Patent Publication Number: US-6983736-B2

Title: Governor stabilizer

Description:
FIELD OF THE INVENTION 
   This invention relates to internal combustion engines, and more particularly to a governor assembly for internal combustion engines. 
   BACKGROUND OF THE INVENTION 
   Governors are generally used to regulate the speed of internal combustion engines. Some prior art governors include electronic governors, mechanical governors having centrifugally-responsive flyweights, or air vane governors. A governor maintains an engine at a relatively stable speed. The governor generally receives an input indicative of engine speed, and actuates an engine throttle accordingly to adjust the engine speed to a desired speed. If the engine speed is too low, the governor may adjust the throttle to increase engine speed. If the engine speed is too high, the governor may adjust the throttle to decrease engine speed. 
     FIG. 1  illustrates a prior art governor  310  including flyweights  314  having flanges  318  that move a plunger  322 . The plunger  322  engages a governor lever  326 , which is interconnected to a governor arm  330 . The governor  310  may also include a governor shaft that connects the governor lever  326  to the governor arm  330 . A throttle link  334  is connected to the governor arm  330  and an engine throttle  338 . A governor spring  342  applies a biasing force on the governor arm  330 . The flyweights  314  cause the governor lever  326  to move in response to engine speed, thereby causing the throttle  338  to be adjusted to control engine speed. 
   Conditions associated with governors include speed droop and hunting. The engine speed generally drops when a load is applied to the engine, and this drop in engine speed is called “speed droop.” The amount of speed droop is a characteristic of a particular engine, and is in part determined by spring rate and the tension applied to the governor spring  342 . 
   Hunting, or searching, generally occurs when a governor changes the engine speed. The governor may overshoot the desired engine speed, and the governor then oscillates back and forth about the desired speed until the governor settles on the desired speed. Hunting or searching is the movement back and forth as the governor locates the desired speed. Hunting is also in part determined by spring rate and the tension applied to the governor spring. 
   The governor  310  generally moves the governor arm  330  in response to engine speed. Initially, the engine generally runs at a desired no-load engine speed partly determined by the initial tension of the governor spring  342 . After a load is applied on the engine, the engine speed generally decreases below the desired no-load speed, and the governor  310  adjusts the throttle  338  in an attempt to increase the engine speed to the desired speed. Similarly, after a load is removed, the engine speed increases above the desired no-load speed, and the governor  310  adjusts the throttle  338  in an attempt to decrease the engine speed back down to the desired speed. In the illustrated embodiment, the governor  310  adjusts the throttle  338  by pivoting the governor arm  330 , which actuates the throttle link  334 . The governor spring  342  applies a biasing force on the governor arm  330  and the throttle link  334 . 
   The selection of the spring rate of the governor spring  342  affects the performance of the governor  310 . Droop and hunting are generally functions of the spring rate of the governor spring  342 . The governor spring  342  applies a biasing force on the governor arm  330 . Permanent speed droop may be reduced by lowering the spring rate of the governor spring  342  to reduce the force the governor spring  342  applies on the governor arm  330 . A lower spring rate provides a “looser” feel for the governor  310  and permits the governor  310  to quickly react to speed changes since there is less resistance. However, lowering the spring rate of the governor spring  342  too much generally produces other engine speed concerns, such as hunting or searching. Since the spring rate is lower, the governor spring  342  provides less of a stabilizing force, and the governor  310  may fluctuate about the desired speed. The variation in engine speed caused by hunting causes a surging of the engine. The surging is audible and creates additional noise from the engine. Due to noise restrictions and other factors, additional noise from the engine is generally undesirable. 
   Hunting may be reduced by increasing the spring rate of the governor spring  342  to increase the force the governor spring  342  applies on the governor arm  330 . Increasing the spring rate of the governor spring  342  provides a “tighter” feel for the governor  310  and may help reduce hunting or searching because there is less freedom of movement of the governor arm  330 . However, increasing the spring rate of the governor spring  342  also increases permanent speed droop after a load is applied. Since the spring  342  has a higher spring rate, the governor spring  342  provides more stabilizing force to maintain a steady speed and reduce hunting. However, the additional resistive force of the spring  342  may prevent the governor  310  from actually achieving the desired speed, which results in permanent droop. 
   Due to permanent droop, the desired no-load engine speed often must be increased to compensate for the permanent droop. This is accomplished by increasing the initial tension of the governor spring  342 . For example, if the desired no-load speed for an engine is 3,000 rpm, the permanent droop of the governor may only permit the engine speed to return to 2,800 rpm while a load is applied. Therefore, the engine experiences a permanent speed droop of approximately 200 rpm. The no-load speed may then be increased to 3,200 rpm to permit the engine to achieve the desired engine speed of 3,000 rpm under load, due to the permanent speed droop. Increasing the no-load engine speed also increases the noise generated by the engine. As mentioned above, additional noise from the engine is generally undesirable. 
   In  FIG. 2 , the graph illustrates test data of the engine speed over time in response to various loads placed on an engine having a prior art governor  310  (FIG.  1 ). In the test, the load (measured in Watts “W”) on the engine was from a generator. The engine was subjected to alternating periods of no load, and incrementally increasing loads. The alternating periods of no load and loads were each approximately 40 seconds in duration. In  FIG. 2 , the no-load speed is set at approximately 3800 rpm. Segments  350 ,  358 ,  366 ,  374 ,  382 , and  390  illustrate the engine with no load (represented by “N.L.”) at approximately 3800 rpm. Segments  354 ,  362 ,  370 ,  378 , and  386  show the engine with incrementally increasing loads, in which the engine speed decreases from the previous no load condition. 
   Each decrease in engine speed during the application of a load is a speed droop, and the speed droop increases with increasing loads. In the graph, as the 2050 W load is applied between segments  382  and  386 , the engine speed initially decreases, or undershoots, to about 3200 rpm before increasing back to about 3600 rpm. The approximately 200 rpm difference between 3800 rpm and 3600 rpm represents the permanent speed droop, since it remains the entire time the load is applied. 
   Generally, a governor spring  342 , as shown in  FIG. 1 , having a lower spring rate provides a faster response and more accuracy, but may provide less stability. The governor  310  will quickly get in the general range of the desired engine speed, providing accuracy, but the speed will fluctuate within that range, resulting in less stability. A governor spring  342  having a higher spring rate generally provides more stability, but may have slower response, and less accuracy. The governor  310  will enable the engine to reach a certain engine speed, and will maintain that speed, providing stability. However, that certain engine speed may not be the desired speed, and is normally lower than the desired speed, resulting in less accuracy. 
   SUMMARY OF THE INVENTION 
   The present invention provides an apparatus that helps control the speed of an internal combustion engine having an engine throttle. The apparatus comprises a governor that adjusts the position of the throttle to set the engine speed to a desired speed. The governor includes a governor arm assembly, which may include a governor arm and/or a governor extension that moves in response to engine speed and that engages the governor arm. The governor also comprises a throttle link interconnected to the governor arm assembly and to the throttle. The apparatus also comprises a stabilizer system interconnected to the governor, and preferably to the governor arm assembly. Alternatively, the stabilizer system may be interconnected to the throttle link. The stabilizer system includes a damper and a stabilizer spring interconnected in series to a fixed part of the engine. 
   The stabilizer system creates a temporary droop to stabilize the governor and reduce permanent droop and hunting. Permanent speed droop includes a reduction in engine speed as long as the load is applied, and temporary speed droop includes an initial reduction in engine speed upon application of the load and a substantial return to the original engine speed while the load is still applied. In one embodiment, the stabilizer system temporarily applies a force on the governor arm assembly that initially resists quick movement of the governor arm assembly, and causes a temporary speed droop to inhibit the governor arm assembly from moving too quickly. The initial resistance of the stabilizer spring helps prevent the governor from undershooting or overshooting the desired speed and hunting for the desired speed. After the movement of the governor arm assembly has slowed, the resistive force of the stabilizer system is reduced. The temporary droop is then removed to permit the governor to achieve the desired speed to help prevent permanent droop. 
   The stabilizer system allows the engine to maintain speed and power without setting the desired no-load speed of the governor too high. Since permanent droop is reduced, the desired no-load speed may be lowered, which reduces noise emitted from the engine, and increases fuel efficiency. Additionally, the stabilizer system helps reduce hunting, which also reduces noise emitted from the engine due to surging, and increases fuel efficiency. 
   Independent features and independent advantages of the present invention will become apparent to those skilled in the art upon review of the following detailed description and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram of a prior art governor. 
       FIG. 2  is a graph illustrating engine speed in response to loads for the prior art governor of FIG.  1 . 
       FIG. 3  is a diagram of a governor system including a stabilizer system according to the present invention. 
       FIG. 4  is a perspective view of an engine including the governor system having a stabilizer system. 
       FIG. 5  is a graph illustrating engine speed in response to loads for the governor system including a stabilizer system of FIG.  3 . 
       FIG. 6  is a diagram of another embodiment of a governor system including a stabilizer system. 
       FIG. 7  is a diagram of yet another embodiment of a governor system including a stabilizer system. 
   

   Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
   Although references may be made below to directions, such as left, right, up, down, top, bottom, front, rear, back, etc., in describing the drawings, these references are made relative to the drawings (as normally viewed) for convenience. These directions are not intended to be taken literally or limit the present invention in any form. 
   DETAILED DESCRIPTION 
     FIG. 4  illustrates an internal combustion engine  10  including a governor  14 .  FIG. 3  illustrates a diagram of the governor  14  in more detail. In  FIGS. 3 and 4 , the governor  14  includes centrifugally-responsive flyweights  18  having flanges  19  that move a plunger  24  in response to engine speed. Plunger  24  then moves a governor extension  22 . The centrifugally-responsive flyweights  18  respond to the engine speed, and its flanges  19  cause plunger  24  to move toward the governor extension  22  as the engine speed increases, and away from the governor extension  22  as the engine speed decreases. Flyweights  18  are interconnected with a pinion gear (not shown) that is driven by another gear, as well-known in the art. 
   In the illustrated embodiment, the governor extension  22  is interconnected to a shaft  23 , and the shaft  23  is interconnected to a governor arm  26 . The shaft  23  extends between the governor extension  22  and the governor arm  26 . In the illustrated embodiment, the shaft  23  extends substantially transverse to the governor arm  26 , and the governor extension  22  extends in a substantially radial direction from the shaft  23 . However, the governor extension  22 , governor shaft  23 , and governor arm  26  may be interconnected at a variety of angles. The governor shaft  23  may be used to offset the flyweights  18  and plunger  24  from the governor arm  26 . Alternatively, the governor extension  22  may be connected to the governor arm  26 , and the shaft  23  may not be needed. 
   In  FIG. 3 , the flyweights  18  cause the plunger  24  to move the governor extension  22  in response to engine speed. The governor extension  22  pivots with respect to the shaft  23  in response to movement of the plunger  24 . The governor arm  26  is mounted to pivot with respect to the engine  10 . The pivoting movement of the governor extension  22  causes the shaft  23  to rotate, and rotation of the shaft  23  causes the governor arm  26  to pivot with respect to the engine. The governor arm  26  may pivot in a first direction A when engine speed decreases, and a second opposite direction B when engine speed increases. 
   A throttle link  30  is interconnected to the governor arm  26  and an engine throttle  34 . The throttle  34  regulates the air/fuel mixture that enters the engine  10  to control engine speed, and the throttle link  30  actuates the throttle  34 . The governor  14  also includes a governor spring  38  that applies a biasing force on the governor arm  26  via throttle link  30 . The governor spring  38  includes a first end  42  that is connected to a fixed portion  44  on the engine  10 , and a second end  46  that is interconnected to a moving part of the governor  14 . In the illustrated embodiment, the throttle link  30  includes a loop  50  between the governor arm  26  and the throttle  34 , and the second end  46  of the governor spring  38  is interconnected to the loop  50 . Since the throttle link  30  is interconnected to the governor arm  26 , the governor spring  38  applies a biasing force on the throttle link  30  and the governor arm  26 , and biases the governor arm  26  in the first direction A. 
   Many alternatives of the governor  14  configuration may be used with the present invention. For example, the second end  46  of the governor spring  38  may be connected to governor arm  26 . In the illustrated embodiment, the governor spring  38  is a coil spring, but it could also be a leaf spring, or another type of spring. The throttle link  30  and governor spring  38  could extend from the governor arm  26  in different directions. The governor spring  38  may be connected to a speed adjustment instead of a fixed portion of the engine  10  to vary the speed setting of the governor  14 . 
   A stabilizer system  60  is interconnected to the governor  14  and helps reduce speed droop and other effects of engine speed change, such as hunting or searching. The stabilizer system  60  includes a damper  64  and a stabilizer spring  68 . The damper  64  is connected to a fixed portion  70  on the engine  10 . The stabilizer spring  68  is preferably interconnected between the damper  64  and the governor arm  26 , and includes a first end  72  interconnected to the governor arm  26 , and a second end  76  interconnected to the damper  64 . In another embodiment, the stabilizer spring may be interconnected between the damper  64  and throttle link  30 . In  FIG. 3 , the stabilizer spring  68  is illustrated as a coil spring, and in  FIG. 4 , the stabilizer spring  68  is illustrated as a leaf spring. 
   In  FIGS. 3-4 , the damper  64  includes a cylinder  80  and a rod  84  at least partially disposed within the cylinder  80 . Preferably, the rod  84  is made from a metal or plastic material and may be solid or a hollow tube. The cylinder  80  is preferably made from a plastic or metal material, such as brass, and is tubular. The rod  84  is movable with respect to the cylinder  80 . The configuration of the damper  64  and stabilizer spring  68  permits the stabilizer system  60  to initially resist movement of the governor arm  26 . The stabilizer spring  68  applies a resistive force on the governor arm  26 , and the stored energy of the stabilizer spring  68  then returns the damper  64  to a neutral rest position to reduce the resistive force of the stabilizer spring  68 . Since the stabilizer spring  68  is interconnected to the damper  64  and the governor arm  26 , the stabilizer system  60  resists sudden movement of the governor arm  26 , but does not necessarily prevent movement of the governor arm  26 . 
   In  FIG. 3 , the stabilizer spring  68  is interconnected to the rod  84 , and the cylinder  80  is connected to the portion  70  on the engine  10 . The damper  64  may also be reversed, with the stabilizer spring  68  interconnected to the cylinder  80 , and the rod  84  connected to the engine  10 . Additionally, the damper  64  and stabilizer spring  68  could be reversed, with the damper  64  interconnected to the governor arm  26 , and the stabilizer spring  68  interconnected between the damper  64  and a fixed portion of the engine  10 . The damper  64  and stabilizer spring  68  are preferably connected in series between the governor arm  26  and fixed portion of the engine  10 . 
   In  FIGS. 3-4 , the damper  64  may provide pneumatic damping, friction damping, and/or viscous damping. The governor arm  26  pivots about a fixed point, so the first end  72  of the stabilizer spring  68  interconnected to the governor arm  26  travels in an arc-shaped path. Therefore, the stabilizer spring  68  and rod  84  may also travel in an arc-shaped path. The cylinder  80  may be connected to a fixed portion of the engine  10 , and the rod  84  is free to move within the cylinder  80 . As the rod  84  moves in an arc-shaped path, the rod  84  may contact the relatively straight cylinder  80  to create friction damping for the stabilizer system  60 . 
   In the illustrated embodiment, a flexible mount  86  is disposed between the cylinder  80  and the fixed portion  70  of the engine  10 . The flexible mount  86  may be made from rubber, or some other similar flexible, durable material. The flexible mount  86  permits the cylinder  80  to move slightly in relation to the engine  10  to accommodate the arc-shaped path of the rod  84 . The flexible mount  86  and movable cylinder  80  helps align the rod  84  and cylinder  80 , and helps reduce friction between the rod  84  and cylinder  80 . 
   The cylinder  80  includes an open end  88  and a closed end  92 . The closed end  92  may be interconnected to the engine  10 , and the rod  84  may extend into the cylinder  80  through the open end  88 . In the illustrated embodiment, the closed end  92  is interconnected to the engine  10  with the flexible mount  86 . The outer diameter of the rod  84  is less than the inner diameter of the cylinder  80 , and the rod  84  may move with respect to the cylinder  80 . The fit between the rod  84  and the cylinder  80  is relatively close and may restrict air movement between the rod  84  and cylinder  80 , but the fit is not airtight to prevent air from travelling between the rod  84  and cylinder  80 . 
   As the rod  84  moves into the cylinder  80 , the air within the cylinder  80  is under compression and resists movement of the rod  84 . The rod  84  forces air out of the cylinder  80 . As the rod  84  moves out of the cylinder  80 , the air within the cylinder  80  creates a vacuum that resists movement of the rod  84 . The movement of the rod  84  out of the cylinder  80  draws air into the cylinder  80 . Once the air moves into or out of the cylinder  80 , the pressure within the cylinder  80  is equalized and the resistive force of the stabilizer system  60  is reduced. Therefore, the damper  64  also provides pneumatic damping for the stabilizer system  60 . 
   The damper  64  may also provide viscous damping. A light grease may be applied between the inner surface of the cylinder  80  and the rod  84 . The grease provides a viscous damping between the cylinder  80  and the rod  84  and assists the stabilizer system  60  in providing a temporary resistance on the governor arm  26 . 
     FIG. 3  illustrates the governor  14  including the stabilizer system  60 . The stabilizer system  60  creates a temporary droop to stabilize the governor  14  and reduce hunting or searching. The temporary droop is then removed to permit the governor  14  to achieve the desired speed to help prevent permanent droop. The stabilizer spring  68  temporarily applies a force on the governor arm  26  that initially resists movement of the governor arm  26 . The stabilizer system  60  causes a temporary speed droop to inhibit the governor arm  26  from moving too quickly. The initial resistance of the stabilizer spring  68  helps prevent the governor  14  from undershooting or overshooting the desired speed and hunting for the desired speed. Reducing hunting helps reduce surging and noise generated by the engine, and helps increase fuel efficiency of the engine. 
   Once the damper  64  returns to a neutral or equilibrium position, the stored energy in the spring  68  is released and the resistive force of the stabilizer spring  68  on the governor arm  26  is reduced. The stabilizer system  60  initially applies a resistive force that resists sudden movement of the governor arm  26 , but the resistive force decreases as the movement of the governor arm  26  slows. As the resistive force is reduced, the temporary droop is also reduced, and the governor  14  may reach the desired engine speed. The stabilizer system  60  applies a temporary droop to help prevent unstable action or hunting. After the temporary droop is eliminated, the governor  14  may achieve the desired speed. Since the stabilizer system  60  slows movement of the governor  14 , the governor  14  generally achieves the desired speed without excessive hunting or instability. 
   The damper  64  resists sudden movement, and causes the stabilizer spring  68  to apply a resistive force on the governor arm  26 . The resistance provided by the stabilizer system  60  is generally proportional to the rate of movement of the governor arm  26 . The stabilizer system  60  and stabilizer spring applies a greater resistive force during quick movement of the governor arm  26  than during slow movement of the governor arm  26 . The stabilizer system  60  permits the governor  14  to include a governor spring  38  having a lower spring rate, which can accommodate slow movement of the governor arm  26 . Quick movement of the governor arm  26  is generally the cause of hunting for a governor spring  38  having a low spring rate. The stabilizer system  60  generally provides a resistive force on the governor arm  26  when it moves quickly, and may have a minimal effect when it moves slowly. 
   The stabilizer system  60  performs a function similar to altering the spring rate of the governor spring  26  when needed to help reduce hunting and permanent droop, and achieves the benefits of selectively having a governor spring  38  with a high spring rate and a low spring rate. The stabilizer system  60  allows the governor  14  to include a governor spring  38  having a lower spring rate, while helping to prevent hunting. The lower spring rate may result in the governor  14  having no droop, or possibly even a speed gain, or negative droop. In a speed gain, the governor  14  may actually exceed the desired no-load engine speed after a load is applied on the engine, resulting in increased engine power output. 
   In  FIG. 5 , the graph illustrates test data of the engine speed over time in response to various loads placed on an engine having a governor  14  including a stabilizer system  60  (FIG.  4 ). The load on the engine was from a generator and is measured in Watts (W). The engine and generator for  FIG. 5  were substantially the same as that used for Prior Art  FIG. 2 , a 2000 W, 60 Hertz (Hz) generator and a 5 HP engine, with the exception of the governor  14  including the stabilizer system  60  ( FIG. 4 ) used in FIG.  5 . The engine was again subjected to alternating periods of no load (represented by “N.L.”), and incrementally increasing loads. In  FIG. 5 , the no-load speed is set at approximately 3600 rpm. Due to the lack of speed droop, the no-load engine speed may be set lower for the engine with the governor  14  and stabilizer system  60  (FIG.  4 ). Segments  410 ,  418 ,  426 ,  434 ,  442 , and  450  illustrate the engine with no load at approximately 3600 rpm. Segments  414 ,  422 ,  430 ,  438 , and  446  show the engine with incrementally increasing loads. 
   In  FIG. 5 , the engine speed returns to about the set no-load engine speed of 3600 rpm after each load is applied. In some instances, the engine speed actually increased above the no-load speed after the application of a load. At segment  438 , the engine speed increases slightly above 3600 rpm after the 1640 W load is applied. This increase in speed shown at segment  438  after the application of the load is an example of the negative droop, or speed gain that may result from the governor  14  including the stabilizer system  60  shown in FIG.  4 . 
   The stabilizer system  60  allows the engine  10  to maintain speed and power without setting the desired no-load speed of the governor  14  too high. Since permanent droop is reduced, the desired no-load speed may be lowered, which reduces noise emitted from the engine, and increases fuel efficiency. Additionally, the stabilizer system  60  helps reduce hunting, which also reduces noise emitted from the engine due to surging, and increases fuel efficiency. 
     FIG. 6  illustrates another embodiment of a stabilizer system  160  interconnected to the governor  14 . The governor  14  shown in  FIG. 6  is substantially the same as the governor  14  described above and shown in FIG.  3 . The stabilizer system  160  illustrated in  FIG. 6  functions similarly to the stabilizer system  60  described above and shown in FIG.  3 . The stabilizer system  160  includes a damper  164  and a stabilizer spring  168 . The damper  164  is mounted to a fixed portion  170  on the engine  10 . The stabilizer spring  168  is interconnected between the damper  164  and the governor arm  26 , and includes a first end  172  interconnected to the governor arm  26 , and a second end  176  interconnected to the damper  164 . In the illustrated embodiment, the stabilizer spring  168  is connected to the governor arm  26  with a clamp  178 . In  FIG. 6 , the stabilizer spring  168  is a leaf spring made from a flexible material, such as metal or plastic. 
   The damper  164  includes a cylinder  180  and a rod  184  at least partially disposed within the cylinder  180 . Similar to the embodiment described above, a flexible mount  186  may be disposed between the cylinder  180  and the fixed portion  170 . The cylinder  180  includes an open end  188  and a closed end  192 . The rod  184  extends into the open end  188  of the cylinder  180 , and is movable with respect to the cylinder  180 . The outer diameter of the rod  184  is preferably less than the inner diameter of the cylinder  180 . In the illustrated embodiment, the rod  184  is interconnected to the stabilizer spring  168 , and the cylinder  180  is connected to the engine  10 . The end of the rod  184  may be threaded, and a fastener  104 , such as a nut, may be used to connect the rod  184  to the stabilizer spring  168 . The cylinder  180  may include a base  108  near the closed end  192  to help seal that end of the cylinder  180  and connect the cylinder  180  to the engine  10 . The damper  164  could be reversed, with the stabilizer spring  168  interconnected to the cylinder  180 , and the rod  184  connected to the engine  10 . 
   The damper  164  also includes a sleeve  112  that at least partially surrounds the rod  184  and the cylinder  180 . In  FIG. 6 , the sleeve  112  includes a first end  116  interconnected to the rod  184  near the stabilizer spring  168 , and a second end  120  opposite the first end  116 . The damper  164  may include a cap  124  disposed between the sleeve  112  and the stabilizer spring  168 , near the first end  116  of the sleeve  112 . The cap  124  may be integral with the sleeve  112 , and may help seal the first end  116  of the sleeve  112 . The damper  164  may also include a magnet  128  disposed near the first end  116  of the sleeve  112 , between the sleeve  112  and the stabilizer spring  168 . If the stabilizer spring  168  is made of metal, the magnet  128  may connect the damper  164  to the stabilizer spring  168 . The fastener  104  may not be needed if the damper  164  includes the magnet  128 . 
   The sleeve  112  helps prevent contaminants, such as dust, debris, or other particles, from entering the cylinder  180  and becoming lodged within the cylinder  180  or between the cylinder  180  and the rod  184 . The rod  184  moves with respect to the cylinder  180 , and there is a relatively close fit between the rod  184  and cylinder  180 . Due to the movement of the rod  184 , contaminants caught between the rod  184  and cylinder  180  could cause additional wear on the parts. The sleeve  112  may include a wiper  132  near the second end  120  of the sleeve  112  to help prevent contaminants from entering the sleeve  112  and the cylinder  180 . Since the sleeve  112  also moves with respect to the cylinder  180 , the wiper  132  may be made from a relatively soft material, such as felt, that does not damage the cylinder  180 , but is still permeable to permit air to pass through the wiper  132 . 
   In  FIG. 6 , the sleeve  112  is spaced apart from the cylinder  180 . Alternatively, the sleeve  112  may be relatively close to the cylinder  180 , similar to the fit between the cylinder  180  and the rod  184 . In this embodiment, the tighter fit between the rod  184 , cylinder  180 , and sleeve  112  may provide a greater damping force for the damper  164 . The damper  164  may also include a flexible seal interconnected to the cylinder  180  and the sleeve  112  to help prevent contaminants from entering the sleeve  112  and wearing on the sleeve  112  and cylinder, due to the tighter fit of the sleeve  112  and cylinder  180 . 
     FIG. 7  illustrates another embodiment of a stabilizer system  260  interconnected to the governor  14 . In  FIG. 7 , the stabilizer system  260  includes a spring-mass damper  264  interconnected to the governor arm  26 . The governor  14  is similar to the governor  14  described in the embodiments above. The damper  264  includes a mass  210 . A spring  214  is interconnected between the mass  210  and the governor arm  26 . In the illustrated embodiment, the mass  210  is pivotally connected to a bracket  218 , and the bracket  218  is connected to a fixed portion of the engine  10 . The mass  210  may pivot with respect to the engine  10 . 
   As mentioned above, the governor arm  26  moves in response to changes in engine speed. As the governor arm  26  moves, the spring  214  initially applies a resistive force on the governor arm  26 . Since the mass  210  is initially at rest, the mass  210  tends to stay at rest, and a certain amount of force is required to move the mass  210 . When the governor arm  26  moves suddenly, the mass  210  remains at rest, and the spring  214  applies a resistive force on the governor arm  26 . The stored energy in the spring  214  eventually causes the mass  210  to move, and the resistive force applied by the spring  214  is reduced as the mass  210  moves to a new rest position. 
   The foregoing detailed description describes only a few of the many forms that the present invention can take, and should therefore be taken as illustrative rather than limiting. It is only the claims, including all equivalents that are intended to define the scope of the invention.