Abstract:
The present invention relates to a control apparatus for a throttle stop. The control apparatus provides accurate and consistent throttle stop operation.

Description:
BACKGROUND OF THE INVENTION 
   A drag race is a race between two racing vehicles (typically cars or motorcycles) from a standing start to a finish line that is up to a quarter mile away down a straight race track. A drag race is started by a vertical series of lights, called a “Christmas tree,” that sequentially light yellow lights followed by a green light that starts the race. The objective of a drag race is to reach the finish line in less time, after the green light starts the race, than does the opponent. The time to reach the finish line is the total of two parts of the race: the length of time between the green light signaling that the race has started and the vehicle leaving the starting line (commonly referred to as the Reaction Time), and the time between leaving the starting line to reaching the finish line (commonly referred to as the Elapsed Time or ET). Electronic timers measure both the Reaction Time and ET. 
   Some types of drag racing limit the cars to a selected ET. In those races, examples of which are referred to as “Bracket Racing” or “Super Class Racing”, the driver, the race track, or the race sanctioning association selects the ET that the car should run. This is known in racing as the Dial In. The object of a drag race in which the cars each have a Dial In is for the car to reach the finish line ahead of the opponent and do so with an ET that is equal to or larger than the Dial In. If the racer goes quicker than his Dial In and his opponent does not, then his opponent wins the race. If both racers go quicker than their Dial Ins, the racer who goes furthest under his Dial In is disqualified and his opponent wins. 
   In Super Class racing, both cars are assigned the same Dial In and therefore, both cars leave the starting line at the same time. They race each other and try to finish first without going quicker than the assigned Dial In. 
   In other ET or Bracket racing, a slow car can race a fast car by having the race track handicap the fast car by permitting the slower car to start the race first. This is done using a Christmas Tree that has a series of lights for each car. The Christmas Tree lights for the slower car are lighted a selected amount of time before the lights for the faster car. Handicapping allows the slower car to start first by an amount of time that is equal to the difference between the Dial Ins of the two cars (the handicap). In theory, if both cars leave the starting line exactly when their respective green Christmas tree lights turn on, and they run perfectly on their Dial In, they should cross the finish line at the same time. 
   The purpose of this type of racing is to minimize the cost of campaigning a race car. A car that competes in Super Class or ET racing need not be at its performance limit to compete. Cars are built to reliably perform well enough to complete the race at the Dial In. In the Super Classes, where the Dial In is assigned by the track or the race sanctioning body, and in other ET racing, the race car engines produce enough power so that the car can run quicker than the Dial In under track or weather conditions that cause a car to run slower than normal. A car having more power than required to run its Dial In can always run too quickly under normal conditions and so it must be slowed down to avoid disqualification for running under its Dial In. 
   Devices known as “throttle stops” were created to selectively limit the power of race car engines to prevent the car from completing the race with an ET that is less than its Dial In. A throttle stop adjustably controls the engine throttle to set the engine power level up or down to allow the car to run at exactly the Dial In regardless of the track or weather conditions. An additional benefit of using a throttle stop is that it can be turned on and off (changed from limited or throttle stopped power to full power) as the car goes down the track. This usually results in a car having a higher speed at the end of the track than would normally be expected for a car that runs the selected Dial In. This is a particular advantage for a faster car that is chasing a slower car because the faster car driver can judge both how fast he is closing in on the slower car and when he will cross the finish line, and can decide whether to release a throttle stop to increase the car&#39;s speed. The slower car driver must continually look over his shoulder to see the faster car coming up behind him and then he must turn around to look at the finish line. These advantages of “throttle stops” have made them widely used and well known. 
   There are various types of throttle stops, including a “linkage style” throttle stop and a “baseplate style” throttle stop. 
   A linkage style throttle stop (see, for example, Dedenbear Products, Inc. catalog, volume 9, page 19 model TS-10) includes a collapsible link that is part of the throttle linkage between the gas pedal and the engine&#39;s fuel metering device (carburetor or fuel injector). The length of the collapsible link changes thereby changing the position of the butterflies on the fuel metering device to either a more closed position to limit the amount of air flow and engine power or to a more open position to increase engine power. This style throttle stop is inexpensive and easily adaptable to many types of fuel metering devices. A disadvantage of the linkage style throttle stop is that most racing fuel metering devices do not perform well under partial throttle conditions and therefore the car&#39;s performance becomes erratic. 
   Another type of throttle stop is the baseplate style. In this throttle stop, a baseplate is mounted under the fuel metering device. The baseplate has openings through which air and fuel from the fuel metering device enter the engine. Conventional baseplate throttle stops have a set of butterflies mounted in the baseplate openings. The baseplate butterflies open and close to control the total air/fuel mixture flow into the engine after the fuel has been injected into the airstream by the fuel metering device. The advantage of this type of throttle stop is that at all times during a race, the fuel metering device runs at its optimum condition of its wide open position so that the fuel metering and therefore the car performance stays very consistent. This style of throttle stop was created in 1987 by Dedenbear Products, Inc. and has been used to win many World drag racing championships (see Dedenbear Products, Inc. catalog, volume 9, pages 16-17 models TS-1 and TS-5). 
   An improvement of baseplate style throttle stops that is best described as a “disc” style stop is disclosed by U.S. Pat. No. 6,189,505, which is incorporated herein by reference. This throttle stop has, in one embodiment, two counter rotating discs that are stacked on top of each other. Each disc has holes that match the bores of a fuel metering device. As the discs are rotated toward the closed condition, the holes start to overlap and block each other, which chokes off the air/fuel flow. Rotating the discs to the fully open position results in substantially perfect open bores (holes) that match the fuel metering device bores. In this position, there is substantially no restriction to air/fuel flow so maximum engine horsepower is achieved. 
   All types of throttle stops require an actuator to activate the throttle stop mechanism. Actuators have typically been an electric solenoid or a pneumatic cylinder that move the throttle stop mechanisms. 
   Electric solenoids are desirable because they are very simple, reliable, and inexpensive. The drawback to using an electric solenoid is that it opens and shuts instantaneously. On a car with a high horsepower engine, opening and shutting the throttle stop quickly can often cause the car&#39;s rear drive tires to spin (lose traction) due to the abrupt change in the engine power level and driving becomes dangerous. 
   Because of this problem, pneumatic actuators are often used. Adjustable flow limiters in the air supply lines to a pneumatic actuator regulate the speed that the pneumatic actuator moves and therefore how fast the throttle stop opens and closes. By setting the speed that the stop opens and closes, a smooth transition from full power to limited power and vice versa results and the car remains stable as it goes down the track. 
   A disadvantage of both pneumatic and solenoid actuators is that they tend to open and close at the same speed for their entire stroke. For solenoids that speed is undesirably fast. For pneumatic actuators that speed is not always the same for different strokes, as the rate of actuation can change due to supply pressure or temperature variation. 
   SUMMARY 
   In one aspect, the invention features a throttle stop comprising a throttle stop element configured and arranged to be movable between a full open position and at least one flow restricting position to regulate the power of an engine by controlling the flow rate from an air-fuel metering device to the engine. The throttle stop includes an electric motor mounted to the throttle stop element. The motor is configured to move the throttle stop element a characteristic amount upon receiving an electrical signal in a direction that is determined by the electrical signal such that the throttle stop element is moveable between the full open position and the at least one flow restricting position. 
   Various implementations of the invention may include one or more of the following features. The throttle stop includes a feedback mechanism configured to determine the position of the throttle stop element. The feedback mechanism is an encoder, a linear potentiometer, or a linear variable displacement transducer. The electric motor is a stepper motor. A programmable controller is configured to control the operation of the electric motor. An open switch is configured to provide an indication that the throttle stop element is at the full open position. The throttle stop element is a throttle linkage member, a set of butterflies, or counter rotating discs. 
   In another aspect, the invention features a controllable throttle stop. The controllable throttle stop includes a mounting section constructed to engage a throttle linkage element. An electric motor is mounted to the mounting section. The motor is configured to move upon receiving an electrical signal in a direction that is determined by the electrical signal. An extendable link extends away from the motor. The motor is coupled to the extendable link to move the extendable link away from the mounting section in one direction and to move the extendable link toward the mounting section in another direction whereby the motor lengthens and shortens the throttle stop. 
   Various implementations of the invention may include one or more of the following features. The electric motor is a stepper motor. The stepper motor is configured to rotate in two opposite rotational directions and to rotate at characteristic amount upon receiving an electrical pulse. The stepper motor is configured to move the extendable link away from the mounting section upon rotation of the stepper motor in one rotational direction and to move the extendable link toward the mounting section upon rotation of the stepper motor in the other rotational direction. The extendable link is threaded at an end and the stepper motor includes a collar that engages the threaded end to move along the threaded end as the collar is rotated. A controller is operatively connected to the stepper motor. The controller is configured to provide electrical pulses to the stepper motor to cause the stepper motor to rotate. The controller is programmable to cause the stepper motor to cause the extendable link to move a selected distance. The controller is programmable to provide pulses to the stepper motor at a selected rate to specify the length of time during which the extendable link moves. A feedback mechanism is configured to determine the position of the extendable link. 
   In yet another aspect, the invention is directed to a controllable throttle stop including a base plate. The base plate is constructed to be mounted between a fuel metering device and an intake manifold of an internal combustion engine. The base plate has passages through which air and fuel flow from the fuel metering device into the internal combustion engine. The throttle plates are movably mounted to the base plate to selectively interfere with flow through the passages. A throttle plate mechanism is configured to engage the throttle plates to selectively move the throttle plates between a closed position that interferes with flow through the passages and an open position that permits at least substantially unimpeded flow through the passages. An electrical motor driven actuator is operatively coupled to the throttle plate mechanism to move the throttle plates to a more open position in one direction and to a more closed position in another direction to thereby selectively position the throttle plates. 
   Various implementations of the invention may include one or more of the following features. The actuator is a stepper motor coupled to the throttle plate mechanism. The stepper motor is configured to rotate in two opposite rotational directions and to rotate a characteristic amount upon receiving an electrical pulse. The stepper motor is coupled to the throttle plate mechanism to move the throttle plates to a more open position upon rotation of the stepper motor in one rotational direction and to move the throttle plates to a more closed position upon rotation of the stepper motor in the other rotational direction. A controller is operatively connected to the stepper motor. The controller is configured to provide electrical pulses to the stepper motor to cause the stepper motor to rotate to move the throttle plates a selected amount. The throttle plates are butterflies or counter rotating disks mounted in the passages. A feedback mechanism is configured to determine the position of the throttle plates. 
   In still another aspect, the invention is directed to a throttle stop apparatus to regulate the power of an internal combustion engine. The throttle stop apparatus includes a body mounted in the flow path between an air-ftiel metering device and intake valves of the engine. At least a first plate and a second plate are located within the body. The first and second plates are moveable between a full open position and at least one flow restricting position to selectively regulate the power of the engine by controlling flow from the air-fuel metering device to the intake valves of the engine. Each of the first and second plates have an opening with a configuration and dimension sufficient to create substantially no restriction to the flow in the full open position. An electric motor driven actuator is coupled to the first and second plates to move at least one plate relative to another to provide full alignment of the openings in the full open position at wide open throttle conditions of the engine and to provide at least partial restriction to the flow at the at least one flow restricting position. 
   The invention can include one or more of the following advantages. It provides a significant improvement in consistency and accuracy of throttle stop actuation. It enables a throttle stop to open or close a precise known amount, with various adjustments being possible. An electronic control module may be used for automatic positioning. A microprocessor control module may be programmed to control movement time, rate of actuator change, and direction (open and close). A control module may also have feedback capabilities to monitor a variety of data, such as engine revolutions per minute (rpm), weather conditions, engine exhaust temperatures, and engine loads. 
   The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects and advantages will be apparent from the description and drawings, and from the claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic side view of a linkage-type throttle stop actuator according to the present invention. 
       FIG. 2  is a partial cutaway schematic side view of a throttle stop actuator according to the present invention for a butterfly-type baseplate throttle stop. 
       FIG. 3  is a partial cutaway schematic side view of another throttle stop actuator according to the present invention for a butterfly-type baseplate throttle stop. 
       FIG. 4  is a partial cutaway schematic side view of the throttle stop actuator as shown by  FIG. 2  with linkage position indicating apparatus. 
       FIG. 5  is a partial cutaway schematic side view of the throttle stop actuator as shown by  FIG. 2  with a position indicating encoder. 
       FIG. 6  is a partial cutaway schematic side view of the throttle stop actuator as shown by  FIG. 2  with a linear position indicating device. 
       FIG. 7A  is a schematic side elevation view of a linear throttle stop actuator for a disc style throttle stop according to the present invention, and  FIG. 7B  is a schematic top view of the linear throttle stop actuator for the disc style throttle stop. 
       FIG. 8  is a schematic top view of a gear driven throttle stop actuator and disc style throttle stop according to the present invention. 
       FIG. 9  is a schematic diagram of a control system for a throttle stop actuator according to the present invention. 
       FIG. 10  is a schematic diagram of a control system for a throttle stop actuator according to the present invention having feedback connections to the throttle stop. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a throttle stop  10  according to the present invention that controls the opening of a fuel metering device  12 . The fuel metering device  12  is a conventional fuel metering device, such as a carburetor or fuel injector throttle body, having conventional throttle butterflies (not shown). The fuel metering device  12  has a throttle lever or arm  14  that operates the throttle butterflies. A throttle linkage member  16  engages the throttle arm  14  at an end  18  of the throttle linkage member  16 . A threaded section  22  is at an end of the throttle linkage member  16  opposite the end  18 . The throttle stop  10  has a mounting section  26  that engages a throttle rod  28  to mount a stepper motor  24  to the throttle rod  28 . The throttle rod  28  is part of a throttle control mechanism that moves in response to a driver&#39;s actuation of a throttle control, typically a pedal. The throttle rod  28  moves toward and away from the throttle lever  14  to move the throttle lever  14 . Those skilled in the art will recognize that mechanical elements other than a rod, such as a cable, will function as does throttle rod  28 . 
   Movement of the throttle rod  28  is transferred to the throttle lever  14  by movement of the linkage style throttle stop  10  and the throttle linkage member  16 . The throttle stop  10  engages the threaded section  22  of the throttle linkage member  16 . Specifically, the stepper motor  24  is coupled to and rotates a collar (not shown) that engages the threaded section  22  of the throttle linkage member  16 . The collar may be part of a rotor of the stepper motor, or it may be a separate part that is attached to the rotor. Rotating the stepper motor collar that engages the threaded section  22  causes the collar to move along the threaded section  22  thereby moving the stepper motor  24  and mounting section  26  along the throttle linkage member  16 . 
   A stepper motor is a type of an electrical motor that has magnets and coils arranged in such a way that when a direction signal and an electrical pulse are applied to the motor, from a stepper motor controller, the motor collar rotates a precise amount in a given direction. Specifically, each time a pulse is applied to the coil windings, the stepper motor collar rotates a precise angular amount, typically in the range of 1.8 to 7.5 degrees. For example, if a 7.5 degree stepper motor is pulsed 10 times, the motor rotor will rotate exactly 75 degrees. Thus, the throttle stop will open or close a precise known amount for each step pulse that the stepper motor receives. 
   The stepper motor is driven at a rate that is set by the stepper motor controller. The higher the rate, the faster the throttle stop opens. A time setting at which the throttle stop starts and stops is an optional feature. The controller is most typically started when it receives a trigger signal, most typically, a signal from the transmission brake or line lock. Such devices are used to hold a drag race vehicle on the starting line, and when they are released, the vehicle takes off. This is a conventional trigger point. 
   Rotating the stepper motor collar that engages the threaded section  22  causes the member to move along the threaded section thereby moving the stepper motor  24  and mounting section  26  along the throttle linkage member  16 . The collar, as noted, rotates an amount that is characteristic of the motor in response to a pulse and rotates in a rotational direction that is determined by the pulse the stepper motor  24  receives. Rotation of the collar in one direction moves the stepper motor  24  and the mounting section  26  toward the throttle linkage member  16  shortening the throttle stop  10 . Rotation of the collar in the opposite rotational direction moves the stepper motor  24  and the mounting section  26  away from the throttle linkage member  16  lengthening the throttle stop  10 . 
   The throttle stop  10  lengthens (expands) and shortens (contracts) the section of throttle linkage consisting of the throttle linkage member  16  and the motor  24  that is mounted between and connected to, as described above, the throttle rod  28  and the throttle arm  14 . When the throttle rod  28  is at a position, as for example at the farthest extension to open the throttle butterflies of the fuel metering device  12 , operation of the throttle stop  10  will cause the throttle linkage member  16  to move toward the throttle rod  28  opening the throttle butterflies of the fuel metering device  12 . Operation of the stepper motor  24  of the throttle stop  10  causes the throttle linkage member  16  to move either toward or away from the throttle rod  28  thereby opening or closing the throttle butterflies of the fuel metering device  12 . 
     FIG. 2  shows the fuel metering device  12  and a baseplate style throttle stop  40  according to the present invention. The fuel metering device  12  has butterflies  32  positioned in bores or passages  34  of the fuel metering device. The butterflies  32  are sized and configured to substantially block the passages  34 . The butterflies  32  rotate within the passages  34  from a closed position in which they at least substantially obstruct passage of air through the passages  34  to an open position in which they are aligned with the passages  34  to minimally obstruct air passing through the passages  34 . As shown by  FIG. 2 , the butterflies  32  are at a position between the open and closed positions of the metering device  12 . The butterflies  32  are operated by a throttle control that such as a linkage or cable (not shown). A baseplate  36  is positioned between the fuel metering device  12  and an intake manifold  52 . The baseplate  36  defines passages  44  that are sized and located to align with the passages  34  of the fuel metering device  12 . Butterflies  38  of the throttle stop are sized and configured to substantially conform to the passages  44 . The butterflies  38  are mounted in the passages  44  and rotate from an open position to a closed position as do butterflies  32  of the fuel metering device  12 . 
   A butterfly arm  42  is connected to and extends from each butterfly  38 . A butterfly link  46  is rotatably connected at each of two ends to respective ones of the butterfly arms  42  at a location on the butterfly arm  42  that is separated from the butterfly  38 . The butterfly arms  42  and the butterfly link  46  form a mechanism that causes the butterflies  38  to move together from closed to open positions. A rod  48  is connected to a butterfly arm  42 , as shown, at the location that the butterfly link  46  is rotatably attached to the butterfly arm  42 . The rod  48  extends from the butterfly arm  42  to a threaded end  54 . The threaded end  54  defines threads that extend along the rod  48 . A stepper motor drive  58  engages the threaded end  54  of the rod  48 . The stepper motor  58  draws the rod  48  toward the stepper motor  58  when the stepper motor  58  rotates in a first rotational direction, and extends the rod  48  from the stepper motor  58  when operated to rotate in a second rotational direction that is opposite to the first rotational direction. By drawing in and extending the rod  48 , the stepper motor  58  rotates the butterflies  38  to any position between open and closed in the passages  44  of the baseplate  34 . 
     FIG. 3  shows the fuel metering device  12  and another baseplate style throttle stop  60  according to the present invention. The fuel metering device  12  is as described above by reference to  FIG. 2 . The throttle stop  60  includes a baseplate  36  having passages  44  and butterflies  38  as previously described. The throttle stop  60  includes two gears  62 , one attached to each butterfly  38  to rotate with the butterflies. The gears  62  are sized and positioned to mesh with each other so that both gears  62  and both butterflies  38  rotate. A stepper motor  64  drives a gear  65  that engages one of the gears  62 . The stepper motor  64  rotates in a first rotational direction to rotate the gears  62  and butterflies  38  to a more open position within the passages  44 . The stepper motor  64  rotates in a second rotational direction that is opposite to the first rotational direction to rotate the gears  62  and the butterflies  38  to a more closed position. Causing to the stepper motor  64  to rotate in a selected direction and a selected amount moves the butterflies to a selected position within the passages  44 . 
     FIG. 4  shows a fuel metering device  12  and a baseplate style throttle stop  70  according to the present invention. The throttle stop  70  is distinguished from throttle stop  40  of  FIG. 2  by the addition of a rod  72  extending from the stepper motor  58  and an open switch  74 . The rod  72  moves with the rod  48  that opens and closes the butterflies  38  so that the position of the rod  72  indicates the position of the butterflies  38 . The rod  72  is configured to contact and close the switch  74  when the butterflies  38  are at the full open position. The switch  74  thus provides an indication that the butterflies are at their wide open position. 
   The switch  74  further insures the accuracy of a throttle stop opening. Occasionally, a stepper motor may get stuck and not rotate even though it is receiving stepping pulses from a controller. Also, if the power is interrupted to the controller in the middle of a cycle, the controller can lose track of the position of the throttle stop. Although these problems are rare, by adding the switch  74 , any potential problems are minimized. When the power is first turned on, the controller runs the throttle stop to its wide open position at which point the rod  72  contains the switch  74 . The switch  74  then sends a signal to the controller to indicate that the full stroke or wide open position has been achieved. The controller can then reset its internal counters to the open position. The controller could then reposition the throttle stop at its preset starting position. Each time the throttle stop reaches full open, the counters can be reset. Additionally, a manual calibration switch can be used such that when a racer presses the recalibration switch, the controller causes the throttle stop to move to its fully open position, thereby receiving an open position calibration signal. 
     FIG. 5  shows a fuel metering device  12  and a baseplate style throttle stop  80  according to the present invention. The throttle stop  80  is distinguished from throttle stop  40  of  FIG. 2  by the addition of an encoder  82  to the stepper motor  58 . The encoder  82  monitors movement of the stepper motor  58  and provides an indication of the position of the motor and thereby the rod  48  and the butterflies  38 . That is, the encoder  82  provides feedback information to the stepper motor controller as to the absolute (actual) position of the rod  48  and the butterflies  38 . As such, the encoder provides throttle stop position information. 
     FIG. 6  shows a fuel metering device  12  and a baseplate style throttle stop  90  according to the present invention. The throttle stop  90  is distinguished from throttle stop  40  of  FIG. 2  by the addition of a linear position indicating device  92  mounted to the stepper motor  58 . The linear position indicating device  92  may be a linear potentiometer or linear variable displacement transducer (LVDT) that engages the rod  48 , directly or through intermediate members, to indicate linear movement of the rod  48 . Like the encoder  82 , the linear position indicating device  92  provides feedback information to ensure the accurate positioning of the throttle stop. 
     FIGS. 7A and 7B  show a disc style throttle stop  116 , as described in the above-mentioned U.S. Pat. No. 6,189,505, having a throttle stop actuator  110  mounted to the throttle stop  116 . The actuator  110  includes a stepper motor  112 , a rod  114 , and a linear position indicating device  122 . 
   The throttle stop  116  shown in  FIG. 7A  is mounted beneath a fuel control or metering  12  such as a carburetor. The throttle stop comprises a body having a top half  43  and a bottom half  45 . This body contains the moving parts. The two halves  43  and  45  of the body are bolted together, and the unit is mounted and sealed with gaskets between an intake manifold  52  and the fuel metering device  12 . 
   Two flow control discs  49  (bottom) and  51  (top) are mounted inside the lower body half  45 . The flow control discs are mounted one above the other. The bottom half  45  has a center pin  47 . The bottom flow control disc  49  and the top flow control disc  51  are each mounted for rotation about the center pin  47 . The top flow control disc  51  has holes  53  machined into it that correspond to the bores  34  of the fuel control device  12 . The bottom flow control disc  49  has holes  55  machined into it that also correspond to the bores  34  of the fuel metering device. 
   In the fully opened position of the throttle stop  116 , the holes  53  and  55  are both aligned with one another and with the related bores  34  of the fuel metering device  12 . In this fully opened position, the holes  53  and  55  provide perfectly open bores that match the fuel metering device bores. In this position, there is substantially no restriction to air/fuel flow, so maximum engine horsepower is achieved. The pattern of air/fuel flow, as shown by the path lines  35 , is a straight through uninterrupted and undeflected path. 
   In the fully closed position of the throttle stop  116 , shown in  FIG. 7B , the top flow control disc  51  has been rotated counterclockwise about the pin  47  and the bottom flow control disc  49  has been rotated clockwise about the pin  47 . The fully closed position produces the minimum area of the openings for fuel/air flow. The super imposed, four outlined circles show the fixed, unchangeable locations of the four circular bores  34  of the fuel metering device  12 . 
   The mechanisms for rotating the flow control discs  49  and  51  back and forth between the fully opened position and the fully closed position comprise, as shown in  FIG. 7B , a drive linkage disc  57 , a slave linkage (or driven) disc  59 , an interconnect link  61 , link bars  63  and  65 , a scotch yoke block  67 , and pins  69 ,  71 ,  73 ,  75 ,  77  and  79 . The two link bars  63  and  65  connect the flow control discs  49  and  51  to the drive linkage disc  57  and the slave linkage disc  59 . The interconnect link  61  cross connects the drive linkage disc  57  and the slave linkage disc  59 . The drive linkage disc  57  is rotated by means of the scotch yoke block  67  which is attached to the end of the rod  114  of the throttle stop actuator  110 . 
   The linear position indicating device  122  may be a linear potentiometer or an LVDT. The position indicating device  122  indicates the position of the discs of the throttle stop  116 . 
     FIG. 8  shows a disc-type throttle stop  118 , as described in U.S. Pat. No. 6,189,505, having a throttle stop actuator  130  according to the present invention. The throttle stop  118  does not use linkage discs and connecting links. Instead, the drive linkages comprise rotating gears  138  and  142 , and the linkage discs are replaced with meshing of the gears  138  and  142  that eliminate the interconnect link  61 . The gears  138  and  142  are mounted to drive the flow control discs  49  and  51  (see  FIGS. 7A and 7B ). 
   The throttle stop actuator  130  includes a stepper motor  134  that drives a pinion gear  136 . The stepper motor  134  is positioned so that the pinion gear  136  engages the gear  138 . The stepper motor  134  thereby positions the flow control discs of the throttle stop  116  by drivingly rotating the pinion gear  134  to drive the gears  138  and  142 . 
     FIG. 9  shows a control system  140  for a throttle stop or throttle stop actuator according to the present invention. The control system includes a controller or control module  144  connected to a stepper motor  146  that is a component of a throttle stop according to the present invention. A line  148  provides signals and power to the stepper motor  146  to cause the stepper motor  146  to rotate a characteristic amount or step. The controller  144  provides a number of pulses to the stepper motor  146  to cause the stepper motor to rotate an amount that will cause the throttle stop of which the stepper motor  146  is a component to move to a desired configuration or position. The controller  144  will provide pulses at a rate that will cause the throttle stop of which the stepper motor  146  is a component to actuate at a desired rate. The controller  144  thereby controls both the configuration of the throttle stop of which the stepper motor  146  is a component and the rate at which it changes from one configuration to another. 
   The controller  144  of the control system  140  also controls a transbrake solenoid  152  of a racing vehicle through a line  154  in a conventional manner. A switch  156  is mounted to a line  158  that connects to the controller  144 . The controller  144  is programmed to respond to the activation of the switch  156  by releasing the transbrake. The controller  144  then controls the stepper motor  146  as programmed to provide desired horsepower at programmed times after the switch  156  is activated and/or after the transbrake is released. 
     FIG. 10  shows a control system  160  for a throttle stop or throttle stop actuator according to the present invention. The control system includes a controller  164  connected to a stepper motor  166  that is a component of a throttle stop according to the present invention. A line  168  provides signals and power to the stepper motor  166  to cause the stepper motor  166  to rotate a characteristic amount or step. The controller  164  provides a number of pulses to the stepper motor  166  to cause the stepper motor to rotate an amount that will cause the throttle stop of which the stepper motor  166  is a component to move to a desired configuration or position. The controller  164  will provide pulses at a rate that will cause the throttle stop of which the stepper motor  166  is a component to actuate at a desired rate. The controller  164  thereby controls both the configuration of the throttle stop of which the stepper motor  166  is a component and the rate at which it changes from one configuration to another. 
   The control system  160  also includes a position sensing switch  174 . As described above with reference to the switch  74 , the positioning switch  174  is positioned to be contacted by a member of a throttle actuator that moves to indicate the configuration of the throttle stop. The switch  174  thereby provides an indication to the controller  164  that the throttle stop is at a specified configuration. 
   The control system  160  also includes a line  178  that provides stepper motor position information to the controller  164 . As described above with reference to an encoder  82 , an encoder  182  monitors movement of the stepper motor  166  and provides an indication of the position of the motor  166 , and thereby the configuration of the throttle stop, to the controller  164 . 
   The control system  160  may also include a linear position indicating device  192 . As described above with reference to the linear position indicating device  92 , the linear position indicating device  192  may be a linear potentiometer or LVDT that engages a member of the throttle stop actuator or throttle stop to provide an indication of the position of the throttle stop. 
   The encoder  172  and the linear position indicating device  192  can provide continuous feedback measurements of the position of the throttle stop enabling the controller  164  to assure that a desired configuration is actually achieved. 
   The control system  160  receives a trigger input on a line  208  when a switch  206  is closed. The switch  206  controls a solenoid  212  that controls a device, conventionally a “line lock” or transbrake, that prevents a car from moving from a starting line. As an alternative to the controller  144  that controls the transbrake, the controller  164  only responds to control a throttle stop as programmed when it receives a trigger signal from line  208 . 
   As discussed, positioning of the throttle stop can be accomplished by using an electronic control module. The simplest form of module is an electronic pulser that is started by a trigger input. The pulse rate determines how fast the throttle stop is moved. A more advanced version has an adjustable variable pulse rate so that the rate of change can be varied. 
   An even more advanced controller is a microprocessor control module that is programmable. Movement times, rates of actuator change, and direction (open, close) are programmed individually. A preprogrammed operational curve that includes any throttle stop or throttle stop actuator position at any time can be generated. 
   Another controller is one as described above, but further includes feedback to the controller. This allows for monitoring a variety of data, such as engine rpms, weather conditions, engine exhaust temperatures, intake manifold boost pressures, or engine loads. Adjustments can then be made to the throttle stop to compensate for operating conditions. 
   The system of the present invention can be pre-programmed to operate a throttle stop based only on reaching a desired position, when the desired position is reached, and how fast the throttle stop moves to the desired position (rate). As an example, at a starting line, the throttle stop may initially be at a nearly wide-open position. Then, shortly after a race car leaves the starting line, the throttle stop may be closed at a fairly rapid rate to a nearly closed position. This position could be maintained, and then gradually the throttle stop could be opened up until almost a wide-open position is again reached. The throttle stop could then be held at that position. At some point near the end of the race, the throttle stop could be quickly moved to the wide-open position to provide a quick burst of power. Such a momentary snap opening may even be a manual override of a pre-programmed stop position 
   As such, the system of the present invention may be operated to pre-set the throttle stop position, for example, prior to a race. That is, the throttle stop&#39;s rate of movement, position, and time of position may be set or programmed prior to the race. The system of the present invention does not require information regarding an engine&#39;s is performance. Rather, the position of the throttle stop is predetermined, and the engine performs as it will. 
   The present invention has been described by reference to specific embodiments of the invention. It will be appreciated by those skilled in the art that the invention may be practiced other than as described. For example, and without limitation, constructions and configurations of the throttle stops or throttle stop actuators other than those of the embodiments described herein may be used within the scope of the invention and control of the throttle stop or throttle stop actuators may be provided other than as described. 
   Additionally, for instance, a conventional electric motor can be used in place of a stepper motor. A feedback system would be used to insure accurate positioning of the throttle stop. A variety of feedback systems may be employed such as, as discussed above, an encoder, a linear potentiometer, or an LVDT. 
   Therefore, the invention not be limited to the particular embodiments disclosed. What is sought to be protected is all embodiments falling within the scope of the appended claims.