WO2015176649A1

WO2015176649A1 - A reciprocating internal combustion engine piston-cylinder-connecting rod assembly

Info

Publication number: WO2015176649A1
Application number: PCT/CN2015/079288
Authority: WO
Inventors: Stanley Moon Kai KO
Original assignee: Neo Mechanics Limited
Priority date: 2014-05-20
Filing date: 2015-05-19
Publication date: 2015-11-26
Also published as: TW201600772A; TWM519178U; TWI564494B

Abstract

Disclosed are a connecting rod (340) and a coil spring seal (1011) for sealing a piston-cylinder assembly in a reciprocating internal combustion engine. The connecting rod (340) is provided without leading to a large inertia for the connecting rod (340) while the connecting rod (340) is configured to withstand a large torque due to the misalignment among centers of a piston pin (630), a crank pin (640) and a crankshaft. The connecting rod (340) can be integrated with a piston (310) to form an assembly. The coil spring seal (1011) is configured to seal both the piston (310) and a cylinder in the piston-cylinder assembly. The coil spring seal (1011) has three layers (1012,1013,1014) of coil rings with different inner and outer diameters, providing a sealing function and an absorption of vibrations and lateral movements caused by the misalignments between the piston and the cylinder under high speed stroke motion. The helical structure (1001) of the coil spring seal (1011) generates a negligible friction on the sealing contact surface and reduces scratching on the cylinder internal wall. The sealing of both the piston (310) and the cylinder reduces seepage. The result is a cleaner engine with more efficient power output.

Description

A RECIPROCATING INTERNAL COMBUSTION ENGINE PISTON-CYLINDER-CONNECTING ROD ASSEMBLY

Claim for Priority:

This application claims priority under the Paris Convention to the U.S. Provisional Patent Application No. 62/000,577 filed May 20, 2014 and to the U.S. Provisional Patent Application No. 62/044,399 filed September 1, 2014, disclosures of which are incorporated herein by reference in their entirety.

Field of the Invention:

The present invention relates generally to the assembly of reciprocating engine piston-cylinder and connecting rod. In particular, the present invention relates to the connecting rods for connecting the pistons and crankshafts, and the sealing of pistons in cylinders.

Background of the Invention:

In a reciprocating internal combustion engine, an assembly of a connecting rod and a reciprocating engine piston is used to convert a lineal thrust to a rotational thrust. FIG. 1 depicts a conventional assembly that comprises a connecting rod 140 and a piston 110 connected thereto. The connecting rod 140 has an upper end 142 and a lower end 144 both arranged such that the upper end 142 is connectable to the piston 110 and the lower end 144 is connectable to a crankshaft. A piston pin is housed in a piston pin hole 148 and is used to connect the upper end 142 of the connecting rod 140 to the piston 110 at its piston skirt 114. A crank pin is housed in a crank pin hole 149 and is used for connecting the lower end 144 to the crankshaft.

In actual mechanical arrangements, the thickness of a connecting rod is far smaller than the diameter of a piston. In fact, the connecting rod does not need to have a long piston pin in order to be connected to the piston. However, due to misalignment of a crankshaft during assembling of the engine, or any shift of positions during the movement of the engine, huge torque forces are exerted on to the connecting rod. To release such torque forces as much as possible, clearances on both ends of the piston pin are provided in order that the upper end of the connecting rod can shift back and forth in position.

A connecting rod is generally rigid, dense, and heavy because it is designed to be pushed by the explosive power of fuel combustion through the piston and rotational thrusts of the crankshaft through a crank pin, and simultaneously, to endure the aforementioned torque forces constantly during the combustion cycle. Thus, the connecting rod is usually made by forging to achieve a high density for the highest possible strength.

When the upper end of the connecting rod shifts back and forth in high speed, it is like a hammer hitting the piston skirt with high frequency, pushing the piston head to press against the cylinder wall, scratching along the cylinder wall during upward and downward movements of the piston. It causes tremendous noise and severe vibration of the internal combustion engine. Fuel is wasted during the course of action.

FIG. 2A depicts an ideal situation of operating an internal combustion engine. In particular, FIG. 2A shows a front view and a side view of an assembly of a connecting rod and a piston. Denote point (A) as the center of a piston pin of the engine. The piston pin moves upward and downward in a straight line inside a cylinder of the engine. Denote point (B) as the center of a crank pin, which rotates around point (C) , the center of a crankshaft, whose position is unchanged. In the ideal situation of running the engine, points (A) and (B) always lie on the same plane with point (C) as the engine runs, so that the points (A) , (B) and (C) are aligned as shown in the side view in FIG. 2A. In this situation, the engine runs smoothly. The length from point (A) to point (B) is where the connecting rod is. The connecting rod does not suffer from any torque generated by the movement of the connecting rod.

In an often-encountered practical situation, however, owing to many unavoidable reasons, point (C) does not lie straightly under point (A) within a negligible deviation. FIG. 2B depicts such practical situation. Because of the misalignment, the connecting rod, which is located from point (A) to point (B) , is under tremendous torque during the time that point (B) is rotating and point (A) is moving up and down in a straight line. The pushing angle between point (A) and point (B) is always changing. The purpose of the piston pin is to connect the upper end of the connecting rod to the piston in a way such that it allows the lower end of the connecting rod to swing to the right side and the left side during the time the crankshaft is rotating, while tolerating the upper end of the connecting rod in moving back and forth to release the torque forces created when the center of the crankshaft is not in the exact correct position.

During the assembling of the engine, it is not always easy to achieve perfect alignment, especially when there are many cylinders. It is almost impossible to ensure the exact position of the center of every crankshaft to be placed exactly under the center of its relevant cylinder. It is the reason that the connecting rod is required to be made as strong as possible by hot forging in order to make it as densely made as possible. Furthermore, clearances on both ends of the piston pin are required in order to allow the upper end of the connecting rod to be able to shift in position to release torque forces due to misalignment. Such sturdy and weighty connecting rod creates a huge inertia for the engine. It is highly disadvantageous in that fuel is wasted to overcome this inertia.

Traditionally, a piston is fitted with one or more piston rings as shown in FIGS. 4A and 4B. The piston rings 801, however, only seal the cylinder internal wall but not the piston 802 itself. In practice, all piston-cylinder assemblies suffer from certain seepage around the piston rings during a combustion cycle. This seepage is one of the major causes of engine inefficiency and toxic gas exhaust. This is further described in the following.

Within a combustion cycle and during an intake stroke, as the piston moves down, the combustion chamber encompassing the space within the wall of the cylinder and the top of the piston draws in air. The air pressure inside the combustion chamber is relatively low at the beginning. The temperature of the crankshaft increases whilst working, and as a result lubricant oil in or near the crankshaft case is vaporized. Due to the lower air pressure inside the combustion chamber, the lubricant oil vapor is then sucked inside the combustion chamber, through the clearance between the piston and the piston rings, contaminating the combustion chamber.

During a compression stroke, as the piston moves back up, it compresses the air inside the combustion chamber. Since there is clearance between the piston and the piston rings, leaks take place as the chamber pressure goes up. As a result, the combustion chamber is not able to maintain the highest pressure for efficient fuel combustion.

During a power stroke, when fuel in the combustion chamber is ignited, the pressure inside the combustion chamber immediately increases by sixty to eighty times over the initial pressure. In the case of gasoline engines, the ignition starts from the spark point, which causes all fuel droplets inside the chamber to explode. In the case of diesel engine, the ignition starts from the center of the combustion chamber where the temperature is at its highest point. When the combustion chamber pressure starts to increase, at that very instance, the very fine fuel droplets around the piston crown, where the metal part is comparatively cooler than the center of ignition point, are still unburned. The instant high pressure pushes these fine droplets through the piston-piston rings clearance into the crankshaft case. Once leaving the hotspot, these fuel droplets will not be ignited. They will remain inside the crankshaft case in gas form. This escaped fuel must be diverted back to the chamber to prevent the explosion of the crankshaft case.

Finally, during an exhaust stroke, the piston moves up again and pushes the exhaust gas out of the combustion chamber through the exhaust manifold. Part of the exhaust gas, however, will escape from around the piston, permeating the crankshaft case.

As described above, with the seepage around the piston rings, the crankshaft case in operation is always filled with different gases: lubricant oil vapor, unburned fuel, and exhaust gas. These gases are being eliminated in the form of blow-by, which is to divert these gases back into the combustion chamber to be burnt along with fuel. However, the lubricant oil vapor and exhaust gas are noncombustible and are only to contaminate the pure fuel in the combustion chamber, causing less-than-optimal burning during the power stroke and creating toxic smoke.

Another problem with the piston rings is the erosion of cylinder internal wall. In order to ensure the sealing of the cylinder internal wall, the outer diameter of the piston rings is made slightly larger than that of inner diameter of the cylinders. To protect the piston from being eroded in operation, the piston rings are made of very hard alloy. The piston rings must be squeezed smaller to fit inside the cylinder. Once inside, it expands to keep tight contact with the cylinder internal wall surface and seals it. A piston moves very rapidly inside the cylinder during the combustion cycles. The hard piston rings scratch the cylinder internal wall under high speed and erode it. The piston is always expanding, when the surface of the cylinder internal wall is eroded away, the piston rings expand further to keep contact with the cylinder internal wall. But the clearance between the piston rings and the piston itself becomes wider. The seepage, thus, becomes more severe over time.

Other than the tremendous heat generated by the explosion of fuel inside the combustion chamber during a power stroke, the heat generated by the scratching between the piston rings and the cylinder wall is more challenging because it is an ongoing process. After an explosion, exhaust will be released, fresh air will be drawn in again and this will cool down the engine parts in preparation for another ignition. But the scratching on the cylinder wall is nonstop throughout the combustion cycle. The noise and immense heat generated by the cylinder internal wall scratching consume unnecessarily extra fuel. Road tests have been conducted to show that when the scratching issue is improved, a fuel saving of more than 20％can be achieved.

There is a need in the art to have better technique or mechanism for sealing the piston in cylinder to reduce seepage and cylinder internal wall scratching； and also a design in a connecting rod or an assembly comprising the connecting rod and the piston for withstanding torque forces due to the aforesaid misalignment without requiring the connecting rod to have a large inertia.

Summary of the Invention:

One aspect of the present invention provides a connecting rod configured to withstand a large torque due to misalignment among the centers of a piston pin, of a crank pin and of a crankshaft, without leading to a large inertia for the connecting rod. The connecting rod has an upper end and a lower end both arranged such that the upper end is connectable to the piston and the lower end is connectable to the crankshaft. The connecting rod can be integrated with a piston to form an assembly for converting lineal force to rotation force. An internal combustion engine is then realizable by including the connecting rod or the assembly.

The connecting rod comprises a piston pin hole located in the upper end, and an upper piston pin hole positioned above the piston pin hole. The piston pin hole has a first axis such that when a piston pin is inserted into the piston pin hole, the piston pin is oriented substantially along the first axis. The upper piston pin hole has a second axis such that when an upper piston pin is inserted into the upper piston pin hole, the upper piston pin is oriented substantially along the second axis. The first axis and the second axis are mutually substantially-orthogonal.

The connecting rod further comprises a crank pin bearing located in the lower end, and a crank pin bearing joint located in the lower end and positioned above the crank pin bearing. The crank pin bearing comprises a crank pin hole having a third axis such that when a crank pin is inserted into the crank pin hole, the crank pin is oriented substantially along the third axis. The crank pin bearing joint joins the crank pin bearing and the remaining part of the connecting rod above the crank pin bearing, and is configured such that the crank pin bearing is allowed to rotate about a fourth axis as a rotation axis. The third axis and the fourth axis are mutually substantially-orthogonal.

It is preferable that the crank pin bearing joint further comprises a bearing-joint pin receptor attached to the crank pin bearing, a bearing-joint pin hole oriented along the fourth axis, and a bearing-joint pin passing through the bearing-joint pin hole and the bearing-joint pin hole receptor such that the crank pin bearing joins the remaining part of the connecting rod above the crank pin bearing and is rotatable about the fourth axis.

It is also preferable that the connecting rod further comprises a piston pin bearing in the piston pin hole, and an extension unit having the upper piston pin hole, where the extension unit is attached to the piston pin bearing such that the extension unit is above the piston-pin bearing.

The assembly, which has the connecting rod and the piston having a piston skirt and a piston crown, further comprises a piston pin located in the piston pin hole and arranged to attach to opposite sides of the piston skirt, and an upper piston pin located in the upper pin hole and arranged to attach to the piston crown.

Another aspect of the present invention provides a coil spring seal in place of the piston rings. In one embodiment, the coil spring seal comprises three individual layers of coil rings linking up with each other to provide different functions. The piston-sealing layer is on one end of the coil spring seal, having one or more coil rings of an inner diameter slightly smaller than the outer diameter of a section of the piston where the coil spring seal is installed. The piston-sealing layer of the coil spring seal encircles the section of the piston where the coil spring seal is installed, sealing the piston permanently. The cylinder-sealing layer is on the other end of the coil spring seal, having one or more coil rings of an outer diameter slightly larger than the inner diameter of the cylinder. With the coil spring seal installed, the piston in the cylinder causes the cylinder-sealing layer of the coil spring seal to push against the cylinder internal wall from all directions, sealing cylinder internal wall at all the time. The middle part of the coil spring seal in between the piston-sealing layer and the cylinder-sealing layer is the absorption layer. The one or more coil rings making up the absorption layer have outer diameter that is smaller than the cylinder inner diameter so that they are never in contact with the cylinder internal wall； and also have inner diameter that is larger than the outer diameter of the section of the piston where the coil spring seal is installed so that they are never in contact with the piston.

The absorption layer of the coil spring seal allows big tolerance of misalignments in the piston-cylinder assembly because the coil rings in this layer are movable in the latitudinal directions, swinging around to absorb vibrations and lateral movements caused by the misalignments between the piston and the cylinder under high speed stroke motion. As such, the presence of the absorption layer of the coil spring seal also reduces the unwanted torque due to misalignment among the centers of a piston pin, of a crank pin and of a crankshaft.

The diameter difference between the coil spring seal sealing layers and the respective piston and cylinder contacting parts are small. The lateral force exerting on the sealing contact surface is mild, though continuous, thus generating negligible friction on the sealing contact surface. This in turn reduces erosion on the cylinder internal wall.

The coil spring seal, in general, has a helical structure resembling a spring. If the coil spring seal is widened laterally, the metal strap at both ends will be shortened to compensate for the change of diameter of the helical structure. Vice versa, if coil spring seal is squeezed laterally, the metal strap at both ends will elongate. This design provides high flexibility and minimizes the lateral force exerting on the sealing contact surface. With the help of lubricant oil, the coil spring seal moves smoothly along the cylinder internal wall surface. Scratching on the cylinder internal wall is reduced to a minimum.

In one embodiment, the coil spring seal is made of copper, phosphor bronze, or other alloys with high heat transfer characteristics. This helps cool down the piston by transferring the immense heat from fuel explosion in the combustion chamber to the engine body.

The multiple coil rings in each sealing layer of the coil spring seal assure perfect sealing performance. For example, on the piston surface, each coil ring of a sealing layer seals one full 360 degree around the sealing contact surface. If a leak occurs, the immediate neighboring coil ring that is sealing the sealing contact surface stops the leak. And if there is still a leak, the second neighboring coil ring that is sealing the sealing contact surface further stops the leak, and so on. This eliminates the seepage problem inherited in the use of piston ring. A fully sealed piston-cylinder assembly can completely separate the fuel from lubricant oil, thus no lubricant oil will seep into the combustion chamber to contaminate pure fuel. The fully sealed piston-cylinder assembly stops unburned fuel and exhaust from escaping into the crankshaft case, so it is not necessary to treat blow-by and there will not be smoke generated in the exhaust. The result is a cleaner engine with more efficient power output.

Other aspects of the present invention are disclosed as illustrated by the embodiments hereinafter.

Brief Description of the Drawings:

FIG. 1 depicts a conventional connecting rod connected to a piston.

FIGS. 2A and 2B depict two situations of operating an internal combustion engine where FIG. 2A is an ideal situation in which the center of a piston pin, the center of a crank pin and the center of a crankshaft are aligned and co-located on a plane, and FIG. 2B is an often-encountered practical situation in which the three aforementioned centers are not located on a single plane.

FIGS. 3A-3C depicts an assembly comprising a connecting rod and a piston according to an exemplary embodiment of the connecting rod as disclosed in the present invention, where FIGS. 3A, 3B, and 3C depict a front view, a side vide and an exploded view, respectively, of the assembly.

FIGS. 4A and 4B depict a conventional piston with a piston ring where FIG. 4A depicts the piston ring separated from the piston, and FIG. 4B depicts the piston with the piston ring installed.

FIGS. 5A and 5B depict a coil spring seal in accordance to an embodiment of the present invention where FIG. 5A depicts the general helical structure of the coil spring seal, and FIG. 5B depicts the coil spring seal with a piston-sealing layer, an absorption layer, and a cylinder-sealing layer.

FIGS. 6A and 6B depict a piston with the coil spring seal where FIG. 6A depicts the coil spring seal separated from the piston, and FIG. 6B depicts the piston with the coil spring seal installed in accordance to an embodiment of the present invention.

FIGS. 7A-7C depict the cross-sectional views of a piston with the coil spring seal where FIG. 7A depicts the piston with the coil spring seal installed in accordance to an embodiment of the present invention, FIG. 7B depicts the piston with its piston cap installed without the coil spring seal, and FIG. 7C depicts the piston with its piston cap separated from it.

Detailed Description of the Invention:

In the following description, methods and apparatuses of connecting a piston to a crankshaft and sealing a piston-cylinder assembly in a reciprocating internal combustion engine are set forth as preferred examples. It will be apparent to those skilled in the art that modifications, including additions and/or substitutions may be made without departing from the scope and spirit of the invention. Specific details may be omitted so as not to obscure the invention； however, the disclosure is written to enable one skilled in the art to practice the teachings herein without undue experimentation.

The first aspect of the present invention provides a method and apparatus of connecting a piston to a crankshaft. In an internal combustion engine, typically, a piston pin is placed under a piston crown and is attached to the opposite sides of the piston skirt. Some designs of the internal combustion engine employ the full length of the diameter of the piston head. To minimize the space inside the combustion chamber of the engine for the best fuel compression ratio, piston rings must be installed on the highest possible part of the piston neck. Thus, the piston pin is restricted at the lower part of the piston skirt, at least below the place where the piston rings are installed.

To overcome the problem of torque forces created due to misalignment of the center of crankshaft with the centers of piston pin and of crank pin without a need for a connecting rod’s body to have a large inertia, one advantageous approach is to more effectively absorb the torque forces at both ends of the connecting rod. To realize this more-effective absorption at both ends, a pair of additional joints can be designed to be installed on both ends of the connecting rod: one on the very tip of the upper end of the connecting rod, and the other one at the lower part thereof, right above a crank pin bearing cap. Consider the additional joint installed at the upper end. At the upper end, the piston pin is capable of absorbing one-dimensional linear force due to the aforementioned misalignment by shifting its position along a piston pin hole in the connecting rod. However, it is observed that the torque force created by the misalignment is rotational and is thus two-dimensional. Therefore, it is advantageous that the additional joint installed at the upper end is capable of absorbing linear force in a direction at a right angle to the direction of the one-dimensional linear force absorbed by the piston pin. The same reasoning also applies to the additional joint installed at the lower part of the connecting rod.

Refer to FIG. 1 for illustrating where to introduce the two additional joints to the conventional connecting rod 140. Inside the piston crown 115 of the piston 110, on top of the piston pin housed in the piston pin hole 148, there is a space 117 that cannot be used because of the outskirt where piston rings 116 are fitted. The piston pin can only be installed below this space 117. Right inside this space 117, immediately attaching to the lower part of the piston cap 118, an additional joint (not shown) , referred to as an upper piston pin, is placed on top of the original piston pin, being at a right angle to the piston pin. Down to the lower end of the connecting rod 140, right on top of the crank pin bearing 146, another additional joint (not shown) , referred to as a crank pin bearing joint, is placed in a parallel direction with the upper piston pin, but to the right angle with the crank pin housed in a crank pin hole 149.

By introducing the two additional joints, the connecting rod is incorporated with a certain leeway to be bent back and forth to compensate for the misplacement of the center of the crankshaft regardless of whether this center is shifted to the left or right from its original position without affecting the angle of the piston on top of the connecting rod. The connecting rod can be bent to the opposite direction off the center of the crankshaft to compensate for the misplacement. It follows that there is no need for the upper end of the connecting rod to shift back and forth along the piston pin. The hammering effect underneath the piston crown inside the piston skirt is eliminated.

While the connecting rod having the two additional joints is able to release the unbalanced torque force by bending itself when necessary, it does not exert as much torque force to the piston pin as prior designs do. The size of the piston pin can thus be reduced. Also, there is no need to spare clearances on both ends of the piston pin. The piston pin can be designed to be not in contact with the piston skirt because it is no longer required to be built to possess excessive strength for withstanding rough treatments from the connecting rod anymore.

Although there are two piston pins altogether, i.e. one conventional piston pin and one upper piston pin, the total weight of both piston pins is less than the weight of one piston pin employed in a conventional design. The reduced weight can benefit achieving reduced inertia.

The upper end of the connecting rod no longer suffers from the tremendous torque forces and the hamming forces. It follows that the thickness of a piston pin bearing on the piston pin can be reduced accordingly. Hence, the center of the piston pin can be made lower without affecting the original length of the part of connecting rod that is used to push the crank pin. The actual length of the connecting rod necessary to push the crank pin is thus shortened. In converting a lineal force to a rotation force, the conversion is most efficient if the lineal force has a direction at a right angle to the radius of the rotation circle, viz. if the angle ABC in the front view shown in FIG. 2A is 90 degrees. When the actual length of the connecting rod is shorter, its pushing angle to the crank pin is closer to the angle of achieving the highest efficiency (i.e. 90 degrees) , thereby attaining a better force efficiency. The engine using the disclosed design of the connecting rod gives a power output greater than an engine of a prior design does under the condition of same consumption in fuel.

Based on the foregoing observations and developments, the present invention is detailed as follows.

An aspect of the present invention is to provide a connecting rod configured to withstand a large torque due to misalignment among the centers of a piston pin, of a crank pin and of a crankshaft, without leading to a large inertia for the connecting rod. The connecting rod as disclosed herein can be integrated with a piston to form an assembly. FIGS. 3A, 3B and 3C depict a front view, a side view and an exploded view, respectively, of an assembly comprising a connecting rod and a piston according to an exemplary embodiment of the present invention. Herein in the specification and the appended claims, the words “above, ” “below, ” “upper, ” “lower, ” “highest, ” “lowest, ” “on top of” and other positional modifiers are interpreted according to a reference vertical direction 302 as shown in FIGS. 3A-3C.

A connecting rod 340 for connecting a piston 310 and a crankshaft has an upper end 342 and a lower end 344 both arranged such that the upper end 342 is connectable to the piston and the lower end 344 is connectable to the crankshaft. Although it is easy for an ordinary person skilled in the art to distinguish between the upper end and the lower end of the connecting rod, for the sake of clarity, it is defined herein that: an upper end of a connecting rod is the upper half of the connecting rod if the connecting rod is partitioned into two equal-length halves along the major axis of the connecting rod (i.e. the central line 303 of the connecting rod 340 as indicated in FIG. 3A) ； and a lower end of connecting rod is the lower one of the aforesaid two equal-length halves.

The connecting rod 340 comprises a piston pin hole 348 located in the upper end 342, and an upper piston pin hole 420 positioned above the piston pin hole 348. The piston pin hole 348 has a first axis 551 such that when a piston pin 630 is inserted into the piston pin hole 348, the piston pin 630 is oriented substantially along the first axis 551. The upper piston pin hole 420 has a second axis 552 such that when an upper piston pin 440 is inserted into the upper piston pin hole 420, the upper piston pin 440 is oriented substantially along the second axis 552. In particular, the first axis 551 and the second axis 552 are mutually substantially-orthogonal.

The connecting rod 340 further comprises a crank pin bearing 346 located in the lower end 344, and a crank pin bearing joint 450 located in the lower end 344 and positioned above the crank pin bearing 346. The crank pin hole 349 has a third axis 553 such that when a crank pin 640 is inserted into the crank pin hole 349, the crank pin 640 is oriented substantially along the third axis 553. The crank pin bearing joint 450 joins the crank pin bearing 346 and the remaining part of the connecting rod 340 above the crank pin bearing 346. In addition, the crank pin bearing joint 450 is configured such that the crank pin bearing 346 is allowed to rotate about a fourth axis 554 as a rotation axis. The third axis 553 and the fourth axis 554 are mutually substantially-orthogonal.

Preferably, the crank pin bearing joint 450 comprises a bearing-joint pin receptor 470 attached to the crank pin bearing 346, a bearing-joint pin hole 460 oriented along the fourth axis 554, and a bearing-joint pin 480. The bearing-joint pin 480 passes through the bearing-joint pin hole 460 and the bearing-joint pin receptor 470 such that the crank pin bearing 346 joins the remaining part of the connecting rod 340 above the crank pin bearing 346 and is rotatable about the fourth axis 554. In one implementation, the bearing-joint pin receptor 470 has one or more receptor holes 475, allowing the bearing-joint pin 480 to pass therethrough so as to join the crank pin bearing 346 and the aforesaid remaining part. In one implementation, a bearing-joint pin bearing 485 is placed inside the bearing-joint pin hole 460 to enclose the bearing-joint pin 480.

It is also preferable that the connecting rod 340 further comprises a piston pin bearing 430 in the piston pin hole 348, and an extension unit 435 having the upper piston pin hole 420. The extension unit 435 is attached to the piston pin bearing 430 such that the extension unit 435 is above the piston pin bearing 430. Thereby, the extension unit 435 is integrated into the connecting rod 340 and provides the upper piston pin hole 420. The presence of the piston pin bearing 430 in the piston pin hole 348 reduces an available space 431 for housing a piston pin 630.

An assembly used in an internal combustion engine for converting lineal force to rotation force is formable by including the connecting rod 340 as disclosed above and the piston 310 connected thereto. The piston 310 has a piston skirt 314 and a piston crown 315. The assembly further comprises a piston pin 630 and an upper piston pin 440. The piston pin 630 is located in the piston pin hole 348 and arranged to attach to opposite sides of the piston skirt 314. The upper piston pin 440 is located in the upper piston pin hole 420 and arranged to attach to the piston crown 315. In one practical implementation, each end of the upper piston pin 440 is arranged to attach to an end cap 445, which is in turn securely attached to a piston cap 318 of the piston 310 via a connecting member 510.

Although the connecting rod as disclosed in the foregoing description is constructed by introducing both the upper piston pin hole and the crank pin bearing joint to a conventional connecting rod, in one embodiment the connecting rod may be formed by having the conventional connection rod to include either the upper piston pin hole or the crank pin bearing joint but not both. Having only one of the upper piston pin hole and the crank pin bearing joint also allows withstanding a large torque due to misalignment, though this option may be less effective than having both of them together in the connecting rod.

The second aspect of the present invention provides a method and apparatus of sealing a piston-cylinder assembly using a coil spring seal. Referring to FIG. 5A. The coil spring seal, in general, has a helical structure 1001 resembling a spring. In one embodiment, this helical structure is formed by joining progressively multiple C-shaped partial rings 1002. The C-shaped partial rings 1002 can be fabricated by press-stamping or contour-cutting, such as laser cutting or wire cutting, from sheet stock. At the opening ends of each C-shaped partial ring are male and female dovetail connectors 1003 for joining another C-shaped partial ring to form a coil. The inner and outer lateral surfaces of the helical structure 1001 can further be grinded to achieve the desirable inner and outer diameters.

Referring to FIG. 5B. In one embodiment, the coil spring seal 1011 comprises three individual layers of coil rings linking up with each other to provide different functions. The piston-sealing layer 1012 is on one end of the coil spring seal 1011, having one or more coil rings of an inner diameter 1015 slightly smaller than the outer diameter of a section of the piston where the coil spring seal is installed. The piston-sealing layer 1012 of the coil spring seal encircles the section of the piston where the coil spring seal is installed, sealing the piston permanently. The cylinder-sealing layer 1014 is on the other end of the coil spring seal 1011, having one or more coil rings of an outer diameter 1018 slightly larger than the inner diameter of the cylinder.

With the coil spring seal 1011 installed, the piston in the cylinder causes the cylinder-sealing layer 1014 of the coil spring seal 1011 to push against the cylinder internal wall from all directions, sealing cylinder internal wall at all the time. The middle part of the coil spring seal in between the piston-sealing layer and the cylinder-sealing layer is the absorption layer 1013. The one or more coil rings making up the absorption layer 1013 have outer diameter 1016 that is smaller than the cylinder inner diameter so that they are never in contact with the cylinder internal wall； and also have inner diameter 1017 that is larger than the outer diameter of the section of the piston where the coil spring seal 1011 is installed so that they are never in contact with the piston.

If the coil spring seal is widened laterally, the straps at both ends will be shortened to compensate for the change of diameter of the helical structure. Vice versa, if coil spring seal is squeezed laterally, the straps at both ends will elongate. This design provides high flexibility and minimizes the lateral force exerting on the sealing contact surface. With the help of lubricant oil, the coil spring seal moves smoothly along the cylinder internal wall surface. Scratching on the cylinder internal wall is reduced to a minimum.

Referring to FIGS. 6A and 6B. In one exemplary embodiment, the coil spring seal 1021 is installed on a piston similar to that of piston rings on a piston. A typical piston comprises a piston crown which itself comprises a piston crown body 1022 and a piston cap 1023. At the one end of the piston crown body 1022 that is immediately connecting the piston cap 1023 is a trenched section 1024 with diameter smaller than that of piston crown body 1022. The coil spring seal 1021 is fitted completely in this trenched section 1024 with its piston-sealing layer coil rings tightly encircling the wall of the trenched section 1024. With the coil spring seal 1021 is fitted, the piston cap 1023 is bolted to the piston crown body 1022, securing the coil spring seal 1021 around the trenched section 1024 as shown in FIG. 6B. Other method of connecting the piston cap 1023 to the piston crown body 1022, such as a screw-on piston cap where corresponding screw threads are provided on the piston cap 1023 and the piston crown body 1022, can be used. Since the piston cap 1023 is directing exposed to the combustion chamber, usually a strong metal annoy, such as titanium is used for its composition.

Referring to FIGS. 7A-7C. In another exemplary embodiment, the piston cap 1033 is a securing ring covering only the trenched section 1034 (with coil spring seal 1031 fitted around) the of the piston crown body 1032. The piston cap 1033 is fitted around an extended plateau 1035 at the top of the piston crown body 1032. The extended plateau 1035 has a still smaller diameter than that of the trenched section 1034. To secure the piston cap 1033 around an extended plateau 1035, a screw-on method with corresponding screw threads on the inner lateral wall of the piston cap 1033 and the on the lateral wall of the extended plateau 1035 can be used. Alternative bonding methods, such as welding or bolting the piston cap 1033 to the extended plateau 1035 can also be used.

An internal combustion engine is realizable by including the connecting rod, the coil spring seal, the piston-cylinder-connecting rod assembly, or any combination thereof as disclosed above.

The foregoing description of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to the practitioner skilled in the art.

The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalence.

Claims

A connecting rod for connecting a pistonand a crankshaft, the connecting rod having an upper end and a lower end both arranged such that the upper end is connectable to the piston and the lower end is connectable to the crankshaft, the connecting rod comprising:

a piston pin hole located inthe upper end, having a first axis such that when a piston pin is inserted into the piston pin hole, the piston pin is oriented substantially along the first axis；

an upper piston pin hole positioned above the piston pin hole, having a second axis such that when an upper piston pin is inserted into the upper piston pin hole, the upper piston pin is oriented substantially along the second axis, wherein the first axis and the second axis are mutually substantially-orthogonal；

a crank pin bearing located in the lower end, comprising a crank pin hole having a third axis such that when a crank pin is inserted into the crank pin hole, the crank pin is oriented substantially along the third axis； and

a crank pin bearing joint located in the lower end and positioned above the crank pin bearing, the crank pin bearing joint joining the crank pin bearing and the remaining part of the connecting rod above the crank pin bearing, and being configured such that the crank pin bearing is allowed to rotate about a fourth axis as a rotation axis, wherein the third axis and the fourth axis are mutually substantially-orthogonal.
The connecting rod of claim 1, wherein the crank pin bearing joint comprises:

a bearing-joint pin receptor attached to the crank pin bearing；

a bearing-joint pin hole oriented along the fourth axis； and

a bearing-joint pin passing through the bearing-joint pin hole and the bearing-joint pin hole receptor such that the crank pin bearing joins the remaining part of the connecting rodabove the crank pin bearing and is rotatable about the fourth axis.
The connecting rod of claim 1, further comprising:

a piston pin bearing in the piston pin hole； and

an extension unit having the upper piston pin hole, and attached to the piston pin bearing such that the extension unit is above the piston-pin bearing.
A connecting rod for connecting a piston and a crankshaft, the connecting rod having an upper end and a lower end both arranged such that the upper end is connectable to the piston and the lower end is connectable to the crankshaft, the connecting rod comprising:

a piston pin hole located in the upper end, having a first axis such that when a piston pin is inserted into the piston pin hole, the piston pin is oriented substantially along the first axis； and

an upper piston pin hole positioned above the piston pin hole, having a second axis such that when an upper piston pin is inserted into the upper piston pin hole, the upper piston pin is oriented substantially along the second axis, wherein the first axis and the second axis are mutually substantially-orthogonal.
The connecting rod of claim 4, further comprising:

a piston pin bearing inthe piston pin hole； and

an extension unit having the upper piston pin hole, and attached to the piston pin bearing such that the extension unit is above the piston-pin bearing.
A connecting rod for connecting a piston and a crankshaft, the connecting rod having an upper end and a lower end both arranged such that the upper end is connectable to the piston and the lower end is connectable to the crankshaft, the connecting rod comprising:

a crank pin bearing located in the lower end, comprising a crank pin hole having a third axis such that when a crank pin is inserted into the crank pin hole, the crank pin is oriented substantially along the third axis； and

a crank pin bearing joint located in the lower end and positioned above the crank pin bearing, the crank pin bearing joint joining the crank pin bearing and the remaining part of the connecting rod above the crank pin bearing, and being configured such that the crank pin bearing is allowed to rotate about a fourth axis as a rotation axis, wherein the third axis and the fourth axis are mutually substantially-orthogonal.
The connecting rod of claim 6, wherein the crank pin bearing joint comprises:

a bearing-joint pin receptor attached to the crank pin bearing；

a bearing-joint pin hole oriented along the fourth axis； and

a bearing-joint pin passing through the bearing-joint pin hole and the bearing-joint pin hole receptor such that the crank pin bearing joins the remaining part of the connecting rod above the crank pin bearing and is rotatable about the fourth axis.
A piston-cylinder assembly, comprising:

a piston；

a cylinder； and

a coil spring seal for sealing both the piston and the cylinder；

wherein the coil spring seal having a plurality of coil rings each being joint progressively with another to form a helical structure；

wherein the helical structure further having four different diameter circles, with two of the diameter circles on the inside and two of the diameter circles on the outside of the helical structure； and

wherein the four different diameter circles forming a piston-sealing layer on a first end of the coil spring seal, a cylinder-sealing layer on a second end of the coil spring seal, and an absorption layer in between the piston-sealing layer and the cylinder-sealing layer.
The piston-cylinder assembly of claim 8,

wherein the piston-sealing layer having one or more coil rings of an inner diameter slightly smaller than an outer diameter of a section of the piston where the coil spring seal is installed such that the piston-sealing layer coil rings tightly encircle the section of the piston where the coil spring seal is installed and seal the piston permanently；

wherein the cylinder-sealing layer having one or more coil rings of an outer diameter slightly larger than the cylinder inner diameter such that with the coil spring seal installed, the piston in the cylinder causes the cylinder-sealing layer coil rings to push against the cylinder internal wall from all directions and seal cylinder internal wall at all time； and

wherein the absorption layer having one or more coil rings of an outer diameter that is smaller than the cylinder inner diameter so that they are never in contact with the cylinder internal wall, and of an inner diameter that is larger than the outer diameter of the section of the piston where the coil spring seal is installed so that they are never in contact with the piston.
The piston-cylinder assembly of claim 8,

wherein the piston comprises:

a piston crown body having a trenched section at the top of the piston crown body for fitting the coil spring seal within； and

a piston cap for securing the coil spring seal within the trenched section of the piston crown body.
An internal combustion engine comprising the assembly of claim 1.
An internal combustion engine comprising the assembly of claim 4.
An internal combustion engine comprising the assembly of claim 6.
An internal combustion engine comprising the assembly of claim 8.
An internal combustion engine comprising the assembly of claim 1 and the assembly of claim 8.
An internal combustion engine comprising the assembly of claim 4 and the assembly of claim 8.
An internal combustion engine comprising the assembly of claim 6 and the assembly of claim 8.