JPH02273050A - Electrically-driven actuator - Google Patents

Abstract

PURPOSE:To output a force enough to effect a predetermined work by other electric motors even when one set of electric motor becomes faulty by a method wherein a plurality of electric motors is provided and the outputs of respective electric motors are set so small that the total output of them becomes a necessary output. CONSTITUTION:A screw shaft is employed as an input member 2 and a nut is employed as an output member 6 while two sets of electric motors 3 are provided and the outputs of respective electric motors 3 are set so as to be one half of the total output so that the total output becomes a necessary output. When either one of the electric motors 3 becomes faulty, only one set of the electric motor 3 is operated and the output thereof becomes one half of the necessary output whereby a work is delayed, however, a torque for rotating the screw shaft 4 is outputted. Accordingly, a force, enough to effect a predetermined work, maybe outputted by the other electric motor 3 even when one set of the electric motor 3 becomes faulty whereby the work may be done without any trouble.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electric actuator, and in particular, it is possible to provide a plurality of electric motors so that the output of each electric motor can be small, and to prevent Even in the event of a failure, other electric motors operate to reduce the operating speed while allowing the output member to perform the specified work, resulting in high safety (for example, suitable for shifting and selecting operations in automatic transmissions in vehicles). related to electric actuators.

Conventional technology Conventionally, manual gear-type transmissions have been improved without using torque converters, and this has been automated using actuators using computers and fluid pressure cylinders, allowing the driver to shift gears with just a light finger touch. So, a shift that requires force,
Automatic transmissions are in practical use in which the selection operation is performed by an actuator using a fluid pressure cylinder.

However, fluid pressure cylinders are characteristically "constant torque type," so the "force" that does work is determined by the product of fluid pressure and the effective pressure-receiving area of the piston in the cylinder. However, there was a problem in that it was difficult to control the output. Furthermore, in conventional automatic transmissions of this type, only one fluid pressure cylinder is used for shift and selection operations, so if one of the fluid pressure cylinders breaks down, However, it was predicted that the receiver's work would stop and the shift or select operation would become impossible, so there was room for improvement.

Therefore, in order to eliminate this drawback, it is possible to configure one actuator with multiple fluid pressure cylinders and set the output of each fluid pressure cylinder to be small so that the total output becomes the required output of the actuator. As mentioned above, the characteristics of fluid pressure cylinders are "constant torque type", so if one fluid pressure cylinder fails, if you try to make work only with the other fluid pressure cylinder, it will not work. The "force" required to shift does not increase even if the speed is reduced. Therefore, for example, if there are two fluid pressure cylinders, this "force" will be 1/2 of the necessary "force", and the shift Or, the result is that the select operation cannot be performed,
The drawback was that it was not practical.

On the other hand, in electric actuators that use an electric motor, the characteristics of the electric motor are "constant output type", so if one electric motor fails, only the other electric motor is required. If you try to get the work done,
Although the speed is reduced, it can generate enough "power" to do the work, so even if the electric motor has only 1/2 of the required output, it can be used to perform a shift or select operation. However, there is no conventional electric actuator that uses multiple electric motors to form a single actuator. For example, JP-A-61-18
The electric actuator disclosed in No. 1153 has only one electric motor attached to one actuator, so if this one electric motor breaks down, it cannot be used at all. there were.

Purpose The present invention was made in order to eliminate the drawbacks of the prior art described above, and its purpose is to take advantage of the "constant output type" characteristics of electric motors and to use a plurality of electric motors. By configuring one electric actuator, even if one electric motor breaks down, the other electric motors will output the specified "power to do the work" and the necessary work will be performed without any problems. It is to be. Another purpose is to make it possible to use small electric motors by setting the output of each electric motor small so that the total output of multiple electric motors is the required output, thereby reducing the size and weight of the device. The aim is to reduce costs. In addition, other purposes are
The purpose of this invention is to simplify the structure of the device and reduce costs by using screw devices for the input and output members. Still another object is to accurately grasp the progress state of a shift select operation of an automatic transmission, for example, by providing a position sensor that detects the relative position of an output member with respect to a reference position in addition to an electric motor, and to detect information from the position sensor. The purpose is to input detection signals into a computer to enable fine control. Another purpose is to shorten the length of the electric actuator by arranging an electric motor in parallel on one side of the screw shaft serving as the input member, thereby making the device more compact in terms of length. . Another purpose is to reduce the thickness of the electric motor part by arranging the electric motor in series with a common rotation axis on one side of the screw shaft serving as the input member, thereby making the device more compact in terms of thickness. The goal is to make the world a better place. Still another object is to reduce mechanical loss due to sliding friction and improve mechanical efficiency by using a gear device consisting of a worm and a worm wheel for the input and output members.

Configuration In short, the present invention (claim 1) provides an electric actuator in which an input member is driven by an electric motor,
The present invention is characterized in that a plurality of the electric motors are provided, and the output of each electric motor is set small so that the total output of the plurality of electric motors is the required output.

Further, the present invention (claim 2) provides a screw device comprising a screw shaft and a nut screwed onto the screw shaft, wherein one of the screw shaft and the nut is an input member and the other is an output member. In an electric actuator that is driven by an electric motor, a plurality of the electric motors are provided, and the output of each electric motor is set to a small value so that the total output of the plurality of electric motors becomes the required output. It is characterized by this.

Further, the present invention (claim 3) provides a screw device comprising a screw shaft and a nut screwed onto the screw shaft, wherein one of the screw shaft and the nut is an input member and the other is an output member. In an electric actuator that is driven by an electric morph, a plurality of the electric motors are provided, and the output of each electric motor is set small so that the total output of the plurality of electric motors is the required output, and the The present invention is characterized in that it includes a position sensor that detects the relative position of the output member with respect to a reference position.

Further, the present invention (claim 4) provides a screw device comprising a screw shaft and a nut screwed onto the screw shaft, wherein either one of the screw shaft or the nut is an input member and the other is an output member. In the electric actuator, the electric motor is driven by an electric motor, and two electric motors are provided, and the two electric motors are provided.
This is characterized in that the output of each electric motor is set to be 1/2 of the total output so that the total output of the three electric motors becomes the required output.

Further, the present invention (claim 7) provides a gear device including a worm and a worm wheel that meshes with the worm, with the rotating shaft of the worm being an input member, and the worm wheel being an output member, and the input member being driven by an electric motor. A plurality of the electric motors are provided, and the output of each electric motor is set to be small so that the total output of the plurality of electric motors is the required output. .

Further, the present invention (claim 8) provides a gear device including a worm and a worm wheel that meshes with the worm, with the rotating shaft of the worm being an input member, and the worm wheel being an output member, and the input member being driven by an electric motor. A plurality of electric motors are provided, and the output of each electric motor is set small so that the total output of the plurality of electric motors is the required output, and the output member is configured to be driven relative to a reference position. This device is characterized by being equipped with a position sensor that detects the position.

The present invention will be explained below based on embodiments shown in the drawings. As shown in FIGS. 1 to 6, an electric actuator 1 according to the present invention is an electric actuator in which an input member 2 is driven by an electric motor 3, and a plurality of electric motors 3 are provided. The output P of each electric motor 3 is set small so that the total output PT of the electric motors 3 becomes the required output PD (PT=PD). Therefore,
When the number of electric motors 3 is n, the output P of each electric motor 3 is P = P T / n = P D / n
It is set so that Each electric motor 3 is configured so that current is supplied to all of them to rotate while the electric actuator l is in operation, and if one of them breaks down, the other electric motors 3 continue to rotate. , P.sub.D/n, which is a small output P, is configured to be able to reduce the operating speed of the electric actuator 1 while still performing operations such as transmission shifting and selection operations.

Next, a first embodiment (claims 1 to 5) of the electric actuator 1 according to the present invention will be described with reference to FIGS. 1 and 2. The electric actuator 1 includes a screw shaft 4,
One of the screw devices S consisting of a nut 5 screwed onto the screw shaft is used as an input member 2, and the other is used as an output member 6, which is driven by an electric motor 3. In the embodiment, the screw shaft 4 is used as the input member 2, the nut 5 is used as the output member 6, and the electric motor 3 is used as the input member 2.
The output P of each electric motor 3 is set to be 1/2 of the total output PT so that the total output PT of the two electric motors 3 becomes the required output PD. It also includes a position sensor 8 that detects the relative position of the output member 6 with respect to the reference position.

The position sensor 8 employs a dual potentiometer in the illustrated embodiment.

The two electric motors 3 are fixed to a machine frame 9, and their rotating shafts 3a are rotatably supported by the machine frame 9 via bearings 10, and are mounted inside a gear chamber 9a provided in the machine frame 9. A driving gear 11 is fixed to one end of the protruding part. That is, in this embodiment, the electric motor 3 is arranged in parallel on one side of the screw shaft 4 and is configured to drive the screw shaft 4 via the gear mechanism G. The driving gear 11 meshes with a driven gear 13 fixed to a screw shaft 4 rotatably supported on the machine frame 9 via a bearing 12. The nut 5 is screwed onto the screw shaft 4, and has a rectangular cross section so as not to rotate.A pair of pins 14 protrude horizontally from the center of the nut 5, and the pin is one of the output members 6. The nut 5 engages with a groove 15a formed at the lower end of a two-pronged crank 15 fixed to one end of a shift select shaft 16 forming a part of the shift select shaft 16, and the nut 5 is slidably fitted into the two-pronged crank 15. There is. The position sensor 8 is fixed to the machine frame 9, and one end of a crank 18 connected to the nut 5 is fixed to its rotating shaft 8a so as to swing in conjunction with the movement of the nut 5.

Next, a second embodiment (claim 6) of the electric actuator 1 according to the present invention will be described with reference to FIGS. 3 and 4. Note that the same parts as in the first embodiment are designated by the same reference numerals in the drawings, and their explanations will be omitted. Similarly, two electric motors 3 are provided, and are arranged in series with a screw shaft 4 as an input member, with the rotation shaft 3a in common on one side of the screw shaft, and the screw shaft is connected to the screw shaft via a gear mechanism G. configured to drive. Inside the electric motor 3, the rotating shaft 3
A rotor 3b of each electric motor 3 is fixed to a, a field coil 3c is provided around the rotor 3b, and a rotating shaft 3a is rotatably supported by a bearing 3d.

The gear mechanism G employs a planetary gear mechanism, unlike the first embodiment. That is, a driving gear 11 is fixed to the rotating shaft 3a of the electric motor 3, and the driving gear meshes with a pair of driven gears 19, which are planetary gears.
It is rotatably attached to the arm member by a pair of pivots 21 implanted in the arm member. The arm member 20 is fixed to one end 4a of the screw shaft 4, and the driven gear 19 meshes with an internal gear 22 fixed to the machine frame 9. A worm 4C is formed on the other end 4b of the screw shaft 4, and a worm wheel 23 fixed to the rotating shaft 8a of the position sensor 8 meshes with the worm.

Next, a third embodiment (claims 8 and 9) of the electric actuator 1 according to the present invention will be described with reference to FIGS. 5 and 6. The electric actuator 1 uses the rotation shaft 26 of the worm of a gear device G, which is composed of a worm 24 and a worm wheel 25 meshing with the worm, as the input member 2, and uses the worm wheel as the output member 6, and the input member 2 as the input member 2. Two electric motors 3 are provided, and the output of each electric motor 3 is set to PT/PT so that the total output PT of the two electric motors 3 becomes the required output PD. 2, and is provided with a position sensor 8 that detects the relative position of the output member 6 with respect to the reference position.

The electric motor 3 is fixed to the machine frame 9, and its rotating shaft 3a is connected to both sides of a rotating shaft 26, and the rotating shafts are rotatably supported by the machine frame 9 via bearings 28, respectively. . The worm wheel 25 is a sector gear, and is fixed to the shift select shaft 16 rotatably supported by the machine frame 9.

A position sensor 8, that is, a double potentiometer is attached to the shift select shaft.

Function The present invention is constructed as described above, and its function will be explained below. First, the operation of the electric actuator 1 according to the first embodiment shown in FIGS. 1 and 2 will be explained. When the electric actuator 1 is used, for example, for shifting or selecting a transmission, When a command unit (not shown) having a change lever installed in the driver's seat of the vehicle is operated and a command signal for shift or selection is sent to a control device (not shown), the electric motor 3 A current is supplied to the electric motor, the electric motor rotates, the driving gear 11 rotates the driven gear 13, and the total output PT of the two electric motors 3 is transmitted to the screw shaft 4, which is the input member 2. The screw shaft rotates, and the nut 5, which is the output member 6, reciprocates left and right in the figure as shown by arrows A and B depending on the direction of rotation of the screw shaft 4. As a result, the pin 14 moves into the forked groove 15a of the crank 15. The shift select shaft 16 swings as shown by arrows C and D. As a result, the automatic transmission is shifted or selected as appropriate.In this case, the two electric motors 3 is operating normally, the total output PT is the electric actuator 1.
Since it is equal to the required output PD of the electric actuator 1
operates at normal speed and shifts or select operations are performed smoothly.

Therefore, to explain the case where either one of the electric motors 3 breaks down, in this case, only one electric motor 3 will operate, so its total output PT will be 1/2 of the required output PD. It ends up. However, the electric motor 3
Due to its "constant output type" characteristics, its working speed is slow (
If so, it will be possible to generate the "force" or torque necessary to rotate the screw shaft 4. Therefore, the time required for the shift operation is approximately twice as long as in the normal case, and although the work speed is reduced, the shift or selection operation is completed completely.

Further, the progress of the shift or select operation is sequentially read by the position sensor 8 as the rotary shaft 8a of the position sensor 8 swings as shown by the imaginary line via the crank 18 due to the reciprocating movement of the nut 5. A signal from the position sensor is input to the control device, and when the shift or select operation is completed, a signal is sent from the control device to stop supplying current to the electric motor 3, and the electric motor 3 is stopped.

Next, the operation of the electric actuator 1 according to the second embodiment shown in FIGS. 3 and 4 will be explained. In this embodiment, the gear device G employs a planetary gear device, and the screw shaft The only difference from the first embodiment is that power is transmitted from the position sensor 4 to the position sensor 8 by a worm gear device, and the other configurations are the same as the first embodiment.
A detailed explanation of the functions of similar parts will be omitted. Since the electric motors 3 have a common rotation axis 3a, the total output PT of the two electric motors 3 is equal to the required output PD of the electric actuator 1, and under normal conditions, the shift or select operation is performed at the normal speed. will be held. and drive gear 1
1 causes a pair of driven gears 19 to rotate, thereby causing the pair of driven gears to move relative to the internal gear 22, and as a result, the arm member 20 rotates and the rotation is caused by the rotation of the screw shaft 4.
The nut 5 reciprocates as shown by arrows A and B.

Similarly, a shift or select operation is performed. Furthermore, if one of the electric motors 3 fails, its rotation will stop, but the other electric motor 3 will rotate and the first
As in the embodiment, the shift operation is performed perfectly even though the working speed is reduced.

Finally, to explain the operation of the electric actuator 1 according to the third embodiment shown in FIGS. 5 and 6, the rotation of the electric motor 3 rotates the worm 24, which rotates the worm wheel 25, and selects the shift select. The shaft 16 swings and a shift or selection operation is performed, but
Similarly, even if one electric motor 3 breaks down, the other electric motor 3 will rotate at a reduced speed.
A shift operation will be performed.

As described above, if the electric actuator 1 according to the present invention is used for shift selection operation of an automatic transmission of a vehicle, unlike a conventional fluid pressure cylinder having a "constant torque type" characteristic, the electric actuator 1 according to the present invention has a "constant output type" characteristic. By taking advantage of its characteristics and slowing down its operating speed, it is possible to have the single non-faulty electric motor 3 perform the shifting operation, so even in the unlikely event of an emergency, the vehicle can be driven while shifting the transmission. can be done.

Effects As described above, the present invention takes advantage of the "constant output type" characteristic of electric motors and configures one electric actuator using multiple electric motors, so even if one electric motor breaks down, This also has the effect of allowing the other electric motors to output a predetermined "power to do work" so that necessary work can be performed without any hindrance. In addition, since the output of each electric motor is set small so that the total output of multiple electric motors is the required output, it is possible to use small electric motors.
This has the effect of reducing the size, weight, and cost of the device. Further, since screw devices are used for the input member and the output member, it is possible to simplify the structure of the device and reduce costs. Furthermore, in addition to the electric motor, it is equipped with a position sensor that detects the relative position of the output member with respect to the reference position, so it is possible to accurately grasp the progress status of, for example, a shift select operation of an automatic transmission, and the detection signal from the position sensor can be transmitted to a computer. This has the effect of allowing fine-grained control to be performed by inputting information. Furthermore, since the electric motor is arranged in parallel on one side of the screw shaft serving as the input member, the length of the electric actuator can be shortened, thereby making it possible to make the device more compact in terms of length. In addition, since the electric motors are arranged in series with a common rotation axis on one side of the screw shaft serving as the input member, the thickness of the electric motor portion can be reduced, and the device can be made more compact in terms of thickness. There is an effect that can be done. Furthermore, since a gear system consisting of a worm and a worm wheel is used for the input and output members, mechanical loss due to sliding friction is reduced (
This has the effect of improving machine efficiency.

[Brief explanation of drawings]

1 and 2 relate to the first embodiment of the present invention, FIG. 1 is a longitudinal sectional view of an electric actuator, FIG. 2 is a perspective view of the main part, and FIGS. 3 and 4 are Regarding the second embodiment, FIG. 3 is a vertical sectional view of the electric actuator, FIG. 4 is a perspective view of the main part, and FIGS. 5 and 6 are related to the third embodiment of the present invention, and FIG. A vertical cross-sectional view of the electric actuator, FIG. 6 is a right side view of the one shown in FIG. 5. 1 is an electric actuator, 2 is an input member, 3 is an electric motor, 4 is a screw shaft, 5 is a nut, 6 is an output member, 8 is a position sensor, 24 is a worm, 25 is a worm wheel,
26 is a rotating shaft, G is a gear device, and S is a screw device. Patent applicant Hino Motors Co., Ltd.

Claims (1)

[Scope of Claims] 1. In an electric actuator in which an input member is driven by an electric motor, a plurality of the electric motors are provided, and each electric motor is controlled so that the total output of the plurality of electric motors becomes the required output. An electric actuator characterized by having a small output. 2. A screw device consisting of a screw shaft and a nut screwed onto the screw shaft, in which one of the screw shaft and the nut is an input member, the other is an output member, and the input member is driven by an electric motor. An electric actuator characterized in that a plurality of the electric motors are provided, and the output of each electric motor is set small so that the total output of the plurality of electric motors is the required output. 3. A screw device consisting of a screw shaft and a nut screwed onto the screw shaft, in which one of the screw shaft and the nut is an input member, the other is an output member, and the input member is driven by an electric motor. In the electric actuator, a plurality of the electric motors are provided, the output of each electric motor is set small so that the total output of the plurality of electric motors is the required output, and the relative position of the output member with respect to the reference position is set. An electric actuator characterized by being equipped with a position sensor for detection. 4. A screw device consisting of a screw shaft and a nut screwed onto the screw shaft, with one of the screw shaft and the nut being an input member and the other being an output member, and the input member being driven by an electric motor. In the electric actuator, two electric motors are provided, and the output of each electric motor is set to be 1/2 of the total output so that the total output of the two electric motors is the required output. An electric actuator characterized by: 5. The electric motor according to claim 2, wherein the electric motor is arranged in parallel on one side of the screw shaft using the screw shaft as an input member, and is configured to drive the screw shaft via a gear mechanism. The electric actuator according to any one of the items. 6. The electric motors are arranged in series with the screw shaft as an input member on one side of the screw shaft with a common rotation axis, and are configured to drive the screw shaft via a gear mechanism. The electric actuator according to any one of claims 2 to 4. 7 A gear device consisting of a worm and a worm wheel meshing with the worm is configured such that the rotating shaft of the worm is an input member, the worm wheel is an output member, and the input member is driven by an electric motor, An electric actuator characterized in that a plurality of motors are provided, and the output of each electric motor is set small so that the total output of the plurality of electric motors is the required output. 8 A gear device consisting of a worm and a worm wheel meshing with the worm is configured such that the rotation shaft of the worm is used as an input member, the worm wheel is used as an output member, and the input member is driven by an electric motor, A plurality of motors are provided, and the output of each electric motor is set small so that the total output of the plurality of electric motors is the required output,
An electric actuator further comprising a position sensor that detects a relative position of the output member with respect to a reference position. 9. The electric actuator according to claim 3 or 8, wherein the position sensor is a potentiometer.