Patent Publication Number: US-6336648-B1

Title: Electronically controlled anti-dive suspension apparatus for two-wheeled vehicles

Description:
This application is a continuation-in-part of application Ser. No. 08/991,585, filed Dec. 15, 1997 now U.S. Pat. No. 6,050,583 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to suspension systems for two-wheeled vehicles, such as mountain bikes and motorcycles, and, more particularly, is concerned with an electronically controlled anti-dive suspension apparatus for actively adjusting the front suspension of the two-wheeled vehicle to counteract the initiation of a dive condition due to “hard” braking by the cyclist. 
     2. Description of the Prior Art 
     In recent years suspension systems on bicycles, particularly on mountain bikes, have become more common. Some examples of bicycle suspension systems are the ones disclosed in U.S. Pat. No. 4,679,811 to Shuler, U.S. Pat. No. 4,881,750 to Hartmann, U.S. Pat. No. 5,044,648 to Knapp, U.S. Pat. Nos. 5,308,099 and 5,509,674 to Browning, U.S. Pat. Nos. 5,445,401 and 5,509,677 to Bradbury, and U.S. Pat. Nos. 5,456,480 and 5,580,075 to Turner et al. 
     A common drawback of most suspension systems is that they are passive mechanical systems which do not sense change in riding conditions nor automatically adjust in response thereto. This results in suspension systems that may be too stiff for extremely rocky, steep descents and too soft for riding on surfaced roads and bike paths. Some suspension systems allow the rider to adjust the pretension on the suspension components. However, this process normally requires stopping the bicycle to manually make the necessary adjustments. The rider must estimate the stiffness or softness that might be required for the anticipated riding conditions. Also, the adjustments in some of these systems require the use of tools. 
     The above-cited Turner et al. U.S. Pat. No. 5,456,480 contains a caution to designers that electronic control of bicycle suspensions is impractical. This statement seems intended to discourage any attempts to improve bicycle suspensions through the development of an electronically-based solution to controlling the suspensions in order to adjust to different riding conditions. Nevertheless, it is the perception of the inventor herein that a different approach, possibly one that is electronically-based, is needed in the design of suspension systems for two-wheeled vehicles, such as on mountain bikes and motorcycles, to improve their handling and performance. 
     This is especially the case during “hard” braking of the mountain bike or motorcycle by the cyclist when it is common for the front suspension to “dive” causing the vehicle to rock forward. Then, once braking has stopped, the suspension causes the bike to “rock” back. Such rocking motion can be particularly hazardous for a cyclist on a mountain bike during a steep descent which in combination with hard braking can result in the cyclist flying over the handlebars and for a cyclist on a motorcycle while hard braking prior to entering a sharp corner followed by an acceleration when exiting the corner. 
     SUMMARY OF THE INVENTION 
     The present invention provides an electronically controlled anti-dive suspension apparatus for a two-wheeled vehicle designed to satisfy the aforementioned need. The anti-dive suspension apparatus of the present invention employs an electronics module, sensor means, actuator means and power source in conjunction with a front suspension on a two-wheeled vehicle for actively adjusting the front suspension of the two-wheeled vehicle to counteract the initiation of a dive condition due to braking by the cyclist. The sensor means actively senses the deceleration of the vehicle due to the application of the brakes and produces signals representative thereof as inputs to the electronics module which processes the inputs and produces an output causing activation of the actuator means to adjust the front suspension system to “stiffen” it so as to prevent its contraction and the resulting dive of the front end of the vehicle downward toward the front wheel and thus the ground. 
     Accordingly, the present invention is directed to a electronically controlled anti-dive suspension apparatus for use on a two-wheeled vehicle. The apparatus comprises: (a) a front suspension system mounted to and between first and second parts of a two-wheeled vehicle movable relative to and toward one another in response to a braking action being applied to the vehicle, the front suspension system including first means connected between the first and second relative movable parts of the vehicle and being contractible in response to the first and second vehicle parts moving toward one another due to the braking action and second means connected to the first means for controlling the amount of contraction of the first means; (b) means mounted to either one of the first and second relative movable parts of the vehicle for sensing deceleration of the vehicle due to the braking action and producing an input representative thereof; (c) an electronics module mounted to the vehicle and connected to the sensing means for receiving and processing the input from the sensing means to produce an output corresponding to a desired predetermined response to the deceleration of the vehicle sensed by the sensing means; (d) at least one actuator mounted to the vehicle and coupled to the suspension system for receiving the output from the electronics module and in response thereto causing the second means of the suspension system to reduce the amount of contraction of the first means and thereby prevent the resulting dive of the front end of the cycle downward toward the ground; and (e) means for electrically powering the sensing means, the electronics module and the at least one actuator. 
     More particularly, the first means of the suspension system includes a cylinder having telescoping members defining an interior cavity and respectively connected to the first and second parts of the vehicle movable relative to one another and movable toward and away from one another between predetermined limits, and an extendable and contractible spring disposed within the interior cavity being biased to force the telescoping members away from one another. The second means of the suspension system includes a fluid contained in the interior cavity and a partition fixed across said interior cavity inside one of the telescoping members to divide the interior cavity into separate chambers in the telescoping members. The partition defines at least one orifice having a predetermined size for controlling a rate of flow of the fluid between the chambers of the telescoping members so as to control the contraction of the spring and thereby control the movement of the telescoping members toward one another. The actuator is coupled to the cylinder of the first means of the suspension system and movable relative thereto to change the size of the orifice of the partition of the second means of the suspension system. The sensing means preferably is an accelerometer. The electrical powering means preferably is at least one battery. 
     These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following detailed description, reference will be made to the attached drawings in which: 
     FIG. 1 is a diagrammatic representation of an electronically controlled suspension apparatus which can function as an anti-dive suspension apparatus in accordance with the present invention when connected to a front suspension of a two-wheeled vehicle. 
     FIG. 2 is a block diagram of the apparatus. 
     FIG. 3 is an exploded view of the apparatus. 
     FIG. 4 is an assembled view of the apparatus. 
     FIG. 5 is an elevational view of the apparatus of FIG. 4 without the electronics module. 
     FIG. 6 is another elevational view of the apparatus rotated 90° from the position of FIG.  5 . 
     FIG. 7 is a top plan view of the apparatus as seen along line  7 — 7  in FIG.  6 . 
     FIG. 8 is a diagrammatic view showing a two-wheeled vehicle having a front suspension system to which the apparatus of the present invention can be applied. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and particularly to FIGS. 1 to  4 , there is illustrated an electronically controlled suspension apparatus, generally designated  10 , of the invention of the cross-referenced original application of the inventor herein. Basically, the apparatus  10  includes a suspension system  12 , sensing means  14 , an electronics module  16 , at least one actuator  18  and an electrical powering means  20  for supplying electrical power to the sensing means  14 , electronics module  16  and actuator means  18 . The suspension system  12  is generally mounted to and extends between parts of a two-wheeled vehicle, such as a bicycle. For example, as shown diagrammatically in FIG. 1 the bicycle frame F and bicycle wheel support W pivotally mounted to the bicycle frame F are movable relative to one another in response to a shock applied to the bicycle. The suspension system  12  could be attached either one or both of the rear wheel support or front wheel support. In the case of being attached to the front wheel for performance as the anti-dive suspension apparatus of the present invention, the support with the suspension system incorporated therein usually is in the form of dual suspension forks. In the case of being attached to the rear wheel, the suspension is usually implemented through a pivotal connection to the bicycle frame and to the rear wheel support arm. 
     The suspension system  12  includes first means  22  connected between the aforementioned parts F, W of the bicycle and capable of absorbing shock applied to the bicycle and second means  24  connected to the first means  22  for controlling the degree of shock absorbing capability of the first means  22 . The sensing means  14  is mounted to either one of the aforementioned relative movable parts of the bicycle to which the suspension system  12  is connected in responding to a shock applied to the bicycle, and is provided for sensing one, two or all of a plurality of conditions including forward velocity, tilt and vertical acceleration of the bicycle and producing an input I representative thereof to the electronics module  16 . The electronics module  16  is mounted to the bicycle and connected to the sensing means  14  for receiving the input L from the sensing means  14  and processing the input L to produce an output M corresponding to a desired predetermined response to the one, two or all of the conditions sensed by the sensing means  14 . The actuator means  18  is mounted to the bicycle and coupled to the suspension system  12  for receiving the output M from the electronics module  16  and in response thereto causing the second means  24  of the suspension system  12  to affect the first means  22  of the suspension system  12  so as to actively adjust the suspension system  12  to accommodate the immediate surface conditions experienced by a user of the bicycle so as to improve control over the riding of the bicycle by the user under such immediate surface conditions. 
     Referring now to FIGS.  1  and  3 - 7 , the first means  22  of the suspension system  12  includes a cylinder  26  having outer and inner tubular telescoping members  28 ,  30  defining an interior cavity  32  in the cylinder  26  and respectively connected to the parts F, W of the bicycle which are slidably movable in telescoping relation with respect to one another. The telescoping members  28 ,  30  of the cylinder  26  are movable toward and away from one another between predetermined limits. The outer telescoping member  28  of the cylinder  26  has a tubular body portion  28 A open at one end  28 B and closed at the opposite end by a base  28 C with a threaded bore  28 D defined therethrough. The inner telescoping member  30  of the cylinder  26  is made of an upper header tube  34  and a lower extension tube  36 . A head end  36 A of the lower extension tube  36  is received in and fastened to a bottom end  34 A of the upper header tube  34  such that the upper header tube  34  and lower extension tube  36  will function together as the unitary inner telescoping member  30  of the cylinder  26 . Adjacent to the head end  36 A of the lower extension tube  36 , the upper header tube  34  has a plate-like partition  38  fixed across the interior cavity  32  with an aperture  40  defined centrally therethrough. 
     The predetermined limit of retraction of the outer and inner telescoping members  28 ,  30  toward one another is established by the head end  36 A of the lower extension tube  34  of the inner telescoping member  30  engaging the open end  28 B of the outer telescoping member  28 . The predetermined limit of extension of the outer and inner telescoping members  28 ,  30  away from one another is established by an elongated tension bolt  42  of the first means  22  that extends through the central aperture  40  of the partition  38  and is threaded at its lower end  42 A into the threaded bore  28 D of the base  28 C of the outer member  28 . The tension bolt  42  has an enlarged head  42 B thereon that engages the upper side of the partition  38  when the outer and inner telescoping members  28 ,  30  are fully extended away from one another as seen in FIGS. 5 and 6. The open end  30 A of the inner telescoping member  30  opposite from the upper header tube  34  and the open end  28 B of the body portion  28 A of the outer tube  28  both have respective  0 -rings  44  mounted thereto for providing hermetic seals between the outer and inner telescoping members  28 ,  30  while accommodating their relative sliding movement. The first means  22  also includes an extendable and contractible coil spring  46  disposed within the interior cavity  32  of the cylinder  26  being biased to force the outer and inner telescoping members  28 ,  30  to move or extend away from one another. 
     The second means  24  of the suspension system  12  includes a fluid  48  contained in the interior cavity  32  and the aforementioned partition  38  fixed across the interior cavity  32  inside the upper header tube  34  of the inner telescoping members  30  so as to divide the interior cavity  32  into a pair of separate chambers  32 A,  32 B in the outer and inner telescoping members  28 ,  30 . The partition  38  defines at least one and, preferably, a pair of orifices  50  therethrough on opposite sides of the central aperture  40 . The orifices  50  are provided with respective predetermined sizes for controlling the rate of flow of the fluid  48  between the chambers  32 A,  32 B of the cylinder  26  so as to control contraction of the spring  46  and thereby control movement of the outer and inner telescoping members  28 ,  30  toward one another in absorbing the shock applied to the bicycle. This arrangement is commonly referred to as a variable oil damper. In an exemplary embodiment illustrated in FIGS. 5-7, a pair of orifices  50  are provided through the partition  38 , with the size of one of the orifices  50  preferably being greater than the size of the other of the orifices  50 . For instance, the size of one orifice  50  may be about half the size of the other orifice  50 . However, it should be understood that this is by way of example only, since only one orifice  50  can be used to practice the invention. 
     The sensing means  14  of the apparatus  10  preferably, but not necessarily, is a biaxial accelerometer, such as a commercially available Humphrey LA02 device or an Analog Devices ADXL05 device or an Analog Devices ADXL202 device. The biaxial accelerometer  14  operates along two axes disposed in substantially orthogonal or perpendicular relation to one another. One axis of the accelerometer  14  is oriented parallel to the forward direction of travel of the bicycle along a horizontal axis H and the other axis is oriented parallel to the gravitational vector along a vertical axis V. The biaxial accelerometer  14  along its horizontal axis H measures forward velocity and tilt of the bicycle and along its vertical axis V measures vertical acceleration of the bicycle. The measurements along these two axes are combined to produce the input L representative thereof. The input L includes two signals, one a DC signal and the other an AC signal. The tilt (T) of the bicycle is determined by the DC signal variation in the H direction compared to the gravitational vector. From this electrical calculation the amount of tilt, either inclination or declination, can be determined. The forward velocity (FV) is determined by an integration of the acceleration in the H direction. The vertical acceleration (VA) is determined by direct measurement of the AC signal amplitude in the V direction. The vertical acceleration of the bicycle is the principal condition which indicates the degree of roughness or smoothness of a riding surface and is parallel to the normal force of the riding surface. 
     While a single biaxial accelerometer is the preferred type of sensor means  14 , different combinations of sensors could be used to accomplish the same sensor input to the electronics module  16 . In the case of using only the forward velocity and tilt as the input this could be accomplished using other types of sensing technology. For example, the speed could be sensed by a Hall effect type sensor attached to one of the wheels. The tilt could be sensed using a fluid level sensor. 
     The electronics module  16  can be a conventional microcontroller, such as a commercially available Motorola MC68HC11 or an Intel 80C51BH, but can be of any other suitable make. The input L from the sensing means  14 , after undergoing amplification and conditioning at block  52  shown in FIG.  2  and then conversion from analog to digital form at block  54  also shown in FIG. 2, is provided to the electronics module  16  which then processes the input L and produces output M. The output M adjusts the actuator means  18 . It is believed that one of ordinary skill in the art would be able to program a conventional microcontroller or microprocessor to produce the desired output M from the input L without having to exercise an undue amount of experimentation to accomplish the task. One practical example of a scheme for operation of the electronics module  16  in receiving and processing of the input L and producing output M is provided hereinafter. Different combinations of input L and output M of this example are shown in Table 1. 
     As set forth above, the signals making up input L represent the tilt (T), forward velocity (FV) and vertical acceleration (VA) of the bicycle. As mentioned above, the DC signal represents the tilt (T) and has separate values designated as “o” for when the bicycle is traveling on level ground with an angle of 5 degrees or less, “+” for going up a hill of more than 5 degrees and “−” for going down a hill of more than 5 degrees. Combinations of these values for input M are shown in Table 1. As mentioned before, the forward velocity is determined by integrating the acceleration in H direction and the vertical acceleration is the amplitude of the AC signal in the V direction. The forward velocity (FV) has separate values designated as “−” for when the bicycle has a forward velocity in a low range of less than 8 miles per hour, “o” for a mid range of 8 to 15 miles per hour, and “+” for a high range of more than 15 miles per hour. The vertical acceleration (VA) has separate values designated as “−” for when the bicycle is experiencing a vertical acceleration in a low range of less than 0.1 g&#39;s, “o” for a mid range of 0.1 to 1.0 g&#39;s and “+” for a high range of more than 1.0 g&#39;s. The combinations of these values are also presented in Table 1. As far as the above ranges of values for tilt, forward velocity and vertical acceleration are concerned, these are given herein as examples only; other ranges could equally be selected for use. 
     The output M, as mentioned, corresponds to a desired predetermined response to the input L, which represents one, two or all of forward velocity, tilt and vertical acceleration of the bicycle. The output M will signal the actuator means  18  to either open or to close the orifice(s)  50  depending on the combination of values of the input L presented. The closing of the orifice(s)  50  stiffens the suspension system  12 , whereas the opening of the orifice(s)  50  softens the suspension system  12 . Also the desired adjustment to the suspension system  12  might be different whether it is associated with the front or rear wheel of the bicycle. 
     Where a pair of actuators  18  and orifices  50  are employed, the output M has four possible combinations of values for an actuator A 1  (working on the smaller size orifice) and an actuator A 2  (working on the larger size orifice) as follows: “0 and 0”, “1 and 0”, “0 and 1” and “1 and 1” which respectively correspond to adjustment to a hard (stiff), half-hard, half-soft and soft suspension for the riding surface being encountered by the rider. The number bogs means orifice is closed; the number “1” means the orifice is open. The resulting combinations of output M values corresponding to the various combinations of input L values are shown in Table 1. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Input (L) 
                 Output (M) 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 No. 
                 T 
                 FV 
                 VA 
                 A1 
                 A2 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 o 
                 + 
                 + 
                 1 
                 1 
               
               
                   
                 2 
                 o 
                 + 
                 − 
                 0 
                 0 
               
               
                   
                 3 
                 o 
                 + 
                 o 
                 1 
                 0 
               
               
                   
                 4 
                 o 
                 o 
                 + 
                 0 
                 1 
               
               
                   
                 5 
                 o 
                 o 
                 − 
                 1 
                 1 
               
               
                   
                 6 
                 o 
                 o 
                 o 
                 1 
                 0 
               
               
                   
                 7 
                 o 
                 − 
                 + 
                 0 
                 1 
               
               
                   
                 8 
                 o 
                 − 
                 − 
                 0 
                 0 
               
               
                   
                 9 
                 o 
                 − 
                 o 
                 1 
                 0 
               
               
                   
                 10 
                 + 
                 + 
                 + 
                 0 
                 1 
               
               
                   
                 11 
                 + 
                 + 
                 + 
                 0 
                 0 
               
               
                   
                 12 
                 + 
                 + 
                 o 
                 1 
                 0 
               
               
                   
                 13 
                 + 
                 o 
                 + 
                 0 
                 1 
               
               
                   
                 14 
                 + 
                 o 
                 − 
                 0 
                 0 
               
               
                   
                 15 
                 + 
                 o 
                 o 
                 1 
                 0 
               
               
                   
                 16 
                 + 
                 − 
                 + 
                 1 
                 1 
               
               
                   
                 17 
                 + 
                 − 
                 − 
                 0 
                 0 
               
               
                   
                 18 
                 + 
                 − 
                 o 
                 0 
                 0 
               
               
                   
                 19 
                 − 
                 + 
                 + 
                 0 
                 0 
               
               
                   
                 20 
                 − 
                 + 
                 − 
                 1 
                 1 
               
               
                   
                 21 
                 − 
                 + 
                 o 
                 1 
                 0 
               
               
                   
                 22 
                 − 
                 o 
                 + 
                 1 
                 1 
               
               
                   
                 23 
                 − 
                 o 
                 − 
                 0 
                 0 
               
               
                   
                 24 
                 − 
                 o 
                 o 
                 1 
                 0 
               
               
                   
                 25 
                 − 
                 − 
                 + 
                 1 
                 1 
               
               
                   
                 26 
                 − 
                 − 
                 − 
                 0 
                 0 
               
               
                   
                 27 
                 − 
                 − 
                 o 
                 1 
                 0 
               
               
                   
                   
               
            
           
         
       
     
     A few typical riding environments and corresponding adjustments are as follows: 
     (1) Fast cycling on a hard, level surface; referring to No. 2 above, the input (L) would be: tilt (T) is level (o), forward velocity (FV) is high (+) and vertical acceleration (VA) is low (−); the output (M) would be: close both orifices so A 1  and A 2  would both be 0. The result is a stiff suspension system  12  for better handling and more efficient energy transfer to the bicycle wheels. 
     (2) Slow, steep descent on a rocky single track trail; referring to No. 25 above, the input (L) would be: tilt (T) is downhill or negative (−), forward velocity (FV) is low (−) and vertical acceleration (VA) is high (+); the output (M) would be: open both orifices so A 1  and A 2  would both be 1. The result is soft suspension system  12  for better handling of bicycle. These represent only two possible riding situations. As mentioned above, the output would likely be different based on whether the output is being sent to the front or rear suspension. For example, there may be certain riding situations where a stiff rear suspension should be combined with a soft front suspension. This situation would occur during an ascent up a rocky single track trail. 
     In the illustrated example, the actuator means  18  is a pair of actuators  18 , such as reciprocable solenoid types, which are operable in conjunction with the pair of orifices  50  of the partition  33  of the second means  24  of the suspension system  12 . Each actuator  18  is coupled to the cylinder  26  of the first means  22  of the suspension system  12  and movable relative thereto to change the size of its respective one of the orifices  50  of the partition  38  of the second means  24  of the suspension system  12  to correspondingly change the rate of fluid flow through the orifice  50 . Each actuator  18  has a size congruent with the size of the orifice  50  which it moves in relation to. Although the illustrated example shows a pair of actuators  18  operable in conjunction with the pair of orifices  50 , it should be clearly understood that this is only one option. Only one actuator  18  operable in conjunction with only one orifice is another option. Also, each actuator  18  can take other forms, such as a motor and rotary valve instead of a reciprocatory solenoid, or a piezoelectric valve, such as available from ACX of Cambridge, Mass. Also each actuator can be a type which undergoes a proportionate type of movement. 
     The electrical powering means  20  is at least one battery of any suitable type, such as two AA batteries. As represented respectively by blocks  56 ,  58 ,  60  in FIG. 2, the apparatus  10  may also have a means for providing user inputs for overriding the automatic adjustment operation, a display for the electronics module  16  and/or an actuator feedback sensor. With respect to the user override input  56 , the user override would be used to set the suspension system  12  to a known stiffness setting; for example, for a long ride over pavement the user might choose to lock the suspension system  12  in the stiff position. With respect to the functions of the display  58 , typical information displayed might include, but not limited to the following: battery indicator; manual suspension settings; maximum speed, tilt and vertical acceleration over the current ride, average speed, etc. 
     Referring to FIG. 8, the suspension system  12  is shown mounted to and extending between front parts of a two-wheeled vehicle V, such as a mountain bike. It also could be mounted to the front of a motorcycle. In this application, the suspension apparatus  10  of FIGS. 1-4 is employed to counteract the initiation of a dive condition due to the braking of the mountain bike V (or a motorcycle) by the cyclist. The anti-dive suspension apparatus  10  employs the sensor means  14 , the electronic module  16 , at least one actuator  18  and the power source  20 , as described above, in conjunction with the front suspension system  12  on the two-wheeled vehicle V for actively adjusting the front suspension system  12  of the two-wheeled vehicle V in order to counteract the initiation of the dive condition due to braking by the cyclist. The front suspension system  12  is mounted to and between first and second parts F, W of the two-wheeled vehicle V movable relative to and toward one another in response to the braking action being applied to the vehicle V. The front suspension system  12  includes first means  22  connected between the first and second relative movable parts F, W of the vehicle V and being contractible in response to the first and second vehicle parts F, W moving toward one another due to the braking action and second means  24  connected to the first means  22  for controlling the amount of contraction of the first means  22 . 
     The sensor means  14  is mounted to either one of the first and second relative movable parts F, W of the vehicle V for sensing the deceleration of the vehicle V due to the braking action. The sensor means  14  can be either a biaxial (H,V) or a single axis (H) accelerometer. In a manner similar to that described above with respect to the various conditions of the bicycle being sensed there, the sensor means  14  of the anti-dive suspension apparatus  10  actively senses the deceleration of the vehicle v in the direction of travel H due to the application of the brakes and produces signals representative thereof as inputs to the electronics module  16 . As an alternative and when the biaxial accelerometer is being used, deceleration in the direction H can be sensed along with a downward acceleration in the direction V. The downward acceleration also indicates the start of hard braking and of a dive condition. 
     The electronics module  16  is mounted to the vehicle V and connected to the sensor means  14  for receiving the input from the sensor means  14 . The electronics module  16  processes the input and produces an output to the actuator means  18 . The actuator  18  is mounted to the vehicle v and coupled to the suspension system  12  for receiving the output from the electronics module and in response thereto for causing the second means  24  of the suspension system  12  to adjust the suspension system  12  by “stiffening” it, such as through closing the orifice  50  via operation of a suspension damping piezoelectric flapper valve. Such stiffening reduces the amount of contraction that the first means  22  can undergo and thereby prevents the resulting dive of the front end of the vehicle V downward toward its front wheel W and thus the ground. Once the deceleration is zero, the suspension system  12  is returned to its setting prior to the braking. It should be understood that the anti-dive apparatus  10  employed here can also be employed on motorcycles to prevent “sit-down” of the rear of the vechicle during acceleration. Fast acceleration of a motorcycle can be sensed and the rear shock absorber stiffened to prevent the sit-down condition. 
     It is thought that the present invention and its advantages will be understood from the foregoing description and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely preferred or exemplary embodiment thereof.