Control mechanism for engine throttle position

This invention relates to a control mechanism, which is selectively engageable, for engine throttle position and more particularly to a lever mechanism for effecting engagement and disengagement of the control mechanism.

Engine and vehicle speed regulation systems typically include a servo mechanism for positioning the engine throttle in order to achieve a desired speed and a coupling element connected between the servo mechanism and the throttle for selectively engaging and disengaging the control mechanism. When speed regulation is desired, the coupling element is actuated to engage the control mechanism; when speed regulation is not desired or when a malfunction is detected, the coupling element is actuated to disengage the control mechanism.

In one type of speed regulation system, a Bowden cable or the like is attached to the engine throttle, and is positioned by the output shaft of a rotary electric motor through two or more gear (coupling) elements. When the gear elements are in meshing engagement, the electric motor is connected to position the throttle; when the gear elements are moved out of meshing engagement, the electric motor is disconnected from the throttle. An example of a speed regulation system of this type is shown in the U.S. Patent No.4,187,734.

A manufacturing and assembly problem with regulating systems of the type described above, is that unless the various system components are precision formed, their cumulative tolerance variations result in some system-to-system differences of operation. Respecting the coupling elements, it is important to ensure that the gear elements properly mesh or unmesh when it is desired to engage or disengage the control mechanism. As a result, some calibration of the coupling elements is needed if it is decided to forgo the expense of precision formed components.

A control mechanism for engine throttle position in accordance with the present invention is characterised by the features specified in the characterising portion of Claim 1.

This invention is directed to a mechanism for selectively engaging and disengaging a pair of coupling elements in a throttle position control mechanism including integral means for calibrating the control mechanism so as to compensate for manufacturing and assembly tolerances. Essentially, the control mechanism includes a lever mechanism which comprises first and second members angularly displaceable about the axis of a fixed pin. The first. member is mounted so as to pivot about the pin and the second member is mounted to the first member for angular displacement therewith. The second member has a pair of arms extending transverse the axis. One of such arms has an input location formed thereon which is adapted to be displaced by a solenoid actuator to a first angular position with respect to the axis. The other arm has an output location formed thereon adapted to move the coupling elements into and out of meshing engagement, the coupling elements being in proper meshing engagement when the output location has been displaced to a second angular position in respect to the axis.

Integral means are provided for adjusting the mounting of the second member in relation to the first member so as to shift the position of the second member at least radially in respect to the axis such that the output location on the second arm is displaced to the second angular position with respect to the axis when the first arm is displaced by the solenoid actuator to the first angular position. In this way, the lever mechanism is calibrated so that a proper meshing engagement of the coupling elements is achieved when the solenoid actuator displaces the input location of the second member to the first predetermined angular position despite the manufacturing and assembly tolerance variations. The calibration may be performed manually or automatically using a gauge or other position measuring instrument for indicating when the proper calibration has been achieved.

In the illustrated embodiment, the second member includes a stem extending radially with respect to the axis and the first member takes the form of a bifurcated sleeve pivotably mounted on the pin. The first and second members are mounted together by a screw or like fastener threaded into one of the members, and the calibration is effected by turning the screw to adjust the mounting of the second member in relation to the first member along a line substantially radial to the axis.

This invention is now described, by way of example, with reference to the accompanying drawings in which:- <ul id="ul0001" list-style="none"><li>Figure 1 is a top view of a control mechanism, which is electric motor driven, for engine throttle position according to this invention with the cover plate and control circuitry broken away;</li><li>Figures 2 and 3 are cross-sectional views of the control mechanism depicted in Figure 1 along the lines 2-2. Figure 2 depicts the lever mechanism of this invention in a position for engaging the throttle position control, and Figure 3 depicts the lever mechanism in a position for disengaging the throttle position control;</li><li>Figures 4 and 5 are cross-sectional views of the control mechanism taken along lines 4-4 and 5-5 as seen in Figures 2 and 3, respectively. Figure 4 depicts the coupling elements when meshingly engaged by the lever mechanism, and Figure 5 depicts the coupling elements when disengaged by the lever mechanism;</li><li>Figure 6 is a cross-sectional view of the lever mechanism taken along lines 6-6 of Figure 2; and</li><li>Figure 7 is a cross-sectional view of the lever mechanism taken along lines 7-7 of Figure 6.</li></ul>

Referring now more particularly to Figures 1 and 2, a control mechanism 10 is shown for adjusting the position of an engine throttle 12. The various control mechanism 10 components are supported within a housing 14 which is die cast and mounted to a fixed vehicle support member by suitable attachment means at the grommet/flange locations 16. The mechanical connection between the engine throttle 12 and the control mechanism 10 is by way of a Bowden cable 18 or the like, which Bowden cable is supported and retained within the control mechanism 10 by a pulley 20. The pulley 20, in turn, is rotatably supported on an upper shaft 22 which is staked onto a pair of housing supports 24 and 26. As may be best seen in Figures 4 and 5, the pulley 20 is axially retained on the upper shaft 22 by the snap rings 28 and 30. A spiral band spring 32 supported on the inboard end of the pulley 20 is also axially retained by the snap ring 30, the free end of the spiral band spring 32 being retained by a housing lip 34. Spiral band spring 32 is wound so as to exert a releasing force on the pulley 20, which force must be overcome to effect a movement of the engine throttle 12. A face 36 of the pulley 20 has gear teeth 38 formed on its periphery, which gear teeth are engageable with the teeth of a further gear element, as will later be described. A knob 39 integral with an outboard pulley face 40 contacts the opposing sides of housing flange 41 as shown in Figures 2 and 3 to limit the rotation of the pulley 20.

A lower shaft 42 is supported within the housing 14 beneath the upper shaft 22, and rotatably supports a sleeve member 43 having geared surfaces 44 and 46 at opposite ends thereof. The lower shaft 42 is supported in the housing 14 at one end thereof by a ball sleeve 48 which rests in a housing pocket 50. The other end of the lower shaft 42 is supported by a lever mechanism 72 of this invention which operates, as will later be described, to selectively raise and lower such end of the lower shaft 42 to selectively engage and disengage the gear teeth 38 and geared surface 44. Figures 2 and 4 depict the lower shaft 42 in the raised position engaging the gear teeth 38 and geared surface 44 while Figures 3 and 5 depict the lower shaft 42 in the lowered position disengaging the gear teeth 38 and geared surface 44. Gear teeth 38 and geared surface 44 define the coupling elements of the control mechanism 10.

The geared surface 46 of the sleeve member 43 is of the worm gear variety and continuously meshes with a complementary worm gear 52 formed on the rotor shaft 54 of an electric stepper motor 56. The rotor shaft 54 is supported at each end thereof in the housing 14 by bearings 58 and 60 which seat in housing pockets 62 and 64. The motor stator 66 rests within the housing 14 and is retained by a plate 68, which in turn, is secured to the housing 14 by fasteners 70. The lever mechanism 72 of this invention, which operates as indicated above to raise and lower the lower shaft 42 to engage and disengage the gear teeth 38 and geared surface 44, is best seen in the Figures 6 and 7. Essentially, the lever mechanism 72 comprises a pin 74, a first member 76 pivotably supported on pin 74, and a second member 78 mounted on the first member 76 by threaded fastener means in the form of a screw fastener 80. The pin 74 is staked onto a housing support 82, and passes through similar diameter openings in bifurcated arms 83 and 84 (which define lateral spaced extensions) of the first member 76 so that the first member 76 is angularly displaceable about the axis 86 of the pin 74. The second member 78 of the lever mechanism 72 is best seen in the section of Figure 7 and includes a tapped stem 90 for receiving the threads of the screw fastener 80, and a pair of arms 92 and 94 extending transverse to the axis 86 of the pin 74. The arm 92 has formed thereon an input location 96 for receiving a mechanical input from a solenoid actuator 98, as will later be described, and the arm 94 has an output location 100 formed thereon for receiving and supporting the lower shaft 42, as indicated above. Solenoid actuator 98 therefore defines input means for the lever mechanism 72, and lower shaft 42 defines output means for the lever mechanism. The head of screw fastener 80 is seated on the upper surface of the first member 76 and a spring 102 (which defines resilient means) separates the first and second members 76 and 78 to tension the parts as an aid in their assembly. A spring 104 operates on the arm 92 of second member 78 and biases the second member 78 toward the position depicted in Figures 3 and 5, disengaging the gear teeth 38 and geared surface 44.

The solenoid actuator 98 is supported within the housing 14 by straps 110 and 112 and fasteners 114 and 116, as best seen in Figures 1-3. The magnetic circuit of the solenoid actuator 98 includes stationary arms 118 and 120 and a movable arm 122. The movable arm 122 hinges on the stationary arm 118 and is movable between its normally open position as depicted in Figure 3 and its closed position as depicted in Figure 2. The movable arm 122 is in constant contact with the input location 96 of the lever mechanism 72 and serves to angularly displace the second member 78 about the axis 86 of pin 74 to selectively engage and disengage the gear teeth 38 and geared surface 44. When the movable arm 122 is in the normally open position, as shown in Figure 3 and as urged by the spring 104, the output location 100 of the arm 94 is displaced to an angular position in respect to the axis 86 of the pin 74 for which the gear teeth 38 and geared surface 44 are disengaged. When the movable arm 122 is in its closed position, as depicted in Figure 2 by the operation of the solenoid actuator 98, the output location 100 of the arm 94 is displaced to an angular position in respect to the axis 86 of pin 74 for which the gear teeth 38 and geared surface 44 are meshingly engaged. The movable arm 122 is moved from its normally open position to its closed position through energization of the solenoid actuator coil 123 with electrical current. Such energization produces an attractive force between the movable arm 122 and the stationary arm 120, such force increasing in magnitude as the arms 120 and 122 near. A leaf spring 124 mounted on the movable arm 122 contacts the stationary arm 120 as the arms 120 and 122 approach contact and serves to lessen the net attractive force between the arms so that upon de-energization of the solenoid actuator coil 123, the movable arm 122 will be urged toward its normally open position.

The electrical leads for energizing the windings of the electric stepper motor 56 and the solenoid actuator coil 123 are attached to the female connector block 130. A printed circuit board 132 supports the circuitry for energizing the electric stepper motor 56 and solenoid actuator coil 123 and is supported on a housing cover 134 via connectors 136. The housing cover 134 in turn is secured to the housing 14 via fasteners 138. The printed circuit board 132 has mounted thereon a male connector strip 140 which mates with the female connector block 130 for providing electrical connections between the control circuitry mounted on the printed circuit board 132 and the electric stepper motor 56 and solenoid actuator 98 mounted in the housing 14. Electrical power and control signals for the circuitry on the printed circuit board 132 are fed through the housing cover 134 through an opening 142.

When regulation of the engine throttle 12 is desired, the solenoid actuator coil 123 is energized to displace the input location 96 of lever mechanism 72 as shown in Figures 2, 4 and 7 for engaging the teeth of gear teeth 38 and geared surface 44. Thereafter, the windings of electric stepper motor 56 are suitably energized with electric current through the printed circuit board components and the female connector block 130 and male connector strip 140, and the rotation of the rotor shaft 54 operates to move the engine throttle 12 through the geared surface 46, worm gear 52 and gear teeth 38, geared surface 44. When regulation of the engine throttle 12 is no longer desired or when a system malfunction is sensed, the solenoid actuator coil 123 is deenergized, and the leaf spring 124 and spring 104 displace the input location 96 of lever mechanism 72 as shown in Figures 3 and 5 for disengaging the teeth of gear teeth 38 and geared surface 44. At such point, the rotor shaft 54 of electric stepper motor 56 is decoupled from the pulley 20, and the spring 32 rotates the pulley 20 to the released position as seen in Figure 3 to release the tension on Bowden cable 18.

At a predefined point in the assembly of the control mechanism 10, the operation of the lever mechanism is calibrated for manufacturing and assembly tolerances through an adjustment of the screw fastener 80. As indicated above, adjustment of the screw fastener 80 results in an adjustment of the mounting of the second member 78 in relation to the first member 76 so as to shift the position of the second member 78 at least radially in respect to the axis 86 of pin 74. The screw fastener 80 therefore defines an adjusting means for the lever mechanism 72. This operation serves to alter the relative displacement angle of the arms 92 and 94 in respect to the axis 86 so as to adjust the angular position of the output location 100 for a given angular location of the input location 96. The object is to ensure that when the movable arm 122 of solenoid actuator 98 is in its normally open position, the gear teeth 38 and geared surface 44 are disengaged, and also to ensure that when the movable arm 122 is in its normally closed position, the gear teeth 38 and geared surface 44 are properly meshed, it being understood that normal manufacturing and assembly tolerances produces some variation in operation from control mechanism to control mechanism. Although the calibration process may be performed manually or automatically in a number of ways, it is preferably performed in an automatic fashion by energizing the solenoid actuator coil 123 and effecting an adjustment of the screw fastener 80 until a gauge or like instrument detects that the output location 100 of arm 94 is positioned so as to effect proper meshing engagement of the gear teeth 38 and geared surface 44. In this regard, it will be understood that the calibration procedure may be performed when the control mechanism 10 is only partially assembled-that is, prior to the mounting of upper shaft 22 and pulley 20 in the housing 14. When the lever mechanism 72 is properly calibrated in this manner, the travel afforded by the movement of the movable arm 122 of solenoid actuator 98 is sufficient to ensure that the gear teeth 38 and geared surface 44 are completely disengaged upon de-energization of the solenoid actuator coil 123. The layout of the various control mechanism 10 components within the housing 14 permits ease of assembly in that each of the components may be inserted and secured from the top side of the housing 14 as seen in Figure 1. Moreover, the calibration of lever mechanism 72 is also performed from the top side of housing 14. Following assembly and calibration of the various control mechanism 10 components, the housing cover 134 and printed circuit board 132 are mounted on the housing 14, thereby mating the female connector block 130 and male connector strip 140 to electrically connect the control circuitry to the electric stepper motor 56 and solenoid actuator coil 123, and completing the control mechanism assembly.