KR102470215B1 - Self-energizing clutch transferring restricted torque and hybrid vehicle using the same - Google Patents

Abstract

A friction clutch is provided which utilizes a magneto-reinforcing effect and in which the transmitted torque is limited.
The clutch device uses the screw-nut relationship to provide a self-reinforcing effect, and uses the inventive structure of the friction surface to limit the amount of torque transmitted. The clutch device does not take up much space compared to conventional hydraulic clutches, enables automatic shifting and mode change for optimal driving of hybrid vehicles, and eliminates the need for engine start motors in hybrid vehicles.

Description

Torque limiting self-reinforcing clutch and hybrid vehicle using the same {Self-energizing clutch transferring restricted torque and hybrid vehicle using the same}

The present invention relates to a friction clutch in which the transmitted torque is limited by using a magnetic reinforcing effect, and more specifically, by using the magnetic reinforcing effect, a required amount of torque can be transmitted with a small operating force, On the other hand, it is directed to a clutch of a friction type that can prevent the transmitted torque from increasing indefinitely.

Recently, a hybrid vehicle having a manual transmission has been developed, or there is a tendency to convert an existing vehicle into such a vehicle. When using the existing hydraulic clutch system in a manual transmission-hybrid vehicle, the following problems occur: 1) In order to implement the hybrid mode, the clutch disk must be automatically engaged and released according to the situation, but the manual transmission structure 2) The existing hydraulic clutch system takes up a lot of volume, so there is not enough space to add a drive electric motor, and 3) In the case of a hybrid vehicle with frequent engine on/off, start the engine There is a durability problem of the starter motor.

The present invention is to solve the above problems, and an object of the present invention is to provide a clutch device capable of solving problems that occur when using an existing hydraulic clutch system in a manual transmission-hybrid vehicle.

Furthermore, an object of the present invention is to provide a clutch device capable of transmitting a required amount of torque even with a small amount of operating force by using a self-reinforcing effect.

In order to solve the above problems, according to an aspect of the present invention, a friction clutch for disconnecting or connecting power transmission between a first shaft and a second shaft, comprising: a screw portion connected to the first shaft; a nut portion formed to engage with the screw portion; a first friction surface provided on the nut portion; a second friction surface engaged with the first friction surface and connected to a second shaft; and an operating unit for decelerating the rotational speed of the nut unit, wherein the screw unit and the nut unit move the nut unit toward the second friction surface when the rotational speed of the nut unit is smaller than the rotational speed of the first shaft. and wherein the first friction surface or the second friction surface is formed such that the vertical force between the first friction surface and the second friction surface is maintained constant after reaching a predetermined value. do.

When the first friction surface and the second friction surface are in a static friction state, power is transmitted from the first shaft to the second shaft, and the first friction surface and the second friction surface are in a kinetic friction state , power is transmitted from the second shaft to the first shaft.

When the first friction surface and the second friction surface are in a static friction state, the effective radius of the first friction surface or the second friction surface is reduced, and the first friction surface and the second friction surface have kinetic friction state, the effective radius of the first friction surface or the second friction surface is maintained constant.

A motor may be connected to the first shaft, and an internal combustion engine may be connected to the second shaft. The internal combustion engine does not have a starter motor. A transmission is connected to the first shaft in series with the motor.

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According to another aspect of the present invention, a hybrid vehicle including the aforementioned torque limiting self-reinforcing clutch is provided.

According to the present invention, there is provided a clutch device that does not take up much space.

In addition, according to the present invention, an automatic clutch device capable of automatically shifting and changing modes for optimal driving of a hybrid vehicle is provided.

Furthermore, according to the present invention, a clutch device that eliminates the need for a start motor of an engine in a hybrid vehicle is provided.

1 shows a torque limiting magnetic reinforcing clutch according to one embodiment of the present invention.
FIG. 2 schematically shows a contact state between the friction pad and the rotating member in the embodiment shown in FIG. 1 .
FIG. 3 shows a free body diagram of the screw portion and the nut portion shown in FIG. 2 and an equivalent free body diagram of the nut portion.
Figure 4 shows an embodiment according to the present invention for limiting the normal force applied to the rotating member by a friction pad.
FIG. 5 shows a relationship between changes in parameters and an operating state of the torque limiting magnetic reinforcing clutch according to an embodiment of the present invention shown in FIG. 4 .
6 shows a power transmission system of a hybrid vehicle.
FIG. 7 shows an embodiment of a clutch according to the present invention applied to the hybrid vehicle shown in FIG. 6 .
FIG. 8 is a view for explaining the operation of the power transmission system of the hybrid vehicle shown in FIG. 6 .
9 shows an experimental device for checking the operation of the torque limiting self-reinforcing clutch according to the present invention.
FIG. 10 shows physical quantities measured in the experimental apparatus shown in FIG. 9 .
FIG. 11 is a graph for analyzing the magnetic reinforcement effect of the torque limiting magnetic reinforcement clutch in the experimental device shown in FIG. 9 .
12 shows numerical analysis results for confirming the material of the nut part and the marginal interval between the friction pad and the rotating member.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. The same or similar reference numerals are given to the same or similar components, and overlapping descriptions thereof will be omitted. In describing the embodiments disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the embodiment disclosed in this specification, the detailed description thereof will be omitted. The accompanying drawings are only for easy understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the accompanying drawings, and all changes and equivalents included in the spirit and technical scope of the present invention It should be understood to include being or replacing.

Terms including ordinal numbers, such as first, second, etc., may be used to describe various elements, but these terms are used only for the purpose of distinguishing one element from another element, and the corresponding elements are those terms. not limited by Expressions in the singular number include plural expressions unless the context clearly dictates otherwise.

Terms such as "comprises", "includes" or "has" used herein should be understood to limit the presence of features, steps, elements or combinations thereof described in the specification, and one or more other It is not intended to exclude the possibility that features, steps, components, or combinations thereof may be present or added.

1 shows a torque limiting magnetic reinforcing clutch according to one embodiment of the present invention. The torque limiting self-reinforcing clutch 100 includes a screw portion 110 connected to the first shaft 10, a nut portion 120 engaged with the screw portion 110, and a first friction surface 131 provided on the nut portion. A rotating member having a friction pad 130 having a ) and a second friction surface 141 formed to be engaged with the first friction surface 131 of the friction pad 130 and connected to the second shaft 20 140, and an operating portion 150 for providing or releasing frictional force to the nut portion 120.

In the illustrated embodiment, the first shaft and the second shaft can rotate independently relative to each other. The screw part 110 is integrally formed on the outer circumferential surface of the first shaft 10 . Accordingly, the screw unit 110 has the same rotational speed as the first shaft 10 . The nut part 120 is engaged with the screw part 110 in a threaded manner. The nut part 120 is capable of reciprocating movement on the screw part 110 through relative motion with respect to the screw part 110 . In the illustrated embodiment, when the rotational speed of the nut part 120 is lower than the rotational speed of the screw part 110, that is, the first shaft, the nut part 120 is formed to move towards the rotating member 140.

A friction pad 130 is provided on one side of the nut part 120 . The friction pad 130 is fixed to the nut part 120 and rotates at the same speed as the nut part 120 . The friction pad 130 has a first friction surface 131 . A rotating member 140 connected to the second shaft 20 and rotating at the same speed is disposed at a position facing the nut part 130 . The rotating member 140 includes a second friction surface 141 formed to be engaged with the friction pad 130 .

The first shaft 10 is connected to the rotating member 140 via a bearing 30 . Accordingly, the first shaft 10 can rotate independently of the rotating member 140 and the second shaft 20 .

The operating portion 150 is configured to provide or release frictional force to the nut portion. In the illustrated embodiment, the operating unit 150 includes a solenoid 151 and a lever 152 capable of reciprocating movement by the solenoid 151 . The lever 152 moves to the left in the drawing to contact the friction surface 121 of the nut portion 120, or moves to the right in the drawing to release the contact state with the friction surface 121 of the nut portion 120. can

A brief description of the operation of the torque limiting self-reinforcing clutch 100 shown in FIG. 1 is as follows.

In a state where the lever 152 of the operating part 150 does not contact the friction surface 121 of the nut part 120, the first shaft 10, the screw part 110 and the nut part 120 rotate at the same time. rotate at speed The first friction surface 131 of the friction pad 130 and the second friction surface 141 of the rotating member 140 do not come into contact and remain spaced apart. The second shaft 20 and the rotating member 140 connected thereto may be in a stationary state or rotate at a speed different from that of the first shaft 10 .

When the lever 152 of the operating part 150 contacts the friction surface 121 of the nut part 120, frictional force is generated between the lever 152 and the friction surface 121, and the rotational speed of the nut part 120 becomes smaller with respect to the rotation speed of the first shaft 10 and the screw unit 110. When the nut part 120 is decelerated, the nut part 120 is moved toward the rotating member 140 along the axis of rotation of the first shaft 10, and the first friction surface 131 and the second friction surface 141 are come into contact When the two frictional surfaces come into contact, the nut portion 120 is further decelerated due to the frictional force and at the same time the movement in the direction of the rotating member 140 is constrained. Accordingly, a vertical force is applied to the rotating member 140 by the nut portion 120 . The applied vertical force increases the friction force acting between the first friction surface 131 and the second friction surface, which acts as a torque for the rotating member 140 . A torque having the same rotational direction as the rotational direction of the first shaft 10 is applied to the rotating member 140 , and angular acceleration is generated in the same direction as the rotational direction of the first shaft 10 .

In a state where the rotational speed of the nut part 120 is smaller than the rotational speed of the first shaft 10, the vertical force applied to the rotating member 140 by the nut part 120 continues to increase. In order to prevent damage to the device, this vertical force must be limited so that it does not increase beyond a certain value.

Hereinafter, with reference to FIGS. 2 to 5 , an embodiment according to the present invention for limiting the vertical force applied to the rotating member 140 by the nut unit 120 will be described. 2 schematically shows the screw portion 110, the nut portion 120, the friction pad 130, and the rotating member 140 in a state in which the friction pad 130 and the rotating member 140 are in contact, 3 shows a free body diagram of the screw portion 110 and the nut portion 120 and an equivalent free body diagram of the nut portion 120, and FIG. 4 shows an embodiment according to the present invention for limiting the vertical force. 5 shows the relationship between changes in the parameters of the torque limiting self-reinforcing clutch and the operating state in the embodiment according to FIG. 4 .

As shown in FIG. 2 , a reaction force N _p from the rotating member 140 is applied to the nut portion 120 at an effective contact radius r _p between the friction pad 130 and the rotating member 140 . Since movement of the nut part 120 in the x-axis direction is limited by the rotating member 140, the acceleration in the x-axis direction can be regarded as 0 (zero). Therefore, referring to the free body diagram shown in FIG. 3, from the equation of motion of the nut part 120 in the x-axis direction, the vertical force N _s between the screw part 110 and the nut part 120 is as follows given

Based on Equation 1, the torque applied to the nut unit 120 by the screw unit 110 can be expressed as Equation 2.

는 미끄러짐 효과를 포함한 마찰계수이다. 즉, 스크류부(110)가 너트부(120)에 인가하는 토크는 스크류부(110)의 고정 반경에 미끄러짐 효과를 포함한 마찰계수 그리고 수직력의 곱으로 나타낼 수 있다.In Equation 2,

is the coefficient of friction including the slip effect. That is, the torque applied to the nut part 120 by the screw part 110 can be represented by the product of the fixed radius of the screw part 110, the friction coefficient including the sliding effect, and the vertical force.

When the nut part 120 is replaced with a friction coefficient having a sliding effect and expressed as an equivalent free body diagram, it is expressed as 120a in FIG. 3 . In the equivalent free body diagram 120a of the nut portion, the vertical force is canceled and the torque by the friction pad 130 and the torque by the screw portion 110 remain. Due to both torques, the nut portion 120a transmits torque in a state in which slippage occurs on one side and no slippage on the other side, according to the principle of maximum static frictional force. Therefore, the sliding state of the nut part 120a can be divided into two types. In the first case, sliding occurs between the screw unit 110 and the nut unit 120, and no sliding occurs between the friction pad 130 and the rotating member 140. In this case, the torque transmitted to the rotating member 140 becomes the torque transmitted by the screw unit 110 . The second case is a case in which slippage does not occur between the screw portion 110 and the nut portion 120 and slippage occurs between the friction pad 130 and the rotating member 140 . In this case, the torque transmitted to the rotating member 140 becomes the torque transmitted by the friction pad 130 . In particular, in the second case, since sliding between the screw part 110 and the nut part 120 does not occur, the vertical force becomes constant and the torque transmitted to the rotating member 140 becomes constant.

The step in which the nut part 120 moves and the friction pad 130 contacts the rotating member 140 is the first case. 4 shows an embodiment for providing a second case in which the transmitted torque is constant. In the illustrated embodiment, in order to reduce the effective contact radius r _p between the friction pad 130 and the rotation member 140 by the vertical force, the clearance (d) between the friction pad 130 and the rotation member 140 ) is provided. In this configuration, when a normal force is applied to the friction pad 130, the friction pad 130 is deformed so that the outer diameter r ₂ of the contact surface remains constant, but the inner diameter r ₁ decreases, and thus the effective contact radius r _p decreases. The contact effective radius r _p decreases until the clearance distance (d) becomes 0 (zero).

5 shows changes in parameters in the first case (I) and the second case (II) described above. The torque transmitted by the clutch according to the embodiment shown in FIG. 4 decreases along arrow A in the first case (I) and remains constant along arrow B in the second case (II). The contents described above are the torque limiting magnetic reinforcement principle of the clutch according to the present invention.

6 to 8 show cases in which the clutch according to the present invention is applied to a hybrid vehicle. 6 shows a power transmission system of a hybrid vehicle, FIG. 7 shows an embodiment of a clutch according to the present invention applied to the hybrid vehicle shown in FIG. 6, and FIG. 8 shows the hybrid vehicle shown in FIG. It is a drawing for explaining the operation of the power transmission system.

As shown in FIG. 6 , the parallel hybrid power transmission system includes an engine, a clutch 100a, a motor, and a transmission, and does not include a start motor for the engine. In hybrid vehicles, engine starting and mode switching are frequent. In the illustrated embodiment, the engine is started using a traction motor or driving inertia of a power transmission system instead of a start motor. To this end, the clutch 100a according to an embodiment of the present invention is applied. 7 shows an exploded view of the clutch 100a. The clutch 100a has the same technical configuration as the clutch 100 shown in FIG. 1 except that it has a one-way clutch 710 instead of the bearing 30. The first shaft 10 is connected to the motor, and the second shaft (not shown) is connected to the engine.

The operation of the clutch 100a is largely divided into a process of reverse torque transmission (transmission of power in the direction of arrow A in FIG. 6) and a process of forward transmission of torque (transmission of power in the direction of arrow B in FIG. 6).

In the reverse torque transfer process, the engine is started through the driving inertia or the traction motor and the friction pad 130. In the first EV mode, the rotating member 140 and the friction pad 130 are not engaged, the one-way clutch 710 is idle, and the transmission and engine are disconnected. When the vehicle reaches the engine starting reference speed, the solenoid 150 pushes the stick to decelerate the nut with small friction, and engages the friction pad 130 and the rotating member 140. Thereafter, the nut portion 120 is decelerated due to friction between the rotating member 140 and the friction pad 130 . The engine is started by applying ignition in a state in which torque is transmitted to the rotating member 140 . When the engine is started, the engine speed is switched to HEV mode where the speed of the vehicle drive system is smoothly taken over. Torque is transmitted from the engine to the transmission, and this is the torque forward transmission process. Thereafter, the one-way clutch 710 is engaged, and assist assisted by the motor is possible while the engine transmits torque to the power transmission system.

8 is a view for explaining that each device of a hybrid vehicle power transmission system operates in conjunction with each other. In the uppermost graph, the dotted line represents the change in engine RPM with time, and the solid line represents the load RPM representing the speed of the transmission input shaft according to the vehicle load. In the second and third graphs, the solenoid and engine start flag are shown respectively. When the transmission input shaft of the vehicle reaches 500 RPM (t1), the solenoid is driven to engage the friction pad 130 with the rotating member 140 (t2). Then, the speed of the engine gradually increases through the torque transfer process. When the engine ignition speed is reached, the engine is ignited and started (t3). When the speed of the engine gradually increases and becomes faster than the load RPM, the engine takes over the speed of the vehicle through the one-way clutch and smoothly engages in speed (t4). After this, the HEV mode is reached through a torque forward transfer process.

9 to 12 show matters related to experiments to check the operation of the torque limiting magnetic reinforcing clutch according to the present invention. 9 is a photograph of the experimental device, FIG. 10 shows physical quantities measured in the experimental device shown in FIG. 9, and FIG. 11 analyzes the magnetic strengthening effect of the torque limiting self-reinforcing clutch in the experimental device shown in FIG. 12 shows the numerical analysis results for confirming the material of the nut part and the clearance between the friction pad and the rotating member.

The experimental apparatus includes a rod motor 910, an engine motor 920 for simulating an engine, a flywheel 930 for simulating vehicle inertia, a torque sensor 940 for measuring torque in the reverse transmission process, and for experiments. It is configured to include a designed torque limiting magnetic reinforcing clutch (100b). Although not shown, a spring is provided to ensure the return of the lever when the solenoid is turned OFF.

10 shows speed, torque, and solenoid ON/OFF states along the time axis. In the speed graph, red indicates the speed of the rod motor and blue indicates the speed of the engine motor. First, it can be confirmed that slippage occurred after the solenoid was turned ON and the clutch delivered a torque of up to 25 Nm (A). Although there is some vibration, it can be confirmed that the torque transmitted after the slip occurs converges to a certain extent, as expected in the torque transmission method. After the reverse torque transfer process, the engine motor is assumed to be in a running state and the speed gradually increases. It can be seen that the engine motor, which has become faster than the road motor, smoothly takes over the vehicle speed and enters the torque transfer process (B). In addition, since the engine motor transfers torque through a torque forward transfer process, it can be confirmed that negative torque is measured by the torque sensor (C).

According to the catalog, the solenoid exerts a vertical force of about 75 N (in Fig. 11, travel stroke 8 mm, power consumption 120 W). Considering the point of application of the force, the vertical force applied to the center of the friction pad is estimated to be about 37.5N, which is about half of 75N. Considering the tensile force of the spring, the vertical force applied to the pad by the solenoid is (37.5 - α) N. However, the normal force actually applied to the friction pad becomes normal force = torque / (static friction coefficient * radius of friction pad r2) = 25 N m / (0.55 * 0.082 m) = 554 N. Considering the effective radius after being deformed by the normal force, since the radius decreases more than 0.082 m, the normal force actually applied to the friction pad becomes (554 + β) N. In summary, it can be seen that the self-reinforcing effect is equal to or greater than the vertical force = the actual applied vertical force - the vertical force by the solenoid = (554 + β) - (37.5 - α) = 516.5 N.

As a result of the simulation of FIG. 12 , it was confirmed that the central portion of the pad was deformed and the contact area increased as the vertical force was applied. The contact outer diameter of the pad remained the same at 84 mm, but the inner diameter decreased from 84 mm to 33 mm, confirming that the effective radius of the friction pad decreased to about 62 mm. The material of the nut part was found to be preferably aluminum.

The foregoing detailed description should not be construed as limiting in any way and should be considered illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

10: 1st axis
20: 2nd axis
30: bearing
100, 100a, 100b: Torque limiting self-reinforcing clutch
110: screw part
120: nut part
121: friction surface
130: friction pad
131: first friction surface
140: rotating member
141: second friction surface
150: operation part
151: solenoid
152: lever
910: load motor
920: engine motor
930: fly wheel
940: torque sensor

Claims (9)

A friction clutch that disconnects or connects power transmission between a first shaft and a second shaft,
A screw part connected to the first shaft;
a nut portion formed to engage with the screw portion;
a first friction surface provided on the nut portion;
a second friction surface engaged with the first friction surface and connected to a second shaft; and,
Operating unit for reducing the rotational speed of the nut unit
Including,
The screw part and the nut part are formed so that the nut part moves toward the second friction surface when the rotational speed of the nut part is smaller than the rotational speed of the first shaft,
The first friction surface or the second friction surface is formed so that the normal force between the first friction surface and the second friction surface remains constant after reaching a predetermined value.
Torque limiting self-reinforcing clutch.
The method of claim 1,
When the first friction surface and the second friction surface are in a static friction state, power is transmitted from the first shaft to the second shaft;
When the first friction surface and the second friction surface are in a kinetic friction state, power is transmitted from the second shaft to the first shaft
A torque limiting self-reinforcing clutch, characterized in that.
The method of claim 1,
When the first friction surface and the second friction surface are in a static friction state, the effective radius of the first friction surface or the second friction surface is reduced,
When the first friction surface and the second friction surface are in a kinetic friction state, the effective radius of the first friction surface or the second friction surface is maintained constant.
A torque limiting self-reinforcing clutch, characterized in that.
delete The method of claim 1,
A motor is connected to the first shaft, and an internal combustion engine is connected to the second shaft.
A torque limiting self-reinforcing clutch, characterized in that.
The method of claim 5,
The internal combustion engine does not have a start motor.
A torque limiting self-reinforcing clutch, characterized in that.
The method of claim 5,
In the first shaft, a transmission is connected in series with the motor
A torque limiting self-reinforcing clutch, characterized in that.
delete A hybrid vehicle comprising the torque limiting self-reinforcing clutch according to any one of claims 1 to 3 and 5 to 7.

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