(12) PUBLICATION OF PATENT APPLICATION (A)
`(19) Japan Patent Office (JP) (11) Patent Application Publication No.
`H6-335228
`December 2, 1994 (Heisei 6)
`(43) Publication Date
`(51) Int. Cl.5 Identification Code Internal Ref. No. FI Technology Indication Section
` H02K 37/24 Q 9180-5H
` B60Q 1/06
` H02K 11/00 C
` 37/14 535 Y 9180-5H
`8715-3K B60Q 1/06 A
`Examination Request: Not Made Number of Claims: 3 FD (Total 5 pages)
`(71) Applicant
`000114215
`(21) Application No. H5-139092
` Minebea Co., Ltd.
`
`4106-73, Oaza-Miyota,
`(22) Filing Date May 17, 1993 (Heisei 5)
`Miyota-machi, Kitasaku-gun,
`Nagano-ken
`Yuzuru Suzuki
`c/o R&D Center,
`Minebea Co., Ltd.,
`1743-1, Asana, Asaba-cho,
`Iwata-gun, Shizuoka-ken
`Sakae Fujitani
`c/o R&D Center,
`Minebea Co., Ltd.,
`1743-1, Asana, Asaba-cho,
`Iwata-gun, Shizuoka-ken
` Minoru Tsuji, Patent Attorney
`
`Continued on Last Page
`
`
`
`1
`
`(72) Inventor
`
`(72) Inventor
`
`(74) Agent
`
`
`5
`
`10
`
`
`
`1
`
`SL-1016
`
`

`
`
`
`
`
`
`(54) [Title of the Invention]
`LINEAR ACTUATOR
`(57) [ABSTRACT]
`[Object] To provide a linear actuator that can
`mount a position detector of an actuator
`therein and has a reliable mechanical stopper.
`[Configuration] An actuator is provided at a
`center of a rotor of an electric motor, the
`actuator being screwed into a screw portion
`provided at the center of the rotor, and when
`a motor composed of a stator and the rotor is
`driven, the rotor starts to rotate. When the
`rotor rotates, the actuator that is screwed
`therein starts an up-down motion, and when a
`position indicator provided on the actuator,
`passes across an opposing portion of a
`position indicator detecting portion provided
`inside a case, an electric position of the
`actuator is confirmed. When the actuator
`goes out of control and is about to deviate
`from a predetermined range, the movement
`of the actuator is restricted by a stopper.
`The point of action of
`the stopper
`is
`adjustable.
`
`
`2
`
`

`
`[CLAIMS]
`[Claim 1] A linear actuator which converts rotational force of a motor into a linear direction
`of an actuator, characterized in that the linear actuator comprises a stator forming a motor, a
`rotor supported rotatably at a center of the stator, an actuator that is screwed into a screw
`provided around a rotation center line of the rotor and is movable along the rotation center
`line by rotation of the rotor, a position indicator that is provided on the actuator and indicates
`a position of the actuator, a position indicator detecting portion that is located inside a case on
`the same stationary side as the stator and detects the position indicator, and a stopper that is
`located outside an moving range of the actuator and by which a mechanical end position of
`the actuator is adjustable.
`[Claim 2] The linear actuator as set forth in claim 1, characterized in that the motor is a
`stepping motor.
`[Claim 3] The linear actuator as set forth in claim 1 or claim 2, characterized in that the
`position indicator is a plastic magnet, and the position indicator detecting portion is a
`magnetic detecting device.
`[DETAILED DESCRIPTION OF INVENTION]
`[0001]
`[Field of Industrial Application] This invention relates to a linear actuator, and in particular,
`relates to a linear actuator that is used for an optical axis adjustment of a headlight of a
`vehicle, more specifically, for an adjustment of an optical axis associated with a change of
`levelness of a vehicle, or for achieving a currently used short/long distance switching by
`changing an inclination of an optical axis with a single lamp.
`[0002]
`[Conventional Art] For automatic in-and-out operations of vehicle headlights or operations of
`office automation equipments, actuators using a motor as a drive source and having a linearly
`moving drive body are used. These actuators include linear actuators that convert rotational
`force of a motor into a linear movement. Such linear actuators include a linear motor type
`in which, on a stator of an electric motor expanded in a shape of a plate, a movable element
`also formed in a shape of a plate is moved, but normally, rotational force of a motor is
`converted into a linear movement using a gear mechanism to drive the actuator in the linear
`direction. In case of using this type of linear actuator for the headlight optical axis direction
`adjustment described above for example, if it is possible to accurately find out a position
`within a stroke range of the actuator moving in the linear direction, it is possible to set an
`optical axis to a desired direction. Further, by detecting only an uppermost position or a
`lowermost end position of the actuator, it is possible to eliminate the need of a mechanical
`stopper with regard to the headlight optical axis position setting. In the past, in order to find
`out a position of the actuator, a position detector is provided outside a case of the linear
`actuator, and therefore, fine positional adjustment between the position detector and the
`actuator is required at the time of assembling. Also, there is a drawback that a configuration
`becomes large in size. In addition, a conventional linear actuator does not have a reliable
`mechanical stopper.
`[0003]
`[Problem to be Solved by Invention] The present invention is to eliminate conventional
`drawbacks described above, and it is an object thereof to provide a linear actuator that can
`mount an actuator position detector therein and has a reliable mechanical stopper.
`[0004]
`[Means for Solving the Problem] In order to achieve the object of the present invention
`described above, this invention provides a linear actuator which converts rotational force of a
`motor into a linear direction of an actuator, characterized in that the linear actuator comprises
`a stator forming a motor, a rotor supported rotatably at a center of the stator, an actuator that
`3
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`

`
`is screwed into a screw provided around a rotation center line of the rotor and is movable
`along the rotation center line by rotation of the rotor, a position indicator that is provided on
`the actuator and indicates a position of the actuator, a position indicator detecting portion that
`is located inside a case on the same stationary side as the stator and detects the position
`indicator, and a stopper that is located outside an moving range of the actuator and by which
`a mechanical end position of the actuator is adjustable.
`[0005]
`[Operation] When a motor composed of a stator and a rotor is driven, the rotor starts to rotate.
`When the rotor rotates, an actuator that is screwed therein starts an up-down motion, and
`when a position indicator provided on the actuator passes across an opposing portion of a
`position indicator detecting portion provided inside a case, an electric position of the actuator
`is confirmed. When the actuator goes out of control and is about to deviate from a
`predetermined range, the movement of the actuator is restricted by the stopper. The point of
`action of the stopper is adjustable.
`[0006]
`[Embodiment] Next, an embodiment of the present invention will be described using the
`drawings. Fig. 1 is a cross-sectional view of the embodiment of this invention, and in the
`same figure, 1 denotes an actuator. The actuator 1 is made of non-magnetic metal, and is
`arranged, so as to be movable in and out in up-down directions, in a case 2 having a
`projecting type cross section and made of non-magnetic material in the same manner. A
`bearing portion 3 of the actuator 1 is axially supported in the form of spline in the upper and
`lower direction, in the vicinity of an inside of a neck portion 4 of the case 2. Fig. 2 is a
`cross-sectional view cut along an A-A line of Fig. 1. As you can understand from Fig. 2, as
`for the bearing portion 3 of the actuator 1, three lines of protrusions 3’ are provided in a
`longitudinal direction of the actuator 1, and inside the neck portion 4, three lines of grooves
`4’ are provided in a longitudinal direction, so that the protrusions 3 are fitted into the grooves
`4’ in a slidable manner. For this reason, the actuator 1 is movable in the longitudinal
`direction, but is not rotatable. On an outer periphery of a lower end portion of the actuator 1,
`a screw 6 is threaded. Inside the case 2, a cylindrical rotor 9 is axially supported in a
`rotatable manner, by bearings 7, 8. On an inner surface of the rotor 9, a screw 10, which
`mesh with the screw 6 threaded in the actuator 1, is threaded. In addition, to an outer
`periphery of the rotor 9, two pieces of ring shaped permanent magnets 11 and 12 are attached
`as a rotor magnet. Stator coils 13 and 14 including magnetic poles are provided through a
`little gap, locating on an outer periphery of the rotor magnet 11 and the rotor magnet 12.
`Meanwhile, by these rotor magnets 11, 12 and the stator coils 13, 14, a widely known PM
`type stepping motor is configured.
`[0007] To a lower part of the case 2, a mounting base plate 15 is attached by screw-in. On a
`lower end of the actuator 1, a stopper 16 for positioning of the actuator 1 is arranged. The
`stopper 16 is screwed in a center part of the mounting base plate 15. As for the stopper 16,
`as shown in Fig. 3, a setter 18 having a point stopper 17 at a tip point thereof is provided at a
`central upper part, a fitting groove 19 of a screw driver is provided on a lower part, and a
`screw part 20 for being screwed in the mounting base plate 15 is provided on an outer
`periphery. Meanwhile, a diameter R of this screw 20 is larger than a diameter of the screw
`10 provided inside the rotor 9. 21 denotes a cover fitted in a bottom surface of the mounting
`base plate 15, which protects the stopper 16. As shown in Fig. 1, Fig. 4 and Fig. 5, at an
`inner side of a shoulder portion 2’ of the case 2, a position detecting device 23 using a HALL
`device that detects magnetism is fitted therein. This position detecting device 23 serves as a
`position indicator detecting portion. A conductive wire is pulled out from the position
`detecting device 23, and is connected to a terminal 24. A cut is formed in the protrusion 3’
`of the actuator 3, and furthermore, a hole communicating with this cut is drilled in the
`4
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`

`
`actuator 3, so that a plastic magnet 25 for position indicator is fitted in these cut and hole.
`[0008] Next, an operation of the above-described embodiment is explained. When
`predetermined pulses for driving are applied to the stator coils 13 and 14 from a stepping
`motor driving circuit provided separately, the rotor 9 starts to rotate. By the rotation of the
`rotor 9, the actuator 1, which is screwed into the rotor 9, moves in the upper and lower
`direction in Fig. 1. A tip point of the actuator 1 is connected to a base to which a headlight
`of a vehicle has been attached. Then, if the actuator 1 starts to move in the front-rear (A)
`direction shown in Fig. 6, an optical axis of a headlight is changed by  degree. In addition,
`if rotation of the rotor 9 is stopped in the mid-course of the movement of the actuator 1, the
`actuator 1 stops at that position, so that it is possible to fix a light radiation direction of the
`headlight in a desired direction.
`[0009] When the actuator 1 continues to move down, the cover covering the headlight is
`closed. Then, the plastic magnet 25 passes in front of the position detecting device 23, and
`the position detecting device 23 detects magnetism of the plastic magnet 25, so that a current
`position of the actuator 1 is detected. Although the drawings do not show, a driving circuit
`of a pulse motor receives this signal. For example, it detects that the actuator 1 arrives at an
`electric end position, to give an instruction to stop rotation of the pulse motor or the like.
`[00010] When the driving circuit of the pulse motor goes out of order at this time and there
`occurs a situation that rotation of the pulse motor does not stop, a bottom 22 of the actuator 1
`is brought into contact with the point stopper 17 of the stopper 16. At this time, the actuator
`1 stops moving further downwards by this means. In addition to the diameter R of the screw
`of the stopper 16 being larger than a diameter of the screw of the actuator 1, a tip of the point
`stopper 17 is of a point touch. Therefore, rotational force of the actuator 1 is not transmitted
`to the stopper 16, so that a situation that the screw of the stopper 16 slackens by contact of the
`actuator 1 and drops out from the mounting base plate 15 does not occur. Then, the driving
`circuit of the stepping motor supplies a pulse of a certain period of time (desired pulses + 
`pulse) to the stepping motor and stops it after that, to stop rotation of the stepping motor.
`[0011] In addition, when a position where the point stopper 17 and the bottom 22 of the
`actuator 1 are brought into contact with each other is changed by fitting a screw driver in the
`fitting groove 19 provided in the bottom of the stopper 16 and rotating the screw driver
`stopper 16, it is possible to change a mechanical lowermost end position of the actuator 1.
`[0012]
`[Effect of Invention] As described above in detail, according to the present invention, with
`the linear actuator that converts rotational force of the motor in a linear direction of the
`actuator, the position indicator is provided on the actuator and the position indicator detecting
`portion is provided inside the case that supports the movement of the actuator, and therefore,
`as compared with conventional ones in which a position indicator detecting portion is
`provided outside the linear actuator, it has many advantages - not only it is possible to form a
`compact configuration, but also possible to eliminate the need to align the position indicator
`and the position indicator detecting portion when assembling, and furthermore, even if the
`motor goes out of control, unnecessary overrun of the actuator does not occur since the
`mechanical stopper is provided.
`[Brief Description of the Drawings]
`[Fig. 1] a partial cross-sectional view of an embodiment of a linear actuator according to the
`present invention.
`[Fig. 2] a cross-sectional view taken along the line A-A of Fig. 1.
`[Fig. 3] a cross-sectional view of a stopper 16.
`[Fig. 4] a partial perspective view of the actuator.
`[Fig. 5] a cross-sectional view showing a positional relationship between a position indicator
`and a position indicator detecting portion.
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`5
`
`

`
`[Fig. 6] a side view showing a mounting state of the linear actuator.
`[Explanation of Reference Signs]
`1.... actuator
`2.... case
`3.... shaft bearing portion
`3’.... protrusion
`4.... neck portion
`4’.... groove
`6.... screw
`7.... bearing
`8.... bearing
`9.... rotor
`10.... screw
`11.... rotor magnet
`12.... rotor magnet
`13.... stator coil
`14.... stator coil
`15.... mounting base plate
`16.... stopper
`17.... point stopper
`18.... setter
`19.... fitting groove
`20.... screw
`21.... cover
`22.... bottom
`23.... position detecting device
`24.... terminal
`25.... plastic magnet
`
`5
`
`10
`
`15
`
`20
`
`25
`
`6
`
`

`
`[Fig. 1]
`
`_F
`
`.i.
`
` eiflax.“
`
`
`
`-
`
`21
`
`2 2
`
`61..
`
`[Fig. 2]
`[Fig. 2]
`
`
`
`[Fig. 4]
`[Fig. 4]
`
`
`
`
`
`5
`
`
`
`[Fig. 3]
`
` [Fig. 5]
`
`
`
`
`
`7
`
`
`
`
`

`
`[Fig. 6]
`
`
`
`
`
`5
`
`
`
`Continued from Front Page
`
`(72) Inventor Hiroto Nakamata
`c/o R&D Center,
`MINEBEA Co., Ltd.,
`1743-1, Asana, Asaba-cho,
`Iwata-gun, Shizuoka-ken
`
`
`
`
`
`(72) Inventor Takahiro Iguchi
`c/o R&D Center,
`MINEBEA Co., Ltd.,
`1743-1, Asana, Asaba-cho,
`Iwata-gun, Shizuoka-ken
`
`8
`
`

`
`CERTIFICATE OF TRANSLATION
`
`I, Takuya Takahashi, of Tokyo, Japan, hereby certify that I am conversant
`
`in both Japanese and English and the following is,
`
`to the best of my
`
`knowledge and belief, a true and accurate translation of the original
`
`document from Japanese to English.
`
`I hereby acknowledge that any willful false statements and the like made in
`
`this Declaration are punishable by fine or imprisonment, or both (18 U.S.C.
`
`1001).
`
`Furthermore,
`
`I declare that all statements made of my own
`
`knowledge are true and all statements made on information and belief are
`
`believed to be true.
`
`Translated Material: JP H6-335228A
`
`Executed on this 6th day of October, 2015 at Tokyo, Japan.
`
`My
`
`Takuya Takahashi
`
`
`
`9