JP2023157455A - drive mechanism - Google Patents

Abstract

To provide a drive mechanism which has an excellent lock function, is saved in electric power, and is simple.SOLUTION: A drive mechanism K includes a motor M having a drive shaft Ma, and a speed reduction part G which has a first shaft s1 receiving rotation of the drive shaft Ma, and transmits the rotation to a driving object while reducing the speed of the rotation. The drive mechanism K further includes a switch part C which switches, in coordination with the rotation of the drive shaft Ma, between an unlock state in which the rotation of the first shaft s1 is allowed in the rotation of the drive shaft Ma, and a lock state in which the rotation of the first shaft s1 is regulated in a stop of the drive shaft Ma.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a drive mechanism including a motor and a deceleration section that decelerates and transmits the drive rotation of the motor to a driven object.

Conventionally, as such a drive mechanism, there is one shown in Patent Document 1, for example (see [0006] to [0007] and FIG. 3).

This drive mechanism is a steer-by-wire steering device that converts the rotation of the output shaft of the steering actuator into a linear motion using a linear motion mechanism and transmits this to a steering link mechanism. In this device, an outer ring member 13 is disposed concentrically with the outer diameter side of the rotary output shaft 7, a carrier 14 is rotatably supported with respect to the rotary output shaft 7, and a planetary roller 16 supported on the carrier 14 is provided. is screwed onto the outer ring member 13.

The planetary roller 16 and the outer ring member 13 are screwed together by a spiral protrusion 25 and a circumferential groove 26, and the rotation and revolution of the planetary roller 16 is converted into axial movement, and the outer ring member 13 or the rotation output shaft is Each planetary roller 16 moves relative to 7 in the axial direction. The axial movement of the outer ring member 13 in response to the relative movement of each planetary roller 16 is transmitted to the arm of the steering link mechanism, and the steered wheels are steered.

According to this configuration, rotation of the rotation output shaft of the steering actuator is converted into axial movement of the outer ring member by rotation and revolution of the planetary roller. Therefore, the planetary roller mechanism not only functions as a conversion mechanism that converts rotational force into linear motion, but also plays the role of a speed reducer, making it possible to downsize and shorten the axial length. As a result, the steering mechanism of the steer-by-wire steering system can be housed in the wheel house, and a large interior space can be secured. In addition, by using planetary rollers as a conversion mechanism that converts rotational force into linear motion, it is possible to hold the load, prevent reverse input from the steered wheels when the vehicle is moving straight, and save power. be.

JP2013-95310A

In the conventional drive mechanism described above, in order to prevent reverse input from the steered wheels when the vehicle is moving straight, etc., the cross sections of the spiral protrusions 25 and the circumferential grooves 26 on the planetary rollers 16 and the outer ring member 13 are flat. It is said to be the shape. However, in the case of this configuration, there were problems such as a decrease in mechanical efficiency until the drive rotation from the rotary output shaft is converted into direct motion, and an increase in the size of the motor.

As described above, the above-mentioned conventional drive mechanisms have various problems that need to be solved, and there is a need for a simple and power-saving drive mechanism that exhibits a good locking function when the driven object is not in operation. was.

(Characteristic configuration)
The characteristic configuration of the drive mechanism according to the present invention is as follows:
a motor having a drive shaft;
comprising an input shaft that receives the rotation of the drive shaft, and a deceleration unit that decelerates the rotation and transmits it to the driven object,
Switching in conjunction with the rotation of the drive shaft, an unlocked state in which rotation of the input shaft is allowed when the drive shaft rotates, and a locked state in which rotation of the input shaft is restricted when the drive shaft is stopped. The point is that it has a section.

(effect)
In the drive mechanism of this configuration, the switching portion is maintained in a locked state in a non-energized state in which the motor is not driven. Therefore, when controlling a driven object that is normally maintained in a non-energized state, it is possible to save power.

Furthermore, since a single motor performs the locking and unlocking operations of the switching section and the output to the deceleration section, the number of components is reduced and costs can be reduced.

(Characteristic configuration)
In the drive mechanism according to the present invention, the switching section includes at least one friction plate that rotates as a result of the motor, a pressing plate that is arranged to face the friction plate, and pressing the pressing plate against the friction plate. It is advantageous to include a clutch having a biasing member that does this, and a rotation-linear conversion unit that is provided coaxially with the rotation axis of the friction plate and releases the pressure on the press plate.

(effect)
In this configuration, when the drive shaft of the motor is not rotating, the press plate is pressed against the friction plate and the input shaft is in a locked state. However, when the motor operates, the drive shaft rotates, and the rotation-linear conversion section releases the pressing of the press plate. With a press-type clutch using such a biasing member, the device can be easily miniaturized and a drive mechanism with excellent mountability can be obtained.

Furthermore, since the rotational-linear conversion section is arranged coaxially with the rotational axis of the friction plate, the dimensions of the switching section, particularly in the radial direction, can be easily reduced, and the drive mechanism can be downsized.

Furthermore, since the clutch is coaxial with the drive shaft of the motor, it is easy to configure the connection part to directly transmit the rotational driving force of the motor to the clutch, making it possible to obtain a drive mechanism with good mechanical efficiency. can.

(Characteristic configuration)
In the drive mechanism according to the present invention, the rotation-linear conversion section is held by either the drive shaft or the press plate and rotates around the axis of the drive shaft. It can be configured to include a ball and a cam surface formed on one or both of the drive shaft and the press plate.

(effect)
If the clutch includes a cam surface and a ball as in this configuration, the pressure on the press plate can be easily released due to the effect of the cam surface as the drive shaft rotates. The cam surface is provided on a member of the drive shaft and the press plate opposite to the side that holds the ball, but it can also be provided on the side that holds the ball. Since the ball rolls against the cam surface, friction loss can be reduced by providing cam surfaces on both members. This arrangement of the cam surface and the ball is relatively simple. Therefore, it becomes easy to install a clutch with a simplified configuration and reduced size.

Further, by adjusting the inclination angle of the cam surface, it is easy to set the engagement/disengagement responsiveness of the clutch to the rotation angle of the drive shaft. Therefore, the application targets of the drive mechanism can be expanded.

(Characteristic configuration)
In the drive mechanism according to the present invention, the switching section may include a second motor that operates the pressing plate.

(effect)
In this configuration, a dedicated second motor is provided to unlock the switching section. The driving timing of such a second motor can be set freely according to the driving timing of the main motor. Therefore, for example, after unlocking is performed by the second motor, it is possible to immediately output the rotational drive of the main motor to the deceleration section, thereby providing a drive mechanism with excellent control responsiveness.

A sectional view showing the drive mechanism according to the first embodiment A perspective view showing the main parts of the clutch according to the first embodiment A sectional view showing a drive mechanism according to a second embodiment

[First embodiment]
(overview)
The drive mechanism K according to the present invention is used, for example, as an actuator for an electric steering device of a vehicle. The electric steering device is incorporated in, for example, a steering link 1 of a front wheel or a rear wheel, and the direction of the wheels is determined by adjusting the length of a linear motion part 2 by driving a motor M.

A drive mechanism K according to this embodiment is shown in FIGS. 1 and 2. The drive mechanism K includes a motor M and a speed reduction section G so as to drive the linear motion section 2 of the steering link 1 that is a driving target. The linear motion part 2 includes a cylindrical member 2a that rotates on the outside, and a linear motion member 2b that is screwed into the interior of the cylindrical member 2a via a ball screw 3 and moves back and forth. A part of the linear motion member 2b is provided with, for example, a convex guide portion 2b1, and the guide portion 2b1 is guided by the groove portion 1a formed on the inner surface of the steering link 1, so that the linear motion member 2b is rotated. It is possible to move back and forth without moving. A large-diameter gear g4 is provided on the outer circumference of the cylindrical member 2a, and is driven by the output gear g3 of the reduction section G. Incidentally, this cylindrical member 2a and the large diameter gear g4 function as the third shaft s3 of the reduction section G.

(reduction part)
The speed reducer G includes a first shaft s1, which is an input shaft s1 driven by a drive shaft Ma of a motor M, which will be described later, and a second shaft s2, which has an output gear g3. Both the first shaft s1 and the second shaft s2 are supported by bearings at both ends. A first gear g1 with a small diameter is provided on the first shaft s1, and a second gear g2 with a large diameter is provided on the second shaft s2. The second shaft s2 is further provided with a small-diameter output gear g3, which meshes with a large-diameter gear g4 of the cylindrical member 2a, which is the third shaft s3. In this way, the speed reducer G of this embodiment has a three-stage gear train.

The gears of the reduction unit G are all spur gears and have a simple structure. If the spur gear is used, there is less friction due to gear meshing, and a highly efficient gear transmission mechanism can be obtained.

(motor)
The rotational drive from the drive shaft Ma of the motor M is input to the first shaft s1 of the deceleration section G. The configuration of the motor M is arbitrary, and for example, various DC motors driven at 12V are used. The motor M is driven by a separately provided control unit ECU, with the rotation speed and rotation direction set according to various operating conditions.

(clutch)
It is desirable that the linearly moving member 2b is completely stopped when no steering instruction is issued. However, the reverse input acting on the steering link 1 etc. from the wheels tends to cause the reduction unit G and the drive shaft Ma of the motor M to rotate in a driven manner. The reverse input acting on the translational member 2b causes the cylindrical member 2a to rotate through the ball screw 3. Since the speed reducer G that meshes with the cylindrical member 2a is constituted by a spur gear, the second shaft s2 and the first shaft s1 are also easily driven to rotate. Furthermore, the drive shaft Ma of the motor M that is interlocked with the first shaft s1 may also be driven to rotate when the motor M is not energized.

Therefore, this embodiment includes a switching section C that prevents the driven rotation. The switching unit C is a so-called clutch C1, and includes at least one friction plate P that rotates as a result of a motor M, a pressing plate Q that is arranged opposite to this friction plate P, and an attachment that presses this pressing plate Q against the friction plate P. A rotation-linear conversion section is formed which includes a biasing member F and is provided coaxially with the rotation axis X of the friction plate P to release the pressure of the press plate Q.

Due to this switching part C, when the drive shaft Ma of the motor M rotates, the pressure between the press plate Q and the friction plate P is released, and an unlocked state is established in which rotation of the first shaft s1 is allowed. Further, when the drive shaft Ma is stopped, the press plate Q is pressed against the friction plate P, and the rotation of the first shaft s1 is regulated to be in a locked state.

More specifically, as shown in FIGS. 1 and 2, a friction plate support H is provided between the drive shaft Ma and the first shaft s1. The friction plate support H has a disk-shaped base H1, and a cylindrical boss H2 on one side of the base H1. The first shaft s1 is slidably engaged inside the boss portion H2.

A plurality of cam surfaces C1a are formed on the other surface of the base H1 along the circumference of the rotation axis X of the first shaft s1. The cam surface C1a is formed as a V-shaped recess, and the center along the circumferential direction is low and both sides are high. A ball C1b is in contact with each of the cam surfaces C1a, and the ball C1b is held in a recess Ma1 formed in the end surface of the drive shaft Ma. That is, when the drive shaft Ma rotates in either the forward or reverse direction, the ball C1b is driven to rotate, and the ball C1b rides on either the left or right side of the V-shaped cam surface C1a. As a result, the friction plate support H is pushed toward the first axis s1 along the rotation axis X.

As the angle of the cam surface C1a increases, the amount of extrusion of the base H1 relative to the rotation angle of the drive shaft Ma increases, so that the pressure between the friction plates P, which will be described later, can be quickly released.

Alternatively, the cam surface C1a may be formed on the end surface of the drive shaft Ma, and the ball C1b may be held on the base H1. Further, although the cam surface C1a is provided on a member of the drive shaft Ma and the pressing plate Q that is opposite to the side that holds the ball C1b, it can also be provided on the side that holds the ball C1b. Since the ball C1b rolls against the cam surface C1a, friction loss can be reduced by providing the cam surface C1a on both members.

In this way, if the clutch C1 includes the cam surface C1a and the ball C1b, the pressure on the press plate Q can be easily released due to the effect of the cam surface C1a accompanying the rotation of the drive shaft Ma. In addition, such arrangement of the cam surface C1a and the ball C1b is relatively simple. Therefore, it becomes easy to install the clutch C1, which has a simplified configuration and is miniaturized. Further, by adjusting the inclination angle of the cam surface C1a, it is easy to set the engagement/disengagement responsiveness of the clutch C1 to the rotation angle of the drive shaft Ma. Therefore, the application targets of the drive mechanism K can be expanded.

As shown in FIG. 2, the base H1 is in contact with the annular pressing plate Q via the thrust bearing 4. The pressing plate Q is constantly urged toward the base H1 by a plurality of urging members F that take a reaction force at the bottom of the housing 5. Here, a coil spring Fa is used as the biasing member F, and a holding hole 6 is formed in the housing 5 and the pressing plate Q to receive the coil spring Fa. The depth of this holding hole 6 is set to such an extent that even if the pressing plate Q is pushed back until it comes into contact with the housing 5, the coil spring Fa will not completely contract inside the holding hole 6.

The outer circumferential surface of the base H1 is approximately cylindrical, and has at least one convex portion 7 extending along the rotation axis X. A plurality of friction plates P are arranged on the outer peripheral side of the base H1. There are two types of friction plates P, one of which is a first friction plate P1 that has at least one notch 8 on the annular inner edge side and is configured to engage with the convex portion 7 of the base H1. The other is a second friction plate P2 having a notch 8 on the annular outer edge. At least one convex portion 7 also extends from the inner surface of the housing 5 along the rotation axis X, and the notch 8 of the second friction plate P2 engages with this convex portion 7.

That is, the pressing plate Q presses the first friction plate P1 and the second friction plate P2 by the biasing member F, thereby preventing the relative rotation of both friction plates P, and the central base H1 becomes in a locked state. A second friction plate P2 is disposed on the outermost side that contacts the press plate Q so that the press plate Q does not rotate.

By including the clutch C1 described above, in the drive mechanism K, the switching portion C is maintained in a locked state in a non-energized state in which the motor M is not driven. Therefore, since the power is always maintained in a non-energized state, power saving can be improved.

If the clutch C1 is a press-type clutch C1 using the biasing member F, it is possible to easily downsize the clutch C1 and obtain a drive mechanism K with excellent mountability.
In addition, since one motor M performs the locking and unlocking operations of the switching section C and the output to the deceleration section G, the number of components is reduced and costs can be reduced.

Since the clutch C1, which is a rotational-linear motion converter, is arranged coaxially with the rotational axis X of the friction plate P, the dimensions of the clutch C1, especially in the radial direction, can be easily reduced, and the drive mechanism K can be made smaller. It is possible to In addition, since the clutch C1 is provided coaxially with the drive shaft Ma of the motor M, it is easy to configure the connection part to directly transmit the rotational driving force of the motor M to the clutch C1, resulting in a mechanically efficient drive. Mechanism K can be obtained.

[Second embodiment]
FIG. 3 shows a second embodiment of the invention. Here, the switching section C is arranged on the outside, and the deceleration section G, the motor M, and the switching section C are arranged in this order. The configurations of the speed reducer G and the motor M are the same, and the base H1 is slidably engaged with the drive shaft Ma of the motor M. A first friction plate P1 and a second friction plate P2 are arranged on the outer periphery of the base H1, and a press plate Q is in contact with the second friction plate P2. A biasing member F is provided between the housing 5 and the pressing plate Q. However, the operating mechanism of the switching section C is different from that of the first embodiment.

Here, the second motor M2 is used as the switching section C. The second motor M2 is provided further outside the switching section C, and a second drive shaft Ma2 of the second motor M2 is screwed into the press plate Q. A male threaded portion 9 is formed at the tip of the second drive shaft Ma2, and a female threaded portion 10 screwed into the male threaded portion 9 is formed on the inner surface of a boss portion H2 formed at the center of the pressing plate Q. The pitch of the male threaded portion 9 and the female threaded portion 10 is appropriately set so that the pressing plate Q can move quickly when the second drive shaft Ma2 rotates. In this case, when the second motor M2 is de-energized, the position of the press plate Q may become unstable. However, in this embodiment, since the pressing member F constantly urges the pressing plate Q toward the second friction plate P2, even if the second motor M2 is de-energized, the switching part C is It is possible to maintain the locked state.

The operation of the second motor M2 is controlled by the control unit ECU. At this time, the second motor M2 is rotated in forward and reverse directions in synchronization with the motor M. As a result, the pressing state of the pressing plate Q against the second friction plate P2 changes, and the switching portion C switches between the locked state and the unlocked state.

With this configuration, the rotation of the speed reducer G can be regulated when the second motor M2 is de-energized, and when the motor M is driven to change the state of the steering link, the second motor M2 After the lock is released, the rotational drive of the motor M can be immediately outputted to the reduction unit G, and a drive mechanism K with excellent control responsiveness can be obtained.

[Other embodiments]
In the second embodiment, if the pitch between the male threaded portion 9 and the female threaded portion 10 is small and it is difficult for the second drive shaft Ma2 to rotate due to reverse input from the motor M, the biasing member F may be omitted. . In other words, if the second motor M2 is driven to stop energizing the pressing plate Q while pressing it against the second friction plate P2, and the pressing state of the pressing plate Q is maintained as it is, the biasing member F is unnecessary. Become.

In the clutch C1, after the pressure between the friction plates P is released, it is preferable that the rotational drive of the drive shaft Ma is efficiently transmitted to the base H1. For this purpose, it is preferable to provide an abutment surface between the end surface of the drive shaft Ma and the surface of the base H1 so that rotational force can be transmitted to each other along the circumferential direction. In other words, after the pressure between the friction plates P is released by the ball C1b and the cam surface C1a, the contact surfaces of the friction plates P come into contact with each other in a state where the drive shaft Ma is further rotated. This allows the rotational driving force to be transmitted from the drive shaft Ma to the base H1, and prevents the ball C1b and the cam surface C1a from receiving rotational driving torque. This reduces wear and the like on the ball C1b and the cam surface C1a, and improves the durability of the clutch C1 portion.

The drive mechanism of the present invention can be widely used in various actuators that operate a driven object using a motor and a speed reducer.

C Switching part C1 Clutch C1a Cam surface C1b Ball F Biasing member G Reduction part K Drive mechanism M Motor Ma Drive shaft M2 Second motor P Friction plate Q Pressing plate s1 Input shaft X Rotation axis center

Claims (4)

a motor having a drive shaft;
comprising an input shaft that receives the rotation of the drive shaft, and a deceleration unit that decelerates the rotation and transmits it to the driven object,
Switching in conjunction with the rotation of the drive shaft, an unlocked state in which rotation of the input shaft is allowed when the drive shaft rotates, and a locked state in which rotation of the input shaft is restricted when the drive shaft is stopped. A drive mechanism with parts. The switching unit includes at least one friction plate that rotates as a result of the motor, a pressing plate that is arranged opposite to the friction plate, an urging member that presses the pressing plate against the friction plate, and rotation of the friction plate. 2. The drive mechanism according to claim 1, further comprising a clutch having a rotational-linear conversion section that is provided coaxially with an axial center and releases the pressing force of the pressing plate. The rotation-linear conversion unit includes at least one ball that is held on either one of the drive shaft and the press plate and rotates around the axis of the drive shaft; The drive mechanism according to claim 2, further comprising a cam surface formed on one or both of the surfaces. The drive mechanism according to claim 2 or 3, wherein the switching section includes a second motor that operates the press plate.

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