Transmission system capable of adaptive transmitting and method of driving the same

Abstract

In a transmission system capable of speed-adaptive shifting and a method of driving the same, the transmission system includes a friction shifting unit interposed between a driving unit and a driving transmission unit, which rotates by means of frictional force with the driving unit. The friction shifting unit includes a plurality of variable units, each having a variable length, and as the rotational speed of the driving unit varies, the lengths of the variable units vary, thereby varying the radius of the friction shifting unit.

Description

Technology Field

[0001] The present invention relates to a transmission system capable of speed-adaptive shifting and a driving method thereof, and more specifically, to a transmission system capable of speed-adaptive shifting and a driving method thereof in which shifting is performed without power and shifting is performed such that the gear ratio varies according to the variation of the applied speed, thereby enabling effective response to various driving conditions and being implemented with a lightweight design. Background Technology

[0002] Generally, the buckling effect refers to a phenomenon in which deformation, such as bending, occurs in a slender, long cylindrical structure due to an applied compressive load even under a load below the proportional limit of the material.

[0003] Recently, technologies for processing information using mechanical computing methods that utilize this buckling phenomenon are being developed.

[0004] For example, through U.S. Registered Patent No. 10655452, a technology for evaluating the condition of pipe structures using the aforementioned buckling phenomenon is being developed, and through U.S. Published Patent No. 2023-0157178, a technology regarding a structural displacement self-generating sensor based on the post-buckling effect is also being developed.

[0005] As described above, while the development of mechanical structures utilizing this buckling phenomenon is still in its early stages, its applications are highly diverse. However, concepts such as the aforementioned buckling phenomenon have not yet been applied to technological fields like transmissions; consequently, the development of transmission systems utilizing non-powered buckling is becoming increasingly important, particularly in vehicles like electric cars, to reduce battery consumption. Prior art literature

[0006] U.S. Registered Patent No. 10655452 U.S. Published Patent No. 2023-0157178 The problem to be solved

[0007] Accordingly, the technical problem of the present invention is conceived from this point, and the objective of the present invention is to provide a speed-adaptive shifting system capable of shifting without power, and shifting so that the gear ratio varies according to the variation of the applied speed, thereby enabling effective response to various driving conditions and being implemented with a lightweight design.

[0008] In addition, another objective of the present invention is to provide a driving method for the transmission system. means of solving the problem

[0009] A transmission system according to one embodiment for realizing the above-described objective of the present invention includes a friction transmission unit interposed between a driving unit and a driving transmission unit, which rotates by means of frictional force with said driving unit. The friction transmission unit includes a plurality of variable units, each having a variable length, and as the rotational speed of said driving unit varies, the lengths of said variable units vary, thereby varying the radius of said friction transmission unit.

[0010] In one embodiment, as the rotational speed of the drive unit decreases, the length of the variable units increases, and the radius of the friction transmission unit may increase.

[0011] In one embodiment, as the rotational speed of the drive unit increases, the length of the variable units decreases, and the radius of the friction transmission unit may decrease.

[0012] In one embodiment, the friction transmission unit may further include a rotating body that rotates according to the rotation of the driving unit, and a plurality of friction units that contact the driving unit and the driving transmission unit.

[0013] In one embodiment, the variable units are connected between the rotating body and the friction unit and can be spaced apart from each other at a constant distance.

[0014] In one embodiment, each of the variable units may include a fixed rod fixed to the rotating body, a variable rod connected to the friction unit, and a variable body connected between the fixed rod and the variable rod.

[0015] In one embodiment, the variable body is varied to switch between a first position and a second position, and in the first position, the variable rod is positioned so as to be close to the rotating body side, thereby reducing the length of the variable unit, and in the second position, the variable rod is positioned so as to be far from the rotating body, thereby increasing the length of the variable unit.

[0016] In one embodiment, the variable body may be extended in a diagonal direction following a first direction between the fixed rod and the variable rod that are extended parallel to each other, or in a diagonal direction following a second direction opposite to the first direction.

[0017] In one embodiment, each of the variable units may further include an elastic member interposed between the rotating body and the variable rod to provide elastic force toward the variable rod.

[0018] In one embodiment, the friction transmission unit may further include a fixed frame fixed at a preset position, and a linear rod unit extending a predetermined length from the fixed frame and connected to the rotating body.

[0019] In one embodiment, the linear rod has a predetermined elastic force, so that when the length of the variable units increases as the rotational speed of the driving unit decreases, an external force greater than the elastic force of the linear rod can be applied so that the radius of the friction transmission unit can increase.

[0020] In one embodiment, as the difference between the elastic force of the linear load part and the elastic force of the elastic part increases, the magnitude of the external force that must be applied to increase the radius of the friction shift part may increase.

[0021] In one embodiment, each of the friction units includes an upper surface portion in contact with the driving unit and the driving transmission unit, and a lower surface portion connected to the variable unit, and the thickness of each of the friction units can be gradually increased.

[0022] In one embodiment, as the radius of the friction shifter increases, the upper surfaces of the friction units extend to each other to form a circular outer surface, and as the radius of the friction shifter decreases, the lower surface of the friction unit may be located outside the upper surface of the adjacent friction unit.

[0023] In a driving method of a transmission system according to an embodiment for realizing the above-described objective of the present invention, when the rotational speed of the driving unit decreases by a command of the control unit, the shear torque increases due to the friction difference between the driving unit and the driving transmission unit, and the radius of the frictional transmission unit increases, thereby decreasing the rotational speed of the driving transmission unit. Additionally, when the rotational speed of the driving unit increases by a command of the control unit, the centripetal force of the frictional transmission unit increases, and the radius of the frictional transmission unit decreases, thereby increasing the rotational speed of the driving transmission unit. Effects of the invention

[0024] According to embodiments of the present invention, a friction shifter is provided in which the radius is varied by the difference in frictional force between a driving unit and a driving transmission unit, and as the radius of the friction shifter is varied, shifting is performed automatically, and in particular, since no separate power is consumed during the process of shifting, a power-free shifting system can be implemented.

[0025] Accordingly, through the above-mentioned power-free transmission system, it can be applied to vehicles requiring reduced battery consumption, such as electric vehicles, thereby enabling flexible gear shifting according to driving conditions while maintaining high battery efficiency.

[0026] In particular, the above-mentioned shifting is implemented when the rotational speed of the drive unit is varied. As the rotational speed of the drive unit decreases or increases, the radius of the friction shifting unit increases or decreases to vary the gear ratio and enable shifting, thereby allowing for speed-adaptive shifting.

[0027] At this time, the change in radius of the friction transmission unit is implemented through the variation of the lengths of the variable units provided inside, and since each of the variable units includes a variable body that switches between a first position and a second position and changes the position through a so-called buckling effect, the radius of the friction transmission unit can be accurately varied in a speed-adaptive manner.

[0028] Meanwhile, each of the above variable units includes an elastic part, thereby easily implementing a change in posture in which the radius of the friction shifting part increases relatively, and thereby improving the ease of shifting.

[0029] In addition, the friction shifting unit includes a linear rod having a predetermined elastic force. By controlling the magnitude of the elastic force of the linear rod, the degree of torque inducing the shifting can be varied, thereby allowing for the diverse setting of the range in which shifting is possible. Thus, the torque range in which shifting is performed is set considering various driving environments, and a shifting system can be applied to enable shifting optimized for the driving environment. Brief explanation of the drawing

[0030] FIG. 1 is a block diagram illustrating a transmission system according to one embodiment of the present invention. Figure 2 is a schematic diagram illustrating the transmission system of Figure 1. Figure 3 is a schematic diagram showing an enlarged view of the friction unit and variable unit of Figure 2. FIG. 4a is a schematic diagram illustrating the first position of the friction transmission unit of FIG. 1, and FIG. 4b is a schematic diagram specifically illustrating the variable unit, which is part A of FIG. 4a. FIG. 5a is a schematic diagram illustrating the second position of the friction transmission unit of FIG. 1, and FIG. 5b is a schematic diagram specifically illustrating the variable unit, which is part B of FIG. 5a. FIGS. 6a and FIGS. 6b are schematic diagrams illustrating the state of a variable unit in a first position and a second position, respectively, in a transmission system according to another embodiment of the present invention. Figure 7 is a flowchart illustrating the driving method of the transmission system of Figure 1. Specific details for implementing the invention

[0031] The present invention is susceptible to various modifications and may take various forms, and embodiments are to be described in detail in the text. However, this is not intended to limit the invention to the specific disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals have been used for similar components in the description of each figure. Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms.

[0032] The above terms are used solely for the purpose of distinguishing one component from another. The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0033] In this application, terms such as "comprising" or "consisting of" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0034] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0035] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings.

[0036] FIG. 1 is a block diagram illustrating a transmission system according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the transmission system of FIG. 1. FIG. 3 is an enlarged schematic diagram illustrating the friction unit and variable unit of FIG. 2.

[0037] Referring to FIGS. 1 and 2, the transmission system (10) according to the present embodiment includes a control unit (100), a driving unit (200), a friction transmission unit (300), a driving transmission unit (400), and a wheel unit (500).

[0038] The above control unit (100) controls the operation of the above drive unit (200), and it is sufficient to provide the drive unit (200) with control commands, for example, to increase, decrease, or stop the rotational driving speed of the above drive unit (200).

[0039] The above driving unit (200) is driven by a control command of the above control unit (100), and may be, for example, a rotary motor. Accordingly, the above driving unit (200) rotates by rotary driving and can rotate at a predetermined speed (V1) with respect to a central axis, as shown in FIG. 2.

[0040] The friction transmission unit (300) contacts the driving unit (200) and rotates by receiving rotational driving force from the rotation of the driving unit (200), so that rotational driving force is ultimately transmitted through the frictional force between the outer surface of the driving unit (200) and the outer surface of the friction transmission unit (300).

[0041] That is, when the driving unit (200) rotates clockwise at a predetermined speed (V1) as in FIG. 2, the friction transmission unit (300) rotates counterclockwise at a predetermined speed (U1), which is opposite to the rotation direction of the driving unit (200).

[0042] Meanwhile, the drive transmission unit (400) contacts the other outer surface of the friction transmission unit (300) and receives rotational driving force from the rotation of the friction transmission unit (300) and rotates at a predetermined speed (W1), so that rotational driving force is ultimately transmitted through the frictional force between the outer surface of the friction transmission unit (400) and the outer surface of the drive transmission unit (400).

[0043] At this time, although the drive transmission unit (400) is not illustrated in detail, it is connected to the wheel unit (500), and thereby the wheel unit (500) can ultimately rotate to induce movement of the vehicle. In this case, the specific connection relationship between the drive transmission unit (400) and the wheel unit (500) can be varied in various ways, and a structure in which power is transmitted to the wheel unit through a conventional drive transmission unit can be applied.

[0044] In the present embodiment, the transmission system (10) implements the transmission of rotational driving force between the driving unit (200) and the driving transmission unit (400) through the friction transmission unit (300). As described later, the friction transmission unit (300) performs the transmission of rotational driving force along with the transmission of the transmission, thereby also performing the role of a so-called transmission.

[0045] Below, the friction transmission unit (300) is described in more detail.

[0046] Referring to FIGS. 2 and 3, the friction transmission unit (300) specifically includes a fixed frame (310), a linear load unit (320), a rotating body (330), a friction unit (340), and a variable unit (350).

[0047] Although the above fixed frame (310) is not illustrated, it is a frame structure that is fixed at a fixed position in a space where the above transmission system (10) is provided. For example, if the above transmission system (10) is applied to an electric vehicle, the above fixed frame (310) can be fixed at a predetermined position inside the frame structure of the electric vehicle.

[0048] Alternatively, the fixed frame (310) may not be configured as a separate frame structure as illustrated, but may correspond to the frame structure of the electric vehicle itself.

[0049] The linear rod portion (320) may be a rod having a predetermined length extending in one direction from the fixed frame (310), and as described below, the linear rod portion (320) may be an elastic body having a predetermined elastic force. Accordingly, the linear rod portion (320) may be compressed when an external force is applied along the direction in which the linear rod portion (320) extends, and may return to its original length when the applied external force is removed.

[0050] That is, the linear rod portion (320) may be a linear rod of an elastic body that repeatedly performs compression and restoration depending on the application or dissipation of an external force. In this case, the linear rod portion (320) is connected to the center of the rotating body (330), so that the external force applied to the linear rod portion (320) is ultimately the rotating body (330).

[0051] That is, when a predetermined external force is applied to the linear rod (320) through the center of the rotating body (330), the linear rod (320) may be compressed along the extended length direction according to the application of the external force, and when the applied external force is extinguished, the linear rod (320) may be extended and restored to its original length.

[0052] The above-mentioned rotating body (330) corresponds to a predetermined rotating block located at the center of rotation when the friction transmission unit (300) rotates, and has a rigid body structure, so that when the friction transmission unit (300) rotates, the rotating body (330) rotates with respect to the center of the rotating body (330).

[0053] In this case, the rotating body (330) may have a circular plate shape having a predetermined radius as illustrated, and the radius of the rotating body (330) may be designed to vary.

[0054] The friction unit (340) is spaced apart from the rotating body (330) by a predetermined distance to form a surface that contacts the outer surface of the friction transmission unit (300), that is, the driving unit (200) and the driving transmission unit (400). Accordingly, the friction unit (340) may be formed to have an overall circular band or circular ring shape.

[0055] That is, as the driving unit (200) rotates, the driving unit (200) and the friction unit (340) rub against each other, and rotational driving force is transmitted by friction, and similarly, as the friction unit (340) rotates, rotational driving force is transmitted to the driving transmission unit (400) which rubs against the friction unit (340).

[0056] The variable units (350) are interposed in multiple numbers between the friction unit (340) and the rotating body (330), and the variable units (350) can be arranged at regular intervals from each other. That is, as illustrated, the variable units (350) are provided in multiple numbers in a circumferential direction between the outer surface of the rotating body (330) and the inner surface of the friction unit (340), and can be arranged at equal intervals along the circumferential direction.

[0057] More specifically, as illustrated in FIG. 3, the variable unit (350) includes a fixed rod (360), a variable rod (370), and a variable body (380).

[0058] Thus, the fixed rod (360) is fixed on the outer surface of the rotating body (330), and the variable rod (370) is fixed on the lower surface (341), which is the inner surface of the friction unit (340). At this time, although specific details will be described later, the lengths of the fixed rod (360) and the variable rod (370) are not varied, but the relative position of the variable rod (370) is varied by the variable body (380), so that the overall length of the variable unit (350) is varied.

[0059] In addition, as the length of the variable unit (350) is varied, the overall radius of the friction transmission unit (300) decreases or increases, thereby enabling a change in rotational power transmitted from the driving unit (200) to the driving transmission unit (400). A detailed description of this change implementation will be provided later.

[0060] Meanwhile, as shown in FIG. 3, the friction unit (340) has a shape in which the thickness increases overall, including an upper surface (342) and a lower surface (341).

[0061] That is, the friction unit (340) forms the outer surface of the friction transmission unit (300) on the outside of the rotating body (330) as shown in FIG. 2, and forms the entire outer surface in a structure in which a plurality of friction units (340) are connected to each other adjacently. In addition, each friction unit (340) has a shape that has a predetermined length and gradually increases in thickness as shown in FIG. 3. Thus, each friction unit (340) with a spiral shape that gradually increases in thickness is arranged adjacently to each other to form the outer surface of the friction transmission unit (300).

[0062] Additionally, as previously explained, the variable rod (370) is fixed to the lower portion (341) of the friction unit (340), and the outer surface of the driving unit (200) and the outer surface of the driving transmission unit (400) are in contact on the upper portion (342).

[0063] In the following, the shifting state according to the shape variation of the friction shifting unit (300) is specifically explained based on the change in length of the variable unit (350) and the change in the contact state of the friction unit (340) accordingly.

[0064] Meanwhile, for the convenience of explanation, the illustration of the above-mentioned drive transmission unit (400) has been omitted.

[0065] FIG. 4a is a schematic diagram illustrating the first position of the friction transmission unit of FIG. 1, and FIG. 4b is a schematic diagram specifically illustrating the variable unit, which is part A of FIG. 4a.

[0066] First, referring to FIGS. 4a and 4b, when the friction shift unit (300) is in the first position, the length of the variable unit (350) is kept relatively short, and accordingly, the radius of the circular shape formed by the friction unit (340) is also formed relatively small.

[0067] Additionally, in the case of the first position mentioned above, the drive unit (200) rotates at a first speed (V1), which is a relatively fast rotational speed, and this first speed (V1) of the drive unit (200) is transmitted to the drive transmission unit (400) through the rotation (U1) of the friction transmission unit (300).

[0068] That is, in the first position, the friction transmission unit (300) has a relatively high gear ratio, and according to this high gear ratio, power is transmitted so that rotational driving at a high speed with a relatively low torque is possible.

[0069] In this way, in the first position, the variable unit (350) is formed to have a relatively short length, and the specific connection relationship of the variable unit (350) can be confirmed through FIG. 4b.

[0070] That is, the variable unit (350) comprises a fixed rod (360), a variable rod (370), and a variable body (380), as previously described, wherein the fixed rod (360) corresponds to a rod that is fixed on the rotating body (330) and extends to have a predetermined length.

[0071] At this time, through FIG. 4b, the fixed rod (360) is illustrated as being formed by including a pair of first and second fixed rods (361, 362) spaced apart from each other, but is not limited thereto, and may have a shape of a circular cylinder or a polygonal cylinder with a hollow interior, fixed on the rotating body (330), and extended to have a predetermined length.

[0072] As described above, with the fixed rod (360) fixed on the rotating body (330) with a constant length, the variable rod (370) is varied in position along the center of the fixed rod (360).

[0073] In addition, the position variation of the variable rod (370) is implemented in a direction from the rotating body (330) toward the friction unit (340), and thus the extension direction of the variable rod (370) is parallel to the extension direction of the fixed rod (360).

[0074] That is, the variable rod (370) has a variable position relative to the fixed rod (360), and this relative position variation is implemented through the variable body (380).

[0075] At this time, the variable body (380) extends between the fixed rod (360) and the variable rod (370). As shown in FIG. 4b, the fixed rod (360) is configured to include a pair of first and second fixed rods (361, 362), so the variable body (380) is also configured to include a first variable body (381) connected between the first fixed rod (361) and the variable rod (370), and a second variable body (382) connected between the second fixed rod (362) and the variable rod (370).

[0076] Accordingly, the number of the variable body (380) can also vary depending on the structure or number of the fixed rod (360), provided that the operation of the variable body (380) must be the same even if multiple units are provided.

[0077] The variable body (380) fixes the relative position of the variable rod (370) to the fixed rod (360) so that the variable rod (370) is close to the rotating body (330) in the so-called first position as in FIG. 4b. Thus, the overall length of the variable unit (350) is formed to be relatively short.

[0078] In addition, as the length of the variable unit (350) is formed to be relatively short, the distance between the friction unit (340) and the outer surface of the rotating body (330) is also formed to be relatively short, and accordingly, the radius of the friction transmission unit (300), which is the distance from the center of the rotating body (330) to the outer surface of the friction unit (340), is also formed to be small overall.

[0079] At this time, the first variable body (381) and the second variable body (382) are connected and extended diagonally between the variable rod (370) and the first and second fixed rods (361, 362) as illustrated. In particular, the extended diagonal direction may be a so-called lower diagonal direction (first direction) that extends from the fixed rod (360) toward the variable rod (370) and toward the rotating body (330).

[0080] Additionally, each of the first and second variable bodies (381, 382) extends along the lower diagonal direction, and accordingly, the relative position of the variable rod (370) to the fixed rod (360) can be maintained stably to a certain extent by the variable body (380) extending in the first direction.

[0081] The above variable body (380) is such that its posture is varied between the first posture and the second posture in FIG. 5b described later, thereby inducing a switching type of bending or switching type of posture variation, such as the so-called buckling effect.

[0082] That is, the variable body (380) and the variable rod (370) connected thereto are variable so as to be switched only between the first position in FIG. 4b and the second position in FIG. 5b, and do not maintain a fixed position in any other position other than the first and second positions.

[0083] In addition, the relative position variation of the variable body (380) and the variable rod (370) is induced by a predetermined external force, and the switching variation to the first position and the second position is realized only when an external force of a predetermined level or higher is applied.

[0084] As described above, in the first position as illustrated in FIGS. 4a and 4b, the variable rod (370) is positioned close to the rotating body (330) through a connection with the variable body (380), and its position is varied by a predetermined length (d) compared to FIG. 5b. Accordingly, the variable unit (350) also has its length shortened by the predetermined length (d), and consequently, the radius of the friction transmission part (300) is also reduced by the predetermined length (d).

[0085] In addition, through the friction transmission unit (300) having such a relatively reduced radius, the rotational speed of the drive unit (200) is transmitted to the drive transmission unit (400) through a relatively high gear ratio.

[0086] FIG. 5a is a schematic diagram illustrating the second position of the friction transmission unit of FIG. 1, and FIG. 5b is a schematic diagram specifically illustrating the variable unit, which is part B of FIG. 5a.

[0087] Referring to FIGS. 5a and 5b, when the friction shift unit (300) is in a second position, the length of the variable unit (350) is maintained relatively long, and accordingly, the radius of the circular shape formed by the friction unit (340) is also formed relatively long.

[0088] Additionally, in the case of the second position mentioned above, the drive unit (200) rotates at a second speed (V2), which is a relatively slow rotational speed, and this second speed (V2) of the drive unit (200) is transmitted to the drive transmission unit (400) through the rotation (U2) of the friction transmission unit (300).

[0089] That is, in the second position, the friction transmission unit (300) has a relatively low gear ratio, and transmits power so that rotational driving at a low speed with a relatively high torque is possible according to this low gear ratio.

[0090] In this way, in the second position, the variable unit (350) is formed to have a relatively long, that is, increased length, and the specific connection relationship of the variable unit (350) can be confirmed through FIG. 5b.

[0091] The variable body (380) fixes the relative position of the variable rod (370) to the fixed rod (360) so that in the so-called second position, as in FIG. 5b, the variable rod (370) moves away from the rotating body (330). Thus, the overall length of the variable unit (350) is formed to be relatively long.

[0092] In addition, as the length of the variable unit (350) is formed to be relatively long, the distance between the friction unit (340) and the outer surface of the rotating body (330) is also formed to be relatively long, and accordingly, the radius of the friction transmission unit (300), which is the distance from the center of the rotating body (330) to the outer surface of the friction unit (340), is formed to be large overall. Accordingly, the friction transmission unit (300) has an unfolded shape as shown in FIG. 5a.

[0093] At this time, the first variable body (381) and the second variable body (382) are connected and extended diagonally between the variable rod (370) and the first and second fixed rods (361, 362) as illustrated. In particular, the extended diagonal direction may be a so-called upper diagonal direction (second direction) that extends from the fixed rod (360) toward the variable rod (370) and toward the friction unit (340).

[0094] In this case, the second direction, which is the upper diagonal direction, is defined as a direction opposite to the first direction, which is the lower diagonal direction, as explained with reference to FIG. 4b above.

[0095] Additionally, each of the first and second variable bodies (381, 382) extends along the upper diagonal direction, and accordingly, the relative position of the variable rod (370) to the fixed rod (360) can be maintained stably to a certain extent by the variable body (380) extending in the second direction.

[0096] The attitude variation of the above variable body (380) corresponds to a switching type of bending or a switching type of attitude variation, such as the so-called buckling effect as described above.

[0097] In addition, as previously explained, the variable body (380) and the variable rod (370) connected thereto are variable so as to switch only between the first position in FIG. 4b and the second position in FIG. 5b, and do not maintain a fixed position in any other position other than the first and second positions. Furthermore, the relative position variation of the variable body (380) and the variable rod (370) is induced by a predetermined external force, and the switching variation to the first and second positions is realized only when an external force of a predetermined level or higher is applied.

[0098] As described above, in the second position as illustrated in FIGS. 5a and 5b, the variable rod (370) is positioned away from the rotating body (330) through a connection with the variable body (380). Accordingly, the length of the variable unit (350) also increases by the predetermined length (d), and consequently, the radius of the friction transmission part (300) also increases by the predetermined length (d).

[0099] In addition, through the friction transmission unit (300) having such a relatively increased radius, the rotational speed of the drive unit (200) is transmitted to the drive transmission unit (400) through a relatively low gear ratio.

[0100] The induction of a first posture as in FIGS. 4a and 4b, and a second posture as in FIGS. 5a and 5b, will be described later with reference to FIG. 7.

[0101] Meanwhile, as previously explained, each of the friction units (340) is formed in a spiral shape with increasing width or thickness, and a plurality of them are arranged adjacent to each other to form the outer surface of the friction transmission unit (300).

[0102] In addition, in the first position of FIG. 4a, the radius of the friction transmission part (300) formed by the friction unit (340) is relatively small, and in the second position of FIG. 5a, the radius of the friction transmission part (300) formed by the friction unit (340) is relatively large.

[0103] That is, in FIG. 4a, each of the friction units (340) is arranged to be closer together to minimize the radius of the friction transmission unit (300) formed by the friction units (340) overall, and in FIG. 5a, each of the friction units (340) is arranged to be further apart to maximize the radius of the friction transmission unit (300) formed by the friction units (340) overall.

[0104] Specifically, in the first position of FIG. 4a, the lower surface (341) of the friction unit (340) is positioned on the upper surface (342) of an adjacent friction unit, and accordingly, the friction units (340) adjacent to each other are arranged so that a portion overlaps and form a cylindrical shape.

[0105] In particular, as the friction units overlap each other and form an overall cylindrical shape, the upper surface (342) of the friction unit (340) is arranged in a shape that partially protrudes outward. Thus, the frictional force between the outer surface of the driving unit (200) and the upper surface (342) of the friction unit (340) is further increased. Therefore, due to this increase in relative frictional force, an increase in external force caused by shear torque is induced when the driving unit (200) changes from a high-speed driving state to a low-speed driving state, and thereby, the change from the first position to the second position of the variable unit (350) can be induced more easily. Such position change will be described later.

[0106] In contrast, in the second position of FIG. 5a, the friction unit (340) is arranged so that both ends are connected to each other without any overlapping portion with adjacent friction units. That is, the two ends of the friction unit (340) are arranged so that they are connected to the two ends of adjacent friction units, so that the upper surface (342) of the friction unit (340) is continuously connected to form a cylindrical shape overall.

[0107] That is, in this second position, since the two ends of the friction unit (340) are connected to each other and arranged continuously, the friction transmission unit (300) forms a relatively large radius.

[0108] As described above, when varying to the first and second postures explained earlier, a change in posture is induced in which the friction units are arranged to overlap with adjacent friction units or their ends are connected to each other, and accordingly, the radius of the outer surface formed by the friction units as a whole is varied.

[0109] However, such variation is merely a switching variation between the first position and the second position, and is not a change to any position between the first position and the second position. As previously explained, such switching variation is induced by a switching variation such as the so-called buckling phenomenon of the variable body (380).

[0110] FIGS. 6a and FIGS. 6b are schematic diagrams illustrating the state of a variable unit in a first position and a second position, respectively, in a transmission system according to another embodiment of the present invention.

[0111] In the transmission system according to the present embodiment, except that an elastic part (371) is interposed between the variable rod (370) and the rotating body (330), it is substantially the same as the transmission system (10) described with reference to FIGS. 1 to 5b, so the same reference numbers are used for the same components and redundant descriptions are omitted.

[0112] That is, as shown in FIG. 6a and FIG. 6b, in the transmission system according to the present embodiment, the elastic part (371) is interposed between the outer surface of the rotating body (330) and the variable rod (370).

[0113] In this way, as the elastic part (371) is interposed, the external force required to change from the first position of FIG. 6a to the second position of FIG. 6a is relatively reduced, but the external force required to change from the second position of FIG. 6b to the first position of FIG. 6a is relatively increased.

[0114] That is, the external force for compressing the elastic part (371) to bring the variable rod (370) closer to the rotating body (330) by means of the elastic force of the elastic part (371) must be increased compared to the embodiment described with reference to FIGS. 4a and 5a, but the external force for expanding the elastic part (371) to bring the variable rod (370) closer to the friction unit (340) may be reduced compared to the embodiment described with reference to FIGS. 4a and 5a.

[0115] Through this, when the drive unit (200) rotates at a relatively high speed with the radius of the friction transmission unit (300) in the first position being relatively small, the drive unit (200) rotates at a relatively low speed with the radius of the friction transmission unit (300) in the second position being relatively large, the length of the variable unit (350) can be extended relatively easily with the assistance of the elastic unit (371).

[0116] In contrast, when the drive unit (200) rotates at a relatively low speed with the radius of the friction transmission unit (300) in the second position being relatively large, the drive unit (200) rotates at a relatively high speed with the radius of the friction transmission unit (300) in the first position being relatively small, a higher external force may be required to compress and reduce the length of the variable unit (350) by the elastic force of the elastic unit (371).

[0117] Ultimately, by varying the elastic force of the elastic part (371), the magnitude of the torque required when changing between the first position and the second position can be varied, which means that the torque range in which the gear shift is performed can be varied and set.

[0118] Below, the driving method of the transmission system (10) of FIG. 1 is described, and in particular, the variation of the posture between the first posture and the second posture is also described in detail.

[0119] Figure 7 is a flowchart illustrating the driving method of the transmission system of Figure 1.

[0120] Referring to FIG. 7, first, the driving unit (200) is driven by a driving command of the control unit (100), and the driving unit (200), which was rotating at a preset driving speed, can have its rotational speed varied by a driving command of the control unit (100).

[0121] For example, the case in which the rotational speed of the drive unit (200) is reduced through the drive command of the control unit (100) (steps S10 and S20) is described as follows.

[0122] That is, when the above driving unit (200) is driven at a relatively fast rotational speed, the friction transmission unit (300) is maintained in the first position described with reference to FIG. 4a and FIG. 4b.

[0123] Accordingly, when the rotational speed of the drive unit (200) is reduced through the drive command of the control unit (100) (step S20), the drive unit (200) rotating at high speed rotates at low speed, but the drive transmission unit (400) is still maintained at high speed.

[0124] Thus, due to the difference in rotational speed between the drive unit (200) and the drive transmission unit (400), the friction transmission unit (300), particularly the friction unit (340), increases the shear torque due to the difference in friction induced by the difference in rotational speed (step S30).

[0125] Due to this increase in shear torque, the connection state of the variable body (380) in the variable unit (350) connected to the friction unit (340) is switched, and accordingly, the variable rod (370) is positioned to be away from the rotating body (330).

[0126] Thus, the overall length of the variable unit (350) increases, and the radius of the outer surface formed by the friction unit (340) increases, thereby changing to a second position as in FIGS. 5a and 5b (step S40).

[0127] At this time, as previously explained, since the linear rod portion (320) is a linear rod having a predetermined elastic force, in order for the radius of the friction unit (340) to increase due to the external force provided to the variable rod (370) as a result of the increase in the shear torque, an external force greater than the preset elastic force of the linear rod portion (320) must be applied. Thus, the linear rod portion (320) is compressed, and the radius of the friction unit (340) can increase.

[0128] That is, by pre-setting the magnitude of the elastic force of the linear load portion (320), the degree of shear torque that causes variation from the first position to the second position can be controlled.

[0129] In addition, as shown in FIG. 6a and FIG. 6b, if the elastic member (371) is interposed, when changing from the first position of FIG. 6a to the second position of FIG. 6b, relatively easy expansion, that is, an increase in the radius of the friction unit (340), can be induced by the elastic force of the elastic member (371).

[0130] Accordingly, by varying the magnitude of the elastic force of the linear load portion (320) and the magnitude of the elastic force of the elastic portion (371), the magnitude of the external force, i.e., the torque that induces the variation of the posture, when varying from the first posture to the second posture can be varied.

[0131] For example, if the elastic force of the linear load portion (320) is set to be greater than the elastic force of the elastic portion (371), the magnitude of the external force, i.e., the torque, required for variation from the first position to the second position is relatively larger. That is, a relatively high rotational torque must be applied so that the friction transmission portion (300) can be varied from the first position to the second position.

[0132] Thus, in order for the change, i.e., shifting from the first position to the second position, to be performed through the friction shift unit (300), the rotational speed of the drive unit (200) must be reduced relatively more, and thereby high torque must be provided.

[0133] As described above, by varying the difference between the elastic force of the linear load section (320) and the elastic force of the elastic section (371), the torque range in which the friction transmission section (300) can be shifted can be varied, and thereby the shifting point can be set considering the operating environment or operating conditions of a vehicle such as an electric vehicle.

[0134] Meanwhile, as described above, as the rotational speed of the drive unit (200) decreases, the radius of the friction transmission unit (300) increases, and as the gear ratio decreases, the rotational speed of the drive transmission unit (400) also decreases (step S50).

[0135] In contrast, the case where the rotational speed of the drive unit (200) increases through the drive command of the control unit (100) (steps S10 and S60) is described as follows.

[0136] That is, when the above driving unit (200) is driven at a relatively slow rotational speed, the friction transmission unit (300) is maintained in the second position described with reference to FIGS. 5a and FIGS. 5b.

[0137] Accordingly, when the rotational speed of the drive unit (200) increases through the drive command of the control unit (100) (step S60), the drive unit (200) rotating at a low speed rotates at a high speed, but the drive transmission unit (400) is still maintained in a low-speed rotational state.

[0138] Thus, due to the difference between the rotational speed of the drive unit (200) and the rotational speed of the drive transmission unit (400), the shear torque in the friction transmission unit (300), particularly the friction unit (340), is reduced due to the difference in friction induced by the difference in rotational speed (step S70). In addition, as the rotational speed of the drive unit (200) increases, the centripetal force applied to the friction transmission unit (300) increases (step S70).

[0139] Due to the reduction of the shear torque and the increase in centripetal force, the connection state of the variable body (380) in the variable unit (350) connected to the friction unit (340) is switched, and accordingly, the variable rod (370) is positioned to be close to the rotating body (330).

[0140] Thus, the overall length of the variable unit (350) is reduced, and the radius of the outer surface formed by the friction unit (340) is reduced, so that it is varied to a first position as in FIGS. 4a and 4b (step S80).

[0141] At this time, as previously explained, the elastic force of the linear load portion (320) induces a reduction in the radius of the outer surface formed by the friction unit (340), thereby inducing a relatively easy variation when changing to the first position, so that the shifting of the friction shift portion (300) is easily implemented.

[0142] However, as shown in FIG. 6a and FIG. 6b, if the elastic member (371) is interposed to have a predetermined elastic force, the variation to the first position may be relatively limited by the elastic force of the elastic member (371). That is, since the elastic member (371) must be compressed, an external force required for the compression of the elastic member (371) must be applied.

[0143] Accordingly, through the design of the elastic force of the linear load part (320) and the elastic part (371), the variation to the first position can be implemented relatively easily or relatively difficultly, and this can be implemented relatively differently from the ease of variation to the second position.

[0144] Accordingly, if the elastic force of the linear load part (320) is designed to be greater than the elastic force of the elastic part (371), the change to the first posture is induced relatively easily and the change to the second posture is induced relatively difficultly, and if designed in the opposite way, the required state of the external force during such posture change is set in the opposite way.

[0145] Thus, the range in which shifting is performed through the friction shifting unit (300) can be set in various ways, as previously explained.

[0146] Meanwhile, as described above, as the rotational speed of the drive unit (200) increases, the radius of the friction transmission unit (300) decreases, and as the gear ratio increases, the rotational speed of the drive transmission unit (400) also increases (step S90).

[0147] As described above, when the rotational speed of the drive unit (200) is switched from a relatively high speed (V1) to a relatively low speed (V2) according to the drive command of the control unit (100), the radius of the friction transmission unit (300) is varied to correspond to this, and the transmission is performed, and finally, the rotational driving force is provided to the wheel unit (500) through the drive transmission unit (400).

[0148] According to the embodiments of the present invention as described above, a friction shift unit is provided in which the radius is varied by the difference in frictional force between the driving unit and the driving transmission unit, and as the radius of the friction shift unit is varied, shifting is performed automatically, and in particular, since no separate power is consumed during the process of shifting, a power-free shifting system can be implemented.

[0149] Accordingly, through the above-mentioned power-free transmission system, it can be applied to vehicles requiring reduced battery consumption, such as electric vehicles, thereby enabling flexible gear shifting according to driving conditions while maintaining high battery efficiency.

[0150] In particular, the above-mentioned shifting is implemented when the rotational speed of the drive unit is varied. As the rotational speed of the drive unit decreases or increases, the radius of the friction shifting unit increases or decreases to vary the gear ratio and enable shifting, thereby allowing for speed-adaptive shifting.

[0151] At this time, the change in radius of the friction transmission unit is implemented through the variation of the lengths of the variable units provided inside, and since each of the variable units includes a variable body that switches between a first position and a second position and changes the position through a so-called buckling effect, the radius of the friction transmission unit can be accurately varied in a speed-adaptive manner.

[0152] Meanwhile, each of the above variable units includes an elastic part, thereby easily implementing a change in posture in which the radius of the friction shifting part increases relatively, and thereby improving the ease of shifting.

[0153] In addition, the friction shifting unit includes a linear rod having a predetermined elastic force. By controlling the magnitude of the elastic force of the linear rod, the degree of torque inducing the shifting can be varied, thereby allowing for the diverse setting of the range in which shifting is possible. Thus, the torque range in which shifting is performed is set considering various driving environments, and a shifting system can be applied to enable shifting optimized for the driving environment.

[0154] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as set forth in the following claims. Explanation of the symbols

[0155] 10 : Transmission system 100 : Control unit 200: Drive unit 300: Friction transmission unit 310: Fixed frame 320: Linear load section 330 : Rotating body 340 : Friction unit 350 : Variable unit 360 : Fixed load 370 : Variable load 380 : Variable body 371 : Elastic part 400 : Drive transmission part 500 : Wheel part

Claims

Claim 1 A transmission system comprising a friction transmission unit interposed between a driving unit and a driving transmission unit and rotating by means of frictional force with said driving unit, wherein the friction transmission unit comprises a plurality of variable units, each having a variable length; a rotating body that rotates according to the rotation of said driving unit; and a plurality of friction units in contact with said driving unit and said driving transmission unit, wherein the radius of said friction transmission unit is varied by varying the lengths of said variable units as the rotational speed of said driving unit varies. Claim 2 A transmission system according to claim 1, characterized in that as the rotational speed of the drive unit decreases, the length of the variable units increases, and the radius of the friction transmission unit increases. Claim 3 A transmission system according to claim 1, characterized in that as the rotational speed of the drive unit increases, the length of the variable units decreases, thereby reducing the radius of the friction transmission unit. Claim 4 delete Claim 5 A transmission system according to claim 1, wherein the variable units are connected between the rotating body and the friction unit and are spaced apart from each other at a constant distance. Claim 6 A transmission system according to claim 5, wherein each of the variable units comprises: a fixed rod fixed to the rotating body; a variable rod connected to the friction unit; and a variable body connected between the fixed rod and the variable rod. Claim 7 A transmission system according to claim 6, wherein the variable body is variable so as to switch between a first position and a second position, wherein in the first position the variable rod is positioned so as to be close to the rotating body side, thereby reducing the length of the variable unit, and in the second position the variable rod is positioned so as to be far from the rotating body, thereby increasing the length of the variable unit. Claim 8 A transmission system according to claim 7, wherein the variable body is extended in a diagonal direction following a first direction or in a diagonal direction following a second direction opposite to the first direction between the fixed rod and the variable rod that are extended parallel to each other. Claim 9 A transmission system according to claim 6, wherein each of the variable units further comprises an elastic member interposed between the rotating body and the variable rod to provide elastic force toward the variable rod. Claim 10 A transmission system according to claim 9, wherein the friction transmission unit further comprises a fixed frame fixed at a preset position; and a linear rod unit extending a predetermined length from the fixed frame and connected to the rotating body. Claim 11 A transmission system according to claim 10, wherein the linear rod portion has a predetermined elastic force, and when the length of the variable units increases as the rotational speed of the drive portion decreases, the radius of the friction transmission portion increases only when an external force greater than the elastic force of the linear rod portion is applied. Claim 12 A transmission system according to claim 11, characterized in that as the difference between the elastic force of the linear load part and the elastic force of the elastic part increases, the magnitude of the external force that must be applied to increase the radius of the friction transmission part increases. Claim 13 A transmission system according to claim 1, wherein each of the friction units comprises an upper surface portion in contact with the driving unit and the driving transmission unit; and a lower surface portion connected to the variable unit, wherein the thickness of each of the friction units gradually increases. Claim 14 A transmission system according to claim 13, characterized in that as the radius of the friction transmission part increases, the upper surfaces of the friction units extend to each other to form a circular outer surface, and as the radius of the friction transmission part decreases, the lower surface of the friction unit is positioned outside the upper surface of the adjacent friction unit. Claim 15 A driving method of a transmission system according to any one of claims 1 to 3 and 5 to 14, wherein when the rotational speed of the driving unit is reduced by a command of the control unit, the shear torque increases due to the friction difference between the driving unit and the driving transmission unit, and the radius of the frictional transmission unit increases, thereby reducing the rotational speed of the driving transmission unit, and when the rotational speed of the driving unit is increased by a command of the control unit, the centripetal force of the frictional transmission unit increases, and the radius of the frictional transmission unit decreases, thereby increasing the rotational speed of the driving transmission unit.

Images