[19]
`United States Patent
`Terazawa et 31.
`Sep. 17, 1991
`[45] Date of Patent:
`
`[11] Patent Number:
`
`5,048,485
`
`[54] THROTTLE CONTROL METHOD FOR
`INTERNAL COMBUSTION ENGINE
`
`[75]
`
`Inventors:
`
`Tadashi Terazawa, Toyota; Hiroshi
`Nakashima, Nishio; Yoshinori
`Taguchi, Nagoya, .all of Japan
`
`[73] Assignee:
`
`Aisin Seiki Kabushiki Kaisha, Kariya,
`Japan
`
`[211 App]. No: 529,610
`
`[22] Filed:
`
`May 29, 1990
`
`Foreign Application Priority Data
`[30]
`May 29, 1989 [JP]
`Japan ................................. 1-135256
`
`Int. Cl.5 ......................... F02D 9/08; FOZD 41/02
`[51]
`[52] US. Cl. ..................................... 123/399; 123/400
`[58] Field of Search ........................ 123/361, 399, 400
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,120,373 10/1978 Fleischer ........................ 123/399 X
`
`1/1990 Asayama ...........
`.. 123/399 X
`4,892,071
`
`...... 123/399
`4,898,138
`2/1990 Nishimura et al.
`
`4,919,097 4/1990 Mitui et a1. .............. 123/399
`4,969,431 11/1991 Wataya ............................... 123/399
`
`Primary Examiner—Willis R. Wolfe
`Attorney, Agent, or Firm—Burns, Doane, Swecker &
`Mathis
`
`ABSTRACT
`[57]
`A throttle control method for an internal combustion
`
`engine wherein a motor is connected through a clutch
`mechanism to a throttle valve which is constantly bi-
`ased toward a closed position by a return spring. The
`motor is controlled in accordance with an output signal
`from a throttle sensor which detects the degree of open-
`ing of the throttle valve. This arrangement controls the
`amount of intake air into the internal combustion en-
`
`gine. The clutch mechanism is engaged and disengaged
`in accordance with a running condition of the vehicle
`and an operating condition of the internal combustion
`engine. An operating condition of the motor, the throt:
`tle sensor, the clutch mechanism and the return spring,
`is detected by activating the motor and the clutch
`mechanism, and when an abnormality is detected in at
`least one of the devices, both the motor and the clutch
`mechanism are deactivated.
`
`2 Claims, 10 Drawing Sheets
`
`
`[onuog
`
`lawn/IA7
`
`my..."//
`1,1.
`
`la]
`
`
`
`
`100
`
`b : End
`SP1: Engine at rest?
`SP2: Active motor and clutch mechanism
`SP3: Motor and throttle sensor normal ?
`SP4: inactive motor and clutch mechanism
`SP5: Clutch mechanism and return spring normal ?
`SP6: Control throttle opening to
`lower level than in norrnai throttle control
`SP7: Normal throttle control
`
`VW EX1006
`
`US. Patent No. 6,588,260
`
`VW EX1006
`U.S. Patent No. 6,588,260
`
`

`

`US. Patent
`
`Sep. 17, 1991
`
`Sheet 1 of 10
`
`5,048,485
`
`Fig.1
`
`
`
`a: Start
`
`b: End
`SP1: Engine at rest?
`SP2: Active motor and clutch mechanism
`SP3: Motor and throttle sensor normal ?
`SP4: Inactive motor and clutch mechanism
`SP5. Clutch mechanism and return spring normal ?
`SP6: Control throttle opening to
`lower level than'In normal throttle control
`
`SP7: Normal throttle control.
`
`

`

`US. Patent
`
`'
`
`Sep.17,1991
`
`Sheet 2 of 10
`
`5,048,485
`
`10
`
`
`
`Accelerator
`actuating
`mechanism .
`
`
`
`22 Return
`
`spring
`
`Throttle “4"“
`
`
`SGHSOF
`
`
`
`
`9 Internal combustion
`engine
`
`

`

`US. Patent
`
`Sep. 17, 1991
`
`sheet 3 of 10
`
`5,048,485
`
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`
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`

`

`US. Patent
`
`Sep. 17, 1991
`
`Sheet 4 of 10
`
`5,048,485 I
`
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`

`US. Patent
`
`Sep. 17, 1991
`
`Sheet 5 of 10
`
`5,048,485
`
`
`
`

`

`US. Patent
`
`’Sep. 17, 1991
`
`Sheet 6 of 10
`
`5,048,485
`
`
`
`a : Start
`b : End
`31 : lnitialization
`82: Input processing
`83: Control mode ?
`_
`S4: Normal accelerator control
`SS: Constant-speed running control
`86: Acceleration slip control
`S7: idling speed control
`88: Final processing
`89: Torque control
`810: Cornering control
`Si 1: Final processing / Diagnosis control
`81 2: Output processing
`
`.
`
`

`

`US. Patent
`
`Sep. 17, 1991
`
`Sheet 7 of 10
`
`5,048,485
`
`- a
`— 30‘
`«
`302
`a
`. - NO
`304 _
`
`Fig] '
`
`303
`
`
`
`a : Start
`b : First system check
`c : Second system check
`301: Main relay ON /Starter relay OFF /
`‘ Clutch mechanism OFF
`302: RAM normal ?
`303: RAM abnormality flag +- 1
`304: No disconnection or short-circuit ? .
`305: Disconnection / short-circuit abnormality flag ‘— 1
`306: System check starting conditions satisfied ?
`310: Throttle valve at idling position ?
`320: Clutch mechanism ON / Drive motor in valve opening
`direction through predetermined angle
`321: Predetermined change in opening 'of throttle valve ?
`322: Motor/throttle sensor abnormality flag +— 0-
`_
`
`

`

`US. Patent
`
`Sep. 17, 1991
`
`Sheet 8 of 10
`
`5,048,485
`
`Fig.8
`
`n
`
`330
`
`.
`
`a
`
`_
`.
`
`NO
`
`332
`340 _
`
`341
`
`. -YES
`
`NO
`
`9
`
`342
`
`' a
`
`b
`
`a _: Third system check
`b. Fourth system check
`330: Supply holding current to motor /
`Clutch mechanism OFF
`331. Throttle valve at initial position ?
`332: Return spring abnormality flag ‘- 0 /
`CIUtch mechanism abnormality flag +- O
`340: Suspend supply of holding current to motor
`341: Throttle valve return to initial position
`within predetermined time T ?
`.342: Return spring abnormality flag 1— 0 /
`Clutch mechanism abnormality flag +- 1
`
`

`

`US. Patent
`
`Sep. 17, 1591
`
`Sheet 9 of '10
`
`' 5,048,485
`
`9 350 I
`
`Fig.3
`
`a : Fifth system check
`b : Sixth system check
`c : System check end
`350: Drive motor in valve closing direction
`through predetermined angle
`351: Throttle valve closed
`‘
`to predetermined opening position ?
`352: Return spring abnormality flag ‘— 1
`/
`'
`Clutch mechanism abnormality flag ‘— 1
`360: Clutch mechanism ON /
`.
`Driving motor in valve closing direction
`'
`through predetermined angle
`361: System check 2nd time ?
`362: System check flag ‘— 1
`-
`370: System abnormality flag +- 1
`380: Main relay OFF / Clutch mechanism OFF /
`Motor OFF / Starter control relay ON
`
`.
`
`

`

`US. Patent
`
`,
`
`Sep. 17, 1991
`
`Sheet 10 of 10
`
`5,048,485
`
`Fig. 10
`
`
`a
`
`Throttle
`opening
`
` C I
`
`,
`n nomal
`Situation
`
`Fig. 1.1
`
`circuit
`
`100
`Timer
`Cil'CUlt Power
`
`Accelerator pedal
`actuating quantity less
`than predetermined valve?
`
`

`

`1
`
`5,048,485
`
`THROTTLE CONTROL METHOD FOR INTERNAL
`COMBUSTION ENGINE
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention relates to a throttle control
`method for an internal combustion engine. More partic-
`ularly, the present invention relates to a throttle control
`method wherein the degree of opening of the throttle
`valve is controlled by a motor, and the throttle valve
`and the motor are connected to each other and discon-
`nected from each other by a clutch mechanism.
`2. Description of the Related Art
`The throttle valve of an internal combustion engine is
`' arranged to control the output of the internal combus-
`tion engine by controlling either the fuel-air mixture in
`the case of a carburetor or the intake air quantity in the
`case of an electronically controlled fuel
`injector,
`in
`association with an accelerator actuating mechanism
`including an accelerator pedal connected to the throttle
`valve.
`
`The accelerator actuating mechanism has heretofore
`been mechanically coupled to the throttle valve. There
`has recently been proposed an apparatus wherein the
`throttle valve is opened and closed in accordance with
`the operation of the accelerator by a driving means
`which is interlocked With a driving source, for example,
`a motor. For example, Japanese Patent Laid-Open Pub-
`lication (KOKAI) No. 55-145867 (1980) discloses an
`apparatus wherein a stepping motor is coupled to the
`throttle valve and driven in accordance with the opera-
`tion of the accelerator pedal. Japanese Patent Laid-
`Open Publication (KOKAI) No. 59-153945 (1984) dis-
`closes a similar apparatus.
`~
`_
`It is, however, unclear in the above-described related
`art how to check as to whether or not each device, for
`example, a motor constituting the throttle control appa-
`ratus, is functioning normally. Generally, the motor and
`other constituent elements are individually checked,
`and when any of them is judged to be abnormal, the
`throttle control is suspended and the driver is informed
`that there is an abnormality in the throttle control appa-
`ratus. However, some functions of the constituent ele-
`ments of the throttle control apparatus, for example, the
`operating function of a throttle sensor, cannot be
`checked when the motor and other associated devices
`are in an inoperative state. Accordingly, it is necessary
`in order to check the operating function of each device
`to detect an operating condition of the motor and other
`devices. To detect an operating condition of each de-
`vice, the throttle valve must be opened and hence the
`rotational speed (RPM) of the internal combustion en-
`gine is undesirably raised, which makes the driver feel
`uncomfortable. There is also a fear that the vehicle
`speed will be uncontrollably increased.
`
`SUMMARY OF THE INVENTION
`
`It is an object of the present invention to provide a
`method for controlling a throttle for an internal com-
`bustion engine wherein the operating condition of each‘
`of the devices comprising a throttle control apparatus,
`for example, a motor, is detected and when any of the
`devices is abnormally functioning, a predetermined
`processing is executed.
`It is another object of the present invention to pro-
`vide a throttle control method which does not involve
`or permit an undesired rise in the rotational speed of the
`
`5
`
`10
`
`15
`
`20
`
`25
`
`3O
`
`35
`
`4O
`
`45
`
`50
`
`55
`
`60
`
`65
`
`-2
`internal combustion engine during the detection of an
`operating condition of each device of the throttle con-
`trol apparatus.
`invention provides a throttle control
`The present
`method for an internal combustion engine wherein a
`motor is connected through a clutch mechanism to a
`throttle valve which is constantly biased toward a
`closed position by a return spring. The motor is con—
`trolled in accordance with an output signal from a
`throttle sensor which detects the degree of opening of
`the throttle valve, thereby controlling the amount of
`suction or intake air into the internal combustion en-
`gine. The clutch mechanism is engaged and disengaged
`in accordance with a running or operating condition of
`the vehicle and the operating condition of the internal
`combustion engine. The method comprising detecting
`an operating condition of each of the devices, that is,
`the motor, the throttle sensor, the clutch mechanism
`and the return spring by activating the motor and the
`clutch mechanism, and deactivating both the motor and
`the clutch mechanism when an abnormality is detected
`in at least one of the devices.
`'
`The throttle control method may be such that an
`operating condition of each of the devices, that is, the
`motor, the throttle sensor, the clutch mechanism and
`the return spring is detected by activating the motor
`and the clutch mechanism, and when an abnormality is
`detected in eitherthe motor or the throttle sensor, both
`the motor and the clutch mechanism are deactivated,
`whereas, when the motor and the throttle sensor are
`detected to be normal and at
`least either the clutch
`mechanism or the return spring is abnormal, the throttle
`opening is controlled to a lower level than during nor-
`mal throttle opening control.
`Further, the above—described throttle control method
`may be such that the internal combustion engine is in-
`hibited from being started and maintained in an inopera-
`tive state while the motor and the clutch mechanism are
`being activated in order to detect the operating condi-
`tion of each of the devices, that is, the motor, the throt-
`tle sensor, the clutch mechanism and the return spring.
`The above-described throttle control method is exe-
`cuted, for example, as shown in the flowchart of FIG. 1.
`First,
`it is judged in Step SP1 whether or not the
`internal combustion engine is at rest. If YES, both the
`motor and the clutch mechanism are activated in Step
`SP2. As a result, the throttle valve is rotated against the
`return spring and the throttle sensor is activated. At this
`time, it is judged in Step SP3 whether, from the rela-
`tionship between the output of the throttle sensor and
`the angle of rotation of the throttle valve, if the motor
`and throttle sensor operations are normal. If either the
`motor or the throttle sensor is judged to be abnormal,
`the process proceeds to Step SP4, in which both the
`motor and the clutch mechanism are deactivated. If
`both the motor and the throttle sensor are judged to be
`normal in Step SP3, the process proceeds to Step SP5,
`in which it is judged whether or not both the clutch
`mechanism and the return spring are normal by, for
`example, judging whether or not
`the throttle valve
`returns to its initial position when the clutch mechanism
`is deactivated with the motor being supplied with a
`predetermined holding current.
`If either the clutch
`mechanism or the return spring is judged to be abnor-
`mal, the throttle opening is controlled to a lower level
`than during normal throttle opening control
`in Step
`SP6, whereas, if both arejudged to be normal. the pro-
`
`

`

`in which normal throttle
`
`3
`cess proceeds to Step SP7,
`control is executed.
`The above-described throttle control process may
`proceed as shown by the chain lines, with Steps SP1 and
`SP6 being omitted, or Step SP1 alone may be omitted.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The above and other objects, features and advantages
`of the present invention will become more apparent
`from the following description of the preferred embodi-
`ments thereof, taken in conjunction with the accompa-
`nying drawings, in which like reference numerals de-
`note like elements, and of which:
`FIG. 1 is a flowchart showing a throttle control
`method for an internal combustion engine according to
`the present invention;
`FIG. 2 is a block diagram showing the basic arrange-
`ment of a throttle control apparatus which may be em-
`ployed to carry out one embodiment of the throttle
`control method according to the present invention;
`FIG. 3 is an exploded perspective View of the throttle
`control apparatus shown in FIG. 2;
`FIG. 4 is a longitudinal sectiOnal view of the throttle
`control apparatus;
`FIG. 5 shows the general arrangement of the control-
`ler and input/output devices of the throttle control
`apparatus;
`FIG. 6 is a flowchart showing the overall perfor-
`mance of the throttle control apparatus shown in FIGS.
`2 to 5;
`FIGS. 7, 8 and 9 are flowcharts showing the process-
`ing routine of system checks for the throttle control
`apparatus;
`FIG. 10 is a characteristic chart showing the relation-
`ship between the accelerator opening and the throttle
`opening in another embodiment of the present inven-
`t1on;
`FIG. 11 is an electric circuit diagram concerning still
`another embodiment of the present invention; and
`FIG. 12 is a flowchart showing a part of another
`example of the system check shown in FIG. 7.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`throttle control
`the
`Preferred embodiments of
`method according to the present invention will be de-
`scribed below with reference to the accompanying
`drawings.
`Referring first to FIG. 2, which shows the basic ar-
`rangement of an apparatus which may be employed to
`carry out one embodiment of the throttle, control
`method according to the present invention, a throttle
`valve 11 is attached to an internal combustion engine 9
`and constantly biased in a closed direction by a return
`spring 22. A motor 50 is connected to the throttle valve
`11 through an electromagnetic clutch mechanism 40.
`The throttle valve 11 is'provided with a throttle sensor
`13. An output signal from the throttle sensor 13 is input-
`ted to a controller 100, together with signals which
`include a signal representative of the operating condi-
`tion of the internal combustion engine 9. Similarly, an
`output signal from an accelerator sensor 37 which is
`provided in an accelerator actuating mechanism 10 is
`inputted to the controller 100. The controller 100 is
`connected to a power supply VB. Thus, the electromag-
`netic clutch mechanism 40 and the motor 50 are oper-
`ated under the control of the controller 100.
`
`10
`
`15
`
`20
`
`25
`
`3O
`
`35
`
`4o
`
`45
`
`50
`
`55
`
`60
`
`65
`
`5,048,485
`
`4
`
`A specific arrangement of the above-described throt-
`tle control apparatus will be explained below in detail
`With reference to FIGS. 3 and 4. The throttle valve 11
`is rotatably supported by a throttle shaft 12 inside an
`intake passage in a throttle body 1 of an internal com-
`bustion engine. A casing or housing 2 is formed as an
`integral part of the side of the throttle body 1 where one
`end of the throttle shaft 12 is supported, and a cover 3
`is connected to the casing 2. The throttle sensor 13 is
`attached to the side of the throttle body 1 that isremote
`from the casing 2 and where the other end of the throt-
`tle shaft 12 is supported.
`The throttle sensor 13, which has a detector for de-
`tecting the degree of opening of the throttle valve 11, is
`connected to the throttle shaft 12 to detect an angular
`displacement of the throttle shaft 12 and convert it into
`an electric signal. For example, an idling switching
`signal and a throttle opening signal are outputted to the
`controller 100.
`A movable yoke 43'is rigidly secured to the other end
`of the throttle shaft 12 so that the throttle valve 11
`rotates together with the movable yoke 43 as one unit.
`As will be clear from FIG. 4, the movable yoke 43 is a
`circular dish-like magnetic member having a shaft por-
`tion that is rigidly secured to the throttle shaft 12. The
`movable yoke 43 is fitted to a fixed yoke 44, which is a
`magnetic member having substantially the same config-
`uration as that of the movable yoke 43, with a predeter-
`mined air gap provided therebctween in such a condi-
`tion that respective opening ends ofthe yokes face each
`other and the respective side walls and shaft portions
`are axially superposed one upon another. The fixed
`yoke 44 is rigidly secured to the throttle body 1. A coil
`45, wound around a bobbin 46 which is made of a non-
`magnetic material, is accommodated in a space that is
`defined between the shaft portion and side wall of the
`fixed yoke 44. A friction member 430 which is made of
`a nonmagnetic material is buried or positioned in a bot-
`tom wall of the movable yoke 43 such that the friction
`member 430 is disposed around the throttle shaft 12. A
`driving plate 41 is disposed so as to face the friction
`member 43a across a clutch plate 42 which is a disc—
`shaped magnetic member. Thus, the foregoing members
`comprise the electromagnetic clutch mechanism 40.
`The driving plate 41 is a circular dish-like member
`having a shaft portion in the center thereof, the shaft
`portion being supported on the throttle shaft 12 in such
`a manner as to be rotatable around it. The driving plate .
`41 has an external gear which is formed integral with
`the shaft portion thereof such that the external gear
`meshs with external
`teeth which are formed on the
`small-diameter portion of a gear 52 described later. The
`clutch plate 42 is coupled to the bottom surface of the
`driving plate 41 through a leaf spring 41a, as shown in
`FIG. 4. The clutch plate 42 is biased toward the driving
`plate 41 by'the action of the leaf spring 41a, so that the
`clutch plate 42 is kept separate from the movable yoke
`43 when the coil 451s not energized.
`The gear 52 thatIS meshed with the driving plate 41
`is a stepped columnar member having a small—diameter
`portion and a large-diameter portion which have re-
`spective external teeth, the gear 52 being supported by
`a shaft 520 which is rigidly secured to the 'cover 3 such
`that the gear 52 is rotatable around the shaft 52a. The
`motor 50 is secured to the cover 3 such that a rotary
`shaft of the motor 50 extends parallel to the shaft 520
`and is rotatably supported by a bearing arrangement. A
`gear 51 is rigidly Secured to the distal end of the rotary
`
`

`

`5
`shaft of the motor 50, the gear 51 being meshed with the
`external teeth formed on the large-diameter portion of
`the gear 52. In this embodiment, a stepping motor is
`used as the motor 50 and the drive of the stepping motor
`is controlled by the controller 100.
`Thus, when the motor 50 is driven to rotate the gear
`‘ 51, the gear 52 rotates, and the driving plate 41 that is
`meshed with the gear 52 rotates around the throttle
`shaft 12, together with the clutch plate 42. If the coil 45,
`shown in FIG. 4, is not energized at this time, the clutch
`plate 42 is kept separate from the movable yoke 43 by
`means of the biasing force from the leaf spring 41a.
`More specifically, in such a case, the movable yoke 43,
`the throttle shaft 12 and the throttle valve 11 are free to
`rotate independently of the driving plate 41. When the
`movable yoke 43 and the fixed yoke 44 are excited, the
`clutch plate 42 is attracted toward the movable yoke 43
`by means of electromagnetic force against the biasing
`force from the leaf spring 41a and eventually brought
`into contact with the movable yoke 43. Thus, the clutch
`plate 42 and the movable yoke 43 are brought into fric-
`tional engagement with each other. This frictional en-
`gagement and the action of the friction member 430
`together enable the clutch plate 42 and the movable
`yoke 43 to rotate together in the connected state. More
`specifically, in this case the driving plate 41, the clutch
`plate 42, the movable yoke 43, the throttle shaft 12 and
`the throttle valve 11 are driven to rotate together as one
`unit by the motor 50 through the gears 51 and 52.
`An accelerator shaft 32 is rotatably supported by the
`cover 3 in parallel to the throttle shaft 12, the outer end
`portion of the accelerator shaft 32 projecting from the
`cover 3. A rotary lever accelerator link 31 is secured to
`a projecting end portion of the accelerator shaft 32. A
`pin 330 which is rigidly secured to one end of an accel-
`erator cable 33 is engaged with the distal end of the
`accelerator link 31. The accelerator link 31 has a return
`
`5
`
`10
`
`15
`
`20
`
`25
`
`3O
`
`35
`
`spring 35 coupled thereto to bias both the accelerator
`link 31 and the accelerator shaft 32 in a direction corre-
`
`4O
`
`sponding to the direction in which the throttle valve 11
`is closed. The other end of the accelerator cable 33 is
`
`coupled to an accelerator pedal 34, thus constituting the
`accelerator actuating mechanism 10, in which both the
`accelerator link 31 and the accelerator shaft 32 rotate
`about the axis of the accelerator shaft 32 in response to
`the operation of the accelerator pedal 34.
`An accelerator plate 36 is rigidly secured to. the accel-
`erator shaft 32 at the portion thereof that extends be-
`tween the throttle body 1 and the cover 3, that is, inside
`the casing 2. A throttle plate 21 is secured to a small
`diameter portion 24 of the accelerator shaft 32 in oppos-
`ing relation to the accelerator plate 36.
`'
`The throttle plate21 is supported at the central por-
`tion thereof by the small-diameter portion 24 of the
`accelerator shaft 32 and comprises two portions which
`have a relatively small' radius and a relatively large
`radius, respectively, and which are circumferentially
`contiguous with each other. As shown in FIG. 3, exter-
`nal teeth are formed on the outer surface of the large-
`radius portion of the throttle plate 21. The external
`teeth of the throttle plate 21 are meshed with the exter-
`nal teeth formed on the aforementioned movable yoke
`43, so that the throttle plate 21 rotates in response to the
`rotation of the movable yoke 43, or the movable yoke
`43 rotates in response to the rotation of the throttle plate
`21, thus enabling unitary rotation of the throttle shaft 12
`and the throttle valve 11 that are connected thereto.
`
`45
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`50
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`55
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`6O
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`65
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`5,048,485
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`6
`In addition, the throttle plate 21 has a step which is
`formed at the joint of the small and large-radius por-
`tions, thus defining an end cam by the outer peripheral
`surface ofthe throttle plate 21. A pin 23 is secured to the
`large-radius portion of the throttle plate 21. One end of
`the return spring 22 is retained by the shaft portion of
`the throttle plate 21, and the other end of the return
`spring 22 is retained by a pin which projects from the
`casing 2. Accordingly, the throttle plate 21 is constantly
`biased by the force from the return spring 22 in the
`direction of the arrow B shown in FIG. 3, that is, in the
`direction in which the throttle valve 11 is closed.
`The accelerator plate 36 comprises a disc portion
`which is rigidly secured at the center thereof to the
`accelerator shaft 32 and an arm portion which radially
`extends from the disc portion. That portion of the disc
`portion which is contiguous with the arm portion has a
`relatively short radius to define a recess, thus defining
`an end cam by the outer peripheral surface of the disc
`portion. The arm portion is disposed such that one side
`surface that extends in the radial direction of the disc
`
`portion faces the pin 23 that is secured to the throttle
`plate 21. Thus, when the accelerator plate 36 rotates in
`the direction of the arrow A in FIG. 3, eventually the
`arm portion abuts against the pin 23 on the throttle plate
`21 and the accelerator plate 36 and the throttle plate 21
`rotate together as one unit. It should be noted that the
`accelerator plate 36 has a pin 36c which projects there—
`from in the axial direction of the accelerator shaft 32.
`Thus, the accelerator plate 36 and the throttle plate 21
`'shown in FIG. 3 are in their initial positions. When the.
`driving plate 41 is connected to the movable yoke 43 by
`the electromagnetic clutch mechanism 40. the throttle
`valve 11 is driven to rotate by the motor 50.
`An accelerator sensor 37 is fitted on the outer periph-
`ery of an accelerator shaft bearing portion formed on
`the cover 3. The accelerator sensor 37 has a known
`structure which comprises a member formed with a
`thick film resistor and a brush which faces the resistor.
`The accelerator sensor 37 is disposed so that the brush»
`is engaged with the pin 36c provided on the accelerator
`plate 36. Thus, the angle of rotation of the accelerator
`shaft 32 that rotates together with the accelerator plate
`36 as one unit is detected by the accelerator sensor 37.
`The accelerator sensor 37 is electrically connected to a
`printed wiring board 70 which is interposed between
`the casing 2 and the cover 3. The printed wiring board
`70 is electrically connected to the controller 100
`through lead wires 71.
`A limit switch 60 which operates in association with
`the throttle plate 21 and the accelerator plate 36 is se-
`cured to the casing 3 through a stay or support member,
`as shown in FIG. 4, and electrically connected to the
`printed wiring board 70. The limit switch 60 has oppos-
`ing contacts (not shown) and a roller 63 which is at-
`tached to the distal end portion of the limit switch 60.
`The roller 63 is constantly biased so as to abut on the
`outer peripheral surfaces of the throttle plate 21 and the
`accelerator plate 36, as will be clear from FIGS. 3 and
`"4. Accordingly, the roller 63 moves in accordance with
`the profiles of the end cams respectively formed on the
`throttle plate 21 and the accelerator plate 36, so that the
`opposing contacts come in and out of contact with each
`other in response to the cam following action of the
`roller 63. The opposing contacts of the limit switch 60
`are in contact with each other except when the acceler-
`ator pedal 34 is stepped on or depressed less than a _
`'predetermin'ed accelerator actuating quantity.
`that
`is,
`
`

`

`7
`the angle of rotation of the accelerator plate 36 is less
`than a predetermined angle, and the throttle plate 21 is
`driven to rotate in excess of a predetermined angle.
`Thus, when the accelerator pedal 34 is stepped on less
`than a predetermined accelerator actuating quantity, for
`example, when the accelerator plate 36 is in the state
`that is shown in FIG. 3, i.e., the accelerator actuating
`quantity is approximately zero, and the throttle valve 11
`is opened in excess of a predetermined angle, that is, the
`throttle plate 21 rotates in the direction of the arrow A
`in FIG. 3 in excess of a predetermined angle, the roller
`63 abuts on the respective small-radius portions of the
`throttle and accelerator plates 21 and 36 and conse-
`quently the opposing contacts are separated from each
`other.
`-
`The controller 100, Which is a control circuit includ-
`ing a microcomputer,
`is mounted on the vehicle and
`supplied, as input signals, with detecting 'signals from
`various sensors, as shown in FIG. 5, thereby effecting
`various 'control operations including the drive control
`of the electromagnetic clutch mechanism 40 and the
`motor 50. In this embodiment, the controller 100 effects
`various control operations such as constant-speed run-
`ning control, acceleration slip control, etc. in addition
`to the control usually effected in response to the opera-
`tion of the accelerator pedal 34.
`Referring next to FIG. 5, the controller 100 has a
`microcomputer 110 and input and output processing
`circuits 120 and 130, which are connected to the mi-
`crocomputer 110. The motor 50 is connected to the
`output processing circuit 130. The coil 45 ofthe electro-
`magnetic clutch mechanism 40 is connected to the out-
`put processing circuit 130 through first and second
`energizing circuits 101 and 102. The controller 100 is
`connected to the power supply VB through an ignition
`switch 99. In addition, a main relay (not shown) is pro-
`vided as a means for opening and closing the respective
`power circuits of the coil 45 and the motor 50. The main
`relay 109 supplies electric power to these power circuits
`when the 'ignition switch 99 is turned on. The main
`relay 109 may be replaced with another kind of switch-
`ing element, for example, a transistor. It should be noted
`that the controller 100 has a backup power supply (not
`shown) to store an operating condition of each constitu-
`ent element of the throttle control apparatus that is
`detected in a system check processing (described later).
`The accelerator sensor 37 is connected to the input
`processing circuit 120 to output a signal corresponding
`to the accelerator actuating quantity, that is, the amount
`to which the accelerator pedal 34 is stepped on or de-
`pressed. Thus, the output signal from the accelerator
`sensor 37 is inputted to the input processing circuit 120,
`together with the output signal from the throttle sensor
`13. The controller 100 controls the electromagnetic
`clutch mechanism 40 in accordance with operating
`conditions, thereby controlling the drive of the motor
`50 so as to obtain a degree of opening of the throttle
`valve 11, i.e., a throttle opening, which is set in accor-
`dance with the amount to which the accelerator pedal
`34 is stepped on, i.e., accelerator opening, together with
`the operating condition of the internal combustion en-
`gine and the running condition of the vehicle.
`,
`‘
`A switch 80 for constant-speed running control (here-
`inafter referred to simply as “constant-speed running
`switch 80) is connected to the input processing circuit
`120. The constant-speed running switch 80 comprises a
`main switch 81 which is actuated to turn on/off the
`
`power supply for the whole constant-speed running
`
`5
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`10
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`15
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`20
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`25
`
`30
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`35
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`4O
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`45
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`50
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`55
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`6O
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`65
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`5,048,485
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`8
`control system, and a control switch 82 which is used to
`effect various control operations. The control switch 82
`comprises a plurality of switches, as shown in FIG. 5,
`thus providing known various switching functions. In
`the figure, reference symbol AC denotes an accelerator
`switch, ST a set switch, CA a cancel switch, and RS a
`resume switch.
`A wheel speed sensor 91 is used for constant-speed
`running control, acceleration slip control, etc. As the
`wheel speed sensor 91, a known electromagnetic pickup
`sensor, e.g., a Hall sensor may be employed. Although
`one wheel speed sensor 91 is shown in FIG. 5, a plural-
`ity of sensors 91 may be attached to all the wheels,
`respectively, if necessary. Further, an ignition circuit
`unit 92, which is commonly known as an ignitor,
`is
`connected to the controller 100 to input thereto the
`ignition signal, thereby detecting the number of revolu-
`tions (RPM) of the internal combustion engine.
`A transmission controller 93, which is an electronic
`controller that COntrols an automatic transmission, de-
`tects an operating condition of the internal combustion
`engine and a running condition of the vehicle from
`signals which are inputted thereto from the wheel speed
`sensor 91, the throttle sensor 13, etc., computes a gear
`position and other necessary data on the basis of these
`input signals by means of a microcomputer, and outputs
`a gear-changing