Variable compression ratio piston, bi-fuel engine and vehicle including the same.

Abstract

A variable compression ratio piston, a bi-fuel engine and a vehicle including the same are disclosed. According to this disclosure, a variable compression ratio piston is provided, which includes a piston body positioned inside a cylinder block to form the volume of a combustion chamber, and a compression ratio adjusting rotor fastened to the piston body to change the volume of the combustion chamber depending on the position.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a variable compression ratio piston, a bi-fuel engine including the same, and a vehicle.

Background Art

[0002] An internal combustion engine (hereinafter referred to as an engine) is known as a means for generating power by burning fuel inside a cylinder. In recent years, internal combustion engines are widely used in automobiles, generators, construction machines, agricultural machines, and various other industrial equipment.

[0003] Engines such as gasoline engines and diesel engines include a combustion chamber in which an air-fuel mixture burns. The combustion chamber refers to the space formed between the inner wall of the cylinder and the head of the piston. The volume, shape, etc. of the combustion chamber affect the intake and exhaust flow, the combustion speed, etc., and act as one of the factors determining the efficiency, characteristics, etc. of the engine.

[0004] One of the main design elements of the combustion chamber is the compression ratio. The compression ratio is determined by the ratio of the volume of the cylinder to the volume of the combustion chamber. The piston reciprocates between the top dead center and the bottom dead center inside the cylinder. The volume of the cylinder is defined as the volume inside the cylinder when the piston is at the bottom dead center, and the volume of the combustion chamber is defined as the volume inside the cylinder when the piston is at the top dead center. That is, the compression ratio can be expressed as the ratio of the maximum volume of the combustion chamber before compression to the minimum volume after compression during the compression stroke.

[0005] Generally, engine combustion efficiency and power output increase with increasing compression ratio. However, if the compression ratio becomes excessively high, serious damage to the engine can occur due to knocking. Knocking is a phenomenon in which the fuel-air mixture self-explodes during the compression process before it can be properly ignited by the spark plug. Knocking can cause problems such as damage to pistons and valves, and engine overheating. Therefore, engines are designed with an ideal compression ratio set according to the type of fuel used. For example, gasoline engines are typically set to a compression ratio of around 8:1 to 12:1, while diesel engines are typically set to a compression ratio of around 14:1 to 22:1.

[0006] Typical engines are designed to have a constant compression ratio. In contrast, some types of engines are configured to allow for a change in compression ratio. That is, they are configured to allow for changes in compression ratio within a range that does not cause knocking, thereby improving fuel efficiency and power output. Such types of engines are called variable compression ratio (VCR) engines. A variable compression ratio engine may be configured to change the compression ratio of the air-fuel mixture depending on the operating conditions. For example, in low-load operation, increasing the compression ratio of the air-fuel mixture can improve fuel efficiency, while in high-load operation, decreasing the compression ratio of the air-fuel mixture can prevent knocking and increase engine power.

[0007] Conventional variable compression ratio engines employ methods such as changing the height of the piston's top dead center during the compression stroke, or increasing or decreasing the volume of a sub-combustion chamber located in the cylinder head. As an example, Patent Document 1 (registered March 3, 2015) proposes a method of adjusting the compression ratio by rotating an eccentric cam located on the connecting rod. This patent document uses an eccentric cam to change the distance between the crankpin and the piston pin, thereby adjusting the compression ratio. As another example, Patent Document 2 (registered December 12, 2022) proposes a method of adjusting the compression ratio by controlling the hydraulic flow of engine oil. This patent document uses a method of increasing or decreasing the volume of the combustion chamber by moving a sliding member up and down via a hydraulic line.

[0008] The above explanation is provided to aid in understanding the technical background of this disclosure. Therefore, it should not be construed as an attempt to reduce, limit, or restrict the technical ideas of this disclosure. Furthermore, the content described or implied in the above explanation does not necessarily constitute prior art. The above explanation may include some content that does not constitute prior art. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Registered Patent Publication No. 10-1500411 [Patent Document 2] Korean Registered Patent Publication No. 10-2478081 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] Embodiments of this disclosure provide a variable compression ratio piston, a bi-fuel engine including the same, and a vehicle.

[0011] Furthermore, at least some embodiments of this disclosure provide a variable compression ratio piston capable of changing the compression ratio depending on the type of fuel, a bi-fuel engine and a vehicle including the same.

[0012] Furthermore, at least some embodiments of this disclosure provide a variable compression ratio piston that can be used in a bi-fuel engine or vehicle to improve fuel efficiency, power output, etc., and a bi-fuel engine and vehicle including the same.

[0013] Furthermore, at least some embodiments of the present disclosure provide a variable compression ratio piston that can be used in modifying a diesel engine or vehicle, a bi-fuel engine including the same, and a vehicle.

[0014] However, the technical problems that the embodiments of this disclosure seek to solve are not necessarily limited to those mentioned above. Other technical problems not mentioned will be clearly understood by a person with ordinary skill in the art to which this disclosure pertains from other descriptions in the specification, such as the detailed description. [Means for solving the problem]

[0015] According to one embodiment of the present disclosure, a variable compression ratio piston can be provided, which includes a piston body disposed inside a cylinder block to form the volume of a combustion chamber, and a compression ratio adjusting rotor fastened to the piston body and changing the volume of the combustion chamber depending on its arrangement.

[0016] According to other embodiments of the present disclosure, a bi-fuel engine can be provided, comprising a cylinder block having a combustion chamber, a variable compression ratio piston fastened to the cylinder block so as to be movable in the forward and backward directions, and a connecting rod having one end fastened to the variable compression ratio piston via a second connecting rod shaft and the other end eccentrically coupled to a crank via a first connecting rod shaft, wherein the variable compression ratio piston comprises a piston body disposed inside the cylinder block and forming the volume of the combustion chamber, and a compression ratio adjusting rotor fastened to the piston body and changing the volume of the combustion chamber with respect to fuel.

[0017] According to other aspects of this disclosure, a vehicle including the bi-fuel engine can be provided. [Effects of the Invention]

[0018] Embodiments of the present disclosure can provide a variable compression ratio piston, a bi-fuel engine including the same, and a vehicle.

[0019] Furthermore, at least some embodiments of this disclosure include a compression ratio adjusting rotor, which can change the compression ratio depending on the type of fuel. In at least some embodiments of this disclosure, the compression ratio adjusting rotor can directly change the volume of the combustion chamber, and the stroke distance of the variable compression ratio piston can be maintained despite the change in compression ratio. As a result, at least some embodiments of this disclosure can achieve a change in compression ratio depending on the type of fuel with relatively little impact on the design of existing engines. In addition, as a result, at least some embodiments of this disclosure can be implemented at a relatively low cost.

[0020] Furthermore, in at least some embodiments of the present disclosure, by appropriately varying the compression ratio according to the type of fuel, it is possible to improve fuel efficiency, output, etc. in a bi-fuel engine or vehicle. In at least some embodiments of the present disclosure, the degree of compression ratio according to the type of fuel can appropriately realize the shape deformation of the compression ratio adjusting rotating body. Thereby, at least some embodiments of the present disclosure are easily interchangeable in a bi-fuel engine using various fuels and the like.

[0021] Also, at least some embodiments of the present disclosure can be appropriately utilized to replace an existing diesel engine in vehicles, construction machinery, agricultural machinery, etc. that use an existing diesel engine.

[0022] However, the technical effects obtained by the embodiments of the present disclosure are not necessarily limited to the effects mentioned above. Other technical effects not mentioned will be clearly understood by those having ordinary knowledge in the technical field to which the present disclosure pertains from other descriptions in the specification such as detailed explanations.

Brief Description of the Drawings

[0023] [Figure 1] ​​​​​​​​​​​​​​​​​​​​​Figure 7 is a schematic longitudinal cross-sectional view of the rotating body. [Figure 9] Figure 1 shows the first operating state diagram of the bi-fuel engine. [Figure 10] Figure 1 shows the second operating state diagram of the bi-fuel engine. [Modes for carrying out the invention]

[0024] Hereinafter, embodiments of this disclosure will be described with reference to the attached drawings.

[0025] The following embodiments are provided to provide a more comprehensive and complete explanation of the technical concept of this disclosure to a person having ordinary skill in the art to which this disclosure pertains. Therefore, the technical concept of this disclosure is not necessarily limited to the following embodiments. This disclosure should be understood to encompass a wide range of equivalents, substitutes, and transformations that realize the technical concept described below.

[0026] The terms used in the following description are intended to provide a more comprehensive and complete description of specific embodiments from the perspectives described above. Therefore, the terms used in the following description should not be construed as reducing, limiting, or restricting the technical ideas of this disclosure.

[0027] In the following description, terms such as "first," "second," etc., may be used to distinguish certain components from others. However, such terms are used for clarity and should not be used to limit the technical ideas of this disclosure.

[0028] In the following descriptions, singular expressions can be interpreted as including plurals unless explicitly excluded in the context. Furthermore, in the following descriptions, the expression "includes" means that the configurations, parts, operations, features, steps, numbers, etc. described exist, and does not exclude the addition of one or more other configurations, parts, operations, features, steps, numbers, etc.

[0029] In the following description, directional terms such as “beneath,” “above,” “lower,” and “upper” are used to facilitate understanding of the components. However, such terms are provided to facilitate understanding of the disclosure in various operating and usage scenarios and should not be construed as to reduce, limit, or restrict the technical ideas of the disclosure. For example, directional terms can be determined from a relative perspective.

[0030] On the other hand, in the following drawings, the depiction of each component may be exaggerated or omitted for the sake of clarity and ease of explanation.

[0031] Figure 1 is a schematic diagram showing a bi-fuel engine according to one embodiment of the present disclosure.

[0032] In some embodiments, the bi-fuel engine 100 may be configured to use multiple types of fuel. For example, the bi-fuel engine 100 may be configured to use different fuels, including gasoline and compressed natural gas (CNG). In other examples, the bi-fuel engine 100 may be configured to use different fuels, including gasoline and liquefied natural gas (LNG). The bi-fuel engine 100 may be configured to use different combinations of different fuels, other than those exemplified above.

[0033] For the sake of explanation, below, one type of fuel supplied to the bi-fuel engine 100 will be referred to as the "first fuel," and the other type of fuel as the "second fuel." For example, the first fuel may include compressed natural gas, and the second fuel may include gasoline.

[0034] In some embodiments, the first and second fuels may have different ideal compression ratios. Here, the ideal compression ratio refers to a fuel compression ratio that is accepted in the industry, taking into account combustion efficiency, engine knocking, and other factors. For example, gasoline engines typically have a compression ratio of about 8:1 to 12:1, and compressed natural gas engines typically have a compression ratio of about 10:1 to 13:0. Here, compressed natural gas has a relatively high octane number and burns stably without knocking even at high compression ratios compared to gasoline.

[0035] In some embodiments, the bi-fuel engine 100 may include gasoline as one of the different fuels. This allows the bi-fuel engine 100 to be realized with the basic structure of a gasoline engine.

[0036] In some embodiments, the bi-fuel engine 100 can be realized in various engines that generate power by burning fuel inside a cylinder. For example, the bi-fuel engine 100 can be realized in vehicle engines and can be used in generators, construction machinery, agricultural machinery, and various other industrial equipment.

[0037] In some embodiments, the bi-fuel engine 100 can be applied to replace existing diesel engines in vehicles, construction machinery, agricultural machinery, etc. In such cases, the existing diesel engine can be replaced by removing part or all of the existing diesel engine installed in the vehicle, etc., in an appropriate manner and newly installing the bi-fuel engine 100 according to the embodiments of this disclosure in the vehicle, etc.

[0038] In some embodiments, the bi-fuel engine 100 can be applied by modifying an existing gasoline engine in vehicles, construction machinery, agricultural machinery, etc. In such cases, the bi-fuel engine 100 can replace the existing gasoline engine by sharing some components with the existing gasoline engine and replacing or modifying some other components. Herein, the bi-fuel engine 100 according to embodiments of the present disclosure can easily modify an existing engine at a relatively low cost by reducing the replacement or modification of existing components.

[0039] Referring to Figure 1, in some embodiments, the bi-fuel engine 100 may include a cylinder block 110. The cylinder block 110 can form a combustion chamber 111 into which a mixture of fuel and air is supplied and burned. The combustion chamber 111 may be located inside the cylinder block 110. In some embodiments, multiple sets of cylinder blocks 110 may be provided. For example, there may be two, three, four, six, eight, and so on. Since each cylinder block 110 can be identical or similarly constructed, for convenience, this description will focus on one cylinder block 110.

[0040] In some embodiments, the bi-fuel engine 100 may include a cylinder head 120. The cylinder head 120 may be coupled to the cylinder block 110 to form part of the combustion chamber 111. In some cases, the cylinder head 120 may be partially or entirely formed integrally with the cylinder block 110. In the illustrated embodiment, the cylinder head 120 is located on top of the cylinder block 110.

[0041] In some embodiments, the cylinder head 120 may include an intake port 121 communicating with the combustion chamber 111. The intake port 121 may be controlled to open and close by an intake valve 121a and configured to supply a fuel-air mixture to the combustion chamber 111. In some embodiments, the cylinder head 120 may also include an exhaust port 122 communicating with the combustion chamber 111. The exhaust port 122 may be controlled to open and close by an exhaust valve 122a and configured to exhaust the combustion gases burned in the combustion chamber 111. In some embodiments, a spark plug 123 may be positioned between the intake port 121 and the exhaust port 122 to provide a spark to the combustion chamber 111.

[0042] In some embodiments, the bi-fuel engine 100 may include a variable compression ratio piston 130. The variable compression ratio piston 130 may be formed to be movable forward and backward within the cylinder block 110. The variable compression ratio piston 130 can move forward (up) toward the combustion chamber 111 to compress the air-fuel mixture, and can move backward (down) due to the combustion (explosion) of the air-fuel mixture in the combustion chamber 111 to supply rotational power to the crankshaft 140. The detailed configuration of the variable compression ratio piston 130 will be described later.

[0043] In some embodiments, the bi-fuel engine 100 may include a crankcase 141. The crankcase 141 may extend from the lower part of the cylinder block 110. Optionally, the crankcase 141 may be partially or entirely formed integrally with the cylinder block 110.

[0044] In some embodiments, a crank 140 may be located inside the crankcase 141. The crank 140 may include a crankshaft S1 and be rotatably supported in the crankcase 141 about the crankshaft S1.

[0045] In some embodiments, a connecting rod 150 may be located inside the crankcase 141. One end (lower end) of the connecting rod 150 may be fastened to the crank 140 so as to be rotatable around a first connecting rod shaft S2. The first connecting rod shaft S2 may be eccentrically positioned with respect to the crank shaft S1. The other end (upper end) of the connecting rod 150 may be fastened to a variable compression ratio piston 130 so as to be rotatable around a second connecting rod shaft S3. The connecting rod 150 may be configured to move the variable compression ratio piston 130 back and forth (up and down) via the first and second connecting rod shafts S2 and S3.

[0046] Figure 2 is a schematic perspective view showing an enlarged view of the variable compression ratio piston and connecting rod shown in Figure 1. Figure 3 is a perspective view of the variable compression ratio piston and connecting rod shown in Figure 2 from a different direction. Figure 4 is a schematic longitudinal cross-sectional view of the variable compression ratio piston and connecting rod shown in Figure 2.

[0047] Referring to Figures 2 to 4, in some embodiments, the variable compression ratio piston 130 may include a piston body 131 and a compression ratio adjusting rotating body 132.

[0048] The piston body 131 can form the overall outer shape of the variable compression ratio piston 130. In some embodiments, the planar shape of the piston body 131 may be formed to be substantially circular, and the outer side surface 131e of the piston body 131 may be formed to be substantially cylindrical. The piston body 131 is fastened to the connecting rod 150 so as to be rotatable around the second connecting rod axis S3, and can move up and down within the cylinder block 110 by the operation of the connecting rod 150.

[0049] The compression ratio adjusting rotor 132 may be positioned approximately in the center of the piston body 131 in a plan view. The compression ratio adjusting rotor 132 may be positioned so that at least a portion of it is exposed to the piston head portion 131a of the piston body 131. In the illustrated embodiment, the compression ratio adjusting rotor 132 is positioned so as to be exposed to the central region of the outer upper surface of the piston body 131. The compression ratio adjusting rotor 132 is exposed to the outer upper surface of the piston body 131 and can form part of the piston head portion 131a. That is, at least a portion of the compression ratio adjusting rotor 132 is exposed to the piston head portion 131a and can contribute to the formation of the bottom surface region of the combustion chamber 111.

[0050] In some embodiments, the compression ratio adjusting rotor 132 may be formed to be rotatable over a predetermined range around the first connecting rod axis S2. The position of such a compression ratio adjusting rotor 132 changes depending on its rotational position around the first connecting rod axis S2. For example, the compression ratio adjusting rotor 132 rotates by a predetermined angle around the first connecting rod axis S2 in an arrangement as shown in the illustrated embodiment, and its position changes. In some embodiments, the rotation or change in the position of the compression ratio adjusting rotor 132 can function to change the volume of the combustion chamber 111.

[0051] On the other hand, in some embodiments, the connecting rod 150 may be provided with an actuation part 160. The actuation part 160 may be configured to change the position of the compression ratio adjustment rotor 132. In some embodiments, the actuation part 160 may include a first actuation part 161 and a second actuation part 162. The first actuation part 161 can function to rotate the compression ratio adjustment rotor 132 to a first position, and the second actuation part 162 can function to rotate the compression ratio adjustment rotor 132 to a second position. In some embodiments, the first and second actuation parts 161, 162 can be implemented in a configuration that is housed on one side of the connecting rod 150. In the illustrated embodiment, the first and second actuation parts 161, 162 are located on the left and right sides of the connecting rod 150.

[0052] Specifically, the first operating unit 161 may include a first conversion rod 161a. The first conversion rod 161a may be a bar shape extending in the longitudinal direction. One end (upper end) of the first conversion rod 161a may be fastened to the compression ratio adjusting rotor 132 via a first upper end link 161b. The first upper end link 161b provides a lateral pivot axis, and the first conversion rod 161a may be formed to rotate around the first upper end link 161b. The other end (lower end) of the first conversion rod 161a may be fastened to the first movable cap 161d via a first lower end link 161c. The first lower end link 161c provides a lateral pivot axis, and the first conversion rod 161a may be formed to rotate around the first lower end link 161c.

[0053] The first movable cap 161d may be located on the first conversion cylinder 161e. The first conversion cylinder 161e may include a first movable chamber (not indicated) (see second movable chamber 162g), and the first movable cap 161d may be located to house within the first movable chamber. The first movable chamber may extend in the operating direction of the first movable cap 161d so that the first movable cap 161d can move a predetermined operating distance. In the illustrated embodiment, the first movable chamber extends so as to be inclined at a predetermined angle with respect to the vertical direction.

[0054] The first movable chamber may be connected to the first movable channel 161f. The first movable channel 161f can supply or discharge working fluid to the first movable chamber. As a result, the first movable cap 161d, positioned in the first movable chamber, can move up and down within the first movable chamber. In some embodiments, the first movable channel 161f may extend into the connecting rod 150. Although not shown, a hydraulic line or the like, to which working fluid is supplied or discharged, may also be connected to the end of the first movable channel 161f.

[0055] The second actuation unit 162 may be formed substantially similarly to the first actuation unit 161. The second actuation unit 162 may include a second conversion rod 162a, one end (upper end) of which may be fastened to the compression ratio adjusting rotor 132 via a second upper end link 162b. The other end (lower end) of the second conversion rod 162a may be fastened to the second movable cap 162d via a second lower end link 162c. The second movable cap 162d may be located on the second conversion cylinder 162e, which may include a second movable chamber 162g. The second movable cap 162d may be positioned to be housed in the second movable chamber 162g. The second movable chamber 162g is connected to a second movable passage 162f, which can supply or discharge working fluid to or from the second movable chamber 162g.

[0056] In some embodiments, the first and second actuation parts 161 and 162 may be positioned at different locations along the longitudinal direction of the connecting rod 150. For example, the first actuation part 161 may be positioned at a relatively lower location along the longitudinal direction of the connecting rod 150, and the second actuation part 162 may be positioned at a relatively higher location along the longitudinal direction of the connecting rod 150. In some embodiments, the first and second actuation parts 161 and 162 may also be able to operate in an inclined direction at a predetermined angle with respect to the vertical direction. Such positions and operating directions of the first and second actuation parts 161 and 162 can contribute to the effective transmission of operating force to the compression ratio adjusting rotor 132. Furthermore, despite the addition of the first and second actuation parts 161 and 162, the connecting rod 150 can maintain a compact structure and shape.

[0057] Figure 5 is an enlarged view of the variable compression ratio piston shown in Figure 4. Figure 6 shows the variable compression ratio piston shown in Figure 5 with the rotating body removed. Figure 7 shows the rotating body separated from Figure 5. Figure 8 is a schematic longitudinal cross-sectional view of the rotating body shown in Figure 7.

[0058] Referring to Figures 5 to 8, in some embodiments, the piston body 131 may include a piston head portion 131a. The piston head portion 131a may be formed as the upper surface region of the piston body 131. In some embodiments, the piston head portion 131a may be formed in a shape in which the upper surface of the piston body 131 is recessed and retracted to a predetermined extent.

[0059] In some embodiments, a head opening 131b may be formed in the center of the upper surface of the piston body 131. The head opening 131b may be formed through the center of the upper surface of the piston body 131. In some embodiments, the head opening 131b may be formed in a circular shape in plan view. A circular head opening 131b has the advantage of facilitating the shape design and sealing of the compression ratio adjusting rotor 132 in relation to the compression ratio adjusting rotor 132.

[0060] In some embodiments, the head opening 131b has a radius R2 that is a predetermined ratio to the overall radius R1 of the piston body 131. For example, the head opening 131b may have a radius R2 that is 30% to 70% of the overall radius R1 of the piston body 131. If the radius R2 of the head opening 131b is too small, such as 30% or less as exemplified, the range of volume change by the compression ratio adjusting rotor 132 will be too small. Conversely, if the radius R2 of the head opening 131b is too large, such as 70% or more as exemplified, it will be disadvantageous for proper placement of the compression ratio adjusting rotor 132 and ensuring the rigidity of the piston body 131.

[0061] On the other hand, in some embodiments, the piston body 131 may include a piston skirt 131c. The piston skirt 131c extends downward from the piston head portion 131a and can form the side of the piston body 131. The piston skirt 131c may include an inner side surface 131d positioned toward the compression ratio adjusting rotor 132 and an outer side surface 131e corresponding to the inner side surface 131d. The outer side surface 131e of the piston skirt 131c can form a substantially cylindrical outer surface. The inner side surface 131d of the piston skirt 131c may be formed such that a portion of its upper end contacts the outer surface of the compression ratio adjusting rotor 132. The contact area between the inner side surface 131d of the piston skirt 131c and the outer surface of the compression ratio adjusting rotor 132 can form a closed shape in plan view. For example, the contact area can form a substantially annular shape in plan view. The contact area that forms a closed figure can function as a sealing area that seals the space between the head opening 131b and the compression ratio adjusting rotating body 132.

[0062] In some embodiments, a second seal groove 131f may be formed in the contact area. The second seal groove 131f may be located adjacent to the upper end of the inner side surface 131d of the piston body 131. The second seal groove 131f may also extend to have a closed shape in plan view. For example, the second seal groove 131f may extend to have an annular shape in plan view. A sealing member is fastened to the second seal groove 131f, and the sealing member can function to seal the space between the head opening 131b and the compression ratio adjusting rotor 132.

[0063] In some embodiments, the inner side surface 131d of the piston body 131 may be provided with a rotating body guide surface 131g. The rotating body guide surface 131g may be formed as a portion of the upper end of the inner side surface 131d adjacent to the head opening 131b. The rotating body guide surface 131g may be formed as a partially spherical surface having a predetermined curvature. In some embodiments, the curvature of the rotating body guide surface 131g may be formed to correspond to the first operating surface 132b of the compression ratio adjustment rotating body 132. That is, the rotating body guide surface 131g may be formed to have a curvature corresponding to the first operating surface 132b. Such a rotating body guide surface 131g can ensure an appropriate contact area with the compression ratio adjustment rotating body 132 and contribute to improved sealing performance. Furthermore, such a rotating body guide surface 131g can function to guide the proper rotational movement of the compression ratio adjustment rotating body 132.

[0064] In some embodiments, a first seal groove 131i may be provided on the outer surface 131e of the piston body 131. The first seal groove 131i may extend circumferentially along the outer surface 131e of the piston body 131. A sealing member is fastened to the first seal groove 131i, and the sealing member can function to seal the space between the piston body 131 and the cylinder block 110.

[0065] In some embodiments, the piston body 131 may include a piston pin 131h. The piston pin 131h can provide a first connecting rod shaft S2. The piston pin 131h may extend laterally between both inner sides 131d of the piston skirt 131c.

[0066] On the other hand, in some embodiments, the compression ratio adjusting rotor 132 may be fastened to the piston body 131 so as to be rotatable by a predetermined angle. The compression ratio adjusting rotor 132 may be provided with a pin fastening hole 132a that penetrates the compression ratio adjusting rotor 132 laterally, and the pin fastening hole 132a may be fastened to a piston pin 131h provided in the piston body 131. As a result, the compression ratio adjusting rotor 132 becomes rotatable by a predetermined angle around the piston pin 131h or the second connecting rod axis S3.

[0067] In some embodiments, the compression ratio adjusting rotor 132 may have a first upper link 161b fastened to one side (lower left end) and a second upper link 162b fastened to the other side (upper right end). The compression ratio adjusting rotor 132 can receive operating force from the first and second operating parts 161 and 162 via the first and second upper links 161b and 162b.

[0068] In some embodiments, the compression ratio adjusting rotor 132 may include a first operating surface 132b. In the illustrated embodiment, the first operating surface 132b is exemplified as the upper surface region of the compression ratio adjusting rotor 132. The first operating surface 132b can be selectively coupled to the head opening 131b depending on the arrangement of the compression ratio adjusting rotor 132. That is, the first operating surface 132b can be coupled to the head opening 131b or detached from the head opening 131b depending on the arrangement of the compression ratio adjusting rotor 132.

[0069] In some embodiments, the first working surface 132b may have a curved shape that is bulging and protruding. The protruding first working surface 132b is contrasted with the second working surface 132c, which will be described later. The protruding first working surface 132b can function to reduce the volume of the combustion chamber 111 by a corresponding volume. That is, the first working surface 132b is positioned so that at least a portion of it protrudes into the combustion chamber 111 through the head opening 131b, and can function to relatively reduce the volume of the combustion chamber 111.

[0070] In some embodiments, the first operating surface 132b may be formed as a partially spherical surface having a predetermined curvature. Furthermore, the curvature of the first operating surface 132b may be formed to correspond to the rotating body guide surface 131g of the piston body 131. That is, the first operating surface 132b may be formed to have a curvature corresponding to the rotating body guide surface 131g. As described above, such a first operating surface 132b has functions such as improving sealing performance and guiding rotational movement.

[0071] In some embodiments, the first operating surface 132b may be formed in a substantially circular shape in plan view, and the circular first operating surface 132b may have a predetermined radius R3 in plan view. The radius R3 of the first operating surface 132b may be a predetermined amount smaller than the radius R1 of the entire piston body 131 and a predetermined amount larger than the radius R2 of the head opening 131b. For example, the radius R3 of the first operating surface 132b may be 5% to 10% larger than the radius R2 of the head opening 131b. This ensures that an appropriate sealing area is secured between the first operating surface 132b and the head opening 131b.

[0072] On the other hand, in some embodiments, the compression ratio adjusting rotor 132 may be provided with a second operating surface 132c. In the illustrated embodiment, the second operating surface 132c is exemplified as a side region of the compression ratio adjusting rotor 132. Similar to the first operating surface 132b described above, the second operating surface 132c can be selectively coupled to the head opening 131b depending on the arrangement of the compression ratio adjusting rotor 132. That is, the second operating surface 132c can be coupled to the head opening 131b or detached from the head opening 131b depending on the arrangement of the compression ratio adjusting rotor 132. Note that in Figure 5 and other figures, the state in which the first operating surface 132b is coupled to the head opening 131b and the second operating surface 132c is detached from the head opening 131b is shown.

[0073] In some embodiments, the second operating surface 132c may have a less curved shape than the first operating surface 132b. Alternatively, the second operating surface 132c may be formed to be closer to a planar shape than the first operating surface 132b. In the illustrated embodiment, the second operating surface 132c has a shape that is substantially close to a planar shape. The second operating surface 132c can function to increase the volume of the combustion chamber 111 by a predetermined amount compared to the first operating surface 132b. That is, the second operating surface 132c is formed to protrude less into the combustion chamber 111 than the first operating surface 132b, and can function to relatively increase the volume of the combustion chamber 111.

[0074] In some embodiments, the second operating surface 132c may be formed in a substantially circular shape when viewed from above. That is, in the illustrated embodiment, the shape of the second operating surface 132c when viewed from the side may be formed in a substantially circular shape. Furthermore, the circular second operating surface 132c may have a predetermined radius R4.

[0075] The radius R4 of the second operating surface 132c may be a predetermined amount smaller than the overall radius R1 of the piston body 131, and a predetermined amount larger than the radius R2 of the head opening 131b. For example, the radius R4 of the second operating surface 132c may be 5% to 10% larger than the radius R2 of the head opening 131b. This is similar in principle to the first operating surface 132b described above.

[0076] Figure 9 is a diagram showing the first operating state of the bi-fuel engine shown in Figure 1.

[0077] Referring to Figure 9, in some operating examples, the bi-fuel engine 100 is driven by a first fuel. For example, the first fuel may include compressed natural gas. When the first fuel is supplied, the compression ratio adjusting rotor 132 is positioned such that the first operating surface 132b is fastened to the head opening 131b. The operating unit 160 can be positioned such that the first conversion rod 161a is at bottom dead center and the second conversion rod 162a is at top dead center, and the compression ratio adjusting rotor 132 is positioned as described above.

[0078] The compression ratio adjusting rotor 132 is positioned such that its first working surface 132b is exposed to the combustion chamber 111, thereby determining the volume of the combustion chamber 111. That is, the volume of the combustion chamber 111 is formed by the shape of the first working surface 132b. The shape of the first working surface 132b is appropriately designed considering the ideal compression ratio of the first fuel. For example, the outer shape, area, and protrusion of the first working surface 132b are designed considering the ideal compression ratio of compressed natural gas. As a result, the bi-fuel engine 100 can proceed through the engine cycle with a combustion chamber 111 volume optimized for the first fuel.

[0079] Figure 10 is a diagram showing the second operating state of the bi-fuel engine shown in Figure 1.

[0080] Referring to Figure 10, in some operating examples, the bi-fuel engine 100 is driven by a second fuel. The second fuel may be a different fuel from the first fuel; for example, the second fuel may contain gasoline. When the second fuel is supplied, the compression ratio adjusting rotor 132 is positioned such that the second operating surface 132c is fastened to the head opening 131b. The operating unit 160 can be positioned with the first conversion rod 161a at top dead center and the first conversion rod 161a at bottom dead center, and the compression ratio adjusting rotor 132 can be positioned as described above.

[0081] Similar to the case of the first working surface 132b described above, the compression ratio adjusting rotor 132 is positioned such that the second working surface 132c is exposed to the combustion chamber 111, thereby determining the volume of the combustion chamber 111. That is, the volume of the combustion chamber 111 is formed by the shape of the second working surface 132c. The shape of the second working surface 132c is appropriately designed considering the ideal compression ratio of the second fuel. For example, the outer shape, area, and protrusion of the second working surface 132c are designed considering the ideal compression ratio of gasoline. As a result, the bi-fuel engine 100 can proceed through the engine cycle with a combustion chamber 111 volume optimized for the second fuel.

[0082] As described above, embodiments of the present disclosure can provide a variable compression ratio piston, a bi-fuel engine including the same, and a vehicle.

[0083] Furthermore, at least some embodiments of this disclosure include a compression ratio adjusting rotor, which can change the compression ratio depending on the type of fuel. In at least some embodiments of this disclosure, the compression ratio adjusting rotor can directly change the volume of the combustion chamber, and the stroke distance of the variable compression ratio piston can be maintained despite the change in compression ratio. As a result, at least some embodiments of this disclosure can achieve a change in compression ratio depending on the type of fuel with relatively little impact on the design of existing engines. In addition, as a result, at least some embodiments of this disclosure can be implemented at a relatively low cost.

[0084] Furthermore, at least some embodiments of this disclosure can improve fuel efficiency and output in a bi-fuel engine or vehicle by appropriately changing the compression ratio depending on the type of fuel. In at least some embodiments of this disclosure, the degree of compression ratio change depending on the type of fuel can be appropriately achieved by deforming the shape of the compression ratio adjusting rotor. As a result, at least some embodiments of this disclosure are easily interchangeable in bi-fuel engines using various fuels.

[0085] Furthermore, at least some embodiments of this disclosure can be appropriately utilized to replace existing diesel engines in vehicles, construction machinery, agricultural machinery, and other applications that use existing diesel engines.

[0086] While embodiments of this disclosure have been described above, any person with ordinary skill in the art may modify or change this disclosure in various ways, such as by adding, changing, deleting, or adding components, without departing from the technical idea of ​​this disclosure as described in the claims, and such modifications or changes are also included within the scope of the rights of this disclosure. [Explanation of Symbols]

[0087] 100 Bi-fuel engine 110 Cylinder Block 120 Cylinder Head 130 Variable Compression Ratio Piston 140 Crank 150 Connecting Rods 160 Operating part

Claims

1. The piston body is positioned inside the cylinder block and forms the volume of the combustion chamber, The piston body is fastened to the piston body and includes a compression ratio adjusting rotating body that changes the volume of the combustion chamber depending on its arrangement, Variable compression ratio piston.

2. The variable compression ratio piston according to claim 1, wherein the piston body has a head opening formed through the upper surface region that forms the volume of the combustion chamber.

3. The variable compression ratio piston according to claim 2, wherein the head opening is formed in a circular shape having a predetermined radius in a plan view.

4. The variable compression ratio piston according to claim 3, wherein the radius of the head opening is by a predetermined amount smaller than the radius of the first operating surface of the compression ratio adjusting rotating body, or the radius of the second operating surface of the compression ratio adjusting rotating body.

5. The piston body includes a piston skirt that forms the side of the piston body. The piston skirt is The outer surface, which is positioned toward the inner surface of the cylinder block, Including an inner surface corresponding to the outer surface, The inner surface includes a contact area that contacts the outer surface of the compression ratio adjusting rotating body. A variable compression ratio piston according to claim 1.

6. The variable compression ratio piston according to claim 5, wherein the contact area is formed in the shape of a closed figure including a ring in a plan view.

7. The variable compression ratio piston according to claim 5, wherein the inner surface is provided with a second seal groove located at the upper end of the contact area and formed in the shape of a closed figure including a ring in a plan view.

8. The inner surface is provided with a rotating body guide surface in a portion of the upper end region including the contact region. The variable compression ratio piston according to claim 5, wherein the rotating body guide surface is formed of a partially spherical surface having a predetermined curvature.

9. The variable compression ratio piston according to claim 8, wherein the rotating body guide surface is formed to have a curvature corresponding to a part of the outer surface of the compression ratio adjusting rotating body.

10. The aforementioned compression ratio adjusting rotating body is A first operating surface is coupled to the head opening of the piston body and forms a predetermined volume of the combustion chamber, The first operating surface is selectively coupled to the head opening and includes a second operating surface that forms a predetermined volume of the combustion chamber, A variable compression ratio piston according to claim 1.

11. The variable compression ratio piston according to claim 10, wherein the volume of the combustion chamber formed by the first operating surface is different from the volume of the combustion chamber formed by the second operating surface.

12. The first working surface is formed as a partially spherical surface that protrudes with a predetermined curvature, The second operating surface is formed in a less curved shape or a planar shape than the first operating surface. A variable compression ratio piston according to claim 10.

13. The variable compression ratio piston according to claim 12, wherein the curvature of the first operating surface is formed to correspond to a part of the inner surface of the piston body.

14. A cylinder block equipped with a combustion chamber, A variable compression ratio piston is fastened to the cylinder block so as to be movable in the forward and backward directions, A connecting rod is included, one end of which is fastened to the variable compression ratio piston via a second connecting rod shaft, and the other end of which is eccentrically connected to the crank via a first connecting rod shaft. The aforementioned variable compression ratio piston is A piston body is disposed inside the cylinder block and forms the volume of the combustion chamber, The piston body is fastened to the piston body and includes a compression ratio adjusting rotating body that changes the volume of the combustion chamber with respect to the fuel, Bi-fuel engine.

15. The bi-fuel engine according to claim 14, further comprising a movable part for changing the arrangement of the compression ratio adjusting rotating body.

16. The aforementioned movable part is A first operating part is fastened to one side of the compression ratio adjusting rotating body and rotates the compression ratio adjusting rotating body in one direction, A second operating part is fastened to the other side of the compression ratio adjusting rotating body and rotates the compression ratio adjusting rotating body in the opposite direction to the one direction, The bi-fuel engine according to claim 15.

17. The first operating unit is, A first conversion rod, one end of which is rotatably fastened to the compression ratio adjusting rotating body via a first upper end link, and the other end of which is rotatably fastened to the first movable cap via a first lower end link, The first conversion cylinder forms a first movable chamber from which the first movable cap moves up and down, The first movable channel includes a first movable channel for supplying or discharging working fluid to the first movable chamber, The bi-fuel engine according to claim 16.

18. The bi-fuel engine according to claim 16, wherein the first actuation unit and the second actuation unit are arranged on the connecting rod, are positioned at different locations in the longitudinal direction of the connecting rod, and are formed to operate in an inclined direction at a predetermined angle with respect to the vertical direction.

19. A vehicle comprising the bi-fuel engine described in claim 14.

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