JP2014190436A - Electric actuator for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an electric actuator to be mounted on a vehicle have a linear compact structure, and to enable the electric actuator to accurately control a speed and a position and to properly cope with failures.SOLUTION: An electric motor 2 including a hollow sleeve-shaped rotor 3 is installed on an electric actuator for a vehicle having a cylindrical housing 1. A screw shaft 4 engaged with a nut member 5 via balls, is disposed in the sleeve-shaped rotor 3, and the screw shaft 4 is reciprocated by rotation of the nut member 5 connected to the sleeve-shaped rotor 3, to drive an object. A brake mechanism 6 and a decelerating mechanism 7 are disposed between the electric motor 2 and the nut member 5, and the brake mechanism 6 is automatically operated to stop the screw shaft 4 at a correct position when the sleeve-shaped rotor 3 comes to a prescribed rotating position. The brake mechanism 6 can be manually released, so that it is manually released to move the screw shaft 4, when the brake is kept actuated due to a failure.

Description

  The present invention relates to an electric actuator mounted on a vehicle in order to drive a movable part or work equipment mounted on the vehicle.

  In many cases, vehicles are equipped with various movable parts or work equipment having movable parts. For example, a truck bed, which is a vehicle for freight transportation, has a cargo bed called a wing body that has a movable roof and can be loaded and unloaded from the side of the bed. In the wing body, the roof panel divided into right and left along the center line in the longitudinal direction of the loading platform forms a wing integrally with the side panel, and the left and right wings are centered on the hinge at the center of the roof of the loading platform. Is opened and closed in a flip-up manner by the actuator. As an actuator for opening and closing the wing, a hydraulic cylinder that operates by hydraulic pressure is usually used.

  The structure of a general wing body mounted on a truck is shown in FIG. A front panel 101 is disposed at the front of the loading platform, a rear frame 102 is disposed at the rear, and a double door rear door 103 is attached to the rear frame 102. Two wings 104 are arranged in the upper part, and these have an L-shaped cross section in which the divided roof panel 141 and one of the left and right side panels 142 are integrated. Below the side surface of the loading platform, a turn plate 105 is pivotally attached to the lower side by a hinge 106.

As an actuator for opening and closing the wing 104, two hydraulic cylinders 107 are installed to connect the rear frame 102 and the left and right wing roof panels 104, respectively. It is also installed at the top. When the hydraulic oil supplied to the hydraulic cylinder 107 is controlled and its rod is extended, as shown by the solid line in the figure, the wing 104 moves upward to open the side surface of the loading platform, and when the rod of the hydraulic cylinder 107 is shortened, As indicated by a two-dot chain line, the lower end portion of the side panel 142 of the wing 104 is in close contact with the upper end portion of the turn plate 105, and the loading platform is closed.
The opening / closing speed of the wing 104 is controlled in accordance with its position, and at the start of opening, the rainwater is prevented from getting caught in the negative pressure generated inside the cargo bed, and at the end of closing of the wing 104. Further, the opening / closing speed becomes a slow speed or a slow speed so that the lower end portion of the side panel 142 does not impactly contact the upper portion of the turn plate 105. Such a wing opening / closing operation method and a control circuit therefor are disclosed in Japanese Patent No. 4416805, which is a prior application of the present applicant.

As shown in FIG. 4, in a wing body that opens and closes a wing using a hydraulic cylinder as an actuator, it is necessary to provide a hydraulic pipe for supplying hydraulic pressure to the hydraulic cylinder, and an electric motor that drives a hydraulic pump for generating hydraulic pressure is also provided. As a result, the entire wing opening and closing device is complicated. In order to avoid this, it is also known to open and close the wing using an electric actuator, that is, an actuator that rotates a shaft formed with a screw by an electric motor and directly advances and retracts a member fitted to the screw. As an example, it is shown in Japanese Utility Model Publication No. 6-61543.
As shown in FIG. 5, the electric actuator described in this publication has a structure in which a sleeve-like sliding cylinder 202 is fitted in a cylindrical housing 201, and an end 203 of the housing 201 is a rear frame of the wing body. In addition, the end portion 204 of the sliding cylinder 202 is connected to a wing which is a movable portion (a driving object). A screw shaft 205 formed with a screw is installed at the center of the housing 201, and a nut member 206 that fits into the screw shaft 205 is fixed to the sliding cylinder 202. Thus, the sliding cylinder 202 is configured to reciprocate. An electric motor 207 having a rotating shaft parallel to the screw shaft 205 is attached to the outside of the housing 201, and the rotating shaft of the electric motor 207 is connected to the screw shaft 205 via a reduction gear train 208.

  The electric actuator described above is used as an actuator for opening and closing the wing in the wing body, but the electric actuator can naturally be used for other devices. Some trucks, which are vehicles for freight transportation, are equipped with a tailgate, which is a work device for loading and unloading cargo.Electric actuators have a cargo loading platform between the loading platform and the ground at the tailgate. It can also be used as an actuator that moves up and down in between.

Japanese Patent No. 4416805 Japanese Utility Model Publication No. 6-61543

An electric actuator is an actuator that converts the rotation of an electric motor directly into a reciprocating motion of a rod or the like only by a mechanical mechanism, and does not intervene a fluid portion like a hydraulic cylinder, so that the apparatus is simplified. Maintenance and inspection work is also facilitated.
However, in the electric actuator, since the electric motor as a power source is integrated with the actuator, it is difficult to make the actuator large and compact. In particular, an actuator mounted on a vehicle, for example, a wing opening / closing actuator mounted on the upper portion of the frame of the wing body is desirably small and compact because the mounting space is very limited. In the electric actuator described in Patent Document 2, the electric motor is attached so as to project to the side of the actuator. When the electric motor is attached to the wing body, the part of the cargo bed on which the cargo is loaded is reduced.

In addition, since many rotors (armatures) of electric motors are heavy and have a large moment of inertia, it is difficult to accurately control the stop position of the actuator only by controlling energization of the electric motor. For accurate control of the stop position, it is effective to combine a brake mechanism with the electric motor and automatically apply a braking force when the electric power to the electric motor is cut off. However, if a brake mechanism that operates in this way is incorporated in an electric actuator, the position of a drive object such as a wing remains fixed if a failure occurs in an electric motor or power distribution system. The object cannot be manually moved to a position suitable for repairing the failure. If the vehicle is equipped with an electric actuator, the vehicle does not have a large-scale repair device, so if a failure occurs on the road, it is difficult to bring it into a repair shop for repair. Fall into.
The problem of the present invention is that the electric actuator mounted on the vehicle has a small and compact structure having a linear shape, and it is possible to cope with the failure simultaneously with accurate control of the speed and position of the driven object. The present invention is configured to solve the above-described problems.

In view of the above-described problems, the present invention provides an electric actuator for a vehicle including an electric motor capable of rotating forward and reverse, and a brake with a manual release device provided with a hollow rotor through which a screw shaft passes. The mechanism and the speed reduction mechanism for rotating the nut member are arranged coaxially. That is, the present invention
“Electric motor in which a screw shaft formed with a screw and a nut member fitted to the screw are installed, and the screw shaft is reciprocated by rotating the nut member by an electric motor capable of normal / reverse rotation fixed to a housing. An actuator,
The electric actuator is installed in a vehicle,
The electric motor includes a hollow sleeve-like rotor through which the screw shaft passes, and the sleeve-like rotor is connected to the nut member via a speed reduction mechanism in which the rotation center axis of the input / output shaft is coaxial. And
A brake mechanism is provided between the sleeve-like rotor and the speed reduction mechanism to automatically apply a braking force when the electric motor is de-energized. The brake mechanism can be released manually. Is
The electric actuator is characterized by this.

  According to a second aspect of the present invention, the brake mechanism is driven by a non-excited dry single plate brake, that is, a brake disc fixed to the sleeve-like rotor, and a friction plate pressed against the brake disc. It is preferable to provide a brake mechanism having a pressing spring for applying power and an exciting coil for separating the brake disk and the friction plate during energization of the electric motor.

  Preferably, a ball is interposed between the nut member and a screw formed on the screw shaft.

  According to a fourth aspect of the present invention, the housing can be provided with a rotational position detector that detects the rotational position of the electric motor and a motor control device that controls the electric motor. When the electric actuator is a wing opening / closing actuator for a wing body, the motor control device is provided with a synchronous control unit that drives a plurality of actuators synchronously as described in claim 5. It is preferable.

In the electric actuator of the present invention installed in a vehicle, an electric motor capable of normal rotation and reverse rotation fixed inside the housing of the electric actuator is installed as a power source. This electric motor includes a hollow sleeve-like rotor, and a screw shaft connected to a driving object such as a wing passes through the sleeve-like rotor. The nut member fitted to the screw of the screw shaft is connected to the sleeve-like rotor via a speed reduction mechanism having a coaxial rotation center.
When the sleeve-like rotor is rotated by the electric motor, the nut member is rotated at the rotational speed reduced by the reduction mechanism, and the screw shaft passing through the sleeve-like rotor is displaced. Thus, in the electric actuator of the present invention, the electric motor, the sleeve-like rotor, the speed reduction mechanism, and the nut member are all concentrically housed inside the housing, and the screw shaft disposed at the center thereof is reciprocated. The actuator can be a linear compact form.

The electric actuator of the present invention is provided with a brake mechanism, and automatically applies a braking force to the sleeve-like rotor when the electric motor is de-energized. For this reason, even if the inertia moment of the sleeve-like rotor (the armature of the electric motor) is large, the sleeve-like rotor stops rotating immediately when the electric motor is de-energized, and the screw shaft continues to rotate due to the inertia of the sleeve-like rotor. It is possible to prevent the position of the driven object from shifting.
Since this brake mechanism is installed between the sleeve-like rotor and the speed reduction mechanism and applies a braking force before the transmission torque is increased by the speed reduction mechanism, the braking torque required to stop the sleeve-like rotor is Small ones are fine. In addition, since the brake mechanism can be released manually, in the unlikely event that a failure occurs in the electric motor or the power distribution system, the braking target is released so that the drive object connected to the screw shaft can be broken. Can be manually moved to a position suitable for repair. Alternatively, it is possible to bring a driving object such as a wing into a maintenance shop for repairing in a state that does not hinder the traveling of the vehicle.

  As in the second aspect of the present invention, a non-excitation actuated dry single-plate brake is adopted as the brake mechanism of the electric actuator of the present invention, that is, a brake disk is fixed to a sleeve-like rotor, and a friction plate is attached thereto. If the brake mechanism is configured by a pressing spring that presses and applies a braking force and an excitation coil that separates the friction plate during energization of the electric motor, a highly reliable brake mechanism can be obtained with a simple structure.

The invention of claim 3 is such that a ball is interposed between the rotating nut member and the screw of the reciprocating screw shaft, that is, a so-called ball screw mechanism is employed in a portion that converts the rotational motion into a linear motion. It is. When the ball screw mechanism is used, the transmission efficiency is increased by reducing the friction between the sliding members, so that the electric actuator can be operated smoothly and the power consumption can be reduced.
Here, when the friction is reduced by using the ball screw mechanism, there is a possibility that the sleeve-like rotor of the electric motor is reversely driven by gravity acting on the driven object, but the electric actuator of the present invention. This situation does not occur because the Brake has a brake mechanism.

  In the invention of claim 4, a rotational position detector for detecting the rotational position of the electric motor (sleeve-like rotor), for example, a rotary encoder is installed in the housing, and a motor control device for controlling the electric motor is also installed. It is. When such a rotational position detector is provided to control the electric motor, even if a general DC motor or AC motor is used as the electric motor, the rotational state of the electric motor is adjusted to adjust the position of the driven object. If the object to be driven is a wing, it is possible to easily execute the slow start and stop (slow start, slow stop) control as in Patent Document 1. Furthermore, as in the invention of claim 5, when the motor control device is provided with a synchronous control unit that drives a plurality of actuators synchronously, a total of four electric actuators installed on the upper and lower frames of the wing body Synchronized with each other, it is possible to prevent malfunction such as tilting in the front-rear direction and twisting during opening and closing of the wing.

It is a figure which shows the electric actuator of this invention generally. It is detail drawing which shows the brake mechanism of the electric actuator of FIG. It is detail drawing which shows the deceleration mechanism of the electric actuator of FIG. It is a figure which shows a general wing and its hydraulic actuator for opening and closing. It is a figure which shows an example of the conventional electric actuator.

Hereinafter, the electric actuator of the present invention will be described with reference to the drawings.
As shown in the overall view of FIG. 1, in the electric actuator of the present invention, an electric motor 2 capable of normal rotation and reverse rotation is installed inside a cylindrical housing 1. Although the electric motor 2 is not shown in detail, a rotor (armature) that rotates inside a stator fixed to the housing 1 is arranged like a general DC motor or AC motor. On the inside, a hollow sleeve-like rotor 3 is fixed. A screw shaft 4 extending through the hollow sleeve-like rotor 3 is disposed at the center of the cylindrical housing 1, and a screw formed on the screw shaft 4 is disposed at one end in the axial direction of the housing 1. The placed nut member 5 is fitted.

The nut member 5 is connected to the sleeve-like rotor 3 through the brake mechanism 6 and the speed reduction mechanism 7 and is rotated by the electric motor 2 to linearly move the screw shaft 4. A ball 51 is interposed between the nut member 5 and the screw to form a ball screw mechanism, which reduces friction loss when converting rotational motion into linear motion.
The screw shaft 4 is an output member of the electric actuator. When the driven object is a wing of the wing body, a clevis (connection fitting) 41 at the tip of the screw shaft 4 is coupled to the wing, The opposite clevis 11 fixed to the housing 1 is pivotally attached to the upper part of the rear frame of the wing body. Between the clevis 41 of the screw shaft 4 and the housing 1, a bellows-like rubber tube that expands and contracts may be provided in order to prevent entry of dust and the like. Further, a retaining guide 42 is fixed to the end of the screw shaft 4 opposite to the clevis 41.

In the electric actuator of the present invention, the brake mechanism 6 connected to the sleeve-like rotor 3 of the electric motor 2 is a non-excitation actuated dry single-plate brake in this embodiment. As shown in FIG. 2, the brake mechanism 6 includes a brake disk 61 fixed to the sleeve-like rotor 3 and a brake operating body 62 that houses the brake disk 61. The brake actuating body 62 is a member made of a magnetic material and connecting the outer circumferences of two discs arranged with the brake disc 61 in between, and on the surface of the one disc facing the brake disc 61. Is provided with a friction lining 63, and the disk constitutes a friction plate.
Further, the brake mechanism 6 has a fixing member fixed to the housing 1. The fixing member includes a pressing spring 64 that presses the friction lining 63 of the brake operating body 62 against the brake disc 61, and the brake operating body 62. An exciting coil 65 is attached that attracts magnetic friction and separates the friction lining 63.

  The brake mechanism 6 is provided with a manual release device for manually releasing the brake. The manual release device includes a press ball 66 for pressing the brake operating body 62 in a direction opposite to the press spring 64 and a release screw 67 fitted in the screw hole of the housing 1 for moving the press ball 66. A conical body is formed at the tip of the release screw 67, and the side surface of the conical body is in contact with the pressing ball 66.

Here, the operation of the brake mechanism 6 of the electric actuator of the present invention will be described.
The brake operating body 62 of the brake mechanism 6 is normally pressed by a pressing spring 64, and its friction lining 63 is pressed against the brake disk 61, and a braking force acts on the sleeve-like rotor 3 of the electric motor 2. ing. In this brake mechanism 6, when the electric motor 2 is energized so as to displace a driving object such as a wing, a control circuit is configured so that current is also passed through the exciting coil 65 and excited in conjunction therewith. . Therefore, when the electric motor 2 is energized, the brake actuating body 62 is attracted, the friction lining 63 and the brake disk 61 are separated, and the braking force for the movement of the screw shaft 4 is released. On the other hand, when the electric motor 2 is de-energized, a braking force is immediately applied to the sleeve-like rotor 3 of the electric motor 2 and the screw shaft 4 stops, so that the moment of inertia of the sleeve-like rotor 3 is increased. At most, the position of the driven object can be accurately controlled by energization and interruption of the electric motor 2.

Should a failure occur in the energization system of the electric motor 2 or the exciting coil 65 and the braking force remains applied to the sleeve-like rotor 3, the release screw 67 of the manual release device is moved to the center of the housing 1 with a screwdriver. Screw in toward. As a result, the pressing ball 66 is pushed by the cone at the tip of the release screw 67 and moves to the right in FIG. 2 to move the brake actuating body 62 against the pressing spring 64, and the friction lining 63. And the brake disc 61 are forcibly separated. Since the braking force acting on the sleeve-like rotor 3 disappears, the restraint of the screw shaft 4 is released, and the driven object can be manually moved to a position suitable for repair.
As a manual release device, as shown in the modified example in the lower part of FIG. 2, a pin 66A having a slope formed in place of the pressing ball is inserted into the hole, and a release screw 67A having a cam body attached to the slope of the pin 66A is attached. May be pushed in.

  Since the brake mechanism 6 of the present invention is placed at a position before the rotational speed is reduced by the speed reduction mechanism 7, that is, a position before the rotational torque is increased, the frictional force required for braking the brake disk 61 is small. . Further, since the sleeve-like rotor 3 is applied to a portion having a large diameter at the outer peripheral portion, the frictional force required for braking is small from this point. In the embodiment of FIG. 2, the sleeve-like rotor 3 is extended and a brake disk 61 is formed at the extension, but as shown by a two-dot chain line in the figure, a separate member fixed to the sleeve-like rotor is provided. A brake disc can also be formed on the hollow shaft.

As shown in FIG. 3, in this embodiment, a planetary gear speed reduction device is employed as the speed reduction mechanism 7 of the electric actuator of the present invention.
In the planetary gear speed reduction device of FIG. 3, a hollow sun gear shaft 71 that forms a sun gear SG is flange-coupled to the sleeve-like rotor 3. A ring gear RG that is an internal gear is fixed to the housing 1, and a planetary gear PG that meshes with both gears is disposed between the sun gear SG and the ring gear RG. A support shaft 52 that supports the planetary gear PG is fixed to the nut member 5.

The nut member 5 that supports the planetary gear PG corresponds to a planet carrier in a general planetary gear device, and rotates at the same speed as the revolution of the planetary gear PG. In other words, the speed reduction mechanism 7 is a speed reduction device having the sun gear shaft 71 as an input shaft and the nut member 5 (support shaft 52) whose rotation center axis is coaxial with the output shaft as an output shaft. As is known, it is expressed by the following equation.
Reduction ratio: 1 / (1+ (ZRG / ZSG))
ZSG: Number of teeth of sun gear, ZRG: Number of teeth of ring gear Thus, in the electric actuator of this embodiment, the rotational speed of the electric motor 2 is reduced according to the reduction ratio described above, and the nut member 5 is rotated. The sleeve-like rotor 3, the speed reduction mechanism 7 and the nut member 5 are all housed concentrically inside the housing 1 and reciprocate the screw shaft 4 disposed at the center thereof. As a compact form, the mountability on a vehicle can be improved.

With reference to FIG. 1 again, the outline of the control device in the electric actuator of the present invention will be described.
Inside the housing 1 of the electric actuator, a rotary encoder 8 for detecting the rotational position of the sleeve-like rotor 3 is installed on the opposite side of the electric motor 2 from the brake mechanism 6 and the like. A motor control device 9 for controlling is also installed. When the rotary encoder 8 which is a rotational position detector is provided and the chopper control of the energization current of the electric motor 2 and the inverter control of the frequency are performed, even if a general DC motor or AC motor is used, The speed can be easily controlled. When the object to be driven is a wing, slow start and slow stop control can be easily executed to prevent rainwater from being caught at the start of opening and impact at the time of closing.

If the object to be driven by the electric actuator is a wing, the control device 9 is provided with a synchronization control unit that drives a plurality of actuators in synchronization. For example, the synchronization control unit is configured to compare the rotation amounts of the electric motors in the two electric actuators, and to perform correction to increase the energization amount of the actuator having the smaller rotation amount. By synchronizing the electric actuators installed on the upper and lower frames of the body, it is possible to prevent malfunctions such as torsion during opening and closing of the wing.
When a pulse motor is used as the electric motor and the rotation angle is in accordance with the number of generated pulses, a rotation number detector such as a rotary encoder is not necessary. When a servo motor is used, the rotational position of one electric motor can be made to follow the rotational position of the electric motor in another actuator.

  As described in detail above, the electric actuator for a vehicle according to the present invention is provided with a hollow rotor through which a screw shaft penetrates an electric motor, and a brake mechanism with a manual release device and a speed reduction mechanism for rotating a nut member are coaxial. It is arranged in a shape. In the above-described embodiments, the case where the electric actuator is used as a wing drive device has been described, but it goes without saying that the vehicle electric actuator of the present invention can be applied to a movable part such as a tailgate lifting device. Yes. Also, instead of the dry single plate brake that is the brake mechanism of the embodiment, instead of the planetary gear device that is a reduction mechanism that employs a brake of a type in which a brake shoe is pressed against the circumferential surface of the sleeve-like rotor, on both sides It is clear that various modifications can be made to the above-described embodiment, such as using a so-called harmonic type (harmonic is a registered trademark) speed reducer by installing an elastic ring in which tooth forms with different numbers of teeth are formed. .

DESCRIPTION OF SYMBOLS 1 Housing 2 Electric motor 3 Sleeve-like rotor 4 Screw shaft 5 Nut member 6 Brake mechanism 61 Disc for brake 63 Friction lining 65 Excitation coil 67 Release screw (for manual release)
7 Deceleration mechanism 8 Rotary encoder

Claims (5)

An electric actuator in which a screw shaft formed with a screw and a nut member fitted to the screw are installed, and the screw shaft is reciprocated by rotating the nut member by an electric motor capable of normal / reverse rotation fixed to a housing Because
The electric actuator is installed in a vehicle,
The electric motor includes a hollow sleeve-like rotor through which the screw shaft passes, and the sleeve-like rotor is connected to the nut member via a speed reduction mechanism in which the rotation center axis of the input / output shaft is coaxial. And
A brake mechanism is provided between the sleeve-like rotor and the speed reduction mechanism to automatically apply a braking force when the electric motor is de-energized. The brake mechanism can be released manually. The electric actuator characterized by being. The brake mechanism is a non-excitation actuated dry single-plate brake, a brake disk fixed to the sleeve-like rotor, and a pressing spring that presses a friction plate against the brake disk to apply a braking force. The electric actuator according to claim 1, further comprising an exciting coil that separates the brake disk and the friction plate during energization of the electric motor. The electric actuator according to claim 1, wherein a ball is interposed between the nut member and a screw formed on the screw shaft. The rotation position detector which detects the rotation position of the said electric motor is installed in the said housing, The motor control apparatus which controls the said electric motor is installed in any one of Claims 1 thru | or 3. Electric actuator. The electric actuator is an actuator for opening and closing a wing body mounted on a vehicle, and the motor control device that controls the electric motor is provided with a synchronous control unit that drives a plurality of actuators synchronously. 4. The electric actuator according to 4.

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