g., at least a portion of particulate matter may be removed from the intake air), a carburetor 306 and/or a fuel injection system (e.g., fuel may be dispersed and/or atomized in the intake air to provide a fuel-air mixture), and/or an intake manifold 308 (e.g., which may include fluid conduits for directing the fuel-air mixture to the firing cylinders, and may include one or more conduits external to the engine and/or one or more fluid paths through a portion of the engine to intake valves of the firing cylinders). Similarly, the internal combustion engine 300 may include an exhaust system, which may include, but is not limited to, one or more of an exhaust manifold 310 (e.g., which may include one or more fluid conduits from exhaust valves through at least a portion of the fluid path of the engine or external to the engine) and/or a muffler 312 (e.g., which may reduce the volume of exhaust gas exiting the engine). The foregoing description is for completeness as the components of the intake and exhaust systems may be conventional and well known. In this regard, a detailed description is not necessary to understand the various components and features.

Various illustrative example embodiments have been described, each including various features, concepts and arrangements. It is to be understood that the features, concepts and arrangements disclosed in the context of one or several independent embodiments are susceptible to being applied in other embodiments and/or being combined with the features, concepts and/or arrangements discussed in relation to the various embodiments. Such combinations of features, concepts and arrangements from the several embodiments are expressly intended to fall within the scope of the disclosure herein.

Various features, advantages, embodiments, and examples have been described herein. It is to be understood, however, that the foregoing description and illustrated embodiments are for the purpose of illustration and explanation only and are not to be construed as limiting the invention. It is to be understood that the features and concepts associated with the various embodiments may be readily combined with the features and concepts of the other disclosed embodiments. In addition, it is to be understood that the concepts embodied by the description and illustrations are susceptible to variations and modifications, all of which are intended to be covered by the present invention.

Claims

1. An internal combustion engine, comprising:

a first piston reciprocally disposed in a first cylinder;

a second piston reciprocally disposed in a second cylinder;

a crankshaft coupled with the first and second pistons for rotational motion associated with reciprocating motion of at least one of the first and second pistons;

a combustion chamber fluidly coupled with the first cylinder and the second cylinder;

an ignition source disposed at least partially within the combustion chamber;

an intake valve providing selective fluid communication between an intake system and the combustion chamber; and

an exhaust valve providing selective fluid communication between an exhaust system and the combustion chamber.

2. The internal combustion engine of claim 1, wherein the crankshaft is configured to be disposed in a generally vertical orientation during operation.

3. The internal combustion engine of claim 1, wherein the first cylinder and the second cylinder are arranged in a parallel inline configuration.

4. The internal combustion engine of claim 1, wherein the first cylinder and the second cylinder are arranged in an offset configuration.

5. The internal combustion engine of claim 1, wherein the first cylinder and the second cylinder have substantially the same diameter.

6. The internal combustion engine of claim 1, wherein the first cylinder and the second cylinder have different diameters.

7. The internal combustion engine of claim 1, wherein the crankshaft is coupled with the first piston by a first crank journal and is coupled with the second piston by a second crank journal.

8. The internal combustion engine of claim 1, wherein the crankshaft is coupled with the first piston and the second piston by a first crank journal.

9. The internal combustion engine of claim 1, in which the combustion chamber includes a cavity covering at least a portion of the first cylinder and at least a portion of the second cylinder.

10. The internal combustion engine of claim 1, wherein the combustion chamber comprises:

a first cavity portion at least partially covering at least a portion of the first cylinder; and

a second cavity portion at least partially covering at least a portion of the second cylinder;

wherein the first cavity portion is at least partially separated from the second cavity portion.

11. The internal combustion engine of claim 1, wherein the ignition source comprises a spark plug.

12. The internal combustion engine of claim 11, wherein the ignition source includes a first spark plug associated with the first cylinder and a second spark plug associated with the second cylinder.

13. The internal combustion engine of claim 1, wherein the intake valve and the exhaust valve are arranged in an overhead valve configuration.

14. The internal combustion engine of claim 1, wherein the intake valve and the exhaust valve are arranged in a flat head configuration.

15. An internal combustion engine, comprising:

a first piston reciprocally disposed in a first cylinder;

a second piston reciprocally disposed in a second cylinder, the second piston having a diameter smaller than a diameter of the first piston, wherein the second piston is disposed vertically above the first piston during operation;

a crankshaft coupled with the first and second pistons for rotational motion associated with reciprocating motion of at least one of the first and second pistons, the crankshaft configured to be disposed in a generally vertical orientation during operation;

an ignition source disposed at least partially within the combustion chamber;

16. The internal combustion engine of claim 15, wherein the first cylinder and the second cylinder are formed in an engine block comprising a plurality of fins configured to provide air cooling of the internal combustion engine.

17. The internal combustion engine of claim 15, wherein the crankshaft is coupled with the first piston and the second piston by a first crank journal.

18. The internal combustion engine of claim 15, wherein the crankshaft is coupled with the first piston by a first crank journal and is coupled with the second piston by a second crank journal.

19. An internal combustion engine, comprising:

a first piston reciprocally disposed in a first cylinder, the first cylinder having a first diameter;

a second piston reciprocally disposed in a second cylinder having a second diameter substantially the same as the first diameter;

an ignition source disposed at least partially within the combustion chamber;

20. The internal combustion engine of claim 19, wherein the first cylinder and the second cylinder are formed in an engine block comprising a plurality of fins configured to provide air cooling of the internal combustion engine.