United States Patent (19)
`Sieber
`
`|||||||||||||
`US00518429A
`11
`Patent Number:
`5,181,429
`45
`Date of Patent:
`Jan. 26, 1993
`
`(54)
`(75)
`
`HEADLAMP POSITONING DEVICE
`Inventor: Edmond Sieber, Donatyre,
`Switzerland
`Assignee:
`Saia AG, Switzerland
`(73)
`Appl. No.:
`(21)
`734,928
`Jul. 24, 1991
`22)
`Filed:
`Foreign Application Priority Data
`30
`Jul. 26, 1990 (CH) Switzerland....................... 02486/90
`51) Int. Cl......................... F16H 27/04; H02P 8/00;
`B60Q 1/06
`52 U.S. C. ................................... 74/89.15; 318/696;
`362/66; 362/273; 362/287
`58) Field of Search ............................ 74/89.15, 89.16;
`362/66, 69,273, 287, 289, 428; 318/696
`References Cited
`U.S. PATENT DOCUMENTS
`3,802,281 4/1974 Clarke....
`... 74/89.15
`4,179,944 12/1979 Conner ...
`... 74/89.5
`4,524,407 6/1985 Igura ......
`... 362/273 X
`4,567,434 1/1986 Lindig ...
`... 318/696 X
`4,655,567 4/1987 Morley ............................. 362/66 X
`4,719,810 1/1988 St. Cyr et al
`... 74/89.15
`4,791,343 12/1988 Ahrendt .............................. 318/696
`
`56)
`
`4,841,790 6/1989 Williston et al. .................. 74/89.15
`4,843,523 6/1989 Nakamura ............................. 362/69
`4,863,410 7/1988 Kressirer et al.
`... 31.8/696
`4,876,906 10/1989 Jones .................................. 74/89, 15
`4,884, 174 11/1989 Dorleans ......
`... 362/287 X
`4,916,587 4/1990 Hirose et al. ...
`... 362/289 X
`4,967,319 10/1990 Seko .................................. 362/66 X
`FOREIGN PATENT DOCUMENTS
`0182774 5/1986 European Pat. Off. .
`0340735 11/1989 European Pat. Off. .
`2471883 6/1981 France .
`61-64548 4/1986 Japan .
`90/07440 7/1990 PCT Int'l Appl. .
`Primary Examiner-Leslie A. Braun
`Assistant Examiner-Ryan W. Massey
`Attorney, Agent, or Firm-Ostrolenk, Faber, Gerb &
`- Soffen
`ABSTRACT
`57
`A headlamp positioning device having a stepping motor
`and a sensor for detecting loss of steps in the motor. An
`electronic controller operating in open-loop with the
`motor automatically reinitiates the positioning upon the
`detection of loss of steps due to an impediment during
`the positioning of the headlamps.
`
`15 Claims, 3 Drawing Sheets
`
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`VWGoA EX1034
`U.S. Patent No. 9,955,551
`
`

`

`U.S. Patent
`
`Jan. 26, 1993
`
`Sheet 1 of 3
`
`5,181,429
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`U.S. Patent
`
`Jan. 26, 1993
`
`Sheet 2 of 3
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`5,181,429
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`

`

`U.S. Patent
`
`Jan. 26, 1993
`
`Sheet 3 of 3
`
`5,181,429
`
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`CONTROL OF
`MOTOR
`
`
`
`
`
`OPEN LOOP
`
`
`
`
`
`DETECTION OF
`LAST STEPS
`
`F.G.5
`
`STEPPING
`MOTOR
`
`

`

`1
`
`HEADLAMP POSITIONING DEVICE
`
`able.
`
`-
`
`5,181,429
`2
`tained with such error margin that the system is unsuit
`Thus, the problem of the reliability of the positioning
`devices, and above all of the precision of their opera
`tion, still remains unresolved. It is fundamental, how
`ever, from the moment the motor is switched on, to
`bring the headlamp of a car from position "1" to posi
`tion "2", the latter should be effectively reached by the
`headlamp with a tolerance as small as possible and inde
`pendent of the environmental conditions of use. There
`fore, in a preferred device, the absolute error in posi
`tioning of the headlamps of a car should not exceed 0.1
`mm. Moreover, it is necessary that the position attained
`be maintained in spite of external stress in order to fully
`benefit from the advantages of the relatively precise
`positioning. The solution to these problems is depen
`dent on the precision which can be attained in the axial
`play, which should not exceed 0.05 mm, for the field of
`application of the present invention.
`SUMMARY OF THE INVENTION
`Accordingly, an object of the present invention is to
`eliminate the observed drawbacks in the known de
`vices, and to propose solutions for the problems men
`tioned, by providing a positioning device which is reli
`able and of good quality. Another object is to provide a
`positioning device for positioning at least one element
`which can occupy different predetermined positions
`between two extreme positions. The element is coupled
`to a driving shaft driven by a stepping motor, and in
`cludes means for reinitiating the counting of the number
`of steps, the stepping motor being controlled by an
`open-loop control.
`A device invented by the same applicant, described in
`the Swiss patent application no. 1980/90, is incorpo
`rated herein by reference. Using this device, comprising
`a detector for loss of synchronization, the position of
`the driving shaft capable of axially shifting, is deter
`mined indirectly by counting the number of steps. If an
`incorrect stop, consisting of an accidental abutment
`arises, the error of positioning is signalled by the detec
`tion of the lost steps, resulting in the driving shaft trav
`elling back against a back stop in order to reinitiate the
`counting operation. Thus, there is provided an open
`loop adjustment without a physical element, like a po
`tentiometer, being necessary for indicating the position
`of the shaft.
`Other features and advantages of the present inven
`tion will become apparent from the following descrip
`tion of the invention which refers to the accompanying
`drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 shows schematically the device utilized for
`the adjustment of the position of the headlamps of a car;
`FIG. 2 shows a section of a first embodiment of the
`device along its plane of symmetry;
`FIG. 3 shows in detail a portion of FIG. 2;
`FIG. 4 is a schema explaining the positioning;
`FIG. 5 is a block diagram illustration of the electronic
`controller system for detecting lost steps and reinitializ
`ing the counting of steps; and
`FIG. 6 is a section of a second embodiment of the
`device along its plane of symmetry.
`
`5
`
`35
`
`BACKGROUND OF THE INVENTION
`The present invention relates to a positioning device,
`in particular a device having at least one element capa
`ble of occupying different predetermined positions be
`tween two extreme positions. The element being cou
`pled to a driving shaft driven by a stepping motor.
`10
`Devices of this kind often comprise different mechan
`ical elements, some of which are mounted with axial
`play not exceeding a previously assigned limit in order
`to make the device capable of operating in conformity
`with required criteria of precision and reliability. Con
`sequently, the present invention also relates to a method
`of adjustment of such axial play.
`Such devices can be used in different areas requiring
`the same kind of technical application. A preferred
`application is in the positioning of the optics or head
`20
`lamps of a car.
`The positioning of optics of a car can be done in
`different ways. Frequently a direct current or DC
`motor is used. A potentiometer transmits the position of
`the driving shaft to a control device (which in this appli
`25
`cation is axially displaceable), that is an indication of the
`position of the shaft at a given time. The maintenance of
`this position is executed as a function of a given signal.
`It concerns, therefore, a control of the analog type
`working in a close-loop.
`30
`It is, however, observed that drivers using a DC
`motor are not satisfactory for the following reasons.
`First, with known devices, a problem of compatibility
`is encountered because of the increasing use of digital
`controls. It is desirable that the positioning device be
`connected to a microprocessor, which is not feasible in
`the case of a DC motor.
`Second, it is observed that the potentiometer is ex
`posed to wear, and change in its operation is accelerated
`as a result of the environmental conditions of use, such
`as a high temperature range. For these reasons, the
`accuracy of positioning is not ensured in spite of me
`chanical gearing down provided on most of the known
`devices.
`Patent application EP-A-0340 735 discloses a device
`45
`for the adjustment of the inclination of a headlamp of a
`car, that is, of the light beam. This adjustment requires
`a stepping motor having a direction of rotation and
`number of turns dependent on a microprocessor, and a
`control unit for the signals received from an optical
`50
`sensor having five elements E1 to E5. However, the
`patent does not disclose or suggest any means for repo
`sitioning the optical beam, nor for taking up the axial
`play.
`Patent application EP 0182774 describes the prob
`55
`lem of correcting the position of the element to be ad
`justed; a correction necessary because of the loss of
`steps of the stepping motor. The solution proposed in
`this case consists of momentarily delivering a deter
`mined higher current to the motor, if the number of
`60
`steps to be executed and the number of effectively real
`ized steps are different.
`This solution presents, among others, the drawback
`of creating an excessive stress on the stepping motor as
`a function of the extent of the obstacle to overcome,
`which renders the correction necessary. Moreover, this
`approach generates disturbances in the stepping motor
`so that the desired position may not be attained or at
`
`65
`
`

`

`10
`
`15
`
`3
`DESCRIPTION OF EMBODIMENTS OF THE
`INVENTION
`Referring to FIG. 1, positioning device 1, utilized for
`the adjustment of an optic of a car 3, in its protective
`cover 8 is shown. The optic 3 is pivotally mounted on a
`shaft 4. The driving shaft 2 of the device 1 is connected
`to the articulation 7 through a spherical coupling 5 and
`an actuating rod 6. As a function of the load of the car,
`that is of its seat and its axial inclination, data which is
`detected for example by sensors (not represented), the
`position of the optic 3 will be automatically corrected
`by a control not represented. As a function of the re
`ceived information, the shaft 2 will be shifted axially
`either toward the right (in FIG. 1), thereby effecting a
`translatory motion towards the outside, or towards the
`left, that is effecting a translatory motion towards the
`inside. These translatory motions cause the optic 3 to
`pivot about the shaft 4 to a position corresponding to a
`correctly directed beam. In less sophisticated embodi
`20
`ments, the control of the device 1 can be manually
`actuated by the driver of the car using a knob on the
`dashboard of the car.
`Referring to FIGS. 2 and 4, the device 1 has two
`portions: A motor portion having an axis 9 and a driving
`25
`portion having an axis 10. The constitutive elements of
`the driving portion are enclosed in a cover 11. The
`motor portion includes the actuator or stepping notor
`12 with a rotor shaft 13 on which is mounted a pinion 14
`attached to it in rotation and translation, the pinion 14
`30
`forming the first element of a gear down mechanism.
`Moreover, as will be seen later on, it is absolutely neces
`sary that the stepping motor 12 (preferably of the re
`verse type) be controlled by an electronic controller
`system for detecting the lost steps. This control, which
`35
`is known to persons of ordinary skill in the art, is sche
`matically represented in FIG. 5. The control circuit for
`the motor receives the output information from a detec
`tor which detects a loss of steps taken by the stepping
`motor and accordingly reinitiates the counting of steps
`when the motor is stopped by one of the stops 30, 31
`shown in FIG. 4.
`The driving portion has a wheel 15 gearing with the
`pinion 14 and forming the second element of the gear
`down mechanism, the reduction ratio of which is i. The
`45
`hub 16 of the wheel 15 is provided with a threaded bore
`17. The wheel 15 is mounted on the threaded part 19 of
`the driving shaft 2. The driving shaft 2 is bound into
`rotation by means of the extremity 18 presenting a
`square cross-section and being guided into a recess 21,
`50
`the bottom 22 of this recess serving in this embodiment
`as a stop preventing the axial shifting of the shaft 2. The
`shaft 2 is supported on one side of the hub 16 by its
`extremity 18 and on the other side of the hub 16 by a
`bushing 23 bearing the portion 24 of the shaft 2. The
`55
`shaft 2 also comprises the output shaft 20 projecting
`from the bushing 23 and reaching a spherical coupling
`(not represented in FIG. 2). The bushing 23 is mounted
`rigidly locked (as will be seen later on) in bearing 32 of
`the cover 11. The distance from the face 27 of the recess
`60
`21 to the face 28 of the bushing 23 is sufficient to allow
`a small functional play to the hub 16 as will be seen later
`on (see FIG. 3).
`The operation of the device, the stepping motor of .
`which is controlled by an electronic controller system
`65
`for detecting lost steps, is as follows (FIGS. 1, 2 and 4).
`FIG. 4 represents a device G and a device D, respec
`tively, coupled to the left headlamp and to the right
`
`5,181,429
`4.
`headlamp of a car, the predetermined conditions are
`represented by "O", "1", "2", "3", "4" and “5” (posi
`tions designated by "0" and "j" in FIG. 1). The position
`of the headlamp is variable as a function of the load of
`the vehicle. The load in the car can vary the direction of
`the axis of the headlamp with respect to the road.
`In a first illustrated case, it is determined that the
`device must pass from the normal position "0" to the
`position “4” indicated by the arrows A in FIG. 4. When
`the stepping motor 12 is switched on, the wheel 15 is
`rotated. The threaded hub 16 and the threaded part 19
`of the shaft 2, bound into rotation, constitute a screw
`nut system 17, 19 so that the shaft will undergo an axial
`shifting from the start position "0" to the desired posi
`tion "4". Apart from the problem of axial play, this
`particular case does not pose any difficulty with regard
`to the precision of the positioning since the disadvan
`tages created by the use of potentiometers are elimi
`nated in the device. Difficulty in positioning will be
`encountered when the advance or the recoil of the shaft
`is hindered by an external cause, e.g. freezing of the
`condensation water in winter or after voluntary reinitia
`ting (resetting), causing the stepping motor to travel
`against the rear stop 30, in FIG. 4, corresponding to the
`reference 22 in FIG. 2. In FIG. 4, the arrows B illustrate
`a case in which after having selected the position "3",
`only the right device D reaches this position while the
`left device G is blocked between the positions "1" and
`"2", corresponding to an accidental stop 31. During
`normal operation, that is, without any incident in the
`advancing of the shaft 2, the number of steps is counted,
`however, an accidental stop as well as the rear stop of
`reinitiating, can cause a loss of steps, the number of
`which is not counted and hence not known.
`The operation in open-loop to overcome the problem
`in positioning of the device is best understood by the
`example of reinitiating, that is when the shaft 2 is
`brought against the rear stop 30, and the precision of
`positioning and its reliability are ensured by the means
`disclosed in the present invention. At the time of abut
`ment, the rotor still receives pulses but there is no rota
`tion. In fact, any stop during the travelling of the shaft
`2 can induce the stepping motor to operate backwards
`by one or more preceding electrical cycles, either of
`four steps or of a multiple of four steps, this number
`being dependent on the elasticity of the stop. As already
`mentioned, the lost steps during this phase are not
`counted by the electronic control. However, experi
`ments and measurements have shown that in practically
`all cases the number of lost steps never exceeds eight.
`When the shaft moves from the stop 30, for example,
`by 50 steps to reach the position "0", the actual number
`of steps is not known. The actual number of steps may
`be, for example, forty six if the jump against the stop
`corresponds to a cycle of four steps. The resolution r,
`defined as the axial shifting of the shaft-without reduc
`tion-corresponding to one step of the motor, is given
`by a/360Xp, where a is the angular step of the motor
`and p the thread of the screw-nut system 17, 19. For a
`set of values such as a = 15 and p=0.8 mm, r=0.033
`mm/driving step. Assuming the loss of eight steps the
`error will be 8x0.033=0.264 mm, an error which is
`much greater than the level 0.1 mm which is permitted
`for this range of application. An appropriate reduction
`ratio permits division of this error so that the predeter
`mined level is not exceeded. In this example, a ratio of
`reduction of three would be sufficient. This ratio could
`be greater if the number of lost steps is greater than
`
`

`

`10
`
`20
`
`5,181,429
`6
`5
`eight. In practice, experiments have shown that with a
`In order to limit the friction, a pressure P is exerted
`on the frontal part 29 of the housing 11, the force being
`reduction ratio of i= 6, a relatively high factor of secu
`transmitted to the bearing 32 after the wheel 15 and the
`rity is achieved so that error in positioning is always
`shaft 2 have been assembled. Then, the bushing 23 is
`significantly smaller than 0.1 mm; i.e., a relative error
`introduced until the face 28 comes in abutment against
`less than 1% for a shifting of 10 mm.
`the face 26 of the hub 16. The pressure, the value of
`The same reasoning applies if an accidental stop 31
`which is a function of the rigidity of the material chosen
`occurs. In this case, due to the loss of steps, error in
`for the housing, will produce a resilient shifting d of the
`positioning is signalled by the detection of the lost steps,
`bearing 32 towards the inside of the housing. See FIG.
`and the shaft 2 will go back against the rear stop for
`2. The pressure is chosen so that d = 0.02 mm maximum.
`reinitiating the count. Then, the shaft 2 will go forward
`The fixed joining of the bushing 23 and the housing 11
`to the desired position which, if the stop 31 is no longer
`is effected while the pressure is maintained, preferably
`present, will be reached with the required precision.
`by ultrasonic welding. After this joining is executed, the
`In FIG. 6, a second embodiment of the invention is
`pressure is removed so that the parts 29, 32 recoil by a
`shown, in which manual adjustment means for resetting
`distance equal, or approximately equal to d, carrying
`15
`are provided at the rear part of the driving portion. The
`away the bushing 23 and thus freeing the hub of the
`manual adjustment means permit adaptation of the posi
`wheel while limiting the amount of play. The definitive
`tioning device to various types of headlamps, and to
`play will thus be 0.02 augmented by the play of the
`effect, if necessary, a periodic correction. Accordingly,
`threads of the screw-nut system 17, 19, thus, greater
`the driving shaft 36 has as its rear extremity a polygonal
`than 0.02 mm, but in all cases, lower than 0.05 mm
`section 37 which is axially adjustable (a different posi
`which constitutes the maximum limit for the play that
`tion 37' is represented in dotted lines, as an example) in
`must not be exceeded.
`the recess 38 of a threaded ring 39 screwed in the
`Although the present invention has been described in
`threaded recess of the housing 50, the thread being
`relation to particular embodiments thereof, many other
`identical to the one of the screw-nut system 17, 19. The
`variations and modifications and other uses will become
`25
`friction of the threads of the ring 39, in the correspond
`apparent to those skilled in the art. It is preferred, there
`ing threading in the housing 50, must be greater than the
`fore, that the present invention be limited not by the
`friction of the screw-nut system. The threaded ring 39
`specific disclosure herein, but only by the appended
`produces, when rotated by a pin 35, an axial shifting of
`claims.
`the driving shaft 36 corresponding to the axial shifting
`I claim:
`30
`of the threaded ring 39. Thus, the driving shaft 36 asso
`1. A device for positioning an element capable of
`ciated with the axial rear stop (that is of the polygonal
`attaining different predetermined positions between
`section 37 on the pin 35) can take an initial position
`two extreme positions, comprising a driving shaft cou
`adapted to the type of headlamp. Instead of a pin, it is
`pled to said element, said driving shaft being driven by
`also possible to provide any other suitable actuating
`a stepping motor, said device including means for
`element.
`counting steps taken by said stepping motor and reinitia
`The aforementioned device has been described by
`ting said counting, said stepping motor being controlled
`means of an example where the driving shaft of the
`by an open-loop control.
`element to be positioned executes an axial shifting, the
`2. The device according to claim 1, further compris
`element itself, that is the headlamp of a car, pivoting
`ing means for detecting a loss of steps taken by said
`about the shaft 4 (see FIG. 1). However, the invention
`stepping motor to detect an error in positioning of said
`is not limited to solely axial positioning of the driven
`element.
`element but extends also to other possibilities for angu
`3. The device according to claim 2, wherein said
`lar positioning of the latter by means of a gear train.
`driving shaft is connected to a rotor of said stepping
`In the case of axial positioning of the driving shaft,
`motor through a gear reduction system having a speci
`45
`part of the advantages derived by the precise position
`fied reduction ratio.
`ing would be vitiated if the axial shifting of the shaft 2
`4. The device according to claim 2, further compris
`was affected by an axial play, which although unavoida
`ing means for signalling an error in positioning after a
`ble, has, therefore, to be kept relatively small and must
`predetermined number of unsuccessful positioning at
`remain constant. Particularly, in the range of applica
`tempts have been tried.
`tions for the adjustment of headlamps of a car, a rela
`5. The device according to claim 1, wherein said
`tively large axial play would lead to almost continuous
`driving shaft is connected to a rotor of said stepping
`oscillation of the light beam, such a situation being
`motor through a gear reduction system having a speci
`particularly undesirable.
`fied reduction ratio.
`In FIGS. 2 and 3, it is observed that if the faces 25, 26
`6. The device according to claim 5, wherein said
`55
`rotor further comprises an output shaft, said gear reduc
`of the hub 6 of the wheel 15 come in contact with the
`faces 27, 28, respectively, due to the mounting of the
`tion system comprises a first gear element mounted on
`bushing 23 (e.g. by driving it in the bearing 32 of the
`said output shaft of said rotor and a second gear element
`housing”), force of friction between the various parts
`coacting with said first gear element, said second gear
`would have to be overcome by the stepping motor.
`element being mounted on said driving shaft, said driv
`ing shaft further comprising a threaded part and having
`Motors of small power utilized in these types of devices
`a predetermined axial movement.
`would not be suitable any more. Further, the utilization
`7. The device according to claim 1, further compris
`of motors of greater power would be too expensive for
`ing one or more stops, said reinitiating of counting tak
`such devices.
`ing place when said stepping motor is stopped by one of
`The present invention also provides a method for
`limiting the axial play to a maximum of 0.05 mm, such a
`said stops.
`m
`8. The device according to claim 7, wherein at least
`method not being limited to the described positioning
`one of said stops is adjustable.
`devices.
`
`35
`
`50
`
`65
`
`

`

`5,181,429
`7
`8
`counting of steps and being controlled by an open
`9. The device according to claim 8, further compris
`loop control;
`ing means for positioning said driving shaft at an initial
`(b) positioning a first face of said hub of said gear
`position corresponding to a predetermined position of
`component against a means for limiting axial move
`said element.
`ment of said gear component in one direction;
`10. The device according to claim 1, wherein said
`(c) positioning a bushing against a second face of said
`driving shaft is rotationally coupled to said stepping
`hub of said gear component, said bushing limiting
`motor and is movable axially, said rotational movement
`axial movement of said gear component in a direc
`being converted to translatory movement by means of a
`tion opposite to said first direction, said bushing
`screw and nut system, said screw and nut system per
`being disposed in a bearing;
`10
`mitting said translatory movement to take place over a
`(d) exerting pressure on said bearing towards said hub
`of said gear component in order to resiliently shift
`defined distance.
`said bearing by a distanced;
`11. The device according to claim 1, wherein said
`(e) joining said bushing and said bearing; and
`element is the headlamp of an automobile.
`(f) removing said pressure from said bearing.
`12. A method for assembling a gear component of a
`13. A method according to claim 12, wherein said
`gear reduction system of a device for positioning an
`distance d is 0.02 mm.
`element capable of attaining different predetermined
`14. A method according to claim 12, wherein said
`positions between two extreme positions, comprising
`bushing and said bearing are joined by ultrasonic weld
`the steps of:
`ling.
`20
`(a) mounting said gear component having a hub on a
`15. A method according to claim 13, wherein said
`bushing and said bearing are joined by ultrasonic weld
`driving shaft coupled to said element, said driving
`shaft being driven by a stepping motor, said step
`1ng.
`ping motor comprising means for reinitiating
`
`s
`
`15
`
`25
`
`30
`
`35
`
`45
`
`SO
`
`55
`
`65
`
`