Abstract:
A throttle controller includes a main body to which is connected a body cover which accommodates therein a power transmitting mechanism constituted by a pinion gear, a secondary gear, and a final gear. Accommodated in the body cover are a built-in throttle sensor and a lever connecting the throttle sensor and the throttle shaft. The throttle controller is less complicated in construction, requiring a smaller number of parts, and allows realization of reduced production cost as compared to other known constructions. In addition, the assembly of the throttle sensor is easier.

Description:
This application is based on and claims priority under 35 U.S.C. §119 with respect to Japanese Application No. 10(1998)-308394 filed on Oct. 29, 1998, the entire content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to vehicle throttles. More particularly, the present invention pertains to a throttle control device associated with internal combustion engines for adjusting the amount of opening of a throttle valve by driving a motor connected to the throttle in response to the amount of depression of the acceleration pedal. 
     BACKGROUND OF THE INVENTION 
     Japanese Patent Laid-Open Publication No. Hei. 6-264779 published on Sep. 20, 1994 without examination discloses a known throttle control device that includes a throttle valve for adjusting the amount of air passing through the intake passage of an internal combustion engine and a throttle body in which is accommodated the throttle valve. The throttle body rotatably supports a throttle shaft to which the throttle valve is fixed. A motor is coupled to the throttle valve via a power transmission mechanism for open/close driving of the throttle valve, and a throttle sensor determines the opening amount of the throttle valve. A cover is also secured to the throttle body for accommodating the power transmission mechanism in a space between the cover and the throttle body. 
     In this known throttle control device, when the acceleration pedal is depressed, the resultant depression amount is determined by a throttle sensor. A signal indicative of the depression amount of the acceleration pedal is issued from the throttle sensor and the motor is driven to rotate the throttle valve through an angle in response to the signal. Thus, the amount of air to be taken into the internal combustion engine is adjusted. Such an adjustment is established with well-known feedback control or PID control (Proportion-Integration-Differential Control) in such manner that the actual opening amount of the throttle valve which is indicated by the signal from the throttle sensor is compared to a target opening amount of the throttle valve which is indicated by the signal of the acceleration sensor for converging the deviation between the two values to zero. 
     However, with the above-construction, the cover and the throttle sensor are provided separately, thus requiring an independent fixation mounting of each of the cover and the throttle sensor to the throttle body. Thus, the number of parts is increased, with the result that the production cost is increased and the assembly of the device is more complicated. 
     Accordingly, a need exists for a throttle control device that is not as susceptible to the foregoing disadvantages and drawbacks. 
     It would thus be desirable to provide a throttle control device possessing a simpler construction and capable of being more easily assembled and with a lower production cost. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, a throttle control device includes a throttle body, a throttle shaft journalled on the throttle body, a throttle valve accommodated in the throttle body and mounted on the throttle shaft for adjusting an amount of air passing through the intake passage of the internal combustion engine, a motor coupled via a power transmission mechanism to the throttle shaft for driving the throttle valve in a closing direction and an opening direction to adjust the amount of opening of the throttle valve, and a cover connected to the throttle body and enclosing the power transmission mechanism. The cover includes a built-in throttle sensor for determining the amount of opening of the throttle valve. A connecting member connects the throttle sensor and the throttle shaft. 
     According to the present invention, the cover forms the body of the throttle sensor and only one portion is required for connecting the cover to the throttle body. This advantageously decreases the number of parts, thereby reducing the production cost of the throttle control device and simplifying the assembly. In addition, the concentration or integration of parts brings about a reduction in the overall size of the throttle control device. 
     The present invention also provides an integral connecting portion on the cover which is provided with terminals to be electrically coupled to the motor and the throttle sensor, respectively. The electric coupling operations to the throttle control device are thus significantly improved, thereby facilitating or making easier the mounting operation of the throttle valve control device on the internal combustion engine. 
     Also, according to the present invention, the throttle sensor includes a sensor shaft journaled in the cover and biased toward a direction of closing the throttle valve, the sensor shaft is fixed with the connecting member in order that the connecting member is engagible with a projection formed at an end of the throttle shaft in the direction of closing the throttle valve, and a guide member is provided at either the connecting member or the projection for rotating the sensor shaft in the direction of opening the throttle valve when the cover is mounted to the throttle body. The guide portion allows the connecting member to engage the throttle shaft in the direction of closing throttle valve and this ensures a reliable transmission of rotation from the throttle shaft to the sensor shaft without rattling, thereby deriving a voltage signal from the throttle sensor which is in response to the opening amount of the throttle valve. Moreover, in the event the sensor shaft fails to rotate, the throttle sensor issues a higher voltage signal than a voltage signal indicative of the actual opening amount of the throttle valve, with the result that the motor is driven in the direction of closing the throttle valve so as to decrease the voltage signal from the throttle sensor. Thus, the output power of the internal combustion engine is decreased, thereby ensuring vehicle safety. 
     According to another aspect of the invention, a throttle control device includes a throttle body, a throttle shaft journalled on the throttle body, a throttle valve accommodated in the throttle body and mounted on the throttle shaft for adjusting the amount of air passing through the intake passage of the internal combustion engine, a motor coupled via a power transmission mechanism to the throttle shaft for driving the throttle valve in a closing direction and an opening direction to adjust the amount of opening of the throttle valve, and a cover secured to the throttle body to enclose the power transmission mechanism. A throttle sensor is mounted on the cover so that connecting the cover to the throttle body results in mounting of the throttle sensor on the throttle. The throttle sensor is operatively connected to the throttle shaft body for determining the amount of opening of the throttle valve. 
     In accordance with another aspect of the invention, a throttle control device for a vehicle includes a throttle body, a throttle shaft journalled on the throttle body, a throttle valve accommodated in the throttle body and mounted on the throttle shaft for adjusting the amount of air passing through the intake passage of the internal combustion engine, a motor coupled via a power transmission mechanism to the throttle shaft for driving the throttle valve in a closing direction and an opening direction to adjust the amount of opening of the throttle valve, and a cover connected to the throttle body to enclose the power transmission mechanism. A throttle sensor is operatively connected to the throttle shaft for determining the amount of opening of the throttle valve. The cover includes an integrally formed connecting portion at which are exposed a plurality of terminals that are electrically connected to the motor and the throttle sensor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     The foregoing and additional features of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawing figures in which like elements are designated by like reference numerals and wherein: 
     FIG. 1 is a cross-sectional view of a throttle control device in accordance with an embodiment of the present invention; 
     FIG. 2 is a side view of the throttle control device shown in FIG. 1 in which the throttle body cover has been removed; 
     FIG. 3 is a rear view of the throttle body cover employed in the throttle control device shown in FIG. 1; 
     FIG. 4 is a side view showing the relationship between the lever of the throttle sensor and the projection of the final gear when the throttle body cover is coupled to the throttle body; 
     FIG. 5 is an enlarged cross-sectional view of the throttle body cover; 
     FIG. 6 is a front view of the throttle body cover; and 
     FIG. 7 is a plan view of the substrate employed in the throttle control device in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to FIG. 1, a throttle control device in accordance with the present invention includes a throttle body  10  formed of aluminum so as to be lightweight while also possessing excellent heat radiation properties. The throttle body  10  is formed with four holes  10   a  through which respective bolts extend for mounting the throttle body  10  on the intake manifold of an internal combustion engine. The throttle body  10  is provided with an intake passage  10   b  in which an annular-shaped or disk-shaped throttle valve  11  is provided. The throttle valve  11  is positioned in an axial slit that is formed in a throttle shaft  12 . The throttle valve  11  is fixed to the throttle shaft  12  by two screws  13 ,  13  to produce an integrated construction of the throttle valve  11  and the throttle shaft  12 . The throttle shaft  12  includes opposite end portions and each of these end portions of the throttle shaft  12  is journalled in the throttle body  10  via a respective bearing  14 ,  15 . A water passage is also formed in the throttle body  10  through which cooling water passes for cooling the throttle body  10  and the internal combustion engine. 
     A retainer  17  is fixed at the extreme right end of the throttle shaft  12  by a nut  16 . The retainer  17  is engaged by one end of a return spring  18  while the opposite end of the spring  18  engages the throttle body  10 . The return spring  18  continually urges the throttle valve  11  into its closing position. A bearing  19  and a sector or final gear  22  are fixedly mounted on the left end of the throttle shaft  12  so that no relative movement occurs therebetween. A retainer  20  is fixedly mounted on the outer race of the bearing  19 . The retainer  20  is adapted to engage the final gear  22  when the throttle valve  11  is driven in its opening direction. 
     One end of an opener spring  21  engages the retainer  20  and the opposite end of the opener spring  21  engages the throttle body  10 . The opener spring  21  applies an urging force which acts on the throttle valve  11  by way of the retainer  20  and the final gear  22  for continually urging the throttle valve  11  in its opening direction by overcoming the urging force of the return spring  18 . 
     The retainer  20  possesses a projection  20   a . As seen with reference to FIG. 2, the projection  20   a  engages a default opening degree adjusting screw  25  which is provided in the throttle body  10 . This screw  25  mechanically establishes a default opening degree θ, as will be described in more detail below, even when a motor  30  is inactive. As mentioned above, because the retainer  20  engages the final gear  22  in the direction of opening the valve  11 , when the projection  20   a  is, at its default position, in engagement with the screw  25 , if the motor  30  is activated for concurrent rotation of the final gear  22  and the throttle valve  11  in the direction of opening the throttle valve  11 , the final gear  22  is brought into rotation relative to the retainer  20 . On the other hand, if the motor  30  is activated for concurrent rotation of the final gear  22  and the throttle valve  11  in the direction of closing the throttle valve  11 , the final gear  22  is brought into rotation together with the retainer  20 . 
     A fully-closing angle adjusting screw  26  is also provided in the valve body  10 . When the final gear  22  is brought into engagement with fully-closing angle adjusting screw  26 , the throttle valve  11  assumes its full closing position at which the passage  10   b  is fully closed. 
     A mounting bore  10   c  is formed in the throttle body  10  and is disposed perpendicular to the intake passage  10   b . The motor  30  is accommodated in the mounting bore  10   c . The motor  30  includes a housing  31  formed of a magnetic material which acts as a yoke. The housing is in the form of a cylinder with one end closed and the other opened. The housing  31  is fitted in the mounting bore  10   c  and the open end of the housing  31  is connected via a first plate  32  to a second plate  33  that is fixed to the throttle body  10  by a screw mechanism. The housing  31  is thus immovable or fixed in the mounting bore  10   a  of the throttle valve  10 . 
     A shaft  36  is positioned in the housing  31  and includes opposite ends (i.e., a right end and a left end) that are rotatably supported by respective axially spaced bearings  34 ,  35 . The left end bearing  34  is fixed to the first plate  32  and the right end bearing  35  is fixed to the closed end or bottom of the housing  31 . A rotor  37  is fixedly mounted on the shaft  36 . The rotor  37  is in the form of a plurality of stacked annular-shaped thin plates made of magnetic material. A cylindrically-shaped magnet  39  is adhered to the inner surface of the housing  31 . The rotor shaft  36  is in slidable contact with a brush mechanism connected to the housing  31  via a holder. The brush mechanism is connected to connecting terminals  43   a ,  43   b , as will be described below in more detail, which are accommodated in a casing  41 . A commutator  40  is also located within the housing  31  in surrounding relation to the shaft  36 . 
     As shown in FIGS. 1 and 2, a pinion gear  42  is fixedly mounted on the end of the rotor shaft  36  extending from the open end of the housing  31 . The pinion gear  42  is in meshing engagement with a first gear portion  24   b  of a secondary gear  24  which is rotatably mounted on a shaft  23  that is fixed to the throttle body  10 . The secondary gear  24  also has a second gear portion  24   a  of smaller diameter than the first gear portion  24   b . The second gear portion  24   a  is in meshing engagement with the final gear  22 . The pinion gear  42 , the secondary gear  24  and the final gear  22  together constitute a gear train or a power transmission mechanism. 
     A resin-made throttle body cover  50  is connected via a gasket  51  to one side of the throttle body  10  to enclose or cover the gear train or a power transmission mechanism formed by the pinion gear  42 , the secondary gear  24 , and the final gear  22 . As best shown in FIGS. 5 and 6, the throttle body cover  50  accommodates a pair of throttle sensors  60 ,  60 , each of which is adapted to determine or measure the throttle opening amount or the degree of opening of the throttle valve  11 . The outwardly facing side of the throttle body cover  50  is provided with a hollow portion  55  that is covered or closed in a fluid-tight manner by a resin-made plate  71 . The plate  71  is connected to the throttle body  10  by screws. 
     As shown in FIG. 7, the inwardly facing side of the plate  71  which opposes the hollow portion  55  of the throttle body cover  50  is provided with four electrically isolated resistors  73   a ,  73   b ,  74   a ,  74   b  having main or arc-shaped portions that are arranged in a concentric manner. The ends of the resistor  73   a  form terminals  72   a ,  72   b , while the ends of the resistor  74   b  form terminals  72   e ,  72   f . One end of the resistor  73   b  and one end of the resistor  74   a  constitute terminals  72   c ,  72   d , respectively. 
     A sensor shaft  62  is journaled in the throttle body cover  50  via a bushing  61  so that the sensor shaft  62  is coaxial with the throttle shaft  12 . One end of the sensor shaft  62  extend into the hollow portion  55  and the opposite end of the sensor shaft  62  extends into a space in which the aforementioned gear train is accommodated. In the hollow portion  55 , one end of the sensor shaft  62  is fixed with a holder  63  that holds a pair of brushes  67 ,  68 . The brushes  67 ,  68  possess forked or bifurcated configurations. Each of the forked or bifurcated configurations has a first contact portion and a second contact portion which are engagible with the set of resistors  73   a ,  74   b  and the set of resistors  73   b ,  74   a , respectively. As seen in FIG. 5, a return spring  66  is operatively associated with the sensor shaft  62  and continually urges the sensor shaft  62  in the direction of closing of the throttle valve  11 . 
     Six accommodating portions are formed in the hollow portion  55  of the throttle body cover  50  as generally shown in FIGS. 5 and 6. Each accommodating portion extends toward the plate  71  in parallel to the sensor shaft  62  and has an opening exposed to or facing towards the plate  71 . A plurality of coil springs  69   a - 69   f  are also provided and each coil spring is loosely fitted in one of the accommodating portions. The coil springs  69   a - 69   f  are formed of a wire having electric conductivity. 
     As shown in FIGS. 5 and 6, the cover  50  is also outfitted with a plurality of terminals  70   a - 70   f  that are adapted to be operatively associated with respective ones of the coil springs  69   a ,  69   b ,  69   c ,  69   d ,  69   e ,  69   f . When the cover  50  is mounted in place, the coil spring  69   a  is interposed between the terminal  72   a  and a terminal  70   a , the coil spring  69   b  is interposed between the terminal  72   b  and a terminal  70   b , the coil spring  69   c  is interposed between the terminal  72   c  and a terminal  70   c , the coil spring  69   d  is interposed between the terminal  72   d  and a terminal  70   d , the coil spring  69   e  is interposed between the terminal  72   e  and a terminal  70   e , and the coil spring  69   f  is interposed between the terminal  72   f  and a terminal  70   f . The terminals  70   a ,  70   b ,  70   c ,  70   d ,  70   e ,  70   f  extend into the bottoms of the respective accommodating portions that receive the respective coil springs  69   a ,  69   b ,  69   c ,  69   d ,  69   e ,  69   f . Thus, in accordance with the present invention, the terminals  70   a - 70   f  are integral with and form a unitary one-piece construction with the throttle body cover  50  so that the terminals  70   a - 70   f  make connection with the respective coils springs  69   a ,  69   b ,  69   c ,  69   d ,  69   e ,  69   f  upon mounting the throttle body cover  50  in place on the throttle body  10 . 
     As illustrated in FIG. 1, the throttle body cover  50  is provided with an integral socket-like connector portion  56  for effecting connection with a controller  80 . The connector portion  56  is thus integral with and formed in one piece as a unitary structure with the throttle body. As seen with reference to FIG. 6, the terminals  70   a - 70   f  are accommodated or exposed in the connector portion  56 . The connector portion  56  is formed with a passage  52  which connects the connector portion  56  and the space in which is accommodated the gear train. As shown in FIG. 1, the case  41  which accommodates the terminals  43   a ,  43   b  of the motor  30  is fitted in the passage  52 . 
     When the throttle body cover  50  is mounted onto the throttle body  10 , the set of terminals  43   a ,  43   b , as well as the terminals of the throttle sensors, are accommodated in the connector portion  56 . It is to be noted that the distal end of each of the terminals  43   a ,  43   b  is the same as that of each of the terminals  70   a - 70   f . 
     The terminals  70   b ,  70   f  are fed with electric power via the controller  80 , while terminals  70   a ,  70   e  are grounded. This allows voltage signals to be issued from the terminals  70   c ,  70   d  which are of different directions and which vary in magnitude in response to rotation of the sensor shaft  62 . Of course, it is possible, by changing the grounded terminals, to issue the same voltage signals from the terminals  70   c ,  70   d . 
     As shown in FIGS. 3 and 5, a lever  65  acting as a connecting member is secured to the end of the sensor shaft  62  which extends into the space in which the gear train, including the final gear  22 , is located. The lever  65  has a first projection  65   a  which extends in the radial direction with respect to the sensor shaft  62  and a second projection  65   b . The second projection  65   b  extends with respect to the sensor shaft  62  in a direction opposite to the first projection  65   a , and then bends so as to extend parallel to the sensor shaft  62 . For regulating a fully closed position and a fully opened position of the throttle sensor  60 , the first projection  65   a  of the lever  65  is engagible with one of two angularly spaced or rotationally displaced stoppers in response to the angular position or rotational angle of the sensor shaft  62 . The two stoppers include a full-close stopper  53  and a full-open stopper  54  which are formed on the throttle body cover  50  so as to be exposed to or face the space in which is accommodated the gear train that includes the final gear  22 . 
     Prior to the connection of the throttle body cover  50  to the throttle body  10 , the first projection  65   a  of the lever  65  is in engagement with the full-close stopper  53  as depicted in the full line outline in FIG. 3 due to the fact that the sensor shaft  62  is urged in the direction of closing of the throttle valve  11  by the return spring  66 . The position regulated by the full close stopper  53  is nearer to the fully closed position of the throttle valve  11  than the position regulated by the screw, while the position regulated by the full open stopper  54  is nearer to the fully opened position of the throttle valve  11  than the position regulated by an engagement of the retainer with the throttle body  10 . 
     As shown in FIGS. 3 and 4, the distal end or free end portion of the second projection  65   b  of the lever  65  is configured to form a bent guide portion  65   c . At the default position as previously explained, a projection  22   a  formed as an integral extension of the final gear  22  extends toward the guide portion  65   c  in parallel to the sensor shaft  62 . The bent guide portion  65   c  of the lever  65  has a slanted surface and when the projection  22   a  of the final gear  22  is brought into engagement with the guide portion  65   c  of the lever  65  under a force, the resultant component force urges or applies a force to the slant or bent portion  65   c  of the lever  65 , thus causing rotation of the guide portion. Thus, in the course of fixing the throttle body cover  50  to the throttle body  10 , when the projection portion  22   a  of the final gear  22  is urged onto the slant or bent guide portion  65   a  of the lever  65  while inserting the case  41  into the mounting bore  52 , as can be seen from FIGS. 3 and 4, the lever  65  is rotated through the angle θ from the fully closed position, thereby engaging the second projection  65   b  of the lever  65  with the projection  22   a  toward the fully closed position. Thus, the sensor shaft  62  is rotated through an angle between the fully closed and opened positions thereof, depending on the angular position of the final gear  22 . The result is that the voltage signals from the respective terminals  70   c ,  70   d  are derived and are in proportion to the opening amount of the throttle valve  11 . 
     In the foregoing structure, when the acceleration pedal is depressed, the amount or degree of acceleration corresponding to the amount of depression of the acceleration pedal is determined by an acceleration sensor  81 , with a signal being fed from the sensor to the controller  80 . Depending on such signal, current is supplied via the controller  80  to the motor  30 , which causes an initiation of the motor  30 , thereby operating the throttle valve  11  to adjust the amount of intake air passing through the intake passage  10   b  formed in the throttle body  10 . At this time, the controller  80  controls the motor  30  under feedback or PID control in such a manner that the actual opening amount of the throttle valve  11  which is indicated by the signal from the throttle sensor  60  is compared to a target opening amount of the throttle valve  11  which is indicated by the signal from the acceleration sensor  81  to calculate a deviation between the two signals, and with the deviation converging to zero. 
     As previously explained, the throttle sensors  60  are accommodated within and secured to the throttle body cover  50 , thus allowing the throttle body cover  50  to be used as the body or mounting mechanism of the throttle sensor  60 . The throttle sensors  60  thus form a built-in part of the throttle body cover  50 . Thus, mounting the throttle body cover  50  on the throttle body  10  in a fixing manner includes the concurrent mounting of the sensors  60  in the throttle body  10 . This advantageously eliminates screws and the like previously required for proper mounting of each of the throttle sensor body and the throttle sensors per se on the throttle body, and decreases the number of parts. The present invention thus allows realization of reduced production costs associated with the throttle control device. In addition, the assembly of the throttle control device is simplified and the size of the throttle control device can be reduced. 
     The terminals for both the throttle sensor  60  and the motor  30  are accommodated in the sole or common connector portion  56  which is integrally formed in the throttle body  50 . This markedly improves the electric coupling operation between the throttle device and the controller  80 , thereby easing or facilitating the mounting operation of the throttle valve control device on the internal combustion engine. 
     The cam action that occurs between the guide portion  65   a  of the lever  65  and the projection  22   a  of the final gear  22  causes rotation of the lever  65  through an angle θ from the stopper position in the valve opening direction, thus ensuring, without disturbing the assembly operation, engagement of the second projection  65   b  of the lever  65  under the bias force of the return spring  66  with the projection  22   a  of the final gear  22  in the valve closing direction. The full-close position of the lever  65  which is regulated by the stopper  53  is offset an angle toward the valve closing side from the full-close position of the throttle valve  11  which is regulated by the screw  26 . The result is that when the throttle valve  11  takes its full-close position no separation is made between the projection  22   a  of the final gear  22  and the second projection  65   b  of the lever  65  even if manufacturing tolerances of the parts fall outside of the allowable ranges. Thus, the rotation of the throttle shaft  12  is reliably transmitted to the sensor shaft  62  without rattling and so the throttle sensor  60  is able to provide a voltage signal that is accurately indicative of the opening amount of the throttle valve  11 . In addition, in the event the sensor shaft  62  does not rotate, the throttle sensor  60  issues a higher signal than a signal indicative of the actual opening amount of throttle opening, thus making the controller  80  drive the motor  30  in the closing direction of the throttle valve  11  for lowering the issued voltage signal from the throttle sensor  60 , and thereby decreasing the output power of the internal combustion engine which improves vehicle safety. 
     The full-open position of the lever  65  which is regulated by the stopper  54  is offset an angle toward the valve open side from the full-open position at which the retainer  17  is in engagement with the throttle body  10 . Until the throttle valve  11  takes its full-close position the first projection  65   a  of the lever  65  is prevented from being in engagement with the full-open stopper  54 . The throttle valve  11  is thus ensured to be driven or transferred to the desired full-open position. 
     Instead of the structure described above in which the guide portion  65   c  is provided on the second projection  65   b  of the lever  65 , it is possible to form such a guide portion on the projection  22   a  of the final gear  22 , or to provide a guide portion on both the projection  22   a  of the final gear  22  and the second projection  65   b  of the lever  65 . 
     The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiment described. Further, the embodiment described herein is to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the invention be embraced thereby.